定向射孔多缝压裂工艺案例分析

A case study of oriented perforating technology for the multiple crack fracturing

一种新型的压裂工艺在中国长庆油田试验成功,该工艺在层内压裂形成了2条独立裂缝,大幅增加了裂缝与油藏的接触面积,提高了产量。长庆油田开发的超低渗透油藏岩芯分析渗透率一般在0.5 mD以下,且受到储层条件、注采井网、压裂工艺等多重限制,常规压裂工艺改造难以实现该类油藏的有效开发。历经多年研究并结合自身实际,长庆油田于2006年提出了体积压裂的理念,通过在油层内造多缝扩大油藏的泄流体积以提高单井产量。室内物模试验研究射孔对压裂影响时观察到,当射孔方向与最大水平主应力方位存在夹角的情况下裂缝发生转向,即裂缝均先沿射孔孔眼方向起裂,后转向最大主应力方向。在同一油层内上下各射一排孔,两排孔方位与最大主应力方向呈一定夹角,一排偏右,一排偏左。分别对两排孔眼进行压裂,这样由于初始裂缝转向导致两条裂缝在井眼处虚拟相交,但在地层内不会重合,形成近井类似于"X"形4条裂缝,远井形成2条近于平行的裂缝。提出了一种产生多裂缝的新型压裂工艺———定向射孔多裂缝压裂。开展了大量物模试验,证实了思路的可行性,并且长庆油田在A井开展了现场压裂试验。井下微地震裂缝测试表明:形成了"X"形多裂缝;产量数据表明:定向射孔多缝压裂井相比邻井产量提高38.1%。

It has been proved by successful experimental study and application of the new fracturing technology, which create two fracture, significantly improving contact area between fracture and low permeability reservoir, and increasing productivity as well. Normally the permeability of the low permeability block in the Changqing oil field is below 0.5 mD by low - permeable cores analysis. It is a tough task to development the oil through the general methods due to geological condition, watering well distribution and fracturing technolo. Volume fracturing is proposed to increase the productivity by multiple crack fracturing since 2006 in Changqing oil field. The fracture initiated from the hole by the perforating shot, then turn the direction of the maximum level principal stress in the physical model research. Two lines of perforating shot are fired in the different depth of the oil reservoir, with an angular between the shots and the maximum level principal stress, liking letter ＂X＂, paralleling in the distance. The oriented perforating technology for the multiple crack fracturing is presented and applied in the Changqing oil field. It is proved that multiple crack created by the downhole microseismic monitoring, productivity also increased 38.1% compared to the adjacent by oriented perforating and multiple crack fracturing, the characteristics of the reservoir has been analyzed