HR: 16:45h
AN: H32G-04    [PDF]
TI: Organic and Inorganic Species in CBM Produced Water: Implications for Water Management Strategies
AU: * Kharaka, Y K
EM: ykharaka@usgs.gov
AF: U. S. Geological Survey, MS/427 345 Middlefield Rd., Menlo Park, CA 94025 United States
AU: Rice, C A
EM: crice@usgs.gov
AF: U. S. Geological Survey, Denver Federal Center, Denver, CO 80225 United States
AB: Coal-bed methane (CBM) wells currently produce close to one billion bbl of water annually and deliver about 8% of total natural gas in the USA. The salinity of this produced water generally is lower than that of water from conventional petroleum wells; salinity commonly is 1,000-20,000 mg/L, but ranges from 200 to 150,000 mg/L TDS. Most CBM wells produce Na-HCO3-Cl type water that is low in trace metals and has no reported NORMs. This water generally has no oil and grease and has relatively low (2-10 mg/L) dissolved organic carbon (DOC), but its organic composition has not been characterized in detail. The water is disposed of by injection into saline aquifers, through evaporation and/or percolation in disposal pits, road spreading, and surface discharge. Water that has low ($<$1,000 mg/L TDS) salinity and sodium adsorption ratio (SAR) is considered acceptable for irrigation, surface discharge and for injection into freshwater aquifers. Because groundwater associated with coal, especially with lignite and subbituminous coal, is known to contain a variety of toxic or potentially toxic organics, including hydroxyphenols and PAHs, the organic and inorganic compositions of CBM waters should be systematically characterized and their potential for harm to human health, crops and the environment carefully evaluated prior to its addition to existing water supplies. As an alternative to costly disposal, lower salinity produced water from high-yield CBM wells is being considered for reclamation. The treated water would be a valuable new water resource, especially in the arid western USA. The feasibility and cost of reclaiming produced water to meet irrigation, industrial and drinking water standards was evaluated in a 10 gpm pilot field study. The estimated treatment cost was high at about $0.39/bbl ($3,000/acre-ft) for potable water, but would be substantially lower and competitive for irrigation and industrial uses in some arid regions of the USA.
DE: 1045 Low-temperature geochemistry
DE: 1055 Organic geochemistry
DE: 1803 Anthropogenic effects
DE: 1831 Groundwater quality
DE: 1878 Water/energy interactions
SC: Hydrology [H]
MN: 2003 Fall Meeting