Estimating effective rates of convective mixing from commercial-scale injection

In this work, the ongoing CO2 injection at the Utsira formation is considered as a field-scale study for CO2 storage. We employ an upscaled model for CO2 migration that in addition to the standard two-phase flow physics includes dissolution, effective convective mixing and capillary trapping. The aim of this work is to get the first field-scale estimates of the effective upscaled convective mixing rates. To account for the uncertainties in the description of the storage formation, sensitivity studies are conducted relative to some of the most uncertain parameters. This paper thus presents the first field-scale estimates of upscaled convective mixing in the context of CO2 storage. Our result gives upscaled convective mixing rates in the order of 15 kg/m(2)/year. These numbers are comparable, but somewhat higher than previous analysis using high-resolution numerical simulations would indicate. As such, our work validates the use of numerical simulations to obtain upscaled convective mixing rates, while at the same time yielding validation of convective mixing as an important and quantifiable storage mechanism in the Utsira formation.