油水乳状液流场压降与剪切能的关联及其对化学破乳机制的影响

油田开发过程中，原油大部分以各种不同稳定程度的乳化液形式采出，且其采输系统本身的动态性决定了各类不同剪切流场的存在，所带来这些外部剪切作用直接影响着油水乳化液体系在形成及破坏过程中的热力学与动力学稳定性。本项目基于对原油/水两相体系在近井地带地层孔隙和射孔井眼、垂直油管、井口油嘴及集输管道内的剪切历史分析，拟引入剪切能来定量描述其宏观流动压降对剪切作用的贡献，建立不同节点区域油水乳状液流场压降与剪切能的关系模型；通过模拟实验，辨识考虑两相流动过程中剪切能变化的油水乳化行为，研究剪切能差异对化学破乳效能的影响，多尺度解释破乳剂在不同剪切流场中油水界面的作用机制，进而运用剪切能分析并构建原油采输过程中化学破乳剂选择及注入节点优化的方法体系，拓展原油化学破乳技术应用与发展的理论基础，同时进一步丰富油田开发地下地面一体化的理论方法。

During oilfield development, crude oil is mainly produced as emulsion with different stability degrees, and the existence of various shear flow fields is determined by the dynamics of petroleum production system. These external shearing actions directly affect the thermodynamics and dynamics stability of oil-water emulsion system in the process of its formation and destruction. In chemical demulsification, selection of the best injection points during oilfield practices still remains a very challenging task for both operators and chemical vendors. In the gathering & transportation of oil-water emulsion, product of shearing force, shearing area and distance of the flow will constitute the shear work. .Therefore, shearing energy is introduced in this project, the energy responsible for dispersion of one phase of the liquid into the other as the fluid flows through the pipe is dependent on the turbulence available in the pipe. In the flow field, with the constant conditions such as oil-water emulsion system property, temperature and aging time, shearing action will be the dominant factor of oil-water emulsion formation, emulsifying degree and emulsion stability. So, the emulsion point is the area with high shearing energy. Alternatively, in the process of demulsification of petroleum production system, the strong turbulent point with high shearing energy is also the area where chemical demulsifier mixed most sufficient, due to the turbulence and shear will accelerate the chemical demulsifier molecule diffusion and adsorption on the oil-water interface and increase the times and intensity of impact effect among water droplets. Based on the analysis of shear history of oil-water two-phase system in formation pores, wellbore perforations, tubings, christmastrees and surface flowlines, relational model of oil-water emulsion flow field pressure drop and shearing energy in different points is established, using shearing energy to quantitatively describe the contribution of macroscopic flow pressure drop on shearing action. According to the simulation experiments, oil-water emulsion behavior of the shearing energy variation in two-phase flow is identified, effect of different shearing energy on chemical demulsification efficiency is studied and action mechanism of demulsifier in oil-water interface of different shear flow fields is explained. Then the shearing energy is used to analyze and establish the method system of chemical demulsifier option and injection points optimization during petroleum production..Determination of injection points could combat lots of operational and economical problems such as over-treating and re-emulsification. Unnecessary high budgets for demulsifier chemicals will be reduced in field, theoretical basis of crude oil chemical demulsification technology application and development will be extended. In the meanwhile, the surface and subsurface integrated approach in oilfield development will be further improved.