Selected References of Alastair M. Reid

1986, Belize, Central America: geologic models for certain Paleozoic reservoirs in the Permian Basin; West Texas Geological Society Bulletin, v. 25, no. 6, p. 4–11.

1987, Basinal Lower Permian facies, Permian Basin: Part I - Stratigraphy of the Wolfcampian-Leonardian boundary; West Texas Geological Society Bulletin, v. 26, no. 7, p. 5–9.

1987, Basinal Lower Permian facies, Permian Basin: Part II - Depositional setting and reservoir facies of the Wolfcampian-Lower Leonardian basinal carbonates; West Texas Geological Society Bulletin, v. 26, no. 8, p. 5–10.

1987, Dolomitization of Holocene Mg-calcite supratidal deposits, Ambergris Cay, Belize; Geological Society of America Bulletin, v. 98, p. 224–231.

1987, Strawn biostratigraphy and lithofacies: what is the Caddo?; Transactions with Abstracts, Southwest Section AAPG, Dallas, TX, p. 100–105.

1988, Stratigraphic architecture of Pennsylvanian and Lower Permian facies, northern Midland Basin, Texas, in B.K. Cunningham, ed., Permian and Pennsylvanian Stratigraphy, Midland Basin, West Texas: Studies to Aid Hydrocarbon Exploration; Permian Basin Section SEPM Publication No. 88-28, p. 1–6.

1988, The Pennsylvanian-Permian boundary in shelf areas of the North Platform of the Midland Basin; West Texas Geological Society Bulletin, v. 27, p. 5–8.

1988, Paint Rock and Paint Rock Southwest fields, Concho County, Texas: Strawn analogue of modern shelf island systems; West Texas Geological Society Bulletin, v. 27, p. 5–10.

1988, Sedimentary textures of Recent Belizean peritidal dolomite; Journal of Sedimentary Petrology, v. 58, p. 479–488.

1989, Lower Permian platform and basin depositional systems, Northern Midland Basin, Texas, in P.D. Crevello, J.L. Wilson, J.F. Sarg, and J.F. Read, eds., Controls on Carbonate Platform and Basin Development; SEPM Special Publication No. 44, p. 305–320.

1989, Depositional-sequence analysis of Lower Permian progradational systems, Midland Basin, Texas, in E. Franseen and W.L. Watney, eds., Sedimentary Modeling: Computer Simulation of Depositional Sequences; Subsurface Geology Series No. 12, Kansas Geological Survey, p. 47–50.

1989, Revised fusulinid biostratigraphic zonation of Wolfcampian and Lower Leonardian strata in the Permian Basin, in D. Lindsay, R. Ross, and B. Swartz, eds., Transactions Southwest Section AAPG, p. 83–87.

1989, Geologic evolution of the San Simon Channel area, northern Midland Basin, Texas, in D. Lindsay, R. Ross, and B. Swartz, eds., Transactions Southwest Section AAPG, p. 55–66.

1989, Geologic setting, stratigraphy, facies, and depositional- diagenetic history of Ropes West and Y.O.C. (Pennsylvanian) fields, Hockley County, Texas, in D. Lindsay, R. Ross, and B. Swartz, eds., Transactions Southwest Section AAPG, p. 147–155.

1990, B.C. Canyon field: a low sea level stand, early Canyon carbonate buildup, in J.E. Flis and R.C. Price, eds., Permian Basin Oil and Gas Fields: Innovative Ideas in Exploration and Development; West Texas Geological Society Symposium, p. 119–129.

1990, Lowstand carbonate reservoirs: Upper Pennsylvanian sea level changes and reservoir development adjoining the Horseshoe Atoll (abstract); AAPG Bulletin, v. 74, p. 221.

1991, Depositional and diagenetic history of an upper Pennsylvanian (Virgilian to Missourian) fore-shelf platform, Ropes West and YOC.fields, Hockley County, Texas, in Transactions SWS-AAPG, p. 93–100.

1991, The Cogdell field study, Kent and Scurry Counties, Texas: a post-mortem, in M. Candelaria, ed., Permian Basin Plays, Tomorrow’s Technology Today; West Texas Geological Society, Publication 91-89, p. 39–66.

1991, Late Strawn and Early Canyon highstand and lowstand shelf edges and reefs on the Eastern Shelf with examples from Schleicher and Tom Green Counties, Texas, in M. Candelaria, ed., Permian Basin Plays, Tomorrow’s Technology Today; West Texas Geological Society, Publication 91-89, p. 118–119.

