Influence of small‐scale fluvial architecture on CO₂ trapping processes in deep brine reservoirs

Abstract

A number of important candidate CO2 reservoirs exhibit sedimentary architecture reflecting fluvial deposition. Recent studies have led to new conceptual and quantitative models for sedimentary architecture in fluvial deposits over a range of scales that are relevant to CO2 injection and storage. We used a geocellular modeling approach to represent this multiscaled and hierarchical sedimentary architecture. With this model, we investigated the dynamics of CO2 plumes, during and after injection, in such reservoirs. The physical mechanism of CO2 trapping by capillary trapping incorporates a number of related processes, i.e., residual trapping, trapping due to hysteresis of the relative permeability, and trapping due to hysteresis of the capillary pressure. Additionally, CO2 may be trapped due to differences in capillary entry pressure for different textural sedimentary facies (e.g., coarser‐grained versus finer‐grained cross sets). The amount of CO2 trapped by these processes depends upon a complex system of nonlinear and hysteretic characteristic relationships including how relative permeability and capillary pressure vary with brine and CO2 saturation. The results strongly suggest that representing small‐scale features (decimeter to meter), including their organization within a hierarchy of larger‐scale features, and representing their differences in characteristic relationships can all be critical to understanding trapping processes in some important candidate CO2 reservoirs.

Critical Dynamics of Gravito-Convective Mixing in Geological Carbon Sequestration

“…The main processes controlling the trapping of CO 2 during geological sequestration are storage of supercritical CO 2 in a gas cap, CO 2 dissolution in brine, known as solubility trapping78, residual trapping due to hysteresis910, and mineral trapping by CO 2 precipitation as secondary carbonates11. In this work, we focus on solubility trapping, which can be enhanced when gravitational instabilities (fingering) are triggered by a local increase in brine density as CO 2 dissolves into brine in the top of an aquifer.…”

“…Facies distributions therefore affect species transport through a formation9. Architectures of sedimentary facies can exhibit sharp discontinuities across boundaries between depositional features, for instance across the sandstone-shale contacts that are common in fluvial deposits.…”

“…Architectures of sedimentary facies can exhibit sharp discontinuities across boundaries between depositional features, for instance across the sandstone-shale contacts that are common in fluvial deposits. The complex patterns in such fluvial architectures30 exist in many candidate aquifers for CO 2 sequestration93132 and result in variable connectivity and tortuous flow pathways33. Representing such discontinuous, correlated heterogeneity in reservoir simulations is non-trivial34, and its influence on the characteristics of density-driven flow has not been studied in detail.…”

Influence of CO2‐wettability on CO2 migration and trapping capacity in deep saline aquifers

“…26 One factor, which has received little attention, is the CO 2 -wettability of the rock. One of the key parameters, which has received little attention, is CO 2 -wettability.…”

Gaussian process modelling for uncertainty quantification in convectively-enhanced dissolution processes in porous media

“…To the best of our knowledge, there are only a limited number of publications in the literature (e.g., [24]) dealing with multi-phase flow and reactive transport models of CO 2 sequestration and the associated trapping process, taking into account the impact of heterogeneity on front spreading and mass transfer between high and low permeability zones of the heterogeneous medium, together with the impact of physical and chemical heterogeneity on the chemical reactions. Most of the literature on enhanced dissolution in CO 2 sequestration is concerned with the time evolution of the process and not with the analysis of the non-uniqueness of solutions, the corresponding bifurcation map and the stability of solutions.…”