基于均匀化方法的砂砾岩储层水力裂缝三维延伸模拟研究

3D Hydraulic Fracture Propagation Simulation Based on Homogenization Method in Glutenite Reservoir

由于砾石的存在,与储层基质间存在多尺度差异,砂砾岩储层水力压裂裂缝扩展形态不明确,储层改造效果差,水力裂缝扩展的数值模拟有利于提高砂砾岩储层压裂成功率。将储层表征为“基质-交界面-砾石”复合模态,利用随机分布函数及Monte-Carlo抽样方法,完成砂砾岩储层数学表征。利用均匀化理论,得到砂砾岩储层宏观等效弹性张量,有效降低多尺度导致的计算量弊端。以Palmer拟三维水力裂缝扩展模型为基础,完成砂砾岩储层水力压裂裂缝三维扩展数值模拟研究。分析表明:地层应力差、施工排量与压裂液黏度均影响裂缝三维扩展;随着应力差的增大,水力裂缝高度呈现明显下降趋势,且裂缝长度和宽度均随之增加;随着施工排量的增大,水力裂缝高度、裂缝长度和宽度均随之增加;随着压裂液黏度的增大,水力裂缝高度与宽度呈现明显下降趋势,裂缝长度反而随之增加。

Due to the existence of gravel, glutenite reservoir has serious multi-scale computation with an undefined fracture morphology, which results in poor reservoir reconstruction effect. The numerical simulation of hydraulic fracture propagation helps to improve successful rate of glutenite reservoir fracturing. With a “matrix-interface-gravel” composite state, the mathematical representation of glutenite reservoir is achieved by using random distribution function and method of Monte-Carlo sampling. The study gets macro equivalent elastic tensor of glutenite reservoir by using homogenization method and reduces the disadvantages caused by multi-scale computation. Based on the model of Palmer quasi three dimensional hydraulic fracture propagation, the numerical simulation of three-dimensional hydraulic fracture propagation is completed. The analysis shows that the following aspects,including difference of formation stress, displacement of construction and fracturing fluid viscosity,can influence fracture propagation. The height of fracture presents an obvious downward trend and the length and width increase with a rising stress difference. With an increasing displacement of construction, the height, length and width of fracture also rise. With an increasing viscosity of fracturing fluid, height and width of hydraulic fracture appear obvious downtrend while the length increases.