Application Results of Silica Extraction Technology at Kakkonda Geothermal Area and Evaluation of Extending the Life of the Reinjection Well

Abstract

Silica Extraction Technology has been developed in order to reduce the operating risks caused by silica scale deposition in injection wells and ground facilities, which is one of the big problems in geothermal power plants. The technology will enable an increase in the production of power using binary power generation through heat recovery from injection brine. Field tests were conducted by the demonstration unit at Kakkonda Geothermal Field using injection brine with silica concentrations of approximately 500 ppm and 1000 ppm. As a result, colloidal silica was successfully recovered from brine and the silica concentration in the injection brine after applying the technology was only about 230 ppm. This indicates a lowering of the risk of silica scaling. We have conducted a scaling test using original brine and silica extracted brine. As a result, silica scaling was confirmed in the column using original brine. In case of using silica extracted brine, the amount of scale is about only 20 wt% that in original brine. This indicated that this Silica Extraction Technology will be able to extend the lifetimes of ground facilities and Injection well. This paper is based on results obtained from a project commissioned by the New Energy and Industrial Technology Development Organization (NEDO).