Influence of post-Danian sea-level changes and variations in sedimentation rate on overpressure build up in the clay-rich overburden in the Danish sector of the North Sea Central Graben

Research output: Contribution to journalJournal articleResearchpeer-review

Standard

Influence of post-Danian sea-level changes and variations in sedimentation rate on overpressure build up in the clay-rich overburden in the Danish sector of the North Sea Central Graben. / Orozova-Bekkevold, Ivanka; Rasmussen, Erik Skovbjerg; Schovsbo, Niels Hemmingsen.

In: Journal of Petroleum Geology, Vol. 46, No. 2, 07.04.2023, p. 191-217.

Research output: Contribution to journalJournal articleResearchpeer-review

Harvard

Orozova-Bekkevold, I, Rasmussen, ES & Schovsbo, NH 2023, 'Influence of post-Danian sea-level changes and variations in sedimentation rate on overpressure build up in the clay-rich overburden in the Danish sector of the North Sea Central Graben', Journal of Petroleum Geology, vol. 46, no. 2, pp. 191-217. https://doi.org/10.1111/jpg.12835

APA

Orozova-Bekkevold, I., Rasmussen, E. S., & Schovsbo, N. H. (2023). Influence of post-Danian sea-level changes and variations in sedimentation rate on overpressure build up in the clay-rich overburden in the Danish sector of the North Sea Central Graben. Journal of Petroleum Geology, 46(2), 191-217. https://doi.org/10.1111/jpg.12835

Vancouver

Orozova-Bekkevold I, Rasmussen ES, Schovsbo NH. Influence of post-Danian sea-level changes and variations in sedimentation rate on overpressure build up in the clay-rich overburden in the Danish sector of the North Sea Central Graben. Journal of Petroleum Geology. 2023 Apr 7;46(2):191-217. https://doi.org/10.1111/jpg.12835

Author

Orozova-Bekkevold, Ivanka ; Rasmussen, Erik Skovbjerg ; Schovsbo, Niels Hemmingsen. / Influence of post-Danian sea-level changes and variations in sedimentation rate on overpressure build up in the clay-rich overburden in the Danish sector of the North Sea Central Graben. In: Journal of Petroleum Geology. 2023 ; Vol. 46, No. 2. pp. 191-217.

Bibtex

@article{f2b3e7e3c89d4d499c8b3ddafc65e262,
title = "Influence of post-Danian sea-level changes and variations in sedimentation rate on overpressure build up in the clay-rich overburden in the Danish sector of the North Sea Central Graben",
abstract = "Overpressure build up in the clay-rich succession between sea floor and the top of the Chalk Group in the area around wells North Jens-1 and Fasan-1 in the Danish sector of the Central Graben, North Sea was examined by forward modelling. {"}Overpressure{"}, i.e. fluid pressure higher than hydrostatic pressure, is expressed here in terms of both the difference between pore pressure and hydrostatic pressure at a given depth and the ratio between these pressures. Pore pressure changes over time were estimated by numerical simulation of post-Danian depositional processes, incorporating sea level changes and variations in sedimentation rate. Results show that the deposition of the post-Danian ({"}overburden{"}) succession led to overpressure build up both in the overburden itself and in the underlying sediments (the so-called {"}underburden{"}). The largest estimated present-day overpressures (4.9-5.6 MPa, 23-26% above hydrostatic) occur at the base of the overburden, while an overpressure of up to 5.5 MPa was calculated to occur in the underburden. Variations in sedimentation rate appeared to have influenced the build-up of overpressure in the overburden, although no significant effect was found in the underburden.The results indicate that more than 50% of the present-day overpressure in the overburden was generated in the last 5.3 million years, i.e. during the Pliocene and the Quaternary. When variations in sedimentation rate during the Miocene were included in the modelling calculation, this proportion increased to nearly 70%. A decrease in sedimentation rate in the mid-Miocene (Serravallian, 15-11.2 Ma) and the late Miocene (Messinian, 7.5-5.3 Ma) resulted in the dissipation of overpressures generated previously when the sedimentation rate was higher. About 60% of the overpressure generated in the Miocene developed during the Tortonian but only 14% during the Messinian.Water depth appears to influence the overpressure magnitude. Sea level changes played a minor and short-lived role in overpressure build up. The influence of water depth was most pronounced when it was significantly greater than the thickness of the deposited sediments.The method of overpressure estimation used in this paper may be a valuable alternative to methods based on porosity trend analysis which are widely used in the oil and gas industry. Both the methods used here and the results may be useful in subsurface evaluations related to carbon storage in the Danish Central Graben (e.g. project Green Sand).",
keywords = "Overpressure, Danish Central Graben, North Sea, Cenozoic, depositional process, overburden, mechanical compaction, basin modelling, numerical forward model, finite elements approach, MIOCENE SUCCESSION, MARINE SHALE, BASIN, EVOLUTION, COMPACTION, VELOCITY, STRATIGRAPHY, OLIGOCENE, PALEOGENE, PERMEABILITY",
author = "Ivanka Orozova-Bekkevold and Rasmussen, {Erik Skovbjerg} and Schovsbo, {Niels Hemmingsen}",
year = "2023",
month = apr,
day = "7",
doi = "10.1111/jpg.12835",
language = "English",
volume = "46",
pages = "191--217",
journal = "Journal of Petroleum Geology",
issn = "0141-6421",
publisher = "Wiley-Blackwell",
number = "2",

