Integration of sub- meter scale lithological heterogeneity in reservoir models for an improved quantification of CO2 trapping capacities

Abstract

Sub-meter scale lithological heterogeneity in the form of sedimentary structures such as cross, planar and massive beddings is known to enhance carbon mineral trapping. However, this understanding is largely qualitative. Quantitative estimates of trapping capacities at this scale are limited by the availability of high-resolution field data. Additionally, such heterogeneity is typically not accounted for in conventional reservoir models due to computational restriction posed by the grid size resolution. As a result, the impact of sub-meter scale lithological heterogeneity on carbon trapping capacities is typically not accounted for in dynamic flow and reactive transport simulations at the reservoir scale. The present study aims to quantify the impact of intraformational baffles on carbon mineralization for a range of rock types. A series of 2-D multiphase reactive transport simulations were set-up to model the geochemical processes occurring at the interface of a baffle and a reservoir rock for a period of 1000 years. The study shows that the presence of baffles with certain rock properties within the reservoir rock can enhance or reduce carbon mineral trapping capacity relative to homogeneous reservoir rocks depending on clay and carbonate mineral content in baffles. Further, a new workflow is developed to build a 2D high-resolution reservoir model of the Paaratte Formation, Otway Basin while overcoming the technical challenges associated with sub-meter scale discretization of geological models.