Simulation of Hydrogen Sulfide Generation in Oil and Gas Geological Formations

Abstract

Hydrogen sulphide generation in subsurface formation–of ten dubbed as souring--is a phenomenon that happens as a result of in-situ biodegradation reactions during and after the water-flooded reservoir. This phenomenon is caused by sulfate-reducing microorganisms, which a group composed of sulfate-reducing bacteria and sulfate-reducing archaea. Sulfate-reducing bacteria, by oxidizing a carbon source, sulfate ions can be turned into hydrogen Sulfide. Furthermore, Water cut, temperature, pressure, and fluid chemistry can affect the concentration observed. This paper introduced a simulation model that describes We simulated H2 S generation (souring) at subsurface formation utilizing a 2D model. The conditions that are favorable for souring are met in the constructed model. We chose STARS- CMG--an advanced Process Thermal Compositional Simulator –to simulate the aftermath of geochemical and chemical reactions. The bacterial-induced souring. The results suggest that bacterial activity has consumed the sulfate in the aqueous phase. Such consumption was seen as the SO4 concentration dropped from 1.8e-05-6.0e-06mo1/L. The consumed SO4 was converted into H2 S or caused water souring. The souring occurrence was inferred by the sharp increase in H2 S concentration that reached a maximum of $\sim$0.0006mo1/L. The introduced simulation approach could serve as a way of predicting the aftermath of biodegradation reactions that causes H2 S generation in the subsurface.