水平井分段压裂射孔间距优化方法

为了使水平井分段压裂形成更为复杂的裂缝网络体系,提高油气井产量,以均质、各向同性的二维平面应变模型为基础,建立了人工裂缝诱导应力场数学模型,并结合诱导应力场中水平最大、最小主应力方向发生转向作为裂缝转向判断依据,形成了射孔间距优化方法。研究结果表明,随着裂缝间距的增大,诱导应力分量逐渐减小;裂缝间距一定时,在最小主应力方向附加的诱导应力比最大主应力方向附加的诱导应力大,两者之差呈现先增大后减小的变化趋势。对川西水平井射孔簇间距进行了优化,压裂后输气求产,与邻井选取较大射孔簇间距压裂求产对比,增产效果明显。该射孔间距优化方法对低渗透储层水平井分段压裂设计有一定的指导意义。 

Perforation Spacing Optimization for Staged Fracturing of Horizontal Well

In order to form a more complex fracture network system in staged fracturing of horizontal wells so as to improve production rate,a new optimization method for perforation spacing has been established including a mathematical model of fractures induced stress filed on the basis of homogeneous and isotropic 2D plane strain model,and the diversion of maximum and minimum horizontal principal stress direction as the fracture reorientation criterion according to the general process of staged fracturing of horizontal wells.The results showed that the induced stress decreases gradually with the increase of fracture spacing.When the fracture spacing is constant,the induced stress in the direction of minimum stress is larger than that in the direction of maximum stress,and the difference between them first increases then decreases.The perforation spacing of horizontal wells in western Sichuan Basin was optimized by this method.Compared with the surrounding wells with large spacing of perforation set,the post-fracturing production rate of the horizontal wells with optimized perforation spacing improved greatly,which demonstrates this optimization method of perforation spacing has guiding significance to the staged fracturing design of horizontal wells in low-permeability reservoirs to some extent.