ABSTRACT In the Washington field the sediments penetrated by the drill range from the Eocene Wilcox group to Recent Mississippi River deposits. The structure at the Washington field is an east-west trending anticline with proven closure (in the downthrown side) against the upthrown side of a down to the coast east-west trending normal fault. The fault dips 45° south. A given stratigraphic interval :3th a rather uniform thin- ning on the upthrown side of the fault and the fault increases in throw with depth. TheSe two characteristics are indicative of faulting contem- poraneous with deposition. The fault dies out eastward and westward from the field. on the east side of the field the fault splits into two main branches. A branch on the north trends east.southeast and a branch on the south trends southeastward. The south branch seems to be pinching out rather abruptly in a southeastward direction. Another poss- ible fault of small throw occurs north of the north branch fault. In the downthrow block. reversal of dip into the upthrown side of the fault is found on all horizons from the Miocene J sand through the Heterogtegm correlation point. 01' these only the Miocene H and GJ+ sands have over 30 feet of anticlinal closure. Most of the clos- ure on the other horizons within the Miocene J to Heterostegjgga interval is closure formed by the. intersection of the anticline and the fault on the east and a local plunging of the anticline on the west. Anti- clinal development continues an unknown elevation above the flgte o- stegina horizon. 0n Eocene and Oligocene horizons. all closure is closure into the fault. Closure into the fault reaches a maximum of 125 feet on the MoodysBranch marl and Cockfield formations. Isopach maps of the Cockfield D. the Cockfield B, and the Miocene H sands show no conclusive relationship to the strmture. The Cockfield D sand‘pinches out to the west. The pinchout increases the closure on this sand many times over the structural closure. Differential compaca- tion of the Coclcfield B sand affects the structure on the B sand by ' causing sections 61 and 41+. ‘1‘. l4 3.. R. U E. to be at a relatively higher structural position than on the D sand. The Miocene H sand is a blanket deposit on which a linear, north-south trending heart shaped buildup has been superimposed. The buildup may be related to an eros- ional depression created by currents issuing from a tidal channel. 0n the Miocene H and 6.1+ horizons differential compaction of. the H sand caused a pronounced area of anticlinal closure to stand out on the crest of the anticline over the position of the buildup. Host Miocene produc- tion occurs within this pronounced area of anticlinal closure. Because it eacplains the main features of the structure and because it can explain a gravity minimum over the field, the ”salt ridge typo- thesis" is proposed as a theory for the origin cf the structure. Faulting probably began prior to the time of Sparta deposition and continued an unknown period of time after deposition of the Hetgrggtggim horizon. Anticlinal uplift had begun before Miocene 'A time and continued through Heteggstegim deposition. There were also local areas of uplift durirg the Cockfield. A thinning of the section due to anticlinal formation is found to the south of the present anticlinal high because regional tilting caused a northward shift of the gentle dipping anti- clinal structure. Oil production at the Washington field is from at least 5 sends in ii the Chickasawhay. formation (Meow). The trap for these sands is anticlinal. The Cockfield B and D same produce gas and condensate. Tb trap for the B sand is closure into the fault and a fault strati- graphic trap controls accumulation in the D sand. Three locations are recommended for additional exploration: 1. new zone in the fault block on the east side of the field. 2. The Wilcox and the Sparta alcrg the fault on the downthrown side. . 3. The Wilcox and the Sparta on the upthrown side of the fault on the anticline]. closure which is expected to occur at depth just to the north of the fault. provided that the "salt ridge hypothesis“ applies to the Washington field. iii M. S. THESIS A STRUCTIRAL AND SEDDENTARY STUDY (1" THE WASHINGTON FIELD ST . [ANDRE PARISH . IDUISIANA By GORDON swam! mm A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in Michigan State University. East Lansing. Michigan 1959 iv ACKNGJLEDGMENTS The writer wishes to thank the Sohio Petroleum Company who made this thesis possible by giving the writer the electric logs of all wells pertinent to a sttfly of the Hashington field. A special thank you is given to Mr. Walter WoJciechowski of Sohio and Dr. Fisher of the Mich- igan State University Geology Department. Mr. Wojciechowski was very helpful in obtaining the electric logs and in defining the problem. Dr. Fisher's guidance and his very helpful criticism of the paper are greatly appreciated. The writer also wishes to thank Dr. Prouty and Dr. Trow of the geology department for their helpful criticism. List of figures . . . . List of plates. . . .\ . Intmdmtiono e e o o o Imation. . O O O .4 Physiography. . . . Topography. . . Drainage. . . . Economic geography. TABLE OF CONTENTS History of development of Purpose...... MethOdSQooooo Previous work . . . Stratigraphy. . . . . . Stratigraphic chart Wilcox gI‘OUp. . . . Claiborne group . . Cane River formation. Sparta formation. . . the Washington field. Cook Mountain formation Cockfield formation . . Hoodys Branch marl. . . Yazoogroup...... Vicksburg group . . . . Chickasawhay formation. Grand Gulf group. . . . vi Page HHI—JH N CD\O\)U\U\\JN ll 12 13 13 1a 14 15 l6 l7 Catahoula formation . . . . "Frio" sands. .,. . . . Upper Catahoula Anahuac formation Fleming format ion Foley formation . . . Pleistocene series. . rRecent series . . . . Structure . . . . . . .'. sands.. Explanation to structure maps . Regional structure. . . ... . . Structure of the'washington field Faulting. . . . . . . . . . . Discussion of structure maps. . . . flgggzggtgglgg. correlation point. . . . lflocene A sand. 0 ,Miocene G-At sand. Miocene H sand. . Miocene J sand. . Vicksburg lime. . . . .» Moodys Branch marl. . . Cockfield B sand. Cockfield D sand. Summary of structure. . . Genesis of the‘washington field \ structure . . . . .2. . . . . . vii faulted anticline Page 18 is. l9 19 20 20 20 20 22A 22 22 24 28 28 30 31 .3u 36 38 uz #6 Sedimentation. . . O O O O I O O O O O C O O O O I O O O O 0 Review of large interval isopach maps . . . . . . . . . . Isopach map of the interval.He§e;os§§giga correlation point to the top of the MioceneA semi... . . . . . . Isopach map of the interval from the top of the Miocere A sand to the top of the Vicksburg lime . . . . . . . Isopach map of the interval from.the top of the burg lime to the tOp of the Moodys Branch marl. Isopach map of the interval from the top of the burg lime to the top of the Cockfield D sand. . Isopach maps of individual sands. . . . . The Cockfield D sand. . The Cockfield B sand. . The Miocene H sand. . . Sand-Shale ratio map. a o e 0 Geologic history of the‘Washington field. Prwmtlon. O O O O O O 0 O O O O C O O 0 Recommendations . . . . . . . . Summary and conclusions . . . . Bibliography. . . . . . . . . . List of wells . . . . . . . . . viii Vicks- Vicks— Page 63 63 63 66 71 73 73 75 78 86 88 95 ' 97 102 107 App. Figure l. ILLUSTRATIONS Figgges Page Stratigraphic Chart. Evangeline and St. Landry Parishes. Louisiana . . . . . . . . . . . . . . . .«. . . . . . . 8 . Explanation to map symbols. . . . . . . . . . . . . . . 23 Format-ion of Gulf Coast faulted anticline by the "bedding plane 811p hypOth851S o e e e e o e e e o o e o c e e e 58 h. North-south section of the basic anticline of the "salt ridge hypOthGSlsu o o e o o e o e o o o o o o o a e o o 58 Elaine Plate 1. Location of Washington Field. State Map . . . . . . . . * 2. Location of Washington Field. Parish Map . . . . . . . 3. Electric Log Characteristics of Correlation Points. . . MA. Line of Cross Sections. . . . . . . . . . . . . . . . . 4. North—South Cross Section of Washington.Field . . . . . 5. EastJWest Cross Section of Washington.Field . . . . . . Strugtgze Eggs. 6. Structure of Hashington Field Contoured on Heterostegina Correlation POint o e e e o e o e o e o e o e e e o e e 7. Structure of Washington Field Contoured on Top of Miocene Asandeoooooeoeoooooooeeooooooo 8. Structure of Washington Field Contoured on Top of Miocene G.“ Sand. 0 O O O O 0' O O 0 O O C 0 O O C O O C C O O O 9. Structure of Washington Field Contoured on Top of Miocene H &nd. 0 I O O O O O O O O O O O O O O O O O O O O O O 10. Structure of‘Washington Field Contoured on Top of Vicksburg Line 0 O O O O O C O O O O O O O O C O O O O O O O O C * All plates are in the map pocket. ix 15. 16. 17. 18. 19. 20. 21. 22. 23. Page Structure of Washington Field Contoured on Top of * ViCka‘lrg Lim O O O O I O O O O O O O O O O O O O 0 Structure of Washington Field Contoured on Top of Moodys Branch Marl .......................-.-....... Structure of Washington Field Contoured on Top of COCkrielstandeooeeeoeoeeoeooooo Structure of Washington Field Contoured “on Top of cxkfieldDSaIdee00.00.000.000... Iso pagh Hap} Isopach Map. of the Interval Top of Heterostegina Cor- relation Point to Top of Miocene A Saul. . . . . . . Isopach Map of the Interval Top of Miocene A Sand to TopofVicksbm‘gLineo............... Isopach Map of the Interval Top of Vicksburg Lime to TopofMoodysBranchMarl. . . . . . . . . . . . . . Isopach Map of the Interval Tap of Vicksburg Lime to the TOP Of the GOCkfield D Sand. 0 e e e e o o e e o IsopachHapOinoceneHSani. e e o c o o e o e o o Isopach Map of Interval Base of Miocene H Sand to Tap ofnloceneJSand.'.............o... Isopach Map of Cockfield B Sand.’ . . . . . . . . . . Isopach Map Of CockfieldD Sand. 0 e o e e o o e o o Sand/Shale Map of the Interval Heterostegina Correlation Pomt tOTOpcfnioceneJ Sam 0 o o e_e o e o e o 0 Area of Production for Miocene H, Cocszield B arr! D Sands........................ \ * All plates are in the map pocket. Daemon The Washington field is located in North Central St. Landry Parish. Louisiana about 3% miles northeast of the farming community of Washington. 50 miles west-northwest of Baton Rouge. 35 miles north of the oil center of Lafayette. ard about 75 miles north of the Gulf of Mexico (pls. 1 and 2). The field is approximately centered on the common corners of Tps. u and 5 s. and Re. a and 5 E. The field area lies chiefly in secs. 1m, #5. 60. 61. 63. and 6+, T.- 4 S, R. 4+ E.; secs. 29-33. T. it 8.. R 5 E.; secs. 1 and 68. T. 5 S.. R. it E.; arfl secs. 3-6. T. 5 S.. R. 5 E. Mach! Wm - The Washington field lies near the western edge of the Mississippi River alluvial valley. The alluvial valley is a low. mono- tonsouly flat plain slaping 5-8 feet per mile southward. Superimposed on this valley plain are the minor surface features produced by the natural levees. the back swarm areas between levees. abandoned stream channels and accretion scars. The levees may rise as much as 10 feet above the surrounding lowland. and they provide the maximum local relief (Varvaro. 1957). The surface elevation of the Washington field varies from a maximum of 39.1 feet in section 1+4. T. 4 S.. R. 1+ E. on the levee of Bayou Boeuf to less than 20 feet along Bayou Wauksha in the inter- levee area. The only areas classified as swamps in the field are small areas located in the centers of sections 8. 9. and 61. T. it 3.. R. 1+ E. (Opelousas Quadrangle. Louisiana. 1958 Edition). A few miles to the west of the field lie the Pleistocene terrace uplands which form .an abrupt escarpment where they meet the alluvial valley (Varvaro. 1958). W - The Washington field area belongs to the Mississippi River alluvial valley drainage system. The Atchafalaya River. a few miles to the east. is the largest stream in the area; and it controls most of the drainage. Most of the drainage is south and southeast into the Atchafalaya River Basin by way of Bayou Courtableau. The drainage is controlled by a series of natural levees of the old Mississippi and Red ' River channels alternating with inter-levee swamp basins (Varvaro. 1957). Warsaw Basically. the econonv of St. Landry Parish is a farm econonw. Cotton. rice. sugar cane. and sweet potatoes are the important export crops. Livestock is raised extensively. and timber is an important resource. Oil an! gas fields are abundant in the area. the Washington field being one of 13 in the parish. Some of the more important fields in the parish are: Port Barre. Shuteston. North Cankton. Krotz Springs. and Boeco Fields (Varvaro. 1957). In the area of the Washington field. much of the land. because it is low. and poorly drained. is forested. oh the higher better drained areas. such as along the natural levees. the land is farmed. One can get an idea of land utilization by referring to the fee owners of the individual wells. It can be noticed that the Thistlewaite Lumber and the Thistlewaite Planting Companies control a major portion of the land. The population of St. Landry Parish was 78.105 in 1950. Host of the people are descendants of the Acadians about whom Longfellow wrote his "Bvargeline." The nearest town of any size is Opelousas located about 8 miles southwast of the field. It had a population of 11.659 in 1950. Washington. for which the field was naned. is a small farm comunity with a population of 1291 (Varvaro. 1957). Highways U. S. 167 and U. S. 190 serve the town of Opelousas. U. S. 167. a main north-south highway. connects the area with the Oil cen- ter‘of Lafayette to the south and the town of Alexandria in the north. U. S. 190 is the main road west from Baton Rouge. To reach the field from Opelousas. U. S. 167 is taken north to the town of Nuba. At Nuba. La. 10. a narrow hard surface road. is taken northeast through washington. It passes by the northwest edge of the field 3 or u miles north of wash- ington. From La. 10. the field is reached by a number of improved dirt or gravel roads. The Southern Pacific Railroad also serves the area and passes through both opelousas and Washington (Varvaro. 1957). There is a network of pipelines in the area. The Continental Oil pipeline and the Transcontinental Gas Pipe Line Corporation pipeline serve the field (Oil and Gas Map of Louisiana. 1956). Histglz 9f Develomm; 9f thg WashW In 1937. the Strake Oil Company contracted the Hoard Exploration Compam' to do reflection seismograph work in the area of the Washirgton field. After an extensive amount of detailed work. the Strake Oil Compam' selected and retained 6.662 acres out of its original lease from the Thistlewaite Lumber Company centered arouni sec. 61. T. 1+ 3.. R. u E. The HertOn Oil Company leased by assignment from the Strake Oil Compamr one half interest in their‘acreage. The Herton Oil Company began drilling their Thistlewaite Lumber Company No. 1 well on August 17. 1938 in see. 6001‘. u 5.. R. uE. They drilled to a total depth of 11.220 feet. stopping in shale. No oil shows were reported; however the well was reported to have tried to blow out while drilling at an approx- imate depth of 9.650 feet. This attempted blowout may have been due to the thin Cockfield D gas sand at 9220 feet because 9650 feet is in a shale section. The Sohio Petroleum Company's scout book reports a gas show in the Wilcox. Whatever showings the Herton Company had. they apparently were not significant enough to stimulate interest; and the well was abandoned October 9. 1938. In 1941. Strake Oil Company drOpped its acreage (Oil and Gas Field Development in the United States. Yearbook 1938-1901). , Stanolind in 1942 acquired a geOphysical option in the area and turned part of its interest over to Amerada who was to shoot the area with reflection seismograph. After seismic work. the acreage was drOpped (Oil and Gas Field Development in the United States. Yearbook 19%). In 19%. the Sohio Petroleum Company began to seismograph the area. They began to drill their Thistlewaite Lumber Company No. 1 well in section 64. T. Liv 5.. R. “E. in August 1951. The well was drilled to a total depth of 12. 