Imaging shallow gas drilling hazards under three Forties oil field platforms using ocean-bottom nodes

Ronen, Shuki; Rokkan, Arne; Bouraly, R.; Valsvik, Geir; Larson, Leif; Ostensvig, Erik; Paillet, J.; Dynia, Anna; Matlosz, Agata; Brown, Simon; Drummie, S.; Holden, Julian; Koster, Klaas; Monk, David J.; Swanson, Mike

doi:10.1190/tle31040465.1

Cited by 30 publications

(4 citation statements)

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“…Gas accumulations beneath permafrost appear to be a common occurrence in Svalbard and they show no preference to stratigraphic age or geological setting. It is important to remember that none of the wells that encountered sub-permafrost gas were actually looking for it, indeed most hydrocarbon exploration wells aim to avoid such shallow gas accumulations (Ronen et al, 2012).In this study, of eighteen hydrocarbon wells in Svalbard, eight show good evidence of permafrost (44%). Four of these permafrost bearing wells show moveable gas accumulations at the base of permafrost (22% of all wells or 50% of permafrost bearing wells), three clearly show no presence of an accumulation while one contains gas shows.…”

Section: Size Frequency and Consequences Of Gas Accumulationsmentioning

confidence: 73%

Review Article: Permafrost Trapped Natural Gas in Svalbard, Norway

Birchall

Jochmann²,

Betlem

et al. 2021

Preprint

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Abstract. Permafrost has become an increasingly important subject in the High Arctic archipelago of Svalbard. However, whilst the uppermost permafrost intervals have been well studied, the processes at its base and the impacts of the underlying geology have been largely overlooked. More than a century of coal, hydrocarbon and scientific drilling through the permafrost interval shows that accumulations of natural gas trapped at the base permafrost is common. They exist throughout Svalbard in several stratigraphic intervals and show both thermogenic and biogenic origins. These accumulations combined with the relatively young permafrost age indicate gas migration, driven by isostatic rebound, is presently ongoing throughout Svalbard. The accumulation sizes are uncertain, but one case demonstrably produced several million cubic metres of gas over eight years. Gas encountered in two boreholes on the island of Hopen appears to be situated in the gas hydrate stability zone and thusly extremely voluminous. While permafrost is demonstrably ice-saturated and acting as seal to gas in lowland areas, in the highlands it appears to be more complex, and often dry and permeable. Svalbard shares a similar geological and glacial history with much of the Circum-Arctic meaning that sub-permafrost gas accumulations are regionally common. With permafrost thawing in arctic regions, there is a risk that the impacts of releasing of sub-permafrost trapped methane is largely overlooked when assessing positive climatic feedback effects.

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Section: Size Frequency and Consequences Of Gas Accumulationsmentioning

confidence: 73%

Review Article: Permafrost Trapped Natural Gas in Svalbard, Norway

Birchall

Jochmann²,

Betlem

et al. 2021

Preprint

View full text Add to dashboard Cite

show abstract

“…While gas accumulations beneath permafrost have been frequently encountered in wellbores, it is important to remember that none of these were actually looking for it, indeed most hydrocarbon exploration wells aim to avoid such shallow gas accumulations (Ronen et al, 2012). In this study, of eighteen hydrocarbon wells in Svalbard, eight show good evidence of permafrost (44%).…”

Section: Size Frequency and Regional Implicationsmentioning

confidence: 76%

Permafrost trapped natural gas in Svalbard, Norway

Birchall,

Jochmann,

Betlem

et al. 2023

Front. Earth Sci.

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Permafrost is widespread in the High Arctic, including the Norwegian archipelago of Svalbard. The uppermost permafrost intervals have been well studied, but the processes at its base and the impacts of the underlying geology have been largely overlooked. More than a century of coal, hydrocarbon, and scientific drilling through the permafrost in Svalbard shows that accumulations of natural gas trapped at the base of permafrost are common. These accumulations exist in several stratigraphic intervals throughout Svalbard and show both thermogenic and biogenic origins. The gas, combined with the relatively young permafrost age, is evidence of ongoing gas migration throughout Svalbard. The accumulation sizes are uncertain, but one case demonstrably produced several million cubic metres of gas over 8 years. Heavier gas encountered in two boreholes on Hopen may be situated in the gas hydrate stability zone. While permafrost is demonstrably ice-saturated and acting as seal to gas in lowland areas, in the highlands permafrost is more complex and often dry and permeable. Svalbard shares a similar geological and glacial history with much of the Circum-Arctic, suggesting that sub-permafrost gas accumulations are regionally common. With permafrost thawing in the Arctic, there is a risk that the impacts of releasing of methane trapped beneath permafrost will lead to positive climatic feedback effects.

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“…As an example, Ronen et al (2012) use mirror migration of OBS data to identify shallow-drilling hazards in the North Sea. Figure 5d shows that the OBS mirror-migration image fills in the blind zone (green dashed box) that is not viewable by conventional migration of primaries.…”

Section: Vsp and Obs Mirror Migrationmentioning

confidence: 99%