Wilcox Formation Research Articles

Mixed-Layer Clays in Eocene Interlaminated Shales and Sandstones: ABSTRACT

Kaolinite, illite, and mixed-layer montmorillonite-illite are present in interlaminated sandstones and shales from the Eocene Wilcox Formation of the Texas Gulf Coast at depths of 2,000 to 4,000 m. Ratios of kaolinite to discrete illite are higher in the sandstones than in the interlaminated shales. Mixed-layer clays in the sandstones are 5 to 20% more expansible and less ordered than those in interlaminated shales. These mineralogic differences are interpreted to reflect a significant difference in the solution chemistry of pore waters in the sandstones from that of pore waters in the interlaminated shales. At the relatively shallow depth of 2,000 m, mixed-layer montmorillonite-illite from the shales is roughly 30% expansible; this figure is significantly less than the 7 % expansibility reported by J. Hower et al for Miocene age mixed-layer clays at similar depths. Assuming similar source and geothermal gradient for the two sets of samples, two explanations may account for these differences. The most plausible explanation is that the expansibility of the mixed-layer clay is controlled by the montmorillonite-to-illite transformation rate. Because the Eocene sediments have had an additional 25 m.y. to react, the montmorillonite-to-illite transformation is more complete in these samples. An alternative explanation is that the chemistry of pore waters in the Wilcox Formation is significantly different from that of pore waters in sediments studied by Hower. End_of_Article - Last_Page 469------------

Mineralogic Composition and Diagenesis of Tertiary Sandstones along Texas Gulf Coast: ABSTRACT

The upper Gulf Coast Wilcox Formation is composed dominantly of quartz with feldspar, metamorphic and volcanic rock fragments, and mud clasts. The lower Gulf Coast Wilcox Formation contains more quartz and volcanic rock fragments. Lower Gulf Coast Yegua and Jackson Formations are composed of quartz, volcanic, and lesser carbonate rock fragments. Northward they become more quartz-rich and contain metamorphic rock fragments and mud clasts. Lower Gulf Coast Frio and Vicksburg Formations are similar to the Yegua and Jackson. Northward, they become more quartz-rich, but carbonate rock fragments are absent. Despite variations in composition, Tertiary sandstones exhibit a similar diagenetic sequence idealized as follows. Surface to shallow subsurface diagenesis (0 to 4,000 ft; 1,200 m) begins with pedogenic clay coats and with leaching and calcite replacement of feldspar. Minor kaolinite, feldspar overgrowths, and iron-rich carbonate material are also precipitated. Porosity is commonly reduced by compaction from the original 40% to less than 30%. Moderate subsurface diagenesis (4,000 to 11,000 ft; 1,200 to 3,300 m) involves leaching of early carbonate cements and subsequent cementation by quartz overgrowths and later carbonate cement. These stages commonly reduce porosity to 10% or less, but this trend may be reversed by late leaching of feldspar, rock fragments, and carbonate cements. Restoration of porosity to more than 30% can occur, but this may be reduced by late cementation by kaolinite and iron-rich dolomite and ankerite. Deep subsurface diagenesis (11,000 ft; 3,300 m) is a continuation of late iron-rich carbonate cements. End_of_Article - Last_Page 440------------

Depositional Environments Interpreted from Stratigraphic, Seismic, and Paleoenvironmental Analyses, Upper Wilcox, Katy Field, Texas: ABSTRACT

ABSTRACT Upper Wilcox deposits (Late Paleocene to Early Eocene) at Katy Field in southeastern Texas, consist of terrigenous clastic facies which are stratigraphic equivalents to the uppermost beds of the outcropping Wilcox Formation. Wilcox sediments extend basinward to a known total subsurface thickness of 9100 feet at Katy Field. The Upper Wilcox is 1800 feet thick at Katy; however, only the upper 800 feet were included in the study. Analysis of the regional stratigraphy, structural trends and paleobathymetric relationships indicate that sediments were deposited by high-constructive and destructional delta systems marginal to the subsiding Gulf of Mexico basin; resultant deltaic and interdeltaic facies were ultimately transgressed by open shelf environments. The interpreted depositional sequence begins with prodelta silty clay at the base and coarsens upward to very fine- and fine-grained sands in a typical progradational delta-front sequence. Progradation was repeated after abandonment and subsidence, yielding a second series of delta-front and overlying fluvial facies. The next vertical sequence consists of thinly laminated and burrowed silty clay and thin sand beds, which are locally slumped and micro-faulted, and sand units containing shale clasts. These thin units represent a period of minor sediment influx and comprise interdeltaic marsh to offshore silty clay and destructional delta-front sand facies environments; local distributary channels cut into the bay-marsh transition facies. The third vertical sequence is largely offshore silty clay, thin glauconite beds, and thin silty sand units, which onlapped the area as a result of increased subsidence and marine transgression. Local relict shoreline sand units were deposited during temporary stillstands as the shoreline shifted landward.

