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Shale Gas Water Lifecycle: Water Lifecycle Issues

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  • Withdrawal:  Access to supply sources, timing, permitting, compliance and reporting
  • Transport:  Transport options (truck, pipeline, rail), environmental and best practices, cost, timing
  • Storage:  Cost, surface disturbance, permitting
  • Drilling and Fracturing:  Surface handling, produced water mgmt
  • Treatment:  Benefit, cost, volume of resulting concentrate
  • Reuse/Recycle:  Reuse for HF, other markets for recycled water, demand characteristics (quantity, quality, timing)
  • Disposal:  Availability/permitting of injection zones, capacity at commercial/municipal plants, discharge permits, compliance



    Natural gas production from hydrocarbon rich shale formations, known as “shale gas,” is one of the most rapidly expanding trends in onshore domestic oil and gas exploration and production today (GWPC and ALL Consulting, 2009).  Tremendous natural gas resource potential has been identified in shale basins across the U.S., with one of the largest being the Marcellus Shale in the Appalachian Basin.  Recoverable gas resources in the Marcellus are estimated to exceed 300 trillion cubic feet (Esch, 2008).

    As shale gas development has proceeded in the Marcellus area, which includes parts of New York, Pennsylvania, and West Virginia, probably the biggest environmental issue that has been identified is water supply, use, and disposal.  Water issues may threaten to significantly delay or slow development of this important resource (BradyDale, 2008; Corio, 2008; Lustgarten, 2008).  In New York, permitting for horizontal shale gas wells and wells using large volume hydraulic fracturing has been halted pending the completion of a Supplemental Generic Environmental Impact Statement under that state’s environmental law.  Many of the issues being addressed in that Statement are water-related (NY DEC, 2009).
     
    Shale gas has become economically producible principally due to advancements in two technologies:  horizontal drilling and large volume hydraulic fracturing.  The amount of water needed to drill and fracture a horizontal shale gas well generally ranges from about 2 million to 4 million gallons, depending on the formation characteristics.  With potentially hundreds of wells to be drilled each year as development proceeds, the water demands can be significant, although they collectively represent less than one percent of total water demand in the region (SRBC, 2008).
     
    The water management lifecycle for shale gas wells has several phases.  First, the water supply must be obtained, either from surface or ground water sources possibly augmented by recycled or waste water.  That water must then be transported to and stored at or near well sites.  While some of this water is used in the drilling process, the bulk of the fresh water used is mixed with small amounts of chemical additives and pumped under pressure into the subsurface to hydraulically fracture the rock and allow the gas to flow to the well.  Thirty to seventy percent of the fracture water is produced back up the well bore and must be disposed of in an approved manner, generally through underground injection, treatment and discharge to surface waters, or recycled for additional fracturing operations or other industrial uses.
     
    Every step of this water lifecycle is regulated.  In the Marcellus region, two river basin commissions, the Susquehanna River Basin Commission (SRBC) and the Delaware River Basin Commission (DRBC) permit withdrawals from the surface waters of their respective basins.  Although they work closely with the states, they are independent regulatory bodies and may limit water volumes and withdrawal locations both volumetrically and seasonally.

    The public, non-governmental organizations (NGOs), politicians, and government agencies have expressed great concern about water use and disposal associated with shale gas development.  One issue is the sheer volume of water used and the resulting impact on regional water supplies and environmental values, such as aquatic species and wetlands.  There is also concern about the chemicals that are added to fracturing fluid, which, while only about 1 percent of the total volume, have raised concerns about their impact on health and the environment as some portion remains underground following well stimulation and the remainder must be treated for disposal or reuse.  The result is an evolving regulatory regime that impacts both producers and regulators, adding costs and uncertainty for both.  A large part of the uncertainty is associated with not having sufficient information on the whole lifecycle of water that is used in the shale gas development process.  Operators need to plan for adequate water supplies and disposal options for all of their wells over a period of several years.  Regulators have a great need for tools that will help them understand, forecast, and plan for future activity, and to analyze the impacts of all of the development that will be occurring in an area. 

    In addition, water management practices in the Marcellus region are evolving as development accelerates and constraints are becoming apparent.  For example, because there is limited water treatment and disposal capacity in the region, producers are increasingly investigating recycling and reuse opportunities.  Water transport options are also being scrutinized because the cost of transporting water, both fresh water and used water, can exceed the cost of the water itself.  Thus, more producers are putting in temporary pipelines to substitute for more expensive trucking.  One producer is using rail cars to transport produced water to injection wells.  This changing situation requires quick analysis and decision making to keep abreast of circumstances, minimize costs, and manage water use effectively.