Ranch Field Research Articles

Ground-dwelling spiders in agroecosystems of the Dry Chaco: a rapid assessment of community shifts in response to land use changes

ABSTRACT Deforestation and land-cover changes have transformed the Argentinian Dry Chaco into a mosaic dominated by crops and ranch fields. Although land-use activities are seen as one of the major driving forces of biodiversity loss, the specific impacts in this ecoregion are poorly understood. In this study, we analyse the effects of land uses and management on ground-dwelling spiders in agroecosystems of the Dry Chaco, in the North of Argentina. We identified four land-use classes: secondary forests, pastures, orchards, and crops. Additionally, 15 environmental variables were recorded within these land-use classes. Management, tree cover and species richness of trees, shrubs and herbs were the most important variables determining spider community composition. Three families, lycosids (Lycosidae), thomisids (Thomisidae), and zodariids (Zodariidae), were associated as taxonomic indicators as well as functional indicators of the different groups of land uses; thus suggesting that functional traits of ground-dwelling spiders reflect habitat changes within the agricultural landscape they inhabit.

Model calibration and optimization of a post-combustion CO2 WAG pilot in a mature oil field

A carbon dioxide (CO2) water-alternating-gas (WAG) pilot was conducted to gain insights into tertiary oil recovery potential via CO2 flood in the West Ranch Field as part of the Petra Nova project, the world's largest post-combustion CO2 capture and utilization initiative. With a fluvial formation geology, this is a challenging and novel application of CO2 enhanced oil recovery. The aim of this study is two-fold. First, to build a predictive dynamic model that incorporates the data acquired during the pilot operation. Second, to utilize this model to provide guidance for optimal design for a field-wide CO2 EOR operation.This study began with an initialization of the pilot sector model extracted from a calibrated full-field model. The pilot model calibration follows a two-step hierarchical workflow. First, we performed a large-scale update of the permeability distribution by integrating available bottomhole pressure and multiphase production data. Next, local permeability field is fine-tuned using a streamline-based method to match CO2 breakthrough times at the producers. The predictive capability of the calibrated model was verified through two blind validation tests: (1) the model showed good agreement with saturation logs acquired at two observation wells; and (2) the model reproduced the CO2 recovery as a fraction of the injected CO2.Sensitivity studies were conducted using the calibrated pilot model to evaluate the effects of various operational parameters. Finally, we performed a Design of Experiment based multi-objective optimization of the CO2 WAG processes using the influential operational parameters identified from the sensitivity analysis.

Pitfalls in the seismic interpretation of fault shadow events — Vicksburg formation of south Texas

Reliance on prestack time-migrated seismic data to define structural highs without incorporating all subsurface data and without taking into account the regional and local lateral depositional trends may result in dry holes or poorly positioned production wells due to local velocity changes, which are usually caused by some depositional or structural phenomenon. Tying check-shot control to depositional units may reveal those phenomena and permit assumptions to be made about velocities in areas beyond check-shot control points. We discovered a significant gas accumulation in an area surrounded by dry holes and marginal wells in the Vicksburg Formation in McAllen Ranch Field, Hidalgo County, Texas, by treating a seismic velocity anomaly as a geologic problem and by simple application of arithmetic and geometry to a 3D velocity model. Due to the effects of the anomaly, seismic data displayed in time gave no indication of the existence of a 325 ha (800 ac), 150 BCFG anticlinal structure. A subsurface model that accounted for the velocity anomaly was able to predict its extent and severity by readily identifiable thickness changes in the anomalous units. The resulting discovery yielded a sevenfold increase in field production within a two-year time span.

Geologic factors controlling CO2 storage capacity and permanence: case studies based on experience with heterogeneity in oil and gas reservoirs applied to CO2 storage

A variety of structural and stratigraphic factors control geological heterogeneity, inferred to influence both sequestration capacity and effectiveness, as well as seal capacity. Structural heterogeneity factors include faults, folds, and fracture intensity. Stratigraphic heterogeneity is primarily controlled by the geometry of depositional facies and sandbody continuity, which controls permeability structure. The permeability structure, in turn, has implications for CO2 injectivity and near-term migration pathways, whereas the long-term sequestration capacity can be inferred from the production history. Examples of Gulf Coast oil and gas reservoirs with differing styles of stratigraphic heterogeneity demonstrate the impact of facies variability on fluid flow and CO2 sequestration potential. Beach and barrier-island deposits in West Ranch field in southeast Texas are homogeneous and continuous. In contrast, Seeligson and Stratton fields in south Texas, examples of major heterogeneity in fluvial systems, are composed of discontinuous, channel-fill sandstones confined to narrow, sinuous belts. These heterogeneous deposits contain limited compartments for potential CO2 storage, although CO2 sequestration effectiveness may be enhanced by the high number of intraformational shale beds. These field examples demonstrate that areas for CO2 storage can be optimized by assessing sites for enhanced oil and gas recovery in mature hydrocarbon provinces.

