Class II Injection Wells
The Preferred Way to Protect Water Sources, the Environment, and our Communities
UIC Injection Wells across the nation safely dispose of millions of gallons of brine obtained during oil and natural gas production. They return produced fluids brought to the earth’s surface during production back to where it came from. Safe disposal of the production brine from oil and gas production is crucial to environmental protection and energy production.
Why We Need Injection Wells
During oil and natural gas production brine is brought to the earth’s surface with oil or natural gas. Injection returns this saltwater back into the strata where it naturally occurs.
What Injection Wells Are
Injection Wells are drilled deep into the earth, and inject wastewater far below the freshwater aquifers and separated by confining geologic layers within the earth. Steel casing is run to the bottom of the hole. The casing is grouted in place with special cement. The casing isolates injection fluids from the well bore and from freshwater.
Drilling then continues below the casing down through the injection zone and casing is again cemented to the injection run. Injection fluids are pumped through another string of pipe called tubing. An injection packer is used near the bottom of the tubing to seal it against the casing. This packer prevents water from entering the space between the tubing and casing when water is injected. The pressure on the tubing annulus is continuously monitored to ensure there are no leaks.
Class II Injection Wells Protect Our Water Sources
Class II Injection Wells are:
Did You Know...
Disposal Injection Wells (Class IID) The second type of injection well is for disposal of fluids produced along with oil or gas. DEP promotes recycling as a first option when it is technically and economically feasible. However, some liquid waste must ultimately be disposed of and deep underground injection has been identified as one of the safest ways to manage such wastes. These produced fluids designated for disposal may be similar to freshwater in quality or water high in chloride and other dissolved solids. They include both flowback water and brine (deep water found naturally in geologic formations). Such wastes are a byproduct of oil and gas operations and are pumped back into the ground deep within the earth as a means of permanent disposal. In Pennsylvania, the rocks that can contain these fluids in pore spaces are typically depleted oil or gas reservoirs and are usually more than a mile below the earth’s surface. There is no discharge onto the land surface or into nearby surface waterways. Care also is taken to ensure that underground near surface sources of drinking water that are part of the hydrologic cycle are not affected when these fluids are pumped back into the ground. Several successful disposal wells are operating in Pennsylvania and options for more sites are always being considered. The history of underground disposal shows that it is a practical, safe and effective method for disposing of fluids from oil and gas production. Industry organizations like the American Petroleum Institute and interstate organizations like the Interstate Oil and Gas Compact Commission prefer injection wells to other means of wastewater disposal because the wastewater is returned to where it originated, thus eliminating the need to find an alternate disposal location. DEP also carefully regulates the surface operations at disposal well sites requiring that pollution, prevention, contingency and erosion and sediment control plans be developed prior to the commencement of disposal operations. (Source: Pennsylvania Department of Environmental Protection)