Comparison of Hydraulic Fracturing and Deflagration Fracturing Under High-Temperature Conditions in Large-Sized Granite

Abstract

Fracturing is an indispensable technique in geothermal energy development. Large-sized model tests of different fracturing methods are crucial for evaluating the fracturing effect and extrapolating the results to field applications. For common hydraulic and deflagration fracturing methods, 40 × 40 × 40 cm3 granite samples were used to carry out fracturing tests under high-temperature conditions in this paper. Through the analysis of the fracturing parameters and multiscale fracture morphology, a series of key findings were summarized. Deflagration fracturing is more intense, notably unaffected by the principal stress difference, and is capable of generating fracture spaces tens of times larger than those created by hydraulic fracturing. Furthermore, high temperatures tend to produce more fracture zones rather than continuous cracks during hydraulic fracturing. In contrast, deflagration fracturing yields simpler and more regular fractures in granite at high temperatures. Finally, the influence of the borehole number and the quantity of the deflagration agent on the fracturing effect are briefly discussed. These findings provide valuable insights for enhancing reservoir stimulation in geothermal systems.

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摘要

压裂技术是地热能开发中不可或缺的关键手段。针对不同压裂方式开展大型模型试验，对于评估压裂效果及结果外推至现场应用具有重要意义。本文以常规水力压裂与爆燃压裂为研究对象，采用40×40×40 cm³花岗岩试样，在高温条件下开展压裂试验。通过对压裂参数及多尺度裂缝形态的分析，总结出一系列重要结论：爆燃压裂作用更为剧烈，且不受主应力差显著影响，其产生的裂缝空间可达水力压裂的数十倍；高温作用易使水力压裂形成更多破碎带而非连续裂缝，而爆燃压裂在高温花岗岩中产生的裂缝形态更为简单规则。此外，本文还探讨了钻孔数量与爆燃剂用量对压裂效果的影响。研究结果为提升地热系统储层改造效果提供了有价值的参考依据。

链接：

Comparison of Hydraulic Fracturing and Deflagration Fracturing Under High-Temperature Conditions in Large-Sized Granite