Produced water is a byproduct of oil and gas production. In 2016, Utah produced approximately 30.5 million barrels of oil and 158.8 million barrels of produced water, equating to roughly 5.2 barrels of produced water for every barrel of oil.
Produced water contains salts, petroleum residue and naturally occurring inorganic and organic chemicals. The proper handling of produced water is a critical part of the petroleum production process and must be disposed of in permitted facilities designed exclusively for oil and gas production water.
In Utah, two types of facilities exist for the disposal of produced water. Evaporative ponds, approximately one to eight acres by 15 feet deep, are doubled lined with synthetic liners and leak detection systems. These facilities have very strict regulations and are monitored on a regular basis by the Division (Rule R649-9 Waste Management and Disposal). In this process, the water is evaporated and the residual solid material is left behind and will be disposed of when the facility is closed. Approximately 5 percent of all produced water goes into evaporative ponds.
Class II injection wells are the second type of disposal facility where produced water is injected back into the ground. The Division has primacy from the Environmental Protection Agency (EPA) for regulating these injection wells on non-Indian countr
y in Utah. The Division has very strict regulations defining criteria for wells that can be permitted as a Class II injection well (Rule R649-5. Underground Injection Control of Recovery Operations and Class II Injection Wells).
A detailed analysis of engineering, geology, nearby water sources both surface and ground are all considered to determine the integrity of the well before a permit is given. Analysis ensures that water injected into an accepting rock formation will prevent wastewater from migrating to the surface or to ground water. In Utah approximating 95% of produced water is disposed of in class II injection wells.
Recently, class II injection wells have been associated with induced seismicity or earthquakes in Oklahoma, Arkansas, Texas, Ohio and Kansas. Current studies conclude that earthquakes are associated with large volumes of water disposal and unique geological conditions. The volumes and geology are significantly different in Utah than that of the mid-west. Utah has not experienced induced seismicity from water injection, but the Division will continue to monitor and react if conditions change.
Management of produced water is critical to the success of a well. If costs become too large, the well becomes uneconomic and resources are left in the ground. With further study and technological advancements, new methods can make this process more efficient and increase safety. The treatment and processing of produced water can benefit industry, the environment and Utah’s citizens.