HR: 16:45h
AN: OS34A-03    [Abstracts]
TI: Automatic Quantification of X-ray Computed Tomography Images of Cores: Method and Application to Shimokita Cores (Northeast Coast of Honshu, Japan)
AU: * Gaillot, P
EM: gaillotp@jamstec.go.jp
AF: IFREE - CDEX / JAMSTEC, Yokohama Institute for Earth Sciences 3173-25 Showa-machi, Kanazawa-ku, Yokohama, 236-0001, Japan
AB: X-ray computed tomography (CT) of rock core provides nondestructive cross-sectional or three-dimensional core representations from the attenuation of electromagnetic radiation. Attenuation depends on the density and the atomic constituents of the rock material that is scanned. Since it has the potential to non-invasively measure phase distribution and species concentration, X-ray CT offers significant advantages to characterize both heterogeneous and apparently homogeneous lithologies. In particular, once empirically calibrated into 3D density images, this scanning technique is useful in the observation of density variation. In this paper, I present a procedure from which information contained in the 3D images can be quantitatively extracted and turned into very-high resolution core logs and core image logs including (1) the radial and angular distributions of density values, (2) the histogram of distribution of the density and its related statistical parameters (average, 10- 25- 50, 75 and 90 percentiles, and width at half maximum), and (3) the volume, the average density and the mass contribution of three core fractions defined by two user-defined density thresholds (voids and vugs < 1.01 g/cc <e; damaged core material < 1.25 g/cc < non-damaged core material). In turn, these quantitative outputs (1) allow the recognition of bedding and sedimentary features, as well as natural and coring-induced fractures, (2) provide a high-resolution bulk density core log, and (3) provide quantitative estimates of core voids and core damaged zones that can further be used to characterize core quality and core disturbance, and apply, where appropriate, volume correction on core physical properties (gamma-ray attenuation density, magnetic susceptibility, natural gamma radiation, non-contact electrical resistivity, P-wave velocity) acquired via Multi- Sensors Core loggers (MSCL). The procedure is illustrated on core data (XR-CT images, continuous MSCL physical properties and discrete Moisture and Density measurements) from the Hole C9001C drilled off-shore Shimokita (northeast coast of Honshu, Japan) during the shake-down cruise (08-11/2006) of the scientific drilling vessel, Chikyu.
UR: http://pgaillot.ifrance.com/CTscan/indexctscan.html
DE: 0520 Data analysis: algorithms and implementation
DE: 0540 Image processing
DE: 5194 Instruments and techniques
SC: Ocean Sciences [OS]
MN: 2007 Fall Meeting