Relationship Between Gas and Water Production and Structure inSoutheastern Deerlick Creek Coalbed Methane Field, Black Warriorbasin, Alabama

摘要

Map-scale structure exerts a significant control on the magnitude and distribution of fluid production in theDeerlick Creek coalbed methane field. In this area an exceptional gas producing well is usually an exceptional waterproducer but an exceptional water well is not necessarily an exceptional gas well. Of the 7 most productive gaswells, 5 (71%) are among the highest producing water wells. Gas production is generally poor in the southwesternpart of the area where the maturation level of the coal is at the edge of or below the thermogenic gas window. Faultsare zones of low water and gas production and segment the reservoir into blocks having significantly differentproductivity. The two most transmissive gas- and water-producing fault blocks are both half grabens, the eastern ofwhich is the better gas producer, presumably because it is in an area of higher thermal maturity. The horst and fullgraben are the poorest producers of gas and water in the area where the coal is thermally mature. This suggests thatmoderate deformation (half grabens) may enhance fracture transmissivity relative to areas of no deformation (thehorst), and that too much deformation (the full graben) reduces transmissivity.