Compositional Modeling of Impure CO2 Injection for Enhanced Oil Recovery and CO2 Storage

将二氧化碳(一种温室气体)注入储层中,通过提取剩余油以及在储层中储存二氧化碳在经济上和在环境上是有益的。从各种来源捕获的二氧化碳总是含有各种杂质,这些杂质会影响油藏中的油气系统,改变原油产量和二氧化碳地质储存性能。因此,有必要检查杂质对提高石油采收率(EOR)和碳捕集与封存(CCS)性能的影响。对于加拿大 Weyburn W3 流体,进行了水气交替注入(WAG)的二维成分模拟,以分析不纯CO2对EOR和CCS性能的影响。

CO2流中的大多数组分,如CH4、H2、N2、O2和Ar,会不利地增加油气混合物之间的最小混相压力MMP,而H2S会降低MMP。MMP根据CO2流中杂质的类型和浓度而变化。CO2流中的杂质也降低了波及效率和驱替效率,增加了气体和储层流体之间的界面张力(IFT),并阻碍了原油密度的降低。粘性重数增加59.6%,导致垂向波及效率下降。在碳储存的情况下,与纯CO2的WAG相比,杂质降低了4.1%的束缚空间和5.6%的溶解捕集。结果,CO2 中的杂质使采收率降低了9.2%,CCS总性能降低了4.3%。



Injecting CO2, a greenhouse gas, into the reservoir could be beneficial economically, by extracting remaining oil, and environmentally, by storing CO2 in the reservoir. CO2 captured from various sources always contains various impurities that affect the gas–oil system in the reservoir, changing oil productivity and CO2 geological storage performance. Therefore, it is necessary to examine the effect of impurities on both enhanced oil recovery (EOR) and carbon capture and storage (CCS) performance. For Canada Weyburn W3 fluid, a 2D compositional simulation of water alternating-gas (WAG) injection was conducted to analyze the effect of impure CO2 on EOR and CCS performance.

Most components in the CO2 stream such as CH4, H2, N2, O2, and Ar can unfavorably increase the MMP between the oil and gas mixture, while H2S decreased the MMP. MMP changed according to the type and concentration of impurity in the CO2 stream. Impurities in the CO2 stream also decreased both sweep efficiency and displacement efficiency, increased the IFT between gas and reservoir fluid, and hindered oil density reduction. The viscous gravity number increased by 59.6%, resulting in a decrease in vertical sweep efficiency. In the case of carbon storage, impurities decreased the performance of residual trapping by 4.1% and solubility trapping by 5.6% compared with pure CO2 WAG. As a result, impurities in CO2 reduced oil recovery by 9.2% and total CCS performance by 4.3%.


CCUS; CO2-EOR; carbon capture and storage; CCS-EOR; impure CO2; water alternating gas (WAG)

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