Experimental Characterization of Shale Microstructure, Adsorption, and Wettability in the Presence of CO2

Abstract

This thesis presents a comprehensive investigation into the CO2 adsorption characteristics of shale samples, with a specific focus on understanding how shale microstructure and wettability influence CO2 sequestration potential. Given the increasing interest in carbon capture and storage as a strategy to mitigate atmospheric CO2 levels, shale formations have been identified as potential candidates for CO2 storage due to their abundant availability and unique geological features. The aim of this study lies in the experimental investigation of the relationships between the microstructural properties of shale, including porosity, mineralogy, and organic content, its wettability characteristics, and the consequent effects on CO2 adsorption capacity.

A series of experimental analyses were conducted on a range of shale samples, which were characterized by varying mineralogical compositions, porosity, total organic content, and wettability profiles. The mineralogy of the samples was determined using X-ray diffraction, while their average porosity was obtained through scanning electron microscopy. Adsorption was measured through volumteric adsorption measurement setup at varying pressures and temperature while contact angle dataset of shale/CO2/brine systems was assessed for wettability chracterization, providing insights into the affinity of shale surfaces for CO2.

The results revealed a significant correlation between the microstructural properties of shale and its CO2 adsorption capacity. Samples with higher TOC levels demonstrated enhanced CO2 adsorption, attributed to increased available surface area and the presence of organic matter that may act as preferential adsorption sites. The results suggest that high TOC shales, at high pressure, and relatively lower temperatures depict the greatest CO2 storage potential in shale via adsorption trapping. Furthermore, the study identified a link between shale wettability and CO2 adsorption, with more CO2-wettable surfaces showing higher adsorption capacities, suggesting that wettability modification could be a potential strategy to optimize shale formations for CO2 storage.

This research contributes to the growing body of knowledge on CCS technologies and provides valuable insights into the selection and preparation of shale formations for efficient CO2 sequestration. The findings highlight the importance of detailed characterization of shale microstructure and wettability in predicting and enhancing its CO2 adsorption performance, potentially contributing to the development of CO2 geo-storage technologies and the general understanding of unconventional reservoirs.

Date of Award	7 May 2024
Original language	American English
Supervisor	Muhammad Arif (Supervisor)