Radon Emanation in Geothermal Reservoirs

Abstract

Evaluation of geothermal reservoir transport properties measured by tracer concentrations at the wellhead require two types of data, flow data to characterize the hydrodynamic conditions of the reservoir and source term data to characterize the availability of the tracer for flow to the wellhead. To characterize the source term conditions for radon as a natural internal tracer for reservoir assessment studies, a comprehensive experimental analysis of radon emanation is underway. A three unit geothermal reservoir model has been constructed to measure the emanation of radon as a function of reservoir rock type, rock size distribution, convecting fluid density, temperature and pressure. Results of the calibration of the system and the first experiments with non-wetting , non-polar fluid in graywacke rock are presented to show the feasibility of the system to measure emanating power of radon under varying geothermal reservoir thermodynamic conditions.