Pore-Scale Assessment of Nanoparticle-Stabilized CO2 Foam for Enhanced Oil Recovery

In this paper, we evaluate nanoparticle-stabilized CO2 foam stability and effectiveness in enhanced oil recovery at the pore and micromodel scales. The nanoparticle-stabilized CO2 gas-in-brine foams maintain excellent stability within microconfined media and continue to be stable after 10 days, as compared to less than 1 day for surfactant foam. The nanoparticle-stabilized CO2 foams are shown to generate a 3-fold increase in oil recovery (an additional 15% initial oil in place), as compared to an otherwise similar CO2 gas flood. Fluorescence imaging is applied to quantify emulsion size distribution (down to 1 mu m) in both CO2 and nanoparticle-stabilized CO2 foam flood cases. Nanoparticle-stabilized CO2 foam flooding results in significantly smaller oil-in-water emulsion sizes with an average size of 1.7 mu m (similar to 80% smaller than a CO2 gas flood), with negligible impact on water-in-oil emulsions. The effectiveness of nanoparticle-stabilized CO2 foam is compared for representative light, medium, and heavy oils. All three oils show substantial additional oil recovery and a potentially valuable reservoir homogenization effect. Collectively, these results highlight the pore-scale dynamics, effectiveness, and potential for nanoparticle-stabilized foams in enhanced oil recovery.

在本文中，我们在孔隙和微观模型尺度上评估了纳米颗粒稳定的二氧化碳泡沫的稳定性以及在提高采收率方面的有效性。与表面活性剂泡沫不到1天的稳定性相比，纳米颗粒稳定的二氧化碳盐水包气泡沫在微受限介质中保持了极好的稳定性，并且在10天后仍然稳定。与其他类似的二氧化碳气驱相比，纳米颗粒稳定的二氧化碳泡沫使采收率提高了3倍（额外采出15%的原始地质储量原油）。应用荧光成像来量化二氧化碳驱和纳米颗粒稳定的二氧化碳泡沫驱情况下的乳液尺寸分布（小至1微米）。纳米颗粒稳定的二氧化碳泡沫驱导致水包油乳液尺寸显著变小，平均尺寸为1.7微米（比二氧化碳气驱小约80%），对油包水乳液的影响可忽略不计。比较了纳米颗粒稳定的二氧化碳泡沫对具有代表性的轻质油、中质油和重质油的有效性。这三种油都显示出显著的额外采收率以及潜在的有价值的油藏均质化效果。总体而言，这些结果突出了纳米颗粒稳定泡沫在提高采收率方面的孔隙尺度动力学、有效性和潜力。