A Look Below the Surface

Natural Gas Development & Disposal WellsSafeguards in Regulations and TechnologyDuring the initial phase of a well’s natural gas production, saltwater and hydraulic fracturing fluid are produced and brought to the surface through the wellbore. Though the U.S. Environmental Protection Agency (EPA) has determined this fluid is non-hazardous, the agency mandates it must be disposed of in a safe and responsible way to protect public health and safety. Disposal wells are drilled solely for this purpose, and are generally over one mile deep, considerably below fresh drinking water wells, which are usually no deeper than a few hundred feet. The Texas Railroad Commission (RRC), under national guidelines and the federal Safe Drinking Water Act, has ensured the safety of our state’s 50,000+ disposal wells for more than 30 years.

Groundwater SafetyProtection of underground aquifers is paramount, and multiple protection mechanisms are employed to safeguard water supplies at all stages of development. Disposal wells are drilled through layers of impermeable rock and constructed with three layers of steel and concrete casing to protect groundwater, all three of which would have to fail simultaneously to affect groundwater:1. Protection 1: Surface casing is a steel pipe

encased in cement reaching from the surface to below the freshwater aquifer. The Texas Commission on Environmental Quality (TCEQ) determines the exact, and most protective, depth of this casing layer.

2. Protection 2: String casing is a steel pipe placed in the wellbore all the way to the well’s total depth and

cemented into place. 3. Protection 3: Injection tubing and a “packer” are

placed last to inject the water.Annual inspections are mandatory and, according to RRC data, there are no known instances of groundwater contamination as a result of disposal activities.

Regulatory OversightThe RRC regulates the disposal of fluids produced by natural gas and oil development through the EPA’s Underground Injection Control program, which sets the standards for disposal well placement, permitting and construction, and maintenance and monitoring of every well to ensure fresh water sources are safeguarded. All Texas injection wells also are thoroughly investigated and vetted by the RRC, which examines every aspect of development, from geological formations to water table integrity. Once a proposed site is identified, the RRC requires a multi-step application process, public hearings and a

Multiple protection mechanisms safeguard water supplies, including three layers of steel and

concrete.

technical review process. Well placement must meet criteria for site location, property rights, and a geological study must ensure there is a proper injection zone. The RRC also requires developers to give public notice of their application.

Disposal well application requirements under Texas law include:

Well logs indicating the top and bottom of the proposed injection zone and overlying rock formationsGroundwater depth letter from the Groundwater Advisory Unit stating the well will not endanger usable quality groundwater.Maps showing the location of all wells within a ½-mile radiusTable illustrating all wells within a ¼-mile radius that will intersect the injection zoneAffidavit indicating the application has been published in a general-circulation newspaper

o Published notifications must contain instructions for individuals who wish to protest the application

o Publications must include the phrase “Application for Commercial Oil and Gas Waste Disposal Well”

Permits are limited to the injection of produced saltwater unless the application specifically lists other fluids to be injected.

Commitment to ConservationA large part of the natural gas community’s commitment to responsible environmental stewardship revolves around the ability to be conscious of community water needs and to continually advance the ability to “reduce, reuse and recycle.” Companies are aggressively exploring and adopting reuse technologies at the well site, which are helping to minimize the number of disposal wells needed. A few examples of these efforts include:

Where applicable, technologies such as hybrid-stimulation techniques are employed, which use a combination of gels and water and can cut water use by 40 percent. Where it is feasible with local geologies, companies take advantage of seasonal precipitation, and use non-potable water, like municipal wastewater, that does not compete with community needs for freshwater. The natural gas community is continually exploring new technologies that increase conservation, efficiency and recycling.Many companies also are looking to on-site water treatment and recycling technologies, which allow them to treat and reuse water at the drilling site, eliminating the need for outgoing trucks to haul wastewater and reducing the need for fresh water supplies.

In Texas, these efforts have been very successful, and the focus on innovation is ongoing. In South Texas alone, according to the RRC, companies have reduced the volume of water used in shale development overall by a third.

Security at the SurfaceRegulations also mandate all storage and surface facilities must be constructed of steel, concrete or fiberglass, and all surface facilities must be manned by an attendant 24 hours a day or fenced and secured by locked gate or keypad.

Seismic ConsiderationsThe RRC and industry have taken additional steps to mitigate disposal well-related seismic activity. These added safeguards include limiting well-pressure thresholds, assessing seismic susceptibility, and

Find out more about natural gas at www.ANGA.us.Natural Gas. Smarter Power Today.

monitoring seismic activity at well sites. The natural gas community also takes great care to ensure its activities are conducted away from fault lines and other seismically sensitive regions.

“[W]astewater disposal wells have been operating safely and without incident in the U.S. for many decades.”

– Mark Zoback, Professor of Geophysics, Stanford University

Compiled from Texas Railroad Commission - http://www.rrc.state.tx.us/forms/publications/HTML/pmt-outl.php

Find out more about natural gas at www.ANGA.us.Natural Gas. Smarter Power Today.