A Comparative Study of the Diagenetic Alteration of Clay Minerals in Mesozoic Shales from Papua, New Guinea, and in Tertiary Shales from Louisiana, U.S.A.

AbstractGradual change from 60% montmorillonite/40% illite randomly interstratified clay minerals at 3500 ft depth to 20% montmorillonite/80% illite at 10,200 ft can be observed in a complete section of Mesozoic shales at Barikewa in New Guinia. The top of a similar complete type Mesozoic section at 10,544 ft in the nearby Omati borehole contains 20–40% montmorillonite in randomly interstratified montmorillonite/illite. From 10,800 ft downward there is only 10–20% expandable material. Consequently depth of burial rather than stratigraphic level controls the proportion of expandable material present. Similar diagenetic alterations occur in the Wilcox Formation, Louisiana, also controlled by burial.The amount of illite 2M polymorphs in the Papuan samples is usually less than 5 per cent, the illite 10Å peak sharpness ratio is about 1·4. Corresponding values for the Louisiana samples are 43% 2M polymorphs and about 2∙0 sharpness ratio. Chemical analysis of the Papuan shales show low MgO and K2O values when compared with the Louisiana samples. The latter sediments contain some chlorite, the former hardly any. Differences demonstrate a higher proportion of relatively unweathered material in the American samples.Increase of chlorite content, increase of magnesium content and decrease of kaolinite content from 12,368 ft down in the Louisiana samples suggests a change in sedimentation pattern.

Let's Improve our Wilcox Success Rate!: ABSTRACT

For the last three years exploratory success in the Eocene Wilcox Formation of southwestern Mississippi has averaged 6.7%, far below the success of 1951-1953 when an 11% success rate was achieved with less than a third of the wildcat wells now available for control. If we are to reverse this trend, the geologists must improve sampling and testing procedures in the field and more effectively utilize well data in the office and laboratory. Serious errors in elevations and well locations, deviated hole problems, inadequate sampling of wildcat wells, and incomplete evaluation of oil shows have contributed to an excessive number of dry holes. The present success rate can be improved by greater use of isopach maps to supplement structural contouring, by a better understanding of the relation of oil to regional subsidence and remigration, and by more careful evaluation of core analyses to differentiate between live oil and residual oil. End_of_Article - Last_Page 2034------------

Northeast Thompsonville Field, South Texas: Key to Future Exploration for Downdip Wilcox Production?

The general configuration of the Northeast Thompsonville field structure, Jim Hogg and Webb Counties, south Texas, was well defined by detail seismic surveys conducted in the area prior to the drilling of the first well. Early drilling proved that the major down-to-the-east fault controlling accumulation on the anticline dips 27°. This invalidated certain assumptions that were made regarding the strike of the fault during the early development of the field. As the field was developed, the true alignment and dip of the fault were established, and it was found that the producing Hinnant Sand (Wilcox Formation) in structurally low wells has much lower permeability than in the structurally high wells. These and other data indicate to the writer that the Hinnant Sand was n offshore bar. The possibility exists that the low-angle fault is related directly to the slip face (seaward side) of this bar; this might explain the absence of hydrocarbon accumulations on the downthrown sides of certain Wilcox faults along this trend. Another interesting aspect of the study is the evolution of ideas on the structure of the area. Figure 1 is the structural interpretation before the prospect was drilled; Figure 2 is the interpretation after the field discovery; and Figure 3 is the latest interpretation.

