Comparison of diagenesis and reservoir quality of microporous lime mudstones (Aptian) between anticline crest and flanks: Abu Dhabi, United Arab Emirates

Mohammad Alsuwaidi; Howri Mansurbeg; Ayesha Alsuwaidi; Sadoon Morad; Aala A.I. Mohamed; Abduljamiu O. Amao; Khalid Al-Ramadan

doi:10.1016/j.marpetgeo.2022.105915

Comparison of diagenesis and reservoir quality of microporous lime mudstones (Aptian) between anticline crest and flanks: Abu Dhabi, United Arab Emirates

Mohammad Alsuwaidi, Howri Mansurbeg, Ayesha Alsuwaidi, Sadoon Morad, Aala A.I. Mohamed, Abduljamiu O. Amao, Khalid Al-Ramadan

Earth Science

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14 Scopus citations

Abstract

The impact of in-situ and migrated oil on diagenesis and reservoir quality of microporous (porosity ≤ nil to 26%; permeability ≤ nil to 3 mD) intra-shelf basinal lime mudstones (Aptian) is constrained by comparing samples from anticline crest (i.e. oil zone) versus flanks (i.e. water zone), Abu Dhabi, United Arab Emirates. Higher porosity and permeability and larger pore-throat radii in the crest than in the flank mudstones is attributed to retardation of calcite cementation in the crest due to oil emplacement. Calcite cement has precipitated as syntaxial micro-overgrowths around micrite particles and as equant microspar in moldic pores and small vugs. Deviation of a large number of samples from this crest versus flanks porosity and permeability trend reflects the impact of other parameters, including: (i) subtle grain-size variations (ii) proportion of intact (i.e. with intragranular pores), versus broken coccolith tests, and (ii) degree of calcite cementation. Calcite cement was sourced by stylolitization of the limestones, which is more frequent and extensive in the flanks than in the crest. Similar bulk δ¹⁸O_VPDB values of calcite in the crest (−7.3‰ to −4.6‰) and flanks (−6.9‰ to −5.5‰) is attributed to closed diagenetic system in the microporous mudstones, which masks the role of burial temperature in fractionation of oxygen isotopes during continued cementation of the water-saturated flank mudstones. The presence of miscellaneous saddle dolomite in the crest and flanks is attributed to the field-wide flow of hot basinal fluids along fractures and stylolites. A conceptual model unravelling the diagenetic and related reservoir-quality evolution pathways of mudstones across an oilfield anticline has been developed. This model has important implications for exploration of tight hydrocarbon reservoirs and improves our understanding of oil migration and emplacement in source rocks.

Original language	British English
Article number	105915
Journal	Marine and Petroleum Geology
Volume	145
DOIs	https://doi.org/10.1016/j.marpetgeo.2022.105915
State	Published - Nov 2022

Keywords

Aptian
Coccoliths
Crest
Diagenesis
Flanks
Lime mudstones
Reservoir quality

UN SDGs

This output contributes to the following UN Sustainable Development Goals (SDGs)

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10.1016/j.marpetgeo.2022.105915

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@article{a66b059d4ed1440884d32c73db07fb8c,

title = "Comparison of diagenesis and reservoir quality of microporous lime mudstones (Aptian) between anticline crest and flanks: Abu Dhabi, United Arab Emirates",

abstract = "The impact of in-situ and migrated oil on diagenesis and reservoir quality of microporous (porosity ≤ nil to 26%; permeability ≤ nil to 3 mD) intra-shelf basinal lime mudstones (Aptian) is constrained by comparing samples from anticline crest (i.e. oil zone) versus flanks (i.e. water zone), Abu Dhabi, United Arab Emirates. Higher porosity and permeability and larger pore-throat radii in the crest than in the flank mudstones is attributed to retardation of calcite cementation in the crest due to oil emplacement. Calcite cement has precipitated as syntaxial micro-overgrowths around micrite particles and as equant microspar in moldic pores and small vugs. Deviation of a large number of samples from this crest versus flanks porosity and permeability trend reflects the impact of other parameters, including: (i) subtle grain-size variations (ii) proportion of intact (i.e. with intragranular pores), versus broken coccolith tests, and (ii) degree of calcite cementation. Calcite cement was sourced by stylolitization of the limestones, which is more frequent and extensive in the flanks than in the crest. Similar bulk δ18OVPDB values of calcite in the crest (−7.3‰ to −4.6‰) and flanks (−6.9‰ to −5.5‰) is attributed to closed diagenetic system in the microporous mudstones, which masks the role of burial temperature in fractionation of oxygen isotopes during continued cementation of the water-saturated flank mudstones. The presence of miscellaneous saddle dolomite in the crest and flanks is attributed to the field-wide flow of hot basinal fluids along fractures and stylolites. A conceptual model unravelling the diagenetic and related reservoir-quality evolution pathways of mudstones across an oilfield anticline has been developed. This model has important implications for exploration of tight hydrocarbon reservoirs and improves our understanding of oil migration and emplacement in source rocks.",

keywords = "Aptian, Coccoliths, Crest, Diagenesis, Flanks, Lime mudstones, Reservoir quality",

author = "Mohammad Alsuwaidi and Howri Mansurbeg and Ayesha Alsuwaidi and Sadoon Morad and Mohamed, {Aala A.I.} and Amao, {Abduljamiu O.} and Khalid Al-Ramadan",

note = "Funding Information: This research work was supported by Khalifa University of Science, Technology and Research (Award No. FSU-2018-15 , CIRA 2019-92 and CIRA-2021-013 ). We would like to thank Abu Dhabi National Oil Company (ADNOC) for their permission to publish this paper. We are grateful to Dr. Salvatore Critelli and the journal reviewers for critical reading of the manuscript. Publisher Copyright: {\textcopyright} 2022 Elsevier Ltd",

year = "2022",

month = nov,

doi = "10.1016/j.marpetgeo.2022.105915",

language = "British English",

volume = "145",

journal = "Marine and Petroleum Geology",

issn = "0264-8172",

publisher = "Elsevier B.V.",

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T1 - Comparison of diagenesis and reservoir quality of microporous lime mudstones (Aptian) between anticline crest and flanks

