The study of heterogeneous two‐phase flow around small‐scale heterogeneity in porous sandstone by measured elastic wave velocities and lattice Boltzmann method simulation

Abstract

AbstractTwo‐phase fluid flow is strongly controlled by small‐scale (subcore‐scale) heterogeneity of porous sandstone. We monitor the heterogeneous/anisotropic two‐phase flow (CO2 and water) in porous sandstone and conduct multichannel VP and VP anisotropy measurements under super critical CO2 conditions during CO2 injection (drainage) and water reinjection (imbibition) processes. In drainage, VP shows large reduction (~10%) in all sections of the core sample and changes from the bottom inlet side to upper outlet side. It is considered that VP reduction reflects the CO2 movement in the specimen. The VP anisotropy of the upper two planes indicates clear increase. The results of this experiment indicate the heterogeneous CO2 flow around laminae in porous sandstone and characteristic behavior of these laminae as a barrier for CO2. On the other hand, flow of water is not affected by this barrier. This characteristic CO2 water flow around laminae is observed in the numerical simulation results. This simulation study also indicates that the capillary number is not directly affected on two‐phase fluid flow around small‐scale heterogeneity in porous sandstone. These results suggest that the small‐scale heterogeneity behaves as a CO2 gate and strongly controls CO2 behavior in porous sandstone.