Region: Northern Midcontinent Denver Basin Province This description of the Denver Basin Province is from the U. S. Geological Survey 1995 National Assessment of United States Oil and Gas Resources (available on CD-ROM from the U.S.G.S. as Digital Data Series DDS-30, Release 2).

Denver Basin Province

Introduction

The Denver Basin Province is an asymmetrical Laramide-age structural basin located in eastern Colorado, southeastern Wyoming, the southwestern corner of South Dakota, and the Nebraska Panhandle. Two basin deeps located along the axis of the basin, close to the Front Range, separate the steeply dipping western flank and gently dipping eastern flank. The basin is bounded on the west by the Front Range of the Rocky Mountains, on the northwest by the Hartville Uplift, on the northeast by the Chadron Arch, and on the southwest and southeast by the Apishapa Uplift and Las Animas Arch, respectively.

The primary producing plays in this province are the Dakota Group (Combined D and J Sandstones) Play, and the J Sandstone Deep Gas (Wattenberg) Play. Approximately 90 percent of the 800 MMBO and 1.2 TCFG produced from the basin has been from the J sandstone (Land and Weimer, 1978, Tainter, 1984). These two plays include 180 oil accumulations containing 1 or more MMBO. Eighteen fields have produced 6 BCFG or more (Hemborg, 1993d). Half of the province's 1.2 TCFG has been produced from the Wattenberg field; this field was discovered in 1970 and has produced about 0.63 TCFG and 2.2 MMBO from the J sandstone, Codell Sandstone, and Sussex (Terry) Sandstone. The largest oil field in the Denver Basin is Adena with more than 62 MMBO produced from the J and D sandstones and estimated ultimate recoverable of 62.5 MMBO.

Primary trapping mechanisms in most Denver Basin plays are stratigraphic and, secondarily, a combination of stratigraphy and minor structures. Stratigraphic traps are mainly facies change and updip pinch-out of reservoir intervals. Play assignments were determined based on producing age and formations, trapping mechanisms, and petroleum production characteristics.

Acknowledgments

Scientists affiliated with the American Association of Petroleum Geologists and from various State geological surveys contributed significantly to play concepts and definitions. Their contributions are gratefully acknowledged.

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