Mineral Precipitation in Fractures and Nanopores within Shale Imaged Using Time-Lapse X-ray Tomography

Barite precipitation in fractures and nanopores within a shale sample is analysed in situ, in 3D, and over time. Diffusion of barium and sulphate from opposite sides of the sample creates a supersaturated zone where barium sulphate crystals precipitate. Time-lapse synchrotron-based computed tomograp...

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Bibliographic Details
Published in:Minerals (Basel) 2019-08, Vol.9 (8), p.480
Main Authors: Godinho, Jose R. A., Ma, Lin, Chai, Yuan, Storm, Malte, Burnett, Timothy L.
Format: Article
Language:English
Subjects:
3D imaging
Barite
Barium
Calcite
Chemical precipitation
Computational fluid dynamics
Computed tomography
Crystal growth
Crystal structure
Crystallization
Crystals
Earth sciences
Experiments
Fluid flow
Fluids
formation damage
fracking
Fracture surfaces
Hydraulic fracturing
Ion transport
Microscopy
mineral precipitation
Minerals
Morphology
Permeability
Porosity
porous media
Precipitation
scale
Sedimentary rocks
Shale
Shales
Sulfates
time-lapse imaging
Tomography
X ray imagery
X rays
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Summary:Barite precipitation in fractures and nanopores within a shale sample is analysed in situ, in 3D, and over time. Diffusion of barium and sulphate from opposite sides of the sample creates a supersaturated zone where barium sulphate crystals precipitate. Time-lapse synchrotron-based computed tomography was used to track the growth of precipitates over time, even within the shale’s matrix where the nanopores are much smaller than the resolution of the technique. We observed that the kinetics of precipitation is limited by the type and size of the confinement where crystals are growing, i.e., nanopores and fractures. This has a major impact on the ion transport at the growth front, which determines the extent of precipitation within wider fractures (fast and localised precipitation), thinner fractures (non-localised and slowing precipitation) and nanopores (precipitation spread as a front moving at an approximately constant velocity of 10 ± 3 µm/h). A general sequence of events during precipitation in rocks containing pores and fractures of different sizes is proposed and its possible implications to earth sciences and subsurface engineering, e.g., fracking and mineral sequestration, are discussed.
ISSN:2075-163X
2075-163X
DOI:10.3390/min9080480