Assessment of undiscovered oil and gas resources of the Anadarko Basin Province of Oklahoma, Kansas, Texas, and Colorado

National Assessment of Oil and Gas Fact Sheet

The U.S. Geological Survey, using a geoscience-based assessment method ology, estimated mean technicallyrecoverable undiscovered continuous and conventional resources that total 495 million barrels of oil, 27.5 trillion cubic feet of natural gas, and 410 million barrels of natural gas liquids in the Anadarko Basin Province; this assessment includes the Las Animas arch area of southeastern Colorado. The province is at a mature stage of exploration and development for conventional resources. Mean undiscovered continuous resources are estimated at 79 percent of oil, 90 percent of natural gas, and 81 percent of natural gas liquids in the province.

Figure 1. Map showing boundaries of the Anadarko Basin Province (red line), the Woodford Composite total petroleum system (TPS), and the Pennsylvanian Composite TPS.

Introduction

The U.S. Geological Survey (USGS) in 2010 completed an assessment of the undiscovered oil and gas potential of the Anadarko Basin Province of western Oklahoma, western Kansas, northern Texas, and southeastern Colorado (fig. 1). The assessment is based on the geologic elements of each defined total petroleum system (TPS), including (1) hydrocarbon source rocks (source-rock richness and thermal maturation, hydrocarbon generation, adsorption, and migration); (2) reservoir rock type (conventional or continuous), distribution, and quality; and (3) types and distribution of reservoir traps and seals, including timing relative to petroleum generation and migration. Using this geologic framework, the USGS defined two TPSs, with 12 included assessment units (AU), and quantitatively estimated undiscovered oil, gas, and natural gas liquids resources in each AU (table 1).

The Anadarko Basin Province is in a mature state of exploration and development for conventional resources. Much of the production is reported as being commingled from numerous formations that were deposited over broad age ranges; this commingling influenced grouping of formations into the AUs. The Woodford Composite and Pennsylvanian Composite TPSs represent source rock input from numerous Ordovician through Pennsylvanian formations. The Woodford Composite TPS source rocks primarily contribute to Cambrian through Mississippian reservoirs, and those of the Pennsylvanian Composite TPS to Pennsylvanian and Permian reservoirs. Migration and accumulation of hydrocarbons from variable sources can occur along fault systems and updip from the extent of the Woodford Shale and other source rocks. Biogenic gas from the Cretaceous Niobrara Formation is produced from western Kansas and eastern Colorado; however, that resource was evaluated in the Denver Basin Province assessment (USGS Fact Sheet 002–03).

Resource Summary

The USGS assessment of undiscovered conventional and continuous (unconventional) resources within the province resulted in mean estimates of 495 million barrels of oil (MMBO), 27 trillion cubic feet of natural gas (TCFG), and 410 million barrels of natural gas liquids (MMBNGL) within twelve AUs in the two TPSs (table 1). Much of the remaining conventional resources are from field growth in this mature province. Continuous resources are focused in the deep part of the Anadarko Basin in Oklahoma and Texas. Boundaries of the Woodford Shale Oil and Woodford Shale Gas AUs and locations of sweet spots within them were based mainly on (1) extent and thickness of the formation, (2) filling of underlying Hunton Formation eroded channels, (3) historical and estimated ultimate production from existing wells, and (4) levels of thermal maturation based on 1D, 2D, and 3D petroleum system models and on vitrinite reflectance maps and data. The Thirteen Finger Limestone-Atoka Shale Gas continuous AU does not have documented production and has limited published information. Boundaries for this AU were based largely on characteristics such as thickness and lateral extent of included formations from well-log examination, and it is within the boundary of wet and dry gas generation based on 1D and 3D petroleum system models. This uncertainty is reflected in a fairly broad range of F5 to F95 resource estimates (table 1); mean undiscovered resources are 6.85 TCFG and 82 MMBNGL.

Table 1. Anadarko Basin Province assessment results listed by total petroleum system (TPS) and assessment unit (AU). Included are estimated volumes of undiscovered technically recoverable oil, gas, and natural gas liquids.

For Further Information

Supporting geologic studies of total petroleum systems and assessment units and reports on the methodology used in the Anadarko Basin Province assessment are in preparation. Assessment results and geologic reports will be available as completed at the USGS Web site http://energy.cr.usgs.gov/oilgas/noga/.

Anadarko Basin Province Assessment Team:

Debra K. Higley (Task Leader; higley@usgs.gov), Stephanie B. Gaswirth, Marvin M. Abbott, Ronald R. Charpentier, Troy A. Cook, Geoffrey S. Ellis, Nicholas J. Gianoutsos, Joseph R. Hatch, Timothy R. Klett, Philip Nelson, Mark J. Pawlewicz, Ofori N. Pearson, Richard M. Pollastro, and Christopher J. Schenk (National Assessment of Oil and Gas Project Chief).

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