T2 - Abu Dhabi, United Arab Emirates

AU - Alsuwaidi, Mohammad

AU - Mansurbeg, Howri

AU - Alsuwaidi, Ayesha

AU - Morad, Sadoon

AU - Mohamed, Aala A.I.

AU - Amao, Abduljamiu O.

AU - Al-Ramadan, Khalid

N1 - Funding Information: This research work was supported by Khalifa University of Science, Technology and Research (Award No. FSU-2018-15 , CIRA 2019-92 and CIRA-2021-013 ). We would like to thank Abu Dhabi National Oil Company (ADNOC) for their permission to publish this paper. We are grateful to Dr. Salvatore Critelli and the journal reviewers for critical reading of the manuscript. Publisher Copyright: © 2022 Elsevier Ltd

PY - 2022/11

Y1 - 2022/11

N2 - The impact of in-situ and migrated oil on diagenesis and reservoir quality of microporous (porosity ≤ nil to 26%; permeability ≤ nil to 3 mD) intra-shelf basinal lime mudstones (Aptian) is constrained by comparing samples from anticline crest (i.e. oil zone) versus flanks (i.e. water zone), Abu Dhabi, United Arab Emirates. Higher porosity and permeability and larger pore-throat radii in the crest than in the flank mudstones is attributed to retardation of calcite cementation in the crest due to oil emplacement. Calcite cement has precipitated as syntaxial micro-overgrowths around micrite particles and as equant microspar in moldic pores and small vugs. Deviation of a large number of samples from this crest versus flanks porosity and permeability trend reflects the impact of other parameters, including: (i) subtle grain-size variations (ii) proportion of intact (i.e. with intragranular pores), versus broken coccolith tests, and (ii) degree of calcite cementation. Calcite cement was sourced by stylolitization of the limestones, which is more frequent and extensive in the flanks than in the crest. Similar bulk δ18OVPDB values of calcite in the crest (−7.3‰ to −4.6‰) and flanks (−6.9‰ to −5.5‰) is attributed to closed diagenetic system in the microporous mudstones, which masks the role of burial temperature in fractionation of oxygen isotopes during continued cementation of the water-saturated flank mudstones. The presence of miscellaneous saddle dolomite in the crest and flanks is attributed to the field-wide flow of hot basinal fluids along fractures and stylolites. A conceptual model unravelling the diagenetic and related reservoir-quality evolution pathways of mudstones across an oilfield anticline has been developed. This model has important implications for exploration of tight hydrocarbon reservoirs and improves our understanding of oil migration and emplacement in source rocks.

AB - The impact of in-situ and migrated oil on diagenesis and reservoir quality of microporous (porosity ≤ nil to 26%; permeability ≤ nil to 3 mD) intra-shelf basinal lime mudstones (Aptian) is constrained by comparing samples from anticline crest (i.e. oil zone) versus flanks (i.e. water zone), Abu Dhabi, United Arab Emirates. Higher porosity and permeability and larger pore-throat radii in the crest than in the flank mudstones is attributed to retardation of calcite cementation in the crest due to oil emplacement. Calcite cement has precipitated as syntaxial micro-overgrowths around micrite particles and as equant microspar in moldic pores and small vugs. Deviation of a large number of samples from this crest versus flanks porosity and permeability trend reflects the impact of other parameters, including: (i) subtle grain-size variations (ii) proportion of intact (i.e. with intragranular pores), versus broken coccolith tests, and (ii) degree of calcite cementation. Calcite cement was sourced by stylolitization of the limestones, which is more frequent and extensive in the flanks than in the crest. Similar bulk δ18OVPDB values of calcite in the crest (−7.3‰ to −4.6‰) and flanks (−6.9‰ to −5.5‰) is attributed to closed diagenetic system in the microporous mudstones, which masks the role of burial temperature in fractionation of oxygen isotopes during continued cementation of the water-saturated flank mudstones. The presence of miscellaneous saddle dolomite in the crest and flanks is attributed to the field-wide flow of hot basinal fluids along fractures and stylolites. A conceptual model unravelling the diagenetic and related reservoir-quality evolution pathways of mudstones across an oilfield anticline has been developed. This model has important implications for exploration of tight hydrocarbon reservoirs and improves our understanding of oil migration and emplacement in source rocks.

KW - Aptian

KW - Coccoliths

KW - Crest

KW - Diagenesis

KW - Flanks

KW - Lime mudstones

KW - Reservoir quality

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U2 - 10.1016/j.marpetgeo.2022.105915

DO - 10.1016/j.marpetgeo.2022.105915

M3 - Article

AN - SCOPUS:85138098686

SN - 0264-8172

VL - 145

JO - Marine and Petroleum Geology

JF - Marine and Petroleum Geology

M1 - 105915

ER -

Comparison of diagenesis and reservoir quality of microporous lime mudstones (Aptian) between anticline crest and flanks: Abu Dhabi, United Arab Emirates

Abstract

Keywords

UN SDGs

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