How Underground Injection Control Helps Protect the Environment in New Mexico
Underground Injection - Why is it done?
Underground injection is important to New Mexico. By injecting millions of barrels of water into nearly 4,900 injection wells in depleted oil fields last year, over 13 million barrels of oil were recovered, most of which could never have otherwise been produced. This oil was worth nearly a billion dollars. The State received nearly 86 million dollars in direct taxes from this oil in additional to royalty income from the portion of the oil produced from state and federal lands.
It is estimated that another twenty-six million barrels of oil produced outside these water flood projects last year required the use of injection wells to dispose of the millions of barrels of mostly saline water produced with the oil. This oil was worth three quarters of a billion dollars and generated 64 million dollars in taxes.
Altogether, over 340 million barrels of water were injected in 1996 in approximately 350 water flood projects. Over 235 million barrels of water were injected in over 500 salt water (produced water) disposal wells during the year.
Underground Injection and the Environment - What is the hazard?
Ninety percent of New Mexicans' drinking water is derived from underground aquifers. If the fresh water in these aquifers becomes contaminated it is virtually impossible to restore its purity for drinking except at enormous and impractical cost.
Most of the water produced from well with oil and gas, as well as most of the water injected into water flood wells for purposes of oil recovery, is highly saline or otherwise undrinkable. The injection of these waters into deep wells below the fresh water aquifers is far safer than if it were disposed of on the surface where it could seep down into the fresh water and contaminate it. However, injection must be done safely to prevent the impure injected water from leaking from the wells or migrating upward from the injection zones into the fresh water. Individual and municipal water wells can be contaminated if either of these should occur.
The Underground Injection Control Program is intended to prevent fresh water contamination from injection activities in oil and gas production, in mining, and in industrial and municipal disposal operations.
Underground Injection Control - How is it done?
The New Mexico Oil Conservation Division (OCD) (a Division of the New Mexico Energy, Minerals and Natural Resources Department) has regulated underground practices in connection with oil and gas production since injection began in the state in 1952. Any individual or company wishing to begin an injection project must file a detailed application with the OCD stating all of the facts relating to the project. Except in a few limited cases, a public hearing is held on each such application.
The first requirement of safe injection is to be certain that the injection zone is below any drinking water source and that intervening layers of material in the earth will prevent the migration of injection fluids upward into the fresh zones. This is done by evaluating known geological information about the area of proposed injection. The operator of the proposed project presents evidence at the hearing to demonstrate that the injected fluids will not migrate out of the injection zone.
Another critical factor is the construction of the well. The proposed injection well(s) must be constructed with cement outside the well casing to seal off the fresh water zones. Cementing requirements vary from place to place depending on the geology and hydrology of the area and other factors. The application to inject includes a description of how the well(s) will be constructed.
If the Division approves the project, the operator submits an application to drill new injection wells, and/or convert producing wells, to the appropriate OCD District Office. District Field Inspectors inspect various phases of well construction. After a completed injection well has been successfully tested for mechanical integrity, the District office issues a permit to inject. An injection pressure limitation is specified for each well to prevent fracturing of the rock above the injection zone which could lead to fluid migrating into the fresh water aquifers above.
Periodically thereafter, the wells are inspected and tested under the supervision of District Field Inspectors to ensure that they have not developed leaks. Operators must report the volume and pressure of injected fluids monthly. When the well is no longer being used for injection, it must be safely plugged in a manner approved by the OCD District Supervisor. Most plugging of injection wells is witnessed by OCD inspectors.
If injected water is ever found in a zone other than the disposal zone, or if drinking water wells should become contaminated, extensive testing is done by the OCD and nearby well operators to determine the source of the problem. If an injection or other well is found to be leaking, the well is shut-in and necessary repairs promptly made. To date more than eight billion barrels of water have been injected in the oil reducing counties and the OCD has yet to find a single reported instance of contamination definitely traceable solely to an injection well. All injection wells in New Mexico's inventory are pressure tested every 5 years and inspected annually.
The eleven District Field Inspectors spend forty percent of more of their time inspecting injection and related wells and facilities. In 1996, inspectors spent 1,032 days inspecting. Of 1,200 tested and 3,000 routine inspections (3.1%) had defects and required repairs. Besides requiring well repairs, inspectors took more than 500 enforcement actions in the field with 38 of these being actual well failures.
The Underground Injection Control Program - How is EPA involved?
Protection of underground drinking water sources has concerned New Mexicans and has been growing as a national issue for a number of years. In the Safe Drinking Water Act of 1974, Congress empowered the U.S. Environmental Protection Agency (EPA) to establish a nationwide Underground Injection Control (UIC) Program. The federal UIC program is designed to enable state programs which meet federal standards to receive authority to continue to regulate injection practices within state boundaries. After final UIC regulations had been promulgated in 1980, New Mexico applied to the EPA and in 1982 EPA granted the state primary enforcement authority for underground injection wells in New Mexico related to oil and gas production. The New Mexico program was the second in the nation to be approved. The OCD is the operating agency for the program.
From January 1, 1979, when the first UIC grant to the state from EPA was received, through June 30, 1996, the state had received and spent over six million dollars in federal funds and an additional expenditure of nearly two million dollars in matching state funding on the UIC Program. The EPA exercises oversight for the program to be certain that federal regulations are being carried out and that the program is operating effectively.
Other Injection Wells - How are they regulated?
The vast majority of injection wells in the state are related to oil and gas production (more than 5,400). However, there are also additional types of injection wells in New Mexico. There were 165 in situ mining wells and 135 miscellaneous injection wells which had been identified by the end of 1996. The miscellaneous wells include geothermal injection wells, air conditioning and heat pump return flow wells, barrier wells, drainage, wells, mine backfill wells, mine water recirculation wells, industrial waste and waste disposal wells such as cesspools. Of these, the OCD regulates geothermal wells. The other types of injection wells are regulated by the New Mexico Environmental Department (NMED). The rules governing regulation of these wells are found in the Water Quality Regulations issued by the Water Quality Control Commission of which the NMED and the OCD are constituent agencies. (Oil and gas related injection wells are regulated under the OCD's Oil and Gas Rules and geothermal wells are regulated under the OCD's Geothermal Rules.) In July, 1983, the EPA granted New Mexico primary enforcement authority for the other cases of injection wells.
Since 1990, OCD has allocated a portion of the general UIC grant funds received from EPA to the NMED to carry out its regulatory responsibilities for the other classes of wells.
For more information on the Underground Injection Control Program, please contact:
David Catanach
Oil Conservation Division
1220 South St. Francis Dr.
Santa Fe, New Mexico 87505
Telephone: (505) 476-3466