| Abstrakt: |
The main objective of this study is to calculate the representative elementary volume (REV) according to voxels’ porosity. Physical properties of rock-forming components of a 5 m-long core sample of the Boda Claystone Formation (BCF) were acquired using 3D X-ray computed tomography images. The REV calculation was established using the Autoregressive Integrated Moving Average, Statistical Process Control (ARIMA SPC) technique. This method (ARIMA SPC) was five times iterated by varying positions of starting voxel volume in the core sample: upper left, upper right, lower left, lower right, and middle. The general average range of REV values was from 16.56 cm3 to 46.26 cm3. Monte Carlo simulation with 1,000 runs was used to simulate the long-run properties of REV and the normalized REV of voxel-porosity. The simulated REV values were 64.80 cm3 in the upper left position, 61.44 cm3 for the upper right, 55.59 cm3 for the lower right, 53.77 cm3 for the lower left, and 42.23 cm3 for the middle. According to the simulation of the normalised REVs, their volume percentages were as follows: 40 % for the upper left, 41.34 % in the lower right, 23.86 % for the lower left. Lastly, the upper right and the central (middle) positions had almost the same percentage volumes around 15.5 %. As the initial volume started from any core sample’s corners, the REV porosity range would be between 2.47 % and 2.58 %, which is close to the average voxel porosity of BCF (2.55%). However, a deviant (higher) REV porosity value was attained from the centre initiated volume (~ 2.8 %). Therefore, the middle part of the studied core sample might not be adequate to be considered as an initial voxel volume of the REV calculation. [ABSTRACT FROM AUTHOR] |
