Expansion-induced fracture propagation in deep geothermal reservoirs under alternate-temperature loading

Daobing Wang, Yongcun Dong, Chunlei Wei, Qitao Zhang, Mao Sheng, Bo Yu

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Abstract


Hydraulic fracturing is a crucial technique for the extraction of geothermal energy from hot dry rock reservoirs. However, the development of such reservoirs faces significant challenges due to the high in-situ stress and strong elastic-plastic behavior of these rocks, which often result in simplified fracture geometries and subsequent low heat extraction efficiency. To address this issue, a novel reservoir treatment method based on thermal expansion and contraction principles is proposed. By applying alternating heating-cooling treatments to the reservoir, cyclic thermal stress is generated within the rock to enhance the complexity of post-fracturing fracture networks. To investigate the resultant hydraulic fracture propagation under alternate-temperature loading, a custom-developed thick-walled cylinder expansion fracturing device was employed to study the fracture propagation mechanisms in hot dry rock samples under cyclic thermal loading. The fracture network complexity was characterized by the fractal dimension method. Experimental results demonstrated that alternate thermal load cycling significantly enhances the fracture network complexity compared to conventional single-phase heat treatment. The maximum improvement in fractal dimension (3.86% increase) was observed at 500 ◦C. Under alternating temperature loads, the upper surface fractures predominantly exhibited bilateral symmetric structures. At 600 ◦C, a substantial increase in branched fractures and rock debris near boreholes occurred, indicating that alternating temperature loads significantly enhance the complexity of engineered fracture networks in hot dry rock. These findings suggest that incorporating thermal cycling into hydraulic fracturing processes can significantly improve the fracture network complexity, thereby enhancing the efficiency of heat extraction from hot dry rock reservoirs.

Document Type: Original article

Cited as: Wang, D., Dong, Y., Wei, C., Zhang, Q., Sheng, M., Yu, B. Expansion-induced fracture propagation in deep geothermal reservoirs under alternate-temperature loading. Advances in Geo-Energy Research, 2025, 15(3): 261-272. https://doi.org/10.46690/ager.2025.03.08


Keywords


Deep geothermal reservoir, alternate-temperature loading, rock mechanics, artificial fracture network, expansion fracturing

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References


Barton, C. C. Fractal analysis of scaling and spatial clustering of fractures, in Fractals in the Earth Sciences, edited by Barton, C. C., La Pointe, P. R., Springer, Boston, pp. 141-178, 1995.

Cai, J., Wei, W., Hu, X., et al. Fractal characterization of dynamic fracture network extension in porous media. Fractals, 2017, 25(2): 1750023.

Cheng, Y., Zhang, Y., Yu, Z., et al. An investigation on hydraulic fracturing characteristics in granite geothermal reservoir. Engineering Fracture Mechanics, 2020, 237: 107252.

Cheng, Y., Zhang, Y., Yu, Z., et al. Experimental and numerical studies on hydraulic fracturing characteristics with different injection flow rates in granite geothermal reservoir. Energy Science & Engineering, 2021, 9(1): 142-168.

Deng, S., Xiong, F., Liu, Y., et al. Temperature-dependent permeability model of granite after thermal treatment based on energy dissipation theory and fractal theory. Rock Mechanics and Rock Engineering, 2023, 56(9): 6321-6335.

Dong, Y., Wang, D., Qin, H., et al. Device for simulating fracture morphology of hot dry rock. CN202021009205.3, 2021.

Guo, T., Tang, S., Liu, S., et al. Numerical simulation of hydraulic fracturing of hot dry rock under thermal stress. Engineering Fracture Mechanics, 2020, 240: 107350.

Guo, T., Zhang, S., Ge, H. A new method for evaluating ability of forming fracture network in shale reservoir. Rock and Soil Mechanics, 2013, 34(4): 947-954. (in Chinese)

Hou, B., Chen, M., Li, Z., et al. Propagation area evaluation of hydraulic fracture networks in shale gas reservoirs. Petroleum Exploration and Development, 2014, 41(6): 833-838.

Irwin, G. R. Analysis of stresses and strains near the end of a crack traversing a plate. Journal of Applied Mechanics, 1957, 24(3): 361-364.

Kao, J., Jin, Y., Fu, W., et al. Experimental research on the morphology of hydraulic fractures in deep shale under high difference of in-situ horizontal stresses. Chinese Journal of Rock Mechanics and Engineering, 2018, 37(6): 1332-1339. (in Chinese)

Kumari, W. G. P., Ranjith, P. G., Perera, M. S. A., et al. Hydraulic fracturing under high temperature and pressure conditions with micro CT applications: Geothermal energy from hot dry rocks. Fuel, 2018, 230: 138-154.

Lamé, G., Clapeyron, B. Mémoire sur l’équilibre intérieur des corps solides homogènes. Journal für die reine und angewandte Mathematik, 2009, 1831(7): 381-413. (in French)

Li, C., Tu, J., Xie, H., et al. Tensile behavior and damage mechanisms of hot dry rock under thermal shock fatigue and seawater dissolution. Advances in Geo-Energy Research, 2024, 13(2): 132-145.

