Abstract
Geological sequestration of CO2 in deep saline formations is a promising means of reducing atmospheric CO2 emissions. Once injected, CO2 dissolves into formation brine, lowering pH and creating conditions favorable for mineral dissolution. Cations released from dissolving minerals may create conditions favorable for secondary mineral precipitation, which can result in the long-term mineralogical trapping of injected CO2. These reactions may alter the natural rock mechanical properties, which can affect the safety and efficiency of geological sequestration. This work aims to investigate the impact of mineral composition and distribution on the mechanical properties of porous media. In this study, the mineralogy, mineral distribution, and mechanical properties of samples from Escambia County, AL, are evaluated. The mechanical properties of the rock samples are evaluated using the unconfined compression and indirect tensile tests in the combination with digital image correlation. The mineral composition and distribution are determined through the analysis of scanning electron microscopy backscattered electron and energy dispersive X-ray spectroscopy images of thin sections. These analyses showed that the mechanical properties vary with composition, which may have significant practical consequences for geological sequestration of CO2.
Highlights
Rapid industrialization and human activities, such as excessive use of automobiles and burning of coal, gases, and oils, have caused an unprecedented increase in the emission of greenhouse gases, especially carbon dioxide (CO2), to the atmosphere causing significant challenges such as climate change and global warming
scanning electron microscopy (SEM) backscattered electron (BSE) and energy dispersive Xray spectroscopy (EDS) images and the final processed images are shown for samples from the two formations Figures 1-3
The main aim of this research was to study the effect of mineral composition, microstructure, and porosity on the rock mechanical properties
Summary
Rapid industrialization and human activities, such as excessive use of automobiles and burning of coal, gases, and oils, have caused an unprecedented increase in the emission of greenhouse gases, especially carbon dioxide (CO2), to the atmosphere causing significant challenges such as climate change and global warming. In spite of its excellent environmental benefits, CO2 capture and storage in underground geological formations implementation is limited This is in part due to a lack of understanding of fundamental water-rock-CO2 interactions, including, for example, the effect of clay mineralogy on the coupled hydro-mechanical phenomena [3,4,5]. Injection of CO2 in saline aquifers results in the formation of carbonic acid and subsequent dissolution of primary minerals and alterations of the natural rock mechanical properties. These processes may affect the safety and efficiency of the geological sequestration process
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