Modeling Geological CO2 Sequestration: Translations Across Spatial Scales and Advancements in Nonlinear Newton Solver

Advisors

Sally M. Benson, primary advisor
Hamdi Tchelepi, primary advisor
Peter K. Kitanidis, advisor

Abstract

Characterization of formation heterogeneity is the first step for constructing geological models that are used in simulating subsurface flow migration, such as CO₂ geological storage and oil/gas recovery. Technologies such as seismic survey, well logging, and core analysis reveal the formation heterogeneity at different scales. Due to the computational limitations on model construction and flow simulation, the gridblock size of a geological model is usually much larger than a core. The common industry practice is to assign core-scale properties directly to a geological model gridblock. The sub-grid- and sub-core-scale heterogeneities are neglected. The objective of this work is two-fold. First, we demonstrate that these small-scale heterogeneities can influence large-scale CO₂ migration during geological storage. Significant modeling error may occur if these heterogeneities are not accounted for properly. Second, we improve the nonlinear convergence performance of numerical simulation, which is a crucial tool for translating small-scale physics in large-scale modeling and for uncertainty quantifications during the scale-up. A new Newton solver is developed, which converges quickly by avoiding the oscillations and overshoots that are often encountered in traditional solvers.