Developments in Arkansas and North Louisiana in 1963

This report covers that part of the Gulf Coastal Province located in North Louisiana and Arkansas, and the Paleozoic area of northwestern Arkansas. The District includes 26 parishes of North Louisiana and all of Arkansas. There was an over-all increase in drilling activity in 1963 as compared with the previous years. North Louisiana had a record-breaking year in the number of wells drilled. This was due to an increase in development drilling in the Wilcox trend and Saratoga-Annona Chalk areas of Sabine and Caddo Parishes. There was also an increase in exploratory drilling. Arkansas showed an increase in development and a decrease in exploration drilling activity. Fourteen new fields were discovered in North Louisiana and 5 new fields were discovered in Arkansas. Sandstones of the Wilcox formation accounted for the largest number of new-field discoveries in North Louisiana. Four of the new-field discoveries in South Arkansas were in the Nacatoch, Meakin, and Baker sands and the Smackover limestone. In North Arkansas the discovery was in the Atoka (Pennsylvanian) sand. The most important exploration activity in Arkansas was in search of gas in the Arkoma basin in the northwestern part of the state. Exploratory drilling was active in the Wilcox areas in the eastern part of North Louisiana, and in the western part the Saratoga and Annona Chalk areas were most active. Exploration activity will probably remain about the same during 1964 as was present in 1963. Arkansas' most important activity will be centered in the Arkoma basin while activity in North Louisiana will again be centered in the Wilcox, Sligo, Hosston-Cotton Valley, and Saratoga-Annona Chalk areas.

Yegua and Wilcox Potential, Upper Texas Gulf Coast: ABSTRACT

In the past, the Yegua and Wilcox Formations, of Eocene age, have been major exploration objectives in the Upper Texas Gulf Coast. The Yegua has been a prolific producer and has received widespread investigation along established trends. It has been only within relatively recent times that attention has been given to the downdip potential, especially as concerns the basal sands in that formation. The Wilcox has not received the same intense exploration in regard to complete penetration of the entire section. In detail the Wilcox is very difficult to correlate, and markers must be established to guide exploration. Marine wedges, or zones with source-bed connections, exist, and a tentative middle marker has been proposed to identify one such zone. The configuration of the Wilcox and Yegua depositional basin is considered to be important for downdip exploration. Major regional tectonic features had an effect on deposition as did faults and structural movement contemporaneous with deposition. Dip and east-west sections indicate regional sedimentation changes. The utilization of regional studies along with detailed local investigation helps to explain existing production. The same tools can be used as a guide for future exploration. End_of_Article - Last_Page 1965------------

Developments in Arkansas and North Louisiana in 1960

This report covers a part of the Gulf Coastal Province located in North Louisiana and Arkansas, and the Paleozoic area of northwestern Arkansas. The district includes 26 parishes of North Louisiana and all of Arkansas. There was a decrease in drilling activity in 1960 as compared with the previous year. In North Louisiana, the decrease in the number of wells drilled was due to the lack of development drilling. Exploration activity increased slightly over 1959. Arkansas showed a marked decrease in both development and exploration drilling activity. Twenty-one new fields were discovered in North Louisiana and 5 new fields were discovered in Arkansas. As in the past, sandstones of the Wilcox formation accounted for the largest number of new-field discoveries in North Louisiana. Four of the new-field discoveries in Arkansas were in sandstones of the Atoka formation of Pennsylvanian age. The most important exploration activity in Arkansas was in search of gas in the Arkoma basin in the northwestern part of the state. Exploratory drilling was dominant in the Wilcox and Tuscaloosa areas in the eastern part of North Louisiana and in the western part searching for Paluxy pools. Interest was again shown in the Hosston and Cotton Valley of Jackson, Lincoln, and Ouachita parishes. Exploration activity will probably remain about the same during 1961 as was present in 1960. Arkansas' activity will be centered in the Arkoma basin while activity in North Louisiana will again be centered in the Wilcox, Tuscaloosa, Hosston, and Cotton Valley sandstone-trend areas.

