Drilling is simply the first step in the creation of a successful and productive natural gas well. For operations like those conducted by Chesapeake in the Marcellus Shale, hydraulic fracturing is an entirely different stage in the process, called completion. It comes after drilling and is a key reason why American natural gas stands poised to lead this region and our nation into a new era of energy independence.
The process has been used by the oil and gas industry since the 1940s and has become a key element of natural gas development worldwide. In fact, this process is used in nearly all natural gas wells drilled in the U.S. today. Properly conducted modern hydraulic fracturing is a safe, sophisticated, highly engineered and controlled procedure.
Hydraulic fracturing (a critical component of the completion process) only lasts three to five days per well. It is limited to a specific, environmentally safe area thousands of feet below freshwater zones. And it allows vast amounts of previously unattainable natural gas to flow efficiently and economically to the wellbore.
A carefully designed and controlled pressurized mixture of 99.5% sand and water – combined with 0.5% of special purpose additives – is pumped down a natural gas well and into the deep shale rock formation to create microfractures. These newly created microfractures are propped open by the sand, which allows natural gas to flow into and through the wellbore to be collected at the surface. The special-purpose additives are compounds found in common household products. They help reduce friction and corrosion and inhibit bacteria to make the fracturing process effective.
A representation showing the percent by volume composition of typical deep shale gas hydraulic fracture components (see graphic) reveals that more than 99% of the fracturing mixture is comprised of freshwater and sand. This mixture is injected into deep shale gas formations and is typically confined by many thousands of feet of rock layers.
Fracturing Ingredients
| Product Category |
Main Ingredient |
Purpose |
Other Common Uses |
| Water |
99.5%
water & sand |
Expand fracture and deliver sand |
Landscaping and manufacturing |
| Sand |
Allows the fractures to remain open so the gas can escape |
Drinking water filtration, play sand, concrete and brick mortar |
| Other |
approximately 0.5% |
| 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 produces corrosive by-products |
Disinfectant; Sterilizer for medical and dental equipment |
| Breaker |
Ammonium persulfate |
Allows a delayed break down of the gel |
Used in hair coloring, 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 |
| pH adjusting agent |
Sodium or potassium carbonate |
Maintains the effectiveness of other components, such as crosslinkers |
Used in laundry detergents, soap, water softener and dishwasher detergents |
| 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 |
|
Produced water returned to the wellbore during the completion process is collected and stored in holding tanks on-site. It is then pumped through a special filter and placed in a clean storage tank, tested and recycled. At the end of the fracing process, any remaining produced water is directed off-site to secure, designated, regulated locations.
Please note the amount of water used for all drilling and fracing operations in the Marcellus will represent less than a 1% increase of the total water usage in the region. Technological advancements in horizontal drilling and hydraulic fracing are precisely why American natural gas is in the midst of a true productivity revolution. And it stands to benefit those living in the Marcellus Shale region in many ways – while giving our nation the resources to achieve true energy independence and a clean energy future.
Once completed, storage tanks and other production equipment are installed and the wellsites are fenced for security. In many cases, the company makes additional improvements to the area surrounding the wellsite. Because of these improvements, completed wellsites are frequently more appealing than other utilitarian structures, such as water pump houses or electrical stations.