表面活性剂吸附和聚集对粗糙微纳孔隙中油/水流动影响的分子模拟研究

Due to large surface/volume ratio and surface roughness, fluid flow in micro- and nano-pores is affected dramatically by surfactants adsorption and aggregation. In order to improve the understanding of the mechanism of water/oil displacement by surfactants in rough nanopores, this project intends to study the adsorption of surfactants on rough rock surface, the aggregation in solution and the oil/water flow in nanopore in the presence of surfactants using molecular simulation method. It is planed to explore the microstructure of surfactant/oil adsorption layer (molecular density profile and packing modes, adsorption layer thickness ant its charge density distribution) and its influence on the wettability of the solid-liquid interface. The effect of surfactant micelles on bulk viscosity, fluid/solid boundary roughness and wettability modification will be systematically studied, which is subsequently utilized to clarify the effect of theinterfacial adsorption and micellar aggregation of surfactant on the flow resistance in nanopore and the imbibition behavior of oil displacement. Combining flow resistance, solid-liquid wettability modification process and oil-water interfacial tension to study the imbibition behavior of water flooding, this project is expected to improve the theoretical model of the oil displacement mechanism in the nanopores at molecule-level, which is helpful to provide a theoretical basis for the wettability modification of surfactants and the depressure and increasing injection for EOR in low permeability reservoirs.

微纳孔隙具有超高比表面积，导致表面活性剂的吸附和聚集行为对孔隙中流体流动有显著影响。为了加深表面活性剂对粗糙微纳孔隙中油水驱替过程的微观作用机制的认识，本项目拟通过分子模拟方法对表面活性剂在储层岩石粗糙表面吸附和聚集形态，以及表面活性剂存在条件下微纳孔隙中的油/水流动行为进行研究，阐明表面活性剂和原油组分在粗糙岩石表面吸附层的微观结构（分子密度分布和排列方式、吸附层厚度和电荷密度）及其对固液界面润湿性的影响规律。通过系统地研究表面活性剂胶束对体相粘度、流固边界粗糙度和润湿转变的微观机制和动力学过程，明确表面活性剂界面吸附和体相聚集形态对油水单相流动阻力的影响机制。将流动阻力、固液润湿转变过程和油水界面张力相结合研究水驱油两相渗吸行为，在分子尺度完善孔隙中表面活性剂微观驱油机制的理论模型，为表面活性剂在低渗油藏润湿调控和降压增注的应用策略提供理论依据。

低渗油藏微纳孔隙具有超高比表面积和表面粗糙度，表面活性剂吸附和聚集行为对孔隙中流体流动有显著影响。为了加深表面活性剂对粗糙微纳孔隙中油水驱替过程的微观作用机制的认识，本项目通过分子模拟方法对表面活性剂储层岩石粗糙表面吸附、溶液中聚集形态以及表面活性剂存在条件下微纳孔隙中的油/水流动行为进行研究，阐明了表面活性剂吸附层的微观结构以及岩石表面粗糙度和固有疏水性对固液界面润湿性的影响，以及表面活性剂固液界面吸附和体相胶束聚集形态对残余油驱替行为的影响机制，完善孔隙中表面活性剂微观驱油机制的理论模型，为表面活性剂在低渗油藏润湿调控和降压增注的应用策略提供理论依据。