Field and Laboratory Investigation of Coalbed Natural Gas Co-Produced Water and Its Effects On Salinity and Sodicity In Powder River Basin Soils In Wyoming.

Water coproduced from coal seams during natural gas extraction (i.e., CBNG water) can be an environmental concern in the Powder River Basin (PRB), Wyoming. In order to better understand how PRB soils and natural waters are impacted from land applications and/or discharges of CBNG waters, chemical constituent analyses, hydraulic properties associated with infiltration and hydraulic conductivity, and use of stable isotopes will be conducted to determine soil-water responses. Field and laboratory investigations will be performed for this research. Saturated and unsaturated hydraulic conductivities will be measured in the field with large field tension infiltrometers using representative irrigation water from Sheridan Wyoming area with known chemical parameters as well as both actual and simulated CBNG waters with variable EC and SAR levels. Soil samples will be taken with a 15 (d) x 10 (h) cm corer and transported back to the laboratory. Water samples collected from CBNG wellheads, rivers mixing with wellheads, irrigation ditches, ponds and undisturbed waters will be analyzed for pH, EC, DOC, major ions, and d¹³C-DIC. Following field studies, saturated and unsaturated hydraulic conductivities of the soil cores will be measured in the laboratory with several simulated waters using the constant head method with tension infiltrometers. Leachates from the soil cores will be analyzed for pH, EC, DOC, and major ions. An isotope batch adsorption study will be conducted using CBNG water and disturbed PRB soils. The d¹³C-DIC of the water samples will be measured before and after mixing with the soil. The batch study results will then lead to laboratory isotope leaching experiments.