相互垂直裂缝应力阴影的影响因素及规律

The main factors and rules of stress shadow of perpendicular cracks

基于弹性力学理论,采用Galerkin有限元数值离散化方法,编制Matlab有限元程序,数值模拟两条相互垂直裂缝干扰时的"应力阴影"分布状态,其主应力与主方向分布具有关于交点(坐标原点)的对称性特征.分析了流压比值、孔隙压力、缝面流压及水平应力差值等因素对两缝间主应力及主方向的影响,通过改进变排量施工、改变压裂液黏度、油气井开采降低孔隙压力和增大注入液量等工艺,发挥应力阴影效应的优点,增加复杂缝网形成的可能性.

Based on elasticity theory,we use numerical Galerkin finite element discretization method and implement Matlab finite element code to simulate ＂stress shadow＂distributions of mutual orthogonal fractures. The principal stress and principal distributions have the symmetry characteristic on the intersection（ coordinate origin）. The relationships between stress shadow and flow pressure ratio,pore pressure,fluid pressure and horizontal stress contract are analyzed,respectively. By these techniques of variable displacement construction,changing the viscosity of the fracturing fluid,exploitation of oil and gas wells changing pump rate and fracturing fluid viscosity,reducing pore pressure and increasing the injection volume,taking the advantages of shadow effect,it is likely to produce a complex fracture network.