Slick-Water and Hybrid Fracturing Treatments: Lessons Learned

This article, written by Technology Editor Dennis Denney, contains highlights of paper SPE 89876, "Slick-Water and Hybrid Fracture Treatments in the Bossier: Some Lessons Learned," by Mukul M. Sharma, SPE and Phani B. Gadde, U. of Texas at Austin; Richard Sullivan, SPE, Richard Sigal, SPE, Robin Fielder, SPE, and David Copeland, SPE, Anadarko Petroleum Corp.; and Larry Griffin, SPE, and Leen Weijers, SPE, Pinnacle Technologies, prepared for the 2004 SPE Annual Technical Conference and Exhibition, Houston, 26-29 September. To better understand the process of fracturing tight gas sands, a comprehensive data set was gathered and analyzed for the Bossier formation in the Dowdy Ranch field. The bottomhole treating pressures were higher than expected on the basis of the measured stress profiles. Effective fracture lengths derived from pressure-buildup analysis and history matching of production data were significantly shorter than designed fracture lengths (or those predicted from uncalibrated fracture models). The data collected and analyzed provided valuable insight into the performance of water and hybrid fracturing treatments in tight gas formations. Introduction Waterfracs and hybrid fracs are the stimulation treatments used in many low-permeability reservoirs. Typically, improving the performance of gas wells in marginal gas plays requires improvement of fracturing technologies. To ensure that these gas wells remain economically attractive, even at modest gas prices, completion and fracturing practices must be optimized. Research was aimed at improving the performance and reducing the cost of fracture treatments by acquiring and analyzing fracture-treatment data from the Bossier play in east Texas. Six gas wells (data wells) were identified in the Dowdy Ranch field for a detailed analysis of the well and fracture-treatment data before, during, and after a fracture treatment. The full-length paper details data acquired in Anadarko Petroleum Co.’s Anderson No. 2 well, summarizes findings, and presents recommendations for better fracture treatments on the basis of lessons learned.

Structural evolution of a detached delta system—the Vicksburg of south Texas

The Oligocene Vicksburg formation of South Texas was deposited as a coarse clastic delta system on the fringe of the uplifted Sierra Madre mountains in Mexico. Earliest Vicksburg sediments were initially deposited in a simple delta lobe, which detached due to gravity from underlying Eocene formations and crept seaward as a block, creating a depositional center. The upper Early Vicksburg contains expanded sets of deltaic sediments which infilled a depression formed by the initial movement. Downlap surfaces indicate that the expansion was oriented northeast-southwest. Middle Vicksburg uplift in the Sierra Madre mountains to the south caused erosion and a change in strike direction to northeast-southwest and a significant change in structural style. West to easterly oriented ridges formed in conjunction with significant north-south, en-echelon, counter-regional growth faults. The ridges later accumulated hydrocarbons in deformed sandstones. Counter-regional faults formed as a deeper detachment within the underlying Eocene during Late Vicksburg time. This resulted in formation of two different structural provinces. The Slick Ranch Field province illustrates a complex extensional zone dominated by horst and graben structures. In contrast, the McAllen Ranch Field province is simpler, without Late Vicksburg extension. One of the keys to successful exploitation of the Vicksburg is unraveling extensive, low angle, discontinuous fault sets that dominate the majority of rotated fault blocks. These faults formed during growth and rotation of individual slump structures. Faulting occurred when curvature on listric fault planes was reduced and the slump rotated to a horizontal position. When rotation was complete, all the curvature from the base of the slump was transposed to the upper surface. Subsequent low angle faults dissected the crest of the slumps. The study area, in Starr and Hidalgo counties, South Texas (Figure 1), borders the Rio Grande River and Mexico. More than six trillion ft3 of gas and …

