The Producibility of Coalbed Methane from Wilcox Coals in Louisiana
J. B. Echols
Louisiana Geological Survey, Baton Rouge, LA
The producibility model for coalbed methane contains six controls. They are: 1) Gas Content, 2) Permeability, 3) Tectonic and Structural Setting, 4) Depositional Setting, 5) Hydrology, and 6) Coal Rank and Gas Generation.
Gas Content in Wilcox coals in Louisiana was proven in 1989 when Torch Operating Company perforated the No. 3 Greer well Sec. 21, T14N-R4E. The well immediately flowed gas (50,000cfg and 65 bbls water). The well flowed approximately 2.8 million cfg over three months and was plugged.
Permeability is indicated by separation (approximately 2 ohms) of the 16'' short normal and the 40'' conductivity curves in e-logs. Tectonic and Structural Setting: The potential area of interest is situated between the Sabine Uplift and LaSalle Arch on the westsouthwest, the D’Arbonne Platform on the northwest, and the Monroe Uplift on the northeast. This location effected control on the Wilcox depositional environments.
Depositional Setting: The coals in this area were deposited on top of abandoned earlier deltas.
Hydrology: These coals do not outcrop at the surface, and are not charged with percolating ground water which must be removed during production. The thick Cane River shale section overlying the Wilcox separates the brackish and fresh water sands of the Sparta and Cockfield from the saline waters of the Wilcox.
Coal Rank and Generation: Cores taken in equivalent sections in Concordia Parish, Louisiana, reveal a vitrinite reflectance value of Ro = .45 :a coal rank of lignite to subbituminous.
AAPG Search and Discovery Article #90901©2001 GCAGS, Annual Meeting, Shreveport, Louisiana