基于微纳米尺度液滴间相互作用的油水乳化分散理论研究

Low quality crude oil is widely existed in China’s inland, boundary and offshore oilfields, which is over 80% of total output. Due to a relatively high percentage of non-hydrocarbon compounds, this crude oil tends to emulsify with water and form a complex oil-water dispersion system, especially under the subsea condition where the temperature is low and heat transfer is severe. It is threatening the safety and efficiency operation of the submarine pipeline. Aimed at revealing the nature of drop interaction in oil-water dispersion, the mesoscopic characteristics of the complex oil-water two phase flow field are investigated from two aspects, one is the fluctuation of oil-water interface and drop rupture, the other is drop collision and coalescence, while both considering the effect of surface active species to indicate the rule of oil-water two phase flow field and drop interaction. The influence of mobility of oil-water interface and interface rheology is considered to obtain the microcosmic mechanism of interaction force between emulsified drops in dispersion. Quantitive description between surfactant interfacial concentration and interfacial mobility is established, where a new method is derived to represent the drop deformation, film evolution and interaction force. Therefore, a new Population Balanced Equations for the micro-structure of crude oil-water dispersion is systematically founded. Based on the above understanding, a further target is explored through controlling the interaction between micro-sized drops, which can help to improve the micro-structure and flow characteristic of crude oil-water two phases.

我国石油资源中低品质原油约占总量的80%，这类原油中非烃类化合物含量较高，伴随海底低温、强换热的自然条件，使得在开采和输送中极易与伴生水形成复杂的油水乳化分散体系，严重影响海底管道的输送安全和高效运行。本项目抓住油水乳化分散微结构中液滴间相互作用的本质，研究流场与界面波动及液滴破裂、液滴碰撞及液滴聚并两方面的相互影响，掌握流场中液滴相互作用的细观规律；查明界面移动、界面流变对液滴间相互作用的影响，从微观层面揭示原油中表面活性物质影响的液滴间相互作用力学机理；由此构建表面活性物质界面浓度同界面移动的定量描述，形成表征微纳米尺度液滴形变、液膜衍化、液滴间作用力的新方法；系统建立适合原油水分散体系微结构表征的群平衡理论新模型；进一步探索调控微观液滴间相互作用的方法，实现改善油水微结构及复杂流动特性的目标。

本课题从微纳尺度液滴间相互作用、液滴形变及界面行为出发，开展了液滴间微观力学作用的研究，揭示了分散体系中液滴间相互作用的力学机理，建立了表征液滴间动态作用、液滴形变及液膜衍化表征方法，实现了对微观层面液滴间力学作用的探究和分析。同时，通过研究界面活性物质影响下的液滴破裂、碰撞及聚并机制，对油水界面波动及液滴破裂、聚并的细观流场特征进行了表征，揭示了油水两相流场与液滴间相互作用的细观机理，进一步完善了油水分散体系微结构表征方法。结果表明界面活性物质影响着分散相液滴间的相互作用，从而影响液滴破裂、聚并过程，并体现在油水体系流动特性的差异上。本课题形成了衔接微观、细观及表观层面的油水多相体系乳化分散机理，为通过调控液滴间相互作用实现改善油水分散体系的流动特性提供思路，为解答多相复杂流动的油水乳化及破乳机制、油水高效输送等技术难题提供理论依据。