505 feet. 1000 feet into the Wilcox. A gas sand 27 feet thick. later named the Cockfield D sand. was encountered in the COckfield formation. The well was completed in’this sand through perfor- ations from 9287 to 9291 feet. The initial production was 75 barrels of condensate. 6O API gravity. and 1.040 HCFG per day on a 1/8 inch choke. having a gas-oil ratio of 13.800 to 1. Production from the 3m zone was opened in December 1952 by the Thistlewaite Lumber Company No. tr well in section 61. T. 1+ S.. R. h E. it the present time there are two producing gas sands. The Cockfield B and D sands. and 5 producing oil sands. all in the W zone (Varvaro. 1957). \ Drilling has continued from the time of discovery to the present. and there is now a total Of 14 oil wells and 18 gas wells in the field. Recently a recycling program has been established for pressure maintenance of the Cockfield B and D reservoirs. Sohio Petroleum Company and Gulf Refining Company are the principal lessees of the field acreage. Sohio has been designated as the operator of all Sohio-Gulf acreage. Burma; The main objectives of this paper are to study two phases of the geolOgy of the‘Washington field using electric logs. namely the struc- ture and the influence of structure on sedimentation. The study is confined mainly to a 3700 feet stratigraphic interval extending from.the . top of the fietgrostegina lime of the Miocene Anahuac formation. at a depth of about 5600 feet. to the base of the Cockfield D sand of the Cockfield formation at about 9300 feet. The upper limit is fixed by the highest electric log correlation which can be carried across the field. The lower limit is controlled by the total depth of the wells. Only a few wells penetrate to a greater depth than the Cockfield. Methgdg ' In the summer of 1957 while working with the Sohio Petroleum.Com_ pany in Lafayette. Louisiana. the writer was given the electric logs of all wells pertinent to a structural and sedimentary study of the‘Wash- ington field. The study was carried out entirely from the electric logs of the individual Oil wells. 1 total of 39 wells was used in the study. ‘Wells lying within the area of the base map. but outside the area of the field were spotted on the base map. but they were not used in this report. In making correlations. an eastawest cross section was made using 12 electric logs. Persistent electric log characteristics were picked as correlation points and carried across the cross section (pl. 3). All other wells were compared with the cross section. and the correl- ation points were marked on them. Most of the datum points used in mapping were taken from correlation points. In the Gulf Coast nearly all faulting is normal. When compared to wells containing a normal stratigraphic section. faulted wells are seen to be missing section. All faults are plotted as thlck broken lines with throw plotted on the upthrown side (fig. 2). Although a smaller contour interval might be desirable on the crest of the structure. the writer felt that a 50 feet interval was the maxi- mum.he could use without cluttering on the map in certain.areas. and the minbmum he could use without losing important structuralcdetail. To study possible structural effects on sedimentation. individual sands and intervals between correlation points were mapped. If the structure was rising during the deposition of a given interval. a topographic high would be created on the sea floor. Because the high would be exposed to greater current and wave action than the surrounp ding sea floor. a given stratigraphic interval would be expected to thin over the high. If a depressionnwere forming. the inverse would be expected. Individual sands were not only studied to see if their dapp- sition was controlled by structure. but they were studied to see if they effected the structure as a result of’differential compaction. Indivi- dual sands were also studied in an attempt to determine their origin. A sand-shale ratio map was also made to look for structural.effects on sedimentation. If a rising structure formed a positive enough feature on the sea floor. increased action of waves and currents over the high would be expected to winnow out more of the fine elastics leaving a greater concentration of sand. and should show up on the sand-shale- ratio map. A sand-shale ratio was determined by taking a line on the self potential side of the electric log midway between the shale base line and the line of maximum sand development and then determining the sand and the shale thicknesses (method suggested by a Sohio geologist). W The Sohio Petroleum Company at Lafayette. Louisiana has considered publishing a report on the Washington field in a Gulf Coast geological publication in the near future. If this report has not appeared. the writer knows of no published report on the geology of Vashington field. and the only work done on the field. to the writer's knowledge would be that which a comparv normally does in oil field development. FIGURE l STRATIGRAPHIC CHART EVANG‘LINE AND 31" LANDRY PARISHES. LOUISIANA Source: L0- Dept Cons. Gaol. Bull. NO. 3| CANE RIVER :3 9.1 3 % “‘GNOST'C F055“ RELATIVE PosmON OF SEA m a: c: 3 ”WWW r °' (macawwanc) 5 a 5 O AUNAL ZONES a a m": tin-"“3 ( z .3 5 g name .2 8 muons" 3 E: serum 3 mum“ g uawou a use FOLEY 3 (Jones) "up own an." 7 W hinted - W. W use FLEIONC .00 at w M DOOM ? ‘33 W a z N o m m 0 O < uncommon and loud" me an 9 r: 3 -' ANAHUAC WM W and 3 b a: 3 W We no. é o i W Ila-OI an m m g 8 «”6 2:51;!“ Maura 3 Heathen, 030:8... " Mouton am 1’ 7 ? mu m g ,. ,_ g musnuav 2 '- C 0 “- S 8 g We meal, Amelia. .1 .— 3 murrcasunnto :‘mmlls. swim sumo, <2: :3 chew: cocoons“ 2 Wooden conceals ‘ Mules bottom“. 2 3 § mnensunnso mrww g (Q ‘ Dullmlno ham > numeric mum .1 g numeric chums. E W3 m" Coach? ~73 and 2 if was “munch E g COCKFIELD w m: o U § 3 u fr:— WON“ ”In“ 2 we» unbound. ¢ 8 mm mm 8 8 000:: uouuum terminus. m g 3 WM 0. 0 ”7"“ Cycllmmino up. ammo». Miami's mnlim mm Weenies om) [gem Mcox UNOIFFERENTIATED sm. grmm General In St. Landry Parish. the sediments penetrated by the drill range from Mississippi River alluvium of Recent age to Wilcox sands of lower Eocene age (fig. 1). Most of these sediments are Tertiary in age. They represent a complex series of deltaic' sediments separated by transitional and marine phases (Varvaro. 1957). These sediments were deposited on the north flank of the sedimentary basin known as the Gulf Coast geosyn- cline where they have accumulated to a thickness of over 30.000 feet along the present coastline. The. individual time rock units are wedge shaped and thicken Gulfward. Taken together. they may be pictured as a series of Gulfward dipping wedges. each wedge having two distinct rates of dip separated by a zone of rapid transition known as the flexure zone. 'Northward from the flexure zone. the beds dip at a constant rate of a few feet per mile. Gulfward from the flexure zone. the dip increases geOmtrically. and the thickness of the ind ividual wedges increase prep— ortionally. This change of dip and change in theLrate of thickening is produced by more rapid subsidence'on the Gulf side of the flexure during deposition. Continued subsidence during deposition of the overlying wedges causes a significant increase of dip with depth. The dip changes from a few feet per mile on the surface sediments to more than 200 feet per mile on the Eocene sediments. Each younger wedge lies progressively Gulfward. offlapping in response to a Gulfward shifting of the zone of maximmn subsidence through Cenozoic tim (Lowman. 1949). Within the overall picture of marine offlap or regression there are cyclic depositional sequences involving both major and minor marine trans- 10 gressions and regressions. The sedimentary cycle is generally composed of three major components. The. cycle begins with a 'rapid transgressive phase which deposits a thin marine. calcareous. and glauconitic sand or marl action. The transgressive phase grades upward into an inundat ive phase that slowly deposits a thicker marine Shale and clay section. The clay may be sandy and may contain some glauconitic and calcareous units. The inundat ive phase grades upward into a prominent regressive phase that deposits a massive to broken. carbonaceous to lignitic sand and clay with local glauconitic and fossiliferous beds. The.pycle generally closes with a disconformity following the regression (Murray. 1952). The Gulf Coast Tertiary is divided into natural time rock units by these cycles. a stage being the time rock unit which is given to a major cycle. Each major cycle contains numerous minor cycles to make further subdivision possible. In deltaic sedimentation. fluviatile. brackish water. and marine environments are closely associated. Shifting of the strand line has produced a haphazard arrangement of the sediments of these environments. Landward. the fluviatile sediments thicken and become dominant; seaward. the_sands thin and marine clays and shales thicken. There is then a change from continental sediments to marine sediments as one follows a sedimentary unit downdip (Varvaro. 1957). All sediments in the Central and'Uestern Gulf Coast can be divided into two major facies. the sand facies and the clay marl facies. Murray (1952) describes these facies as follows: "The sand facies is characteristic of the fluviatile and brackish water or marginal mrine environment and is characterized by an excess of sand over clay. shale. or marl. It contains blanket sands of great areal extent in relation to thickness. of lenticular sands of 11 varying areal thickness. and of blanket sand zones in which a zone of lenticular sands has great areal extent relative to thickness. The clay marl facies has an excess of lime and fine clastics over coarse detritus. The marls. which may be arenaoeous. are generally extensive but are thinner and less well developed than the clays or shales. The clay and marl facies generally represents a marine and marine deltaic environ- ment." The individual sedimentary facies generally parallel the bay line (a curving line connecting the landward edges of principal coastal lakes and bays) of the present coast (Lowman. l9'+9). During Eocene and Oligocene time. the bay line was deflected inland by the Mississippi embayment. a structural trough with a north-south trending axis lying in about the same position as the lower Mississippi River. Changes .in facies along the strand line are generally very gradual. is one moves westward along the strand line. a slight increase in the arenaceom content of the sediments is noted; and as one moves eastward. a slight increase in calcareous content is noted. Wilcox Grggp The Wilcox group is reached at a depth of 11.468 in well 23. the discovery well of Washington field. This well was drilled 1,000 feet into the Wilcox. It and well- 28 are the only wells. in Washington field to reach this group. The Wilcox group. according to Varvaro (1955). is a lithologic unit. It represents a deltaic to marginal facies of mrine regression during Sabine time. It consists of fine to medium grained. fossiliferous, and calcareous sands and interbodded shales. The shales are calcareous and dark to gray colored. The sends in the section penetrated predom- ’nate. are lenticular. and contain numerous shale breaks. On the electric log the tOp 200 feet of the Wilcox is characterized by a poorly developed S. P. (spontaneous potential) curve coupled with a very high resistivity. This would probably indicate a fine grained rather tight sand. The next 800 feet have a better developed 3. P. ard a slightly . lower resistivity opposite the sand units. Wilcox sands produce in the nearby Palmetto and Melville fields. but at present there is no production from them at the Washington field. The Wilcox is overlain disconfomably by the Cane River marl member of the Cane River formation. ai Grou The Claiborne group includes all sediments from the top of the Wilcox to the base of Moodys Branch marl. It includes two depositional cycles in the Washington field. the Cane River-Sparta cycle and the Cook Hountain-Cockfield cycle. The formational units represent facies of these cycles (Varvaro. 1957). Qaaa_iizazlionmaiiaa According to varvaro (1957). the Cane River formation represents the transgressive and inundative phase of the Cane River-Sparta deposi- tional cycle. The top of the Cane River is reached at a depth of 10.5140 feet in the discovery well. It consists of 100 feet of glauconitic. fossiliferous. and sandy basal marl. known as the Cane River marl. over- lain by about 70C feet of clays and mudstones. 0n the electric log. the marl member has a small 3. P. kick that is 15 to 20 millivolts greater than the shale base line and a very high resistivity. The overlaying claysection has a shale base line S. P. curve ard a very low resistivity. The Cane River shale is transitional into the overlaying Sparta formation. Sparta Fgmtion The Sparta formation represents the updip regressive phase of the Cane River-Sparta cycle of deposition (Varvaro. 1957). The Sparta formation is reached at a depth of 10.160 feet in the discovery well. It consists of 500 feet of fine grained calcareous sands-and sandy marls interbedded with shales. 0n the electric log. the Sparta formation has a fairly strong S. P. kick combined with a high resistivity kick opposite the sand units. The shale units have a much lower resistivity and S. P. than the sand units. The Sparta in the Washington field is not produc- tive. It is productive both updip and downdip from the field. and it is an important producer in nearby Melville. Opelousas. and Port Barre fields. It is disconformably overlain by the Cook Mountain marl (Sparta \ lime). 0.2M Mo Winn According to Varvaro (1957). the Cook Mountain represents the down— dip transgressive and inundative phase of the Cook Hountain-Cockfield cycle ofedeposition. It is reached at a depth of 9320 feet in the discovery well. This formation consists of 250 feet of gray. glaucon- itic. and sandy basal marl known as either the Cook Mountain marl or the Sparta lime. and about 550 feet of calcareous mudstones and clays. The electric log of this section has a shale S. P. curve opposite the shale section and a slightly greater 3. P. development Opposite the marl mem- ber. The electric log shows a large resistivity opposite the marl and 14 an irregular resistivity opposite the shale section. the resistivity probably being greatest where the lime content is the greatest. The Cook Mountain is transitional into the overlying Cockfield formation. W , The Cockfield formation. which is also called Yegua fomation. represents the regressive updip phase of the Cook Hountain-Cockfield cycle of deposition (Varvaro. 1957). In the discovery well.: it is reached at a depth of 8900 feet and is l+20 feet thick. It consists mainly of brown to gray lignitic and micaceous silts and shales containing a few stringers of gray. fine grained micaceous and silty sands. The top of the formation is slightly calcareous. In the Washington field there are only three sands of significant thickness in the Cockfield. These are the B sand and the D sand (pl. 3). both of which are productive. and another unproductive sand 70 feet thick founi only in three wells in section 3. The Cockfield is disconformably overlain by the Hoodys Branch marl. Moodys Branch Mar; ngtigg The Moodys Branch marl is a basal marine concentrate deposited by a transgressing Jackson sea following a regression during the Cockfield (Varvaro) . Hoodys Branch marl is reached at a depth of 8880 feet in the discovery well and consists of from a few to 30 feet of fossiliferous sandy to clayey. glauconitic marl (pl. 3). This formation has wide areal extent and is one of the most extensively used marker horizons in regional correlation. It is transitional into the overlying Yazoo clays. 15 lazoo Gro g9 overlying Moodys Branch marl and uxflerlying the Vicksburg is a group of midifferentiated argillaceous deposits of the Jackson stage known as the Jackson shale or the Yazoo group. It is typically argil- 1aceous and varies from carbonaceous and silty clays to calcareous. glauconitic. and fossiliferous clays. It is transitional into the over- lying Vicksburg lime by an upward increasing lime content (Varvaro. 