Indigenous Microorganisms Map Fluid Distribution in 4500-m-Deep Formations

Summary As global energy systems transition toward sustainability, subsurface technologies such as carbon capture, utilization, and storage (CCUS), geothermal energy, and hydrogen storage are increasingly critical for mitigating carbon emissions. However, a key challenge in these technologies is the effective monitoring and prevention of subsurface fluid or gas leakage. With this study, we present one of the deepest and most extensive microbial distribution maps to date, covering reservoir formations at depths of 3700 m to 4500 m, where temperatures range from 140°C to 160°C. Unlike previous microbial mapping efforts, which are typically limited to shallower depths and lacking integration with logging curves, in this study we construct a microbial distribution map by collecting drilling cuttings and performing high-throughput deoxyribonucleic acid (DNA) sequencing. By correlating microbial community structures with well-logging data, we identified abundant and distinct microbial markers that respond sensitively to fluid presence and environmental changes within the formation. This mapping approach not only reveals the microbial distribution of the deep subsurface but also offers a biologically informed monitoring method for enhancing the safety and performance of deep geological applications.