New Approaches to Produced Water Sampling, Analysis, and Remediation at ORNL

Oil and natural gas production is often accompanied by large amounts of wastewater [1]. The volumetric ratio of water-to-oil will increase over the lifetime of an operation and can eventually exceed 90%. Water is also associated with some, but not all, gas production. For instance, dry sources of gas are found in Alberta, Canada. Produced water is often reinjected into the well to increase oil recovery. However, in the western states, the injected water is supplemented by “clean” groundwater—thus depleting a scarce resource. Water associated with fossil fuel production constitutes a high-volume waste stream, on the order of a trillion barrels of water a year [2]. Organic contamination from soluble and dispersed oil is monitored by the U.S. Environmental Protection Agency (EPA) for offshore production. Salinity, rather than organic contamination, is the primary concern for onshore discharge, although organics cause difficulties with some salt-removal methods, such as reverse osmosis. A thorough review of produced water issues and the research that has been undertaken to solve these problems was published in 2004 by Veil and coworkers [3]. Oak Ridge National Laboratory (ORNL) and other national laboratories, with the support of the U.S. Department of Energy (DOE), have been involved with produced water remediation technologies for several years. At ORNL, chemical engineering research has been applied to removal of organics from contaminated water (centrifugal separator, ozonation, and contacts with novel solvents such as ionic liquids). Water-soluble organics and inorganic ions have been analyzed and modeled using thermodynamic and statistical methods. Most of these projects have been supported by DOE/Fossil Energy (DOE/FE) through its oil program. Recent results from ORNL produced water studies, both experimental and theoretical, will be presented. The application of these investigations to technologies supporting both water conservation and energy initiatives will be explored.