Modeling and simulating biogenically-controlled permeability in gas reservoirs

This study investigates the impact of biogenically influenced permeability and burrow connectivity on gas production, particularly in sedimentary strata with Thalassinoides burrow networks. Using multipoint statistics models, the study examines two distinct Thalassinoides configurations: as connected networks and as isolated volumes. The study assesses various permeability levels across millidarcy, microdarcy, and nanodarcy scales in both Thalassinoides cells and the host rock matrix cells in a 1-m cube model. A series of 12 fluid flow simulation cases, spanning these configurations and permeability scales, are analyzed to explore the interplay between permeability contrasts and burrow connectivity, and their collective impact on gas production. The results reveal that both the level of permeability and the contrast in permeability between the burrow fillings and the host rock matrix, along with the pattern of burrow connectivity, significantly influences gas flow dynamics. In scenarios with high permeability contrast (of three orders of magnitude), a connected burrow network can have divergent effects on gas production, either enhancing or inhibiting it. Conversely, in systems with low permeability contrast, the impact of burrow connectivity on gas flow is minimal. In these cases, the permeability of the host rock matrix emerges as the predominant factor influencing gas production efficiency, thus overshadowing the role of burrow connectivity. This research advances our understanding of the complex interplay between burrow structures and gas reservoir dynamics and has significant implications for optimizing extraction strategies and reservoir management in gas production from sedimentary strata.