Understanding CBM Produced Water Quality Variability to Design Treatment Processes for Beneficial Use

Coalbed methane (CBM) is an unconventional gas resource with large worldwide reserves that has environmental impacts from disposal of substantial amounts of co-produced, highly saline water. Industry treats co-produced water as a waste product. Utilizing this water for beneficial uses, such as irrigation, stream flow and drinking water augmentation, is hindered by lack of knowledge about water quality and regional variations in water quality. Regions in the US where CBM occurs in substantive extractable quantities also are regions experiencing great stress from water shortages. Colorado School of Mines is funded through the Department of Energy (DOE) program Research Partnership to Secure Energy for America (RPSEA) to develop an integrated decision framework to provide guidance to the gas industry in selecting a strategy for management and treatment of produced water from CBM and gas shale operations. To develop this framework for produced water management, research efforts are currently focused on the characterization of the variability and range of water quality. Water quality information from CBM producing wells in the Rocky Mountain Region is utilized in an attempt to correlate water quality with geographic location, geologic formation, and commonly occurring constituents. In addition to spatial variability, the database also includes estimations of variability with time and water quantity produced. A thorough analysis of water quality applied to the framework of mapped and correlated systems will help the gas industry in predicting water quality in current producing wells, and also for potential wells they are interested in drilling. The database is accessible to producers and interested parties through the Water Quality Module (WQM) developed by the aforementioned RPSEA project. The WQM provides information on a comprehensive list of constituents and their basin variability, essential info to develop treatment processes capable of utilizing produced water for beneficial use.