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

Naum I. Gershenzon, Robert W. Ritzi, David F. Dominic, Mohamadreza Soltanian, Edward Mehnert, Roland T. Okwen

Research output: Contribution to journalArticlepeer-review

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.

Original languageEnglish (US)
Pages (from-to)8240-8256
Number of pages17
JournalWater Resources Research
Volume51
Issue number10
DOIs
StatePublished - Oct 2015

Keywords

  • CO2 sequestration
  • capillary trapping
  • heterogeneity
  • scale effects
  • sedimentary architecture

ASJC Scopus subject areas

  • Water Science and Technology

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