油层压裂模拟损伤力学数值方法及应用实例.pdfVIP

油层压裂模拟损伤力学数值方法及应用实例 1 1 沈新普 ,金生吉 (1.沈阳工业大学大学 建筑工程学院，辽宁省沈阳市 邮编；110870) 摘 要： 为了充分发挥油层改造的效力，使用塑性损伤有限单元法，模拟水力压裂产生的裂纹的扩展 和分布情况，并以此为依据，对某油田长度为 400 米的致密砂岩储层中的一条水平井多段压裂的段间 距设计进行优化选择。这里使用了标量损伤来从数学上表达注水压裂在油层中产生的微裂纹的体积密 度。数值计算中采用了固液耦合的 3 维有限元格式，来模拟渗流与变形的耦合力学行为。为了对压裂 区进行准确模拟，计算中采用了子模型技术。计算结果中给出了给定注水速率时相应的 3 维损伤演化。 同时给出了损伤场、孔隙压力场、主应力场的分布。根据数值计算结果，推荐的段间距为 80 米，这 样400 米的水平井段应该采用6 段压裂。 关键词：塑性；损伤；裂纹；水力压裂；致密砂岩；有限元；水平井；非常规石油资源；有效裂纹； Modeling Fractures with Continuum Damage and Its Numerical Application to Reservoir Formation Stimulation Estimates 1 1 SHEN Xin-pu , JIN Sheng-ji , (1. School of Architecture and Civil Engineering ，Shenyang University of Technology, Shenyang, 110870, China) Abstract: In order to obtain the best effect of reservoir formation stimulation, with plastic damage model and Finite Element Method, to simulate process of fracture evolution and its distribution under hydraulic fracturing injection. Value of interval between two stages of fracturing for a 400 m long horizontal well within tight sand formation was optimized with the numerical results obtained. The volumetric density of cracks created by injection fluid is represented here by a scalar damage variable. A coupled calculation of hydro mechanical problems with a 3D finite element method (FEM) is performed. Submodel technique was used in the calculation in order to obtain accurate solution. The numerical results for the distribution of mechanical variables, including evolution and distribution continuum damage generated by hydraulic fracturing, pore pressure, and principal s