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Belden & Blake Corporation Coalbed Methane Operations in the Northern Latrobe Syncline, Indiana and Westmoreland County, Southwestern Pennsylvania, Blacklick and Derry Fields; Structural and Stratigraphic Factors Influencing Production

Miller, John F.
Belden & Blake Corporation, North Canton, OH

BBC has been drilling and producing CBM since 1994 in Latrobe Syncline in Indiana and Westmoreland Co., Southwestern Pennsylvania. The Blacklick and Derry Fields consist of 118 wells that produce from seams in the Conemaugh, Allegheny, and Pottsville Groups. There are generally 3-6 seams completed in individual wells with net completed thickness per well ranging from 6-15 feet at a depth of 400-1200 feet.

The Blacklick Field is at the northern termination of the Latrobe syncline where the NE tending structure is cross cut by a NW tending Cross Strike Discontinuity (CSD). The CSD is associated with increases in coal thickness in the Upper Freeport, Middle Kittanning, and Clarion coal seams. The CSD may also enhance the cleat development. EUR numbers within the Blacklick field sweet spot are generally double the numbers in the remaining field (Average EUR of 280-620 MMCF versus normal 100-250 MMCF). The Middle Kittanning and Clarion coal thickness appear to correlate very well with increased production.

Derry Field to the south of Blacklick has similar net coal thickness but drastically different production (EUR’s below 50 MMCF). Cores were taken in Blacklick and Derry Fields to compare the gas content values. The core in Blacklick has an overall gas content average of 209 scf/ton (Bevilaqua #1), and in Derry the average is 200 scf/ton (Smith Family #3). The similar gas contents indicate that increased fracture porosity due to the CSD in Blacklick may be important for deliverability of the gas from the coal matrix.

AAPG Search and Discovery Article #90031©2004 AAPG Eastern Section Meeting, Columbus, Ohio, October 3-5, 2004