二氧化碳驱提高石油采收率数值模拟研究

NUMERICAL SIMULATION STUDY ON ENHANCING RECOVERY FACTOR BY CO_2 DISPLACEMENT

人类大量排放的CO2温室气体使全球气候变暖,其幅度已经超出了地球本身自然变动的范围,对人类的生存和社会经济的发展构成了严重的威胁。CO2的地质处置最有效的方式就是注入油气田,不但封存了二氧化碳,而且还可提高油气田的采收率。针对这一问题,应用Eclipse软件对某油田注入CO2进行水气交替驱等6套开发调整方案进行了数值模拟对比研究。结果表明,该方法可提高石油采收率5%～10%,相当于增加了20亿美元的经济效益;地质储存CO2共计55×104t,相当于一个500万人口的大城市一年排出的温室气体总量,其环境保护的意义是巨大的。研究结果还表明,水平井水气交替驱是地质储存CO2、提高石油采收率的最优方法,该方法累计产油量最大,储集的CO2也最多。这一结论为其他类似油田三次采油提供了技术参考,也可为我国在2012年后执行京都议定书减排CO提供依据。

Huge number of greenhouse gas emission of carbon dioxide(CO2),which leads to global warming,is accelerating the rising temperature and the climate change on the Earth.Global warming has put much pressure on both human being's survival and social economy's development.The most effective way of disposing CO2 is to inject them directly into oil and gas fields,and only in this way not only CO2 can be sealed up for keeping but the recovery factor of oil and gas fields can be enhanced.Aiming at this issue,CO2 was injected into a certain oilfield to carry on water alternating gas displacement by adopting Eclipse software to accomplish correlation study through numerical simulation on six different sets of developing adjustment schemes.This study shows that this method can help improve recovery factor by 5%-10%,equivalent to 2 billion of US dollars,and meanwhile the total CO2 stored in geological way reaches up to 550 thousand tons,having the same quantity of annual greenhouse gas emission from a big city with 5 million people,which also proves its great significance in environment protection.This case of study also shows water alternating gas displacement in horizontal wells is the best way for both storing CO2 in geological way and enhancing recovery factor of oil and gas fields.This method has been proved to have both the maximum accumulative oil production and the greatest number of gathered CO2.This result provides technical reference for the tertiary oil production in other similar oil fields,and the foundation for China's enforcing the obligation of CO2 emission cuts by the Kyoto Protocol in 2012.