考虑射孔孔眼磨蚀对多裂缝扩展的影响规律

Influence laws of perforation erosion on multi-fracture propagation

我国非常规油气资源丰富,压裂技术是其开发的重要手段,其中极限限流压裂技术是促进水平井压裂段均匀改造的关键技术,但井下监测表明射孔孔眼动态磨蚀严重,制约了工艺应用效果。为了解决射孔孔眼动态磨蚀带来的多裂缝扩展形态不确定性影响,提高现场工艺实际应用效果,在水平井多裂缝竞争扩展模型基础之上耦合孔眼动态磨蚀模型,然后根据实际井下射孔成像数据校正数值模型,研究了孔眼磨蚀作用下多裂缝扩展行为以及限流射孔参数优化方法。研究结果表明:(1)孔眼磨蚀作用将显著增大孔眼直径和流量系数,迅速降低射孔摩阻,加剧各簇流量分配和多裂缝扩展的非均匀程度;(2)段内应力均匀分布时,孔眼磨蚀作用随着限流作用增强而增加;(3)段内应力非均匀分布时,高应力簇裂缝扩展容易受到抑制作用,考虑孔眼磨蚀作用后将进一步加剧各簇裂缝流量分配的非均衡程度,甚至导致高应力簇裂缝停止进液,裂缝不能充分扩展。结论认为,研究结果对孔眼动态磨蚀机理研究以及改进压裂工艺设计具有重要理论和现实意义,有助力我国非常规气油气的高效开发。

There are abundant unconventional oil and gas resources in China.Fracturing technology is an important means to develop unconventional oil and gas resources,and limited-entry fracturing technology is the key technology to promote the uniform stimulation of horizontal well fracturing sections.Downhole monitoring,however,indicates serious dynamic perforation erosion,which restricts the application effect of limited-entry fracturing.In order to solve the impact of dynamic perforations erosion on multi-fracture propagation uncertainty and improve the practical application effect of field technology,the dynamic perforation erosion model is coupled on the basis of the horizontal well multi-fracture competitive propagation model.Then,the numerical model is corrected according to the actual downhole perforation imaging data,and the multi-fracture propagation behavior under the effect of the perforation erosion and the optimization method of limited-entry perforation parameters are studied.And the following research results are obtained.First,perforation erosion significantly increases the perforation diameter and discharge coefficient and rapidly reduces the perforation friction,so as to aggravate the non-uniformity of flow distribution in different clusters and multi-fracture propagation.Second,when the stress in the stage is evenly distributed,the perforation erosion increases with the increase of the limiting-entry effect.Third,when the stress in the stage is not evenly distributed,the propagation of high-stress fractures tends to be inhibited easily.The perforation erosion can further aggravate the imbalance of flow distribution in different fracture clusters and even stop the fluid from entering the high-stress fractures,so fracture propagation is not sufficient.In conclusion,the research results are of great theoretical and practical significance in studying the mechanisms of dynamic perforation erosion and improve the fracturing process design,which is conducive to the efficient development of unconventional oil and gas in China.