摘要：为了研究多分支定向射孔水力压裂裂缝扩展形态,提出基于多孔介质渗流-损伤耦合的有限元数值模拟方法,该方法的耦合原理基于Zimmerman的孔隙弹性概念,压裂准则和裂缝张开度本构关系基于损伤局部化概念,通过介质水力学属性参数的各向异性实现孔壁裂缝成核和扩展路径识别,多场耦合迭代程序基于ANSYS平台开发,模拟平面应变裂缝(KGD)在定向射孔(一字形、十字形和Y字形)条件下的裂缝扩展形态。结果表明:定向射孔条件下裂缝扩展形态复杂的原因在于,裂缝扩展同时受制于主压应力牵引作用和定向射孔导向作用,两种作用对裂缝扩展方向竞争性拉动,加上孔底部的应力集中作用,导致裂缝呈现多种扩展形态,尤其在多分支射孔条件下,射孔裂缝分支存在竞争性和共生性两种生长机制,从而进一步加剧了裂缝形态的复杂性。

Abstract：In order to study the complex morphology of hydraulic fracturing under multi-oriented perforations, the finite element method (FEM) with creative points is proposed. The coupling principle is based on concepts of pore-elasticity proposed by Zimmerman's criterions of hydraulic fracturing and the constitutive relation of fracturing opening with fluid pressure is based on the concepts of damage localization. The identification of crack initiative positions and propagation path around the borehole is based on the anisotropic modeling of the fractured property parameters. The coupling program is developed on the platform of ANSYS. Through the program, the hydraulic fracture of plane strain (KGD) under the condition of oriented perforation (straight lineshaped, two-cross straight line-shaped and three lines in Y-shaped) is simulated. The results show that the reasons of complex configurations of the hydraulic fracturing lies in the traction of the maximum compressive principal stress, the steering traction of the oriented perforations, the competitive tractions on the fracture propagation and stress concentration on the bottom of the perforations. The combination of these result in all kinds of fracture configurations. Under the condition of multi-perforation, there are two growth mechanisms for the fracturing branches, i. e. the competitive and coexistence.

关键词：水力压裂;渗流;损伤;定向射孔;

DOI：10.16186/j.cnki.1673-9787.2018.02.018

分类号：TE257.1