Coalbed Methane Development in PEL 238, Gunnedah Basin, New South Wales, Australia

David Decker¹, Dennis Morton², and Brenton Smith^2
1 First Source Energy Group, Evergreen, CO
² Eastern Star Gas, Sydney, Australia

The Gunnedah Basin is located in north-eastern New South Wales, between the Sydney Basin to the south and the Surat Basin to the north. The basin contains up to 3,700 feet of Permian and Triassic sediments overlying volcanic basement rocks. PEL 238, roughly two million acres is size, lies in the central portion of the Gunnedah Basin.

The Early Permian Maules Creek and Late Permian Black Jack Coal Measures account for most of the coal resources in the Gunnedah Basin. Individual coal seams within the two coal measures are thick, laterally continuous and pervasively gas-bearing. Regional studies indicate there is an estimated 35 TCF GIP housed within coal sequences of PEL 238. The basal coal seam, the Bohena seam, of the Maules Creek Coal Measures is the main focus of coalbed methane development in PEL 238.

Regional exploratory drilling has isolated a development platform of approximately 100 sq. miles in size. Three pilot wells located in the north, central and southern portion of the development area were cored and extensively tested. Data collected from the three wells was encouraging. The Bohena seam, continuous between pilot wells, is 16 to 45 feet thick. Permeability varies between 11 and 35md at depths of 2,900 feet. Gas contents, on an as received basis range between 464 and 525 scf/t. Isotherm analysis indicates the coals are fully gas saturated. Individual well stabilized post stimulation production rates are 500 to 850 bwpd and 25 to 60 mcf/d. In 2006 a nine spot dewatering program is planned for the southern pilot area.