Management and Effects of Coalbed Methane Produced Water in the Western United States (2010) / Chapter Skim
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From page 1... ...
CBM produced water management can be challenging for regulatory agencies, CBM well operators, water treatment companies, policy makers, landowners, and the public because of differences in the quality and quantity of produced water; available infrastructure; costs to treat, store, and transport produced water; and states' legal consideration of water and produced water. Some states consider produced water as waste, whereas others consider it a beneficial byproduct of methane production.
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From page 2... ...
S . on the environment, and the degree of connectivity among water-bearing coalbeds, other groundwater aquifers, and surface water; • potential beneficial uses of CBM produced water and costs for various water treat ment, storage, or use strategies; • documented and potential effects of CBM produced water on surface and ground water resources, soil, and ecological systems and ways in which those effects could be monitored and mitigated; and • challenges in the existing regulatory framework for CBM produced water management.
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From page 3... ...
The high porosity and permeability in Powder River coalbeds also require larger volumes of water to be withdrawn by the CBM well operator to stimulate methane release from the coal, compared to the other western CBM basins. Large volumes of relatively fresh CBM produced water from the Powder River Basin are then primarily managed through discharge to surface storage impoundments or to ephemeral and perennial streams and rivers, with or without treatment to meet regulatory requirements.
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From page 4... ...
Lack of knowledge of the age of CBM produced water contributes to uncertainty in understanding the consequences of long-term produced water withdrawals to other aquifers. At present, the "age" of CBM produced water and consideration of fossil CBM produced water as a nonrenewable resource are not currently factored into decisions about produced water management strategies.
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From page 5... ...
ENVIRONMENTAL EFFECTS OF CBM PRODUCED WATER Concerns about environmental effects associated with CBM production and produced water management relate primarily to short- and long-term consequences of (1) groundwater depletion and drawdown associated with water pumping during CBM extraction, and (2)
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From page 6... ...
In surface impoundments containing CBM produced water, infiltration and percolation of produced water can dissolve and mobilize preexisting salts or naturally occurring constituents such as sulfate, selenium, arsenic, manganese, barium, chloride, nitrate, and total dissolved solids in soils below the impoundments. In the Powder River Basin of Wyoming where impoundments provide the primary management method for CBM produced water, groundwater monitoring showed increased levels of total dissolved solids (TDS)
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From page 7... ...
Physical effects to ephemeral or perennial streams and rivers, such as bank scouring, increased bottom sedimentation, or channel erosion due to unmanaged and/or unregulated CBM produced water discharge have occurred in the Powder River and the Raton basins. Regulatory authorities have required operators to control and discontinue practices or events contributing to these circumstances, and the committee supports all efforts to prevent unmanaged and unregulated releases of CBM produced water.
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From page 8... ...
Published research using isotope ratios of solutes in CBM produced water has shown that isotopic "fingerprints" of CBM water in receiving streams and rivers have changed as a result of CBM produced water discharge and may be more effective in monitoring and assessing CBM produced water influence on surface water and groundwater resources. An array of chemical parameters, including major, minor, and trace constituents and isotopes, should be used to evaluate the potential effects of CBM discharges on stream water quality.
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From page 9... ...
REGULATORY FRAMEWORK FOR CBM PRODUCED WATER MANAGEMENT At the federal level, the requirements associated with leasing and permitting CBM operations on federally managed public lands through the BLM and the protection of water resources under the jurisdiction of the Environmental Protection Agency (EPA) are relatively broad but clear.
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From page 10... ...
Multiple potential users and uses of limited water resources, a concern by the public for protection of these limited resources, the complexities of hy drogeological systems, and the renewability or nonrenewability of water resources require increasingly sophisticated approaches to understanding CBM produced water and produced water management. These approaches require a basis in scientifically grounded studies and consistent monitoring, and should allow for a greater range of economically and environmentally viable options for CBM produced water management in the future.
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