Increasing Geological Complexity of a Basin-Scale Model of the Mt. Simon Sandstone for the Simulation of Carbon Sequestration

Abstract

The Cambrian Mt. Simon Sandstone is an appealing target for geologic carbon storage (GCS) research in North America because of its large storage capacity and retention capability. The Midwest Geological Sequestration Consortium has an ongoing effort to simulate commercial-scale GCS within the Mt. Simon of the Illinois Basin. Previous iterations of the static, geocellular model contained simplified, homogenous layers of petrophysical properties based on data from a single location. An updated basin-scale static geocellular model of the formation was developed that would feature lateral heterogeneity within each layer. The motivation for this research was to study the effects of lateral heterogeneity on CO₂ migration and pressure response, which was not examined in previous simulations, as well as generate a model more representative of the regional trends in reservoir architecture interpreted from ongoing research. The revised Mt Simon conceptual model identified controls on petrophysical properties for different zones within the Mt. Simon. The conceptual model guided development of the geocellular model that was constructed using standard geostatistical methods. The resulting geocellular model was statistically evaluated to quantify the change in heterogeneity compared to previous models, which verified an increase in permeability variation and reservoir compartmentalization; however, total pore volume was relatively unchanged. Reservoir simulations indicated that the addition of geological complexity resulted in significant variation in CO₂ saturation and pressure response compared to previous simulations. While the maximum change in pressure remained the same, the response in pressure was distributed over a wider area and extended deeper into the basin. Likewise, CO₂ saturation was more variably distributed laterally and vertically but on a smaller scale. In addition, the increase in model complexity also resulted in reducing the amount of injected CO₂ and a significant increase in the consumption of computer resources, which decreased the overall amount of time simulated. These results highlight the need to take into account geologic variability when estimating GCS potential of a reservoir.

AAPG Datapages/Search and Discovery Article #90350 © 2019 AAPG Annual Convention and Exhibition, San Antonio, Texas, May 19-22, 2019