关键词: 水力压裂, 裂缝非平面扩展, 水平井, 物理模拟, 计算模型

Abstract: A three-dimensional model for describing hydraulic fracture reorientation near horizontal wellbore was established on the basis of maximum tensile stress criterion and the Lagrange Multiplier method. The model can be used to analyze non-planar shape of hydraulic fracture during propagation under three far-field ground-stresses and wellbore pressure. The numerical codes were developed for simulation. According to the theoretical model,laboratory experiments with rock sample of 300mm×300mm×300mm in size were made on the true tri-axis simulation equipment of hydraulic fracturing. The calculated results by the theoretical model are basically consistent with those of experiments. The fundamental patterns of three-dimensional reorientation of hydraulic fracture near wellbore were obtained. The main results of theoretical model and experimental verification showed that three-dimensional reorientation of hydraulic fracture exists near horizontal wellbore indeed,and the distance away from wellbore before fracture turning increases with increament of wellbore orientation angle. The increasing magnitude is limited. Generally it occurs within three times of wellbore diameter.

Key words: hydraulic fracture, non-planar fracture propagation, horizontal wellbore, physical simulation, calculation model