Novel Reactive Tracer Injection for Tracking Thermal Front Propagation

Abstract

This study investigates the application of OU1 as a temperature-dependent reactive tracer for tracking thermal front propagation in geothermal reservoirs. To evaluate the performance of OU1 across different scenarios, we utilized CMG STARS to simulate its behavior under various reservoir temperatures and injection rates following a slug injection approach. We identified a minimum in situ flow velocity for reactive tracers to be successful in relaying information about thermal front propagation. This minimum velocity depends on the reaction kinetics, temperature, and target depth of investigation. OU1 proved to be an effective tracer for temperatures in the range of 70–90 °C, where it was found to maintain a distinct signal of produced concentration. Compared to other reactive tracers, OU1 had an intermediate reaction rate that proved to be more efficient in tracking thermal propagation than slower- and faster-reacting tracers, making it particularly suitable for direct-use geothermal systems. These findings confirm the potential of OU1 as a reactive tracer for moderate-temperature geothermal reservoirs, offering a valuable tool for thermal tracking purposes, especially because it is environmentally safe, economical, and readily available.