EXPANSION OF GAS RESERVOIR DATA BASE, PERMIAN BASIN, TEXAS
The Bureau recently completed an expansion of the gas reservoir data base for the Permian Basin in Texas to include newer and smaller reservoirs. This paper was originally published by the West Texas Geological Society in the transactions for the 2000 Fall Symposium and is reproduced here with the permission of that organization:
Reservoirs in the Permian Basin that had cumulative production greater than 10 Bcf of gas through 1986 were grouped into 18 plays in the Atlas of Major Texas Gas Reservoirs (Kosters and others, 1989). Production from these major Permian Basin gas fields was 42.3 Tcf through 1986. To expand the data base to include smaller and newer fields, we identified 143 additional reservoirs having cumulative production greater than 6 Bcf through 1998. The reservoirs were assigned to plays, and the play boundaries were modified to include the additional reservoirs.
Cumulative production from these 143 reservoirs is 2.2 Tcf. Production data include both nonassociated gas and associated gas-well gas but not associated casinghead gas. No adjustments were made for gas cycling. Greatest production has been from reservoirs in the Upper Pennsylvanian and Lower Permian Slope and Basinal Sandstone play (479 Bcf) and the Strawn Group Shallow-Marine Carbonate play (383 Bcf). The plays having the greatest number of additional reservoirs are the Upper Pennsylvanian and Lower Permian Slope and Basinal Sandstone (30 reservoirs), Siluro-Devonian CarbonateDeep Delaware and Val Verde Basins (21), Strawn Group Shallow-Marine Carbonate (18), Ellenburger Fractured Dolostone (14), and Atoka Group Limestone and Sandstone (12).
Figure 1. Paleogeographic setting of the Permian Basin during the Late Permian (modified from Silver and Todd).
This paper updates the data base of major gas reservoirs in the Permian Basin (Figure 1, above) compiled by Kosters and others (1989). The original delineation of gas plays in Texas was published by Kosters and others (1989) in the Atlas of Major Texas Gas Reservoirs, which classified into plays all hydrocarbon reservoirs that had produced more than 10 Bcf of gas through 1986. Kosters and others (1989) defined 18 genetically related gas plays in the Permian Basin (Table 1 below) and summarized their geologic, engineering, and production characteristics. The plays were defined mainly on the basis of reservoir depositional setting; some plays were divided into subplays. Reservoirs in a play are related geologically and have similar production characteristics; thus, characteristics determined for the major reservoirs in a play can be extrapolated to volumetrically smaller and lesser known reservoirs within the same play (Kosters and others, 1989). Reservoir development methods that have been demonstrated to work well in one reservoir should be applicable to other reservoirs in the play.
We have updated the gas reservoir data base for the Permian Basin (Figure 2, below), adding smaller but significant-sized reservoirs having cumulative production greater than 6 Bcf through 1998 (Holtz and others, 1993; Dutton and others, 2000). (Gas reservoirs having production greater than 6 Bcf are referred to as "significant" in this paper. Approximately 6,000 cubic feet of gas equals 1 barrel of oil equivalent [BOE]; thus 6 Bcf is the equivalent of 1 million barrels of oil [USGS, 1995].) We identified 143 additional Permian Basin gas reservoirs not listed in the gas atlas that have produced more than 6 Bcf through December 31, 1998. In this paper, we classify these reservoirs into plays and map the expanded play boundaries.
Gas production data were obtained from the Railroad Commission of Texas 1998 Oil & Gas Annual Report (Railroad Commission of Texas, 1999); additional production information was derived from Dwights Energy Data. Information used to assign new reservoirs to geologic plays was primarily from the hearing files of the Railroad Commission of Texas.
Figure 2. Counties in the Permian Basin geologic province (modified from Galloway and others, 1983).
The 143 additional reservoirs having 6 Bcf cumulative production and not included in the Atlas of Major Texas Gas Reservoirs (Kosters and others, 1989) were assigned to plays and subplays. No new plays were identified; with the exception of just three reservoirs, the additional reservoirs produce from the plays defined by Kosters and others (1989). The 143 additional reservoirs expanded many of the play boundaries originally mapped by Kosters and others (1989). The expanded gas play boundaries for the Permian Basin are shown in the figures below.
The additional reservoirs are grouped by play and listed in alphabetical order by field and reservoir in the tables below. Information for each reservoir includes Railroad Commission reservoir number, Railroad Commission district (RRC), field name, reservoir name, county, discovery year, depth to top of reservoir (in feet), cumulative production through December 31, 1998 (in MMcf), and Bureau of Economic Geology play code (see table 1). For most of the reservoirs, the value for cumulative production shown in the tables is total production since reservoir discovery. Gas production data from the Railroad Commission of Texas (1999) includes only production since 1970. For old fields discovered before 1970, there can be significant pre-1970 production. Values for pre-1970 production were available for most of the reservoirs from Dwights Energy Data, with the exception of the 10 reservoirs noted by asterisks. These 10 reservoirs, which were all discovered before 1970, have actually produced more gas than is listed in the tables.
