An Introduction to Saltwater Disposal Wells

Deposits of oil and natural gas in porous layers of rock and shale often occur alongside large quantities of saltwater. In order to bring these resources to the surface for further production, oil and gas companies must first remove the surrounding saltwater, which is also known as produced water or oilfield brine. This liquid contains high levels of salt as well as industrial compounds and hydrocarbons. While there are various ways to dispose of the saltwater and flowback fluid resulting from hydraulic fracturing, improper disposal may pose a threat to subterranean and aboveground fresh water.

Firms may choose to recycle the saltwater via evaporation or distillation. However, these processes often require a significant, consistent flow of water in order to serve as financially viable disposal strategies. While this is possible in regions with a large number of producing wells and an established saltwater pipeline infrastructure, recycling does not account for 100 percent of saltwater disposal, thus necessitating additional disposal methods.

Oil and gas companies may opt to use saltwater disposal wells, injecting the saltwater into non-producing underground formations of porous rock. This practice requires layers of impermeable strata both above and below the disposal well to protect shallow fresh water and is used extensively throughout Texas, where it falls under the jurisdiction of the Railroad Commission of Texas. The agency has mandated that saltwater disposal wells must contain several layers of cement and steel to protect usable fresh water at shallow depths, and it has outlined three distinct layers of well casing. The commission also restricts the establishment of saltwater disposal wells to locations that already contain naturally occurring saltwater.