Hydrogen Generation and Fracture Development in Organic-Rich Shale via Thermal Treatment

Abstract

The quest for clean and sustainable energy sources has positioned hydrogen, recognized as the cleanest energy carrier, as a key player in the global energy transition and reduction of carbon emissions. Consequently, global demand for hydrogen is anticipated to grow significantly in both the near and long term, necessitating the development of hydrogen production methods. This study investigates the potential of hydrogen-rich gas generation and fracture development in immature, organic-rich shales through thermal treatment, aiming to enhance the yield of clean hydrogen gas. High-resolution micro-CT imaging was used to examine core samples subjected to varying temperatures (up to 750 °C) to analyze deformation behaviors and fracturing associated with heating and gas generation. Gas Chromatography (GC) was used to analyze the gases generated at various heating temperatures. The results indicate that hydrogen gas production increases significantly with temperature, with hydrogen yields of 0.31% at 100 °C, 1.19% at 200 °C, 9.92% at 300 °C, 30.13% at 400 °C, and 36.02% at 450 °C. Fractures formed predominantly parallel to the bedding planes, which significantly enhanced the permeability of these low-permeability shales, facilitating hydrogen extraction, with optimal hydrogen yields observed at the temperature ranges where fractures begin to initiate. The thermal decomposition of organic matter, in conjunction with fracture development, increased shale permeability, providing a viable strategy for enhanced hydrogen-rich gas generation and extraction. These findings demonstrate that controlled in situ thermal treatment of shale could play a significant role in advancing more efficient and environmentally sustainable hydrogen-rich gas production from organic-rich shale formations, offering a novel approach to maximizing the hydrogen yield and production efficiency.