1957). On the electric log. the resistivity increases upward as it grades into the overlying Vicksburg. Because there is no lithologic break to sepa- rate the two. they'mnst be differentiated by paleontology (fig. 1). In well 23. the Jackson and the Vicksburg line together have a thickness of 14.57 feet. TheJackson thins eastward. The tap of the Jackson marks the top of the Eocene series. We: The Vicksburg group is reached at a depth of 8200 feet in well 23. the discovery well. The lower portion of the Vicksburg is made up of a I hard. white. fossiliferous. and glauconitic marl known as the Vicksburg lime (pl. 3). This zone has a distinctive resistivity kick on the elec- tric log. and it was used as .a correlation point. The Vicksburg lime was reached at a depth of 821m feet in well 23. Overlying the Vicksburg lime. is a sandy shale and lignitic clay zone 250 feet thick. It is separated from the Vicksburg lime by a sharp decrease in resistivity (pl. 3). The Vicksburg lime thins southward and eastward. and the over- lying sandy shale and lignitic clay zone thickens southward and east- Ward . 16 Bates (l9ltl) reports an unconformity at the top of the sandy and lignitic shale section overlying the Vicksburg lime. He reports that the shale section thins rapidly undip and that the upper half of the Vicksburg lime disappears updip in the vicinity of Marksville. Iouisiana. Overlying this shale is the Chickas‘awhay formation which is discon- formable with the Vicksburg. if the thinning of the Vicksburg shale section indicates a surface of erosion. Chigkasghgy Formatiog Varvaro (1957) uses the fomational name Chickasawhay to apply to those marine strata overlying the Vicksburg group and containing M91. 3213 W and their equivalents. The ChickasaWhay is equivalent to the lower Frio of Reedy (1949). and the sands of the formation are often called the 1m sands. Varvaro. on his north-south cross section of St. Landry Parish. picks the top of the Chickasawbay at a depth of 7530 feet in well 23. The Chickasawhay is composed of marginal generally thin to massive sands interbedded with dark marim shales. The sands generally contain numerous small shale breaks. Lithologically this form- ation is transitional into the underlying Vicksburg and is differentiated from the Vicksburg by the first appearance of W mi. The Chickasawhay contains many blanket sand deposits. The Miocene H and J sands can be carried across the field and are examples of blanket sands. Because of their persistent character. they were med as mapping horizons. Typical electric log characteristics‘of the Chickasawhay formation may be seen by referring to the Miocene 0.3+. H. and J sands in plate three. The Chickasawhay is approximately 650 feet thick in well 23. It thickens southward. In the southern part of the parish. it is known to thicken l7 considerably on the downthrown side of east-west trerd ing faults due to faulting contemporaneous with deposition. The Chickasawhay contains at least five producing sands in the Washington field. They are the Miocene E. F, 0.3, H. and J sands. The Chickasawhay formation grades into the overlying Catahoula formation. and the two can be differentiated only by paleontology. There is much controversy as to whether or not ~the Chickasawhay is oinocene or Oligocene age. As can be noted from the naming of the G. H. and J sands. the Sohio geologists consider it to be of Miocene age. There are aenumber of reasons for placing the Chickasawhay at the base of the lower Miocene. According to Waters. McFarland. and Lee (1955) . as well as many other paleontologists. 31W .W marks the begin- ning of the lower Miocene. As previously mentioned. the tOp of the Vick- sburg shale section has a possible unconformityat its top (Bates. 19%) . indicating a possibly significant depositional break between the Vicksburg and the Chickasawhay. A marked change in the lithology takes place be- tween the Vicksburg shale and the Chickasawhay formation. The Vicksburg marks the end of active marine sedimentation inthe Central Gulf Coast. Following. and possibly beginning with the close of the Vicksburg. there was a major regression of the sea and all the lithology above the Vick- sburg represents continental and near shore marine deposition. ngg Gglf nggp The Grand Gulf group includes all Miocene sediments above the Chic k- asawhay. Regional correlation of this group through the Gulf Coast. be- cause of very rapid horizontal and vertical facies changes. generally has to be done by paleontology. The group consists of the Catahoula. the -18 Anahuac. and the Fleming formations (Varvaro. 1957). Cth F0 n The Catahoula formation in the area of the Washington field con— sists of two massive deltaic wedges separated by the intertonguing marine sediments of the Anahuac formation. The name "Frio" sands is utilized for the sands beneath the Anahuac and the name Upper Catahoula sands for the sands above the Anahuac (Varvaro. 1957). "F: i0" Sag; - The ”Frio" sands in the Washington field consists of massive deltaic and marginal marine sands separated by marine shales. According to Varvaro (1955). the "Frio" sands are reached in well 23 at a depth of 51% feet and are approximately 1400 feet thick. The sands contain many small shale breaks and constitute the majority of the "Frio" sands. Lithologically the "Frio" sands differ from the underlying Chickasawhay only in having slightly greater and slightly more massive development of the sand units and a lesser development of the shale units. Facies changes seem to be more rapid in the "Frio' sands than in the underlying Chickasawhay. for the Miocene J sand was the only sand which could be carried across the field (pl. 3). 0n the electric log the "Frio" sands appears much as the 'Anahuac. The only differences between the two is that portions of the Anahuac contain a significant amount of lime and therefore have a higher resistivity. and that the Anahuac has a slightly greater development of the shale units. The "Fric" sands and all other sedimentary units above it are not prod uctive in the Washing- ton field. The "Frio" sands are‘conformable with both the underlying Chickasawhay and the overlying Anahuac. 10. £19ng - The upper Catahoula sands consists of mass- ive deltaic sands interbedded with marine shales. These sands are much more massive than those of the "Frio" sands. some of them being over 500' feet thick with only minor shale breaks. The upper limit of the Cata- houla is defined by the base of abundant Rotalia becggri. and the lower limit is defined by the appearance of fossils of the Disggrbis zone (fig. 1). Anahggc Formatiog The Anahuac formation overlies the "Frio" sands and is transitional into them (Varvaro. 1957). It represents a transgressive marine wedge between the two regressive units of the Catahoula. It is divided into three paleontological zones. the W zone at the base. the m- m zone in the middle. and the Disgorbis zone at the top. The Anahuac is rather far updip in the Washington field and has not developed its typical marine shale lithology. Except for the Heterostegiga zone. the formation appears much the same as the underlying 'Frio" sands. It contains nerginal marine sands interbedded with marine shale. The Hetggostggm zone is distinctive in that it contains a great amount of calcareous material and has a strong resistive kick on the electric log. One strong resistive kick at the tap of the Hetergstegigg zone was very persistent in all wells in the field and’was med as a mapping horizon (pl. 3). This resistive kick was also the highest electric log charac- teristic which could be carried across the field and was therefore the highest correlation point. According to Varvaro (1957) . the Anahuac formation is reached at a depth of 5575 feet and has a thickness of about 500 feet in well 23. It grades rather abruptly into the massive sands of 20 the upper Catahoula. Because of the Anahuac's transitional boundaries. paleontology is used to define its limits. Fleming rmtion Overlying the Catahoula are the deltaic sands. silts. arri clays of the Fleming. Its top ard base are determined by paleontology. The base of the abundant Rotglia 1229.93.21. marks its base. and the top of the 3m; 19.1mm - hieramia aismlahnéaai zone marks its tap (Varvaro. 1957). Fglfl Fgmtiog Between the Fleming and the Pleistocene deposits is a series of lignitic and micaceous. typically deltaic sands. silts. and clays of varying thickness containing gravel lenses. These sediments have been named the Foley formation and are considered to be Pliocene in age be- cause the top of the Miocene is marked by m m (Varvaro. 1957). flgistggege Sgrigs Overlying the Pliocene deposits. are a number of fluviatile and deltaic gravels deposited during interglacial times in valleys cut during glacial stages. Each deposit grades upward‘from gravels at the base to silts at the top. They range from a few to 250 feet thick. From top to bottom these deposits are: Prairie formation. Montgomery formation. .Ben- tley formation. ani Williana formation. The Prairie formation at the Washington field is overlain by sedi- ments of the Recent series (Varvaro. 1957). Recent grgg The youigest sediments encountered at the Washington field are the flood plain deposits of the Mississippi River. They are much like the Pleistocene deposits. grading from gravels at the base to fine clays at the top. They are deposited in a pro-Recent trench out into the Pleis- tocene deposits during the last glacial epoch. According to a contoured map of the trench by Fisk (1947). these sediments are less than 100 feet thick at the Washington field. For a more complete discussion of the regional stratigraptv. the reader is referred to works by Murray (1947. 1952). Varvaro (1955). Waters et a1 (1955). Bornhauser (1947. 1950. and 1958). Howe (1933). Lowman (1999). Carsey (1950). Reedy (1949). Storm (1945). Allisor (191W). Halkin ani Jung (1941). Todd and Roper (1940). Culbertson (1940). Fisk (19in). Bates (191.1). and Fisk (1947). 22 smuc'rm WW Structurally. the sedimentary complex of the Gulf Coastal Province has been controlled by two great structural downwarps. the deep east- west striking Gulf Coast geosyncline with its axis just off the present coastline and the shallower north-south Mississippi structural trough with its axis under the present M1ssissippi River (Murray. 1949). The regional structure produced by these troughs is a broad homocline striking between north 80 degrees east and north 80 degrees west and dipping Gulf- ward from a few feet per mile on surface outcrops to nearly 200 feet per mile at depths below 10.000 feet (Varvaro. 1957). The effects of the Mississippi trough on the regional strmture are the most pronounced in the Eocene. with some effects also observed in the Oligocene. Regional structural contours of the Eocene have‘sharp re-entrants into the trough (Hurray. 19W). Each sedimentary unit has two distinct rates of Gulfward dip sepa- rated by a zone of rapid transition. Landward from the break in dip. the sediments dip Gulfward at a constant rate of a few feet per mile. Coast- ward from the break. the dip increases geometrically Gulfward. The belt of rapid change or break in dip is known as a hinge belt or flexure zone. and it is the locus of considerable faulting. The faults generally strike east-west and have a maximum throw of 500 feet. The flexure zone for each yourger series of sediments shifts Gulfward (Lowman. 1947). Superimposed on the regional structure are local structures. many of which are related to the flexures. They consist of structural noses. deep seated salt domes. piercement salt domes. and complexly faulted 23 FIGURE 2 EXPLANATION TO MAPS WELL LEGEND O OIL WELL {I «fl» GAS-CONDENSATE WELL + {1. GAS WELL ‘Q DRY HOLE 2 WELL NUMBER USED ON MAP 1- 86.48 DEPTH BELOW SEA LEVEL OF CONTOURED HORIZON (STRUCTURE MAPS) HICKNESS IN FEET 0F GIVEN INTERVAL (ISOPACH MAPS) FAULTING 250' (:FEET 0F THROW) PTHROWN SIDE) L... k fiFAULT uw DEI THROW" 5‘ FAULT 0 (DOWN . WELL FAULTED AT A DEPTH OF 3090 FEET 250 ”8090 gAULT HAS 250 FEET oF THROW Q OIL PRODUCTION OCCURS ONLY IN THE MIOCENE SANDS~ T GAS AND GAS-CONDENSATE PRODUCTION OCCURS ONLY IN THE EOCENE COCKFIELD SANDS- THE WELL NAME, OPERATOR, LOCATION, ELEVATION OF DERRICK FLOOR ABOVE MEAN SEA LEVEL, TOTAL DEPTH, AND COMPLETION DATE MAY BE FOUND IN THE APPENDIX WHERE THEY ARE LISTED xOORDING TO THE WELL NUMBER WHICH APPEARS ON THE MAPS- 21+ anticlines. which may also be related to salt intrusions (Yarvaro. 1957). S of W trF' d \ The Hashington field is an east-west trending ant icline having closure on the north against the upthrown side of an east-west. down to the coast. normal fault (fig. 2. pls. LIA and 4 to 11+). Faulting All faulting in this area is normal and prodmes missing section in a well. Faulting was fourd in nine wells on the north and east side of, the field. Using wells 5. 16. art! 28 in a three point problem. the writer found the fault to strike east-west and dip 41W 5. Using wells 140. 41. ard 42. the strike was N 40° W with a dip of “6° SW. Because the fault is concave southward between wells 5 and 28 and between wells 40 and ’42. the true dip would be slightly greater than 45°. Quarles (1953) made a sttfly of Gulf Coast characteristics, and he found all faults to have a h5° dip plus or minus 10°. This together with the three point problem should be sufficient reason for showing a 145° dip on the . fault at the Washington field. ' By referring to plates 6-14. one can see that the fault splits at some point just beyond well 39. Wells ’40. 41.5and 42 are faulted. faults beirg intercepted at depths bemeen 8287 and 9795 feet in each well. The fault shows a rather uniform southeastward decrease in throw. decreasing from 175 feet in well #0 to 125 feet in well 1+2. The most reasonable interpretation on the faulting in these three wells would be one fault that strikes north-northwest and gradually dies out southeastward. This. fault is shown by the southernmost fault on the east side of the‘field. and throughout this report it is referred to as the south branch fault. Another fault of 80 feet ttu‘ow is found in well 1414 at a depth of 7684 feet. Unless a right angle turn is taken in the strike of the fault found in wells 40. 41. and 1+2 just southeast of well 1+2. another branch of the fault must be mapped to the north of the south branch fault. This fault is referred to in this report as the north branch fault. Because only one fault is found in wells 38. 1+0. 1+1. and 1+2 and because‘there is a rapid decrease in throw between well 39 and well ’40. the most logical place for the fault to split is at some point just eastward of well 39. the fault swinging outward from well 40 far enough so as not to be inter- cepted by that well. The combined throw of both the north and south branch faults approximates the throw of the fault found in well 39. This is evidence that vertical adjustment on the east side of the field is divided between the two fault planes. in well ’44. a possible fault with a maximum throw of 50 feet is found at a depth of 9184 feet. The nearest well for comparison is well 1+1 which is more than a mile and a half west- ward. The two wells lie on opposite sides of the north branch fault. and the apparent missing section may possibly be due to sedimentary change. It is therefore mapped as a questionable fault. Faulting in the Hashington field seems to be exemplary of faulting contemporaneous with deposition. When faulting occurs contemporaneous with deposition. one expects the throw of afault to become greater with increasing depth. the throw being compensated for upward by a greater thickness of sediments on the downthrown side of the fault. While a given bed is forming. it has a relative sinking movement on the down- thrown side of the fault. The action of currents and waves tend to maintain a profile of equilibrium; thus a greater thickness cf sediments 26 is received on the downthrown block. The amount of thickening on the downthrown block is equal to the amount necessary to compensate for the relative vertical displacement along the fault. The following evidence for faulting contemporaneous with deposition is found at the Washington field: (1) Consider wells 5. l6. and 28 (p13. 