确定CO2最小混相压力的状态方程法

混相压力是确定油藏能否采用混相驱的重要依据,测定混相压力的最好方法是细管实验法,但室内实验法测定费时费力。基于细管实验的结果,结合“混相函数”的概念,提出了一种利用组分分割和组合的方法,即将C1^＋组分分割为几种以后,对利用修正的Redlich—kwong状态方程确定CO2最小混相压力的方法进行了研究和改进,克服了原方法中重组分临界值难以确定的缺点;同时提高了温度对计算结果的敏感性。计算结果与实验结果对比表明,确定的最小混相压力误差小于5％,充分证明该方法的有效性。

A method of state equation for determining minimum miscible pressure of CO2

The misciMe pressure is an important foundation of adopting miscible flooding or not in the reservoir. The best method of miscible pressure determination is slim - tube test, but it takes more time and effort. Based on slim - tube test results and the concept of "miscible function" ,a new method using component segmentation and combination was presented, in which component C7 + was segmented into several components. After that, the method was improved applying modified Redlich - Kwong equation of state to determine CO2 minimum miscible pressure. It overcomes the shortcoming of the original method in which the critical value of heavy components was difficult to determine and it also improves the sensitivity of the calculated results to temperature. The contrast between calculated results and experimental ones indicates that the errors in determined minimum miscible pressure are less than 5% ,and the validity of this method is proved.