Giga Cell Compositional Simulation

Simulation models are often compromised (coarse cells, property up-scaling, incomplete physics), due to limitations in simulator technology and access to high computing power. Both computing power and technology have vastly evolved over the past 30 years. Unfortunately, previous choices made in the legacy reservoir simulators have limited their ability to adopt, and hence prevented them from harnessing these advances in an optimal fashion resulting in inefficiencies in parallel runs. We present the results of a next generation highly scalable commercial simulator on a Giga cell multi-component, compositional model of a gigantic field with several hundred wells and several years of production. The previous model was a 5.7 million active cell, multi-component compositional model that did not properly capture the main lateral and vertical heterogeneities. These heterogeneities consist of very thin high permeability streaks that play a major role in the pressure depletion. With the acquisition of a next generation simulator technology, a higher resolution model, with 47 million active cells was built. The performance of our next generation simulator, complemented with in-house developments, was a substantial 4-fold faster in CPU time than the same case using a legacy commercial simulator. However, the average cell size was still in the order of hundreds of meters laterally for this new model. A refinement of the cell size resulted in a billion cell (Giga) model. This model was simulated using our high-performance cluster computer. We also discuss the challenges of the simulation workflow in terms of pre-post Processing and IT environment.