Reduced Carbon Dioxide Mobility in Experimental Core Flood Using Surface Coated Silica Nanoparticles as a Foaming Agent

Abstract

Abstract Carbon dioxide (CO2) is the most used solvent in enhanced oil recovery (EOR), as it can have a high displacement efficiency in favorable conditions. Its disadvantages are relatively low sweep efficiencies caused by a viscosity and density that is lower than the fluid it displaces. Surface-coated silica nanoparticles create in-situ CO2 foam, which has a more favorable mobility ratio and therefore better sweep. These nanoparticles can also be used in carbon capture and storage (CCS) applications in injecting CO2 foam into brine aquifers. This paper presents the results of core flood experiments that aimed to study surface coated silica nanoparticles as an in-situ CO2 foaming agent. In these experiments, pressure drop was measured across the core as a whole and in five individual sections. The core was placed vertically, and liquid CO2 was pumped at the top of the core. Surface coated silica nanoparticles suspended in the brine is used in some of the floods and compared to a control flood that had no nanoparticles. In these experiments, pressure drops in nanoparticle cases were a multiple of 5-10 those in the control cases. In addition, total core pressure drops in nanoparticle cases increased as the core got more saturated with CO2, and the increase was observed sequentially in each section as it got invaded by CO2.The mobility of CO2 was reduced by an order of magnitude on average compared to the control. The CO2 moved slower through the core and breakthrough was delayed in the nanoparticle case. The study provides quantitative nanoparticle CO2foam mobility measurements and calculations, compared to those in control cases. Properties calculated from this study can be used to improve both EOR and CCS applications of CO2 flooding by scaling the results to the reservoir scale.