Fully saturated brines

Abstract

This type of subsurface water contains more solutes than solvent and is found only at depths exceeding 1000–3000 m, where it exists at high pressures and temperatures, in the form of a dark heavy liquor in rocks ranging in age from Lower Cambrian to Upper Jurassic. The eight specimens of such brines here reported are characteristically devoid of SO4 and HCO3, with K > Na and even K > Mg, at pH 2.8 to 4.6, containing up to 9 g of Br and up to 4 g Sr/lit; the Br:1 ratio is extraordinarily high and the brines are supercharged with H2S. They may be interpreted as end-products of concentration and metamorphism. Such brines, when tapped, e.g. by drilling for hydrocarbons, produde powerful salt plugs in drillholes, capable even of stopping an oil gusher, as their solutes (up to 650 g/lit) are precipitated rapidly at reduced pressures. – IGR Staff.