1991, The effects of Late Paleozoic paleolatitude and paleogeography on carbonate sedimentation in the Midland Basin, Texas, in M. Candelaria, ed., Permian Basin Plays, Tomorrow’s Technology Today; West Texas Geological Society, Publication 91-89, p. 139–162.

1991, The Permian Basin, in H.J. Gluskoter, D.D. Rice, and R.B. Taylor, eds., The Geology of North America, v. P-2, Economic Geology, U.S.; Geological Society of America, p. 339–356.

1992, B.C. Canyon field, Howard County, Texas: an ancient analogy to modern tropical tower karst terrains (abstract), in D.W. Cromwell, M.T. Moussa, and L.J. Mazzullo, eds., Transaction SWS-AAPG; West Texas Geological Society, Publication 92-90, p. 291.

1992, Perriwinkle-Perriwinkle North fields, Martin County, Texas: a Cisco-Canyon lowstand reef complex, in D.W. Cromwell, M.T. Moussa, and L.J. Mazzullo, eds., Transaction SWS-AAPG, Publication 92-90, p. 61–78.

1992, Shelf edges, reefs, and associated stratigraphic traps on the Eastern Shelf, in D.H. Mruk and B.C. Curran, eds., Permian Basin Exploration and Production Strategies: Applications of Sequence Stratigraphic and Reservoir Characterization Concepts; West Texas Geological Society, Publication 92-91, p. 61–63.

1995, Practical applications of sea level fluctuations, paleontology, paleogeography and environment of deposition applied to the search for small (but numerous) stratigraphic traps, in P.H. Pause and M.P. Candelaria, eds., Carbonate Facies and Sequence Stratigraphy: Practical Applications of Carbonate Models; PBS-SEPM Publication 95-36/Permian Basin Graduate Center Publication 5-95, p. 81–82.

1999, Glacio-eustatic sea level fluctuations and the formation of Pennsylvanian age carbonate reservoirs in the Permian Basin of west Texas, in D.T. Grace and G.D. Hinterlong, eds., The Permian Basin: Providing Energy for America; West Texas Geological Society, Publication 99-106, p. 71–79.

Extended Abstract

The “Abo” or Leonardian 1 composite sequence (L1 CS) is the earliest in a series of prolific Permian shelf and shelf margin complexes of Leonardian-Guadalupian age and marks the transition from the more paleogeographically complex late Pennsylvanian-Wolfcampian isolated buildups to the more organized shelf margin platforms of the remainder of the Permian. Spectacular outcrop data from the west side of the Permian Basin (Apache Canyon) provides a clear picture of the L1 stratigraphic framework with the most prominent features being a forced regressive highstand followed by prominent paleokarst. Core, log, and 3D seismic data from the Kingdom Field fits this model and illustrates the importance of outcrop-based stratigraphic models for interpretation of seismic data.

The 100-230 ft thick L1 represents the basal or lowstand sequence set of the 6 Leonardian composite supersequences making up the Leonardian supersequence (Fitchen, 1996). The L1 composite sequence consists of three aggradationally stacked high-frequency sequences making up the transgressive sequence set and three highstand sequences of bundled sigmoid to oblique-toplapping clinothems. Highest-quality reservoir facies development is in the platform-margin grainstones and grain-dominated packstones of the TSS. The Abo “reef” facies commonly referred to in the subsurface is volumetrically insignificant (<5% of total Abo).

Paleokarst development at the top-L1 sequence boundary culminates this low-accommodation depositional cycle. Within the 4 sq mi area of Apache Canyon, 63 sinkholes and collapsed caves define a distinct shelf-margin-parallel trend situated between 1 and 2 mi landward of the shelf margin. The karst-modified sequence boundary can be traced both landward and basinward to a featureless paraconformity. Maximum cave size is 120 ft in height and 400 ft in diameter, with most caves defining a circular profile. A minimum of 120 ft of relative sea-level fall is required to produce this paleokarst profile.

