Silica scale inhibition experiments: Geogard SX application on geothermal brine with ultra high concentration of SiO2

Abstract

The Botong sector of Bacon-Manito Geothermal Production Field (BGPF) have undergone series of experiments to find a proper disposal scheme for the high silica effluent generated by the Osiao-Pangas (OP) wells. Application of Geogard SX (phosphino carboxylic acid copolymer), a chemical inhibitor, was evaluated in the field to determine its effectiveness in Botong separated brine which contains more than 1,100 ppm SiO2. Two different concentrations of the chemical, 10 ppm (C1) and 5 ppm (C2), were tested in the hot injection and jar experiments. The hot injection experiment was conducted using a pilot test facility. Concentration C1 was found effective in inhibiting silica deposition in pipes and on formation materials. Concentration C2, however, showed dispersive action to silica polymer but did not inhibit silica deposition. In the jar test, wherein conductively cooled brine was experimented, Geogard SX remarkably prevented further growth of the colloidal silica for a long period of time for both tested concentrations. C2 on the other hand showed longer effect compared to C1.