注气混相驱完整p-X相图模拟计算研究

为了对状态方程的适应性进行评价,以获得油气体系在临界区和两相区的相态特性。通过对油气烃类体系相平衡热力学理论模型的分析,建立了以摩尔质量等比关系和以体积等比关系为基础的注气过程油气烃类体系完整p—X(压力—组成)相图的模拟计算方法,并结合实验数据可以模拟计算出不同注入溶剂(富气、干气、N₂、CO₂)的注气过程烃类体系完整p—X相图。计算结果表明,所建立的方法可靠,能很好地描述烃类体系的相态特征。这对于进一步运用相图确定原油与注入溶剂形成混相的条件及混相机理具有重要的应用意义。

STUDY ON THE SIMULATION CALCULATION OF COMPLETE p-X PHASE DIAGRAM IN MISCIBLE GAS INJECTION

The purpose of this paper is to set up a strict method for complete phase diagram calculations in oil-gas systems and evaluate the adaptability of equation-of-state (EOS) so that the phase characteristics in critical and two phase regions are obtained. Based on the analysis of phase equilibrium thermodynamic model in the hydrocarbon system, the complete pressure-composition (p-X) phase diagram calculation method has been discussed and set up in gas injection process, which is displayed in geometric proportion of molar mass and volume. Applying the theory in conjunction with experimental data, two kinds of displays of the complete p-X phase diagrams are cal-culated in various miscible gases (rich gas, dry gas, N₂, CO₂) injection processes. Results show that the solution prepared here is reliable and can describe phase properties well. It has practical significance for the further determination of miscible conditions and mechanisms of oil and injected solvent by the phase diagram.