Chemical analyses of geothermal waters and strategic petroleum reserve brines for metals of economic importance

Waters from seven hydrothermal-geothermal, one geopressured-geothermal, and six Strategic Petroleum Reserve wells have been surveyed for 12 metals of economic importance using trace chemical analysis techniques. The elements sought were Cr, Co, Mn, Ta, Sn, V, Nb, Li, Sr, Pt, Au and Ag. Platinum was found at a concentration of 50 ppb in a brine from the Salton Sea geothermal area. Brine from this region, as has been known from previous studies, is also rich in Li, Sr and Mn. Higher concentrations (900 ppm) of Sr are found in the high-salinity geopressured brines. None of the fluids contained interesting concentrations of the other metals. Good recovery of precious metals at sub-ppm concentrations from synthetic high salinity brines was achieved using Amborane reductive resin, but similar recovery in the laboratory using real brines could not be demonstrated. Several analytical techniques were compared in sensitivity for the determination of the precious metals; neutron activation analysis with carrier separation is the best for gold and platinum in geothermal brines.