6-23). In well 16 a 240 feet fault is intercepted at a depth of 7463 feet. In well 5 a fault of 300 feet throw is intercepted at-a depth of 8957 feet. In well 28 a 380 feet fault is intercepted at a depth of 10,001+ feet. Because these wells are only a mile apart. it would seem most reasonable to interpret this as throw increasing with depth rather than horizontal variation in throw. Therefore the writer shows the fault to increase in throw'with depth. being a minimum on m ste 1 . the shallowest mapping horizon.(pl. 6) and the maximum on'the Cockfield D sand. the deepest mapping horizon (pl. 11?). This increase in the throw of the fault with depth is apparent along the entire length of the fault. but one must first consider the effects of an eastward and westward decrease in throw. (2) A well adjacent to the fault on the upthrown side has a thinner stratigraphic section than a well adjacent to the fault on the downthrown side. Referring to the north-south cross section (pls. 4A and 1+). notice that the interval between the Miocene J sand' and the top of of the Vicksburg lime is 33efeet thinner in well 16 than in well 11. and ' that the interval from the top of the Miocene H sand to the top of the Vicksburg lime is 55 feet thinner in well 16. Below a depth of 10,001+ feet well 28 is drilled into the upthrown block of the fault. If the Cane River shale of this upthrown block is compared with the Cane River shale of well 23 on the downthrown block. it is found to be 55 feet thin- ner in well 28 (not shown in the cross section). In comparing well 39 on the upthrown side of the fault with well 36 on the downthrown side. one can notice on plate 18 that the interval shown is 57. feet thinner in well 39.8 Again. in comparing well LIO on the downthrown side of the fault with well ’41 on the upthrown side of the fault. one can notice on plate 18 that that interval is 38 feet thinner in well ’41. This is a somewhat greater thinning than the expected regional thinning shown on plate 18. A greater thickness of sediments on the downthrown side of the fault seems to be substantiated by these evidences. This thickening accompanied with an increasing throw of the fault with depth are highly indicative of faulting contemporaneous with deposition. In comparing the throw of the fault in well 5 and in well 2. it is noticed that a fault of lesser throw at a greater depth is found in well 2. According to Varvaro (1955) in his cross section of the parish. a 200 feet fault at "a depth of 10.660 feet is recorded in a well drilled by Sohio in section 78. T. LI 8.. ,R. 1+ E.. This well is only 1% miles west of well 1. The deerease in throw westward [indicates that the fault is dying out in that direction. This is ‘also' supported) by Sohio's seismic work (personal letter) which shows the fault to die out about seven or eight miles west of well 1. A rapid decrease in throw of the south branch fault in a southeast direction indicates that it is rapidly dying out in that direction. The fault decreases in throw from 175 feet at a depth of 9795feet in well 140 to 125 feet at a depth of 9479 feet in well 1+2. Hell “4 is.the only control on the north branch. so what happens to it cannot be determined with t\he control available. However. on his structural map of Evangeline and St. Landry Parishes. Varvaro (1955) shows the fault to continue for at least 10 miles beyond well my It is conceivable that movement is transferred from the dying out south branch fault to the north branch fault in an eastward direction. It can be concluded that the fault has an east-west extent of at least 25 miles and that with the control available. the fault seems to have its maximum development 3 miles on either side of the common range line of Rs. 4 and 5 E.. gradually dying out both eastward and westward from this zone. Discussion of Structure Maps H r t ' C P - MW correlation point is the highest horizon mapped in this report (pls. 3. 4A. 4. 5. and 6). Because the throw of the fault decreases upward. this horizon shows the least amount of throw of any horizon mapped. Datum points of $88 feet in both wells 13 and 16 indicate a rever- sal from a south dip to a north dip as the beds approach the fault from the south forming an east-west trending anticline along the fault. The east end of the anticline probably closes against the fault. Whether or not the anticline plunges on the west so as to produce closure cannot be determined definitely bean control is not available along the fault on the west side of the field. The datum points in wells 1+ and 5 may indicate a slight develoment of a saddle in section #3 which may close the anticline on the west. Closure on this horizon as well as all deeper horizons may occur on the east side of the field in the fault block formed by the branching of the main fault. The contours in this fault block must intercept the south branch fault so as to produce the p‘Oper amount of throw. and they must strike in a direction determined by the datum in well 1614. Because 29 of these conditions the contours strike north-northeast and are inter- cepted by both the north and the south branch faultsforming over 400 feet of fault closure. - On this horizon as well as on all deeper horizons. the dip increases southward. the maximum dip occurring on the extreme south limb of the structure on the east side of the field. downdip from well 1&0. The dip between well #0 and well 1+3 on this horizon is approximately 190 feet per mile. ' 0n the east side of the field on a line of strike with well 140. the dip changes rather abruptly from 190 feet ‘per mile downdip to 135 feet updip. On this horizon this break in dip seems to hinge upon the 5800 feet contour. The break becomes even more apparent on deeper horizons. and it is found in the same position. always on or near a line of strike passing through well 1+0. The break becomes less conspicuous west of well 40. Accompanyirg the rapid increase in dip south of well 140 is a rapid southeastward dying out of the south branch fault. The break in dip may reflect a local hinge line on the east side of the field north of which most of the downward movement along the fault occurred. miteging horizon contains a gentle synclinal nose whise axis » ‘ trends approximately north-south and coincides with the weSt section lines of sections 61 and 63. This synclinal nose 'is not 'Very apparent on deeper horizons. In addition to this syncline. there is another minor syncline. the axis of which lies on a line connecting wells 31 and 37. Between these two synclines is a broad. gentle anticlinal nose. _ Another broad. gentle anticlinal nose is found along the fault in T. 14 S. . R. 5 E.. It parallels the/fault and is continuous from the main east-west trending anticline. 30 W - The Miocene A sand is the next deepest horizon mapped (pls. 3. AA. LI. 5. and 7). It occurs about 11400 feet below the Heteggstegim correlation point. Control available in wells 11. 12. and 16. shows a reversal from south dip to north dip as the fault is approa- .. ched from the south forming an anticline against the fault. The axis of the anticline on this sand is shifted about 800 feet southward from its position onthe overlying-Hgtgggstegim horizon. Because of this shift. control on the anticline is much better on the Miocene A sand. The east end of the anticline is cut off by the fault. and the west end plunges on the east side, of section “1+ thereby forming structural closure of a minimum of 30 feet and a maximum of about 50 feet. 0n the extreme westerne dge of the field. datum points in wells 1 and 2 indicate thatthe contours diverge from the fault. Because the fault has been found barren on all horizons penetrated west of a north- south line passing through well 3. it is likely that there is a lack of closure against the fault westward from that line. A synclinal nose or saddle that divides the closed part of the structure from the open part, occurs between wells 2 and it. This nose is apparent) on all deeper horizons also. The synclinal nose whose axis coincided with the west section line of sections 61 and 63 on the Plate:- magma structure map also occurs bn this horizon. but the nose does not appear to be nearly as pronounced. 0n the Miocene A sand a weakly developed anticlinal nose that is continuous from the main east-west anticline parallels the fault in T. 1+ 5.. R. 5 E.. The contours along section 29. 28. and 33 turn a little more sharply into the fault on this horizon than on the overlying gate;- gm correlation point causing this nose to be more pronounced. This I 31 nose could represent what was once an anticline along the fault in T. 1+ 3.. R. 5 E. Because in T. U, 3.. R. 5 E. the axis ofthis anticline does not parallel the axis of the geosynclins. regional tilting nearly obliterated itleaving only structural nose which now appears along the fault. The nose seems to die out on the break in dip at well 1+0. The dip on the extreme south limb of the anticline is steeper than on the Heterostegmg correlation point. The break in dip on strike with well 40 is much sharper. the dip below the break between wells 1+0 and 1+3 being about 250 feet per mile or about 2°u3' and the dip- above the break beirg about 110 feet per mile or about 1°12'. The imreased sharpness of the break may reflect the formation of structure contemporaneous with deposition. Because structural movement has been taking place over a longer period of time on deep horizons. aw structural feature would generally be expected to become more pronounced with depth. 0n the east side of the field. along the downthrown side'of the south branch fault. in section 3.'control in wells. 1+2 and 1+3 show an upturning of the beds into the fault. "In well 41 there is no indication of upturning. Therefore. upturning must begin between well 41 and well 1+2. and it continues an unknown distance southeastward. Th‘i‘ upturning must represent a local instance of normal drag occurring with downward movement along the fault. Migggg G-h 3m - The Miocene GJ+ sand is found about 725 feet below the top of the Miocene A sand. and it is the next deepest horizon mapped (pls. 3. 4A. 5. and 8). Aburdantcontrol in the northern third of sections 1314 and 61 show a distinct reversal of dip northward into the fault. Like the Miocene A anticline. the anticline formed by dip rever- sal plurges to the west. Unlike the Miocene A structure. the anticlinal 32 high formed by dip reversal is not equally apportioned across sections 4“. 57. 61. and 30. Instead. a saddle on the east side of section 60”, divides the anticline into two separate highs. one centered on the north- ern third of section 61 and the other high probably centered on the northeast corner of section 60. The anticlinal high in section 61 plunges to the west and is cut off by the saddle on the east thereby forming a possible ”0 feet of anticlinal closure. A gentle anticlinal nose t1 ends southward from this high across the eastern sides of sections 61 and 63. The high centered on.the northeastern corner of section 60 cannot be accurately mapped because of limited control. This portion of the anticline may plunge to the east forming some anticlinal closure. or it may close into the fault. It has less area than the section 61 closure and therefore probably less closure. The re-entrant of the 7650. feet contour towards the fault near well 2 gives a total closure some- what in excess of the anticlinal closure in section 61. possibly 50 feet. The axis of the anticline on this horizon is in approximately the same position as on the overlying A sand. It also does not appear to shift much on the underlying horizons. Thus the basic anticline of the structure seems to be very asymmetrical between the upper two horizons and fairly symmetrical on all lower horizons. Control in wells 1 and 2 shows the 7650 feet contour to diverge from the fault again leaving a lack of structural closure against the fault west of a north-south line passing through well 3. A north-south trending synclinal nose occurs betweennwells 2 and ,3 which separates the area of dip reversal to the east from the area to the west where dip IeVersal seems to be lacking. ‘ The saddle or synclinal nose in section 60. which divided the main east-west anticline into two separate anticlinal highs. is found only on the crest of the structure and not on the lower limb. lts relation.- ship to the rest of the structure is difficult to determine. Differen- tial compaction could cause the 7650 feet contour to swing into well 25 after passing the buildup. but would not explain the swing out around well 27 again. Looking at- wells 25 and 26 on plate 18. we: cannot find any variation in thickness that would indicate that differential compac- tion is responsible for the syncline. _If it were due to a local increase in downward movement along the fault on the west side of section 60 or local differential anticlinal uplift. it would have to be reflected on the deeper J sand structure. Looking a\ plate 10. a small synclinal depression is fourd at well 25 on the J sand and although no syncline is shown on plates 11 to 11+. its absence may be due to a slight shift weste ward between points of control. The most likely explanation seems to be locally increaseddownward movement or locally decreased upward movement occurring in part after Miocene G-U deposition. Because it does not appear on the Miocene A sand. the movement ceased before the time of Miocene A deposition. I The anticlinal nose whose axis trends parallel to the fault on a line between wells 35 and 140 in T. 1+ 3.. R. 5 E. is found, again on this horizon. It is much more conspicuous on this horizon than on the two shallower mapping horizons. for the contours on this horizon turn around very sharply into the fault. Control in wells ’42 and 43 on the down- thrown side of the south branch fault again show an upturning of the ° beds into the fault. The upturning may be slightly sharper than the upturning was on the A sand. The fault block formed by the branching of the main fault contains 34 no well control on this horizon. Therefore. the contours are shown as striking in a direction between the'directions found on the shallower Miocene A sand and the deeper Vicksburg lime where control occurs in one well. The local break in dip on strike with well 140 is found again on this horizon. The dip below the break is about 255 feet. per mile, and the dip above the breah is 100 feet per mile if taken slightly westward from the anticlinal nose. Thus a slight increase in the abruptness of the break may occur between this horizon and the overlying A sand. W - The Miocene H sand occurs about 70 feet below the 0.1; sand and is the next deepest mapping horizon (pls. 3. 