Original scientific paper

https://doi.org/10.4154/gc.2021.17

Evaluation Of 3D small-scale lithological heterogeneities and pore distribution of the Boda Claystone Formation using X-Ray Computed Tomography images (CT)

Saja Mohammad Abutaha orcid.org/0000-0001-8439-5895 ; University of Szeged, Department of Geology and Paleontology; 6722, Szeged, Egyetem utca 2-6, Hungary
Janos Geiger orcid.org/0000-0001-9359-5266 ; University of Szeged, Department of Geology and Paleontology; 6722, Szeged, Egyetem utca 2-6, Hungary
Sándor Gulyás orcid.org/0000-0002-3384-2381 ; University of Szeged, Department of Geology and Paleontology; 6722, Szeged, Egyetem utca 2-6, Hungary
Ferenc Fedor orcid.org/0000-0002-1938-9496 ; GEOCHEM Ltd, 55/1 Viola str., Kozármisleny, H-7761, Hungary

Abstract

This study was undertaken to quantify and evaluate the density and porosity characteristics of a Boda Claystone Formation (BCF) core sample using medical CT. Each voxel of the 3D CT volume was described with three variables: dry CT number, saturated CT number, and effective porosity. Disparity pore voxels were revealed using the genetic groups’ algorithm of data-mining techniques. The K-fold cross-validation algorithm has been applied to determine the number of the most stable cluster. The 3D spatial distributions of voxel-porosity by rock constituents, as well as the 3D distribution of porosity clusters by rock components, were found by  Boolean function implementation.The terrigenous detrital fragments had the lowest porosity mean (0.16%) and highest coefficient variation value (1039.39%). While the Fine siltstone component had the highest porosity mean (3.39%) and lower coefficient of variation (134.99%). The difference in the variation of coefficient proportions is related to the outlier ratios in each rock component.Independently of both the rock types and the sedimentary structures, two clusters could be defined: one for the micro-porosity and one for the macro-porosity regimes. The former showed a continuous 3D spatial appearance, while the latter appeared in patches. These patches may also be connected, at least partly, to some local smectite aggregates. These clay minerals could lose their structured water content during vacuuming and swell when adsorbing water during sample saturation. In each rock type, the micro-porosity regime could be related to low-density rock fragments. The mean effective porosity of the micro-pore regime was about 0.02, which corresponds to the petrophysical core measurements. For the macro regimes, the average was 0.1.

Keywords

Boda Claystone Formation; CT; data mining; Boolean function; authigenic mineral

Hrčak ID:

265330

URI

https://hrcak.srce.hr/265330

Publication date:

27.10.2021.

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