Upscaling of Two-Phase Flow with Capillary Pressure Heterogeneity Effects

Advisor

Louis Durlofsky

Abstract

In this work, we develop a new iterative global upscaling procedure applicable for two-phase flow with significant capillary pressure heterogeneity effects. These effects are important to include in simulations of carbon storage operations as they can have a strong impact on CO2 movement. The upscaling method entails the use of a global fine-scale two-phase flow simulation for computing the coarse-scale mobility functions. Two techniques for upscaling capillary pressure are considered. One approach applies steady-state capillary-limit computations, and the other involves the numerical computation of upscaled capillary pressure along with the upscaled mobilities. For both approaches, iteration at the coarse-scale level leads to an improvement in the accuracy of the upscaled model.

The new upscaling procedures are applied to synthetic two-dimensional reservoir models. Fine-scale capillary pressure is described using the J-function representation. Different gas injection rates and well locations are considered. The coarse-scale models generated using the new iterative global upscaling algorithm provide significantly more accurate results, relative to reference fine-scale simulations, than do those based on simpler upscaling procedures. The robustness of the upscaled models is also assessed, and the models are shown to provide results of reasonable accuracy for cases involving injection rates or large-scale flow configurations that are different from those used in the upscaling calculations. This means that the upscaled functions can be used under a range of flow conditions and are not restricted to only those applied in the upscaling computations.