Graduate Ph.D. Student
Department of Earth and Planetary Sciences
Montreal, Quebec, Canada
Lithium is a critical element for battery technology, particularly in the automotive sector, and consequently, demand for it is expected to increase sharply within the next decade. Although it has been long known that some oilfield brines have potentially economic Li concentrations, many do not. The reasons for this are poorly understood, and there are no specific tools with which to predict whether brines in a particular basin are likely to be enriched in lithium.
Several oilfields brine contain significantly higher lithium concentrations than modern-day seawater (~0.1 mg/L Li). These include the Jurassic Smackover Formation in the Gulf of Mexico (median 103 mg/L Li), the Middle Devonian Marcellus Formation (median 67 mg/L) and the Late Devonian Bakken Formation (median Li 47 mg/L Li). However, other brines, such as those found in Silurian to Pennsylvanian reservoirs in the Illinois Basin or Cretaceous reservoirs in the Western Canadian Sedimentary basin, contain very little lithium (<10 mg/L). Although there has been considerable research devoted to the hydro geochemistry of these brines, the source of the lithium is often ignored or only briefly discussed. Several hypotheses have been proposed to explain lithium enrichment in oilfield brines, but they all appear to have some weaknesses, and, importantly, these hypotheses have not been critically evaluated. The key processes commonly considered to account for the lithium enrichment in oilfield brines are the dissolution of lithium-enriched evaporites and fluid-rock interaction with lithium-bearing silicate minerals (both in sedimentary packages or igneous complexes). This talk evaluates these processes using publicly available compositional and isotopic datasets and identifies the critical factors likely responsible for lithium enrichment in oilfield brines.