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 natural gas and oil 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) lasts from approximately a few days to no more than a couple of weeks, depending on the number of required stages and the number of wells being completed at the wellsite. 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 approximately 99% sand and water – combined with approximately 1% 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 |
Purpose |
Downhole Result |
Other Common Uses* |
|---|
| Water and Sand: approximately 99% |
| Water |
Expand fracture and deliver sand |
Some stays in formation while remainder returns with natural formation water as "produced water" (actual amounts returned vary from well to well) |
Landscaping, manufacturing |
Sand
(Proppant) |
Allows the fractures to remain open so the gas can escape |
Stays in formation, embedded in fractures (used to "prop" fractures open) |
Drinking water filtration, play sand, concrete and brick mortar |
| Other Additives: approximately 1% |
| Acid |
Helps dissolve minerals and initiate cracks in the rock |
Reacts with minerals present in the formation to create salts, water, and carbon dioxide (neutralized) |
Swimming pool
chemical and cleaner |
| Anti-bacterial Agent |
Eliminates bacteria in the water that produces corrosive byproducts |
Reacts with micro-organisms that may be present in the treatment fluid and formation. These micro-organisms break down the product with a small amount of the product returning in produced water. |
Disinfectant; sterilizer for medical and dental equipment |
| Breaker |
Allows a delayed breakdown of the gel |
Reacts with the "crosslinker" and "gel" once in the formation making it easier for the fluid to flow to the borehole. Reaction produces ammonia and sulfate salts, which are returned in produced water. |
Used in hair coloring, as a disinfectant, and in the manufacture of common household plastics |
| Corrosion inhibitor |
Prevents corrosion of the pipe |
Bonds to metal surfaces (pipe) downhole. Any remaining product not bonded is broken down by micro-organisms and consumed or returned in produced water. |
Used in pharmaceuticals, acrylic fibers and plastics |
| Friction reducer |
“Slicks” the water to minimize friction |
Remains in the formation where temperature and exposure to the "breaker" allows it to be broken down and consumed by naturally occurring micro-organisms. A small amount returns with produced water. |
Used in cosmetics including hair, make-up, nail and skin products |
| Gelling agent |
Thickens the water in order to suspend the sand |
Combines with the "breaker" in the formation thus making it much easier for the fluid to flow to the borehole and return in produced water. |
Cosmetics, baked goods, ice cream, toothpaste, sauces, and salad dressings |
| Iron control |
Prevents precipitation of metal (in pipe) |
Reacts with minerals in the formation to create simple salts, carbon dioxide and water all of which are returned in produced water |
Food additive; food and beverages; lemon juice |
| Scale inhibitor |
Prevents scale deposits downhole and in surface equipment |
Product attaches to the formation downhole. The majority of product returns with produced water while remaining reacts with microorganisms that break down and consume the product. |
Used in household cleansers, deicer, paints, and caulk |
| Surfactant |
Used to increase the viscosity of the fracture fluid |
Generally returned with produced water, but in some formations may enter the gas stream and return in the produced natural gas |
Used in glass cleaner, multi-surface cleansers, antiperspirant, deodorants and hair-color |
| |
*Other common uses of the product may not be in the same quantity or concentration.
To alleviate concerns about chemical constituents, Chesapeake supports and is actively participating in the public disclosure of fracing ingredients used in our operations. Chesapeake voluntarily discloses our frac fluids through the Ground Water Protection Council/Interstate Oil and Gas Compact Commission’s disclosure website, www.fracfocus.org. In addition, where required by law, we report these ingredients to all of the appropriate state agencies.
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 disposal facilities.
Please note the amount of water used for all drilling and fracing operations in the Marcellus will represent less than a 0.1% 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 the well is completed, storage tanks and other production equipment are installed; fences may be added around the wellsite or equipment. 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.
Green Frac®
Chesapeake’s Green Frac® program was founded in October 2009 to evaluate the types of additives typically used in the process of hydraulic fracturing and to determine their environmental friendliness. After evaluations are completed, Green Frac calls for the elimination of any additive not critical to the successful completion of the well and determines if greener alternatives are available for all essential additives.
An industry-leading program, Green Frac is a decisive move toward an even greener fluid system. By reviewing all of the ingredients used in each frac, the program identifies chemicals that can be removed and tests alternatives for remaining additives. To date, the company has eliminated 25% of the additives used in frac fluids in most of its shale plays.
Learn more about Chesapeake’s Green Frac program.