射孔方式对压裂压力及裂缝形态的影响

EFFECT OF PERFORATION MODE ON THE FRACTURING PRESSURE AND CRANNY GEOMETRIC SHAPE

利用大型真三轴压裂模拟试验系统,通过模拟地层条件,监测压裂过程及其压力情况,观察裂缝的起裂及其延伸形态,进行射孔方式对压裂压力及裂缝形态的影响研究。研究结果表明,在地应力的大小和分布确定的情况下,破裂压力随着射孔角度的增大而升高,随着射孔排数的增加而降低。为有效降低地层破裂压力、提高压裂成功率及效果,射孔方位应选择0°方向,射孔密度在套管强度容许的前提下越大越好;单排射孔形成的裂缝形态较为简单,多排射孔形成的裂缝形态较为复杂,裂缝条数增加且形态各异。

Using large real triaxiality fracturing simulation experiment system,the effect of perforation mode on the fracture pressure and cranny geometric shape through simulating the stratum condition,monitoring the fracturing process and pressure and observing cranny split and stretch shape was studied in the paper.The research results showed that under the condition of invariable in-situ stress magnitude and distribution,fracture pressure would increase if the perforation angle increased,fracture pressure would decrease if the number of perforation increased.In order to efficiently decrease fracture pressure and improve fracturing success ratio and effect we should select perforation angle 0°,and under the permission of sleeve allowable strength the more the perforating density is,the better it will be.The cranny shape of Single tier perforation was simple,and the cranny shape of more tier perforation was complex.