断层对钻孔地应力测量影响的初步分析

获得初始地应力最直接最有效的方法是进行地应力测量,但在地应力测量打钻的过程中,初始地应力会遭到破坏,使得测量值与实际初始地应力值有差别.本文应用有限元方法研完了断层对打钻前后地应力变化的影响规律,考虑因素包括断层的力学性质(弹性模量、泊松比)、断层到钻孔的距离、边界应力、复合断层.研究表明,断层泊松比对初始地应力的变化影响很小,不是影响初始地应力变化的敏感因素.断层弹性模量、断层到钻孔距离、边界应力、复合断层是影响初始地应力变化的敏感因素.研究结果可为钻孔地应力测量研究提供参考价值.

Primary analysis on effects of faults on geostress measurement in borehole

Geostress measurement is the most direct and effective way to get initial geostress, but initial geostress will be destroyed in the process of drilling, which makes the measuring value different from the actual value of the initial geostress. In this paper, the effect rules of faults on initial geostress changes are studied by using the finite element method, and several factors are considered including mechanical property of faults (elastic module, Poisson ratio), the distance of faults to boreholes, border stress and compound faults. The results indicate that Poisson ratios of faults have little influence on geostress changes, it is not the sensitive factor of initial geostress changes. Elastic modules of faults, the distance of faults to borehole, border stress and compound faults are the sensitive factors of initial geostress changes. This study result provides a reference for geostress measurements in boreholes.