高温高压气体－原油分子扩散系数研究

分子扩散在注气开发过程中有重要作用，是影响气-液混相效果的重要参数。目前通用的相态计算软件在计算过程中均假设油气一接触就立刻达到平衡，由于扩散影响，实际上这种现象是不存在的。采用定容扩散方法及相关模型研究了高浓度CO₂、CH₄、N₂体系与油田地面分离器原油之间的扩散现象，研究表明：气－油体系并不是一接触立刻达到平衡，与组分的扩散速度有关；扩散系数为一变化值，随着压力的降低，扩散系数逐渐增加，直至体系达到平衡；而且在实验过程中发现不同位置液相的性质不同。实验研究为相态研究开辟了一条新的道路，所取得的成果对优化注气方案有一定的参考价值。

MOLECULAR DIFFUSION COEFFICIENT OF GASOIL SYSTEM UNDER THE CONDITION OF HIGH TEMPERATURE AND PRESSURE

The molecular diffusion is an important factor to affect mass transfer phenomenon during a gas injection process.It is one of key parameters to determine the miscibility effectiveness of injected gas and oil system.Most of current commercial reservoir simulators for the phase behavior calculation are only based on the assumption that oil and injected gas system reaches equilibrium immediately once they contact each other.There is no diffusion phenomenon occurring between the two phases.Authors of this paper present the constant volume diffusion research for the fluid system which is of high concentration of CO₂，CH₄，N₂ and the crude oil from surface separator.The study is to aim at the investigation of diffusing mechanism between oil and injected gas under the condition of high temperature and pressure.The results show that the oil and gas do not reach balance while contacting，it is related to the component diffusion velocity.The diffusion coefficient is not a constant，it increases as pressure decreases.Once the system reaches equilibrium，the diffusion coefficient will not change.The liquid properties are not the same because of different position.This research provides a new approach for phase study and valuable information for optimizing the gas injection process.