1m, bl. 5. and \O ). The H sand structure shows a distinct reversal of dip from south dip to north dip as the fault if approached from the south forming an east-west trending anticline along the fault. A saddle between wells 2 and 5 close the anticline on the west. and another one in the east cen- tral part of section 60 divides the anticline into two separate areas of closure. one centered on the northern one-third of section 61 and the other centered approximately on well 29. The anticline in section 61 has the maximum anticlinal closure. about 50 feet. This is the maximum anticlinal closure of all horizons mapped. A rather pronounced anticlinal nose extends southward from the main closure. ' ' Although anticlinal closure centered on well 29 is shown on this map, actual control is limited and whether the 7700 feet contour closes into itself or whether it closes into the fault cannot be determined. There is no doubt that some closure does exist. but the exact amount 35 cannot be determined with the present control. The synclinal nose or saddle in section 141+. closing tl'e structure on the west end. forms about 75 feet of closure into the fault. of which the top 50 feet is anti- clinal closure. The H sand has a pronounced buildup underlying sections 61 and 63 (pl. 19). That the area of greatest anticlinal closure and an associ- ated southward extending anticlinal nose on the Miocene H and 6.4 sands should correspond in position with the H sand buildup seems more than coincidence. Evidently the effects of differential compaction of this buildup. combined with regional tilting. caused an accentuated high and an associated southward trending anticlinal nose to be superimposed on the main east-west trending anticline. The effects of the thickness of the H sand on the amount of closure can be noticed by comparing the greater size and amount of closure of the anticline centered on the northern I one-third of section 61 with the size and closure of the anticline cen- tered on well 29. and by comparing the structure of the Miocene J sand (pl. 10) and the Miocene A sand (pl. 7) with the structure of the Miocene H and 0.1+ sands. The H sand buildup will be discussed more thoroughly when the Miocene H sand isopach map is discussed. . The axis of the anticline on the Miocene H sand is in about the same position as the axis on the overlying 0-“ sand. The difference between the positions of the smaller anticline on the two horizons is probably due more to lack of control and effort to maintainthe same contour spacing than it is to any real change in the position of the anticlinal axis. The anticlinal nose that is continuous from the min east-meet anticline and whose axis runs parallel to the fault on a line running I' 36 between wells 35 and 140 occurs again on this horizon. It seems to be more pronounced on this horizon than on any other. A broad but shallow synclinal trough occurs between the anticlinal nose over the H sand buildup and the anticlinal nose paralleling the fault. It can also be observed on the overlying GJ+ sand. Control in wells 1&2 and 1+3. in section 3 again show a local upturn- ing of the beds into the fault. Again there is no control on the fault block produced by a branching of the fault. and the contours in the fault block are drawn in a position . betwaen their position on the Miocene A sand and their position on the Vicksburg lime where control was available. West of well 2 on the west side of the field. the contours diverge from the fault. The dip below the break in dip at well 140 is essentially the same as on the overlying G-b sand. The‘dip above the break on the anticlinal nose is probably also the same. Anyohange is due to the fact that the contour lines on the H sand map fall on the points of control rather than in positions between the points of control. When the H sand and overlying horizons are compared. it can be noticed that the overall dip on the south limb of the structure is increasing with depth. This is probably due to the effects of geosynclinal submergence contemporaneous with deposition and to anticlinal uplift contemporaneous with deposition. Geosynclinal submergence and anticlinal uplift has affected the deeper horizons for a longer period of time than the shallower horizons; there- fore they have the steepest dip. W - The Miocene J sand is the next deepest blanket sand deposit. It lies approximately 100 feet beneath the top of the '..-.:——w-'-a‘. ~.—————- 37 H sand (pls. 3. 4A. 4, 5. and 10)- It is hard to believe that this sand lies only 100 feet below the H sand, for the J sand shows a complete lack of any significant rever- sal from.south dip to north dip as the fault is approached from the south and therefore a complete lack of large areas of anticlinal clos- ure. Instead. only very small areas of anticlinal closure occur against the fault. such as a small area‘of anticlinal closure that encircles wells 4 and 5. The amount of closure on this local high cannot be determined exactly with the available control. but it is probably less than 20 feet. With the 50 feet contour interval this anticlinal closure . appears only as an anticlinal nose extending southward from well n. Other small anticlinal closures may occur in the northern thirds of sections 60 and 61. Control is not close enough to prove closure there. but con- trol does show a linear zone of flat dip in the northern thirds of these sections. A slight reversal of dip into the fault associated with this flattening could probably be proven if control was found closer to the fault. The axis of an anticline that might occur due to this slight reversal of dip would trend approximately eastewest and bisect the north- ern thirds of sections 60 and 61.- This position is the same as the position of the anticlinal axis of the overlying H sand. At the J sand the fault plane appears to be encroaching upon the axial plane of the anticline leaving very little more than the anti- clinal crest with almost no reversal of dip to produce significant zinticlinal closure. Undoubtedly. the H sand buildup played an important partrin locating and determining the amount of closure on the 6.4 and H sands. Without the buildup. it is likely that these sands would not have tsontained much more closure than the underlying J sand. 38 A small synclinal nose whose axis runs north-south on a line approx- imately coinciding with the west section line of section 61 occurs on ' this horizon. It may be due partially to erosion of a portion of the J sand at the base of the H sand buildup. Just to the left of this nose is another narrowrather sharp synclinal trough also trending north- south occm'ring'in about the same position as it is found in the over- lying H sand. The anticlinal nose that parallels the fault between wells 35 and 1&0 on the GA and the H sands is also apparent on this horizon. and as on the GA and H sands it is quite pronounced. In section 3 the beds again show a local upturning into the down- thrown side of the south branch fault. Because well #1 does not show any upturning. the change in structure occurs between wells 1+1 and 1&2. Again no control is available in the fault block formed by the branching of the fault; hence the'beds are shown to strike in a direc- tion between the strike on the Miocene A sand and the strike on the Vick- sburg lime where there is some control. The maximum dip on this horizon as on other horizons is found below the break which occurs on a line of strike passing approximately through well 1+0. Below the break the dip is approximately 260 feet per mile. Above the break it is difficult to get a straight'line perpendicular to the dip from which the dip may be obtained, but 100 feet per mile would probably be a fairly good estimate. W - The top of the Vicksburg line is the next deepest mapping horizon (pls. 3. 4A. 4,‘5, and 11). It occurs approximately 500 feet below the J sand. All wells drilled for Miocene completion do not. reach the Vicksburg lime and therefore much of the control in the north- ern part of sections ’44. 60, and 61 is lost; 39 On all horizons below the J sand, the structure does not show any significant complete reversal from south to north dip as the fault is approached from the south. and nearly all closure is fault rather than anticlinal. 0n the Vicksburg lime a broad anticlinal nose whose axis trends southward across the east sides of sections 60 and 6+ and another narrower but sharper anticlinal nose trendirg southward across section M are cut off on the north by the fault forming about 70 feet of structural clos- 'ure against the fault in sections 141$, 61, 60 and 30. Between those two anticlinal noses is a very shallow synclinal trough. The synclinal trough trending southwest across the northwest side of section M4 is much sharper on this horizon than on overlying horizons, and it seems to be getting deeper and sharper with depth. 011 the east side of the field the anticlinal nose paralleling the fault on a line coinciding with a line connecting wells 35 and 1+0 is only slightly noticeable on this horizon. Its absence on the map may be due in part to a lack of control in wells 35 and 39. But the little con- trol in all other wells in sections 30, 31.. 29, and 32 does not show any pronounced anticlinal nose. Perhaps the fault plane has. crossed or nearly crossed the axial plane of the anticlinal nose leaving very little evidence of its existence on the overlying horizons. On this horizon as well as on the past four consecutive overlying horizons. control in wells 1&3 and 1+0 in section 3 shows an upturning of the beds into the fault. As on the four overlying mapping horizons. the upturning of the beds is not apparent at well 1&0. The structure is prob- ably due to a local occurrence of normal drag associated with normal faulting. On this horizon we again have control in one well on the fault block produced by a branching of the fault. When the control in well 41 is tied in with the necessary displacement across the fault. it becomes necessary to have the contours strike in a north-northeast direction. ' This horizon has the steepest dip of any horizon mapped. South of well 40 the dip is 330 feet per mile. or over 3055' and above the break in dip it is about 160 feet per mile or about 1°w. This is notice- ably steeper than any of the deeper horizons and is not what would be expected. The change in dip at the break is about the same on this horizon as on the overlying Miocene J horizon. The only explanation offered for the anomalously large dip is that the top of the Vicksburg line must rise stratigraphically in a northerly direction. A northward rise in the stratigraphic position of the Vicksburg lime. rather than an uncomformity. may explain the northward thinning of the shale inter- val overlying the Vicksburg lime and underlying the Chickasawhay (See the discussion of the age of the Chickasawhay in the stratigraphy section on page 18). Mo B — The top of Moodys Branch marl is the next deepest mapping horizon. It lies approximately l+50 feet beneat the top of the Vicksburg lime (pls. 3. in. u, 5, and 12). ' This horizon shows no complete northward reversal of dip into the fault. but it has 125 feet of fault closure formed byt he intersection of two anticlinal noses with the fault. a broad north-south trending anticlinal nose whose axis runs across the east sides of sections 60 and 61*. and a smaller but sharper anticlinal nose whose axis strikes northeast and approximately coincides in position with a line connecting 1:1. wells 3 and 9‘. The smaller nose seems to be more pronounced on this horizon than on shallower horizons probably because the syncline between wells 2 and 3 is becoming slightly sharper with depth. The significance of this sharp anticlinal nose is that it indicates some local reversal of dip into the fault in sections M4 and 61 may have occurred on this horizon between the time of Moodys Branch marl deposition and the time of deposition of the tap of the Vicksburg lime. The larger nose is. also ' becoming pronounced with depth thereby adding to the area of closure. A broad and gentle synclinal nose occurs between the two anticlinal noses. West of well 2 the contours diverge from the fault as they have on shallower horizons. The anticlinal nose which parallels the fault between wells 35 and #0 on shallower horizons is only very slightly apparent. and it appears as though the axial plane of this nose has crossed the plane of the fault. On Moodys Branch marl a broadening of the contours between wells 35 and 1&0 seems to reflect. the beginning of a structural'terrace found on the underlying Cockfield B sand (pl. 13). It would even be possible to contour a small closure in the northwest corner of section 33 showing a slight development of the terrace. The upturning of the beds into the fault whichwas found on the Miocene J sand and the Vicksburg lime in section 3 is not noticed at this horizon. Evidently the cause of the upturned beds affected only the Vicksburg lime through Miocene A horizons leaving those below and those above only slightly disturbed. The overall di‘p on the south limb of the structure on the Moodys, Branch marl is much gentler than on the overlying Vicksburg lime. but slightly greater than on all other shallower 11,2 horizons. Because of the spreading of the contours along the fault. the dip above the break at well 40 is difficult to determine; 120 feet would probably be a good approximation. Below well no it is approxim- ately 265 feet per mile. Qpplgfield B Sang - The tOp of the Cockfield B sand is the next deepest mapping horizon. It occurs approximately 350 feet below the top of Moodys Branch marl (p18. 3. “A. 1+. 5. and 13). On the Cockfield B sand there is no great northward reversal of dip into the fault. However. datum points in wells 27 and 28 possibly indi- cate a small area of dip reversal and anticlinal closure on the east side of section 60. If closure exists it would only amount to a few feet. The contours turn around sharply into the fault in section 141+. as they did on the Moodys Branch marl structure map. forming an anticlinal nose and an adjacent sharp synclinal nose. The structure seems to be the south limb of an anticline whose axial plane and the fault plane intersect approximately at the Cockfield B horizon leaving only the south limb of the fold appearing on the downthrown side of the fault. Because the strike of the fault plane is slightly northwest from the strike of the axial plane of the basic anticline. the anticlinal axis lies across the fault onthe east side of the field. and a well :bveloped nose occurs in section M4 on the west side of the field. As on the two overlying horizons. the south limb of this proposed anticline may be broken into two anticlinal components. the anticlinal nose in section 141+ and the broader anticlinal nose whose axis trends north-south along the west section line of sections 60 and 6+. These two anticlinal noses are sepa- rated by a minor synclinal trough thus forming two separate highs against the fault. The fault closure formed by the intersection of the fault and the two anticlinal noses is at leadt 130 feet and is as great as the closure on the Moodys Branch marl. The very sharp syncline which trends southward from well 2 just to the left of the anticlinal nose in section #4 is found again on this horizon. It provides the re-entrant into the fault whichrclosed the structure on the west side. ‘Westward from this re-entrant. the structure opens as it has on all other horizons. On the east side of the field gentling of the dip. which was first observed on the Moodys Branch marl structure between wells 34 and 36. is even more pronounced. It has developed into a structural terrace centered on the northeastern corner of section 32. The terrace and its significance will be discussed more thoroughly in the discussion of the Cockfield D sand structure. ‘well #2 is faulted at a depth of 9479 feet. The Cockfield B sand is not reached at this depth and is faulted out. This means that if well #2 were unfaulted. the Cockfield B sand would occur at a depth below _9479 feet. Since well #3 has a datum of 9b55 feet. the contours must turn sharply northward at the fault showing a downbending of the beds into the fault on this horizon. Evidently the forces of deformation along the south branch fault in section 3 changed considerably between preéhoodys Branch marl time and postJVicksburg lime time. because the attitude of the beds along the south side of the fault on the Vicksburg lime opposes the attitude of the beds against the fault on the Cockfield B sand. Limited control in the fault block on the east side of the field gives the beds a strike northeast of their strike on the south side of the south branch fault. The break in dip occurs again on this horizon. Because of the slight nu change in the contour pattern caused by the structure terrace, the sharp- ness of the break in dip is not as apparent on this horizon as on shallower ones. Below the break in dip the dip is 270 feet per mile. This sub- stantiates an increase in dip with increasing depth. Cockfield.DH§agj - The top of the Cockfield D sand is the deepest horizon mapped. It occurs approximately 150 feet below the B sand (tfls. 3. hA, Q, 5. and 1h). Because of the fault in well 2. well 2 does not afford any control on this horizon. Therefore the exact amount of closure into the fault cannot be accuratelycietermined. Using the control available it would be possible to map this horizon almost the same as the overlying Cock- field D horizon, giving it about the same amount of’closure. As on the B sand most of the structural closure is provided by the intersection of the basic anticline and the fault. Also as on the B sand, the basic anticline can be broken into two structural roses. the smaller southwest trending one in section Mn. and the broader one whose axis trends southward approximately coinciding with the range line on the east side of sections 60 and 60. As on the B sand a small area of dip reversal and anticlinal closure may occur on the larger anticlinal nose along the fault in the east central part of section 60. Notice that the 9250 feet contour on the Cockfield D horizon and the 9100 feet contour on the Cockfield B horizon pass about the same distance south of well 23. but that the 9250 feet contour on the D liorizon is considerabfly'closer to well ll than the 9100 feet contour is on the B horizon. The Cockfield B sand buildup underlies the central 'part of section 61 and eastern part of section.hh. It is probable that exists between the elastic highs in the northern part of sections 60 and 61 and - the anticlinal high of the structure. The increase in coarse clastics probably reflects a northward regional increase with little or no local structural influence. Apparently the anticlinal high was only a prom- inent enough feature toeaffect the distribution of coarse clastics. A linear area of low sand is found which trends northwestward and passes from the southwest corner of section 61. T. U S.. R. MUN. to the southeast corner of section 1. T. 5 S.. R. 4 E. This zone of low sand content lies eastward of a syncline on the Miocene A and Hetergstggina structure maps (pls. 6-7) and can be noticed trending north-south along the west section line of sections 61 and 63. T. h 5.. R. h E. The syn- cline also has a trend which is oblique to the low sand zone. Therefore. there is probably no relationship between the synclinal nose and this zone of low sand content. In conclusion. it seems that no conclusive relationship>can be found between.the sand-shale ratio and the structure. Apparently the structure was never a positive enough feature on the sea floor to affect the dis- tribution of coarse clastics. 