Bar-Finger Sands of Mississippi Delta: ABSTRACT

Elongate, lenticular sand bodies, termed bar fingers, characterize the Mississippi birdfoot delta sedimentary complex. They underlie the 15-20-mile-long principal distributaries or passes of the river which radiate from Head of Passes, and have formed in response to long continued distributary-mouth-bar deposition. These sand bodies attain a thickness of more than 250 feet and a width of as much as 5 miles. Their thickness results in part from subsidence brought about by compaction of underlying clays, and the width beneath a given pass is comparable to that of the actively forming distributary-mouth bar. The sand bodies comprise beds of well sorted, fine to very fine sand or silt and occasional thin layers of clay and silty clay. Diagnostic features are numerous cross-be ded thin layers in which the principal elements dip gulfward, laminae composed of root and wood fragments, sand-size grains of lignite, and an absence of faunas. The bar-finger sands grade downward into delta-front silty clays which rest upon deeper marine prodelta clay deposits. Laterally they interfinger with extensive thick clay sections which accumulated in delta-front, bay, and marsh environments. The sands are transitional with overlying natural-levee, marsh, and bay deposits. Locally, the bar fingers have been disturbed by the upward movement of clays from underlying deposits to form mud lumps. Bar fingers are distinguished from other sand bodies in the Recent deposits of the Mississippi deltaic plain by their greater thickness and their pattern of distribution. Their ancient counterparts have been recognized in the Pennsylvanian Booch sands of Oklahoma. Abnormally thick sand masses present locally within the Eocene Wilcox and Sparta formations of Louisiana may also be deltaic bar-finger sands. End_of_Article - Last_Page 1249------------

Postdiagenetic Clay Mineral Environmental Relationships in the Gulf Coast Eocene

AbstractAn extensive survey of clay mineral relationships in the subsurface Wilcox formation (Eocene) has shown progressive diagenetic conversions with depth. Montmorillonite, a common constituent of Wilcox outcrop material, becomes loss evident below 3000 ft and is not normally found in an unmixed state below the 9000—10,000 ft overburden level. At depths between 3000 and 14,000 ft, montmorillonite lattices are commonly interpersed with illite components, the frequency of which increases with depth to a virtual elimination of montmorillonite swelling characteristics below 14,000 ft.Chlorite is present at all stratigraphic levels including surface exposures. It appears to be a more dominant constituent at depth; however, observed increases in basal intensities in samples that had been more deeply buried may result from more perfect crystal development rather than quantitative differences.The diagenetic conversion of montmorillonite to illite and possibly to chlorite has resulted in a distribution of the last two minerals that is related to estimated depositional environments as reconstructed from micro-paleontological criteria in at least one well in southern Louisiana. It is inferred, therefore, that different chemical characteristics in the ancient Wilcox seas are responsible for the distribution coincidence even though the mineral groups defining the distribution were not necessarily indigenous to the ancient Wilcox sea.Correlations between clay minerals and environment are not particularly noted in the investigation of analogous environmental situations in Recent sediments, and it is thus concluded that the environment indicators which appear as minerals in lithified sediments such as the Wilcox are present in freshly deposited sediments in the form of submineralic chemical constituents such as absorbed ions, molecular groups or subcrystalline lattice configurations which are not detected by the ordinary clay mineral identification procedures. The change to mineralic form is aided by the natural “bombing” resulting from normal increases in temperature and pressure due to burial. The process is apparently a continuum through the entire subsurface residence of the sediment and the results are seemingly in accordance with phase equilibria.