Liu, Y., Zhang, F., Weng, D., et al. Two-phase flow thermo-hydro-mechanical modeling for a water flooding field case. Rock Mechanics Bulletin, 2024, 3(3): 100125.

Li, Y. Simulation of the interactions between multiple hydraulic fractures and natural fracture network based on discrete element method numerical modeling. Energy Science & Engineering, 2020, 8(8): 2922-2937.

Li, Y., Hu, W., Zhang, Z., et al. Numerical simulation of hydraulic fracturing process in a naturally fractured reservoir based on a discrete fracture network model. Journal of Structural Geology, 2021, 147: 104331.

Luo, T., Liu, Y. Effects of thermal stress in hot dry rock fracturing. SPE Drilling & Completion, 2022, 37(4): 353-363.

Mandelbrot, B. How long is the coast of Britain? Statistical self-similarity and fractional dimension. Science, 1967, 156(3775): 636-638.

Ma, W., Yang, C., Ahmed, S. F., et al. Effects of thermophysical parameters of fracturing fluid on hot dry rock damage in hydraulic fracturing. Geomechanics for Energy and the Environment, 2022, 32: 100405.

Moska, R., Labus, K., Kasza, P. Hydraulic fracturing in enhanced geothermal systems-field, tectonic and rock mechanics conditions-A review. Energies, 2021, 14(18): 5725.

Moska, R., Labus, K., Kasza, P. Dynamic elastic properties, petrophysical parameters and brittleness of hot dry rocks from prospective areas of central europe. Advances in Geo-Energy Research, 2024, 14(2): 90-105.

Pan, J., Zhang, L., Ma, Y., et al. Effect of thermal cracking on the tensile strength of granite: Novel insights into numerical simulation and fractal dimension. Fractal and Fractional, 2024, 8(11): 669.

Sheng, G., Su, Y., Wang, W. A new fractal approach for describing induced-fracture porosity/permeability/compressibility in stimulated unconventional reservoirs. Journal of Petroleum Science and Engineering, 2019, 179: 855-866.

Wang, D., Dong, Y., Li, Y., et al. Numerical simulation of heat recovery potential of hot dry rock under alternate temperature loading. Unconventional Resources, 2022, 2: 170-182.

Wang, D., Dong, Y., Wang, Q., et al. Experimental study on the evolution of mechanical properties of hot dry rocks under alternating temperature loads. Geothermics, 2023a, 107: 102599.

Wang, D., Zhu, H., Micheal, M., et al. Coupled heat-fluid-solid numerical study on heat extraction potential of hot dry rocks based on discrete fracture network model. Energy Geoscience, 2023b, 4(4): 100159.

Wang, H. Hydraulic fracture propagation in naturally fractured reservoirs: Complex fracture or fracture networks. Journal of Natural Gas Science and Engineering, 2019, 68: 102911.

Wang, Q., Wang, D., Fu, W., et al. Effects of saturated f luids on petrophysical properties of hot dry rock at high temperatures: An experimental study. Geothermics, 2024a, 121: 103048.

Wang, Q., Wang, D., Yu, B., et al. Evolution of elastic-plastic characteristics of rocks within middle-deep geothermal reservoirs under high temperature. Natural Resources Research, 2024b, 33(4): 1573-1596.

Wang, S., Zhou, J., Zhang, L., et al. Numerical insight into hydraulic fracture propagation in hot dry rock with complex natural fracture networks via fluid-solid coupling grain-based modeling. Energy, 2024c, 295: 131060.

Xue, Y., Liu, S., Chai, J., et al. Effect of water-cooling shock on fracture initiation and morphology of high-temperature granite: Application of hydraulic fracturing to enhanced geothermal systems. Applied Energy, 2023, 337: 120858.

Yang, Z., Tao, M., Ranjith, P. G., et al. Multiscale damage and thermal-stress evolution characteristics of rocks with thermal storage potential under thermal shocks. Journal of Energy Storage, 2024, 83: 110631.

Yu, J., Li, N., Hui, B., et al. Experimental simulation of fracture propagation and extension in hydraulic fracturing: A state-of-the-art review. Fuel, 2024, 363: 131021.

Zhang, Z., Fu, X., Yuan, W., et al. The influence of the fractal dimension on the mechanical behaviors of the soil-rock mixture: A case study from southwest china. Fractal and Fractional, 2023, 7(2): 106.

Zheng, P., Xia, Y., Yao, T., et al. Formation mechanisms of hydraulic fracture network based on fracture interaction. Energy, 2022, 243: 123057.

Zhuang, D., Yin, T., Fu, Q., et al. Fractal fracture toughness measurements of heat-treated granite using hydraulic fracturing under different injection flow rates. Theoretical and Applied Fracture Mechanics, 2022, 119: 103340.




DOI: https://doi.org/10.46690/ager.2025.03.08

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