The Kingdom Abo Field is situated at the L1 basin margin in Terry and Hockley counties and produces from upper slope fusulinid packstones and grainstones and shelf-crest peloidal grainstones of the highstand sequence set. The L1 at Kingdom Field is roughly 3 times thicker (600-700 ft versus 120-230 ft) than the outcrop, and consistent with this higher accommodation, highstand clinothems are more sigmoid and preserve up to 100 ft of shelf-crest peloidal grainstone. Paleokarst development is evidenced at Kingdom by collapse breccias that extend up to 400 ft below the unconformity surface and cavity systems that are infilled by overlying lower Clear Fork sediments. Production data define a narrow shelf-parallel sweet-spot for the Abo. Using the outcrop-based stratigraphic and paleokarst models, this trend is interpreted to be a combination of maximum grainstone thickness and paleokarst overprint.

Extended Abstract

Grayburg Formation is one of the most prolific hydrocarbon producing intervals in the Permian Basin. The Grayburg was deposited upon a carbonate ramp as a series of shallowing-upward cycles, cycle sets, high frequency sequences, upper and lower larger sequences to form a composite sequence of mixed carbonates and siliciclastics. Carbonates are dominant and siliciclastics are subordinate. All carbonates and carbonate matrix within siliciclastics have been dolomitized.

Grain-rich carbonates (grainstone, mud-poor packstone and mud-rich packstone) were deposited upon a carbonate ramp in a high-energy, ramp crest to initial middle ramp, shoal to shallow marine setting within wave base to near wave base. Mud-rich carbonates (wackestone and mudstone) were deposited in a low-energy, inner ramp and outer ramp, back-shoal and “deeper” shallow marine settings behind and beneath wave base. Rapid, very strong transgressions (TST) positioned grain-rich carbonates furthest up the ramp. These deposits form the basal cycle in cycle sets. Highstand progradation (HST) positioned grain-rich carbonates down the ramp. Storm events modified and enlarged this profile and spread grain-rich carbonates further updip (storm flooding) and downdip (post-storm surges). Storms ripped up and incorporated mud-rich intraclasts into grain-rich carbonates.

Prevailing winds created windward margins on the east side of the Central Basin Platform and in the Apache Mountains. Leeward margins were established on the west side of the Central Basin Platform and Eastern Shelf. The Northwest Shelf and Guadalupe Mountains were in an oblique windward position. In the Guadalupe Mountains facies tracts typical of both windward and leeward deposition have been recognized and documented.

Grain-rich carbonates were cross bedded within wave base and by storm events. These deposits are commonly bioturbated, which partially to completely eliminated cross bedding. In high-energy wave base ooids and coated grains formed, with admixtures of skeletal detritus and intraclasts. Most of these grains were converted to peloids by micritization of individual grains and by dolomitization. Occasionally, grain coatings are visible in thin section and in reflected light.

Eolian siliciclastics (subarkose to calclithite) were transported across subaerial exposed portions of the carbonate ramp during above average to major drops of sea level. Subsequent transgressions onto the ramp reworked siliciclastics into offshore shallow marine, and occasionally lower shoreface, settings as slightly bioturbated, calcareous sandstones. Unlithified carbonate sediment was reworked and mixed with the siliciclastics. Transgressions and storm events during transgression (post-storm surges) transported siliciclastics in a basinward direction. Large storm events incorporated highly saline water from updip ponded evaporites to form bottom hugging density currents/turbidites. These events transported siliciclastics into the basin. Siliciclastics stranded on the ramp form the base of shallowing-upward carbonate cycles. They are dolomitic sandstones and were diluted downdip to form sandy dolostones. Source of the siliciclastics was from northern New Mexico (present-day Sangre De Cristo Mountains) and the Wichita Mountains in southern Oklahoma..

Cycle tops up ramp were subaerially exposed, with the most common exposure surface indicator being plant rootlet (rhizolith) molds and casts. Teepee structures, fenestral porosity, algal laminations, mud cracks, reworked intraclasts, collapse breccia, pisolites, oncolites, reworked terrestrial red beds, and evaporite crystal molds and casts have all been documented on or near subaerial exposure surfaces.

Cycle tops down ramp are conformable surfaces. Recognition of individual cycles is somewhat difficult. Individual cycles tend to form thicker composite cycles, where some small cycle tops appear as bed boundaries within larger cycles.

Bedding within cycles is thinner up ramp and thicker down ramp. Updip cycles are approximately 3 ft. (1 m) thick, whereas cycles downdip are approximately 10-12 ft. (3-4 m) thick.

