多孔介质中泡沫微观运移机理及数学模型

Foam flooding can effectively reduce water cut and enhance oil recovery for high water cut and high recovery reservoir, so it is important to relieve the shortage of oil and ensure the energy security in China. Foam is a kind of dispersion fluid in formation, which is greatly influenced by the porous structure, so the flowing parameters from the lab experiments can't accurately describe the foam's flowing state in the formation condition. However, there is less result about the mechanics and law of foam flowing in porous media. Aiming at the flowing mechanics description and state representation in porous medium, this project will use the interface mechanics and fluid mechanics theory, and also combine with micro and medium-levels foam displacement experiment, analysis the flowing state of foam in pore throat model, and then establish flowing constitutive equations of different surface tension foam in different size level pores and throats during different percolation period, and characterize percolation resistance of foam in porous medium. On the above basis, considering the dispersibility and unstability of foam, we will use indicator random simulation method to calculate parameters of foam flow state and mechanics in pore and throat network model, and build the dynamic stochastic model which describes the flowing behaviors of foam in porous medium. By introducing mechanical constitutive equation which reflects foam migration process, and optimizing the percolation theory algorithm, we will establish a percolation mathematical model which describes foam percolation in pore network, and research corresponding solving method and calculation module. In conclusion, this project has great significance for development of physical and chemical percolation theory and foam flooding reservoir simulation method.

泡沫驱能够有效降低双高油藏含水率，大幅度提高采收率，对弥补我国石油短缺具有重要意义。地层中泡沫为分散性流体，受孔隙结构影响较大，室内实验得到的流动参数很难准确代表地层渗流条件下泡沫的流动状态，而目前地层中泡沫流动规律认识较少。本项目针对泡沫在多孔介质中微观力学描述和流动状态表征问题，以界面力学和流体力学为基础，结合泡沫微观和中观驱替实验，对气泡在孔喉模型中流动进行力学分析，建立不同表面张力气泡在不同尺寸喉道、不同流动阶段的力学本构方程。在此基础上，针对泡沫分散性和不稳定性，利用指示随机模拟方法计算气泡在孔喉网络模型中的有效气泡存在概率和流动状态等参数，形成表征气泡流动行为的孔喉网络随机模型。引入泡沫力学本构方程，优化微观网络模型逾渗算法，表征各个孔喉网络节点渗流阻力，建立泡沫驱孔隙网络渗流数学模型，并研制求解方法和模块。本研究对发展物理化学渗流基础理论和泡沫驱数值模拟方法具有指导意义。

泡沫驱能够有效降低双高油藏含水率，大幅度提高采收率。地层中泡沫为分散性流体，宏观流动参数很难准确代表地层渗流条件下泡沫的流动状态，泡沫微观流动规律认识较少。本项目针对泡沫在多孔介质中微观力学描述和流动状态表征问题，通过物理模拟实验、理论推导、编程计算以及数值模拟方法，开展了泡沫在微观孔喉中的流动机理研究，分析了不同表面张力泡沫在无油和遇油条件下的驱油机理和稳定性；考虑泡沫表面张力和孔喉大小，利用水平集方法建立了泡沫在单个孔喉中的运移的数学模型，表征了泡沫在通过孔喉过程中流动规律；基于孔喉网络模型，建立了泡沫在非均质孔喉中流动数学模型，分析了不同表面张力泡沫在不同孔喉结构中的封堵性能；在此基础上进一步设计了高强度泡沫+超低界面张力泡沫交替注入的提高采收率方式，并通过物理模拟实验进行了验证。本项目成果发表论文7篇，授权专利2项，参加会议交流2次。研究成果拓展了泡沫在多孔介质中流动的研究方法，发展和完善了泡沫微观渗流理论。