Apparent permeability in tight gas reservoirs combining rarefied gas flow in a microtube

Frontiers in Earth Science

Earth Science

Jiahuan He¹  Tao Li¹  Yongming Li²  Wenlian Xiao²  Lingli Zheng²  Muyao Chen² 

[1] Exploration and Development Research Institute, PetroChina Southwest Oil and Gasfield Company, Chengdu, China;State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu, China;

关键词: microtube;    apparent permeability model;    slippage effect;    Knudsen diffusion;    tight gas;   

DOI  :  10.3389/feart.2023.1132882

 received in 2022-12-28, accepted in 2023-02-17,  发布年份 2023

来源: Frontiers

【 摘 要 】

In tight gas reservoirs, the major flow channels are composed of micro/nanopores in which the rarefaction effect is prominent and the traditional Darcy law is not appropriate for gas flow. By combining the Maxwell first-order slip boundary condition and Navier–Stokes equations, a three-dimensional (3D) analysis of compressible gas slip flow in a microtube was presented, and the flux rate and pressure variation in the flow direction were discussed. Subsequently, by superimposing the Knudsen diffusion, a gas flux formula applicable to a larger Knudsen number was further proposed and satisfactorily verified by two groups of published experimental data in microtubes or microchannels in the membrane. The results indicate that slip flow and Knudsen diffusion make an important contribution to the total gas flow in the microtube, and their weight increases with an increase in the Knudsen number. By substituting the gas flux formula into Darcy’s law for compressible gas, a new apparent permeability model for tight gas reservoirs was proposed, in which the slippage effect and Knudsen diffusion were synthetically considered. The results indicate that the apparent permeability of tight reservoirs strongly depends on the reservoir pressure and pore-throat radius, and an underestimation value may be predicted by the previously published models. This study provides a case study for evaluating these apparent permeability models, which remains a challenging task in the laboratory.

【 授权许可】

Unknown   
Copyright © 2023 Zheng, Chen, Li, He, Li and Xiao.