Boundary scheme for lattice Boltzmann modeling of micro-scale gas flow in organic-rich pores considering surface diffusion

作     者：Hong Zuo Shou-Chun Deng Hai-Bo Li 左鸿;邓守春;李海波

作者机构：State Key Laboratory of Geomechanics and Geotechnical EngineeringInstitute of Rock and Soil MechanicsChinese Academy of SciencesWuhan 430071China University of Chinese Academy of SciencesBeijing 100049China 

出 版 物：《Chinese Physics B》 (中国物理B（英文版）)

年 卷 期：2019年第28卷第3期

页      面：84-96页

核心收录：

学科分类：081803[工学-地质工程] 08[工学] 0818[工学-地质资源与地质工程] 

基　　金：supported by the Strategic Program of Chinese Academy of Sciences(Grant No.XDB10030400) the Hundred Talent Program of Chinese Academy of Sciences(Grant No.Y323081C01) the National Natural Science Foundation of China(Grant No.51439008) 

主　　题：lattice Boltzmann method(LBM) surface diffusion Langmuir slip model boundary scheme 

摘      要：We propose a boundary scheme for addressing multi-mechanism flow in a porous medium in slip and early transition flow regimes, which is frequently encountered in shale gas reservoirs. Micro-gaseous flow in organic-rich shale involves a complex flow mechanism. A self-developed boundary scheme that combines the non-equilibrium extrapolation scheme and the combined diffusive reflection and bounce-back scheme(half-way DBB) to embed the Langmuir slip boundary into the single-relaxation-time lattice Boltzmann method(SRT-LBM) enables us to describe this process, namely, the coupling effect of micro-gaseous flow and surface diffusion in organic-rich nanoscale pores. The present LBM model comes with the careful consideration of the local Knudsen number, local pressure gradient, viscosity correction model, and regularization procedure to account for the rarefied gas flows in irregular pores. Its validity and accuracy are verified by several benchmarking cases, and the calculated results by this boundary scheme accord well with our analytical *** boundary scheme shows a higher accuracy than the existing studies. Additionally, a subiteration strategy is presented to tackle the coupled micro-gaseous flow and surface diffusion, which necessitates the iteration process matching of these two mechanisms. The multi-mechanism flow in the self-developed irregular pores is also numerically investigated and analyzed over a wide range of parameters. The results indicate that the present model can effectively capture the coupling effect of micro-gaseous flow and surface diffusion in a tree-like porous medium.