Recently, polymer thickeners have been considered for CO₂ mobility control during enhanced oil recovery (EOR) processes. Despite that, the requirement of co‐solvents is a controversial challenge for the solution of high‐molecular weight thickeners in gases. This study is focused on small molecule thickeners for carbon dioxide EOR without adding co‐solvents. Polydimethylsiloxane (PDMS) was used as a CO₂‐philic thickener in different low molecular weights. Cloud‐point pressure, relative viscosity, and interfacial tension (IFT) between intermediate crude oil and pure/thickened CO₂ were measured at reservoir conditions. Also, the impact of PDMS‐CO₂ thickener on gas mobility control was evaluated during the coreflooding experiments in secondary and tertiary modes. The experimental results show that PDMS caused an increase in relative viscosity up to 4.7‐fold and successfully thickened CO₂. In addition, the minimum miscibility pressure of PDMS‐thickened CO₂ was lower than that of pure CO₂, and miscible PDMS‐CO₂ thickener occurred at higher PDMS molecular weights. However, the gas breakthrough time can be considerably delayed if the PDMS‐thickened CO₂ was flooded directly, which increased the oil recovery factor between 6% to 15% during tertiary recovery.

中文翻译：

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在二次和三次采油过程中，通过小分子增稠剂控制CO2的迁移率

最近，已经考虑在增油采收（EOR）过程中将聚合物增稠剂用于CO ₂迁移率控制。尽管如此，对于高分子量增稠剂在气体中的解决方案，共溶剂的要求还是一个有争议的挑战。这项研究的重点是在不添加助溶剂的情况下实现二氧化碳EOR的小分子增稠剂。聚二甲基硅氧烷（PDMS）被用作不同分子量的亲CO ₂增稠剂。在储层条件下测量了中间原油和纯/增稠的CO ₂之间的浊点压力，相对粘度和界面张力（IFT）。另外，PDMS‐CO ₂的影响在二次和三次模式下的岩心驱替实验中评估了增稠剂对气体迁移率的控制作用。实验结果表明，PDMS导致相对粘度增加了4.7倍，并成功使CO ₂增稠。此外，PDMS增稠的CO ₂的最小可混溶压力低于纯CO ₂的最小可混溶压力，而PDMS分子量较高时会发生可混溶的PDMS-CO ₂增稠剂。但是，如果直接注入PDMS增稠的CO ₂，则气体穿透时间会大大延迟，这会在三次采油过程中将采油率提高6％至15％。