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Organic geochemical, palynofacies, and petrographic analyses examining the hydrocarbon potential of the Cretaceous (Albian) Kharita Formation in the Matruh Basin, northwestern Egypt

Organic geochemical, palynofacies, and petrographic analyses examining the hydrocarbon potential of the Cretaceous (Albian) Kharita Formation in the Matruh Basin, northwestern Egypt
Organic geochemical, palynofacies, and petrographic analyses examining the hydrocarbon potential of the Cretaceous (Albian) Kharita Formation in the Matruh Basin, northwestern Egypt
A recent study of selected samples from the Cretaceous (Albian) Kharita Formation of Egypt revealed very good to excellent source rock (SR) potential for six intraformational, organic-rich intervals. This work investigates the SR potential of the entire Kharita Formation across the Matruh Basin, using samples from two wells: the Abu Tunis 1X well from the central part of the basin, and the Siqeifa 1X well drilled on the eastern margin of the basin. More strongly reducing conditions were developed in the centre of the basin, and resulted in the deposition of more organic-rich shales by comparison to the less reducing conditions that prevailed on the eastern basin margin, where the shales contain less organic matter. Deltaic intraformational shales and carbonates in the Kharita Formation of Abu Tunis 1X constitute a significant 120 m net of the potential SR. The lower Kharita Formation contains 34 m net shale SR of good to very good/excellent organic richness, yielding values of 1.14–11.59 wt % total organic carbon (TOC). The organic matter has low Hydrogen Index (HI) values (184–389 mg HC/g TOC) and amorphous organic matter (AOM) and relatively high non-opaque phytoclast frequencies indicating mainly gas/oil-prone organofacies (kerogen types II/III). The upper Kharita is more important, containing 86 m net shale/carbonate SR that has fair to good organic richness (0.8–1.8 wt % TOC), and lower HI (126–250 mg HC/g TOC), a dominance of non-opaque phytoclasts, and subordinate AOM frequencies, which together indicate gas/oil-prone organofacies (kerogen Types III/II). In the Siqeifa 1X well, Kharita deltaic intraformational shales and shaley dolostones comprise 80 m net SR, which has mainly fair to good to less very good organic richness (0.8–2.1 wt % TOC), whilst low HI (93–220 mg HC/g TOC), dominance of non-opaque phytoclasts and subordinate AOM indicate gas-prone organofacies (kerogen Type III). A relative upward increase in deposition of lignite and coaly carbonaceous material supports a gas-prone organofacies. Whilst thermal maturity indices only point to immature to early mature (pre- to early oil-window) SRs in both the Abu Tunis 1X and Siqeifa 1X wells, hydrocarbon exploration focussing on this potential source rock may be justified in areas to the southeast of the Matruh Basin, where modelling indicates this unit may have reached the late mature oil- to main gas-generation window.
Palynofacies, Organic petrology; Rock-Eval pyrolysis; Organofacies; Hydrocarbon potential; Kharita Formation; Matruh Basin; Egypt
0264-8172
Deaf, A.S.
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Tahoun, Sameh
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Gentzis, Thomas
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Carvajal-Ortiz, Humberto
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Harding, Ian C.
5d63b829-a9a7-447f-aa3f-62e8d0e715cb
Marshall, John E.A.
cba178e3-91aa-49a2-b2ce-4b8d9d870b06
Ocubalidet, Seare
318faf2e-1142-44f0-baae-b6691b5b2642
Deaf, A.S.
eaaa1c65-6024-4268-8473-ab0fcc118ef9
Tahoun, Sameh
99420dd0-97da-4cf9-a083-11d192393b74
Gentzis, Thomas
c7820c41-0f55-4576-91a1-ae5eccd52a2e
Carvajal-Ortiz, Humberto
409f9447-6391-42e6-9a47-3118bdf19623
Harding, Ian C.
5d63b829-a9a7-447f-aa3f-62e8d0e715cb
Marshall, John E.A.
cba178e3-91aa-49a2-b2ce-4b8d9d870b06
Ocubalidet, Seare
318faf2e-1142-44f0-baae-b6691b5b2642

Deaf, A.S., Tahoun, Sameh, Gentzis, Thomas, Carvajal-Ortiz, Humberto, Harding, Ian C., Marshall, John E.A. and Ocubalidet, Seare (2020) Organic geochemical, palynofacies, and petrographic analyses examining the hydrocarbon potential of the Cretaceous (Albian) Kharita Formation in the Matruh Basin, northwestern Egypt. Marine and Petroleum Geology, 112, [104087]. (doi:10.1016/j.marpetgeo.2019.104087).

