In this work, high-resolution (pressure decay profile permeametry, PDPK and image analysis porosimetry) techniques supported by more conventional core analysis measurements and integrated with macroproperty measurements have been used in the detailed fault seal analysis of deformation bands from two different geological settings. The Hopeman Sandstone, (Inner Moray Firth Basin) is host to cataclastic deformation bands and the sandstone samples from the U.K. sector of southern North Sea host clay-rich bands. With the exception of cemented deformation bands, their formation is shown to be highly dependent upon the composition of the host rock. Detailed PDPK permeability and image analysis porosity maps document microscale changes in permeability and porosity across deformation bands which have experienced varying levels of cataclasis, clay mixing and cementation processes. The greater difference in permeabilities and porosities of deformation bands relative to host rock using these techniques compared to conventional nitrogen permeametry and helium, mercury and Nuclear Magnetic Resonance (NMR) porosimetry is the outcome of their higher spatial resolution resulting in measurements of much smaller volumes or rock. Together with pore-size distribution, capillary pressure, (Scanning electron microscopy, SEM and mercury) grain size and macroproperty characterisation, these results show much reduced deformation band storage capacities relative to the host rock and illustrates their influence as baffles to flow. This effect has been observed directly using positron emission tomography (PET) scanning of deformation bands. Cemented deformation bands (observed using cathodoluminescence, CL) locally tighten the Hopeman Sandstone but are discontinuous and unlikely to have a large impact on fluid flow throughout the fault damage zone.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:593237 |
| Date | January 2000 |
| Creators | Ogilvie, S. |
| Publisher | University of Aberdeen |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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