Petroleum Geology of the Dreki area on the Jan …IEC-2008 1 Petroleum Geology of the Dreki area on...

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Petroleum Geology of the Dreki area on the Jan Mayen

Ridge

Þórarinn Sveinn ArnarsonHydrocarbon Licensing Manager

National Energy Authority, Energy Resources

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Acknowledgements• Steinar Þór Guðlaugsson and Bjarni Richter

– Formerly at Iceland Geosurvey (ÍSOR), now at GeysirGreen Energy

• Anett Blischke at Iceland Geosurvey• Many previous contributors

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Outline

• Introduction to the Icelandic continental shelf• Overview of geological research of the area• Geology of the Jan Mayen Ridge• Hydrocarbon resource potential of the Jan

Mayen Ridge

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Outline

• Introduction to the Icelandic continental shelf

• Overview of geological research of the area• Geology of the Jan Mayen Ridge• Hydrocarbon resource potential of the Jan

Mayen Ridge

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Icelandic Continental Shelf

• Solid lines: EEZ boundaries

• Dashed lines: continental shelf claims by Iceland

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Northern Dreki licensing round

Three areas on the Icelandic continental shelf with potential for commercial accumulations of oil and gas

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Oil shows

Oil and gas fields

Jan Mayen Ridge

NorthernDreki area

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The northern Dreki area in relation to hydrocarbon basins in East Greenland, the North Sea and offshore western

Norway and Shetland

• Jan Mayen Ridge geologically similar to neighbouring hydrocarbon basins

• Next door neighbours prior to the opening of the northeast Atlantic ocean basin

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JM Agreement Area

Northern Dreki Area

Jan Mayen

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Bathymetric map and limits of the northern

Dreki Area

• Water depths in the northern Dreki Area mostly range from 800 to 2000 m

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NorthernDrekiArea

Jan MayenAgreementArea

Jan Mayen

IcelandIceland GeoSurvey2008

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Outline

• Introduction to the Icelandic continental shelf• Overview of geological research of the

area• Geology of the Jan Mayen Ridge• Hydrocarbon resource potential of Jan

Mayen Ridge

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Academic interest in the geology of the Jan Mayen Ridge

• The Jan Mayen Ridge is magnetically quiet

• It is a microcontinent – a piece of continental crust stranded in the middle of the northeast Atlantic

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Academic research of the Jan Mayen Ridge –multi channel seismic

• French survey in 1975 (Cepan 1) by CNEXO

• German survey by Bundesanstalt für Geowissenschaften und Rohstoffe in 1975 and 1976

• British cruise by the University of Durham in 1977

• University of Bergen survey in 1978, mostly on the northern part of the ridge

• US cruise by Lamont-Doherty Geological Observatory in 1979

• University of Oslo survey in 1986Iceland GeoSurvey 2008

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• NPD-survey in 1979• NPD-NEA survey in 1985• NPD-NEA survey in 1988

• Total: 5500 km of 2D-seismic lines

Icelandic and Norwegian seismic surveys

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• Non-exlusive, prospecting survey in 2001• 2800 km of 2D-

seismic data• Additional 850 km infill

survey in 2008(approximate locations)

Seismic surveys by Wavefield-Inseis

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Seismic refraction data

• Sonobuoy locations (red dots) from NPD-NEA surveys in 1985 and 1988

• Expanding Spread Profiles (blue lines and dots) by Institut Francais du Petrole in 1987 and L-DGEO in 1979

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Deep Sea Drilling Project boreholes

• Five shallow boreholes drilled in the area during DSDP Leg 38 in 1974• Water depths ranged

between 700 and 1800 m• Penetration depths

ranged between 180 and 550 m

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Outline

• Introduction to the Icelandic continental shelf• Overview of geological research of the area• Geology of the Jan Mayen Ridge• Hydrocarbon resource potential of the Jan

Mayen Ridge

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Bott 1985

The Jan Mayen Ridge (light brown) was separated from the continental shelfs of Greenland and Norway

by plate tectonic movements

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Bott 1985

Subsequently new ocean floor (blue) was gradually created around active oceanic ridges

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Bott 1985

Kolbeinsey Ridge initially most active in the south, Aegir Ridge becomes extinct

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Bott 1985

Jan Mayen Ridge continues to move away from Greenland as a result of sea-floor spreading

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Oceanic crust in the Norway Basin

Wedge-shaped piles of lava flows formed at the beginning of seafloor-spreading in the Norway basin when the ridge was separated from the Norwegian continental shelf: -Younger pile

-Older pile

Continental crust with sediments and a layer of lava flows:-Relatively undisturbed

-Extended and extensively faulted during separation from Greenland

Composite sheet of flatlying intrusives covering subsided continental crust just before oceanic crust started to form on the Iceland Plateau

