Investigating reservoir-scale heterogeneity in Li-enriched oil field brines of the Devonian Leduc and Nisku formations, Alberta Basin, Canada

Securing a North American lithium (Li) pipeline is pivotal to the clean energy transition and national security. The low-temperature sedimentary basin brines of the Devonian Alberta Basin, Canada are emerging as a promising unconventional domestic Li resource. This study integrates new and published geochemical and isotopic datasets from the Devonian Leduc and Nisku formation oil field brines to investigate brine origin, evolution, and Li enrichment mechanisms at the reservoir scale. Despite receiving considerably less attention than the Leduc Formation, the Nisku Formation brines display broadly similar geochemical and isotopic characteristics, suggesting common Li enrichment processes. Here we subdivide the Leduc and Nisku brines into geochemically distinct groups associated with four Devonian carbonate reef reservoirs (Redwater, Leduc, Chedderville, Bashaw) and evaluate the combined behavior of Li–B-radiogenic Sr–O–H isotope systems and major-element chemistry. Shallow reef complexes in hydraulic communication with surrounding formations contain low δ²H and δ¹⁸O values (avg. −78‰ and −3‰, respectively) and Li concentrations (avg. ∼32 mg/L), suggesting meteoric infiltration caused dilution of the Li resource. Brines from structurally deep reef complexes approaching the Rocky Mountain deformation front display high Li concentrations (avg. ∼67 mg/L), high δ¹⁸O (avg. 3.4‰) and radiogenic strontium values (avg. 0.70899), and low δ¹¹B and δ⁷Li values (avg. 24‰ and 15‰, respectively), consistent with interaction between brines and marine shales. Results suggest that Li enrichment and preservation are controlled by distinct but related processes, where shale-fluid interactions likely contribute Li to the basin brines while hydrologic isolation controls the preservation of elevated Li concentrations.

Duke Scholars

Author Avner Vengosh Earth and Climate Sciences