Further Silica Inhibition Efficiency Testing of Geogard SX at the Southern Negros Geothermal Production Field, Philippines

Abstract

A phosphino carboxylic acid co-polymer silica inhibitor, Geogard SXö (GSX), was tested to determine its effectiveness and economic feasibility in the Southern Negros Geothermal Production Field. Using a test facility, that simulates the actual brine conditions along the reinjection line and wellbore, Geogard SX was tested at a 0.50 ppm dosing concentration. After 81 days of continued dosing, the silica deposition rate along the line dropped from 10-13 mtnlyear to 4 mmæyear, which is equivalent to 70% silica inhibition efficiency. The brine flow rate of the untreated line subsequently declined by as much as 40%, while the GSX treated line were maintained within the baseline levels. Based on previous experiences with well OK3R and cost estimates at 0.50 ppm dosing concentration, the application of GSX is economical compared with conventional pipe and well maintenance procedures at a given time frame.