原生裂隙水压致裂原地应力测量的理论与实践新进展

发布时间：2018-05-22 11:10

本文选题：水压致裂 + 修正HTPF法　；参考：《岩土力学》2017年05期

【摘要】：HTPF法测试所需的数目众多的原生裂隙面大大制约了这种方法的推广应用。针对这一问题,通过为原生裂隙面上广泛存在的剪应力建立力学方程,利用最小二乘法和计算机程序试错搜索原生裂隙面摩擦系数的办法反演原地应力张量。理论上基于每个原生裂隙面的水压致裂测试结果可以建立两个力学方程,那么只需要3条原生裂隙就可以求解原地应力张量,但为了保证计算机程序反演收敛,至少需要5条原生裂隙,这一方法被定名为M-HTPF法。将这种方法在山东某科研钻孔的原地应力测量作业中进行了应用,通过利用5条原生裂隙面上的水压致裂测试得到的关闭压力和方位角数据,反演得到原地应力张量:σ_1=8.85 MPa,方位角为N58.12°W∠14.18°;σ_2=6.61 MPa,方位角为N26.2°E∠-21.54°;σ_3=5.01 MPa,方位角为N62.86°E∠63.86°。通过与同一钻孔内的经典水压致裂法的测量结果对比可知,两种方法得到的最小主应力和中间主应力非常接近,最大主应力则相差较大;两种方法获得的最大、最小主应力方位角基本一致。该方法为单孔三维水压致裂原地应力测量提供了新的思路和途径。
[Abstract]:The application of HTPF method is greatly restricted by the large number of primary fracture surfaces. In order to solve this problem, the mechanical equation is established for the shear stress widely existing on the primary fracture surface, and the original stress Zhang Liang is retrieved by using the least square method and the computer program to search the friction coefficient of the original fracture surface. Theoretically, two mechanical equations can be established based on the hydraulic fracture test results of each primary fracture surface, and only three primary fractures can be used to solve the in-situ stress Zhang Liang, but in order to ensure the inversion convergence of the computer program, At least 5 primary fissures are required, and this method is called M-HTPF method. This method has been applied to the in-situ stress measurement of a scientific research borehole in Shandong Province. The closing pressure and azimuth data obtained from the hydraulic fracturing test on 5 primary fracture surfaces are used. The in situ stress (Zhang Liang) is obtained as follows: 蟽 _ S _ (1) 8.85 MPA, azimuth is N 58.12 掳W ~ (18) ~ 14.18 掳, 蟽 _ S _ 2 is 6.61 MPA, azimuth is N _ (26.2 掳E) -21.54 掳, 蟽 _ 3 is 5.01 MPA, the azimuth is N _ (62.86) 掳E ~ 63.86 掳. By comparing with the results of the classical hydraulic fracturing method in the same borehole, it can be seen that the minimum principal stress and the intermediate principal stress obtained by the two methods are very close, the maximum principal stress is quite different, and the maximum principal stress obtained by the two methods is the largest. The minimum principal stress azimuth angle is basically the same. This method provides a new idea and approach for measuring in situ stress of three dimensional hydraulic fracturing with single hole.
【作者单位】：中国地震局地壳应力研究所;中国地震局地壳动力学重点实验室;广东省地质科学研究所;
【基金】：国家自然科学基金资助项目(No.41274100) 中央级科研院所基本科研业务专项资助项目(No.ZDJ2012-20)~~
【分类号】：TU45

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