Oil & Gas Geology ›› 2005, Vol. 26 ›› Issue (4): 444-449.doi: 10.11743/ogg20050408

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Forecasting model of solubility of CH4,CO2 and N2 in crude oil

Xue Haitao1, Lu Shuangfang1, Fu Xiaotai2   

  1. 1. Daqing Petroleum Institute, Daqing, Heilongjiang;
    2. Chongqing Medicine Industry Institute, Chongqing
  • Received:2005-08-01 Online:2005-08-25 Published:2012-01-16

Abstract:

Dissolution characteristics and mechanisms of CH4,CO2 and N2 in crude oil are studied through solubility experiments,resulting in the following understandings: ① hydrocarbons play a key role in the process of gas dissolution in crude oil,while macromolecular substances,such as colloid and asphaltene,have a little influences on the gas solubility.② Gas molecules and macromolecular substances in crude oil can form adduct molecules;this process can be treated as an apparent chemical reaction and its reaction degree can be described by an equilibrium constant K.③ Early formed gas-hydrocarbon adduct molecules have certain solvency to subsequently formed gas molecules,which can be described by a secondary dissolving coefficient α.④ Physical properties of crude oil can be characterized by the density(ρo) of surface crude oil and the mass fraction(xT) and average molecular weight(MT) of hydrocarbons in crude oil.Combined with other factors that have influences on gas dissolution,the theoretical equation of gas'mole solubility in crude oil and that of gas-oil ratio in crude oil are derived.Comparison with experimental data shows that calculated and measured values have a good consistency.

Key words: Methane, CO2, N2, crude oil, solubility, theoretical model

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