Reservoir quality carbonate porosity was created or preserved by: 1) depositional controls, such as, grain-richness, bed thickness, grain size, and grain type; 2) subaerial exposure and dissolution; 3) dolomitization and dissolution (burial diagenesis); and 4) dissolution during regional uplift (late diagenesis). Best reservoir rocks are grainstones and mud-poor packstones that are thick to massive bedded and well sorted. Mud-rich packstones are thinner bedded, less well-sorted, and form poor quality reservoir. Mud-rich carbonates, wackestones and mud-stones, are even thinner bedded, mud-dominanted, and form the lateral updip reservoir seal (stratigraphic trap).

Porosity within oil saturated dolomitic sandstones was created by feldspar dissolution (secondary porosity). Permeability of these siliciclastics is low due to the high percentage of dolomite matrix and some trace amounts of authigenic kaolinite in the pore system. On average, 16% porosity is required to generate 1 md. of permeability. Down ramp the siliciclastics form baffles (aquatards) to vertical and lateral fluid migration. However, pressure can cross siliciclastic beds. Up ramp the siliciclastics contain less porosity and permeability, are poorly oil saturated to unsaturated, and form barriers (aquacludes) to vertical and lateral fluid migration.

In some portions of the Northwest Shelf and Central Basin Platform washing during transgression removed carbonate fines from siliciclastics, which preserved good interparticle porosity. In these areas siliciclastics are good reservoir rocks.

Siliciclastics serve as excellent marker beds and can be correlated in outcrop and in the subsurface. Correlations of siliciclastics have been made from the Central Basin Platform through the Northwest Shelf, Grayburg type section (Grayburg-Jackson field), to outcrops in the Guadalupe Mountains (Irabarne Canyon).

Flow unit geometries are variable. Ramp crest to initial middle ramp, grain-rich cycles, which do not contain mud-rich bases, were deposited as a stacked series of carbonate cycles that act as a single, large flow unit. Up ramp, strong transgressions deposited grain-rich carbonate cycles updip in an inner ramp setting and interstratified them with mud-rich carbonate cycles. In this position, individual grain-rich carbonate cycles act as small flow units. Some flow units may have been modified by fracturing events and by dissolution events. Water cycling is a common problem during secondary recovery waterfloods in both thick and thin flow units.

Dissolution events, whether during subaerial exposure, burial diagenesis, or diagenesis associated with regional uplift, focused most fluid flow horizontally through grain-rich cycles. Effects of these dissolution events enlarged original interparticle porosity and created moldic, microvugular and vugular secondary porosity and solution-widened pore throat radii connecting the pore system. Total porosity was increased. However, permeity and lateral horizontal connectivity were drastically improved. Injected water and gas, during secondary and tertiary recovery, follow these original dissolution pathways.

West of the Permian Basin, Late Cretaceous-Early Tertiary compressional tectonism emplaced thrust sheets along the present-day Rio Grande River. This tectonic event reactivated older Precambrian and Pennsylvanian fault systems further to the east in the Permian Basin. Recurrent movement of pre-existing faults folded the overlying Permian section to create combination structural-stratigraphic traps along shelf margins throughout the basin.

In the middle Tertiary extensional tectonics, that created the Rio Grande Rift, dramatically effected Permian Basin reservoirs. The first phase of tectonism was initial uplift and slow extension of the rift in the Late Oligocene-Early Miocene (Chapin and Cather, 1994). The east limb of the rift extended from the center of the rift, at the present-day Rio Grande River, to the west edge of the Central Basin Platform in the Permian Basin. Uplift recharged an enormous amount of meteoric water into the subsurface of the Permian Basin (Lindsay, 1998). Oil columns within fields were partially to completely swept to produce residual oil intervals, at residual oil saturation to waterflood (Rorw). The second phase of tectonism was rapid extension, in the Middle-Late Miocene (Chapin and Cather, 1994), with the development of grabens, such as, the Hueco Bolson and Salt Flat grabens. This tectonic phase destroyed the large recharge area and left only small mountain ranges, such as, the Apache, Davis, Delaware, Glass, Guadalupe, and Sacramento mountains attached directly to the Permian Basin. These mountain ranges continue to recharge meteoric water into the Permian Basin, but at highly reduced rates.

