暂堵转向压裂机理有限元分析

Finite element analysis of temporary plugging and fracturing mechanism

 李玮 纪照生

 （东北石油大学石油工程学院，黑龙江 大庆 163318）

 (College of Petroleum Engineering, Northeast Petroleum University, Daqing 163318, China)

 暂堵转向压裂技术是低渗透油气田开发后期增产挖潜的新手段、新方向。文中采用有限元分析方法研究暂堵转向压裂机理，确定转向裂缝起裂位置，分析起裂压力影响因素。研究结果表明：纤维暂堵转向压裂起裂点不唯一，当最小水平应力较大时，裂缝更倾向于从井筒起裂，反之，裂缝更倾向于从初始裂缝中部起裂；破裂压力存在一个区间，当岩石破裂压力在这个区间时，转向裂缝从初始裂缝中部起裂，当岩石破裂压力高于或者低于这个区间时，转向裂缝从井筒起裂；井筒起裂点的起裂压力随着最小水平应力的增大而减小，初始裂缝中部起裂点的起裂压力随着最小水平应力的增大而增大，2个位置的起裂压力均和地层弹性模量无关。该研究对认识暂堵转向压裂机理以及提高缝网改造效率具有重要的理论价值和现实意义。

 Temporary plugging and fracturing technology is a new method and a new direction of increasing production and potential in the late period of low-permeability oil and gas field development. Finite element analysis method was used to study the mechanism of temporary plugging and steering fracturing, determine the initial fracturing position, and analyze the influencing factors of fracturing pressure. The results show that the initial fracturing point of fiber plugging and steering fracturing is not unique. When the minimum horizontal stress is larger, the fracture is more inclined to crack from the wellbore; on the contrary, the fracture is more inclined to crack from the middle part of the initial fracture; fracturing pressure has an interval; when the rock breaking pressure falls in the interval, the steering fracture cracks from the wellbore; when the rock breaking pressure is higher or lower than the interval, the steering fracture cracks from the middle part of the initial fracture; the initiation pressure of the initiation point on the wellbore decreases with the increase of the minimum horizontal stress, while the initiation pressure of the initiation point in the middle of the initial crack increases with the increase of minimum horizontal stress; the two fracturing pressures have nothing to do with the elastic modulus of formation. The study has an important theoretical and practical significance to recognizing the mechanism of temporary plugging, steering fracturing and improving the efficiency of the network transformation.

10.6056/dkyqt201604023