Geochemistry and Reinjection of Waste Waters in Vapor Dominated Fields

Abstract

The geothermal power-plants in vapor dominated fields produce large quantities of condensate. These waters have high concentrations of ammonia, boric acid and sUlphides and are therefore potential pollutants of ground-water. Reinjecting the condensate in selected wells of the field gets rid of industrial waste waters (Einarsson et al. ,1975) and may compensate in part for the natural fall in reservoir pressure caused by the negative hydrological balance between exploitation and the limited natural field recharge (Celati et al. ,1973).

The following phenomena in the reservoir induced by reinjection will be described:
a) mixing of original deep steam and reinjection-originated steam;
b) isotope fractionation of steam produced from reinjected water;
c) effects of fluid redistribution (displacement), where areal gradients of isotopic composition and gas/steam ratio are present.
d) possible cooling of rock matrix.