Morphology and Surface Chemistry of Gas-Wetting Nanoparticles and Their Effect on the Liquid Menisci in Porous Media

The transformation of the liquid menisci at pore throats is of great importance for mitigating the liquid-blocking effect of condensate reservoirs. Here, we reported a super gas-wetting peanut-like nanoparticle which can facilitate the liquid menisci to transform from concave shape to convex shape by coating a super gas-wetting adsorption with high surface roughness. The morphology and surface chemistry of gas-wetting nanoparticles were investigated by SEM, AFM, and XPS analysis. The mechanism of surface modification was further explored by TEM; the adsorption layer coated on the nanoparticle surface can be recognized as monolayer absorption. The gas-wetting model is recommended as the combination of the Wenzel model and Cassie–Baxter model, which is in close agreement with the results of AFM and contact-angle measurements. Core flooding visualization was performed to identify the effect of gas-wetting alteration on the transformation of liquid menisci in porous media. Results showed that the addition of gas-wetting nanoparticles could decrease the liquid saturations by inducing the transformation of liquid menisci in the pore throat. Additionally, a unique "amoeba effect" and miscibility effect can synergistically improve the mobility of the oil phase, further enhancing the oil recovery.