Estimation of Liquid Loss due to Evaporation at the Coso Geothermal Field

Abstract

Evaporative losses of produced fluid brought to the surface and stored in well-pad or power plant sumps at the Coso geothermal field has resulted in mass losses on the order of 151,833 pounds (mass) per hour. This evaporation of sump liquid is based on an estimated evaporation rate of about 89 in/yr. Using this rate over the past 17 years of project life yields an overall liquid loss due to evaporation from sump storage of 1.33 billion pounds (mass) per year, when based on the amount of liquid re-injected (50.76 billion pounds-mass per year) during that same period yields 2.6% liquid loss due to evaporation from sump storage. Also, for the 3-year period, Mar-2003 through Mar-2006, using the re-injected brine/condensate average rate for Coso of 3,999,000 pounds-mass per hour, and the rate of evaporation mass loss of 152,000 pounds-mass per hour, a value of 3.8% can be calculated representing the rate of mass loss due to evaporation with respect to the rate of reinjected brine/condensate.