Abstract
This paper describes a simulation study of 103D El-Giza, an unusual multi-layered bottom water-drive carbonate reservoir in Libya that features a unique pre-mature water-out, caused not by aquifer invasion but by a massive casing leak of injection water from an underlying reservoir. The circumstances surrounding the reservoir’s water-out and subsequent revival to normal production when injection was halted, sheds the light on the existence and extent of a unique 4.5-darcy high permeability vuggy layer in the middle of the formation. The location and confirmation of this dominating high permeability layer led to the identification of a significant attic oil accumulation.
The objectives of the study were to quantify the strength of the aquifer, identify trapped and bypassed oil, and investigate a strategy to optimize their recovery. These were accomplished after solving the puzzle of the early water-leakage, including its location, volume, and profile, and sorting out its impact on the natural water-drive system.