Paper contribution

Effect of Thermal-Shock Damage on Heat Extraction from Hot Dry Rock

Rugesh Kalanji; Ankesh Kumar; Jogender Singh

Proceedings
EUROCK 2026
Pages
1065-1071
Submitted
28 January 2026
Accepted
15 June 2026
Published
12 August 2026

Summary

Abstract

Heat extraction from hot dry rock (HDR) reservoirs depends on the efficiency of heat transfer between the surrounding rock mass and the circulating working fluid. In geothermal operations, rapid cooling of hot rock can occur and induce thermal-shock damage, progressively modifying the thermophysical properties of the reservoir. Although such effects are well documented in laboratory studies, their direct influence on heat extraction behavior—particularly when damage is unevenly distributed around the wellbore—remains insufficiently understood. In this study, a Thermo-Hydraulic (TH) numerical model is developed to investigate heat extraction from HDR while explicitly accounting for progressive thermal-shock damage. Five damage states are defined based on laboratory rapid-quenching experiments, and the corresponding thermophysical properties are measured after each treatment. To represent realistic near-wellbore conditions, the damaged rock is modeled as concentric layers surrounding the wellbore, allowing a layer-by-layer assessment of the thermal response. Outlet fluid temperature and heat extraction rate are used as the primary performance indicators, and all results are compared with an intact reference condition (T-25). The results indicate that thermal-shock damage strongly influences reservoir temperature evolution and outlet fluid behavior. Compared with the intact case, thermally damaged rock exhibits a higher initial heat extraction response followed by a faster decline in outlet temperature as near-wellbore heat is depleted. Increasing damage severity accelerates this decline, indicating reduced long-term thermal sustainability. Layer-based analysis further reveals that damage closest to the wellbore dominates the outlet temperature response, while outer damaged layers have a weaker influence. When multiple damaged layers are present, their interaction produces a nonlinear thermal response that cannot be captured using homogeneous rock properties. These findings demonstrate the importance of incorporating experimentally measured thermo-physical properties of thermally shocked rock into Thermo-Hydraulic (TH) models of HDR geothermal systems.

Contributors

Authors

  1. Rugesh Kalanji Indian Institute of Technology Palakkad, India ORCID 0009-0006-6893-7096
  2. Ankesh Kumar Indian Institute of Technology Palakkad, India
  3. Jogender Singh Sardar Vallabhbhai National Institute of Technology, Surat, Gujarat, India

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References

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