三元复合驱化学反应平衡模型及其应用

针对三元复合驱过程中化学反应的特点及我国油田地层的实际情况 ,通过合理简化 ,在分清主要反应和次要反应的基础上 ,提出了新的化学反应平衡物理模型和数学模型 ,并运用新模型进行了实验室岩心驱替的数值模拟。与国外化学驱软件UTCHEM的计算结果对比 ,该模型的计算速度及稳定性有所提高 ,并有一致或相似的规律。针对我国油田地层水中镁离子含量少的特点 ,利用新模型讨论了地层水中镁离子对化学反应平衡及驱油效果的影响 ,分析了碱耗的原因 ,提出在实际油田数值模拟过程中 ,当镁离子浓度比钙离子浓度低一个或一个以上数量级时 ,可以不考虑镁离子的相关反应 ,这样既能提高运算速度又能保证计算精度。

A New Chemical Reaction Equilibrium Model in Alkaline-Surfactant-Polymer Flood and Its Application

In order to obtain a reliable chemical reaction equilibrium model in alkaline surfactant polymer flood, new physical and mathematied models for chemical reaction equilibrium are presented by justifiable simplifying and destinguishing the main reactions and less important ones with regard to the characteristics of the chemical reactions and the situations of oilfields in China. A program is made to simulate the experimental core flooding. Comparing the results of new model with those of the chemical flooding software UTCHEM, it is revealed that the running time of computation is reduced while the calculating accuracy remains almost the same and the results are more stable. The effects of magnesium ion existing in reservoir fluids on the reaction equilibrium and oil recovery are analyzed. The courses of alkaline consumption resulted from magnesium ion are investigated. The results show that if the concentration of magnesium ion in reservoir fluids is lower by one order than that of calcium ion,magnesium relevant reactions can be neglected in field scale simulation to reduce running time while simulation accuracy is unchangeable.