Ghost Ranch Field, Nevada: New Discovery from Combined 3-D Seismic and Well Log Data

Ghost Ranch field was discovered in 1996 on the basis of a 3-D (three-dimensional) seismic survey guided by analysis of log data from nearby existing wells. The 7 mi2 (18 km2) survey had the initial goal of identifying infill opportunities in Eagle Springs field and led to the drilling of a series of new producers. Results from this activity, combined with log data from nearby Kate Spring field, enabled the mapping of an oil-bearing Paleozoic slide-block mass between the two fields. A structural high with four-way closure, roughly 40-50 ac (16-20 ha) in size, was identified and successfully drilled to open Ghost Ranch field. Ghost Ranch produces from fractured Devonian dolomites at depths of about 4350-4400 ft (1326-1342 m). The field has a strong water drive, an oil column of 100 ft (30 m), and estimated original oil in place (OOIP) of 2 million bbl. Production through January 1999 was 216.7 mbbl (11% OOIP) from three wells. Success at Ghost Ranch suggests that the updip margins of the productive slide-block mass define an excellent target for future exploration.

Abstract: Fifty Year Old Frio/Vicksburg Cage Ranch Field in Brooks County, Texas is Rejuvenated with 3D

ABSTRACT Suemaur Exploration undertook a 3-D seismic shoot in 1994 over the apparently depleted 50-year-old Frio/Vicksburg Cage Ranch Field in central Brooks County, Texas. This 3-D survey has rejuvenated the field with the 1995-96 drilling of six wells, with eight completions in both normal pressure Frio sands and abnormal pressure Vicksburg sands. Cage Ranch Field, discovered in 1947 by Shell, had produced 99 billion cubic feet (BCF) of gas and 850 thousand barrels of condensate (MBC) from 36 wells, in 64 completions. By 1994, production was less than one million cubic feet of gas per day and 16 barrels of condensate a day. The 3-D interpretation identified three major differences between our pre- and post-drill maps. The first was that there was no roll, or west dip downthrown to the Vicksburg flexure on the west at the Middle Firo. Suemaur then drilled the highest Frio wells to date in the field. Secondly, the crest of the underlying Vicksburg structure was not coincident with the overlying Frio structure, but was over a mile south enabling us to make the first commercial Loma Blanca Sand Vicksburg age completion in the field, with the 710-1 well completed for 4.6 million cubic feet of gas per day (MMCPD) and 175 barrels of condensate per day (BCPD). Thirdly, a major arcuate, down-to-the-south embayment Vicksburg age fault was identified on the southeast flank of Cage Ranch, enabling us to drill the discovery well for Hook Field.

Permian Wolfcamp"Limestone Reservoirs: Powell Ranch Field, Eastern Midland Basin: Reply"

Deep-water carbonate channel reservoirs form important oil reservoirs along the toe of the Eastern shelf of the Permian basin in west Texas. In northwestern Glasscock County, these-Wolfcamp-reservoirs are Leonardian (Early Permian) in age and define high-energy channels incised into surrounding carbonate detritus and basinal shale. Porous grain-flow material filling these channels, along with encasing detritus, was derived from the shallow shelf located six miles to the east. Reservoirs are in packstone and grainstone facies and have significant interparticle and moldic porosity. Relevant exploration began in the 1960s, but expanded slowly thereafter due to lack of success caused by complex patterns of channel occurrence. Results of a three-dimensional (3-D) seismic survey conducted in 1990 have greatly enhanced the identification and mapping of productive channels in the Powell Ranch field complex. Wells in this complex are capable of flowing 400-1200 bbl of oil per day, and have reserves ranging from 0.2 to 1.3 MBO. The new 3-D data have improved the relevant geologic model and dramatically increased rates of drilling success. Application of such data to this setting offers a potential model for other parts of the Permian basin.

