Hydraulic Fracturing

Hydraulic fracturing, commonly referred to as fracing, is the process of creating small cracks, or fractures, in underground geological formations to allow natural gas to flow into the wellbore and on to the surface where the gas is collected and prepared for sale to a wide variety of consumers.  Variables such as the permeability and porosity of the surrounding rock formations and thickness of the targeted shale formation are studied by geoscientists before the fracing process is conducted. The result is a highly sophisticated and carefully engineered process that creates a network of fractures that are safely contained within the boundaries of the targeted deep shale natural gas formation.

During the fracing process, a mixture of water, sand and other chemical additives designed to protect the integrity of the geological formation and enhance production is pumped under high pressure into the shale formation to create small fractures. The mixture is approximately 99.5% water and sand, along with a very small amount of special-purpose additives. The newly created fractures are “propped” open by the sand, which allows the natural gas to flow into the wellbore where it is collected at the surface and subsequently delivered to a wide ranging group of consumers.

Natural gas has been formed over tens of millions of years from the deposits of organic matter that have been buried by thousands of feet of sedimentation from erosion. When natural gas is formed, it slowly migrates through pores in the source rocks (usually organic-rich shale and sometimes limestone) to create natural gas reservoirs. These reservoirs are created when the gas becomes “trapped” by the existence of a nonporous, impermeable rock layer above the porous layer. This barrier prevents further upward migration and these reservoirs become the targets for drilling operations. It is these accumulated deposits that form the collection of natural gas reserves that comprise the massive unconventional shale reserves that have vastly increased the domestic deposits of clean-burning natural gas.

Without the recent and significant technological advancements made in horizontal drilling and in hydraulic fracturing, the natural gas found in deep shale formations would be, uneconomic and unrecoverable. The creation of small cracks, or fractures, in the shale allows the natural gas trapped within the very dense rock formation to flow through the wellbore so that it can be collected at the surface.

Approximately 99.5% of the volume of materials used during the fracing of deep shale gas wells consists of water and sand. Other typical ingredients include a friction reducer, gelling agent and antibacterial agents. A typical deep shale fracturing mixture and a list of typical additives are provided below:

Fracing chemicals are no more dangerous than any industrial or household chemicals when used properly. However, they do require safe work practices, proper site preparation and attentive handling to ensure the safe management of chemicals, as well as the protection of the public, wellsite employees, contractors and the environment. Each chemical used during the fracing process has a Material Safety Data Sheet (MSDS), which is readily available at a central location for all personnel on the job site. The MSDS outlines the hazards associated with wellsite chemicals and the appropriate steps to protect the user and the environment. It is important to note that in deep natural gas shale drilling operations the targeted fracing zones are, on average, located an estimated 6,000 to 12,000 feet below the freshwater zones, and are separated by millions of tons of impermeable and nonporous rock formations thus making the potential for migration into freshwater zones a near scientific impossibility.

Agencies confirm that operators are complying with regulations through a number of established methods. Several methods include permits, completion reports and inspections. These methods are more fully described below.

When is a permit acquired?

Regulatory agencies require permits before construction. A detailed review of permit applications is conducted by the agencies to verify that project designs meet regulatory requirements before work is performed on the targeted location. Once the well project design is approved, a permit, with specific operating instructions, is provided to the operator. Depending upon the targeted location, additional permits may be required.

What type of agency reporting is required?

The operator is required to submit completion reports to the proper state agency to provide information on the final freshwater casing protection design program for each well. This information includes the size and amount of casing to be used in the well, in addition to the amount of cement used to seal off the casing from the surrounding earth. The location where the fracing will occur and the type of stimulation materials (hydraulic fracturing) are also detailed on the report. Any additional operational equipment installed in the wellbore will also be noted on the report.

When are inspections conducted?

Agencies can, and do, conduct inspections during or after drilling, construction and production to verify that all project work performed by the operator is in compliance with the proper regulations and permits.

Each state implements specific programs to protect its underground drinking water resources. Steel casing with  surrounding layers of concrete are installed to isolate the well and protect  the drinking water aquifers through which the wellbore penetrates. The depth at which the surface casing extends below these freshwater aquifers is mandated by each state’s regulatory agency. Typically surface casing is set to a depth of more than 50 to 100 feet below the base of the freshwater aquifer to seal it off from any possible migration of external fluids.

Chesapeake’s cementing and casing programs are designed and implemented to comply with these regulations and generally exceeds them. A specialized well survey (cement bond log) is also used to verify the integrity of the cementing program.

After it is determined that the well is capable of producing  natural gas, a tubing string is set to provide an added layer of separation between the natural gas stream and freshwater aquifer. The multiple layers of steel and cement which go into the construction of a natural gas well, when properly installed, virtually eliminate the possibility of contamination to these freshwater zones.

Spills at the wellhead during fracing activities are extremely rare. The piping and fracing equipment used to transport fluids to the wellhead are inspected and pressure tested prior to the start of each fracture treatment. The equipment is pressure rated and continuous monitoring occurs during operations to ensure that pressures remain below the safety-rated pressure levels. Raw chemicals are maintained inside lined secondary containment areas to catch any releases before they can migrate off the site. Likewise, the sites are specifically constructed to contain any releases to the wellsite.
 
In addition, preventative maintenance is used to ensure that equipment is functioning properly and performing its intended function. Chesapeake employees and their vendor partners receive training before, during and after fracing is completed to foster continuous learning and improvements to the process.

Chesapeake and its partners actively use a number of BMPs on the wellsite during fracing operations to prevent fluid spills and run-offs. As previously described, primary preventative measures involve routine pressure testing and maintenance of fracing equipment prior to commencing operations, proper handling and temporary storage of materials and employee training on spill prevention practices. Based on lessons learned during the course of our operations, Chesapeake has implemented additional BMPs to further mitigate the potential for spills and negative impacts to the environment. Some of these BMPs include:

• Sites designed and constructed to minimize storm water run-off, which prevent fluids from flowing off the location.
• Department of Transportation approved chemical containers are maintained inside lined secondary containment areas to catch potential leaks.
• Secondary containment and diversion systems are used at hose and pipe connections to catch and contain potential leaks.
• Structured processes are implemented for the transfer of chemicals to provide the safest approach possible for employees, contractors and the environment.