Multiscale Mixed-Finite-Element Modeling of Coupled Wellbore/Near-Well Flow

Abstract

Summary An accurate well-modeling capability is important for both production- and reservoir-engineering calculations. Ideally, the models used for these two applications should be related in a logical manner. Multiscale methods allow varying degrees of resolution and can, therefore, provide a natural link between production and reservoir models. In this paper, we present a coupled wellbore-/reservoir-flow model that is based on a multi-scale mixed-finite-element formulation for reservoir flow linked to a drift/flux wellbore-flow representation. The model is able to capture efficiently the effects of near-well heterogeneity in the reservoir and phase holdup and pressure variation in the well-bore. The formulation presented here is for oil/water systems. The basic reservoir/wellbore linkage is described and validated through comparison to results from an existing simulator. The multiscale method is then applied to a heterogeneous-reservoir model. Both vertical and deviated wells are considered. Comparisons of the multiscale solution to the fully resolved (fine-scale) solution demonstrate the efficiency and high degree of accuracy of the method for both reservoir and wellbore quantities.