Oceanic crust on the Iceland Plateau

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B

Gunnarsson, Sand & Gudlaugsson, 1989

Simplified geological map of the Jan Mayen Ridge: based on the 1985 survey

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Gunnarsson, Sand & Gudlaugsson, 1989

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Gunnarsson, Sand & Gudlaugsson, 1989

Igneous features at the eastern margin of the Jan Mayen Ridge and their stratigraphic relationship to sedimentary layers

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57 mya (anomaly 24R) Gunnarsson, Sand & Gudlaugsson, 1989

Initial breakup of the continent and eruption of lavas

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50 mya (anomaly 21) Gunnarsson, Sand & Gudlaugsson, 1989

Sediment accumulation on the East Greenland margin

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30 mya (anomaly 10) Gunnarsson, Sand & Gudlaugsson, 1989

Rifting within the East Greenland margin – erosion of the top of the ridge, submarine fans

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21 mya (anomaly 6A) Gunnarsson, Sand & Gudlaugsson, 1989

Breakup to the west of the ridge and emplacement of submarine lavas or sills

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PresentGunnarsson, Sand & Gudlaugsson, 1989

Subsidence due to cooling and thermal contraction. Sedimentation mostly pelagic, some gravity flows

down steep ridge slopes

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Outline

• Introduction to the Icelandic continental shelf• Overview of geological research of the area• Geology of the Jan Mayen Ridge• Hydrocarbon resource potential of the

Jan Mayen Ridge

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Potential surface seeps• Unconfirmed report of gasses in shallow cores within

the northern Dreki area by Soviet scientists on the Akademic Kurchatov in 1973• Interpreted as indications of deep hydrocarbon

sources• Could also have a shallow source from low-

temperature chemical or biochemical processes

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Results from DSDP boreholes• Shallow penetration – only to

Late Eocene age (~40 m.y.)• Sediments with fairly low total

organic content• Oil genesis of organic matter

at a very early stage

• Boreholes did not reach deep enough!

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Potential source rocks

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Potential source rocks• Tertiary post-rift source rocks

• Time of restricted water exchange early in the rifting phase may have resulted in accumulation of organic matter in sediments

• Pre-rift source rocks• Possible analogies with continental margins on

either side of the ocean• The Jan Mayen Ridge was separated earlier from

the Norwegian side than from Greenland• Not known which parts of the Mezosoic or

Paleozoic sequence is present

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Preliminary hydrocarbon maturation modelling

• Two heat flow cases• Moderate heat flow• High heat flow

• Caveats• Uncertainty in subsidence history• Sills may increase maturation locally• Level of maturation strongly influenced by highest

temperature experienced – heat pulses may have large impact

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Preliminary hydrocarbon maturation modelling

Gunnarsson, Sand & Gudlaugsson, 1989

High heat flow: Early Eocene source-rocks have reached oil window

Tertiary source rocks: Immature

Mesozoic source rocks: In gas window ( high)In oil window (moderate)

Tertiary source rocks: At most very early oil-matureMesozoic source rocks: Overcooked (high)In late oil or gas window

(moderate)

Tertiary source rocks:

Early Eocene early oil-mature (moderate)

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Sheet of basalt intrusives

Wedge of lava flows

Listric fault complex

Transverse structural/volcanic high

Sills above lavas

Normal fault

Reverse fault

Areas with potentialhydrocarbon traps

From Åkermoen 1989 & Sagex 2006

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From Sagex 2006 and Åkermoen 1989

Areas with potential hydrocarbontraps, from Sagex (2006)

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Surface pockmarks in the northern Dreki area

• Surface pockmarks were discovered in June 2008 during a multibeam-study of the Dreki area led by Gudrún Helgadóttir of the Marine Research Institute

• Pockmarks had been found on the Norwegian side during the 1985 survey

• Pockmarks have been found at the bottom of the North sea, and sometimes cluster around major hydrocarbon fields

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Origin of pockmarks• There are several potential explanations for the

formation of pockmarks at the sea floor• They can be a result of eruptions of gashydrates

that have become unstable and get “gassed out”• They can be formed by seepage of gas through

the sea-bottom• This gas could be methane formed in situ at

shallow depth• A deep hydrocarbon source for the gas is also

possible• Analysis of surface sediment cores from pockmarks

and/or fault lines with modern equipment has not been done yet to determine if there is a surface seepage of hydrocarbons in the area

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Satellite hydrocarbon seep study

• The National Energy Authority is funding a preliminary study of satellite radar-images to search for natural oil seepage in the Dreki Area• The leader of the project is Ingibjörg Jónsdóttir,

Associate Professor at the University of Iceland• A report on the investigation is due to be released

in December 2008

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Hydrocarbon Potential in the Dreki Area

• Sedimentary rocks of sufficient thickness and age

• Indications of pre-opening sedimentary strata

• Potental source rocks similar to East Greenland

• Potential reservoir rocks, including submarine fans

• Potential traps present, both structural and stratigraphic

• Seismic anomalies indicate that hydrocarbons may be present