438549 Numerical Experiments of Density Driven CO2 Saturated Brine Migration in Heterogeneous Geologic Fabric Materials

Sunday, November 8, 2015
Exhibit Hall 1 (Salt Palace Convention Center)
Akand Islam, Department of Petroleum & Geosystems Engineering, The University of Texas at Austin, Austin, TX

CO2 geological sequestration has been recognized as one of the potential solutions for reducing anthropogenic emissions. To better estimate the storage efficiency (capacity) and to understand the plume migration mechanism through porous geologic formations this study performs numerical experiments of density driven CO2 saturated brine flow in meter-scale, highly resolved heterogeneous 2D fabrics.  Two aspects of heterogeneity are examined. The first relates to the correlation length of the sedimentary structures, or depositional fabric, of the material. The second aspect of heterogeneity evaluated is based on correlation length. 27 clastic facies of three different fabrics that are representative of a variety of typical geologic materials were selected for our experiments. These materials have horizontal correlation lengths that vary over 3 orders of magnitude and range from extremely well sorted upper-coarse sand to very poorly sorted upper-coarse silt. We have considered density difference as the main driving force of plume migration due to natural convection through the facies. Migration behavior from both saturated perturbed side and top boundaries are tested. The analysis is done using mass and momentum conservations, and the Darcy law. Our primary results show that convective migration is possible only in a limited range of facies, extremely well and well sorted coarse sands whose global permeability and porosity meet the critical Rayleigh number (≈4π2). Results indicate that convective and dissolution processes are influenced by both the range in grain size (permeability) and the correlation length of the sedimentary fabric, and that these behaviors are not expected in a surprisingly large number of typical geologic materials.

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