Investigation of sub-core scale fluid flow behaviour within heterogeneous sandstones : the role of deformation bands

Student thesis: Doctoral Thesis

Abstract

Small-scale heterogeneities influence fluid flow at sub-core and reservoir scale. However, the influence of deformation bands, commonly found in high porosity sandstones, is poorly understood. Internal structure of small-scale heterogeneities is investigated with X-ray computed tomography (CT). To this aim, high-resolution, artefacts-free CT images are needed. Beam hardening artefact, in cylindrical-shaped samples, increases the X-ray attenuation values with increasing distance from the centre. A new beam hardening correction technique was developed using a post-processing linearization procedure on the beam hardening curve. The technique is implemented in an automated open-source ImageJ plug-in, and successfully applied on X-ray CT images of homogeneous and heterogeneous samples containing deformation bands. Petrophysical and multiphase properties of heterogeneous sandstones were investigated by performing core flooding experiments with positron emission tomography (PET) and/or X-ray CT imaging. Experiments were conducted on a Navajo sandstone core characterized by diagonal deformation bands and fine-grained laminae. PET images were used to derive the single phase hydrodynamic properties of the core.A drainage experiment (CO2/water) was conducted in the water-saturated core and imaged with a medical X-ray CT scanner. Experimental results and numerical simulations indicate that deformation bands form stronger capillary barriers than laminae.A drainage core flooding experiment (N2/water) was performed on a Navajo sandstone core containing conjugate deformation band clusters. Results show a high N2 saturation in the host rock compartments upstream of a thick cluster of deformation bands, identified as an extreme capillary barrier. At the end of the experiment, host rock compartments show variable N2 saturation. Simulation models demonstrate that the capillary end effect and discontinuities in bands impact fluid saturation. Clusters and individual cataclastic bands strongly affect fluid flow, minimizing crossflow between compartments and promoting fluid compartmentalization. Detailed characterization of deformation bands is necessary for accurate reservoir prediction, both for carbon storage and for enhanced oil recovery.
Date of Award24 Jan 2020
Original languageEnglish
Awarding Institution
  • University Of Strathclyde
SponsorsUniversity of Strathclyde
SupervisorRebecca Lunn (Supervisor) & Zoe Shipton (Supervisor)

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