The impact of heterogeneity on the distribution of CO 2: Numerical simulation of CO 2 storage at Ketzin

Abstract

Numerical modelling of multiphase flow is an essential tool to ensure the viability of long-term and safe CO 2 storage in geological formations. Uncertainties arising from the heterogeneity of the formation and lack of knowledge of formation properties need to be assessed in order to create a model that can reproduce the data available from monitoring. In this study, we investigated the impact of unknown spatial variability in the petrophysical properties within a sandy channel facies of a fluviatile storage formation using stochastic methods in a Monte Carlo approach. The stochastic method has been applied to the Ketzin test site (CO 2SINK), and demonstrates that the deterministic homogeneous model satisfactorily predicts the first CO 2 arrival time at the Ketzin site. The equivalent permeability was adjusted to the injection pressure and is in good agreement with the hydraulic test. It has been shown that with increasing small-scale heterogeneity, the sharpness of the CO 2 front decreases and a greater volume of the reservoir is affected, which is also seen in an increased amount of dissolved CO 2. Increased anisotropy creates fingering effects, which result in higher probabilities for earlier arrival times. Generally, injectivity decreases with increasing heterogeneity.