Abstract
This paper presents a procedure from which information contained in 3-Dimensional single energy X-ray computed tomography (XR-CT) images of sedimentary rocks is converted into sub-mm scale resolution core scalar and core image logs. This new data provide a quantitative and compact (data volume reduction of ~90%) description of the XR-CT images. Density-related outputs are calibrated through automatic integration with continuous digital visual core description (VCD) and discrete moisture and density (MAD) property index measurements of selected samples. After lithology-based calibration of the X-ray attenuation coefficients into density values, quantitative displays include: 1) histogram of the distribution of density values and its related statistical parameters, 2) radial and angular distributions of core density values, 3) volume, average density and mass contributions of three core fractions defined by density thresholds corresponding to voids or vugs (VV, density ≤ ~1 g•cm−3), and a break in the histogram of distribution of the density values showing the limit between the damaged (DM) and non-damaged (ND) fractions of the core material, and so, 4) providing a sub-mm scale bulk density core log free of any drilling disturbance. The procedure is illustrated on data from the 365 m deep Hole C9001C drilled off-shore Shimokita (northeast coast of Honshu, Japan). Usage of the outputs include: 1) derivation of sub-mm scale porosity core log, 2) correction of volume sensitive measurements in case of poor core quality and partially filled core liner, and 3) seismic modeling and well ties.
Highlights
Computer Tomography (CT) is a nondestructive, radiation recording technique, which maps the numerical values of the linear attenuation coefficient of X- or gamma- ray through a section of the investigated object
This paper presents a procedure from which information contained in 3-Dimensional single energy X-ray computed tomography (XR-CT) images of sedimentary rocks is converted into sub-mm scale resolution core scalar and core image logs
The presented methodological development for automatic data reduction and quantification of single energy XR-CT scanner images of cores allows 1) identification and quantification of voids/vugs (VV), damaged (DM) and non-damaged (ND) core fractions in terms of volume fraction, average density and mass contribution, 2) estimation of core quality based on abundance of VV and damaged core material fraction (DM) fractions, 3) characterization of local variation of core density in terms of radial and angular density distributions, and 4) derivation of a very-high resolution bulk density core log
Summary
Computer Tomography (CT) is a nondestructive, radiation recording technique, which maps the numerical values of the linear attenuation coefficient of X- or gamma- (photon) ray through a section of the investigated object. It requires the acquisition of two-dimensional radiographs for different positions during step-wise rotation around a central axis, whereby either the source and detector or the sample is moved. The quantitative approach in single energy CT scanner is related to the determination of the sediment bulk density. Based on core-to-core calibration, single energy CT has been used with good results to determine both vertical and transverse profiles of the bulk density of marine cores [12] [16]. Results showed excellent correlations between converted topogram values and Hounsfield Unit (HU) values obtained on the tomograms, as well as between relative bulk densities de-
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
