Greenland joins arctic exploration fray

PA Resources holds 87.5% interest in the block with Greenland’s national oil company, NunaOil AS, holding the remaining 12.5%.

At the beginning of 2010, TGS Nopec was completing a 2D survey in Baffin Bay using theBergen Surveyor. The company targeted to make available 28,000 km (17,398 mi) of modern 2D data for the West Greenland Baffin Bay licensing round. Nearby, it has also acquired a further 47,000 km (29,204 mi) of aeromagnetic/aerogravity data in the Ungave Labrador Sea area.

Faroe Petroleum and Noreco both pre-qualified as operators for Greenland’s 2010 Baffin Bay licensing round. The area on offer has been divided into 14 blocks, varying in size from 8,000-15,000 sq km (3,089-5,791 sq mi). The deadline for applications was May 1, and only consortia including a pre-qualified operator could apply. According to Noreco, Greenland and northwest Europe appear to share similar geological characteristics.

There is some recent drilling activity in addition to the seismic exploration. The most recent of these is Cairn Energy’s first well offshore Greenland on the Alpha prospect in the Sigguk block, around 175 km (109 mi) offshore Disko Island on the western side of the mainland.

Cairn has permission to drill four wells, and has the fifth-generation semisubmersibleStena Don and the sixth-generation drillship Stena Forth under contract for a multi-well program off Greenland this summer.

Cairn is targeting the Alpha and T8 exploration prospects, both in water depths of between 300 and 500 m (984-1,640 ft). The wells have planned target depths of 4,200 m (13,780 ft) and 3,250 m (10,663 ft), respectively, and should take 55 and 38 days to drill.

“We can now look forward to drilling up to four exploration wells in the undrilled Baffin Bay basin offshore Disko West…,” says Dr. Mike Watts, deputy chief executive of Cairn Energy.

“The acceleration of this exploration activity off the west coast also provides us with flexibility to include the previously unmapped and undrilled basins off the southern coast of Greenland in our planned future drilling programs.”

The big attraction

While there are no drilling successes so far, potential keeps operators interest in the area. The US Geological Survey Circum-Arctic Resource Appraisal looked at the petroleum prospects everywhere north of the Arctic Circle and estimated a total of 90 Bbbl of oil, 1.67 tcf of natural gas, and 44 Bbbl of recoverable gas liquids might be found. Out of this total, 18 Bboe is ascribed to Greenland.

Permitting attention is focused on western Greenland and eastern Canadian waters, but the geological potential does include the East Greenland Rift Basins Province. The USGS estimates the mean undiscovered, conventional petroleum resources in the province to be approximately 31.4 Bbbl of oil equivalent here. This is an area of 500,000 sq km (193,051 sq mi) in waters less than 500 m (1,640 ft) deep.

The West Greenland/East Canada Province of the USGS study includes Baffin Bay, Davis Strait, Lancaster Sound, and Nares Strait. For reporting purposes, the areas were divided into five assessment units (AUs). The five AUs are named the Eurekan Structures AU, Northwest Greenland Rifted Margin AU, Northeast Canada Rifted Margin AU, Baffin Bay Basin AU, and the Greater Ungava Fault Zone AU.

Geological history

The probabilities used in the accompanying table are figured based on the province geology, says the USGS, to keep the figures comparable for each of the five units. The expectation is for refined estimates based on additional exploration and drilling to be made.

Taken on the whole, the tectonic evolution of the area included multiple rifting events, transpressional and transtensional movement, Baffin Bay basin opening, and the sliding of Greenland away from eastern Canada as the Labrador and Norwegian seas opened.

Physical promise of production comes from current and historical oil seeps. For example, a seep offshore from Scott Inlet in northeastern Canadian water is expected to have Upper Cretaceous marine shale as its source. Oil seeps are found in Albian to Paleogene rocks on Nuussuaq Peninsula and Disko Island. Other potential sources are synrift lacustrine and marine petroleum source rocks possibly deposited in Early Cretaceous grabens.

Geologic details

Nunaoil, the national oil company of Greenland, has described prospectivity offshore West Greenland, also, and offers its conclusions regarding the geology and petroleum prospects.

Recent seismic data, combined with that taken earlier in Greenland’s exploration history, show large potential traps. For example, Fylla shows a single closure that covers more than 200 sq km (77 sq mi) with a gross rock volume more than 56 bcm and some of the area outside it.

