AskChesapeake

What chemicals are used during natural gas production?

Different chemicals are used during drilling, well completion and production. For drilling and production, the need for chemical uses is driven by a variety of site specific factors, including the chemical and physical properties of the underlying geology and gas reservoir.

Drilling

Drilling activities use water and drilling mud to circulate cuttings (rock chips created as the drillbit grinds through the rock) to the surface to clear the borehole. The drilling fluids lubricate and cool the drillbit, stabilize the wellbore to prevent it from caving in, and control fluid pressure in the well. Drilling mud can be either water-based or oil-based. Additives are also used in drilling fluids to help control the drilling process. Water-based drilling fluids may contain the following additives:

• Gels that help the drilling fluid carry cuttings
• Soda ash or lime for pH control
• Polymers that prevent water from reacting with or seeping into the shale formation
• A weighting agent, such as barite

Additives for oil-based drilling fluids may include:

• Emulsifiers that keep the diesel-based liquid and water in the drilling fluids from separating
• Viscosifiers that help drilling fluids carry cuttings
• A weighting agent, such as barite

Completion

Completing a well involves hydraulic fracturing, commonly referred to as fracing, which is essential for the production of natural gas from shale formations. Fracing is the process of creating fissures, or fractures, in underground formations to allow natural gas to flow up into the wellbore. In Chesapeake’s deep shale gas plays, water, sand and other additives are pumped under a high pressure into the formation to create fractures. This fluid is over 99% water and sand, along with a small amount of special-purpose additives. Additives are used in fracing fluids to allow fracing to be performed in a safe and effective manner. Additives used in fracing fluids include a number of compounds found in common consumer products and are identified in the following table.

Fracturing Fluid Additives, Main Compounds and Common Uses

Additive Type	Main Compound	Purpose	Common Use of Main Compound
Acid	Hydrochloric acid or muriatic acid	Helps dissolve minerals and initiate cracks in the rock	Swimming pool chemical and cleaner
Antibacterial agent	Glutaraldehyde	Eliminates bacteria in the water that produce corrosive by-products	Disinfectant; Sterilizer for medical and dental equipment
Breaker	Ammonium persulfate	Allows a delayed break down of the gel	Used in haircoloring, as a disinfectant, and in the manufacture of common household plastics
Corrosion inhibitor	n,n-dimethyl formamide	Prevents the corrosion of the pipe	Used in pharmaceuticals, acrylic fibers and plastics
Crosslinker	Borate salts	Maintains fluid viscosity as temperature increases	Used in laundry detergents, hand soaps and cosmetics
Friction reducer	Petroleum distillate	“Slicks” the water to minimize friction	Used in cosmetics including hair, make-up, nail and skin products
Gel	Guar gum or hydroxyethyl cellulose	Thickens the water in order to suspend the sand	Thickener used in cosmetics, baked goods, ice cream, toothpaste, sauces, and salad dressings
Iron control	Citric acid	Prevents precipitation of metal oxides	Food additive; food and beverages; lemon juice ~7% citric acid
Clay stabilizer	Potassium chloride	Creates a brine carrier fluid	Used in low-sodium table salt substitute, medicines and IV fluids
Oxygen scavenger	Ammonium bisulfite	Removes oxygen from the water to protect the pipe from corrosion	Used in cosmetics, food and beverage processing and water treatment
pH adjusting agent	Sodium or potassium carbonate	Maintains the effectiveness of other components, such as crosslinkers	Used in laundry detergents, soap, water softener and dish washer detergents
Proppant	Silica, quartz sand	Allows the fractures to remain open so the gas can escape	Drinking water filtration, play sand, concrete and brick mortar
Scale inhibitor	Ethylene glycol	Prevents scale deposits in the pipe	Used in household cleansers, de-icer, paints and caulk
Surfactant	Isopropanol	Used to increase the viscosity of the fracture fluid	Used in glass cleaner, multi-surface cleansers, antiperspirant, deodorants and hair color

Production

During the production phase the most common types of chemicals used are scale/corrosion inhibitors, foamers and soaps (for low volume wells), dehydrating agents, hydrogen sulfide scavengers and agents to prevent freezing. Again, the need for these types of chemicals vary based upon site specific conditions.

How are fluid leaks prevented during drilling?

A number of overlapping safety measures are in place to prevent leaks. At each site, a system of small diversion channels empty into a collection area, which is monitored and pumped out as the level rises. This site design also works to ensure that all liquid run-offs are contained; minimizing the risk of any potential leaks or spills leaving the site.

What precautions are taken to prevent produced water spills at the site?

Once separated from the gas, the produced water is moved into tank batteries at the site through a closed piping system. The produced water is stored in aboveground tanks until water trucks remove and transport it to the disposal location.

