考虑气–水–固相互作用的页岩基质表观渗透率模型

Apparent Permeability Model of Shale Matrix Considering the Interaction of Gas-Water-Solid Phases

摘要: 微纳米页岩基质孔内气水关系复杂，现有的页岩气表观渗透率模型通常只考虑单相气，且存在作用机理考虑不全面、模型构建方法不准确等问题，导致不能合理地揭示页岩基质传质规律。本文基于基质孔中气–水–固三者之间相互作用，建立了考虑页岩气吸附、应力敏感效应、基质收缩效应和束缚水饱和度等多种因素共同影响下的页岩气表观渗透率模型，进行了基质孔表观渗透率敏感性参数分析。结果表明：基质孔表观渗透率与应力敏感系数和束缚水饱和度呈负相关；表面扩散贡献率与压力和孔径呈负相关关系；黏性流贡献率与压力和孔径呈正相关关系。

Abstract: The gas-water relationships within micro-nano shale matrix pores are complex. Existing apparent permeability models for shale gas typically only consider single-phase gas flow, and suffer from issues such as incomplete consideration of interaction mechanisms and inaccurate model construction methods, which hinder their ability to reasonably reveal the mass transfer laws in shale matrix. This study establishes an apparent permeability model for shale gas that accounts for the combined effects of stress-sensitive effects, matrix shrinkage effects, and irreducible water saturation, based on the interactions among gas-water-solid phases in matrix pores. A sensitivity analysis of parameters affecting the apparent permeability of matrix pores is conducted. The results show that the apparent permeability of matrix pores is negatively correlated with both the stress-sensitive coefficient and irreducible water saturation. The contribution rate of surface diffusion exhibits a negative correlation with pressure and pore size, while the contribution rate of viscous flow shows a positive correlation with pressure and pore size.