Abstract
Tar mats are extra-heavy bitumen that occur between aquifers and overlaying oil columns. They seal either partially or completely an oil reservoir from its aquifer and reduces aquifer support. Tar characterization includes evaluation of the tar distribution and its sealing degree. It is an important prerequisite to optimize the water injection well's requirement and placement to maximize sweep and recovery.
This paper discusses a case study and demonstrates an integrated methodology by using static and dynamic data to determine the tar distribution and its sealing degree. The study includes both early life data before the subject field was put in production, as put on production, and post-production data to refine the characterization. Additionally, the use of formation pressure while drilling and Pyrolytic Oil-Productivity Index (POPI) analysis to optimize the injector's placement will also be highlighted. Moreover, saturation and production logging tool analysis were incorporated to determine if there is aquifer influx across the tar mat. The degree of the aquifer influx is also evaluated using material balance and reservoir simulation.
