Drilling is simply the first step in the creation of a successful and productive well. For operations like those conducted by Chesapeake in the Niobrara Shale, hydraulic fracturing is an entirely different stage in the process, called completion. It comes after drilling and is necessary to release the oil and natural gas trapped in the rock so it can flow to the surface.
The process, commonly referred to as fracing, has been used by the oil and natural gas industry since the 1940s and has become a key element of shale development worldwide. In fact, this process is used in nearly all shale wells drilled in the U.S. today. Properly conducted modern fracing is a safe, sophisticated, highly engineered and controlled procedure.
Fracing (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. It allows vast amounts of previously unattainable oil and natural gas to flow efficiently and economically to the wellbore.
A carefully designed and controlled pressurized mixture of sand and water – combined with special-purpose additives – is pumped down a oil or 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 oil and 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 approximately 98% of the fracturing mixture is comprised of freshwater and sand. This mixture is injected into deep shale 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 98% |
| 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 2% |
| 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 |
| Clay stabilizer |
Prevents formation clays from swelling |
Reacts with clays in the formation through a sodium-potassium ion exchange. Reaction results in sodium chloride (table salt), which is returned in produced water. |
Used in low-sodium table salt substitute, medicines, and IV fluids |
| 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 |
| Crosslinker |
Maintains fluid viscosity as temperature increases |
Combines with the "breaker" in the formation to create salts that are returned in produced water. |
Used in laundry detergents, hand soaps and cosmetics |
| 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 |
| pH Adjusting Agent |
Maintains the effectiveness of other components, such as crosslinkers |
Reacts with acidic agents in the treatment fluid to maintain a neutral (non-acidic, non-alkaline) pH. Reaction results in mineral salts, water and carbon dioxide; a portion of each is returned in produced water. |
Used in laundry detergents, soap, water softener and dish washer detergents |
| 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.
Technological advancements in horizontal drilling and fracing are precisely why oil and natural gas production stands to benefit those living in the Niobrara Shale region in many ways – while giving our nation the resources to achieve true energy independence and a clean energy future.
Green Frac®
Chesapeake’s Green Frac® program founded in October 2009 to evaluate the types of additives typically used in the process of fracing 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.