FROM OIL TO BRINE-MINING FOR LITHIUM: THE UNIQUE QUALITIES OF THE SMACKOVER

The Jurassic Smackover limestone is one of the most prolific producing formations in North America in oil and gas, and it is poised to be equally prolific in lithium as new technologies are used to extract the critical mineral from brine.

One of the first oil and gas reservoirs discovered in 1936 using the newly invented reflection seismograph, the Smackover extends across a broad swath of southern North America, from east Texas to the Florida Panhandle and the Gulf of Mexico.

The source rock is the lower Smackover mudstone, a thick, organic-rich series of sediments that also contain thin layers of bentonite and altered volcanic ash layers. The minerals from these zones have been deemed responsible for catagenesis and cracking. Volcanics have also been considered as a candidate for the origin of the lithium which is a feature of the Smackover.

As the Smackover Trend was developed, it was found the temperatures and pressures increase with depth and create conditions ideal for thermochemical sulfate reduction. As a result, hydrogen sulfide gas is a serious problem in many reservoirs, to the point that in deeper, hotter wells, one only encounters hydrogen sulfide and carbon dioxide, but nothing of natural gas.

Today, the northern extent of the upper Smackover contains brine with concentrations of lithium that are considered economic for direct extraction through a process being implemented by Standard Lithium.

The clay minerals from the altered volcanic ash possess lithium. Within the Smackover mudstones, lithium-enriched hydrothermal fluids could have moved through open microfractures over time, basically lacing the formation with lithium, which would continue to migrate into the reservoir rock. This is a mechanism which, if valid, could open up other parts of the world to the examination of potentially lithium-enriched reservoir brines.