文献类型：期刊文献

英文题名：Recovery mechanism of supercritical CO2 miscible flooding in 30 nm nanomatrices with multi-scale and fracture heterogeneity

作者：Sun, Jiafeng[1];Sun, Linghui[2];Bao, Bo[1]

机构：[1]East China Univ Sci & Technol, Sch Chem Engn, Shanghai 200237, Peoples R China;[2]Petrochina Res Inst Petr Explorat & Dev, State Key Lab Enhanced Oil Recovery, Beijing 100083, Peoples R China

年份：2025

卷号：392

外文期刊名：FUEL

收录：;EI(收录号：20250917947168);WOS:【SCI-EXPANDED(收录号:WOS:001435227800001)】；

基金：This work was financially supported by the National Natural Science Foundation of China (No. 22278128) , the CNPC Major Project (2021ZZ01-03) , and the National Key Research and Development Pro-gram (2023YFF0614100) .

语种：英文

外文关键词：Miscible flooding; Fractured porous media; Nanopores; Phase behavior; CO2 injection

摘要：Carbon dioxide-enhanced oil recovery (CO2-EOR) is a highly promising CO2 utilization and storage technology, with supercritical CO2 (scCO2) miscible flooding being a particularly effective method. However, the lack of a comprehensive understanding of phase behavior and flow dynamics during miscible flooding poses a significant obstacle to the advancement of scCO2 miscible flooding in engineering applications. This study uses nanofluidic chips with a minimum pore depth of 30 nm and a dual-pump experiment platform to simulate the interaction between oil and gas phases in reservoirs. The value of log Ca changes from-5.20 in immiscible flooding to-1.02 in miscible flooding, resulting in a stable and uniform flooding process. The influence of scale on sweeping efficiency is examined, showing a diminishing enhancement effect of miscible flooding as the scale decreases. A comparison of miscible and immiscible flooding reveals a 57.5 % increase in recovery, demonstrating the contribution of the interface vanishing for rapid sweeping. Experiments in different nanomatrices highlight the necessity of fracturing for miscible flooding. The study also explored the effects of diverse injection modes on fluid flow in the nanomatrices, to provide valuable insights and practical recommendations for engineering applications. The results suggest that increasing pressure does not yield proportional returns when using constant-pressure injection. The advantages of in-situ visualization, reliable pressure control, and multiscale nanomatrices highlight the significant value of this research in elucidating the coupling mechanisms underlying phase behavior, porous media structure, and flow dynamics.