水力深穿透射孔对压裂裂缝形态影响的数值模拟

基于各向异性弹性力学,结合流体力学理论,建立水力深穿透射孔条件下各向异性地层中垂直裂缝扩展的力学模型,基于最大周向应力准则建立裂缝扩展路径的计算方法,利用牛顿迭代法求解数值模型,并通过算例验证模型及求解方法的正确性。结果表明:裂缝转向半径随着射孔长度及射孔角度的增加而增大,随着压裂液黏度及排量的增加而增大;对称布孔方式优于单侧布孔方式,裂缝转向半径随着弹性模量各向异性差值的增加而增大,随着弹性模量的增大而增加。

Numerical simulation of hydraulic deep jet perforation on fracture propagation and orientation

A fracture propagation model in the process of deep jet perforation was established based on the anisotropic elasticity theory and the principles of fluid mechanics in porous media, and a method for determining the propagation angle of the fractures was proposed referring to the maximum hoop stress theory. A Newton method was used to solve the numerical model, which has been verified by case studies. The results show that the radius of the reoriented fractures increases with the increase of the jet perforation length and jet angle, and it also increases with the increase of the pumping rate and viscosity of the fracturing fluid. Symmetric jet perforation is better than the perforation in one side. The fracture reorientation radius increases with the anisotropic ratio and the elastic modules, while it decreases with the increase of the stress difference.