Petrophysical Analysis of Some Wilcox Wells

Abstract Relationships are shown between some of the fundamental rock properties of the heterogeneous Eocene Wilcox formation along the central and eastern portion of the Texas Gulf Coast trend. Mention is made that quantitative evaluation, using the electrical logs and established correlations, often are difficult due to:variations in the shale content and cementation of the sand,variations in water salinities,thin bed effects, andinvasion effects. However, it is pointed out that this does not preclude the use of electrical logs but rather that extra care must be exercised in their interpretation. Several representative wells along a portion of the trend are reviewed ]to illustrate some of the general characteristics of the formation and the individual utility of some of the logging devices. Particular emphasis is placed on the value of drill cuttings and sidewall cores, as well as capillary pressure data which indicate pore size distribution and which, in turn, are related to porosity, permeability and water saturation. It was concluded that conventional coring usually is not essential for evaluation of exploratory wells along this portion of the Wilcox trend inasmuch as proper logs, in conjunction with cuttings and a few sidewall cores, generally provide adequate data for evaluation. A recommended evaluation program for down-dip Wilcox exploratory wells penetrating either the upper or both the upper and lower section is presented. It is stressed that the suggested program is necessarily general and therefore flexible and should be considered only as a guidein selecting evaluation procedures. Introduction Evaluation of the Eocene Wilcox along the Texas Gulf Coast trend varies from relatively simple cases, as exemplified by a typical well in the upper Wilcox at Mercy, Tex., to the more difficult ones such as found in the lower Wilcox at Sheridan, Tex. In either instance, quantitative evaluation of potential pay sections requires information concerning the porosity, permeability, and formational content (oil, gas or water), or more fundamentally, as Archie has shown, such evaluation should reveal the distribution of each phase (oil, gas or water) within the pores of the rock, The evaluation should not be limited only to permeable rocks containing hydrocarbons, but should include also the impermeable layers as well as the permeable layers containing water.

Application of the Material Balance Equation to a Partial Water-Drive Reservoir

Abstract The present paper contains a method which combines the material balance equation with the water influx equation to obtain reliable values for the active oil originally in place and a quantitative evaluation of the cumulative water influx. The method is illustrated by an application to a reservoir without original gas cap. In the absence of an original gas cap, results may be obtained using only field production and pressure data, PVT analyses, and a minimum of subsurface information. Characteristics of Reservoir and Reservoir Fluids Production in the field under review is obtained from the top of the Wilcox formation of Eocene age, at a depth of approximately 8,100'Ft subsea. The structural map, Fig. 1, shows that the accumulation, half elliptical in shape with the long axis in east-west direction, is trapped to the north and on the upthrown side of a normal fault. A number of east-west faults with additional minor faulting in random directions are found in the general area, and seismic information and production performance indicate in this particular case the existence of a second fault a short distance downdip, with a strike more or less parallel to the fault controlling the accumulation. It is estimated that 1,830 acres were originally underlain by oil and that the maximum thickness of the original oil column, about 37 ft, was only slightly greater than the maximum thickness of the oil-bearing sand. Maximum net sand thickness was estimated at approximately 26 ft. From logging and subsurface information the gross sand volume has been placed at 37,400 acre-ft, which reduces to about 27,500 acre-ft after probable non-productive intervals have been deducted. The following table presents laboratory analyses data for the Wilcox sand cores.

Report on the Mamou Field Pressure Maintenance Project

Abstract The Mamou Field, located in Evangeline Parish, La., is an elongatedanticlinal structure on the downthrown side of a major east-west fault with oiland gas production from the upper part of the Wilcox formation. Two mainproducing horizons occur at an approximate depth of 11,500'Ft and have beendesignated the Morein sand and the Deshotels sand. The upper sand (Morein) had an original bottom-hole pressure of 6,788 psig, which is some 1,500 psi above the normal pressure for that depth. Oilproduction with high gas/oil ratios and fluid analyses giving high shrinkagefactors prompted a study of the reservoir in its early stages. The resultsindicated a closed reservoir producing under solution gas drive with lowexpected ultimate oil recovery. The early study of the Wilcox formation and its contained hydrocarbonsresulted in the presentation of the data to the Department of Conservation ofthe State of Louisiana, with suggestions for field rules and a request forpermission to inject extraneous water into the Morein sand. The water injectionplans eventually led to complete unitization of working and royalty interests, to the construction of a gasoline plant, and to a central tank batteryinstallation for the field. Deshotels sand wells were reworked to the Moreinsand, and the water injection system was installed and ready for continuousoperation in the early part of 1949. The injection of water was started in timeto arrest the bottom-hole pressure decline at or near the bubble-pointpressure. This injection was calculated to increase the ultimate recovery andto conserve natural resources. Pressure maintenance, the extraction of LPGproducts, and the sale of residue gas (early 1950) represent an attempt toproduce an oil field with utmost efficiency. Introduction The two principal Wilcox oil horizons in the Mamou Field are the Morein sandand the Deshotels sand, occurring at 11,500'Ft and 11,700'Ft subsea, respectively. Minor oil production has been encountered in Morein stringersands. (Fig. 1.) This paper deals only with the Morein sand, which is blanket over the MamouField. It is, however, segmented by the northwest-southeast "E" faultas shown in Fig. 2. The west segment is the area involved in the waterinjection pressure maintenance program. To date the east segment has operatedlargely under the influence of a strong water drive. The paper presentsbrief history of field development,resume ofreservoir conditions which led to the decision to inject extraneous salt waterinto the principal producing horizon, andsummary of reservoir analysisand performance. T.P. 3192

