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Lifecycle of Water Use
Exploration & Site Construction
During this phase of development, water is used primarily for dust control on access roads and equipment cleaning. The amounts used are relatively small and this use is similar to other construction projects.
Drilling & Completion
The majority of water use in oil and gas development occurs during the drilling and completion phase. Well stimulation methods - hydraulic fracturing & water flooding - are the largest use. The second largest use is for drilling with water-based drilling muds. A relatively small amount of water is also used for equipment cleaning & when cementing well casing in the bore hole.
Reclamation & Abandonment
During the end a development's lifespan amounts of water used are minimal. Potential uses will be for cement plugging of the well and reclamation activities.
Water Recycling and Reuse
Reducing the amount of fresh water used in oil and gas development includes reusing and recycling water where possible. How much water can be reused on the well site, for new wells in the area or for other uses depends, in part, on water quality considerations.
"Produced Water Beneficial Use Dialogue: Opportunities and Challenges for Re-Use of Produced Water on Colorado's Western Slope", a 2014 report from the Colorado Energy Office and Colorado Mesa University Water Center on produced water re-use along Colorado's Western Slope indicates a growing interest in finding alternative ways to treat and use produced water from oil and gas development.
Water management decisions can be aided by computer software. The Water Treatment Technology and Decision Tool provides a cost-effective tool that will allow operators to make fiscally and environmentally sound decisions on water management. It also promotes the identification of new sources of useable water for communities near unconventional gas resources by identifying potential end-uses for produced and flow-back water. The project website includes an overview of water treatment options, a catalog of treatments that characterizes and assesses existing and emerging technologies that are either being applied in shale gas arena, or have the capability for application, and regulatory information. The information provided is specific to the Barnett, Fayetteville, Haynesville, Marcellus, and Woodford shale plays, but provides information that would be generally applicable to other shale gas plays as well.
There are several processes employed to dispose of waste water from oil and gas development: evaporation, land application, surface water discharge, and injection. The process used depends on the regulatory regime, water quality, and developer practice. Injection is generally favored to dispose of brackish and otherwise contaminated waters unsuitable for surface water uses.
For a comprehensive analysis of current (2012) federal and state laws regulating oil and gas waste waters see the NRDC's In Fracking's Wake: New Rules are Needed to Protect Our Health and Environment from Contaminated Wastewater. The NDRC report finds that currently available storage, treatment, and disposal options are inadequate to fully protect human health and environment, but that stronger safeguards at state and federal levels could better protect against the risks associated with oil and gas wastewater.
Wastewater Injection -- Class II Injection Wells
The EPA Underground Injection Control (UIC) Program is responsible for regulating the construction, operation, permitting, and closure of injection wells that place fluids underground for storage or disposal in order to protect drinking water resources. Under this program, which is often delegated to the states for implementation, there are six classes of wells. Class II wells are used for injection of oil and gas related fluids. A small number of class II wells are used for storage of liquid hydrocarbons for the U.S. Strategic Petroleum Reserve. Most oil and gas related fluids are injected to enhance oil and gas development (secondary or tertiary recovery) or to dispose of waste fluids.
Based on an amendment to the Safe drinking Water Act added by the Energy Policy Act of 2005, however, the UIC Program does not regulate injection for hydraulic fracturing, unless diesel fuels are used in the fluids or propping agents. See the EPA webpage on Hydraulic Fracturing Under the Safe Drinking Water Act.
See the Induced Seismicity White Paper for an introduction to the issues.
One unintended consequence of wastewater injection is induced seismicity. While most earthquakes are naturally-occurring geologic phenomena, seismicity can be triggered by injection of fluids into the subsurface increasing the pore pressure in the rock that effectively reduces the natural friction on a fault. In Colorado, examples include induced seismicity from enhanced oil recovery in the Rangely Colorado oil field in the 1960-70s, brine disposal to control Colorado River salinity near Paradox, Colorado in the 1990s, and liquid waste disposal at the Rocky Mountain Arsenal in the 1960s. More recent earthquakes have been attributed to wastewater disposal wells in Greeley, Colorado and various other states including Oklahoma, Ohio, and Texas.
See the paper Regulating Our Way to Earthquake Free for legal and policy avenues to eliminate or minimize induced seismicity.
States are responding to both speculation and confirmation of wastewater injection induced seismicity with review and some revision of their regulations. For example, Colorado requires an operator to define, prior to permit approval, the seismicity potential and the proximity to faults through geologic and geophysical data if historical seismicity has been identified in the vicinity of a proposed wastewater injection well. The Texas Railroad Commission revised its wastewater injection regulations in August, 2014 to add various permit requirements and to clarify the authority of the agency to take action if a well is likely to be contributing to seismic activity. Oklahoma has responded with a “traffic light” system applied to both permitting decisions and active disposal wells. Oklahoma’s rules address various issues including permitting, monitoring, testing, and reporting requirements.
In addition to taking individual actions, states are also proactively discussing the possible association between earthquakes and injection of waste fluids with their peers. Under the auspices of the State Oil and Gas Regulatory Exchange of the States First initiative, states have initiated the Induced Seismicity by Injection Work Group.