CO_2驱最小混相压力的测定与预测

Determination and prediction of minimum miscibility pressure in CO_2 flooding

在细管驱替实验数据的基础上,对确定CO2驱最小混相压力的各种方法进行了评价。对于细管驱替实验,混相条件的判断标准应该是采收率随驱替压力变化曲线上的拐点,而不是高的采收率。经验关联式计算最小混相压力简单、方便,但可靠性较差,且对于高温、高CH4和N2含量、高气油比等比较特殊的原油,须进一步增加关联参数。状态方程能较准确快速地计算最小混相压力,但对混相函数值难以给出一个实用的判断标准,计算时应根据泡点压力变化、温度、CO2浓度和混相函数值综合确定体系的最小混相压力。综合研究对比表明,细管驱替实验仍是最准确的、不可替代的确定最小混相压力的方法。

Various method to determine the minimum miscibility pressure (MMP) of CO2 flooding was evaluated on the basis of slime-tube displacement test data. For the slime-tube displacement test, The diagnostic criterion of miscible conditions is the flex point on the changing curve of oil recovery with displacement pressure, but not the high oil recovery. Experience correlations were simple and convenient to predict the MMP, but they arenot reliable and not applicable to more special crude with high temperature, high content of CH4 & N4 and high gas-oil ratio, and need further to increase correlation parameters. State equation can determine the MMP more quickly and exactly, but it was difficult to give a diagnostic criterion for the miscible function value. The MMP of the system should be determined according to the bubble point pressure variation, temperature, CO2 concentration and miscible function value during calculation. Comprehensive research correlation presented that the slime-tube displacement test was still the most exact and non-substitutable method of determining the MMP.