What is the likelihood of a gas leak at the wellhead during the drilling process?

Until the well is completed, free-flowing gas is rarely encountered in the Marcellus Shale because of its tight rock formation. Still, precautions are taken to prevent gas leaks from occurring. Specialized equipment, such as a blowout preventer (BOP), 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.

What safety measures are in place to protect residents living near wellsites?

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 the 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 the wellsite by using appropriate combustion-proof electronic equipment and lightning arrestors.

What is a blowout and what practices are used to prevent or remedy such incident?

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 result from a blowout.

All wellsites are equipped with BOPs during the drilling phase. A BOP is a large valve at the top of a well that can be closed immediately if warranted by a change in pressure. 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 drilling operations.

Chesapeake trains all supervisory level personnel on location, and requires recertification in well control every two years.

How will Chesapeake work with local authorities to ensure emergency situations are handled appropriately?

Chesapeake promotes public safety, environmental protection and public understanding of our operations in the communities where we operate. Chesapeake values these communities and takes the responsibility of operating in a socially responsible manner very seriously. Our efforts to accomplish this include, but are not limited to:

• Maintaining an Emergency Response Plan (ERP)
• Submitting chemical information to local responders, local emergency planning committees and the states where we operate
• Providing training to local emergency responders on our ERP
• Conducting environmental and safety training to provide safe and environmentally responsible working operations for employees and the public
• Establishing partnerships with professional, experienced emergency response contractors
• Conducting regularly scheduled meetings with our contractors to discuss environmental, health and safety issues, including ERP
• Conducting emergency response drills with employees, contractors and local responders to ensure the effectiveness of the ERP
• Using signs and labels to identify our drilling locations and production sites
• Posting 24-hour emergency contact information on our signage located at the entries to our locations and sites
• Posting hazard identification at the gates to and on our locations

What emergency response plan is in place should an incident occur?

Although rare, situations can occur which require an immediate, organized and focused response by Chesapeake. To prepare for and respond to these situations on our locations, Chesapeake has developed a single, comprehensive approach to emergency management. The objective of our emergency response efforts is to ensure that all levels of the company have the capability to work together efficiently and effectively. To achieve this objective, we employ the same emergency response structure used by first responders, the Incident Command System. By working as a team with emergency response contractors and local first responders, such as the fire department, we are able to respond quickly and efficiently with one main objective: protect the public, our employees and the environment.

In the event of an emergency, an immediate and organized response by Chesapeake will be activated. Our ERP establishes the framework and response guidelines for designated Chesapeake employees based on the type and nature of the incident. The ERP outlines procedures for handling emergencies to minimize adverse impacts on  the public, our employees and the communities where we operate. The first priority during an emergency is the safety of the responders and the public involved, followed by the environment and property. All levels of the Chesapeake organization work together to plan and prepare for emergencies.

Where can I access incident reports and statistics for natural gas drilling and production?

The Pennsylvania Department of Environmental Protection (DEP) regulates oil and natural 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 DEP, as information of public record.

Flaring

What is flaring?

A flare is the result of a controlled burn of natural gas from a well. This is a safe way to test a well’s performance. Although some residents of Pennsylvania may be unfamiliar with this process, flaring is a common practice within the oil and natural gas industry, as well as a number of other industries. Garbage dumps and landfills often flare in order to control the methane gas naturally produced by the decomposition of organic materials.

Does Chesapeake flare?

Chesapeake flares on a case-by-case basis. Flaring is usually conducted to test the well’s production and determine the need for a pipeline when one does not yet exist.

How is flaring done?

The flaring process involves directing gas into a vertical pipe and lighting it. This controlled flame rises from the stack and is never large enough to extend beyond the perimeter of the site. Because only gas is burned during this process, no sparks or embers are generated to cause a fire concern in the surrounding area.

Why is flaring done?

Through the use of flaring, Chesapeake is able to more effectively assess a well’s production capabilities and determine areas where pipelines are most needed to begin transporting the gas to market, and eventually on to homes, schools, offices and factories. In urban areas, building natural gas pipelines often involve numerous tracts of land and extensive negotiations of right-of-way easements for the development of a proposed pipeline route. To avoid constructing unnecessary pipelines, a well may be flare-tested to judge the quality and quantity of its production. Depending on the results, a decision is made on whether or not to build the pipeline.

Is flaring safe?

Before a well is flared, Chesapeake extends notification to the DEP Oil and Gas inspector and local response authorities as a courtesy. The process is closely monitored in accordance with DEP regulations, and a supervisor is on-site 24 hours a day during the short period of time the flaring takes place, usually a few days.