Production of minerals from oil and gas produced waters: Current state of the science

Extraction of valuable mineral commodities from waters co-produced during oil and gas extraction is a possible approach to subsidize waste disposal and/or treatment costs. Minerals including salt (sodium chloride), bromine, iodine, lithium, and magnesium compounds are domestically extracted from salt lakes and basinal brines. In addition, significant effort has gone toward mineral extraction from seawater and seawater desalination products along with closely associated research. Produced waters potentially represent more valuable minerals sources than the ocean, owing to salinity values up to and exceeding 10x that of seawater. Evaluation of pre-existing mineral concentration data for the United States, indicates that magnesium, potassium, and soda ash are typically the most valuable constituents (>$1/BBL in some cases; 1 BBL = 42 gallons), relative to elements that have gained recent interest (e.g., lithium and rare earth elements). Concentration data for trace and critical minerals (e.g., rare earth elements) in produced waters are sparse, and attempts to quantify them are hampered by a lack of methods verified for highly salinity, large analytical uncertainties, and a dearth of appropriate reference standards. Thus, for most trace and critical minerals in brine, poor coverage of reliable data and a lack of ore deposit models puts them in a pre-exploration phase. Methods to remove trace minerals from produced waters require management of variable water composition, due to time- and spatially-dependent chemistry, and overcoming fouling or other reactions caused by organic compounds and redox reactive constituents. Conversely, attempts to remove major minerals from water leads to generation of large quantities of salt and potential buildup of radionuclides. Mineral production from produced waters will not solve waste management issues but introduces a potential to reduce waste and defray disposal costs.