Coalbed Methane Produced Water Management Guide Treatment And Discharge To Surface Waters

In some coalbeds, naturally occurring water pressure holds methane-the main component of natural gas-fixed to coal surfaces and within the coal. In a coalbed methane (CBM) well, pumping water from the coalbeds lowers this pressure, facilitating the release of methane from the coal for extraction and use as an energy source. Water pumped from coalbeds during this process-CBM 'produced water'-is managed through some combination of treatment, disposal, storage, or use, subject to compliance with federal and state regulations. 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. Thus, although current technologies allow CBM produced water to be treated to any desired water quality, the majority of CBM produced water is presently being disposed of at least cost rather than put to beneficial use. This book specifically examines the Powder River, San Juan, Raton, Piceance, and Uinta CBM basins in the states of Montana, Wyoming, Colorado, New Mexico, and Utah. The conclusions and recommendations identify gaps in data and information, potential beneficial uses of CBM produced water and associated costs, and challenges in the existing regulatory framework.

Produced water contributes to the largest volume waste stream associated with oil and gas (O&G) exploration and production (E&P) operations. It is usually a complex mixture of inorganics and organics that is formed underground and brought to the surface during O&G production. Traditionally, produced water has been considered as a waste to the O&G industry. The conventional management strategies include disposal (typically by injection into depleted wells or permitted disposal wells), recycle (direct reuse within the E&P operation), and reuse (treatment and reuse offsite for food crop irrigation, livestock watering or industrial use). The O&G industry is going through a paradigm shift, where scarcity of water, economics of water management, declining oil costs, and increasing focus on environmental and ecological stewardship are shifting the focus toward integrated water management in E&P operations. Water is no longer a problem to be delegated to a third-party disposal or treatment vendor, but is becoming a cornerstone of O&G production. In this review, we summarize produced water characteristics, regulations and management options, produced water treatment fundamentals, and a detailed discussion of process equipment and advantages/disadvantages of currently available treatment processes. These results in peer-reviewed publications could provide a guide for the selection of appropriate technologies based on the desired application. Major research efforts in the future could focus on the optimization of current technologies and use of combined treatment processes of produced water in order to comply with reuse and discharge limits, under more stringent environmental regulations.

The purpose of this report is to (1) summarize water quality and biomonitoring studies of coal-seam produced waters in Alabama; and (2) to present a monitoring approach for evaluating the risk, and acceptability of surface discharge for certain produced waters. The integrated monitoring approach, termed the Cedar Cove model, was developed for produced waters derived from the development of methane from coal seams in Alabama. The integrated monitoring approach consists of chemical-specific effluent monitoring, toxicological evaluation of the produced water, instream bioassessment, and continual water-quality monitoring of the receiving stream.