Geological Characterization and Modelling of Gas Transport in Midra Shale

Abstract

CO2 capture and sequestration are increasingly becoming more essential for a sustainable energy market. Fossil fuel industry requires CO2 sequestration, and it has the necessary means as well. Essential mechanisms such as mineral trapping and residual trapping of CO2 can be implemented in Qatari reservoirs due to the presence of Calcite and other unique clay minerals such as Palygorskite. Qatari Midra Shale dominantly consists of Palygorskite which is utilized as an adsorbent in the industry. Its unique fibrous lath like structure provides a higher specific surface area for more adsorption relative to the calcite found in Alveolina limestone and Rus formation in general. Additionally, the pore widths are determined to have relative larger size in comparison to shale reservoirs from USA and Mexico. Additionally, the study done in this thesis includes a gas transport model that can relate to the characterization of Midra shale, and a simple gas production model was developed. Furthermore, geo-chemical reactions between Palygorskite and CO2 (with water) were also studied. Initially, the study deals with the comprehensive characterization of Midra shale and how it is accomplished. Additionally, pore characterization is done in order to report the higher pore volume and pore widths of Palygorskite. Furthermore, the sorptive analyses of the Midra shale were correlated with findings from the prior characterization based on mineralogy, organic content and pore characteristics. To further develop on the hypothesis, investigation and proposal of a representative gas transport model for Midra shale, and an example study of gas production from a hypothetical Midra shale reservoir containing Methane was done. Finally, the process of mineral trapping in Palygorskite was studied by replicating a simple reactive transport model. The model provided an overview of the evolution of the porosity due to any mineral alteration or dissolution. It provides additional credibility towards the complete study done on whether Midra Shale can be a potential “Sink” or a “Source”.