Accurate modeling of the distribution of induced fractures and pre-existing natural ones in unconventional reservoirs is essential for the analysis of the productivity of horizontal wells after fracturing. A novel approach is proposed here to establish a three-dimensional geological model of induced fractures, natural fractures and the horizontal well using a discrete random distribution method, based on micro-seismic data and natural fracture properties from the S oilfield. Taking the stress sensitivity into consideration, a coupled model calculating the fluid flow in the horizontal wellbore, the reservoir matrix and fractures were established to simulate the productivity of the S oilfield. This model was calibrated by the production data in the S oilfield, and the productivity of horizontal well under different natural fracture intensities, hydraulic fracture spacing and lengths was analyzed. The results show that the area without stimulation in the tight oil reservoir can rarely be exploited. The fluid pressure in the horizontal wellbore cannot be treated as uniform, especially when the production pressure keeps decreasing; otherwise, the cumulative production will be larger than the actual one. Increasing the hydraulic fracture length and natural fracture intensity and decreasing the fracture spacing are all beneficial to the daily and cumulative oil production. However, these methods accelerate the decline of the daily production. The production decline rate with higher natural fracture intensity was about 4 times that of lower natural fracture intensity. The natural fracture intensity and the fracture spacing are factors that are more influential to the productivity compared to the fracture length.

非常规油藏中诱导裂缝和天然裂缝的分布的准确模型对于分析压裂后水平井的产能至关重要。本文提出了一种新方法，基于微地震数据和S油田的天然裂缝特性，使用离散随机分布方法建立诱导裂缝，天然裂缝和水平井的三维地质模型。考虑到应力敏感性，建立了计算水平井眼，储层基质和裂缝的流体耦合模型，以模拟S油田的产能。该模型已通过S油田的生产数据以及在不同自然裂缝强度下的水平井产能进行了校准，分析了水力压裂的间距和长度。结果表明，致密油储层中没有增产措施的地区很少被开发。水平井眼中的流体压力无法均匀处理，尤其是当生产压力持续下降时；否则，累计产量将大于实际产量。增加水力压裂长度和自然压裂强度并减小压裂间距都有利于每日和累计采油量。但是，这些方法加速了日产量的下降。天然裂缝强度较高时的产量下降速度约为天然裂缝强度较低时的产量下降速度的4倍。