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Coalbed Methane Produced Water Disposal by Injection, PRB, MT

Lopez, David A. 1 (1) Montana Bureau of Mines and Geology, Billings, MT


Locally in the Powder River Basin, produced water associated with CBM development is of quality sufficient for domestic and livestock use but, it has high SAR values making it unsuitable for irrigation. Therefore, disposal methods must preserve beneficial use and cannot include the discharge of large volumes of water into streams that are used for irrigation. Because of these restraints, water disposed by injection must be in zones shallow enough to be tapped for use cost-effectively. The main goal of this project was to identify potential zones for disposal in the Tongue River Member of the Fort Union Formation (above the Lebo Shale Member). Of particular interest are thick porous and permeable channel sandstone units. In addition, deeper coal beds in the Tongue River Member may also be targets for injection if they are not being developed for CBM. This study was not intended to find injection targets capable of handling the disposal of all the produced water, but to use injection in conjunction with other approved methods to develop an economically and environmentally feasible disposal system.


Mapping and correlation of channel sandstones in the Tongue River Member have defined stacked north- and northeast-trending paleo-river systems. Some of the channel sandstones are more than 100 feet thick and have porosities as high as 30%. These sandstone bodies may prove to be excellent zones for injection of CBM producedwater, provided engineering problems regarding injecting into already water-saturated zones can be overcome.


AAPG Search and Discovery Article #90055©2006 AAPG Rocky Mountain Section Meeting, Billings, Montana