Experimental study on CO2-EOR in fractured reservoirs: Influence of fracture density, miscibility and production scheme
Experimental study on CO2-EOR in fractured reservoirs: Influence of fracture density, miscibility and production scheme
复制标题
裂缝性油藏 CO2-EOR 实验研究：裂缝密度、混相性和生产方案的影响
DOI：
10.1016/j.petrol.2018.11.039
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发表时间：
2019-03-01
影响因子：
--
通讯作者：
Chen, Xu
中科院分区：
文献类型：
--
作者：
Ding, Mingchen;Gao, Miao;Chen, Xu
研究了裂缝性油藏中裂缝密度、裂缝性和开采方式对CO2提高采收率的影响。在压裂和未压裂条件下，对不同长度的岩心塞进行了一系列CO2注入实验。结果表明，尽管裂缝的存在显着降低了CO2驱的有效性，但增加裂缝密度显然有利于其采收潜力。CO2连续注入初期，原油的采收机理主要是原油膨胀，随着注入时间的延长，原油的采收机理逐渐转变为轻烃（C5 ~ C30）的提取。首次接触混相驱比多次接触混相驱和非混相驱更有效，在裂缝密度大于5.0条裂缝/m时，首次接触混相驱是可行的，最高采收率可达原始地质储量的68.1%。CO2吞吐是CO2驱后剩余油的有效开采方法。裂缝密度对吞吐性能影响不大，但在裂缝密度较低的情况下，需要更多的周期才能达到最终采收率。多接触混相CO2吞吐是裂缝性油藏提高采收率潜力最大的技术，在CO2驱油试验基础上，可提高采收率86.2%。
The effects of fracture density, miscibility and production scheme on CO2 enhanced oil recovery (EOR) in fractured reservoirs were investigated. A series of CO2 injection experiments were performed in various lengths of core plugs at both fractured and unfractured condition. Results demonstrate that although presence of fractures dramatically reduces the effectiveness of CO2 flooding, increasing fracture density clearly benefits its recovery potential. The oil recovery mechanism is mainly recognized to be oil swelling at the beginning of CO2 continuous injection and gradually turns to extraction of lighter hydrocarbons (C-5-C-30) with increased injection time. First-contact miscible flooding is more effective than both multi-contact miscible and immiscible flooding and proves its feasibility when fracture density exceeded 5.0 fractures per meter, with the maximum recovery up to 68.1% of original oil in place (OOIP). CO2 huff-n-puff is very powerful in recovering the residual oil after CO2 flooding. Fracture density has no major effect on huff-n-puff performance while at lower fracture-density condition, more cycles are required to reach the ultimate oil recovery. Multi-contact miscible CO2 huff-n-puff has the greatest potential of EOR ability in fractured reservoirs, which can increase the oil recovery to 86.2% OOIP on the basis of CO2 flooding test.