非常规油气藏压裂水平井动态缝网模拟方法及应用

Simulation of dynamic fracture network in fractured horizontal well for unconventional reservoirs:Theory and application

非常规油气藏压裂水平井投产后,储层压力变化导致压裂缝产生形变,表现出动态缝网特征,对油气井产能具有重要影响。为准确模拟动态缝网对非常规油气藏开发的影响,提高开发方案设计水平,首先构建了描述裂缝宽度时变性及裂缝宽度非均匀分布的裂缝形变数学模型,可同时模拟裂缝宽度和长度的变化;然后采用传导率修正技术,将裂缝形变数学模型与离散裂缝数值模拟模型进行耦合,形成了可模拟动态缝网的油藏数值模拟器;最后将模拟器应用于典型模型和实际压裂水平井模型的模拟,构建了不同生产时期的动态缝网模型,明确了动态缝网对生产井产量的影响规律。模拟结果表明,考虑动态缝网的数值模拟生产动态与实际生产动态符合率更高。

When a fractured horizontal well in unconventional reservoirs is brought online,change in reservoir pressure may lead to fracture deformation,resulting in the formation of dynamic fracture network that greatly affects well productivity.To simulate the effect of dynamic fracture network on the development of unconventional reservoirs and improve the designation level of development strategy,the study builds a mathematical model to characterize the time variant and the heterogeneous distribution of fracture width,which can simultaneously simulate the changes of fracture width and fracture length in a reservoir.Then,the conductivity modification technique is adopted to couple the fracture deformation model with discrete fracture simulation model.A reservoir numerical simulator that can model dynamic fracture network is then developed.Finally,the simulator is applied to simulation of a typical reservoir model and an actual fractured horizontal well model,respectively.Dynamic fracture network models for different production periods are thereby obtained,and the effect of dynamic fracture network on the well productivity is clarified.In all,the simulation results indicate that the simulated performance is in better agreement with practical well performance when the fracture deformation is considered in the simulator.