A well can be hydraulically fractured multiple times to re-stimulate the flow of oil or gas. Once the operator determines the well to be past production or unsuccessful, it is shut down. The state regulates the well abandonment process, often mandating the materials used to plug the well and their placement. Depending on the state, the regulatory agency might also send staff to witness the plugging of the well. In addition to proper well abandonment at the end of the production phase, ongoing inspection and maintenance is required.
Plugging the well involves permanently sealing it with cement and other materials to prevent fluid migration to aquifers, surface water, and surface soils. 1 To maintain integrity, multiple plugs are placed in the wellbore, along with fluids at specific pressures in certain well depths. The operator conducts tests to ensure stability. The steel casing of the wellbore is cut off below the surface and capped with a steel plate. The company removes any remaining equipment from the site, reducing the footprint down to the wellhead. The company then usually works with the surface owner – and is often required to by state law – to restore the land, soil, and vegetation as specified in the surface use agreement (or according to regulatory requirements on state and federal lands). According to the API community engagement guidelines, “Communities can expect the land to be reclaimed or restored as close as possible to its original or current surrounding state.” 2 The operator may also install a marker on the site that indicates the well location, well number, and operator to facilitate site identification in the future. 3
In some cases, if the company has other nearby wells still in production, the well might be converted to an injection well that can accept produced water from other sites. These wells are reclassified as Underground Injection Control (UIC) Class II injection wells. Established by the Safe Drinking Water Act (SDWA) in 1974 and regulated by the U.S. Environmental Protection Agency, the UIC program sets forth requirements for different types of injection wells in order to ensure the protection of underground sources of drinking water (USDWs). Class II wells accept liquid wastes from the oil and gas industry (for more information on the UIC program, see Appendix C).
- American Petroleum Institute (API), “Environmental Protection for Onshore Oil and Gas Production Operations and Leases,” API Recommended Practice 51R, First Edition (July 2009), 17. ↩
- API, “Community Engagement Guidelines,” 9. ↩
- API, “Environmental Protection for Onshore Oil and Gas Production Operations and Leases,” 19. ↩