Surface to Subsurface Correlation of Methane-Producing Coals, Northeast Oklahoma Shelf Area

L. A. Hemish
Oklahoma Geological Survey, Norman, OK ([email protected])

Coalbed-methane production has been reported by operators from 10 named Pennsylvanian (Desmoinesian) coals in the northeast Oklahoma shelf area. They are (from oldest to youngest): the Riverton (McAlester Formation); Rowe, Drywood (Savanna Formation); Bluejacket (Boggy Formation); Weir-Pittsburg, Croweburg, Bevier, Iron Post, Mulky (Senora Formation); and Dawson (Holdenville Formation). Most of the production is from wells located in Nowata, Osage, Rogers, Tulsa, and Washington counties.

A subsurface stratigraphic framework, based primarily on gamma, density, and neutron well logs and core-hole logs, is established to assist operators in correctly identifying methane-producing coal beds. About 50 high-quality well logs (from the more than 200 examined) were used to construct five cross sections. Three east-west cross sections are oriented approximately parallel to present-day dip and extend about 60 miles west from the coal outcrop belt across Ts. 22, 25, and 28 N. Two north-south cross sections are oriented approximately parallel to present-day strike and extend about 50 miles from the Kansas-Oklahoma state line south to T.20N.

Persistent markers such as the Oologah Limestone (Big lime); the Fort Scott Limestone (Oswego lime); the Verdigris Limestone; the Tiawah Limestone (Pink lime); and others were used as reference strata to correlate the coal beds. A composite type log is designated for a site centrally located in the methane-producing shelf area. It shows the important marker beds (limestones, black shales, and persistent sandstones), as well as the stratigraphic positions of named coals.

AAPG Search and Discovery Article #90903©2001 AAPG Mid-Continent Meeting, Amarillo, Texas