Characterization of rock matrix block size distribution, dispersivity, and mass transfer coefficients in fractured porous media
Date
2013-10-02
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Abstract
Fractured porous media are important structures in petroleum engineering and geohydrology. The accelerating global demand for energy has turned the focus to fractured formations. The fractured porous media are also found in conventional naturally fractured reservoirs and the water supply from karst (carbonate) aquifers. Studying mass transfer processes allows us to explore the complexities and uncertainties encountered with fractured rocks. This dissertation is developing an analytical methodology for the study of mass transfer in fractured reservoirs.
The dissertation begins with two cases that demonstrate the importance of the rock matrix block size distribution and dispersivity through a transient mass exchange mechanism between rock matrix blocks and fractures. The first case assumes a medium with no surface adsorption, and the second case includes the surface adsorption variable.
One of the main focuses of this work is the characterization of the rock matrix block size distribution in fractured porous media. Seismic surveying, well test analysis, well logging, and geomechanical tools are currently used to characterize this property, based on measurements of different variables. This study explores an innovative method of using solute transport to determine the fracture intensity. This methodology is applied to slab-shaped rock matrix blocks and can easily be extended to other geometries.
Another focus of this dissertation is the characterization of dispersivity in field scale studies. Improving our knowledge of dispersivity will enable more accurate mass transfer predictions and advance the study of transport processes. Field tracer tests demonstrated that dispersivity is scale-dependent. Proposed functions for the increasing trend of dispersivity include linear and asymptotic scale-dependence. This study investigated the linear dispersivity trend around the injection wellbore. An analysis of the tracer concentration in a monitoring well was used to characterize the slope of the linear function for different rock geometries.
The final part of the study is the development of a lumped mass transfer coefficient between fractures and rock matrix blocks with different geometries. The obtained lumped mass transfer coefficient confirms that the scale of study, dispersivity, and the rate of injection of the fluid into the wellbore are important variables in solute transport in fractured rocks.
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Hydrology, Petroleum
Citation
Sharifi Haddad, A. (2013). Characterization of rock matrix block size distribution, dispersivity, and mass transfer coefficients in fractured porous media (Doctoral thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca. doi:10.11575/PRISM/25288