Q. What chemicals are used in natural gas production?
A. Chemicals used in natural gas production include:
Friction reducer — a lubricant that allows the fluid to carry frac sand into the formation
Corrosion inhibitor — protects the metal casing against corrosion
Bactericide — prevents commonly occurring biological materials from beginning natural decomposition
Anti-freeze agent — used seasonally to prevent ice from forming
For a more extensive list of the chemicals used in natural gas production, click here.
Used at low concentrations, these chemicals are no more toxic than many household items used daily by consumers.
Q. How are fluid leaks prevented during natural gas drilling?
A. A number of redundant safety measures are in place to prevent leaks. All fluids used in the natural gas drilling process are contained in a closed-loop system, which involves using a series of steel bins.
The design of the site also works to ensure that all liquid run-off is contained. At each site, a system of small diversion channels empty into a collection area, which is monitored and pumped out as the level rises.
Not only are any potential spills contained, but rain water run-off is also collected on location and then hauled offsite to make certain that nothing from the location impacts the surrounding environment.
Q. What precautions are taken to prevent produced water spills at the natural gas drilling site?
A. Once separated from the gas, the produced water is moved into on-site tank batteries. A metal barrier, which supports an interior liner that is impervious to leaks, surrounds the tank battery area at each natural gas wellsite, preventing the escape of produced water into the ground.
Q. What is the likelihood of a natural gas leak at the wellhead during the drilling process?
A. Until the well is completed, free-flowing natural gas is rarely encountered in the Barnett Shale because of its tight rock formation. Still, precautions are taken to prevent natural gas leaks from occurring.
Specialized equipment, such as a blow-out preventer, is installed on every well and continually monitors pressure levels during the drilling process. An automatic alarm can sound if the pressure becomes too high or too low.
Q. What safety measures are in place to protect residents living near wellsites in the Barnett Shale region?
A. Since the natural gas is not flowing during drilling, the odds of an offsite incident are slim to none.
Once a well is completed, pressure release valves are built into these systems to allow for the safe and controlled release of pressure, when needed, virtually eliminating possibility of an incident.
Because natural gas is lighter than air, any released gas rises into the atmosphere and quickly dissipates, posing no harm to surrounding residents. It is only when a gas leak is confined within a structure where it cannot escape, such as a house, that there is a cause for concern.
Three things — fuel, oxygen and an ignition source — are necessary for combustion to occur. Operators strive to eliminate ignition sources at natural gas wellsites by using appropriate combustion-proof electronic equipment and lightning arrestors.
In the Barnett Shale and throughout Texas, there have been no reported resident or bystander injuries as a result of a natural gas wellsite incident.
Q. What is a blowout and what practices are used to prevent or remedy such an incident?
A. A blowout is the term associated with an unplanned release of oil, natural gas or mud flow from a well. Precautions are taken to prevent and to safely and expeditiously address any incident which could occur from a blowout.
All Chesapeake Energy wellsites are equipped with blowout preventers, or BOPs. A BOP is a large valve located on the top of a well that can be closed immediately if a change of pressure warrants it. BOPs are critically important to the safety of the crew and are inspected, tested and refurbished at regular intervals.
In addition to BOPs, each rig is equipped with a pit volume totalizer, also known as a pit-level indicator, which continuously monitors the level of the drilling mud in the mud tanks. If the mud level drops too low or rises too high, the alarm sounds to warn the driller of a loss of circulation or a kick, which is a flow of reservoir fluids into the wellbore during natural gas drilling operations.
All supervisory level personnel on location are required to be certified in well control every two years.
Q. How will Chesapeake Energy work with local authorities to manage an emergency situation in the Barnett Shale?
A. Chesapeake Energy will work closely with local authorities to resolve any potential emergency situations involving natural gas production.
Chesapeake Energy first responders are trained to:
Control the source to extinguish extinguish gas fires, if any
Work at the natural gas well/rig site
Mitigate leaks by closing valves
Contain spills, preventing run-off to bodies of water
Work closely with local authorities to resolve the situation.
