Integrated Microbial Trait Based-Reactive Transport Modeling Approach Towards Understanding Microbial Reservoir Souring and Desouring

Microbially mediated sulfate reduction is the major metabolic process that leads to the production of hydrogen sulfide (H2S) in oil reservoirs. Biogenesis of H2S (souring) has detrimental impacts on oil production operations and can cause significant environmental and health problems. Understanding the processes that control the rates and patterns of sulfate reduction is a crucial step in developing a predictive understanding of reservoir souring and associated mitigation processes. In this study, we describe the development of a microbial trait-based model that is coupled to a reactive transport model. The model represents several anaerobic microbial functional guilds with different resource acquisition (e.g., electron donor, sulfate) traits. The integrated model was used to simulate the temporal and spatial evolution of the primary chemical species (e.g. sulfate, sulfide, nitrate, chlorate and perchlorate) and the microbial community dynamics involved in the souring and desouring processes as revealed in a recent laboratory column experiment comparing the effectiveness of nitrate, chlorate and perchlorate treatments as souring control strategies. Simulation of the laboratory experimental results shows that the model captured the spatio-temporal trend of the chemical species and microbial guilds during both souring and desouring. Model parameters derived through modeling of the column data are utilized in subsequent field-scale model simulations across a set of reservoir relevant environmental conditions. This integrated model demonstrates that interactions between SRBs and other heterotrophs can significantly impact the occurrence and extent of H2S production.