老井重复压裂效果评价

Evaluations of repeated fracturings in old wells

针对长庆油田部分老井重复压裂改造后产量仍无明显提升的问题,采用微地震井中监测技术,分析区域应力与裂缝产生方向,从转向技术、定向射孔技术的应用等方面评价老井重复压裂效果。研究认为,由于长期注采使老井局部应力发生改变,需对应力方向有清晰的认识,再选择合适的压裂方案;而老井重复压裂所采取的添加暂堵剂、定向射孔等压裂方式均能在射孔点附近对压裂裂缝形成一定的转向效果,但距射孔点较远的区域,裂缝仍主要沿最大主应力方向扩展。该认识为老井重复压裂工艺的优化提供指导。

The oil and gas production from some old wells in Changqing Oilfield has not significantly increased after the re-fracturing.To understand this issue,we use microseismic monitoring to analyze repeated fracturing effects.We evaluate re-fracturing effects based on local stress rather than the steering and perforation.The local stress of old wells changes with long-term injection.It is necessary to have an understanding of the stress direction changes and then choose the appropriate fracturing scheme.The temporary plugging agent and directional perforation used in the old well can form certain turning effects on fractures near the perforation point,but in an area far from the perforation point,the fracture still extends along the direction of the maximum principal stress.This understanding provides guidance for the repeated fracturing optimization of old wells.