Fearn Springs Member of Wilcox Formation in Mississippi: GEOLOGICAL NOTES

Fearn Springs Member of Wilcox Formation in Mississippi: GEOLOGICAL NOTES

Surface and Subsurface Correlation of Wilcox Formation in West-Central Louisiana: ABSTRACT

Surface samples of the Wilcox and Midway formations were collected and examined for lithologic characteristics and faunal content. These formations exhibit a cyclic pattern of deposition. Fossils are rare. The surface equivalents were examined in the subsurface and it was noted that the cyclic pattern exhibited in the outcropping formations extended with marked regularity into the subsurface. Microfossils and macrofossils were examined from cuttings and a number of these were used along with the cyclic pattern, to correlate the surface formations with their equivalents in the subsurface. End_of_Article - Last_Page 2069------------

Ground Water and Geologic Structure of Natchitoches Area, Louisiana

The municipal water supply of the city of Natchitoches has been obtained for many years from shallow wells screened in fine-grained sands of the Wilcox formation. These sands have been over-developed and the supply of water stored in the sands has been depleted gradually as the recharge from rainfall has failed year by year to equal the withdrawals by wells. An exploratory program designed to locate an adequate supply of ground water was initiated in the fall of 1943 by the City of Natchitoches. This program, directed by the Geological Survey, United States Department of the Interior, included the drilling, electric logging, and testing of nine exploratory wells which penetrated water sands of the Sparta sand and of the Wilcox formation. Geological and hydrological data obtained from the test drilling suggest that the city of Natchitoches may be situated on a downthrown fault block defined on the southwest by a fault along Youngs Bayou and on the southeast by a fault extending from Old River toward Cane River Lake. Salt water, unlike connate sea water in composition, is present in the sands underlying most of the city. A similarity of topographic, geologic, and hydrologic conditions in this area to those in salt-dome areas in near-by parishes is evident. Southwest of the city, abundant supplies of soft water were found in the Sparta sand and in the sands of the Wilcox formation. These sands crop out in a narrow band extending from Natchitoches into Texas, and generally yield moderately large quantities of potable water in the areas immediately south of their outcrops. A supply of at least 1,000,000 gallons a day for the city of Natchitoches may be obtained from three to five properly developed supply wells in Secs. 10, 56, and 57, T. 8 N., R. 7 W. Additional water for increased needs of the future may be provided by extending this well field toward the west.

Midway-Wilcox Surface Stratigraphy of Sabine Uplift, Lousiana and Texas

The Sabine uplift of northwestern Louisiana and northeastern Texas is reflected on the surface by a large inlier of Midway, Wilcox, and lower Claiborne sediments. Surface work in this area revealed the presence of three Midway and four Wilcox formations. The formations consist typically of a basal sandy member, a middle lignitic and carbonaceous shale member, and an upper calcareous silt and shale member. The following nomenclature is proposed for these sediments. Wilcox group Carrizo formation Sabinetown formation Pendleton formation High Bluff member Slaughter Creek member Bayou Lenann member Marthaville formation Midway group Hall Summit formation Bistineau member Grand Bayou member Loggy Bayou member Logansport formation Lime Hill member Cow Bayou member Dolet Hills member Naborton formation (base not exposed) The Midway and Wilcox beds are largely deltaic and barren of fossils, but marine faunas are present therein around the southern flank of the uplift. These faunas permit correlation with the type Midway and Wilcox sediments of Alabama and Mississippi. The mapping methods employed revealed surface indications of nearly all the known oil and gas fields of the area.

