My father consulted on this briefly back in the early 1980s. Union Oil Corp drilled numerous exploratory wells back in the day to evaluate both the geothermal and mineral potential of the field. Net result then was a no-go: Basically they're dealing with a supersaturated mineral brine at great depth, temperature and pressure. When the temperature or pressure of the system decreases, the dissolved minerals rapidly precipitate. Net result? Casing pipes rapidly clog and become blocked with hardened mineral salts.
Lots of money and time went into that exploration and it all came to naught. Union Oil had previously developed The Geysers geothermal energy field in Northern California, so they knew a thing or two about the process. It may be that technology has expanded to physically enable harnessing this resource, but I'm willing to bet it is mostly hype - like all the other domestic lithium and rare earth "projects" that appear in media briefly and the disappear faster than they arrived. Hope I'm wrong.
Then there's the California .gov angle, whereby the likelihood of something like this getting environmentally permitted there is miniscule...
Pretty big difference in the price between oil and lithium though. Might be worth it to dig it up if it's worth significantly more.
I wasn't clear apparently - they drilled it to explore the hydrothermal/geothermal and brine salt potential. Union Oil was a fully integrated energy company - hence the foray into geothermal, with a chemical processing and mining component. They had the largest natural gas fueled fertilizer operation in California at one point in time. Plant was in Yorba Linda - Imperial and Bastanchury vicinity if memory serves. They demolished and reclaimed it circa 1990s, and it then got buried under subdivisions!
Gotcha gotcha, my bad.