Episodic Hydrocarbon Migration during Deposition of the Frio Clastic Wedge, Gulf of Mexico: Its Expression and Causes: ABSTRACT

A petrographic and geochemical studies of the Oligocene Frio Formation show that the carbon isotopic composition of calcite varies systematically with stratigraphy, due to varying hydrocarbon migration to the sea bed during Frio deposition. In the St. Charles Ranch fields, Aransas County, Texas, compositions in the Lower Frio are relatively heavy ([delta][sup 13]C = [approximately]-2[per thousand]), decreasing stratigraphically upward to -5.5[per thousand] in the Middle Frio, then increasing to -2[per thousand] in the Upper Frio. The average calcite composition is identical in sandstones and mudstones at specific stratigraphic levels. This pattern contrasts with [delta][sup 18]O, in which sandstone and mudstone calcite has different compositions and no stratigraphic control is evident. Two limestone beds have very light [delta][sup 13]C compositions ([approximately] -20[per thousand]); they are analogous to modern carbonate buildups in the Gulf of Mexico forming around methane vents. The carbon isotopic composition of calcite reflects the flux of hydrocarbons to the sea bed: low [delta][sup 13]C values indicate greater incorporation of hydrocarbon into calcite and therefore a large hydrocarbon flux, and vice versa. The data suggest that a pulse of hydrocarbon migration occurred during Frio deposition, peaking during Middle Frio deposition. Two mechanisms for this migration pulse are considered: first,more » deposition of the Frio resulted in sudden hydrocarbon maturation and generation in underlying source rocks; and second, growth faulting, associated with deposition of the Frio wedge, opened migration pathways. As sedimentation rates slowed during deposition of the Upper Frio, movement on growth faults decreased and migration pathways closed. These mechanisms are tested with numerical models.« less

Effects of Diagenesis on Enhanced-Resolution Bulk Density Logs in Tertiary Gulf Coast Sandstones: An Example from the Lower Vicksburg Formation, McAllen Ranch Field, South Texas

Diagenetic heterogeneity strongly influences porosity and permeability distribution in sandstone reservoirs of the lower Vicksburg Formation. Enhanced-resolution bulk density logs, which use a 3-cm (1.2-in.) rather than the standard 15-cm (6-in.) sampling increment, offer important new information in understanding diagenetically complex sandstones in the subsurface. Detailed petrographic mapping and sedimentologic description of core from the Oligocene lower Vicksburg Formation of McAllen Ranch field, south Texas, have identified cement variations that result in diagenetic zones ranging in thickness from 0.1 cm (0.04 in.) to 0.9 m (3 ft). The petrographic and petrophysical properties of these diagenetic zones define three diagenetic facies that can be correlated with log esponse from the enhanced-resolution bulk density log: (1) the quartz-cemented facies, averaging 13% porosity and 0.342 md permeability, and having a recorded density greater than or equal to 2.43 g/cm3 but less than 2.48 g/cm3, (2) the chlorite-cemented facies, averaging 16.7% porosity and 0.193 md permeability, and having a recorded density less than 2.43 g/cm3, and (3) the calcite- or transitional-cemented facies, averaging 9.4% porosity and 0.04 md permeability, and having a recorded density greater than or equal to 2.48 g/cm3. Intervals cemented with different minerals are identified by the enhanced-resolution bulk density log based on the ranges in density that define each diagenetic facies. This identification of diagenetic facies not only influences the accurate determination of the net sandstone thickness and porosity of reservoirs within the lower Vicksburg Formation, but also directly controls permeability calculations. For example, classification of cement intervals from lower Vicksburg gas reservoirs using enhanced-resolution bulk density logs and porosity and permeability regressions for each of the diagenetic facies results in estimated permeability thicknesses as much as 50% greater than those calculated using standard log analysis. Because standard log analysis ignores the effects of diagenetic eterogeneity, the use of the enhanced-resolution bulk density log provides significant information that leads to more accurate reservoir and field evaluations in diagenetically complex sandstones.

Permian Wolfcamp"Limestone Reservoirs: Powell Ranch Field, Eastern Midland Basin"

Deep-water carbonate channel reservoirs form important oil reservoirs along the toe of the Eastern shelf of the Permian basin in west Texas. In northwestern Glasscock County, these-Wolfcamp-reservoirs are Leonardian (Early Permian) in age and define high-energy channels incised into surrounding carbonate detritus and basinal shale. Porous grain-flow material filling these channels, along with encasing detritus, was derived from the shallow shelf located six miles to the east. Reservoirs are in packstone and grainstone facies and have significant interparticle and moldic porosity. Relevant exploration began in the 1960s, but expanded slowly thereafter due to lack of success caused by complex patterns of channel occurrence. Results of a three-dimensional (3-D) seismic survey conducted in 1990 have greatly enhanced the identification and mapping of productive channels in the Powell Ranch field complex. Wells in this complex are capable of flowing 400-1200 bbl of oil per day, and have reserves ranging from 0.2 to 1.3 MBO. The new 3-D data have improved the relevant geologic model and dramatically increased rates of drilling success. Application of such data to this setting offers a potential model for other parts of the Permian basin.

