Key Takeaways & Executive Findings
- •• Higher water driving pressure exacerbates the deterioration of dynamic compressive strength with increasing temperature, while enhancing rate dependence except at 600 °C. • A prediction model for dynamic compressive strength deterioration considering reservoir temperature and water driving pressure is proposed for geothermal reservoirs. • Crack density increases with temperature and water driving pressure, exhibiting multiscale failure cracks parallel to the loading direction. • The study provides implications for wellbore stability under drilling disturbance and design of repeated dynamic hydraulic fracturing in geothermal development.
Abstract
The safe and efficient development of geothermal energy is a key driver of the energy revolution and environmental governance in this century. To understand the effect of water driving pressure on drilling safety and hydraulic fracturing efficiency during the development of geothermal energy under varying reservoir temperatures, dynamic compression tests were conducted on granite samples subjected to thermal treatment (25, 100, 200, 300, 400 and 600 °C) and subsequent forced water absorption (0, 4, 8, 12 MPa) using a split Hopkinson pressure bar system. The results indicate that a higher water driving pressure exacerbates the deterioration of dynamic compressive strength with increasing temperature, while it enhances the rate dependence of dynamic compressive strength, except at 600 °C. The dynamic increase factor (DIF) of dynamic compressive strength vs. strain rate is determined by both temperature and water driving pressure. A prediction model for the deterioration of dynamic compressive strength considering reservoir temperature and water driving pressure is proposed for geothermal reservoirs. While the splitting failure of samples remains unchanged, crack density increases with increasing temperature and water driving pressure, exhibiting multiscale failure cracks parallel to the loading direction. The structure effective strength model, the wing-crack propagation model, the effect of pore water pressure on dynamic stress intensity factor, and the dynamic response of forced absorbed water can collectively reveal the response mechanisms of dynamic strength. Based on the experimental findings, implications for safe and productive geothermal energy development are discussed, with particular attention to the effect of drilling fluid leakage on wellbore stability and the impact of residual fracturing fluid after backflow on repeated fracturing. This study has important reference value for understanding dynamic wellbore stability under drilling disturbance loads and for the design of repeated dynamic hydraulic fracturing schemes in geothermal energy development.
1. Introduction
Geothermal energy development has long been considered a crucial avenue for adjusting the energy consumption structure worldwide and remains a global focal point in discussions on energy and environmental issues [1]. Geothermal resources are found in deep subsurface environments, typically ranging from 3 to 7 km below the Earth’s surface, and are usually divided into hydrothermal resources and hot-dry rock resources [2]. Currently, the development of hot-dry rock geothermal energy heavily relies on the effectiveness of the enhanced geothermal system, modifying high-temperature reservoirs, where a series of basic technical challenges need to be addressed for achieving the safety and efficiency of projects [3]. Drilling and hydraulic fracturing are the consensus methods for hot-dry rock geothermal development worldwide, both involving an understanding of fundamental mechanical behaviors of reservoirs under production loads [4]. Therefore, conducting investigations on the mechanical behavior of hot-dry rock geothermal reservoirs is foundational and necessary.
In recent years, scholars have conducted a series of studies based on the possible field temperature environment effect on the mechanical behavior of geothermal reservoir rocks to provide reference...
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Yide Guo, Cheng Zhai, Xibing Li, Ming Tao, Linqi Huang, Yangchun Wu (2025). Effect of reservoir temperature and water driving pressure on dynamic behavior of geothermal reservoirs under production loads. SinoTechIntel Verified Research. https://doi.org/10.1016/j.ijmst.2025.09.004
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Frequently Asked Questions
What is the effect of water driving pressure on dynamic compressive strength of granite at different temperatures?
Higher water driving pressure exacerbates the deterioration of dynamic compressive strength with increasing temperature, while it enhances the rate dependence of dynamic compressive strength, except at 600 °C.
How does temperature affect the dynamic behavior of geothermal reservoirs?
Temperature significantly influences the dynamic compressive strength and crack density of granite, with higher temperatures leading to increased deterioration and crack density.
What prediction model is proposed in the study?
A prediction model for the deterioration of dynamic compressive strength considering reservoir temperature and water driving pressure is proposed for geothermal reservoirs.
What are the implications of the study for geothermal energy development?
The study provides insights into wellbore stability under drilling disturbance loads and the design of repeated dynamic hydraulic fracturing schemes, considering drilling fluid leakage and residual fracturing fluid effects.
What experimental method was used in the study?
Dynamic compression tests were conducted on granite samples using a split Hopkinson pressure bar system after thermal treatment and forced water absorption.
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