Lithium recovery from U.S. oil and gas produced waters: resource quality and siting considerations

Abstract

To meet the growing demand for lithium sustainably, secondary resources must be explored. Among nontraditional resource alternatives, brines co-produced from oil and gas (O&G) operations are of particular interest owing to their abundance and considerable lithium concentrations. Whereas previous work has highlighted potential O&G brines of interest for lithium extraction, the criteria to distinguish optimal from suboptimal O&G produced waters are still unclear. In the following, we provide perspectives on assessing the feasibility and challenges of produced waters from key U.S. formations as lithium resources based on their water chemistry, production rates, and geographic placement. Specifically, we clarify the impact of production rates on the estimated lithium resources and how it may aggrandize evaluations. We assess how key secondary cation concentrations and ratios complicate downstream separation, and evaluate the role of the geographic coexistence of lithium resources and lithium consumers (i.e., the manufacturing sector). Among the U.S. O&G formations evaluated herein, the Marcellus shale emerges as an attractive formation for lithium extraction, with an estimated annual lithium metal output of 930 metric tons and lower secondary cation concentrations. The potential feasibility of brines from the Marcellus formation is enabled by its reduced need for downstream separation and purification, as well as its proximity to major lithium end-user facilities (i.e., battery manufacturers). Overall, we provide an initial set of criteria to help evaluate O&G formations for their potential to serve as lithium resources and provide an assessment of the lithium resources in key U.S. O&G plays.