Przestrzenne badanie systemu porowego skał węglanowych na podstawie cyfrowej analizy obrazów mikrotomograficznych z wykorzystaniem języka "Python"

Adam Fheed, Piotr Hadro


Spatial analysis of carbonate pore system based on digital image analysis of X-ray microtomography data using Python language.
A b s t r a c t. The main aim of this contribution is to combine a Python-supported analysis of X-ray microtomography (µCT) images and the transmitted-light microscopy to resolve the factors controlling the variability of petrophysical parameters in carbonate rocks. A self-developed Python script for the evaluation of pore connectivity and the computation of pore sizes based on µCT data was prepared. The script was launched on a carbonate sample withdrawn from a drill core representing the Late Permian Zechstein Limestone (Ca1) formation from the Wolsztyn Ridge area in West Poland. The sample was taken from the upper part of the isolated Kokorzyn Reef, corresponding to a brachiopod and bivalve-rich zone. The plug had a cylindrical shape, the diameter of 2.54 cm and the height of approximately 4.6 cm. The entire volume of the plug was scanned using a GE Nanotom S device. The 3D-reconstructed dataset obtained with spatial resolution of 0.02 mm underwent cropping, contrast adjustment, noise reduction and porosity extraction using open-source Fiji software. The binarized porosity image was loaded into the Python script. Python scripting was found efficient in carbonate pore system examination. The code first extracted the connected pore system of the largest volume and computed the smallest distances between porosity voxels and corresponding pore walls. The obtained results were confronted with the spatially-adjusted microphotographs taken in plane-polarized transmitted light. The results have shown that narrow and isolated pores occurred within the spines of brachiopods. The largest voids were found inside the brachiopod shells. Moreover, many pores were associated with partially dissolved fragments of bivalves. Porosity reduction was most outlined in the zones showing the scarcity of fossils.

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