CHEMICAL CLEANING AT MERCURY’S GEOTHERMAL POWER PLANTS

Abstract

Chemical cleaning is the use of chemicals to remove mineral scales and deposits from plant and equipment. Chemical cleaning is a practice used regularly in the geothermal industry and is often implemented when mechanical cleaning is either not practical and/or ineffective. Chemical cleaning techniques can be utilised on both surface equipment such as heat exchangers as well as downhole in production and injection wells to remove common geothermal deposits including silica, calcite and heavy metal sulphides such as stibnite.
This paper discusses the considerations that need to be made when planning chemical cleaning work, and assessing where chemical cleaning may be of benefit to geothermal plant operators. Case studies and examples are provided of typical chemical cleaning applications utilised at Mercury’s geothermal power plants in New Zealand.