Low Temperature Waste Water Injection Experiments at the Bac-Man Geothermal Field, Philippines

Abstract

Strict environmental standards for disposal of waste geothermal brine to surface waters has severely constrained testing of production wells at the Bacman geothermal field The alternative is to reinject waste brine but this is constrained by the high potential for silica deposition in pipelines and the receiving injection wells, even at relatively high temperatures 160 C ) By taking into account the kinetics of silica polymerisation and precipitation, it has proven possible to control deposition to occur where physical removal of siliceous solids can be conveniently undertaken Experiments in reinjecting waste brine at low (ambient) temperature have been successfully undertaken at Bacman based on these concepts Of particular importance to the process is (1) maximising the amorphous silica supersaturation of the separated water, (2) cooling the fluid as rapidly as possible, and (3) maximising the fluid residence time prior to reinjection.