Presentation Date: Feb 14, 2026
AGSA Abstract
Understanding heat transport in fractured geothermal reservoirs is critical for optimizing subsurface energy extraction. This study develops analytical and semi-analytical solutions to a one-dimensional, transient heat transport equation that captures both conduction in the rock matrix and convection in fluid-filled fractures. Unlike traditional models, this work integrates pressure-dependent porosity, effective thermal conductivity, and fracture heat capacity into the formulation, providing a more realistic representation of evolving reservoir conditions. The governing partial differential equation was derived from first principles, accounting for energy balance in a dual-porosity system. Analytical solutions were obtained via separation of variables, while a semi-analytical solution using Picard’s iteration allowed incorporation of nonlinearity in porosity-pressure relationships. The model was implemented in Python and validated through sensitivity analyses across key parameters: porosity, fluid velocity, and fracture pressure. Results reveal that low-porosity formations exhibit steeper thermal gradients due to reduced heat capacity and conductivity, while high porosity leads to smoother profiles. Higher fluid velocities accelerate convective heat transport, shifting the thermal front closer to the boundary. Additionally, increasing fracture pressure reduces porosity, which in turn suppresses heat transport due to decreased thermal storage. Time-dependent results illustrate a transition from rapid early-time heating to gradual convergence toward steady-state conditions. This framework serves as a fast and transparent benchmark for verifying numerical simulators and provides key insights into reservoir design and performance forecasting. By incorporating dynamic porosity effects, the model advances analytical geothermal reservoir studies and offers practical utility for evaluating transient thermal behavior under realistic operating conditions.
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