致密油层压裂过程中裂缝延伸对地应力的影响

水力压裂技术是开发致密油层的主要方式.为了研究人工裂缝延伸过程中对地应力的影响,采用弹性力学理论中的平面应变问题和力学叠加原理,运用有限元分析方法对压裂过程中裂缝延伸对地应力的影响进行模拟研究和分析.结果表明:随着裂缝的不断延伸,其对地应力的影响变大;随着压裂时间的增加,裂缝在达到一定长度后,其增长幅度逐渐减缓;裂缝不断延伸是导致诱导应力不断增大的主要因素,而诱导应力的增加将使天然裂缝开启变得困难.因此,为了减小对后续压裂施工的影响,在不影响储层改造效果的基础上,可人为控制压裂时间以及裂缝长度,从而减小裂缝对地应力的影响.

The Influence of Fracture Extension on the In-situ Stress in Tight Oil Reservoir Fracturing Process

Hydraulic fracturing technology is the main way to develop tight oil reservoir.In order to study the effect of artificial fracture on in-situ stress during the extension process,the influence of fracture extension on ground stress during fracturing process is simulated and analyzed by using the plane strain problem in elastic mechanics theory、mechanical superposition principle theory and finite element analysis method.The results show:with the fracture extending contin-uously,its impact on ground stress becomes larger;the fracture increases with time,but after fracture reaches a certain length,its growth rate slows.Therefore,the influence of fracture on ground stress can be reduced by artificially controlling the fracturing time and fracture length to reduce the influence on subsequent fracturing construction without affecting the effect of reservoir reconstruction.This research is of great guiding significance for the construction of on-site fractu-ring.