Abstract: The heavy organic substances,such as wax,resin and asphaltene will precipitate as a solid phase,causing serioius problems to operate the oil and gas fields,when thermodynamic conditions of temperature,pressure or composition are changed in the process of oil and gas production.A thermodynamic model of the gas-liquid-solid three phases equilibria is presented,combing an equation of state with a solution theory.A regular solution theory is used to account for the non-ideality of the solid mixture,and an equation of state describes both gas and liquid phase behavior.A wax precipitation calculation for a live oil system is conducted using the thermodynamic model.The calculation results demonstrate that the pressure has a greater influence on that wax precipitation.The effect of pressure on wax precipitation temperature is greater below the saturate pressure than the above saturate pressure.

Key words: gas-liquid-solid, wax precipitation, thermodynamic model, equation of state, regular solution

摘要： 在油气开采过程中,当体系的温度、压力或组成等热力学条件发生改变时,油气体系内的蜡质、胶质、沥青质等有机固相物质将会从体系中析出而沉积,给油气田生产带来严重的危害.采用状态方程和溶液理论相结合而建立了能模拟石蜡沉积的气液固三相相平衡热力学模型.根据正规溶液理论描述固相混合物的非理想性,采用状态方程描述气相和液相的相态.运用该模型对某一含气原油进行了蜡固相沉积模拟计算,计算结果表明,压力对蜡沉积有较大的影响,压力对蜡沉积点温度的影响在低于饱和压力下比高于饱和压力下的影响更为显著.

关键词: 气液固, 石蜡沉积, 热力学模型, 状态方程, 正规溶液