多元气-液-固复杂体系相平衡

石油流体中含有气相、液相及可能遇到的固相包括水合物、石蜡和沥青质等,涉及多元气-液-固复杂体系的相平衡问题.为防止这些沉积物堵塞造成安全隐患,需要确定水合物、石蜡、沥青质沉积起始条件以及沉积量.本文针对化学热力学理论在含水合物、石蜡和沥青质的多元-多相平衡研究中的应用进行了综述.水合物相平衡模型较为成熟,主要有两类,其一为基于等温吸附理论的van der Waals-Platteeuw型热力学模型;其二为基于双过程水合物生成机理的Chen-Guo水合物热力学模型.石蜡沉积一般采用活度系数法、状态方程法及多固相模型描述.沥青质絮凝、沉积则可采用溶解度参数模型、状态方程法、胶体模型和标度理论模型进行计算.同时对多元气-液-固复杂体系的相平衡研究发展方向进行了展望.

A review on the modeling of gas-liquids-solids multi-phase equilibrium in complex petroleum systems

In the exploitation,transportation and process of oil and natural gas,there exists gas phase,liquid phases,and potential solid phases,including gas hydrate,paraffin,and asphaltene.Solid precipitations such as gas hydrate,paraffin,and asphaltene in gas and oil exploitation/transportation facilities and pipelines are undesirable since it may plug them and bring safety problem.To avoid solid aggregation in petroleum fluid,it is necessary to determine the onset and the amount of precipitation of these solids,which concerning a complex gas-liquids-solids multi-phase equilibrium issue.This paper reviews the application of chemical thermodynamics theories in the modeling of gas-liquids-solids multi-phase equilibrium in complex petroleum systems.The modeling of gas hydrate phase equilibrium has been well developed,which is divided into two categories,i.e.van der Waals and Platteeuw （vdWP） type models based on isothermal adsorption theory,and Chen and Guo type models based on reaction-adsorption two-step formation mechanism.The paraffin precipitation is usually described by activity coefficient model,equation of state,or multisolid-phase model.The onset and amount of asphaltene precipitation could be calculated using solubility parameter model,equation of state,micellization model,or scaling equation.The important aspects for future gas-liquids-solids multi-phase equilibrium research were discussed.