体积压裂裂缝对地应力场干扰规律的研究

Study of the Interference Law of Volume Fracturing Fracture to the Stress Field

为了研究体积压裂在低渗透油藏的开发效果,采用有限元分析并利用Comsol对体积压裂过程中的地应力扰动进行模拟,分析了地应力的分布、裂缝长度、裂缝的净压力、简单缝和复杂缝对地应力扰动的影响,以及裂缝长度、弯缝与直缝的应力扰动及影响分析,获得了地应力扰动的影响因素与影响规律。研究表明:裂缝长度、裂缝净压力和裂缝形态是影响应力扰动的主控因素,应力扰动的幅度值与这些因素呈现正相关;同时建立了不同裂缝长度,最大和最小主应力扰动差值的图版,可用此图版来确定不同裂缝长度条件下复杂缝网产生的位置;直缝对弯缝的扰动值较直缝更小。

To study the developing effect of volumetric fracturing in low permeability reservoir, the finite element analysis is conducted in this paper. The stress disturbances in the volume fracturing process are simulated with Comsol to analyze the influence of stress distribution, fracture length, fracture net pressure, simple fracture and complex fracture on the stress disturbance. Along with the analysis of crack length, the stress disturbance of bending fracture and straight fracture, the longitudinal and influencing factors and the corresponding working regularity are obtained. Research shows that the fracture length, fracture net pressure and fracture morphology are the main control effects of stress disturbances; the stress perturbation amplitude values are positively correlated with these factors. At the same time, the charts of different crack length, the maximum and minimum principal stress difference curves are established, which helps to determine the position of complex fracture network, under different crack length conditions, to enable the value of longitudinal perturbation to bending joint to be less than the straight one.