Structural and Stratigraphic Resolution of the Permian Minnelusa Formation with 3D Seismic Data at the North Rainbow Ranch Field, Powder River Basin, Wyoming: ABSTRACT

Structural and Stratigraphic Resolution of the Permian Minnelusa Formation with 3D Seismic Data at the North Rainbow Ranch Field, Powder River Basin, Wyoming: ABSTRACT

Reservoir Heterogeneity in an Estuarine Incised Valley-fill Reservoir, Sun Ranch Field, Wyoming: ABSTRACT

Abstract Incised valley-fill reservoirs containing sand derived primarily from the sea may contain significantly more barriers and baffles to flow than fluvially filled incised valleys. In choosing well locations, designing above ground handling capabilities and predicting economics of individual wells, it is important to recognize that the geometry, scale and type of barriers to flow are significantly different in these two types of valley fills. The tidal estuarine model developed primarily by Clifton for Pleistocene and modern estuarine deposits of Wilipah Bay, Washington, provides an excellent analog for deposits of Muddy (Cretaceous) sandstones at Sun Ranch field. Individual tidal valley-fill deposits may have several relatively continuous horizontal shaley beds which form baffles or barriers to vertical flow. These thin horizontal shales represent flooding events of more than the usual daily tidal duration. The beds are: (1) dominantly clay and fine sand and silts; (2) have very low porosity and permeability; (3) prevent or deter vertical flow between reservoir compartments and act as baffles to flow; (4) are the focus of diagenetic clay formation; and (5) are easily recognizable in core but not on most logs. Tidal and tidally-reworked fluvial valley fills may have significantly lower porosity and permeability and smaller port sizes than most fluvial fills. Detrital clay also occurs as drapes, clasts and grains within otherwise very sandy beds. Anomalously low log porosities may be calculated where clay occurs as clasts and clay drapes or ripples in otherwise high quality reservoir sandstones.

The Rejuvenation of the 30-Year-Old McAllen Ranch Field: An Application of Cross-Functional Team Management

Summary This case history overview describes the application of crossfunctional team management in redevelopment of a 30-year-old south Texas gas field. Multidisciplinary cooperation and synergism were emphasized, and efforts focused on a common team goal. The results have been extraordinary; all areas have shown significant improvement, including gas production, which is up by more than 250%. Introduction By the mid-1980's, McAllen Ranch field gas production had declined to a low of 24 MMcf/D owing to reservoir depletion and curtailment. The end of curtailment and subsequent development drilling activity increased the rate to 80 MMcf/D by early 1988. However, with reduced drilling and natural decline, the rate had fallen again to about 50 MMcf/D by early 1989. At this time, a cross- functional team was established to evaluate additional investment opportunity and to develop a plan to increase production from the noncontributing reserves that were behind pipe. This team looked at all aspects of the field's production and developed a consensus plan that included acquisition, processing, and interpretation of a fine-grid 3D seismic survey; development drilling focused in the northern portion of the field (B-area); procedures to obtain regulatory approval to commingle noncontributing reserves in existing wellbores; and enhanced drilling and completion techniques. This paper describes the interaction and synergism among the various specialties and functions involved in the producing operations at McAllen Ranch and how the concept of cross-functional team management has led to the rejuvenation of this 30-year-old field. It focuses on the process of cross-functional team management rather than just the results achieved.

Hydrodynamic Effects on Mission Canyon (Mississippian) Oil Accumulations, Billings Nose Area, North Dakota

Mission Canyon oil production on the south flank of the Williston basin provides an example of an area in the mature stage of exploration that shows significant hydrodynamic effects on oil accumulations related to stratigraphic traps. The effects are illustrated by the Billings Nose fields and the Elkhorn Ranch field. The reservoirs have low hydraulic gradients of about 2 m/km (10 ft/mi), tilted oil-water contacts with gradients of 5 m/km (25 ft/mi), and variable formation-water salinities that range from brackish to highly saline. Oil accumulations in some zones are displaced off structure and downdip to the northeast, parallel to porosity pinch-outs. Other zones are pure hydrodynamic traps, lacking both structural and stratigraphic closure. Future success in exploration and development in the play will depend on recognizing the hydrodynamic effects and predicting oil displacement.