Record type: Article

Abstract

A recent study of selected samples from the Cretaceous (Albian) Kharita Formation of Egypt revealed very good to excellent source rock (SR) potential for six intraformational, organic-rich intervals. This work investigates the SR potential of the entire Kharita Formation across the Matruh Basin, using samples from two wells: the Abu Tunis 1X well from the central part of the basin, and the Siqeifa 1X well drilled on the eastern margin of the basin. More strongly reducing conditions were developed in the centre of the basin, and resulted in the deposition of more organic-rich shales by comparison to the less reducing conditions that prevailed on the eastern basin margin, where the shales contain less organic matter. Deltaic intraformational shales and carbonates in the Kharita Formation of Abu Tunis 1X constitute a significant 120 m net of the potential SR. The lower Kharita Formation contains 34 m net shale SR of good to very good/excellent organic richness, yielding values of 1.14–11.59 wt % total organic carbon (TOC). The organic matter has low Hydrogen Index (HI) values (184–389 mg HC/g TOC) and amorphous organic matter (AOM) and relatively high non-opaque phytoclast frequencies indicating mainly gas/oil-prone organofacies (kerogen types II/III). The upper Kharita is more important, containing 86 m net shale/carbonate SR that has fair to good organic richness (0.8–1.8 wt % TOC), and lower HI (126–250 mg HC/g TOC), a dominance of non-opaque phytoclasts, and subordinate AOM frequencies, which together indicate gas/oil-prone organofacies (kerogen Types III/II). In the Siqeifa 1X well, Kharita deltaic intraformational shales and shaley dolostones comprise 80 m net SR, which has mainly fair to good to less very good organic richness (0.8–2.1 wt % TOC), whilst low HI (93–220 mg HC/g TOC), dominance of non-opaque phytoclasts and subordinate AOM indicate gas-prone organofacies (kerogen Type III). A relative upward increase in deposition of lignite and coaly carbonaceous material supports a gas-prone organofacies. Whilst thermal maturity indices only point to immature to early mature (pre- to early oil-window) SRs in both the Abu Tunis 1X and Siqeifa 1X wells, hydrocarbon exploration focussing on this potential source rock may be justified in areas to the southeast of the Matruh Basin, where modelling indicates this unit may have reached the late mature oil- to main gas-generation window.

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Deaf et al 2019-MPG-accepted - Accepted Manuscript
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Accepted/In Press date: 10 October 2019
e-pub ahead of print date: 15 October 2019
Published date: February 2020
Keywords: Palynofacies, Organic petrology; Rock-Eval pyrolysis; Organofacies; Hydrocarbon potential; Kharita Formation; Matruh Basin; Egypt

Identifiers

Local EPrints ID: 435237
URI: http://eprints.soton.ac.uk/id/eprint/435237
ISSN: 0264-8172
PURE UUID: 6b019229-5e8f-45cb-a241-e29b70cf1517
ORCID for Ian C. Harding: ORCID iD orcid.org/0000-0003-4281-0581
ORCID for John E.A. Marshall: ORCID iD orcid.org/0000-0002-9242-3646

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Date deposited: 28 Oct 2019 17:30
Last modified: 15 Oct 2020 04:01

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Contributors

Author: A.S. Deaf
Author: Sameh Tahoun
Author: Thomas Gentzis
Author: Humberto Carvajal-Ortiz
Author: Ian C. Harding ORCID iD
Author: Seare Ocubalidet

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