Abstract
The Thamama B reservoirs in Abu Dhabi onshore fields represent over 50% of the total reserves of the country. Therefore, the optimization of production and the maximization of recovery are of paramount importance. While reserves are distributed uniformly in the reservoir, the permeability distribution is heterogeneous, with top layers being more permeable (100 mD to 1D than lower ones (1 to 10 mD). This has a strong impact on water flooding performance and requires a thorough understanding of the reservoir fluid flow physics and behaviour, focusing on the detailed analysis of the water hold-up and slumping mechanisms, including the origin and shape of the existing water cones in the lower zones and the bypassed oil zones.
Study results showed that the management of Thamama B reservoirs needs to be achieved through the combination of high quality field surveillance programmes, associated with detailed reservoir studies developed specifically for the modelling of the water advance in the reservoir.
A mechanistic model of a Thamama B reservoir in an Abu Dhabi onshore field was created to determine which parameters, and respective uncertainty ranges, have the greatest impact on fluid dynamics. These were identified to be: rock wettability, (and the associated capillary pressure and relative permeability curves), and the presence of high permeability and dense intervals within the reservoir, both in the upper and lower zones. Once the parameters are identified, it is then vital to reduce the associated uncertainty, by fine tuning the models and undertaking representative forecasts.
The hereby proposed way forward concentrates on monitoring the reservoir performance and build refined reservoir models that can be easily used to understand the reservoir mechanisms and to characterize and accurately predict the water movement in the Thamama B reservoirs, in order to be able to establish the most adequate field development methodologies leading to the optimization of production and to the maximization of ultimate recovery.
