Influence of nanoparticles on CO2 transport characteristics in water alternating gas injection process

In order to effectively control CO2 EOR and the fluidity of CO2 fluid in CO2 storage process, the nanoparticles are injected into reservoir or sandstone aquifer. In the indoor test, a CT scanner is used to observe and measure the flow pattern and saturation of fluid in the displacement of brine/nanoparticle solution by CO2 as well as in the displacement of CO2 by brine/nanoparticle solution. The research indicates that, in the nanoparticle solution test, the CO2 displacement fronts are relatively consistent, the flow velocity of fluid is relatively low, and the initial CO2 saturation and residual CO2 saturation are higher than those in brine test. The nanoparticles drive CO2 and brine to form the stable emulsion, reduce the fluidity of fluid, and increase the effective viscosity of fluid. According to the Land Equation, the constant C is 2.45 in brine test and is 2.25 in nanoparticle test. Therefore the constant C should be as less as possible during the formulation of the plan of CO2 injection, so as to slow down the viscosity fingering during the alternate injection of gas and water, and retain or store more CO2 in stratum.