88 GEOIDGIC HISTORY OF THE WASHINQ‘L‘QN FELQ Assuming that the structure is salt cored. the history of the Wash- ington field would begin with the deposition of the Louann salt bed. which is believed by many to be of Louann or Upper Permian age (Halbouty and Hardin. 1956). Following theoeposition of the salt. the sediments of the Triassic. the Jurassic. the Cretaceous. and the Midway of the lower Eocene were deposited. This brings us to Sabine time When the Wilcox was deposited. During the time of Wilcox deposition. the sea was regressing; and the Washington field area lay within a deltaic and marginal marine environment. Fine to medium grained sands and interbedded lignitic shales were deposited during this time. Following the regression of the Wilcox and possibly a period of erosion. the seas of Claiborne time advanced into the area depositing the basal Cane River marl and then the Cane River clays and nude as the strand line advanced farther northwmd. The fact that the Cane River in well 28 on the upthrown side of the fault is 55 feet thinner than well 23 less than a mile away on the downthrown side may indicate that the salt had started to move upward by the time of Cane River deposition arching the strata and causing faulting. As Cane River deposition came to a close. the seas began to regress. and the regressive near shore probably shallow water calcareous sands and interbedded shales of the Sparta were deposited. After Sparta deposition. there was a rapid transgression of the sea that deposited the basal sandy marl known as the Cook Mountain marl or the Sparta lime. As the area became inundated. the calcareous mudstones and clays of the Cook Mountain shale were deposited. Because the fault has 80 feet more throw in the Sparta than in the Cockfield. the fault probably moved at least 80 feet during the interval of time between the beginning of Sparta deposition and the end of Cockfield deposition. It is probable that this movement was gradual. and it occurred all through Claiborne time. Gradually. the strand line shifted Gulfward; and the marginal marine sands and shales of the Cockfield were deposited. At sometime previous ' to Cockfield B deposition. the structural movement forming the terrace in section 32. T. h 8.. R. 5 E. on the Cockfield B and D horizon began. This movement continued until the beginning of Jackson deposition. There is some evidence that it may have started again Just after the deposition of the Vicksburg lime. During Cockfield time local sluinping of beds into the fault took place in section 3. This slumping into the fault could have been associated with anticlinal uplift. A thicker deposition of. Cockfield sediments in the depression filled it as fast as it formed. Local downward movement also occurred against the fault in sections 60. 30. and 39 during the Cockfield. The depression created was filled by thicker sediments contemporaneous with the formation of the depression. Anticlinal uplift centered on the northwest corner of section 31 accom- panied and perhaps caused the adjacent downbending of beds into the fault. This uplift formed the large anticlinal nose occurring in sections 60 and 30 on the Cockfield B and D horizons. Thirty to forty feet of Cockfield thinning in well 39 on the upthrown side of the fault indicates that at least 30 to #0 feet of fault movement occurred along section 33 during Cockfield deposition. A difference of 60 feet in throw of the fault in wells 5 am 16 indicates that over 60 feet of movement along the fault 90 in sections 60. 61. 57. and #4 occurred between the time of Cockfield deposition and Miocene H sand deposition. Because the thinning across the fault is rather uniform. the movement of the fault was continuous and uniform rather than periodic. During the time of Cockfield D depo- sition some stream or other source supplied sand to the east side of the ‘Washington field. The sand was apparently distributed as a blanket sand tw-wave and current action along a regressing or transgressing strand line. During Cockfield B deposition. flhe field area was again on or near the strand line. This time the mouth of a stream or some other source of sand was located on the west side of the field. Evidently the field area was subsiding quite rapidly at this time and sand. after being car- ried out into the Gulf by the current source. never remained exposed to currents and waves long enough to have a large eastpwest distribution. During Cockfield B deposition. a regression or transgression of the strand line was occurring. and it gave'the sand its present north-south.distri- bution. At the close of Cockfield deposition. the early Jackson sea trans- grossed rapidly depositing the basal Mbodys Branch marl formation which was followed by the Yazoo shales as the area became inundated. Towards the end of Yazoo deposition. a gradual change in the environment occur- red. Apparently the supply of clastics dwindled, and a larger proportion of lime was deposited with the sediments. By the time of Vicksburg lime deposition. the sediments had become very limy.t During Jackson and Vick- Sburg deposition a slight local downward movement occurred along the fault in sections #4. 57. 61. and 60. A corresponding very'small anticlinal uplift occurred in the southern portion of section 60 forming the main north-south trending anticlinal nose occurring in sections 60 and 30. f 91 In addition there is a possibility that the southwest trending anti- . clinal nose in section M4 was also forming. In section 3. local rever- sal of dip into the fault continued during Jackson time and may or may not have continued into the time of Vicksburg deposition. The uplift which formed the section 32 terrace of the Cockfield B arr! D sands was inactive during the time between deposition of Moodys Branch marl art! the deposition of Vicksburg lime. In section 33. the fault was much less active than during the time between the deposition of the Cockfield D sand and the Moodys Branch marl. The syncline which trends southwest- ward from well 2 was apparently forming during Vicksburg and Jackson time. and it may have been forming during the deposition of the Cockfield. This movement probably continued through Miocene A deposition. After Vicksburg line deposition. rapid changes in the environment of deposition took place. More clastics were supplied to the area. and more rapid deposition took place with an abrupt decrease in lime. The sea began to regress and it never again made a major transgression into the Washington field area. The Vicksburg shale was deposited followed by the marginal marine sands and shales of the Chickasawhay. Movement along the fault on the north-central part of the field was quite pron- ounced during the deposition of the Vicksburg shale and the Chickasawhay ' formation. At least 1+0 feet of fault movement took place along section 60 and 61 between the time of Vicksburg lime and Miocene H deposition. After deposit ion of the H sand. the amount of fault movement during a given interval of time cannot be determined because of a lack of control on the fault plane and on the upthrown block of the fault. A number of blanket 'sands were deposited during the Chickasawhay. The Miocene H and J sands are two'such sands. and they probably represent 92 strand line deposits. During the deposition of the Miocene H sand. the strand line was on or near the Washington. field. A stream or tidal channel entered the field area from the north. The channel or stream had strong currents that eroded much of the underlying shale. The depres- sion created by erosion was filled with sand carried in by the current or by wave action on the flanks of the depression. Contemporaneous with deposition in the channel. the thinner Miocene H blanket sand was being deposited across the field by wave and current action along the shifting strand line. Shortly after deposition. the beds overlying the sand were arched into a structural high by greater compaction of the shale surroun- ding the buildup. By the time the Miocene A said had been deposited. thinner deposition over the buildup had masked the effects of differen- tial compaction. The Washington field area remained near the strand line during the ' deposition of the Frio. and a deltaic and marginal marine environment persisted. Many of the sands deposited were massive and deltaic; how- ever the Miocene l sand seems to be a blanket deposit. The sands were separated by marine shale. The environment during Frio deposition seemed to have ben more deltaic than the preceding Chickasawhay environ- ment. Anticlinal movement or uplift across sections “1+. 61. 60. and 30 was taking place during the tine between Vicksburg lime and Miocene A deposition. Evidence of anticlinal uplift is much greater during this period of deposition than during the Cockfield through Vicksburg lime period. Accompanying the anticlinal uplift there was a corresponding reversal of dip into the fault. While anticlinal uplift and reversal of dip were occurring. they were being compensated for by thinner depos- ition over the high and thicker deposition in the low‘ against the fault created by dip reversal. Anticlinal uplift along the fault in T. 1+ S.. R. 5 E. was not very pronounced during the time that the interval Vicks- bm'g to Miocene A was deposited. The only evidence of uplift occurs in section .32. The syncline which divides the anticline into two highs was also formed during the deposition of this interval. This movement stopped by time of Miocene A deposition. am! it was masked by thicker sedimentation in the syncline area. Somtime after the deposition or'noodys Branch marl and before the deposition of the top of the Miocene J sand. a dragging movement began to take place along the fault in section 3. This dragging movement effected the Moodys Branch marl beds. which previously had bent down into the fault. The dragging movement continued through Miocene A deposition. but it died out by the. time of Hetezgstegigg deposition. A thinning of the Frio am Anahuac sediments over the dragged beds blotted out the structure so that it does not appear on the Wm corre- lation point. After Miocene H deposition at least 2140 feet of movement occurred alorg the fault. How the movement is spaced through the interval of time between the time of Miocene H deposition and Recent time cannot be determined in this report. It could be possible that movement is still occurring at a very slow rate (meets. 191W). and a thinning of the Mississippi River flood plain deposits over; the structure does not allow a topographic feature to develop on the surface. Following the deposition of the Frio format ion the more marine Anahuac formation. which includes the We paleontological zone. was deposited. For a brief time during W deposition marine ‘94 conditions prevailed in the Washington field area. and limes were depos- ited. Gradually conditions became deltaic again. and the upper Cata- houla to Recent sediments were. deposited in a predominantly deltaic environment. During the time between Vicksburg lime and Hgtem§teging deposition. anticlinal uplift and associated downbending of beds into the fault occurred along the fault from at least as far west as well 2 to as far east as well 41 forming the anticline and associated anticlinal nose. which together are continuous along the fault from well 2 to well no on the Miocene horizons. Subsequent regional tilting caused the por- tiOn of the anticline along the fault in T. it 3.. R.5 E. to be destroyed leaving as a remnant an anticlinal nose paralleling the fault. The anti.- clinal uplift along the fault continued until after the time of Bitm- ’ stegma’ deposition. possibly up to the present. Sedimentation was con- temporaneous with the formation of the structure. and any given layer of sediments thinned over the highs and thickened in the lows along the fault masking all structural movement occurring prior to its deposition. Contemporaneous with the developnent of the salt cored faulted anticline of the Washington field. there was more or less continuous regional tilting towards the Gulf causing each deeper stratigraphic unit to have greater south dip. When the branching of the fault occurred cannotbe determined in this report. Fairly good control occurs on the south branch fault. and movement appears to have been continuous on it throughout the time be- tween deposition of the Cockfield D sand and deposition of the Mg- stggina correlation point. Movement on the south branch fault cannot be thoroughly studied because of a lack of control. However. at least 80 to 100 feet of movement occurred after deposition of the Miocene H sand. 95 PRGJUCTIO! Two zones of production occur in the Washington field. There are the deep Cockfield sands which produce gas and condensate and the shal- lower Lower Miocene (7) Chickasawhay formation. more commonly knowna the Nodosarig zone. which produces oil. Gas and condensate are produced from two sands in the Cockfield. the Cockfield B sand on the west side of the field and the Cockfield D sand on the central and eastern side of the field (pls. 3-5. 13. 1'4. 21. 22. and 21+). The producing zone for the Cockfield D sand is from 9178 to 9608 feet. In comparing the area of production of the Cockfield D sand (pl. 24) with the structural closure of the D sand (pl. 114). the produc- tion occurs far below the deepest structural contour closing into the fault. This is explained by the fact that hydrocarbons in the Cockfield D sand are trapped by a combination stratigraphic and fault trap. The hydrocarbons are trapped on the west by a pinchout (pls. 4A. 5. and 22) and on the north and east by the fault (pl. 11+). The producing zone for the Cockfield B sand is from 9036 to 9100 feet. The Cockfield B reservoir is a fault trap. All of the hydrocarbons lie within the clos- ure formed by the intersection of the fault and the south limb of the anticline of the structtme. Production is limited slightly on the east by a pinchout (pls. ”A. 5. 