考虑不同尺度裂缝的页岩气耦合流动模拟

Coupling flow model of shale gas considering multiscale fracture

基于黏性流,努森扩散,真实气体效应的页岩气流动规律,对于存在不同尺度裂缝的页岩储层,考虑了页岩中基质与裂缝之间非稳态窜流的影响,耦合建立页岩气多重相互作用连续性模型(MINC)模型与嵌入式离散裂缝模型(EDFM),空间采用有限体积与时间采用有限差分方法全隐式求解。通过实例分析结果表明:吸附气对于页岩气产量影响明显,故在页岩气数值模拟过程中不能忽略吸附气的存在;天然裂缝开度变化对于页岩气产量影响明显;在水力压裂过程中,水力压裂区(SRV)体积是影响页岩气产量的主要因素。

Shale reservoirs have complex nanopore structures and multiscale cracks Based on viscous flow,Knudsen diffusion,real gas effect in shale,multiple interaction continua(MINC)model and embedded discrete fracture model(EDFM)were coupled when considering the influence of transient flow between the matrix and cracks in shale.Finite volume method and finite difference method were used to implicitly solute the partial differential equations.The results show the effect of adsorption gas on shale gas production is obvious.Therefore,the existence of adsorbed gas cannot be neglected during the simulation of shale gas;The change of natural fracture opening has obvious effect on shale gas production;In the process of hydraulic fracturing,the volume of hydraulic fracturing zone is the main factor of affecting shale gas production and natural fractures.