Abstract

We emphasize the importance of microbiology in modern reservoir engineering as well as its interaction with other reservoir components and engineering fundamentals. Underground hydrocarbon and water reservoirs are unique deep-subsurface ecosystems and are characterized by extreme conditions, including high temperatures and pressures, high salinity levels, and an anaerobic gas content with considerable diversity of physiologically distinct microorganisms present in these reservoirs. Clearly, the development of microbial consortia and the activities of these communities have a substantial influence on reservoir environments, consequently exerting a significant impact on reservoir performance studies. The formation of Hydrogen Sulfide (H₂S) in petroleum reservoirs through the activity of anaerobic microorganisms (specifically, Sulfate-Reducing Bacteria, SRB) is known as biogenic souring of reservoirs. Microbial Enhanced Oil Recovery (MEOR) involves the action of microbes by reacting with a substrate to form metabolites to recover a part of the remaining oil in the reservoir after primary and secondary recoveries. Since Geologic Carbon Storage (GCS) is designed for long-term CO₂ sequestration, containment of the storage formation is the most important aspect; therefore, any microbiological impact on the integrity of the overlying formations is of particular interest. Methanogenesis and H2S formation are cited as among the challenges of Underground Hydrogen Storage (UHS). Current technological developments provide excellent opportunities for microbiological monitoring of reservoirs and production facilities, enabling the timely implementation of effective mitigation measures.