13. and 21) along the east sides of sections 60 and 614. The average gravity of the condensate from the Cockfield B and D sands is 60° API. The W zone contains at least five yroducing sands in the Washington field. They are: the Miocene E sand producing from 7280 to 7320 feet. the Miocene I" sand producing from 71nd to 7““? feet, the 96 Miocene 6-3 sand producing from 7573 to 7605 feet. the Miocene H sand producing from 7652 to 7680 feet, and the Miocene J sand producing from.777h to 7799 feet. The H sand also produces from 779h to 7804 feet in.a small area in section 29 (pl. 23). The oil in the Egdgsggig zone generally has a gravity ofoabout “0° API. Oil in the Egdgsggig,sands is trapped primarily by local areas of anticlinal closure in sections 4h. 57. 61. and 60. The H sand trap in section 29 may also be a small isolated area of anticlinal closure. All of these sands have producing areas of less than 300 acres. but taken together they constitute a rather significant amount of production. In addition to these five sands. there are a number of other sand stringers in the Ngggsarig zone which have oil shows on the anticlinal highs in sections 60 and 61. The total proven area of oil and gas production in the‘Washington field was 2640 acres at the end of‘l957. Cumulative production through 1957 is as follows: oil and condensate 1.831.323 barrels gas (dry and casinghead) 3.39“.377 HCF. 97 momgumnons This study of the Washington field has shown a number of new pros- pects for oil exploration. One prospect is the mm zone in the fault block on the east side of the field. Looking at plates 6 to 11+. one can see that the fault block has plenty of structural closure. but that no walls have penetrated the W zone within the block. Because the Ngdgsarig zone has proven so productive in sections “1+. 60. and 61. it should be worthwhile to drill a Nodosaria zone test centered on the southeast corner of sec- tion 34. T. ’4 S.. R. 5 3. Two other prOSpects are related to two potential producing zones lying below the Cockfield. One of the potential zones is the Sparta sands lying between a depth of 10 .160 and 10.5% feet in well 23 and the other is the Wilcox sands beginning at a depth of 11.468 feet and continuing down an unknown distance. possibly as great as l+000 to 5000 feet. // Petroleum from the Sparta sands is being produced from the Pine Prairie. Ville Platte and Redell fields in Evangeline Parish. slightly updip from the Washington field. In St. Landry Parish Melville field. which is on strike with the Washington field. and the Opelousas. Port Barre. and Bayou Courtableau fields. which are downdip from the Washing- ton field. produce from the Sparta. In the Washington field wells 1. 23. 26. 28. 39. am 1+0 have pene- trated the Sparta without encountering petroleum. These wells show that individual sands of the Sparta in the Washington field can be carried across the field and indicate that the sands are blanket marine or 98 marginal marine deposits. which should make them ideal as oil reservoirs provided that they have sufficient porosity. A rather low spontaneous potential on the electric log combined with a deep mud water invasion indicate that the sands are rather tight (Schlumberger Document No. it. 1950). However. if they produce on strike arr! downdip from the Washing- ton field they may also be capable of producing at the Washington field. Considering the wells which penetrate the Sparta at the Washington field. we find that well 1 is on the west side of the field where no production has been found on em other horizon probably because of a lack of closure against the fault. Wells 39 and 140 penetrate the Sparta on the upthrown side of the fault and are probably structurally low on any anticline which might occur on the upthrown side of the fault (see salt ridge hypothesis in the section on "The Origin of the Structure"). Inwell 28 all but the deepest two sands of the Sparta arefaulted out. .The Sparta in well 26 lies wholly on the downthrown side of the fault in a position that should be near the structural high. if the position of the structural high did not change considerably frat its position on the Cockfield sands. Using a resistive kick on the Sparta’lime. a datum of 9845 is obtained in well 26 and a datum of 9842 in well 28. These datum points would indicate that the area of closure on the Sparta lies slightly to the west of the Cockfield B and D closure. Before the Sparta can be given upas a possible producer on the downthrown side of the fault in the Washington field. another well should be drilled in a position midway between wells 14 and 15. Also. assuming that the salt ridge hypothesis applies. a second Sparta prospect lies on the upthrown side of the fault in the northern thirds of sections 60. 61. and 30 and the southern parts of sections 58 and 59 and 19 where ant iclinal closure would be expected to occur at the depth of the Sparta. Additional exploration also needs to be carried out in the Wilcox. Only wells 23 and 28 have reached the Wilcox. Well 23-is on the down- thrown side of the fault and it penetrates 1000 feet of Wilcox. The section penetrated contains numerous sands interfingered with shales. The sands are very resistive. The high resistivity is possibly due to ' a deep mud fluid invasion which would indicate that the sands are quite tight. Sands in the upper Wilcox produce hydrocarbons in the Melville and Palmetto fields just to the east of the Washirgton field in St. Landry Parish. Because these fields are as far downdip as the Washing- ton field. one would think that the Wilcox sands in the Washington field should also be capable of producing. The upper part of the Wilcox in well 23 is about 2200 feet south of the fault. hploration in the upper part of the Wilcox should be continued a little closer to the fault in sections 60 and 61 because the area of closure on the downthrown side of the fault at the depth of the Wilcox is apparently rather small. Murray (1952) says that the sands in the upper part of the Wilcox are lenticular. and those of the lover part are more widely distributed blanket sands. In Beauregard and Allen Parishes. on the west side of Louisiana. the lover Wilcox was found productive in the Doornboss McPherson "N" Well #1 from a depth of 14.530 to 14.573 feet in the Burrit- ‘cane Creek field. The initial production was 1.188 barrels of oil per day. This would indicate that it might pay to explore the lower Wilcox as well as the upper Wilcox at the Washington field. It would probably be necessary to drill 2000 or 3000 feet deeper into the Wilcox to depths between 14,000 and 15 .000 feet in order to reach the lower blanket sand zone. Closure on the lower Wilcox sands on the downthrown side of the N 100 fault would be expected to occur in the northern halves of sections 63 art] 64. Well 23 penetrated only about 300 feet of the Wilcox on the up- thrown side of the fault. An unconfirmed show of gas was reported in this well (Sohio Petroleum Company scout book). Because a strong possibility of closure on the upthrown side of the fault exists according to the salt ridge hypothesis. because there may have been a. possible show of gas in the Wilcox. and because the Wilcox on the upthrown side of the fault has. not been explored. the entire Wilcox section as well as the Sparta. should be explored on the upthrown side. of the fault. Accor- ding to the salt ridge hypothesis. the anticlinal closure on the Wilcox on the upthrown side of the fault sl'nuld even be greater than on the Sparta because it lies at a greater depth. Exnloration in the Wilcox on the upthrown side of the fault should be carried out .in the northern thirds of sections 60 and 61 and the southern thirds of sections 58.and 59 where the anticlinal closure wouldbe expected to occur. The Hurri- cane Creek field in Beauregard and Allen parishes Louisiana has a struc- ture very similar to the structure of the Washington field. The prev- iously mentioned Doornboos McPherson ”N" Well #1 produces from the up- thrown block of the min east west fault. This should be additional incentive for testing the Wilcox on the upthrown side of the fault in Washington field. In conclusion the following three areas are recommended for explor- ation: shallow W zone exploration in the fault block on the east side of the field: deep Wilcox and Sparta exploration against the fault on the downthrown side in sections 60. 61. 63. ard 64; and deep Sparta and Wilcox exploration in sections 60. 61. 58. ani 59 on the upthrown 101 side of the fault. Because there is a chance for lower Wilcox produc- tion. the lower as well as the upper Wilcox should be explored. 102 SUMMARY AND CONCLUSIONS In tin Washington field the sediments penetrated by the drill range in age from those of the Eocene Wilcox group to those of the Recent Miss- issippi River flood plain. Thedeepest well is the discovery well which! has a depth of 12,505 feet and penetrates 1000 feet into the Wilcox. The structure at the Washington field is an east-west trendirg anticline with proven closure on the downthrown side against the upthrown side of a down-to-the-coast. east-west trending normal fault. The fault dips 16° south. A given stratigraphic interval shows a rather uniform. thinning on the upthrown side of the fault. The fault also increases in throw with depth. Both of these characteristics indicate that fault- ing was contemporaneouswith deposition. The fault has its maximum amount of throw along the field. Eastward and westward from the field the throw decreases. oh the east side of the field the fault splits into two main branches. one on the north trending east-southeast ani one on the south trending southeastward. The south branch seems to pinch out rather abruptly in a southeastward direction. Another fault of small throw may occur about taro thousand feet north of the north branch fault. Reversal from a south dip to a north dip as the fault is approached from the south downthrown side is found~ on all horizons from the Miocene J sand through the W correlation point. of these five hori- zons only the Miocene H and G-Lt horizons have a large amount of anti- clinal closure. Proven anticlinal closure is 1+0 to 50 feet on these two horizons and is centered in the northern third of section 61. The Miocene A sand. the Miocene J sand and the Hetergtegina correlation 103 point may have a few local areas of small anticlinal closure. Nest of the closure on the Miocene A horizon is formed by the intersection of the anticlinal axis and the fault on the east and the plunging of the anticline on the west. Although reversal of dip occurs on the flgtgzg- stegina horizon forming an anticline along the fault, closure is not proven. Anticlinal development continues to an unknown elevation above the Hetezgstggiga horizon. 0n the west side of the field on the Miocene horizons. an anticlinal nose that is continuous with the main east-west anticline parallels the fault. This nose together with the east-west anticline in sections 4“. 60. and 61 probably represent continuous anticlinal development along the fault between wells 2 and #0. Because the axis of the anticline in T. 4 5.. R. 5 E. did not parallel the regional strike. this portion of the anticline was destroyed by regional tilting. leaving as a remnant an anticlinal nose. 'With the exception of the Cockfield B and D sands. all closure below the Miocene J sand is caused by the intersection of the south limb of the anticline with the fault.‘ The Cockfield horizons may show a small amount of dip reversal and anticlinal closure centered on section 60. Structural closure against the fault is a minimum on the Miocene J horizons and increases to about 125 feet on the “bodys Branch marl. Cockfield B and Cockfield D horizons. The Sockfield D sand is apparently a. blanket sand. strand line deposit which pinches out away from its source. The pinchout on the west side of the structure is very important because it increases clos- ure many times over the amount of closure on the structure map of the sand. 10h The Cockfield B sand probably is a strand line deposit also. This -sand occurs as a linear. north-south trending buildup and it apparently is related to a single source of-sand to the north. The sand was prob- ably deposited on a rapidly submerging sea floor by south flowing cur- rents. Regression or transgression of the strand line gave it its present north-south extent. In addition to submergence. erosion may play a part in the origin of the buildup. Differential compaction of the Cockfield B sand effects the structure on the B sand by causing sections 61 and h# to be at a relatively higher structural position on the B sand than on the D sand. The Miocene H sand is a blanket deposit on‘which a linear. north- south trending. heart-shaped buildup has been superimposed. The buildup seems to be related to a deep tidal channel on the north side of the field out of which flowed a strong current. The current eroded a deep depression in the underlying unconsolidated muds. A thick deposit of sand was deposited in this erosional depression while a thinner blanket deposit was deposited on the flanks of the depression.’ The two thick lobes on the north end of the buildup probably represents two positions occupied by the channel or the positions of two different channels. Differential compaction of the H sand had rather strong effects on the' structure. on the Miocene H ard G-u horizons differential compaction caused a pronounced area of anticlinal closure to stand out on the crest of the anticline over the axis of the buildup. Differential compaction also formed a structural nose extending southward over the axis of the buildup. Most production from'thefiiocene sands comes from the anti- clinal closure formed by differential compaction of this buildup. The little evidence available below depths of 10.000 feet show that~ 105 faulting had probably begun prior to the time of Sparta deposition ard continued an unknown period of time after deposition of the Heterostggmg horizon. A thinning of the stratigraphic interval over the anticline shows that anticlinal uplift had begun before Miocene A time and con- tinued until after Miocene A time. The thinning also shows that since the time of deposition of a given interval regional tilting has shifted the anticlinal axis northward. Due to deposition contemporaneous with anticlihal formation each horizon shows only the movement occurring after the deposition of that horizon. Therefore. anticlinal uplift or apparent uplift continued after deposition of the W horizon. The "salt ridge hypothesis” is proposed as a theory for the origin of the Washirgton field structure because it can explain the main fea— tures of the structure and because it can explain a gravity minimum over the field. The hypothesis was proposed by Quarles (1953) and is stated as follows: "Deep seated vertical intrusions of salt in the form of long narrow ridges push up the Gulfward dipping sediments along their strike to form deep seated anticlines. A pattern of normal faults with 1+5 degree dip has to develop on every ant icline as the adjustment for the vertical forces involved.” According to this hypothesis the anti- clinal crest is on the downthrovm side of the fault on shallow horizons and on the upthrown side on deep horizons. Oil production at the Washington field is from five sands in the Chickasawhay formation (31953915515 zone). The oil in these sands is trapped mainly by anticlinal closure in sections 111+, 50 an! 61. The maximum oil column in any of the W sands is 30 feet. Gas and cordensate is produced from the Cockfield B ani the Cockfield D sands. The Cockfield B sand has a rather small area of production along the 106 fault in sections nu, 50, and 61. The trap for the B sand hydrocarbons is a fault trap. The Cockfield D sand has a very large area of produc- tion covering the entire western three fourths of the field. The trap of this sand is a combination of a pinchout and a fault trap on the north and on the east. ' . The following three areas are recommended for exploration: l. The Maria zone in the fault block on the east side of the field. 2. The Wilcox and the Sparta sands along the fault on the downthrown side. 3. The Wilcox and the Sparta on the upthrown side on the anti- clinal closure which is expected to occur on the upthrown side of the fault at great depth.