Oil and Gas Wells Generate a Significant Amount of Produced Water, but the Volume and Quality of the Water Produced at a Given Well Varies

A significant amount of water is produced daily as a byproduct from  onshore drilling of oil and gas, but the volume produced by a given well  will vary depending on the type of hydrocarbon being produced, the  geographic location of the well, and the method of production used. However, because the Argonne study is  based on limited and, in some cases, incomplete data, it likely  underestimates the current total volume of produced water being  generated by oil and gas operations today. Produced Water Is Generally of Poor Quality, with the Levels of Contaminants Varying Widely

The quality of produced water from oil and gas production is generally  poor, and in most situations, it cannot be readily used for other purposes  without prior treatment. The specific quality of water generated by a given well, however, can vary  widely according to the same three factors that impact the volume of  water produced from the well: the hydrocarbon being produced, the  geographic location of the well, and method of production used. Produced Water Can Be Managed in a Number of Ways, although Underground Injection Is the Most Common Practice

Over 90 percent of the water produced during oil and gas operations is  managed through underground injection practices; the remaining water is  generally discharged to surface water, stored in surface impoundments,  reused for irrigation, or reused for hydraulic fracturing. In its 2009 report,  Argonne National Laboratory estimated, and EPA officials that we spoke  with concurred, that most produced water is managed by injecting it  underground into wells that are designated to receive this water. According to producers  and agency officials we spoke with, how produced water is managed and  treated is primarily an economic decision, made within the bounds of  federal and state regulations. EPA and the States We Reviewed Regulate the Management of Produced Water through a Variety of Means

The management of produced water is regulated by EPA and the states  we reviewed through a variety of means, depending on how the water is  disposed of or reused. Other management practices,  such as disposal of the water into surface impoundments, irrigation, and  reuse of the water for hydraulic fracturing, are primarily regulated by the  state authorities. Underground Injection Is Regulated under the Safe Drinking Water Act

The management of produced water through underground injection is  subject to the Safe Drinking Water Act’s Underground Injection Control  program. This program is designed to prevent contamination of aquifers  that supply, or could supply in the future, public water systems by  ensuring the safe operation of injection wells. Under this program, EPA or  authorized states generally require producers to obtain permits for their  injection wells by, among other things, meeting technical standards for  constructing, operating, and testing and monitoring wells. Federal research also has focused on developing and describing new  and existing technologies for treating produced water. Federal Research Efforts Have Examined the Characteristics of Produced Water

Several federal agencies, including USGS, the Bureau of Reclamation, a  number of DOE national laboratories, and EPA, have issued or  sponsored studies describing the characteristics of produced water from  oil and gas operations––particularly the volume and quality of produced  water. None of these agencies provided written  comments to include in our report; however, the Environmental Protection  Agency and the Department of the Interior provided technical comments,  which we incorporated as appropriate. Appendix I: Scope and Methodology

Our objectives for this review were to describe (1) what is known about  the volume and quality of produced water from oil and gas production; (2)  what practices are generally used to manage and treat produced water,  and what factors are considered in the selection of each; (3) how the  management of produced water is regulated at the federal level and in  selected states; and (4) what federal research and development efforts  have been undertaken during the last 10 years related to produced water. In addition, we interviewed federal and state regulatory officials; federal  scientists from the Environmental Protection Agency’s (EPA) Office of  Research and Development and the Department of Energy’s (DOE)  Argonne National Laboratory, Los Alamos National Laboratory, National  Energy Technology Laboratory, Oak Ridge National Laboratory, and  Sandia National Laboratories; officials from oil and gas exploration and  production companies; officials from water treatment facilities; and other  experts with experience related to produced water. Produced Water Management and Beneficial Use.
Why GAO Did This Study

Water is a significant byproduct associated with oil and gas exploration and production. This water, known as produced water, may contain a variety of contaminants. If produced water is not appropriately managed or treated, these contaminants may present a human health and environmental risk.
GAO was asked to describe (1) what is known about the volume and quality of produced water from oil and gas production; (2) what practices are generally used to manage and treat produced water, and what factors are considered in the selection of each; (3) how produced water management is regulated at the federal level and in selected states; and (4) what federal research and development efforts have been undertaken during the last 10 years related to produced water. To address these objectives, GAO reviewed studies and other documents on produced water and interviewed federal and state regulatory officials, federal scientists, officials from oil and gas companies and water treatment companies, and other experts. GAO focused its review on the nine states that generate nearly 90 percent of the produced water, and conducted site visits in three states.

What GAO Found

A significant amount of water is produced daily as a byproduct from drilling of oil and gas. A 2009 Argonne National Laboratory study estimated that 56 million barrels of water are produced onshore every day, but this study may underestimate the current total volume because it is based on limited, and in some cases, incomplete data generated by the states. In general, the volume of produced water generated by a given well varies widely according to three key factors: the hydrocarbon being produced, the geographic location of the well, and the method of production used. For example, some gas wells typically generate large volumes of water early in production, whereas oil wells typically generate less. Generally, the quality of produced water from oil and gas production is poor, and it cannot be readily used for another purpose without prior treatment. The specific quality of water produced by a given well, however, can vary widely according to the same three factors that impact volumehydrocarbon, geography, and production method.
Oil and gas producers can choose from a number of practices to manage and treat produced water, but underground injection is the predominant practice because it requires little or no treatment and is often the least costly option. According to federal estimates, more than 90 percent of produced water is managed by injecting it into wells that are designated to receive produced water. A limited amount of produced water is disposed of or reused by producers in other ways, including discharging it to surface water, storing it in surface impoundments or ponds so that it can evaporate, irrigating crops, and reusing it for hydraulic fracturing. Managing produced water in these ways can require more advanced treatment methods, such as distillation. How produced water is ultimately managed and treated is primarily an economic decision, made within the bounds of federal and state regulations.
The management of produced water through underground injection is subject to the Safe Drinking Water Acts Underground Injection Control program, which is designed to prevent contamination of aquifers that supply public water systems by ensuring the safe operation of injection wells. Under this program, the Environmental Protection Agency (EPA) or the states require producers to obtain permits for their injection wells by, among other things, meeting technical standards for constructing, operating, and testing and monitoring the wells. EPA also regulates the management of produced water through surface discharges under the Clean Water Act. Other management practices, such as disposal of the water into surface impoundments, irrigation, and the reuse of the water for hydraulic fracturing, are regulated by state authorities.
Several federal agencies, including EPA; the Department of Interiors Bureau of Reclamation and U.S. Geological Survey; and a number of Department of Energy national laboratories, have undertaken research and development efforts related to produced water. These efforts have included sponsoring and issuing studies that describe the volume and quality of produced water, options for managing produced water and associated regulatory issues, as well as options for improving existing technologies for treating produced water and developing new technologies, such as more cost-effective filters.

What GAO Recommends

GAO is not making any recommendations. A draft was provided to the Departments of Energy and the Interior, and EPA for review. None of these agencies provided written comments. EPA and Interior provided technical comments, which we incorporated as appropriate.