Diagenetic fluid transport in fractured shale using laboratory rock/fluid interactions data to analyze sealing potential

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Conference Proceeding

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Subsurface fluids that are super-saturated can influence the extent to which defective natural caprocks are sealed. The convective transport of such fluids are of interest in other to provide effective containment for sequestered CO in targeted repositories. Fracture geometry largely govern fluid flow characteristics in deep micro-fractured formations, it has been postulated that the effect of mineralization can lead to flow impedance in the presence of favorable geochemical and thermodynamic conditions. Simulation results suggested that influx-induced mineral dissolution/precipitation reactions within clay-based sedimentary rocks can continuously close micro-fracture networks, though injection pressure and effective-stress transformation first rapidly expand the fractures. This experimental modelling research investigated the impact of in-situ geochemical precipitation on conductivity of fractures under carbon sequestration conditions. Geochemical analysis were performed on four samples of natural shale rocks, effluent fluids and recovered precipitates both before and after CO -brine flooding at temperature and pressure conditions similar to that of the subsurface. Bulk rock geomechanical hardness was determined using Vickers' micro-indentation. Differential pressure drop data across fractured composite core were also measured with respect to time over a five day period. This was used in estimating the conductivity of the artificially fractured cores. The estimates of 1st order pressure derivative and dimensionless fracture conductivity indicated that reactive transport of dissolved minerals in aqueous fluids can occlude microfracture flow paths in naturally fractured shale rocks. 2 2

Publication Source (Journal or Book title)

51st US Rock Mechanics / Geomechanics Symposium 2017

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