页岩储层复杂缝网演化与空间构形研究

The propagation and space configuration of complex fracture network are key issues for the production and recovery factor of shale gas. The propagation of complex fracture network will be investigated by numerical modelling in this research. First, a fracture branch model will be developed based on virtual fracture elements, and a complex fracture simulation model will be constructed based on displacement discontinuity method, finite volume method and maximum hoop stress criterion. Second, the new model will be validated againest experiment. Finally, the propagation of complex fracture network in fluid injection and leak off process will be simulated with the new model. The effects of shale brittleness, natural fracture configuration, fluid viscosity and injection rate on the direction, distance, shape and density of the complex fracture network will be investigated. The aim of this research is to make clear of the effects of geological conditions and fracturing operation parameters on complex fracture configuration.

页岩储层水力压裂复杂缝网演化与缝网空间构形直接影响页岩气的产量和采收率。本项目拟通过数值模拟来研究缝网的演化规律。首先，提出利用虚拟裂缝来模拟裂缝分叉，并基于位移间断边界元法、有限体积法和最大环向应力准则，建立流固耦合的复杂缝网模拟系统。其次，利用室内压裂实验来验证数模的可靠性。最后，针对不同的页岩脆性、天然裂缝形态、压裂液粘度及排量等地质条件和施工参数，模拟水力压裂缝网演化过程，并在压裂模拟的基础上模拟泄压过程，进而研究缝网扩展的方向、距离、稳定性等演化规律，以及缝网形状、压裂体积、缝网密度等空间构形的影响因素。研究的最终目的在于获得储层地质条件和压裂施工参数对缝网空间构形的影响规律，为页岩储层可压裂性评价和压裂设计提供理论依据。

页岩储层水力压裂复杂缝网演化与缝网空间构形直接影响页岩气的产量和采收率。本项目拟通过数值模拟来研究缝网的演化规律。首先，提出利用虚拟裂缝来模拟裂缝分叉，并基于位移间断边界元法、有限体积法和最大环向应力准则，建立流固耦合的复杂缝网模拟系统。其次，利用室内压裂实验来验证数模的可靠性。最后，针对不同的页岩脆性、天然裂缝形态、压裂液粘度及排量等地质条件和施工参数，模拟水力压裂缝网演化过程，并在压裂模拟的基础上模拟泄压过程，进而研究缝网扩展的方向、距离、稳定性等演化规律，以及缝网形状、压裂体积、缝网密度等空间构形的影响因素。研究的最终目的在于获得储层地质条件和压裂施工参数对缝网空间构形的影响规律，为页岩储层可压裂性评价和压裂设计提供理论依据。