Developments in Southeastern United States in 1941: ABSTRACT

Outstanding development trends in the Southeastern United States during 1941 were the following. End_Page 911------------------------------ 1. A decided decrease in wildcat activity with only approximately one half the number of wells completed as during 1940. 2. The continuation of a curtailed geophysical program comparable to the last months of 1940 with a slight upturn toward the end of the year. 3. The inception of core drilling programs by eight major companies with more emphasis placed on this type of exploration, as well as on surface geology. 4. A continuation of the leasing program in south Mississippi and its extension into Alabama and Florida. 5. The review and revision of geological and geophysical data with an attempt to eliminate the sources of error as revealed by negative results of exploration in 1940. There were several additional events of importance in the area. Development in the Tinsley field seemingly outlined the limits of production from the shallow sands. A new sand, the McGraw, was discovered on the north edge of the field in the basal part of the Eutaw formation. Two new fields were discovered in Mississippi, the Sharpsburg field in T. 11 N., R. 3 E., Madison County, and the Cary field in T. 11 N., R. 7 W., Sharkey County. The Sharpsburg field, which may be an extension of the near-by Pickens field, was discovered by C. L. Morgan's Johnny No. 1 in Sec. 4, T. 11 N., R. 3 E. The producing sand is known as the Wilburn sand and is the first sand in the Eutaw formation. The Cary field was opened by the British-American Oil Co. Houston No. 1 and the production is from Selma gas rock of Navarro age. Neither area has had sufficient exploration to evaluate its future. Of geological importance was the limiting of the Mississippi salt basin on its northeast side by the Union Producing Co. Waite No. 1 in Clarke County, Alabama, and the Magnolia Petroleum Co. Culpepper No. 1 in Lauderdale County, Mississippi. The Union Producing well drilled to a total depth of 12,399 feet and near the bottom penetrated formations which are correlated with the Buckner, Smackover, and Eagle Mills formations of Louisiana and Arkansas. In the Eagle Mills formation, interbedded shale and salt was cored suggesting proximity to the edge of the salt deposit. The Magnolia well in Lauderdale County encountered rocks of Paleozoic age at a depth of 6,060 feet so that the limit of the salt deposit is between these two wells. Of first importance geologically is the presence of the mackover limestone indicating its presence across the Mississippi basin into Alabama. This suggests the possibility of production in porous horizons comparable to producing areas in Arkansas and Louisiana. In Alabama and Florida there was extensive geophysical and leasing activity. In the latter state many of the large tracts were taken under geophysical option or otherwise leased. The same was true of southern Alabama and to a less degree, southern Mississippi. Nothing of importance occurred in Georgia. Two new salt domes were discovered in Mississippi. Kings dome was found by the Magnolia Petroleum Co. Hall No. 1 in T. 7 N., R. 4 E., Warren County. The Halifax dome was discovered by the Plains Producing Co. in T. 7 N., R. 4 W., Hinds County. The Magnolia Petroleum Co. Hall No. 1 encountered a saturated section in the top of the Wilcox formation. A test resulted in showing the presence of low-gravity asphaltic oil and water. Although this had no commercial value, the presence of oil in the top of the Wilcox formation was indicative of its productive possibilities elsewhere. End_of_Article - Last_Page 912------------

Developments in Southern Arkansas and Northern Louisiana During 1940

Annual oil production for this area during 1940 increased by 3,546,270 barrels, or 7.6 per cent over the figure of the previous year. South Arkansas produced 25,790,380 barrels and North Louisiana 24,381,760 barrels, making a total of 50,172,140 barrels. Of the 169 wells drilled in southern Arkansas, 53 were dry; 131 of the 651 North Louisiana wells were dry. Most of the wells in southern Arkansas were drilled to the Smackover formation, with the Hosston formation a close second. In northern Louisiana a great majority of the wells ended in the Gulf series, while the majority of the remaining wells ended in the Eocene series. Prospecting and development in southern Arkansas continued to point to the Smackover formation, while in northern Louisiana the search for Wilcox production predominated. Southern Arkansas had one new gas-distillate field producing from the Smackover limestone, a new oil field producing from the Paluxy formation, and one producing from the Hosston formation. Northern Louisiana had two new oil fields and two new gas fields producing from the Wilcox formation, and one gas field in the Paluxy. A new field from the Hosston was in prospect at the end of the year.