Advanced Geomechanical Model to Predict the Impact of CO2-Induced Microstructural Alterations on the Cohesive-Frictional Behavior of Mt. Simon Sandstone

Ange-Therese Akono,Charles Werth,Zhuofan Shi,Theodore Tsotsis,Kristian Jessen

doi:10.3390/min11010038

Ange-Therese Akono, Charles Werth + Show 3 more

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https://doi.org/10.3390/min11010038

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Abstract

We investigated the influence of CO2-induced geochemical reactions on the cohesive-frictional properties of host rock within the context of CO2 storage in a saline aquifer and focused on the Mt. Simon sandstone. The research objective was to model geo-mechanical changes due to host rock exposure to CO2-saturated brine while accounting for heterogeneity, double-scale porosity, and granular structure. We formulated a three-level multi-scale model for host rocks. We conducted scanning electron microscopy analyses to probe the microstructure and grid nanoindentation to measure the mechanical response. We derived new nonlinear strength upscaling solutions to correlate the effective strength characteristics and the macroscopic yield surface to the micro-structure at the nano-, micro-, and meso-scales. Specifically, our theoretical model links CO2-induced microstructural alterations to a reduction in the size of the yield surface, and a drop in the value of the friction coefficient. In turn, regarding the Illinois Basin Decatur Project, the CO2-induced drop in friction coefficient is linked to an increase in the risk of fault slip and a higher probability of induced microseismicity during and after the end of CO2 underground injection operations. The theoretical model presented is essential for the geo-mechanical modeling of CO2 underground injection operations at multiple length-scales.

Highlights

Published: 31 December 2020Geological sequestration of carbon dioxide (CO2 ) into saline aquifers is a broad geophysics application that has fascinated the scientific community for nearly two decades.A specific example is the Illinois Basin Decatur project, which is the first publicly-funded large-scale CO2 underground storage project in the United States with a total budget of$200 M [1]
We explored potential microstructural changes, following incubation in CO2 -saturated brine, using scanning electron microscopy and our theoretical model
Based on our theoretical approach, we carefully examine the case of the US DOEfunded Illinois Basin Decatur Project (IBDP)

Summary

Introduction

Published: 31 December 2020Geological sequestration of carbon dioxide (CO2 ) into saline aquifers is a broad geophysics application that has fascinated the scientific community for nearly two decades.A specific example is the Illinois Basin Decatur project, which is the first publicly-funded large-scale CO2 underground storage project in the United States with a total budget of$200 M [1]. Geological sequestration of carbon dioxide (CO2 ) into saline aquifers is a broad geophysics application that has fascinated the scientific community for nearly two decades. A specific example is the Illinois Basin Decatur project, which is the first publicly-funded large-scale CO2 underground storage project in the United States with a total budget of. A significant number of residual microseismic events was recorded after cessation of CO2 underground injection activities [2]. To explain these observations, the prevailing hypothesis advanced is that CO2 –rock interactions induce a weakening of the mechanical response with the potential of activating faults [3]. For the Illinois Basin Decatur project, this prevailing hypothesis remains unproven, many years later

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