Depositional Environment of the Cleveland Formation in the Ellis Ranch and Bradford, Cleveland Fields, Ochiltree and Lipscomb Counties, Texas

Investigation of the Upper Pennsylvanian Cleveland Formation in central Ochiltree and Lipscomb counties of the northeastern Texas panhandle reveals deposition in a deltaic environment. Examination of five cores reveals dominate facies including prodelta, distal delta front, and proximal delta front. These facies are generally stacked within the cores and may be overlain by sharp-based, fining-upward intervals interpreted as distributary channel facies. The distributary channel facies generally constitute better reservoir development. Examination of well logs, cross section grids, and log facies mapping in the Ellis Ranch and Bradford Cleveland fields ties the wells with the depositional environments revealed in the cores. Northwest-southeast and northeast-southwest channels are mapped into the delta with sandstone thicks oriented roughly east-west at their termination. Thick reservoir-quality sandstone is associated with the distributary channel facies or where the various deltaic facies are stacked and of sufficient porosity to be productive.

Aventura Ranch Field: A Classic Stratigraphic Trap: James Lime, Van Zandt County, Texas

ABSTRACT Aventura Ranch Field, found September 10, 1990, is the most recent significant James Lime discovery in the East Texas Basin. Current estimates indicate recoverable reserves of 20 BCF of gas and 1.5 million barrels of condensate. The field represents a classic stratigraphic trap, formed by a facies change from downdip porous and permeable grainstones, terminating updip into carbonate mudstones, wackestones and unrelated grainstones. The James Lime formation consists of poorly-sorted, low porosity lime wackestone/mudstones, and well-sorted reservoir lime grainstones. The reservoir consists of two facies: (1) skeletal grainstones, and (2) oolitic grainstones. The skeletal grainstones are interpreted as deposits adjacent to the James Lime reef core. The oolitic grainstones were deposited as high energy shoals or bars in shallow, agitated water possibly paralleling the skeletal grainstones adjacent to the reef. Both interparticle and intraparticle porosity is present in the grainstone facies. Microporosity is also evident and is responsible for suppression of most of the induction log resistivity throughout the field. Resistivity as low as 1.5 ohms is found to be hydrocarbon productive. Subsequent to the development of the Fairway Field, a large James Lime stratigraphic trap had been sought after for many years, resulting in only the minor discovery of N. Athens Field. Several dry holes had been drilled amazingly close to the current productive area. Perseverance and persistence finally paid off with the discovery of Aventura Ranch Field. Currently the field is producing six million cubic feet of gas and 425 barrels of condensate a day. End_of_Record - Last_Page 517-------

Integrated Interpretation Processing in Noonen Ranch field

The Noonen Ranch field in Adams County, Colorado, is a Cretaceous aggradational stream deposit formed by the deposition of sand in an erosional valley carved in the D-Sandstone and Huntsman shale. The erosional valley was formed during a sea level lowstand after the conformable deposition of the D-Sandstone atop the Huntsman shale. The subsequent rise in sea level caused a series of distinct sand bodies to be deposited in the erosional valley. A number of small fields have been developed along the trace of these ancient valleys. Noonen Ranch field is a typical size field for this area, with an aerial extent of approximately 1 {times} 0.5 mi and a maximum thickness of 25 ft. Manual data manipulation and display techniques were used in the original development of these fields. Recent reworking of the data in preparation for three-dimensional modeling forced a regeneration of cross sections and maps in the field area. A workstation-based integrated system was used for this new work and several problems were encountered. The rework showed that modern technology does not help in the data compilation process in a new area but greatly speeds the generation of the displays needed for interpretation and presentation. Using thesemore » new processing tools, the interpreter can become inundated with displays, which may actually hinder the interpretation process. However, with the advent of three-dimensional modeling and processing tools, the need for integrated processing and data systems will continue to grow.« less

S"Sand Reservoir, McAllen Ranch Field, Texas: A Case Study of a Typically Complex Vicksburg Sand Wedge"

S"Sand Reservoir, McAllen Ranch Field, Texas: A Case Study of a Typically Complex Vicksburg Sand Wedge"