Chen Shaojie, Zhang Jicheng, Mohammed M Zaki, Li Faxin, Yan Zhikai, Ding Yi Song
College of Energy and Mining Engineering, Shandong University of Science and Technology, Qingdao 266590, China.
Faculty of Engineering, Al-Azhar University, Cairo 11884, Egypt.
ACS Omega. 2022 Aug 17;7(34):30104-30112. doi: 10.1021/acsomega.2c03143. eCollection 2022 Aug 30.
Clarifying the microscale gas-water flow behaviors in a mixed wettability reservoir is of great importance for underground engineering. A numerical model of mixed wettability based on circular particles was constructed using the MATLAB stochastic distribution program, and the gas-water flow was simulated based on the phase-field method. The Navier-Stokes equations were solved by the finite element method. The work analyzed the effects of the content of heterogeneous wetting particles, wettability, and inversed wettability of the matrix on the flow path and pressure distribution of the mixed wettability model. Besides, the two-phase flow behaviors were evaluated in microscale mixed-wettability porous media. The simulation results revealed that (i) the residual saturation of the gas phase showed a positive correlation with the hydrophobic particle content, and closed gases only existed in isolated pore channels with small content. Isolated closed gases gradually connected as the content increased. (ii) The residual gas content in the corner and tail end increased as the hydrophobicity of particles increased in hydrophilic matrices. Hydrophobic matrices showed a negative correlation, with the greatest pressure drop due to capillary resistance and step changes in the neutral-hydrophobic transition zone. (iii) Water-phase breakthrough time and gas-phase residual saturation showed a negative correlation change. The more space occupied by the gas phase, the faster the water-phase breakthrough. Moreover, the saturation no longer changes after the breakthrough. The work provides a guideline for determining the dominant flow path of phase displacements and the distribution of residual phases.
阐明混合润湿性油藏中的微观气-水流动行为对地下工程至关重要。利用MATLAB随机分布程序构建了基于圆形颗粒的混合润湿性数值模型，并基于相场法模拟了气-水流动。通过有限元法求解纳维-斯托克斯方程。该工作分析了非均质润湿颗粒含量、润湿性以及基质反润湿性对混合润湿性模型流动路径和压力分布的影响。此外，还对微观混合润湿性多孔介质中的两相流动行为进行了评估。模拟结果表明：（i）气相残余饱和度与疏水颗粒含量呈正相关，封闭气体仅存在于含量较小的孤立孔隙通道中。随着含量增加，孤立的封闭气体逐渐连通。（ii）在亲水性基质中，角落和尾端的残余气体含量随着颗粒疏水性的增加而增加。疏水性基质呈负相关，由于毛细管阻力和中性-疏水过渡区的阶跃变化，压力降最大。（iii）水相突破时间与气相残余饱和度呈负相关变化。气相占据的空间越大，水相突破越快。此外，突破后饱和度不再变化。该工作为确定相驱替的主要流动路径和残余相分布提供了指导。
