倾斜钻孔三维地应力张量反演方法及其应用研究
Determination of the three-dimensional in situ stress tensor in inclined boreholes and its application
高桂云 1王成虎 1刘冀昆 2武凝雨 1闫绍坤 2林淇七3
作者信息
- 1. 应急管理部国家自然灾害防治研究院,北京 100085
- 2. 中国地质大学(北京)工程技术学院,北京 100083
- 3. 防灾科技学院地质工程学院,河北三河 065201
- 折叠
摘要
常规水压致裂方法在倾斜钻孔应力测量尤其是三维应力测量中受到极大的限制,而原生裂隙水压致裂地应力测量方法需要大量原生裂隙才能得到合理的结果.结合倾斜钻孔中完整岩体段常规水压致裂与原生裂隙重张试验,通过优化原生裂隙面剪应力假定并结合常规水压致裂法给出的钻孔截面应力,建立观测值方程组,利用蒙特卡罗算法,实现了倾斜钻孔中三维应力张量反演,并通过天津蓟州某抽水蓄能电站倾斜钻孔的三维应力测量,验证本文方法的可靠性和准确性.研究结果表明,本文所提方法只需选择1段或以上完整岩体段常规压裂试验和1段或以上原生裂隙段重张试验,就可以得到倾斜钻孔三维应力状态.与仅采用原生裂隙水压致裂法相比,本文方法大大降低了对原生裂隙数目要求,反演得到的数据离散性小,稳定性高,且结果与区域应力状态较为一致,为单孔斜孔(或垂直孔)中三维地应力张量的获取提供新的思路与可靠途径.
Abstract
The conventional hydraulic fracturing(HF)method is greatly limited in the in situ stress measurements of inclined boreholes,especially in three-dimensional stress measurements.Moreover,the hydraulic tests on pre-existing fractures(HTPF)requires a large number of pre-existing fractures to obtain reasonable results.By optimizing the assumption of shear stresses on the primary fracture surfaces and using Monte Carlo algorithm,the three-dimensional stress tensor inversion in the inclined borehole was realized by combining the conventional HF and the HTPF tests.The reliability and accuracy of the proposed method were verified by three-dimensional stress measurements of an inclined borehole in a pumped storage power station in Jizhou,Tianjin.The results show that the proposed method can determine the three-dimensional stress tensors of the inclined borehole only by selecting 1 or more test intervals for conventional HF tests in intact rock mass and 1 or more test intervals for HTPF tests.Compared with the HTPF method that only adopts pre-existing fractures in stress determination,the proposed method greatly reduces the requirement of the number of pre-existing fractures.The inversion results have little dispersion and high stability,which are also consistent with the regional stress state.The proposed method provides a new idea and a reliable approach to determine the stress tensor using a single inclined or vertical borehole.
关键词
岩石力学/倾斜钻孔/三维应力张量/水压致裂/原生裂隙/蒙特卡罗方法Key words
rock mechanics/inclined borehole/three-dimensional stress tensor/hydraulic fracturing/pre-existing fractures/Monte Carlo algorithm引用本文复制引用
出版年
2024
NETL
NSTL
万方数据