Advancing Reactive Tracer Methods for Monitoring Thermal Drawdown in Geothermal Enhanced Geothermal Reservoirs

Abstract

Reactive tracers have long been considered a possible means of measuring thermal drawdown in a geothermal system before significant cooling occurs at the extraction well. In this study, we examine the sensitivity of successive reactive tracer tests to reservoir cooling and demonstrate a means of analyzing tracer test results based on a simplified geometric description of a geothermal reservoir. Sensitivity tests suggest that the approach can provide valuable information about the thermal evolution of the reservoir. We propose several modifications to the basic flow-through method that could provide increased sensitivity, including push-pull tracer tests at the injection well and utilization of a tracer reaction that is quenched before background reservoir temperature is reached.