Geochemistry of Coalbed Natural Gas (CBNG) Produced Water in Powder River Basin, Wyoming: Salinity and Sodicity
- First Online:
- 252 Downloads
Extraction of natural gas from a confined coal aquifer requires the pumping of large amounts of groundwater, commonly referred to as produced water. Produced water from the extraction of coalbed natural gas is typically disposed into nearby constructed discharge ponds. The objective of this study was to collect produced water samples at outfalls and corresponding discharge ponds and monitor pH, electrical conductivity (EC), calcium (Ca), magnesium (Mg), sodium (Na), and alkalinity. Outfalls and corresponding discharge ponds were sampled from five different watersheds including Cheyenne River (CHR), Belle Fourche River (BFR), Little Powder River (LPR), Powder River (PR), and Tongue River (TR) within the Powder River Basin (PRB), Wyoming from 2003 to 2005. From Na, Ca, and Mg measurements, sodium adsorption ratios (SAR) were calculated, and used in a regression model. Results suggest that outfalls are chemically different from corresponding discharge ponds. Sodium, alkalinity, and pH all tend to increase, possibly due to environmental factors such as evaporation, while Ca decreased from outfalls to associated discharge ponds due to calcite precipitation. Watersheds examined in this study were chemically different form each other and most discharge ponds with in individual watersheds tended to increase in Na and SAR from 2003 to 2005. Since discharge pond water was chemically changing as a function of watershed chemistry, we predicted SAR of discharge pond water using a regression model. The predicted discharge pond water results suggested a high correlation (R2 = 0.83) to discharge well SAR. Overall, results of this study will be useful for landowners, water quality managers, and industry in properly managing produced water from the natural gas extraction.
KeywordsNatural gas CBNG produced waters Salts Sodium Adsorption Ratio Sodicity Salinity Irrigation
- American Public Health Association. (1992). Standard methods for the examination of water and wastewater. Washington, DC: American Public Health Association.Google Scholar
- Brown, D. S., & Allison, J. D. (1992). MINTEQA2: An equilibrium metal speciation model. Athens, Georgia: Environmental Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency.Google Scholar
- Chatterjee, S., Hadi, A. S., & Price, B. (2000). Regression analysis by example (3rd ed., pp. 204–216). New York: Wiley.Google Scholar
- DeBruin, R. H., Lyman, R. M., Jones, R. W., & Cook, L. W. (2000). Coalbed methane development in Wyoming. Information pamphlet number 7. Laramie, WY: Wyoming State Geological Survey.Google Scholar
- Drever, J. I. (1997). The geochemistry of natural waters, surface and groundwater environments (pp. 41–58). Englewood Cliffs, NJ: Prentice-Hall.Google Scholar
- Hanson, B., Grattan, S. R., & Fulton, A. (1993). Agricultural salinity and drainage: A handbook for water managers. Davis, CA: University of California Irrigation Program, University of California.Google Scholar
- Minitab. (2000). MINITAB 13.1. State College, PA: Minitab, Inc.Google Scholar
- Rice, C. A., Ellis, M. S., & Bullock, J. H. Jr. (2000). Water co-produced with coalbed methane in the Powder River Basin, Wyoming: Preliminary compositional data. Open-File Report 00-372. Denver, CO: U.S. Geological Survey.Google Scholar
- Ruckelshaus Institute of Environment and Natural Resources (RIENR). (2005). Water production from coalbed methane development in Wyoming: A summary of quantity, quality and management. Final Report to Wyoming State Governor. Retrieved from http://www.uwyo.edu/enr/ienr/cbm.asp.
- SAS (SAS Institute). (2000). SAS proprietary software release 9.0. Raleigh, NC: SAS Institute.Google Scholar
- Strumm, W., & Morgan, J. J. (1996). Aquatic chemistry, chemical equilibria and rates in natural waters (3rd ed., p. 591). Canada: Wiley.Google Scholar
- U.S. Department of Interior, Bureau of Land Management. (2003). Final environmental impact statement and proposed plan amendment for the Powder River Basin oil and gas project. Volumes 1–3. Buffalo, WY: Buffalo Field Office.Google Scholar
- U.S. Department of Interior, Geological Survey. (1986). Hydrology of area 50, Northern Great Plains and Rocky Mountain Coal Provinces, Wyoming and Montana. Water Resources Investigations Open-File Report 83–545.Google Scholar
- Wyoming Department of Environmental Quality. (2001). SAP: Water quality rules and regulations, chapter 1. Cheyenne, WY: Department of Environmental Quality and Water Quality Division.Google Scholar
- Wyoming Department of Environmental Quality. (2006). NPDES Permitting, Water Quality Division. Retrieved 1/11/06, from http://deq.state.wy.us/wqd/npdes/.