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, Vol. 8, 246, 02.07.2020, p. 1-10.

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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, Vol. 8, 246, 02.07.2020, p. 1-10.

Research output: Contribution to journalArticle

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@article{c64f8565b9c34c40861c9eebc7da818c,
title = "Microstructural Analysis from X-ray CT Images of the Brae Formation Sandstone, North Sea",
abstract = "During deposition and subsequent diagenesis, reservoir rocks develop sediment texture and cement phases are formed during the precipitation of secondary minerals such as microcrystalline quartz, calcite and clay fibrous over-growths that contain secondary porosity. The grain size distribution and presence of secondary microporous material can influence the reservoir porosity and permeability. Using 3D X-ray microtomographic images we analyze the grains and pore space in Brae Formation sandstones from the South Viking Graben in the North Sea. The samplesderived from two cored wells (16/7b-20 and 16/7b-23), and located within the depth interval between 4040 m and 4064 m-display mean grain sizes between 315-524 microns (1.78-1.05 φ units), classifying them as predominantly medium-grained sands, with moderate to well sorting (0.51-0.7 φ units). From our models we calculate the upper and lower bounds of the micropores on the pore connectivity and permeability. Our samples show total porosities between 10 and 18% of which 6 and 13% are effective, leading to a permeability range between 1 and 400 mD through the effective macropore network. We found that the fraction of effective porosity and effective permeability shows a nonlinear reduction with increase in microporous cement volume fraction. Above a threshold cement volume of approximately 5.5% the effective pore network is disconnected and percolation is no longer possible. Based on our observations and modeling results we propose that cement precipitation can be a positive consequence of mineral trapping from sequestered CO2 , which can be important for reducing reservoir quality and ensuring efficient long term storage. ",
keywords = "Digital Rock Physics, 3D Grain Size, Porosity, Brae Formation Sandstone,, Permeability, Petrophysics, Microporosity, Cementation",
author = "Paul-Ross Thomson and Rory Ellis and Domenico Chiarella and Saswata Hier-Majumder",
year = "2020",
month = jul,
day = "2",
doi = "10.3389/feart.2020.00246",
language = "English",
volume = "8",
pages = "1--10",
journal = "Frontiers in Earth Science",

}

RIS

TY - JOUR

T1 - Microstructural Analysis from X-ray CT Images of the Brae Formation Sandstone, North Sea

AU - Thomson, Paul-Ross

AU - Ellis, Rory

AU - Chiarella, Domenico

AU - Hier-Majumder, Saswata

PY - 2020/7/2

Y1 - 2020/7/2

N2 - During deposition and subsequent diagenesis, reservoir rocks develop sediment texture and cement phases are formed during the precipitation of secondary minerals such as microcrystalline quartz, calcite and clay fibrous over-growths that contain secondary porosity. The grain size distribution and presence of secondary microporous material can influence the reservoir porosity and permeability. Using 3D X-ray microtomographic images we analyze the grains and pore space in Brae Formation sandstones from the South Viking Graben in the North Sea. The samplesderived from two cored wells (16/7b-20 and 16/7b-23), and located within the depth interval between 4040 m and 4064 m-display mean grain sizes between 315-524 microns (1.78-1.05 φ units), classifying them as predominantly medium-grained sands, with moderate to well sorting (0.51-0.7 φ units). From our models we calculate the upper and lower bounds of the micropores on the pore connectivity and permeability. Our samples show total porosities between 10 and 18% of which 6 and 13% are effective, leading to a permeability range between 1 and 400 mD through the effective macropore network. We found that the fraction of effective porosity and effective permeability shows a nonlinear reduction with increase in microporous cement volume fraction. Above a threshold cement volume of approximately 5.5% the effective pore network is disconnected and percolation is no longer possible. Based on our observations and modeling results we propose that cement precipitation can be a positive consequence of mineral trapping from sequestered CO2 , which can be important for reducing reservoir quality and ensuring efficient long term storage.

AB - During deposition and subsequent diagenesis, reservoir rocks develop sediment texture and cement phases are formed during the precipitation of secondary minerals such as microcrystalline quartz, calcite and clay fibrous over-growths that contain secondary porosity. The grain size distribution and presence of secondary microporous material can influence the reservoir porosity and permeability. Using 3D X-ray microtomographic images we analyze the grains and pore space in Brae Formation sandstones from the South Viking Graben in the North Sea. The samplesderived from two cored wells (16/7b-20 and 16/7b-23), and located within the depth interval between 4040 m and 4064 m-display mean grain sizes between 315-524 microns (1.78-1.05 φ units), classifying them as predominantly medium-grained sands, with moderate to well sorting (0.51-0.7 φ units). From our models we calculate the upper and lower bounds of the micropores on the pore connectivity and permeability. Our samples show total porosities between 10 and 18% of which 6 and 13% are effective, leading to a permeability range between 1 and 400 mD through the effective macropore network. We found that the fraction of effective porosity and effective permeability shows a nonlinear reduction with increase in microporous cement volume fraction. Above a threshold cement volume of approximately 5.5% the effective pore network is disconnected and percolation is no longer possible. Based on our observations and modeling results we propose that cement precipitation can be a positive consequence of mineral trapping from sequestered CO2 , which can be important for reducing reservoir quality and ensuring efficient long term storage.

KW - Digital Rock Physics

KW - 3D Grain Size

KW - Porosity

KW - Brae Formation Sandstone,

KW - Permeability

KW - Petrophysics

KW - Microporosity

KW - Cementation

U2 - 10.3389/feart.2020.00246

DO - 10.3389/feart.2020.00246

M3 - Article

VL - 8

SP - 1

EP - 10

JO - Frontiers in Earth Science

JF - Frontiers in Earth Science

M1 - 246

ER -