Expansion of Gas Reservoir Data Base, Permian Basin, Texas
Shirley P. Dutton, Mark H. Holtz, Thomas A. Tremblay, and Helena H. Zirczy
Bureau of Economic Geology, The University of Texas at Austin, Austin, Texas
ABSTRACT
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 Carbonate—Deep
Delaware and Val Verde Basins (21), Strawn Group Shallow-Marine Carbonate (18),
Ellenburger Fractured Dolostone (14), and Atoka Group Limestone and Sandstone (12).
INTRODUCTION
This paper updates the data base of major gas reservoirs in the Permian Basin (Figure 1)
compiled by Kosters and others (1989). The original delineation of gas plays in Texas
1
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) 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, 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 Dwight’s Energy Data. Information used to assign new
reservoirs to geologic plays was primarily from the hearing files of the Railroad
Commission of Texas.
2
GAS RESERVOIR DATA BASE
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 (Table 2). 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 Figures 2–4.
The additional reservoirs are grouped by play and listed in alphabetical order by field and
reservoir in Table 2. 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. For most of
the reservoirs, the value for cumulative production shown in Table 2 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 Dwight’s 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 Table 2.
Production data in Table 2 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
3
gas) or in solution in the oil (associated casinghead gas). Only associated gas-well gas is
included in Table 2, 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).
PERMIAN BASIN GAS PLAYS
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
Carbonate—Deep Delaware and Val Verde Basins, and PM-4 San Andres and Grayburg
Platform Carbonate (Table 3).
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 3), 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 Basin—
Massie (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
4
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 Carbonate—Deep 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).
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).
5
CONCLUSIONS
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.
ACKNOWLEDGMENTS
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 the Graphics staff of the Bureau
of Economic Geology under the direction of J. L. Lardon. Others contributing to this
paper were Scarlett Hurt, word processing, and Susann Doenges, editing.
REFERENCES
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.
6
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 Mexico—
discovering 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
sandstones—a 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
7
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. 339–356.
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, Master’s thesis, 164 p.
8
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).
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 PermoCarboniferous migrating foredeep, in P. A. Allen and P. Homewood, eds., Foreland
Basins: International Association of Sedimentologists Special Publication 8, p.
347–367.
9
Figure Captions
Figure 1. Counties in the Permian Basin geologic province (modified from Galloway and
others, 1983).
Figure 2. Pre-Pennsylvanian gas plays in the Permian Basin. (a) Ordovician and
Mississippian plays. (b) Siluro-Devonian plays.
Figure 3. Pennsylvanian gas plays in the Permian Basin. (a) Atoka and Strawn Group
plays. (b) Upper Pennsylvanian plays.
Figure 4. Permian gas plays in the Permian Basin. (a) Wolfcampian and Leonardian
plays. (b) Guadalupian plays.
10