基于LBM-IBM-DEM的微纳米弹性微球微观渗流的耦合模型及数值模拟

In-depth profile control and oil displacement technology using micro/nano elastic microspheres has become a cost-effective enhanced oil recovery method with extensive prospects of application and development at the mid-high water-cut stage of the water flooding oilfields in our country. However, at present, the percolation mechanisms, especially the microscopic percolation mechanisms of this kind of typical solid particles in porous media are not well understood. In the current project, on the basis of the primary research, a new coupled method based on LBM-IBM-DEM (i.e., Lattice Boltzmann method-immersed boundary method-discrete element method) is introduced to further elucidate the microscopic percolation mechanisms of micro/nano elastic microspheres in porous media. First, the properties of micro/nano elastic microspheres will be test and the microscopic flow experiments will be performed, which will provide basic parameters and experiment validation for the microscopic simulation. Then a coupled model for the microscopic percolation of micro/nano elastic microspheres based on LBM-IBM-DEM will be established and used to simulate the transport, deposition, release, capture, plugging and deformation-migration (restart) processes of micro/nano elastic microspheres in porous media. The aim is to build the relationship between the micro-scale flow of micro/nano elastic microspheres and the characteristics of pore-throats and fluid, and finally reveal the fluid-solid coupling nature of micro/nano elastic microspheres percolation in porous media. The research results will lay a theoretical foundation for the industrial application of micro/nano elastic microspheres, and thus promote the basic research for the application of micro/nano polymer materials in enhancing oil recovery.

微纳米弹性微球深部调驱技术已成为我国注水开发油田中高含水期一种经济有效的提高原油采收率方法，具有广阔的应用和发展前景。但目前对这类典型固体颗粒的渗流机理，尤其是微观渗流机制的认识尚不明确。本项目拟在已有研究基础上，引入一种新的基于LBM-IBM-DEM（格子Boltzmann方法-浸入边界法-离散单元法）耦合的方法，进一步阐释微纳米弹性微球的微观渗流机制。通过微纳米弹性微球性能测试及微观渗流实验，为微观模拟提供基础参数和实验验证；建立基于LBM-IBM-DEM的微纳米弹性微球微观渗流耦合模型，对微纳米弹性微球在多孔介质中运移、沉积、释放、捕集、封堵与变形运移（重启动）过程开展数值模拟，建立微纳米弹性微球微尺度流动与孔喉特征、流体性质之间的关系，最终揭示多孔介质中微纳米弹性微球渗流的流固耦合本质，为微纳米弹性微球的工业化应用奠定理论基础，促进高分子微纳米材料在提高原油采收率中的应用基础研究。

微纳米弹性微球深部调驱技术已成为我国注水开发油田中高含水期一种经济有效的提高原油采收率方法，具有广阔的应用和发展前景。微纳米弹性微球在多孔介质中的渗流极其复杂，认识其渗流机制和提高采收率机理是决定其应用前景的关键问题。本研究首先优化合成了微米级、纳米级以及大尺度的系列微纳米弹性微球，对微纳米弹性微球的粒径大小、粘弹特性、蠕变特性等参数进行了测试和分析，并评价了其调驱性能；其次，研究了微纳米弹性微球的运移规律与滞留特性、封堵机理和变形运移机制、调驱机理及启动剩余油机制，并对微纳米弹性微球在多孔介质中运移、滞留、封堵和变形运移过程的微观作用力进行了理论分析和计算；再次，推导了微纳米弹性微球运移的连续性方程，建立了微纳米弹性微球滞留的动力学方程以及微纳米弹性微球滞留引起多孔介质孔隙度、渗透率变化的方程，分析了多孔介质孔隙度和渗透率的变化规律；最后，建立了基于LBM-IBM-DEM的微纳米弹性微球微观渗流的耦合模型及数值模拟方法，基本实现了微纳米弹性微球在多孔介质中运移、封堵和变形过程的动态模拟，进一步阐释多孔介质中微纳米弹性微球的渗流机制。研究成果对于认识多孔介质中微纳米弹性微球的渗流机理具有重要的学术价值，也为微纳米弹性微球的推广应用奠定了良好的理论基础。