N2与CH4对CO2非混相驱油效果的影响

在矿场应用中,注入CO2中混有的杂质气体会影响其驱油效果.为制定更加合理有效的开发方案,有必要研究杂质气体对CO2驱的影响.利用油藏数值模拟方法,在纯CO2气体注入参数优化的基础上,研究了N2与CH4两种杂质气体对CO2非混相驱体积波及系数、驱油效率、油井见气时间和采收率的影响;以尽量提高原油采收率为目标,确定了注入气中杂质气体的临界含量.结果表明,杂质气体的存在会导致CO2非混相驱体积波及系数增大,驱油效率降低,油井见气时间缩短;注入的CO2中N2的摩尔分数最高不应超过5%,CH4的摩尔分数最高不应超过14%.

Influence of N2 and CH4 on CO2 immiscible flooding effect

In practical field application, impurities contained in the injected CO2 will impact the flooding efficiency in different levels. In order to design more reasonable and effective de- velopment program, it is necessary to conduct study on the influence of impurities on CO2 flooding. Based on the injection parameter optimization of pure CO2, the influence of N2 and CH4 on CO2 immiscible flooding, including volumetric sweep efficiency, oil displacement ef- ficiency, gas breakthrough time and oil recovery is studied with reservoir numerical simula tion method. Besides, the critical content of impurities contained in injected CO2 is deter- mined aiming to obtain as high recovery as possible. It is shown that the impurities can en- large the volumetric sweep efficiency, lower oil displacement efficiency and shorten the time it needs for injected gas to reach the production wells. The critical content of N2 in injected gas is 5%, while the critical content of CH4 is 14%.