Following breakup of the large recharge area displaced oil could re-migrate and re-saturate reservoirs that had been swept. Resulting fluid distribution in some reservoirs appear odd, with potential gas caps high in the reservoir, with an oil band lower in the section, and a residual oil interval at the base of the reservoir. In some cases the closure was re-saturated with gas to produce a gas field, even though the entire closure is oil stained. In other cases the closure was never re-saturated with mobile oil or gas and has remained at residual oil saturation. Dead oil/heavy oil intervals can be scattered throughout the reservoir and elemental sulfur may be present in the lower more highly water washed and bacterially modified part of the reservoir. Many residual oil intervals are referred to incorrectly as transition zones. The third phase of tectonism was quiescence in the Pliocene to Recent (Chapin and Cather, 1994), with erosion down cutting into mountain ranges and stream piracy.

Extended Abstract

This paper describes the stratigraphy, sedimentology, petrology, and reservoir petrophysics of the Grayburg and Queen Formations in Means Field, Andrews County, Texas. Its objectives are to characterize and map their depositional lithofacies; interpret the depositional and diagenetic origins of their reservoirs; and develop a regional geologic model that will improve understanding and development of these reservoirs. The Grayburg and Queen Formations were deposited in coastal and shallow shelf environments during a series of sea level fluctuations. Four shelf facies were defined from core and thin-section descriptions: a distal shallow shelf to open shelf lithofacies, which consists of bioturbated and massive peloidal and fusulinid dolowackestones and rare dolopackstones; a shallow shelf lithofacies, which contains bioturbated, massive, and laminated skeletal and peloidal dolowackestones and dolograinstones; a shoal lithofacies, which consists of cross-laminated ooid sandstones and ooid dolopackstones and dolograinstones; and a back-shoal lithofacies, which consists of peloidal dolowackestones and dolograinstones. Five coastal lithofacies were also defined: a shoreface lithofacies, which consists of burrowed, dolomite and anhydrite-cemented siltstones and very fine-grained sandstones and quartzose dolostones; a carbonate tidal flat lithofacies, which is composed of desiccated, algal-laminated and fenestrated dolomudstones and coated grains; a siliciclastic tidal flat lithofacies, which contains planar cross- laminated and deformed wavy-laminated siltstones and very fine-grained sandstones with burrows, ripple-laminations, algal laminations and displacive anhydrite nodules; a river-mouth bar lithofacies, which consists of massive very fine- to fine-grained sandstones and siltstones with scour surfaces, planar horizontal to ripple cross-laminate, and syndepositional deformation structures, and ripple laminated mudstones and siltstones; and a coastal sabkha lithofacies, which consists of bedded, nodular mosaic anhydrite and fine-grained reddish-brown sandstones and siltstones with displacive anhydrite nodules and beds.

Vertical repetition of lithofacies was used to identify small-scale (1-10 m) shallowing upward cycles and determine the relative position of lithofacies along the profile. These shallowing-upward cycles are related to high-frequency low-amplitude sea level fluctuations that affected platform sedimentation. In the Grayburg Formation, carbonate sedimentation dominated the platform during sea level rises, whereas sea level falls are marked by cycles dominated by nearshore depositional systems and an upward increase in siliciclastic content. In the Queen Formation, prograding siliciclastic nearshore and fluvial cycles are overlain by transgressive carbonate cycles. This depositional cyclicity often creates highly layered, heterogeneous reservoirs.

Means field produces from subtidal (shallow shelf and shoal) Grayburg dolostones and Queen river-mouth bar sandstones and siliciclastic tidal flat sandstones. Reservoirs appear to be both depositionally and diagenetically controlled, as lateral and vertical variations in porosity and permeability reflect variations in depositional texture, dolomite texture, and anhydrite cementation.

Extended Abstract

The Matador Arch is part of a major, fault-bounded, positive structural trend that runs for approximately 350 miles. The trend stretches from Wichita County, Texas to Chaves County, New Mexico. Specifically, the Matador Arch separates the Midland Basin to the south from the Palo Duro Basin to the north. The major movement on this fault system was initiated in the Late Mississippian and continued through the Early Pennsylvanian.

In the spring of 1994 Wagner and Brown Ltd. and Burlington Resources conducted a 53 square mile 3D seismic survey in portions of Hockley and Lamb Counties. This survey crossed the Matador Arch. After review of the survey, a study was initiated using the few deep well logs available within a six-county area around the 3D survey. This led to a better understanding of both the structural style and how this structural event effected deposition of sedimentary strat in the area around and on the arch.

