An inversion method to estimate thermal breakthrough time using thermo-sensitive tracer in reservoirs with highly heterogeneous permeability

• An analytical solution is derived based on the hydrolysis of thermo-sensitive tracer for heterogeneous systems. • The TS tracer technology can accurately predict thermal breakthrough time in reservoirs with heterogeneous permeability. • The correlation coefficient between analytical predictions and simulation results exceeds 0.99. • The prediction accuracy is independent of injection conditions, reservoir porosities, and temperatures. Thermo-sensitive (TS) tracers offer significant potential for enhancing the understanding of heat transfer in porous media and ascertaining financial revenues by reducing reservoir lifetime prediction uncertainty. Based on the demonstrated feasibility of TS tracers for estimating the thermal front positions in homogeneous systems, the study expands the application of TS tracers to heterogeneous conditions. Assuming that heat and tracers follow the same preferential flow pathways, we derived an analytical solution to estimate the thermal breakthrough time in the reservoir with highly heterogeneous permeability. The analytical estimates are validated against the simulation results. The findings show a strong agreement on thermal breakthrough time, with a correlation coefficient exceeding 0.99, between the analytical estimates and simulation results. Additionally, the estimation accuracy remains robust across a wider range of injection and reservoir conditions, including the variation of injection rate, temperature, and reservoir porosity. However, the reliability of this approach critically relies on the ability to accurately interpret the tracer concentration breakthrough curve. The TS tracer technology demonstrates high feasibility only when the breakthrough curve can be effectively deconvoluted into contributions from individual preferential flow pathways.