HR: 16:15h
AN: H44C-02    [Abstracts]
TI: Airborne Electromagnetic Surveys Coupled With Hydrogeochemical Data to Enhance Near Surface Aquifer Investigations in an Area of Active Coalbed Natural Gas Production, Powder River Basin, Wyoming
AU: * Lipinski, B
EM: BAL17@pitt.edu
AF: Department of Geology and Planetary Science, University of Pittsburgh, Pittsburgh, PA 15260 United States
AU: Sams, J
EM: jsams@netl.doe.gov
AF: National Energy Technology Laboratory, 626 Cochrans Mill Rd, Pittsburgh, PA 15236 United States
AU: Harbert, W
EM: harbert@pitt.edu
AF: Department of Geology and Planetary Science, University of Pittsburgh, Pittsburgh, PA 15260 United States
AB: Assessing environmental effects from the disposal of water coproduced with coalbed natural gas (CBNG) in the Powder River Basin, Wyoming is complex. Over 30,000 CBNG wells are currently in production with another 30,000 to be installed within the next 20 years. Each well pumps between 100-400 barrels of water per day over an average operating life of seven years. Produced waters are generally of sodium-bicarbonate type with high sodium adsorption ratios and moderate salinity levels. A commonly used disposal method is through evaporation and infiltration impoundments. Downgradient subsurface hydrogeochemical changes are determined from groundwater monitoring wells. These methods are costly and provide limited data. Airborne electromagnetic (AEM) geophysical techniques present a viable alternative to current assessment protocols. Frequency domain AEM surveys were flown over an actively producing CBNG field along the Powder River in 2003 and 2004. Multifrequency inphase/quadrature responses were analyzed using Occam inversion techniques. Inversions were constrained using sounding specific starting models generated by the differential parameter method. Observed geochemical differences in the alluvial aquifer were successfully imaged using the geophysical data. Furthermore, geophysical responses interpreted as produced water mixing zones were consistent with results from strontium isotope data. AEM data will also be used to develop improved groundwater models. Discrete layer geoelectrical models derived from inversions yield depths that correlate with observed hydraulic head data. Additionally, AEM derived electrical conductivity distributions correspond to observed geomorphologic features allowing for delineation of hydrostratigraphic units. Results of this research are expected to provide policy makers with a better tool to manage impoundment permitting while also serving as an abundant source of data for groundwater model development and calibration.
DE: 1829 Groundwater hydrology
DE: 1835 Hydrogeophysics
DE: 1880 Water management (6334)
SC: Hydrology [H]
MN: Fall Meeting 2005