Interpretation of the 3D survey has led to the conclusion that the Matador Fault System is a strike-slip system. Movement on the faults created a series of highs during the Late Mississippian. This movement was in response to the collision of the North American plate with the South American /African Plate. Movement continued during the Early Pennsylvanian which can be associated with deposition of a thick section of Early Pennsylvanian clastic deposited both south and north of the fault trend. Pennsylvanian shelf-edge carbonates of Mid and Late Pennsylvanian Strawn, Canyon and Cisco age were deposited south of the Matador Arch and extended over and across the arch into the Palo Duro Basin. No large-scale effect in deposition of these shelf carbonate units can be directly attributed to movement of the arch at the time of deposition. It can be argued that paleotopography, set up by this earlier movement, led to the development of these carbonate shelf trends. A younger series of shelf-edge carbonates continued to build across the arch through the Early Permian Leonardian. No large-scale effects are observed in these deposits either.

The 3D Seismic allows us to produce isochron maps for intervals within the Pennsylvanian and Permian strata. We interpret some depositional thickening in the Permian from the Tubb Formation through the Rustle Formation. Observed minor trends of thickening and thinning across paleo-shelf edges may be due to minor fault movement, compaction, or a combination of processes. We have concluded that the Matador Fault System had no appreciable movement during the post-Leonardian part of the Permian. Complex stratigraphy in the pre-Tubb Permian section makes structural interpretation difficult. We have concluded that these pre-Tubb shelf margins show no major changes in strike direction. We also conclude that the fault system had no major influence on deposition of these pre-Tubb shelf strata.

A final episode of fault movement, most likely during the Laramide orogenic phase, rejuvenated the Matador Fault System. This movement is responsible for reshaping the structural aspects of the area and led to the present-day structural configuration.

Extended Abstract

University Block 9 Field in Andrews County, Texas, was originally developed on 80-acre spacing in the early 1950’s. Previous field studies indicated that it was a trap-door structural closure from pre-Cambrian basement through Permian lower Wolfcamp sediments. The Devonian Thirtyone Formation was interpreted to be a reef that grew on the structural high. Utilizing formation micro-imaging logs, conventional cores, and 3D seismic, a new interpretation of the field’s reservoir architecture has evolved. Field production has increased by more than 2000 BOPD by applying this revised interpretation to a program of infill drilling and short-radius horizontal re-entry wells.

Nearly two dozen wells were logged with electrical imaging logs in an effort to better characterize the reservoir properties. Over 8000 feet of image logs were combined with more than 1000 feet of interpreted core data and rescaled gamma ray curves to define the architecture of this limestone reservoir. The best porosity was preserved in shelf packstones and wackestones where interparticle mud inhibited the precipitation of rim cements. Rescaled gamma ray curves were used to differentiate the packstone- wackestone intervals from higher energy lithofacies in the absence of core data. The distribution of the porous, low energy facies was identified by isopach mapping of high gamma ray intervals.

Electrical image logs were combined with 3D seismic data in order to characterize the size and distribution of reservoir compartments. Seismic interpretations suggest that the structural history for University Block 9 Field is one of transpressional tectonism. A high angle fault, arcuate in shape, and varying in throw, defines the southern and western boundaries of the field. Numerous subordinate faults, antithetic to the field-bounding fault, further segment and compartmentalize the reservoir.

Portions of the field with porous packstone and wackestone lithofacies, juxtaposed to non-porous rudstone lithofacies by faulting, were selectively developed using inexpensive, short radius, lateral re-entries. Eight horizontal re-entries, ranging from 1000 to 1700 feet long, have been drilled with the goal of reaching into untapped reservoir compartments.

Two successful laterals were intentionally drilled through small sealing faults into undrained reservoir compartments. Another horizontal well was drilled to within 300 feet of a fault-separated well making less than 20 barrels of oil per day. This horizontal well had initial production exceeding 200 barrels of oil per day, and is still producing more than 50 barrels per day. Additionally, two of the laterals were drilled out of old, virtually depleted wells and were successfully completed in new reservoir compartments at rates exceeding 150 barrels of oil per day.

By incorporating these new technologies into planned infill wells, an old, poorly understood field has been rejuvenated. Infill and horizontal drilling have increased the field’s production rate by more than 2000 barrels of oil per day. This is the highest production level in 25 years, and it has been accomplished with half the number of active wellbores.