Local authorities will:
Provide fire suppression as appropriate
Protect population
Protect collateral assets
Coordinate with the operator
Use LEL meters to determine areas of concern
Q. What emergency response plan is in place should an incident occur?
A. The risk of any problem beyond the actual padsite is extremely low. If an incident should occur, the natural gas industry works in close conjunction with the appropriate emergency response teams, just as any other industry is required to do in the case of an emergency.
The City of Fort Worth has a comprehensive plan to respond to any emergency situation. According to information from the city’s website (www.fortworthgov.org), as emergency personnel arrive on-scene, the proper response actions are determined and provided to the public. The actions are based on the situation and variables at the time. During non-emergency times, first responders develop possible scenarios and practice their response to ensure effectiveness and efficiency during an actual event.
The recommended actions may be disseminated to the public by:
Sounding the outdoor warning system
Local television and/or radio stations
The NOAA all-hazard radio
Emergency personnel door-to-door notification in the affected area
Q. Do natural gas wellsites have an on-site fire suppression system, and if so, what does it entail?
A. As a precautionary measure, a foam line is installed outside the perimeter of the natural gas wellsite to aid firefighters in the event of an emergency. This line allows them to connect a hose that will pump foam into production equipment that will extinguish any problem without having to enter the site.
Q. Where can I access incident reports and statistics for natural gas drilling and production?
A. The Railroad Commission of Texas (RRC) regulates oil and gas production within the state, as well as, establishes and enforces safety procedures for the industry. As required by state law, all incidents are required to be reported to the commission, as information of public record. The RRC website is www.rrc.state.tx.us.
Q. What is H2S?
A. H2S is a naturally occurring gas primarily from the biological decomposition of older oil and gas fields, such as the Permian Basin area. As the field depletes its supply of oil, more decomposition occurs and concentrations of H2S increase. That is why a bactericide is added to natural gas wells, simliar to using Formula 409 on kitchen countertops in your home to kill bacteria.
Q. What is coalbed methane?
A. Coalbed methane (CBM) is a naturally occurring gas found in coal formations that exist at depths of a few hundred feet to a few thousand feet beneath the surface, and is not generally found in the Barnett Shale.
Q. How is CBM different from the natural gas found in the Barnett Shale?
A. CBM formations are often associated with drinking water resources because they generally occur at depths shallower than traditional natural gas reservoirs and are sometimes found in close proximity to freshwater aquifers. In contrast, the Barnett Shale formation is found more than a mile below the surface. This means that more than a mile of impermeable rock separates drinking water aquifers from the zones at which natural gas production is occurring, thus providing a natural barrier of protection for the water table.
Q. What is a sinkhole and how do they occur?
A. Sinkholes or cave-like structures can occur in other areas of the state and country where a certain type of rock or salt dome exists, which can dissolve over time by contact with water. Once a formation begins eroding, a sinkhole or cave may be created. Some natural geological wonders which may be familiar to the public include the Natural Bridge Caverns in South Texas and Carlsbad Caverns in New Mexico. The Texas Speleological Survey, a non-profit corporation established in 1961 to collect, organize, and maintain information on Texas caves, says there are no known sinkholes or caves located in Tarrant County.
Q. Does drilling for natural gas create a cave or void?
A. No, people sometimes assume that when natural gas is extracted from below the surface, an empty space is created and this space will eventually cave-in. This way of thinking is inaccurate and does not apply to natural gas production in the Barnett Shale for several reasons. First, the shale or tight rock remains in place after the hydraulic fracture stimulation process. therefore, there is no weakness created when gas is extracted. The 1.5 miles of impermeable rock that exists between the surface and the Barnett Shale makes it virtually impossible for a sinkhole to form in this region. Secondly, the rock or tight shale that operator are working in does not dissolve, regardless of any contact with water. The shale is merely cracked during hydraulic fracturing, which allows gas to be released while the rock remains in place miles below the surface.
Resources
Click on the links below to read the Texas Commission on Environmental Quality's
(TCEQ) report entitled "Analysis of Emissions from Natural Gas Production in the Barnett Shale."
TCEQ Executive Summary
TCEQ Official Report