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New filtration parameters from X-ray computed tomography for tight rock images

Krakowska-Madejska Paulina

Geology, Geophysics and Environment

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2022

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Vol. 48, no. 4

381--392

EN

New parameters are proposed to evaluate the filtration properties of rocks obtained on the basis of 3D interpretation of images from X-ray computed tomography. The analyzed parameters are: global average pore connectivity, average blind pore connectivity, blind pore coefficient per object and blind pore coefficient per branch. The 3D pore space from computed X-ray tomography must be subjected to a process of pore space transformation into a skeleton. Then, the presented parameters can be evaluated, taking into consideration the pore channels (branches), pore channel connection points (junctions) and blind pores (pore without connection to the other pore). The calculations were made for low porosity sandstones, mudstones, limestones, and dolomites which differ in terms of age and depth of present deposition. The global average pore connectivity reflects the degree of development of the pore space in which the formation fluid can flow. The higher the global average pore connectivity, the most complex the pore structure can be expected. The higher the parameter of the average blind pore connectivity, the worse are the filtration properties of the rock. The higher the concentration of blind pore coefficient per object or branch, the worse the filtration properties of the rock. Moreover, new parameters were compared with the Euler characteristic and coordination number, revealing a high consistency.

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Detailed parametrization of the pore space in tight clastic rocks from Poland based on laboratory measurement results

Krakowska Paulina

Acta Geophysica

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2019

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Vol. 67, no. 6

1765--1776

EN

Computed X-ray tomography (CT), together with nuclear magnetic resonance spectroscopy, pulse- and pressure-decay permeability methods, is a source of comprehensive information about the geometrical parameters of the pore space. Geological material consists of 31 samples of tight, gas-bearing, clastic rocks from different wells and formations. The purpose was to parametrize in detail the pore structure, revealing the relationships between the various parameters and estimating the equation for assessing the fluid flow ability of analyzed tight rocks. Following parameters were taken into consideration in the pore space characterization: thickness mean, equivalent diameter, anisotropy, elongation, sphericity, Feret diameter, Feret coefficient, Feret shape; shape factors: 2nd circularity coefficient, Malinowska coefficient and Danielsson coefficient; as well as parameters from 3D skeleton analysis: junctions, branches, coordination number. It was captured the dependence of logarithmic T2 mean from NMR on junction count from CT, as well as T2 cutoff from NMR on elongation from CT for the all samples. Logarithm of absolute permeability was estimated based on multiple linear regression analysis using only geometrical parameters from X-ray nanotomography, which is a benefit in the times of coring material decrease.

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Technical note. The concept of a computer system for interpretation of tight rocks using X-ray computed tomography results

Habrat M., Krakowska P., Puskarczyk E., Jędrychowski M., Madejski P.

Studia Geotechnica et Mechanica

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2017

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Vol. 39, nr 1

101--107

EN

The article presents the concept of a computer system for interpreting unconventional oil and gas deposits with the use of X-ray computed tomography results. The functional principles of the solution proposed are presented in the article. The main goal is to design a product which is a complex and useful tool in a form of a specialist computer software for qualitative and quantitative interpretation of images obtained from X-ray computed tomography. It is devoted to the issues of prospecting and identification of unconventional hydrocarbon deposits. The article focuses on the idea of X-ray computed tomography use as a basis for the analysis of tight rocks, considering especially functional principles of the system, which will be developed by the authors. The functional principles include the issues of graphical visualization of rock structure, qualitative and quantitative interpretation of model for visualizing rock samples, interpretation and a description of the parameters within realizing the module of quantitative interpretation.