地质不连续体对花岗岩水力裂缝扩展路径影响机制

敖嫩; 曹志成; 王虎文; 郝文才; 王豪; 郭杰; 张全立; 陈秋; 乔伟

doi:10.13928/j.cnki.wrahe.2025.S2.075

水利水电技术（中英文） ›› 2025, Vol. 56 ›› Issue (S2) : 453 -464. DOI: 10.13928/j.cnki.wrahe.2025.S2.075

水力学

地质不连续体对花岗岩水力裂缝扩展路径影响机制

敖嫩 ¹ ,
曹志成 ²^,³ ,
王虎文 ⁴ ,
郝文才 ⁴ ,
王豪 ⁴ ,
郭杰 ⁴ ,
张全立 ³ ,
陈秋 ³ ,
乔伟 ³

作者信息 +

The influence mechanism of the discontinuous rock on the propagation path of hydraulic fractures in granite

Nen AO ¹ ,
Zhicheng CAO ²^,³ ,
Huwen WANG ⁴ ,
Wencai HAO ⁴ ,
Hao WANG ⁴ ,
Jie GUO ⁴ ,
Quanli ZHANG ³ ,
Qiu CHEN ³ ,
Wei QIAO ³

Author information +

文章历史 +

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摘要

干热岩型地热资源开发为我国能源行业发展提供了零碳负碳的解决方案，建造干热岩人工热储离不开水力压裂。与煤岩、页岩等沉积岩不同，干热花岗岩属火成岩，其中发育有岩脉、岩石分界面等地质不连续体，水力裂缝与其相交后的扩展形态难以预测和控制。基于扩展有限元法(Extended Finite Element Methon, XFEM)针对花岗岩中的地质不连续体对水力裂缝扩展路径的影响机制开展研究。结果表明：岩石基质体与地质不连续体之间的抗拉强度、杨氏模量差异越大，地质不连续体对水力裂缝的阻碍作用越明显；泊松比差异越大，越有利于水力裂缝穿透地质不连续体。对于基质体致密的花岗岩而言，较小的泵注排量有利于水力裂缝穿透地质不连续体；在最大主地应力与水力裂缝起裂方向一致的前提下，较大的地应力差异系数有利于水力裂缝穿透地质不连续体。相同地质和工程参数条件下，相比于岩脉，水力裂缝会更容易穿透岩石分界面；同时，地质不连续体胶结程度的差异也会影响花岗岩中水力裂缝的扩展路径。

Abstract

The development of hot dry rock(HDR) provides a zero-carbon and negative-carbon solution for China's energy industry. Hydraulic fracturing is one of the main means for building the geothermal reservoirs. Different from sedimentary rocks such as coal and shale, granitic hot dry rock is igneous rock, in which the geologically discontinuous rock, such as veins and rock interfaces are developed. Therefore, it is difficult to predict and control the propagation geometry of the hydraulic fractures when intersecting with these discontinuous rocks. Based on XFEM, the investigations were conducted on the influence mechanism of the discontinuous rock on the propagation path of hydraulic fractures in granite. The result show that: The greater the difference in tensile strength and Young's modulus between rock matrix and the discontinuous rocks, the hindrance effect on the propagating hydraulic fracture is more obvious. A large difference in Poisson's ratio is beneficial for hydraulic fractures to penetrate the discontinuous rock. For the granite with dense matrix, a smaller injection rate is beneficial for the hydraulic fracture to penetrate the discontinuous rock. When the maximum in-situ stress is consistent with the direction of hydraulic fracture initiation, a larger in-situ stress difference coefficient is beneficial for hydraulic fractures to penetrate the discontinuous rock. Under the same geological and engineering parameters, hydraulic fractures are more likely to penetrate the rock interface rather than rock veins. At the same time, the difference in the cementation degree of the discontinuous rock can also affect the propagation path of hydraulic fractures in granite.