Click on each thumbnail picture to see an enlarged view.
Production data in the tables include both nonassociated gas and associated gas-well gas. Nonassociated gas is produced from reservoirs in which gas is the primary resource and little, if any, liquid hydrocarbon is produced (Kosters and others, 1989). Associated gas is produced from oil reservoirs and occurs as a gas cap in the reservoir (associated gas-well gas) or in solution in the oil (associated casinghead gas). Only associated gas-well gas is included in Table 2 (below), not associated casinghead gas. Cycling of produced gas (reinjection of gas into the reservoir for pressure maintenance) occurs in some oil reservoirs; thus, cumulative production figures may be imprecise. No adjustments for gas cycling were attempted in this project or the project of Kosters and others (1989).
Cumulative production from the 18 gas plays in the Permian Basin was 42.3 Tcf through 1986 (Kosters and others, 1989). Most of the reservoirs included in the Gas Atlas were discovered from the 1940s through the early 1970s. The plays with the highest production through 1986 were OR-1 Ellenburger Fractured Dolostone, SD-1 Siluro-Devonian CarbonateDeep Delaware and Val Verde Basins, and PM-4 San Andres and Grayburg Platform Carbonate (Table 2 above).
A majority of the reservoirs added to the data base in this study (82 of 143) were discovered after 1975. The two plays with the most production from these additional reservoirs, PN-5 Upper Pennsylvanian and Lower Permian Slope and Basinal Sandstone (479 Bcf) and PN-2 Strawn Group Shallow-Marine Carbonate (383 Bcf) (Table 2 above), were relatively less important in the gas atlas. The increase in production from these two plays reflects new discoveries in the deep Val Verde Basin. Only 5 of the 143 additional reservoirs have produced more than 60 Bcf, and 4 of them are in the Val Verde BasinMassie (Strawn), University 31 (Strawn Detrital), Ozona NE (Canyon), and Pakenham (Wolfcamp)in Crockett, Terrell, and Val Verde Counties. The other large reservoir is Haley (Morrow) in Loving County, which has produced 73 Bcf since 1983. Because this is the only significant Morrow gas reservoir in Texas, we have not established a new play, but the Morrow is an important oil and gas producer in the New Mexico part of the Delaware Basin (Grant and Foster, 1989). The plays with the greatest number of additional reservoirs are PN-5 Upper Pennsylvanian and Lower Permian Slope and Basinal Sandstone (30 reservoirs), SD-1 Siluro-Devonian CarbonateDeep Delaware and Val Verde Basins (21), PN-2 Strawn Group Shallow-Marine Carbonate (18), OR-1 Ellenburger Fractured Dolostone (14), and PN-1 Atoka Group Limestone and Sandstone (12) (Table 2 above).
Production from the Upper Pennsylvanian and Lower Permian Slope and Basinal Sandstone play comes from low-permeability sandstones that are generally referred to as Canyon sandstones (Dutton and others, 1993; Hamlin and others, 1995). Recent correlations and biostratigraphic data indicate that the Canyon sandstones are mainly in the Wolfcampian Series (Wuellner and others, 1986; Lehtonen, 1987; Hanson and others, 1991; Hamlin, 1999). The Ozona interval of the Canyon sandstones is composed largely of turbidite channels and lobes enclosed in muddy turbidite sheets (Hamlin, 1999). Productivity in Ozona Canyon reservoirs is controlled by original depositional reservoir quality modified by postdepositional diagenesis and natural fracturing. Most good wells are located in thick sandstone bodies composed of thick-bedded turbidites along the axes of channels and in the center of lobes (Hamlin, 1999). The Upper Pennsylvanian and Lower Permian Slope and Basinal Sandstone play in the Val Verde Basin was one of the most active gas-producing plays in the United States in the 1990s (Hamlin and others, 1995). In 1991, 24 percent of new completions in tight gas sandstones were made in this play (Hugman and others, 1993). More than 400 new Canyon gas wells were drilled in 1994 (Hamlin and others, 1995).
Most of the 143 additional significant gas reservoirs in the Permian Basin that have produced more than 6 Bcf through 1998 occur in the same plays that were defined in the Atlas of Major Texas Gas Reservoirs (Kosters and others, 1989). Production from reservoirs in the Val Verde Basin has increased in importance. Two plays, Upper Pennsylvanian and Lower Permian Slope and Basinal Sandstone and Strawn Group Shallow-Marine Carbonate, account for 39 percent of the 2.2 Tcf additional production.