The Nunaoil study concludes that the basins off West Greenland contain several source intervals, and the two most distinct are Maastrichtian-Lower Paleocene and Upper Cretaceous. The Nuussuaq oil seeps at Marraat cover more than 40 sq km (15 sq mi). A well drilled in the area found oil-prone source rock typical of late Cretaceous or Tertiary deltaic rocks. The consistent composition of the fluids suggests replenishment is taking place, says Nunaoil.

Marine shales are thought to be West Greenland’s most likely oil-prone source rock. Wet gas shows and oily sandstone have been found in Nuussuaq.

Hydrocarbon indicators

Direct hydrocarbon indicators are found in some of the seismic lines. In the Fylla area mentioned above, several flatspots have been observed and AVO tests indicate hydrocarbons in several closures. Bright spots, possible gas chimneys, and oil slicks from possible seepage are other indicators.

The “open door” areas off southwestern Greenland are available for bidding at any time.

As to possible reservoir characteristics, Lower Cretaceous synrift deposits probably are interbedded sands and shales, suggesting deltaic development and associated channel sands. The sand aprons likely were deposited on fault blocks during the rapid half-graben rotation in the Early Cretaceous.

The Lower Cretaceous Bjarni sandstones seem to be the main Labrador Sea reservoirs. Porosities in the Labrador Sea wells for this section have ranged from 17% to 24%. The North Bjarni gas field has reserves of more than 2.2 tcf in Lower Cretaceous sandstones.

Primary target

The primary target in Marraat, southern Nuussuaq, are the Maastrichtian-Lower Paleocene sandstones. The Itilli slope succession contains 500-600 m gross thickness of sandstones including amalgamated, cross-bedded, and coarse-grained sandstones probably from high-density turbidites in low-sinuosity channels, Nunaoil suggests. The channel deposits form excellent potential reservoirs composed of ribbon-shaped coarse-grained sandstone bodies up to2 km (1.25 mi) wide and up to 50 m (164 ft) thick.

Campanian sandstones found by the GANT-1 well on Nuussuaq are approximately 100 m (328 ft) thick with moderate to good porosities (15-20%).

Hanging-wall apron fan sands or basin-floor sands are also reservoir targets. The Snorri J-90 well encountered significant volumes of hydrocarbons in the Paleocene Gudrid sandstone. This reservoir consists of a fine-grained, well sorted, calcareous sandstone over an underlying fault. Average porosity exceeds 20%.

East Greenland carries its own potential

Earlier survey set the example for Circum-Arctic investigation

Northeast Greenland was the prototype for the new US Geological Survey Circum-Arctic Resource Appraisal because the area shares characteristics with many arctic basins. These similarities include little available data, significant potential, geological uncertainty, and technical barriers including the metocean conditions.

This study was done following new information available through collaboration with the Geological Survey of Denmark and Greenland.

As defined for this study, the project covers approximately 500,000 sq km (193,051 sq mi), most under less than 500 m of water offshore east of Greenland between 70º and 82º North.

Assessment Units

For purposes of this study, the East Greenland Rift Basins Province was subdivided into seven distinctive AU, and five of them were assessed. These are North Danmarkshavn Salt basin, South Danmarkshavn basin, Thetis basin, Northeast Greenland Volcanic Province, and Liverpool Land basin. Jameson Land basin and the Jameson Land basin Subvolcanic Extension were defined but not assessed.

Onshore studies suggest at least four stratigraphic intervals may contain good source rocks for liquid petroleum. On the basis of related geological history in western Norway and burial history modeling, Upper Jurassic strata may contain promising source rocks.

Trapping mechanisms probably vary across the province. North Danmarkshavn Salt basin likely has structures formed through salt tectonics. South Danmarkshavn and the Northeast Greenland Volcanic Province probably have extensional structures and stratigraphic traps in submarine fan complexes. Tertiatry inversion structures are found along the western margin of South Danmarkshavn, and the horst block separating Danmarkshavn and Thetis basins, may provide traps in fault blocks, along a major unconformity and in various facies-related permeability barriers.

Possible reservoirs are likely in Middle Jurassic sandstones, Upper Jurassic synrift deposits, Cretaceous sand¬stones in submarine fans, progradational sequences of Paleogene, and in Upper Carboniferous to Lower Permian warm-water carbonate sequences. In most cases, marine shales are expected to be the sealing lithologies.

Resource

Most of the undiscovered oil, gas, and natural gas liquids is likely in the offshore parts of the province. The USGS estimates that the East Greenland Rift Basins Province contains approximately (mean) 31,400 MMboe of oil, natural gas, and natural gas liquids. Of the five AUs, North Danmarkshavn Salt and the South Danmarkshavn are estimated to contain the most resources.