‘ 107 EIBLIOGEAPHY Bates. Fred we 1938 (and Bornhauser. Max) Geology of Tepetate Oil Field. Acadia Parish. Louisiana. Bull. Am. Assoc. Petr. Geol.. vol. 22. no. 3. pp. 285-305. 1941 Geology of Eola Oil Field. Avoyelles Parish. Louisiana, Bull. Am. Assoc. Petr. Geol.. vol. 25. no. 7. pp. 1363-1395. 1948 (and Wharton. Jay B.. Jr.) Geology of West Tepetate Oil Field. Jefferson Davis Parish. Louisiana. Bull. Am. Assoc. Petr. Geol.. vol. 32. no. 9. pp. 1712-1727. Bornhauser. Max 19+? Marine Sedimentary Cycles of Tertiary in Mississippi Embayment and Central Gulf Coast Area. Bull. Am. Assoc. Petr. 6901.. vol. 31. no. 1A. pp. 698-712. 1950 Oil and Gas Accumulation Controlled by Sedimentary Facies in Eocene Wilcox to Cockfield Formations. Louisiana Gulf Coast. Bull. Am. Assoc. Petr. Geol.. vol. 31+. no. 9. pp. 1887-1896. ' ’ 1958 Gulf Coast Tectonics, Bull. Am. Assoc. Petr. Geol.. vol. 42. no. 2. PP. 339-370. Culbertson. J. A. 1940 Downdip Wilcox (Eocene) of Coastal Louisiana and Texas. Bull. Am. Assoc. Petr. Geol.. vol. 21+. no. ll. pp. 1891-1922. Currie. John B. 1956 Role of Concurrent Deposition and Deformation of Sediments in Development of Salt Dome Graben Structures. Bull. Am. Assoc. Petr. Geol.. vol. 40. no. 1. pp. 1-16. Echols. Dorothy Jung l9ll8 (and Malkin. Doris S.) Marine Sedimentation and Oil Accunulation. I! Regressive Marine Overlap and Overlap-offlap. Bull. Am. Assoc. Petr. Geol.. vol. 32. no. 2. pp. 252-261. Fisk, Ho N0 191?? Fine Grained Alluvial Deposits and Their Effects on Mississippi River Activity. vol. 1. Miss. River Com.. Waterways Experiment Station. 82 pp. 1954 (with McFarlan.E .. Jr.; Kolb. C. 2.; and Wilbert. L. J.. Jr.) Sedimentary Framework of the Modern Mississippi Delta. Jour. Sed. Petrology. vol. 21+. no. 2. pp. 76-99. 108 Haeberle. Fred R. 1951 Relationship of Hydrocarbon Gravities to Facies in Gulf Coast. Bull.-Am. Assoc. Petr. Geol.. vol. 35. no. 10. pp. 2238-2248. Halbouty . Michel T. 1956 (and Hardin. George 6.. Jr.) Genesis of Salt Domes of Gulf Coastal Plain. Bull. Am. Assoc. Petr. Geol.. vol. ’40. no. 1+. pp. 737-746. Howe, H. v. 1933 Review of Tertiary Stratigraphy of Louisiana. Bull. Am. Assoc. Petr. Geol.. vol. 1?. no. 6. pp. 613-655. Lowman. S. W. l9’+9 Sedimentary Facies in Gulf Coast. Bull. Am. Assoc. Petr. Geol.. vol. 33. no. 12. pp. 1939-1997. Murray. G. E. 19+? Cenozoic Deposits of Central Gulf Coastal Plain. Bull. Am. Assoc. Petr. Geol.. vol. 31. no. 10. pp. 1825-1950. 1952 (with Bough. Leo w. and Holland, Wilbur c .) Geology of Beauregard and Allen Parishes. Louisiana. La. Dept. of Cons.. Geol. Bull. 279 2214’ PP- 1955 Midway Stage. Sabine Stage. and Wilcox Group: Bull. Am. Assoc. Petr. 68010; V01. 37: n0. 5; pp. 671-6960 ' Nettleton. L. L. 1955 History of Concepts of Gulf Coast Salt Dome Formation. Bull. Am. Assoc. Petr. Geol.. vol. 39. no. 12. pp. 2373-2383. Price. W. Armstrong 19“? EQuilibrium of Form and Forces in Tidal Basins of Coast of Texas and Louisiana. Bull. Am. Assoc. Petr. Geol.. vol. 31. no. 9. PP. 1619-1663. ‘ Quarles. Miller. Jr. . 1953 Salt-Ridge Hypothesis on Origin of Texas Gulf Coast Type Faulting. Bull. Am. Assoc. Petr. Geol.. vol. 3?. no. 3. pp. 489—508. Reedy. Frarlk. Jr. l9'+9 Stratigraphy of Frio Formation Orange and Jefferson Counties. Texas. Bull. Am. Assoc. Petr. Geol.. vol. 33. no. 11. pp. 1830- 1858. 109‘ Sheets. Martin M. Diastrophism During Historic Time in the Gulf Coastal Plain. Bull. Am. Assoc. Petr. Geol.. vol. 14, no. 7. pp. 903-916. Steinmayero Re A. 1930 Phases of Sedimentation in Gulf Coastal Prairies of Louisiana. Bull. Am. Assoc. Petr. Geol.. vol. 14. no. 7. pp. 903-916. Stomp L. "0 1945 Resume of Facts and Opinions on Sedimentation in Gulf Coast Region of Texas and Louisiana. Bull. Am. Assoc. Petr. Geol.. V01. 29. n0. 9’ pp. IBM-13350 Todd. John D. l9l+l (and Roper. Frank C.) Sparta-Wilcox Trend of Texas and Louisiana. Bull. Am. Assoc. Petr. Geol.. vol. 24. no. 4., pp. 701-715. Varvaro, Casper G. 1957 Geology of Evangeline and St. Landry Parishes. La.. La. Dept. of Cons.. Geol. Bull. 31. 295 pp. Wallace. W. B.. Jr. 1994 Structure of South Louisiana Deep Seated Domes. Bull. Am. Assoc. Petr. Geol.. vol. 28. no. 9. pp. 1299-1312. Waters. J. A. 1955 (with McFarland. P. W. and Lea. J. W.) Geologic Framework of Gulf Coastal Plain of Texas. Bull. Am. Assoc. Petr. Geol.. vol. 39. no. 9. pp. 1821-1850. WeekS. Le Go 1950 Factors of Sedimentary Basin Development That Control Oil Occur- rence. Bull. Am. Assoc. Petr. Geol.. vol. 36. no. 11. pp. 2071- 2121+. ahissellanaaualflefezsncas Oil and Gas Field Development in United States and Canada. Yearbooks 1938-1958 (Review 1937-1957). on and Gas Map of Louisiana. 1956. La. Dept. of Com.-Geol. Survey. 110 Opelousas Quadrangle. Louisiana, 1956 Edition, U. 3. Arm Corp of Engin- eers. Vicksburg, Miss. Interpretation Hand-Book for Resistivity Logs. Schlumberger Document Number 1i. Schlumberger Well Surveying CorporatiOn. July. 1950. APPENDIX l‘llld. {I'll we we. .34 .8 .9: - .oom .hoo am}... 35A seaweed-mane e be 3er meme mm on .82 a .z BSA as we we assesses e . .03 .3 .mm - . Ohm .W 0.3.... . .WHMH do RENE «one .e .2 as .u Rm own m as we as d courageous. 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TENNESSEE A. F? I( A. hl 55 IA 8 Q < T 0. V; \ 2 ‘5 m < 4 . m < .J p. \‘>$ q 9: OO‘ \ \z 0 TH? DA 2;1%: FLOR‘ % BATON.ROUGE LAKE CHARLES ‘ . LAFA'YETTE Q/\:\ \ NEW‘ORLEAN C2; <5 WASHINGTON FIELD STATE MAP SCALE OF MILES 50 IOO __f‘ *T Tfi SOURCE MAP OF THE UNITED STATES BY THE NATIONAL GEOGRAPHIC SOCIETY I955 PLATE 2 EVANGELINE / ACADIA AVOYELLES WASHINGTON FIELD ‘ ST- LANDRY OPELOUSASS <> 0 1 A T“ WASHINGTON FIELD O L OIL PARISH MAP SCALE OF MILES I0 I SOURC E 20 3 AND GAS MAP OF LOUISIANA I956 WEST BATON ROUGE \§\\\ F:IOTUOGNE /2‘f I I P 3/7 v -__- ' ' TM“ m” ”WWW—”W“ m w mm". W. PL ATE 4 A I8 I7 I6 5 {21.333 [I LINE OF CROSS SECTIONS 53.1 __-...__.._-I . ._- - _ - — .—_. g; ___._ WELLS OF CROSS SECTION 0_ ENCIRCLED a SCALE—FEET Q 2090 40‘00 L J 3 I9 33 20 2I V DRAWN AND COMPILED BY GORDON UTTER SEPT 9, I958 T 4 S 29 380’ FQIOOOJ. 28 V 99 ?7 ~ " "‘ ”I " 2b 25) 250’ F@eOSI 39¢ a. 33 34 “ 35 36 \I75’\FQS795 (50’ F@9Ia4)? 40*\\ I30’ F@8287 30'” @7584 L ‘ w . g, a I I : I I I I25’ F@944279 I 4 4. 3 I? I 2 I I. I I . I I I I I I I I . 9 IO I II I I2 ‘ T , I I 5 I I I 4;: , I ‘ I z . I _._--_..._-_L.I_._ _______ -_ _ I - _ ‘ I i I I y I e I I '6 I5 I4 I I3 I I I / . I I : . \\\~\\I / ' ' I. WASHINGTON ': SSSCZ/ I W, 27 I L - _//_, _ / L - I a R4E R5E , f R4E RSE' ISPI PLATE 6 ‘ .- - -.:-_. 54 I8 I7 l6 >- L 8974\\ I 55 STRUCTURE “: I . . WASHINGTON FIELD E LL; ST LANDRY PARISH, LOUISIANA I; CONTOURED ON 2 HETEROSTEGINA CORRELATION POINT CONTOUR INTERVAL 50 FEET (DATUM; MEAN SEA LEVEL) O SOAEEC'FEET 4000 -59——— --—-—_~ I9 1. 20 2I L I ' j / ,/I 5500 / \ \ DRAWN AND COJIIIJILIIEYD‘ISEBGORDON UTTER (I) .IS -I .- ' , .I \. . I 300 I (:9, 8897 , r , J ‘ / .\ I 55P'I\\ g7.) I"? (95" {I15}... \ L I I \ I I I / I i f V .. - _ . __ Z‘f—T550058OI’FEI—55/ I” A 28 1‘. 5507 I 9 CO V I” ”I? * * 26 25 I I.“ i 8 I - I I -—..-.‘..._____ -..__ _. ._- v.” . _._- _ r—I \ U [NR 25: 35 \ 36 /\.70: ,/ EN- (SO‘F @9ID4)? /\U 80'-F @7684 / _ .- 9| I30 FC‘ZBZBI —‘—— 25 FL"? 9479 (DUI—I .1. ,. g. as.»— .u - at -n- «a ‘_-LLF -.~ w-‘nw o-.. “A G (D N) N ___.__. -~—{7r 29 éflomfl. I\ 6886 PLATE 7 STRUCTURE OF WASHINGTON F! D ST LA RY PARISH, LOUIS ANA CONTOURED ON TOP OF MIOCENE A SAND CONTOUR INTERVAL 50 FEET (DATUM MEAN SEA LEVEL) SCALE-FEET O 2000 4000 E I —I DRAWN AND COMPILED BY GORDON UTTER JULY 9,1958 I I \ 1'. \ I, Ar \ , \ l-’ 1/ . i I I I I..__.__.V. . . . . I . I I I I I I I I I I l N I J- G I ()1 250' F @ 809I 3 287 (DUI-4 /> <0 6_ . _ -h, ._-_..—. .__. ‘flw /’ >3» LL32” 8 / ' Q ‘ / 5 , L, (SO’F @2 SIM)? 803E @7664 I / m U ~ // / /// fl/ / I/ '/ /' / / /// / / /; / ,/ 1’ /\\ ‘\ WASHINGTON 27 , . v m—ve"W' *FWV‘w-mu A v >... R4E . _ ' RSE 20 j 40 . ' \ 56 . ' , , ’ PLATE 8 J\‘ 55 54 I8 ‘ . I7 I6 * WWW WW . " / \ . ' I , ' . STRUCFTURE . - 42 / ' WASHINGTON FIELD '7 MI - 7 WW W“ " . -_ *W"”W"‘ ST LANDRY PARISH LOUISIANA - CONTOURED ON I6 .‘ TOP OF MIOCENE 6-4 SAND W I/ CONTOUR INTERVAL 50 FEET I . . . (DATUM; MEAN SEA LEVEL) I)?" // 58 - 59 I9 39 20 2I I SCA'EEOBFEET LG \Hw/ b / / ~( I I4 // f L 1 4 . T I? /I( , DRAWN AND COMPILED BY GORDON UTTER T " 4 V } JULY II, I958 4 S WW7“ W "W -_ 240’ FEE 74.63 8 I2 33.6 _ . . . 250' f5 _L__.____.__ . Mr W“, I W . -~ , “N \IIU\E 240' X57 - , I __I__* ”Him“ """’“"" O F 8957 a i“ O ‘ 30 DL" VYmeo. ‘ 769.6 . . 41600 G . 7595 76I6 2 ~ 7624\ I 7 > £9 7 :70 F@ 8I8( 585; I C \ I. O . I;—/ 380 Fé’IOOO. $764 ' , n 7629 7624 \ 3. c8 27 26 25 K. U «I \490’ 0 34 ‘ 35 36 00 Oo - \ "3'0”? 9795 \ 5, (Sol-F @SISAI U I" I3 F 8287 O A 90 F @7584 IR . T“ w ,. ' W 7886 (DUI—I WASHINGTON 27 RSE R4E . I 7.... ‘ ' PLATE 9 STRUCTURE WASHINGTON FIELD ST- LANDRY PARISH, LOUISIANA CONTOURED ON TOP OF MIOCENE H SAND CONTOUR INTERVAL 50 FEET (DATUM: MEAN SEA LEVEL) SCALE- FEET 59 I 9 3O. 20 2] CI) 20100 1300 DRAWN AND COMPILED BY GORDON UTTER JULY IO, I958 (Db-I 240’ FC‘Z 74 I (Db—I 27 ID a) 26 25 \o\ \ 3 ' ‘ 0 5 795 ’9 (50' Fh\ U M9287 ' A 85! eo’IF @7684, N ‘ E 4‘ w 7\ 447C} . U ‘ D 36 & I/ m; . ‘KI\ ’—__‘_—— I K5 com —I (DUI—I // _ A, > / / Es §WASHINGTON j J? < 2.- 27 R4E ’ R5E R 4 E R 5 E \ 56 ' ' PLATE I0 I ‘ /\ 55 54 . '8 I7 l6 ' . ///7 \\ I STRQfiTURE / \\ I V ‘ / I . WASHINGTON FIELD \V _. ”mm--- _.- _."_ ._,q_______4 - ' 81" LANDRY PARISH, LOUISIANA ' K a CONTOURED ON TOP OF MIOCENE J SAND CONTOUR INTERVAL 50 FEET I\_ (DATUM: MEAN SEA LEVEL) \ SCALE-FEET 03') / 58 59 I9 30 20 2} (It 2%00 4ojoo / <7 T [/A , . DRAWN AND C3133LE£$9Y5860RDON UTTER l g ’/// 240’ FC‘? 7463 S /// 300’2‘@\8957 7 , I? I 1% 2‘37,..779 7%>\ . :8, 7782 4. \ 25 36 \ 35’ __ U (50:F@9l84)? 5\ ‘ aoIF @7694 “Q I _I Rica D\ | I I I 4. I ,. T I2 T 5 5 S 8 l3 \ m WASHINGTON < ' 27 f R 4 E 240’ Fe 7.1:: 3. 54 59 —... _. .—————_._—____. WASHINGTON FIELD ST- LANDRY PARISH, LOUISIANA CONTOUR INTERVAL 50 FEET ’ (DATUM: MEAN SEA LEVEL) ___.—--—v_—-o.—» -—-- fl” .. _.___4 -- ~-.-.. __ _ SCALE-FEET o 2 000 4000 L I j‘ DRAWN AND COMPILED BY GORDON UTTER __L280med \ \_/ 580’ F@ I000. 250’ F L22 809i F’LATE II STRUCCEFTURE CONTOURED ON I’- VICKSBURG LIME JJLYIZ,I958 if} b --4 (59' F @9I84)? I 80'3F492 7684 440 8 \ W6 7¢ I I I I 55 240’ H33 74 63 54 59 am? *,,m --.—-4 fi~ 8k 580 F@ I000. IE9 3? 60% £30 8758 RSE 20 2I 98 ‘--o E. 250’ F @, SOSI 39% 9| PLATE I2 STRUCTURE WASHINGTON FIELD S‘F LANDRY PARISH, LOUISIANA CONTOURED ON TOP OF MOODYS BRANCH MARL CONTOUR INTERVAL 50 FEET (:DATUM MEAN SEA LEVEL) 4000 SCALE-FEET 2000 J l A l I J DRAWN AND COMPILED BY GORDON UTTER JULY IZ‘ I958 LOIS—I 26 ' 25 36 (50' F @9I84)? I 3 (Q 684 I 8M45'I - I 91:56 I \ .?U|\ IU ————————I+— - L-___-_ _, (DUI—I IRSE ‘ ._ .__"aad-L' ’ R 4 E R 5 E 20 j 40 l .56 PLATE l3 I9 / I AIM” j\, 55 54 I8 I7 I6 r ~ I777 7‘“ 7‘7 I8 \ / STRUOCFTURE - m .4 .. 4 42 / \ I7 , ‘ _ ____ _ -, WW , W 4__ _ _ WASHINGTON FIELD —-— ~~I / ‘1'" 7 7 7 “‘7 7““ “ “777 ‘I ST- LANDRY PARISH, LOUISIANA I6 / CONTOURED ON 3 ,/ L _ _ W i- E, / TOP OF COCKFIELD B SAND I5 / CONTOUR INTERVAL 50 FEET ‘ ’b /, IDATUM: MEAN SEA LEVEL) “MW” " ' " — “T“ ”T 0‘ , - .. [4 // 58 59 I9 ‘2: 20 . 2I QL SCAIEEiOOFEET :OjOO I3 ,// DRAWN AND COMPILED BY GORDON UTTER ' T / JULY 8, I956 4 U I2 E R-“ ,I/,// 240’ PO: 746:3 S 77 ”77,7“ ”7 “7" A 57 L -- w L- L. WI - - ~— — __ —— L -. I . . ,, 500I i‘gA8957 U I O // J‘AF'O' 3 I o’ N ---L215’.._.____E_:LT.L_FL€E- 918:-” K 21: 380’ FQ IOOOZ.9 fi 9 C ' 9I49 ‘9)“ 60 286,)“. _.____ - L... w.-- 1 "A ,- w 2? 90‘s 29 28 27 9 6 25 _.___,_-.- ‘90, 250’ F@809I 39¢ 89I6 A II, N 34 35 36 ’ I (50' F @9I84)? 80'3F @7664 I «Q ’ 75 9574 O U I 5\ I I/ I I . / I I I iI . T I I2 T 5 I 5 S , S I I3 WASHINGTON . 27 I R4E R5E R 4 E R 5 E ' 56 PLATE I4 /\ ‘ 55 54 I8 I? I6 / \\ . . STRugTURE \‘i ‘ A _ WASHINGTON FIELD ' f — W77 T7777 " ST' LANDRY PARISH, LOUISIANA CONTOURED 0N . TOP OF COCKFIELD D SAND A CONTOUR INTERVAL 50 FEET . (DATUM: MEAN SEA LEVEL) / - _ . _ / 58 A 59 I9 ; 2o 22 - (L “ALEQOOFEET / r ~ .l I J T / DRAWN ANI GSESLEID Sgsgsomw UTTER 1; 4" /-"/I/ 240’ FEB 7463 I C.“ b I ./'// ‘<>It3 s.) .,/ \ I'i. ' 300’ 5C; 895/ I I A 320 ' 29 580’ @1000. 60 ”Y A, II 99‘ ‘77 26 25 250' F@809I 59¢ 8046 35 I 36 I \ (50:-'F@9I84)? . 801E @7684 \‘WQ , 95 I I fly \Ii 50\ \ I D I 2 \ U I I 0 \ I I T I I I I2 T 5 I 5 S I 3 I I I I4 ; I3 I I I I R5E R4E R5E (.D-b—i r ,/ 225' / If 4 I373! .. I4 H D \ hm ' H '3 ’o " / .0 $0 5 § 270' Ffi9/I8CT—i I '0 "" , J 1) 4 \ 3"» . \ _ ( l 74‘ 57 //\/ 55 54 59 I7 I6 §\ 28 PLATE l5 WASHINGTON FIELD ST- LANDRY PARISH, LOUISIANA ISOPACH MAP OF THE INTERVAL TOP OF HETEROSTEGINA CORRELATION POINT TOP OF MIOO’ENE A SAND CONTOUR INTERVAL IO FEET SCAlggo-o-FEET i O l 4000 :1 0343-4 DRAWN AND COMPILED BY GORDON UTTER JULY I9, |958 27 26 25 ‘ 250’ F @ 809| 39 l370 33 I75' FQ 9 35 36 , \ \ )5, \ (50' F @9I84I? 8 ’3F @7634 I44 (DUI-I WASHINGTON 27 r . / I450 l2 (DUI—I l3 R4E R5E R5E 54 - I8 ESE) IE) 50 I / O/ / I / __ I - 42 / \I I "7 / K. : -— I‘ z a _ “I / ~\:_W* m ~ _.. I I ’/’/ '\ I I65 I ///' I ..., ,_._ ..__.._.~ 71/ _ I I55 x/ '1 .- ~- ~ ~~— D22 / 58 L;\.\ '4 // T :70 If ,2 / 4 I I, \J / ‘ g "I!“ _,___~ _ __ .,. . . .--, / I: I/// {2 // 240’ PCB? 746: IE \ ’“ " “' “ ‘ \ 57 L __ « II ,/ \ I / S . I ‘ _ ‘ D 270I F@ snag A \7‘ --— “m..- -——-28~O+———r —~ 29 380' F6? IOOO. 28 J). 23C) 9—---—-——--+ <9» OI _2_WJMML_2222 H3 EH ” " _‘~"””" ’I 2E3 ,_ ,_.__.-‘ -_. , < <~ .~_ _.-_-._ _. _..__...... _ ~._< 250’ F L33 RO9I 39¢ I265 + FAULT PLATE l6 WASHINGTON FIELD ST° LANDRY PARISH, LOUISIANA ISOPACH MAP OF THE INTERVAL TOP OF MIOCENE A TOP OF VICKSBURG LIME CONTOUR INTERVAL IO FEET SCALE-FEET 0 2090 4300 L 1 1 DRAWN AND COMPILED BY GORDON UTTER JULY I9, I958 L...__.__.___....___ ,___._ -————I I I I‘Q \I 1355 1363 \(59 F @9I94)? 80': Pg? 7684 44 (Db-I I562“? ULT 3 70 U 90! x (DUI—I FQESIE R4E ' R5E PLATE I7 55 54 '8 I? I6 WASHINGTON FIELD I ST° LANDRY PARISH, LOUISIANA I ISOPACH MAP \‘77""""_'" "T“ T W— ” ‘ __,-_ “W _ __9--__L__--_.----,,. I ___.,__.~ “-5 ” _____- OF THE IN TERVAL TOP OF VICISDSBURG LIME TOP OF MOODYS BRANCH MARL CONTOUR INTERVAL IO FEET / 58 59 I9 20 2I O SCALZEP‘OFEET ‘I L If g 1 J /K DRAWN AND COMPILED BY GORDON UTTER // JULY I5, I958 {Db-I 0 1K2? }' 2:70:F@ 9I80 W._ ‘ _ 544 9 Jsso ¢ IO 61) P0 \J 250’ F @ 809I 4 7 o, 3% 34 35' 58 I75I F69 9 4 //3£$* (DUI -I R5E .. .... “Va—m”... ... -- 'égw-;i aru‘ .53.? --¢- __ ‘r’ =‘ ~ ... u-v' w,—ul--*r -.. 4/ ’/ .‘/ . l / \ l,/ / I I 300 I}; 895/ 57 55 / \ \'. \ \ z / \\ I \I {I \I 2" 0:5 // 58 // [/Ar ,//// /lv/ _5_-.._..-_, ...qL _. _-. . 240’ FOE 74 ' ,, .__ .. ...L-_,__,_- __ _ ---, , . ._,L ___I ___LL_V,-O,I_ , -..-.. _ ,5- I'D 54 ”--.”-.I 59 \ \ \\\\ x1 PLATE I’8 WASHINGTON FIELD ST LANDRY PARISH, LOUISIANA ISOPACH MAP OF THE INTERVAL 20' 2! TOP OF VIC1I§SBURG LIME THE TOP OF COCKFIELD D SAND CONTOUR INTERVAL IO FEET SCA LE-FE E T 2000 4000 i i j DRAWN AND COMPILED BY GORDON UTTER (DUI—I _ "”5... _5_____. _ __ “W"“Ir— _- I4 5 I3 h... -J, “.-....“ R5E JULY I5, I958 4 —- -~ A .98 27 .5 " 26 2‘3 250’ F@809I ‘ 39¢ 34 35 36 (50'~F @9I84)g7 IBO’ F 8287 ¥ SO'IF @7684 I 08/: T {46625 I r I (g) 887" \I 50’ . //o/ I 0 \ 2 I U I I D O 0 I II I I2 T I 5 I ‘72 I D.) I ,<...__._,_.,__ 7,. _ . ”..., -R4E RSE‘ PLATE I9 I I I 55 . 54 I Ia / I-_i-_,_ 4'Iiijg...;; . / . - 1 ~~- ~< / 7 I _ WASHINGTON FIELD IR \\d, , I; " ST- LANDRY PARISH, LOUISIANA »“ I ISORACH MAP - ,-7 .- 7 > _V > _ __ >_ 7 _ A - , ,, I ._ .._-, ,3 -» ,7..--_ 3 _‘w- -_ . -___ I ___ ,__ __ __ ___, < .___.________~___ -m. A I, _‘___--_-, _ ,,,_ __ -3 .- OF MIOCENE H SAND CONTOUR INTERVAL 20 FEET SCALE-FEET O 2090 4OOO .L 1 J g m -___v____-_....__.4 A__«.___-__._ .__._II I “'0 I k // 58 , I 59 I9 % 2O DRAWN AND COMPILED BY OOROON UTTER JULY I9, l958 m 4:. —-I (£34 ___U.__..~__.,-,__--.-.__.__._._v._ _. _ -___ “.-..--” 7.___ _-._.-__I M l/1 Few? OIBO W i I \ I » ~ —— 250’ '@ 809I 39 20' '20 ,' . 32 3 33 9.3 35 ' 36 \ 1 O \ \/ \‘Q 175I F69 9795 \ \ (50' F @9I84)? I U % 30’ Fqsza? MN I 4 I A O. - __ ___—___. I- 40' I I 42 '1 I I I 3 .: 2 / I I 3 50' n; I f 63‘ I 5 E (II—I (DUI-I ,"/ I’ ‘ I/ \\ I, 1,; 6 O ., ,// ' \ 2‘) II / 5% " \ I7 XXI/'1, I I ‘7 / \ ;/ z I , ,’ . / I I\ w) \:\ / {>‘ * \ 5. . /’\ ,r”/ ,. 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