An injection well is an underground formation used to place fluid. These formations could be in sandstone or limestone, or could be found in shallow soil, and the wastewaters injected into them could be water, brine, wastewater or chemical water.

Injection wells are used for a wide range of purposes, including storing carbon dioxide (CO2), waste disposal, mining, enhancing oil production or preventing saltwater intrusion. The process of creating these wells dates back to the 1930s, and was initially used to get rid of unwanted brine that was created during the production of oil. By the 1950s, chemical companies were injecting their industrial waste down into deep wells as a safe and inexpensive means of getting rid of some hazardous byproducts.

Types of injection wells

There are several classes of injection wells. Here’s a quick overview of them as defined by the Environmental Protection Agency (EPA).

  • Class I: This class is for industrial and municipal waste disposal. The wells in Class I are used for disposing of these hazardous wastes in very deep rock formations, often thousands of feet below the earth’s surface. This is common in the petroleum industry, as well as for municipal wastewater treatment, food production, chemical production, pharmaceuticals and more.

  • Class II: This class is specifically for oil and gas industries. Disposal wells fall into this category, and are used for disposing wastewater from the oil and gas industry. This is the kind of injection materials we most frequently deal with at Ecoserv.

  • Class III: This class is for injection wells for solution mining. Fluids that dissolve minerals get sent into these deep wells, and the dissolved material is then pumped up to the surface for extraction. This is commonly done for salt and uranium mining.

  • Class IV: This class is for shallow hazardous and radioactive injection wells. They are used for the disposal of radioactive or hazardous waste either into or above freshwater aquifers. They have a high risk of harming drinking water supplies, which is why they were banned by the EPA in 1984 and are now only used for groundwater cleanup. There are very few of these injection wells currently in operation in the United States.

  • Class V: Class V wells are used for injecting fluids into or above underground sources of drinking water. While similar to Class IV wells, these do not feature the disposal of hazardous wastes. This is the largest class of injection wells, with more than 650,000 active Class V wells across the nation.

  • Class VI: These wells are used for geologic sequestration of carbon dioxide, injecting the CO2 deep into rock formations to be stored for the long term.

Ecoserv specializes in a wide range of waste disposal methods, including injection wells for the oil and gas industry. To learn more about our methods of waste disposal and how injection wells can be beneficial to your job site or project, we encourage you to contact our team today with any questions you have.