This research was funded by the U.S. Geological Survey under Order No. 99CRSA1102. Andrew R. Scott and Chester M. Garrett, Jr., collected reservoir information at the Railroad Commission of Texas. Stephen C. Ruppel, Charles Kerans, and F. Jerry Lucia provided their expertise on Permian Basin geology and hydrocarbon production to the project, and Eugene M. Kim elucidated oil and gas production data bases. Their assistance is gratefully acknowledged. Drafting was by Jana Robinson of the Bureau of Economic Geology Graphics Staff under the direction of J. L. Lardon. Others contributing to this paper were Scarlett Hurt, word processing, and Susann Doenges, editing. Production of materials for publication to the Internet created by Scott Rodgers and Kerza Prewitt of the Bureau of Economic Geology Media Technologies Group. Publication was authorized by the Director, Bureau of Ecomic Geology, The University of Texas at Austin.
Dutton, S. P., Clift, S. J., Hamilton, D. S., Hamlin, H. S., Hentz, T. F., Howard, W. E., Akhter, M. S., and Laubach, S. E., 1993, Major low-permeability sandstone gas reservoirs in the continental United States: The University of Texas at Austin, Bureau of Economic Geology, Report of Investigations No. 211, 221 p.
Dutton, S. P., Zirczy, H. H., Tremblay, T. A., and Scott, A. R., 2000, Update of oil and gas reservoir data base, Permian and Fort Worth Basins, Texas: The University of Texas at Austin, Bureau of Economic Geology, final report prepared for the U.S. Geological Survey, 31 p. + data disk.
Galloway, W. E., Ewing, T. E., Garrett, C. M., Jr., Tyler, Noel, and Bebout, D. G., 1983, Atlas of major Texas oil reservoirs: The University of Texas at Austin, Bureau of Economic Geology, 139 p.
Grant, P. R., Jr., and Foster, R. W., 1989, Future petroleum provinces in New Mexicodiscovering new reserves: New Mexico Bureau of Mines & Mineral Resources, 94 p.
Hamlin, H. S., 1999, Syn-orogenic slope and basin depositional systems, Ozona Sandstone, Val Verde Basin, southwest Texas: The University of Texas at Austin, Ph.D. dissertation, 135 p.
Hamlin, H. S., Clift, S. J., Dutton, S. P., Hentz, T. F., and Laubach, S. E., 1995, Canyon sandstonesa geologically complex natural gas play in slope and basin facies, Val Verde Basin, southwest Texas: The University of Texas at Austin, Bureau of Economic Geology, Report of Investigations No. 232, 74 p.
Hanson, B. M., Powers, B. K., Garrett, C. M., Jr., McGookey, D. E., McGlasson, E. H., Horak, R. L., Mazzullo, S. J., Reid, A. M., Calhoun, G. G., Clendening, J., and Claxton, B., 1991, The Permian Basin, in H. J. Gluskoter, D. D. Rice, and R. B. Taylor, eds., Economic Geology, U.S.: Geological Society of America, The Geology of North America, v. P-2, p. 339356.
Holtz, M. H., Garrett, C. M., Jr., and Tremblay, T. A., 1993, Update of atlas of major Texas oil reservoirs data base and atlas of major Texas gas reservoirs data base: The University of Texas at Austin, Bureau of Economic Geology contract report prepared for the U.S. Geological Survey under Contract No. 1434-93-C-40079, 14 p. plus data tape.
Hugman, R. H., Springer, P. S., and Vidas, E. H., 1993, Tight gas field, reservoir, and completion analysis of the United States, volume 1: project summary: Arlington, Virginia, Energy and Environmental Analysis, topical report no. GRI-92/0226.1, prepared for the Gas Research Institute, variously paginated.
Kosters, E. C., Bebout, D. G., Seni, S. J., Garrett, C. M., Jr., Brown, L. F., Jr., Hamlin, H. S., Dutton, S. P., Ruppel, S. C., Finley, R. J., and Tyler, Noel, 1989, Atlas of major Texas gas reservoirs: The University of Texas at Austin, Bureau of Economic Geology, 161 p.
Lehtonen, L. R., 1987, Late Paleozoic evolution of the Val Verde Basin, West Texas: The University of Texas at El Paso, Masters thesis, 164 p.
Railroad Commission of Texas, 1999, 1998 Oil & Gas Annual Report, Volumes I and II: Austin, Texas, Railroad Commission of Texas Oil and Gas Division, 410 p. (v. I) and 513 p. (v. II).
Silver, B. A., and Todd, R. G., 1969, Permian cyclic strata, northern Midland and Delaware Basins, West Texas and southeastern New Mexico: American Association of Petroleum Geologists Bulletin, v. 53, p. 22232251.
U.S. Geological Survey, 1995, National assessment of United States oil and gas resources: U.S. Geological Survey Circular 1118, 20 p.
Wuellner, D. E., Lehtonen, L. R., and James, W. C., 1986, Sedimentary-tectonic development of the Marathon and Val Verde basins, West Texas, U.S.A.: a Permo-Carboniferous migrating foredeep, in P. A. Allen and P. Homewood, eds., Foreland Basins: International Association of Sedimentologists Special Publication 8, p. 347367.
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