Zhang Jianzhong, Gao Shusheng, Xiong Wei, Ye Liyou, Liu Huaxun, Zhu Wenqing, An Weiguo, Han Donghuan, Lin Baicen
University of Chinese Academy of Sciences, Beijing, 101408, China.
Institute of Porous Flow & Fluid Mechanics, Chinese Academy of Sciences, Langfang, 065007, China.
Heliyon. 2024 Oct 10;10(20):e39179. doi: 10.1016/j.heliyon.2024.e39179. eCollection 2024 Oct 30.
The pore throat size, structure distribution, and lithology of porous media in gas reservoirs are varied, and the gas-water two-phase seepage law is complex, making it difficult to describe the seepage model. Newton's law of motion is a basic law of motion in classical mechanics, and its application in gas-water two-phase seepage modeling is an innovative practice of classical mechanics in seepage mechanics systems. Based on Newton's three laws of motion, a gas-water two-phase seepage model was established from the force analysis of fluid, and the relationship between velocity and pressure difference, pipe radius, water film thickness, viscosity, etc. was derived under the condition that the model reached a stable state, i.e., force balance. The relationship is referred to as the steady-state model. Subsequently. the equivalent permeability representation model was derived based on the steady-state model to calculate the permeability of rock samples with different channel distribution characteristics. The results were consistent with the measured values, and there is a good correspondence between channel distribution characteristics and permeability. The relative permeability calculation method was established based on the steady-state model and capillary pressure curve. The obtained relative permeability curve aligned with the two-phase seepage law and coincides with the relative permeability curve obtained by Poiseuille's law. Finally, a new productivity equation was derived based on the steady-state model, and the Inflow Performance Relationship (IPR) curve calculated by the gas well example was consistent with the traditional equation. The research results were based on the force analysis of fluid in porous media and fundamentally explored the law of fluid flow. The derived seepage model can be used to calculate reservoir permeability, the gas-water relative permeability curve, and gas well productivity analysis and to effectively guide gas reservoir development. The study was a successful application of the basic theory of mechanics in gas-water two-phase seepage in gas reservoirs.
气藏多孔介质的孔隙喉道大小、结构分布和岩性各不相同，气水两相渗流规律复杂，难以描述渗流模型。牛顿运动定律是经典力学中的基本运动定律，将其应用于气水两相渗流建模是经典力学在渗流力学体系中的一种创新实践。基于牛顿运动三定律，从流体的受力分析出发建立了气水两相渗流模型，并在模型达到稳态即力平衡的条件下，推导了流速与压差、管径、水膜厚度、黏度等之间的关系。该关系被称为稳态模型。随后，基于稳态模型推导了等效渗透率表征模型，用于计算具有不同通道分布特征的岩样渗透率。结果与测量值一致，通道分布特征与渗透率之间具有良好的对应关系。基于稳态模型和毛细管压力曲线建立了相对渗透率计算方法。得到的相对渗透率曲线符合两相渗流规律，与泊肃叶定律得到的相对渗透率曲线吻合。最后，基于稳态模型推导了新的产能方程，通过气井实例计算得到的流入动态关系（IPR）曲线与传统方程一致。研究成果基于对多孔介质中流体的受力分析，从根本上探索了流体流动规律。所推导的渗流模型可用于计算储层渗透率、气水相对渗透率曲线和气井产能分析，有效指导气藏开发。该研究是力学基础理论在气藏气水两相渗流中的成功应用。
