Controls on the concentration of lithium in oilfield brines

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Concerns over global warming have led several countries to introduce legislation that limits the future use of internal combustion engines. As a result, electric vehicles are replacing fossil fuel-powered vehicles and there is a rapidly growing demand for lithium-ion batteries to provide the necessary energy storage. This will lead to a shortage of affordable lithium resources. Oilfield brines, which are by-products of petroleum production, may contain significant concentrations of lithium and thus have the potential to help alleviate this shortage. The proposed research will be conducted in partnership with Equinor Canada Ltd., a subsidiary of Equinor ASA of Norway. The project will investigate the origin of lithium in brines associated with black shales of the Bakken Formation, which extends from southern Saskatchewan and SW Manitoba into the USA. As the underlying evaporites (a common source of Li) contain very little lithium, and the shales are enriched in it, the latter are the likely source of lithium in the brines. The purpose of this research is therefore to develop a model that will predict the partitioning of lithium between black shales and oilfield brines, and identify criteria that can be used to determine whether a particular black shale succession is likely to yield Li-enriched brines. The research will be conducted by a team selected using EDI best-practices, and will involve determining the concentration of lithium and other elements in the brines and the organic and inorganic fractions of the shales. This will be complemented by a detailed study of the shale mineralogy and a lithium isotope study that will take advantage of the strong fractionation of 6Li and 7Li known to occur between organic and inorganic shale fractions. By showing how lithium concentrations in brines correlate with those of the organic and inorganic fractions, the research will lead to a predictive model for evaluating the lithium potential of brines associated with black shales. The research will help promote the exploration for lithium brine resources in Canada and assist Equinor with the evaluation of the lithium potential of brines in the Bakken Formation in North Dakota and Saskatchewan and those currently produced from its offshore operations in Newfoundland.