Upscaling: A Tool of the Past?

Edith Lagendijk (1), John Killough (2) and Ulisses T. Mello (3)

(1) Heriot-Watt University
(2) Landmark Graphics
(3) IBM Thomas J. Watson Research Center, Yorktown Heights, NY 10598

Abstract

In the past, reservoir description grids were far too fine to be used as grids in reservoir simulation. Most full-field reservoir simulation models used fewer than 100,000 cells, a factor of 100 down on the geological grid. Upscaling was needed to bridge the gap between these two scales and the industry has put a significant amount of effort into developing single phase and two-phase upscaling algorithms.
This study evaluates several single phase and two-phase upscaling techniques, which are applied to the Eugene Island reservoir model. The results from the upscaled models are compared with the output from the detailed geological model, which are all simulated in a parallelised version of the commercial reservoir simulator VIP. Additionally, several types of grid refinements are discussed and their effects on simulation results analysed.
It is concluded that both single phase and two-phase upscaling can improve the fluid flow performance in the upscaled model of the Eugene Island reservoir. However, small errors in the upscaling procedure can have major implications on simulation results. In addition, the generation and use of pseudo functions can be limited due to time and computation constraints. To prevent errors resulting from upscaling, the fine- scale reservoir description model should be simulated, now made possible by recent advances in parallel computing.