}

RIS

TY - JOUR

T1 - Influence of post-Danian sea-level changes and variations in sedimentation rate on overpressure build up in the clay-rich overburden in the Danish sector of the North Sea Central Graben

AU - Orozova-Bekkevold, Ivanka

AU - Rasmussen, Erik Skovbjerg

AU - Schovsbo, Niels Hemmingsen

PY - 2023/4/7

Y1 - 2023/4/7

N2 - Overpressure build up in the clay-rich succession between sea floor and the top of the Chalk Group in the area around wells North Jens-1 and Fasan-1 in the Danish sector of the Central Graben, North Sea was examined by forward modelling. "Overpressure", i.e. fluid pressure higher than hydrostatic pressure, is expressed here in terms of both the difference between pore pressure and hydrostatic pressure at a given depth and the ratio between these pressures. Pore pressure changes over time were estimated by numerical simulation of post-Danian depositional processes, incorporating sea level changes and variations in sedimentation rate. Results show that the deposition of the post-Danian ("overburden") succession led to overpressure build up both in the overburden itself and in the underlying sediments (the so-called "underburden"). The largest estimated present-day overpressures (4.9-5.6 MPa, 23-26% above hydrostatic) occur at the base of the overburden, while an overpressure of up to 5.5 MPa was calculated to occur in the underburden. Variations in sedimentation rate appeared to have influenced the build-up of overpressure in the overburden, although no significant effect was found in the underburden.The results indicate that more than 50% of the present-day overpressure in the overburden was generated in the last 5.3 million years, i.e. during the Pliocene and the Quaternary. When variations in sedimentation rate during the Miocene were included in the modelling calculation, this proportion increased to nearly 70%. A decrease in sedimentation rate in the mid-Miocene (Serravallian, 15-11.2 Ma) and the late Miocene (Messinian, 7.5-5.3 Ma) resulted in the dissipation of overpressures generated previously when the sedimentation rate was higher. About 60% of the overpressure generated in the Miocene developed during the Tortonian but only 14% during the Messinian.Water depth appears to influence the overpressure magnitude. Sea level changes played a minor and short-lived role in overpressure build up. The influence of water depth was most pronounced when it was significantly greater than the thickness of the deposited sediments.The method of overpressure estimation used in this paper may be a valuable alternative to methods based on porosity trend analysis which are widely used in the oil and gas industry. Both the methods used here and the results may be useful in subsurface evaluations related to carbon storage in the Danish Central Graben (e.g. project Green Sand).

AB - Overpressure build up in the clay-rich succession between sea floor and the top of the Chalk Group in the area around wells North Jens-1 and Fasan-1 in the Danish sector of the Central Graben, North Sea was examined by forward modelling. "Overpressure", i.e. fluid pressure higher than hydrostatic pressure, is expressed here in terms of both the difference between pore pressure and hydrostatic pressure at a given depth and the ratio between these pressures. Pore pressure changes over time were estimated by numerical simulation of post-Danian depositional processes, incorporating sea level changes and variations in sedimentation rate. Results show that the deposition of the post-Danian ("overburden") succession led to overpressure build up both in the overburden itself and in the underlying sediments (the so-called "underburden"). The largest estimated present-day overpressures (4.9-5.6 MPa, 23-26% above hydrostatic) occur at the base of the overburden, while an overpressure of up to 5.5 MPa was calculated to occur in the underburden. Variations in sedimentation rate appeared to have influenced the build-up of overpressure in the overburden, although no significant effect was found in the underburden.The results indicate that more than 50% of the present-day overpressure in the overburden was generated in the last 5.3 million years, i.e. during the Pliocene and the Quaternary. When variations in sedimentation rate during the Miocene were included in the modelling calculation, this proportion increased to nearly 70%. A decrease in sedimentation rate in the mid-Miocene (Serravallian, 15-11.2 Ma) and the late Miocene (Messinian, 7.5-5.3 Ma) resulted in the dissipation of overpressures generated previously when the sedimentation rate was higher. About 60% of the overpressure generated in the Miocene developed during the Tortonian but only 14% during the Messinian.Water depth appears to influence the overpressure magnitude. Sea level changes played a minor and short-lived role in overpressure build up. The influence of water depth was most pronounced when it was significantly greater than the thickness of the deposited sediments.The method of overpressure estimation used in this paper may be a valuable alternative to methods based on porosity trend analysis which are widely used in the oil and gas industry. Both the methods used here and the results may be useful in subsurface evaluations related to carbon storage in the Danish Central Graben (e.g. project Green Sand).

KW - Overpressure

KW - Danish Central Graben

KW - North Sea

KW - Cenozoic

KW - depositional process

KW - overburden

KW - mechanical compaction

KW - basin modelling

KW - numerical forward model

KW - finite elements approach

KW - MIOCENE SUCCESSION

KW - MARINE SHALE

KW - BASIN

KW - EVOLUTION

KW - COMPACTION

KW - VELOCITY

KW - STRATIGRAPHY

KW - OLIGOCENE

KW - PALEOGENE

KW - PERMEABILITY

U2 - 10.1111/jpg.12835

DO - 10.1111/jpg.12835

M3 - Journal article

VL - 46

SP - 191

EP - 217

JO - Journal of Petroleum Geology

JF - Journal of Petroleum Geology

SN - 0141-6421

IS - 2

ER -

ID: 344902086