Experience in Scale Control With East Mesa Geothermal Brine

Abstract

American Institute of Mining, Metallurgical, and Petroleum Engineers, Inc. Abstract The East Mesa Geothermal Test Site, near Holtville, California, established by the Bureau of Reclamation, has been involved with studies of resource development and geothermal desalination since 1972. At present, there are five geothermal wells on the East Mesa Anomaly, operated by the government, as well as five others, developed by private interests. The major program at the site has been investigation of the feasibility of producing pure water from geothermal brines, using producing pure water from geothermal brines, using desalination techniques. Pilot plants installed and operated included two distillation units and a high temperature electro-dialysis unit. Throughout the last 4 years of investigation, a variety of scaling problems have been encountered. Plugging and fouling of downhole well piping, surface piping, and process units primarily with calcium process units primarily with calcium carbonate, barium sulfate, and silica have been noted. This paper discusses the conditions under which these observations have been made, including brine chemistry, brine temperature, well flow, and other process conditions. Success has been noted in the use of several scale inhibitor additives, especially in the control of calcium carbonate and barium sulfate scale. The scale inhibition techniques described in this paper should have applicability in operation of geothermal systems for both power and water production, as well as in the reinjection of waste brine. Introduction Since 1972, the U. S. Bureau of Reclamation has been operating a geothermal test facility on the East Mesa, near Holtville, California. The purpose of activities there has been to determine the feasibility of providing a source of augmentation flow for providing a source of augmentation flow for the Lower Colorado River by the desalination of geothermal brines. A unique aspect of this program is the fact that the geothermal brine provides both the source of water and heat to operate the process.