Microstructural Analysis from X-ray CT Images of the Brae Formation Sandstone, North Sea. / Thomson, Paul-Ross; Ellis, Rory; Chiarella, Domenico; Hier-Majumder, Saswata.

In: Frontiers in Earth Science, 2020.

Research output: Contribution to journalArticle

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Abstract

3D microtomographic images from 8 samples of the Brae Formation sandstone (North Sea) have been analysed in order to characterise the reservoir quality. The Brae Formation is the primary reservoir rock in the Miller Oil Field, located at the western edge of the South Viking Graben. In this study, we focus on core plugs derived from two cored wells (16/7b-20 and 16/7b-23), and located within the depth interval between 4040 m and 4064 m. We use a binary segmentation technique to separate the solid matrix from the macroporosity using a manual thresholding method on the grayscale image stack acquired from the micro CT scans. Once segmented, we isolate the phases of grain and porosity to measure the average grain size, sorting and volume fraction of macro-porosity and micro-porosity. Additionally, we simulate the absolute permeability to assess the influence of grain size characteristics and porosity variation. Our results indicate that the mean grain size in the sandstones vary between 315-524 microns (or 1.78-1.05 phi units), classifying them as predominantly medium-grained sands. The grain sorting analysis show that all samples are moderately well sorted with phi values ranging between 0.51-0.7 phi units. Within most of our samples, below resolution microporosity exists as cement in the pore space. We see that the fraction of effective porosity shows a non-linear reduction with increase in microporous cement volume fraction.
Original languageEnglish
JournalFrontiers in Earth Science
Publication statusSubmitted - 2020

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