Simulation of Bacterial Souring Control in an Albertan Heavy Oil Reservoir

This paper presents the development of a simulation model describing the bacterial-induced souring of an Albertan heavy oil-producing field and its remediation by injection of nitrate. An area of the field with extensive bacterial activity was selected for the simulation study. The primary production and waterflood injection phases were history matched with basic reservoir maps and injection/production operating conditions, adjusted by an automatic history match algorithm. Extensive chemical and microbiological compositional data for injected and produced waters were collected and analyzed at the University of Calgary and a mathematical model of the souring process and its remediation treatment was developed, based on the information collected. Simulation indicated the volumetric distribution of the hydrogen sulfide over time and how the injected nitrate was distributed and acted to achieve souring control. Predicted individual production well responses were shown to be consistent with field observations, and issues regarding improved monitoring and design of laboratory experiments for future field operations are highlighted. Hence, simulation can be a useful tool in understanding and designing remedial treatments to bacterial souring in the Western Canada Sedimentary Basin.