GREENLAND TO GATHER MORE EXPLORATION DATA

Danish authorities are taking steps to make more exploration data available on Greenland in advance of a possible West Greenland shelf licensing round in 1993.

Seismic data acquisition and other studies continue toward more fully evaluating Greenland's oil and gas potential.

Geological Survey of Greenland (GGU), Copenhagen, Denmark, is processing 2,041 line miles of reflection seismic data shot on the West Greenland shelf in August and September 1900. Sixty-fold stacks and migrations will be obtained.

Total field magnetic data were also recorded during the survey, known as project Syd Vest Seis.

Early work is under way to kick off the multicompany Kanumas seismic acquisition project, proposed in 1986, during 1991.

Meanwhile, the Mineral Resources Administration for Greenland (MRA), Copenhagen, said the Danish and Greenland governments aim to sweeten Greenland's exploration regulations prior to making areas available.

KANUMAS PROJECT

The Kanumas project, which runs through 1995, entails collection, processing, and interpretation of about 8,389 line miles of data off Greenland.

The regional seismic is to be shot off northwestern Greenland between 76 45 and 70 30 N. Lat. and off northeastern Greenland between 79 30 and 68 00.

Participating are affiliates of British Petroleum, Den norske stats oljeselskap a.s., Esso Exploration, Japan National Oil Corp., Shell, and Texaco.

Nunaoil AS, Copenhagen, the Greenland-Danish company, is operator for the group and has been granted a prospecting license to carry out the project.

GGU will act as principal geological and geophysical project advisor, supervise field work, processing and interpretation of geophysical data, and geological reporting associated with the project.

Negotiations are under way with contractors for operations in September and October 1991. Field work did hot begin in 1990 because no suitable vessel of the required high ice class could be mobilized in time.

WHAT'S PLANNED

Object of the survey, with 40 km line spacing, is to gain overviews of Greenland's general offshore potential, whether indications of the presence of sedimentary basins are correct, and which of the basins are large enough and suitably structured to host hydrocarbon reserves.

Kanumas stands for Kalaallit Nunaat Marine Seismic. Kalaallit Nunaat is the Greenlandic name for Greenland.

Data acquisition is to take place during four ship seasons, one off Northwest Greenland in Melville Bugt and three off Northeast Greenland.

The project will include supplementary lines as far south as 68' N. in areas missed by the North Atlantic D survey in the early 1980s because of ice conditions.

Due to the unpredictability of ice conditions off eastern Greenland, no detailed plan or priority for the order in which the different parts of the shelf will be surveyed was made.

The final decision as to where the seismic vessel should be sent each season is to be made about 1 month before the start of each cruise.

OIL, GAS POTENTIAL

Hans Christian Larsen and T.C.R. Pulvertaft summarized in GGU's 1990 annual report the reasons for believing the potential of the areas to be surveyed.

A very strong negative gravity anomaly has been recorded in an elongate area stretching south-southeast from Kap York in Melville Bugt of Northwest Greenland, they wrote. A negative magnetic anomaly covers about the same area.

Together these suggest a sedimentary basin as thick as 8 km in the area.

An oil seep on the sea floor on the opposite side of Baffin Bay and the occurrence of potential oil source rocks onshore West Greenland on the Nugssuaq and Svartenhuk peninsulas are encouraging signs that source rocks might be found in such a basin (Fig. 1).

The Eastmar aeromagnetic survey revealed the presence on the Northeast Greenland shelf of elongate areas with depth to magnetic basement up to more than 8 km.

The areas are probably sedimentary basins, although the sediments could be any age from Late Proterozoic to Tertiary.

However, when the continents have been restored to their position prior to the opening of the North Atlantic and Greenland Sea, the Northeast Greenland shelf lies on line with the oil producing areas of the North Sea and adjacent to highly prospective areas on the Norwegian shelf.

Furthermore, good source rocks occur at several stratigraphic levels onshore Northeast Greenland. Expectations for the Northeast Greenland shelf are, therefore, high, wrote Larsen and Pulvertaft.

OTHER SEISMIC PROJECT

Beyond the grounds for optimism about the hydrocarbon potential of Melville Bugt and offshore Northeast Greenland, ice conditions are severe.

Detailed seismic prospecting is outside what can be achieved with existing technology, and hydrocarbon exploitation in these areas cannot be expected during the first 20 years or even longer in the case of Northeast Greenland.

Therefore, GGU is continuing investigations in the less demanding West Greenland shelf (Fig. 2).

Project Syd Vest Seis was carried out during summer 1990, financed jointly by GGU and the MRA.

Project Vest Sokkel in 1988 showed several areas off southern West Greenland with the potential to contain hydrocarbons, but more seismic data was needed to refine understanding. Once processed the data will be interpreted by GGU and available for sale.

Objectives of the project are to:

• Investigate areas of poor data coverage south of 64 20 N.

• Improve the understanding of the structural development of the Kangamiut ridge and areas west of it.

• Investigate the area south of the Kangamiut ridge and west of the Nukik wells that may contain interesting fault blocks.

• Examine the nature of the possibly compressional structures around 1 Ikermiut.

• Examine the deep sedimentary section between 67 and 68 N.

• Attempt to penetrate with seismic energy the Tertiary basalts west and southwest of Disko Bugt in order to examine whether there are sediments and structures below them.

PROSPECTIVITY

About 85% of Greenland's land area is covered by inland ice and is not at present regarded as a potential exploration area.

It appears the total area of Greenland's land and offshore sedimentary basins may be more than 1 million sq km.

Data GGU has collected the past 20 years led to a preliminary assessment that about one third of that area may be prospective for crude oil and natural gas.

A group led by ARCO Greenland relinquished its exclusive hydrocarbon exploration concession in the Upper Paleozoic-Mesozoic basin in Jameson Land of east central Greenland at yearend 1990.

GGU has delivered to MRA an independent assessment of the Jameson Land basin on the basis of an interpretation of the 1,117 line miles of reflection seismic data acquired by the concessionaire and all other GGU and company information.

The results of the assessment will be available to the industry in early summer 1991.

Besides the Kanumas project, Halliburton Geophysical Services Inc. in late 1990 acquired 1,189 line miles of speculative seismic data off southern West Greenland under a nonexclusive license. The program is a supplement to GGU's Syd Vest Seis project.

LOCAL POTENTIAL

Here is a rundown of oil and gas potential and activities in various parts of Greenland from GGU's annual report:

North Greenland: GGU mapped the Franklinian basin north of 81 N. in 1978-80 and 1984-85, conducted source rock and laboratory studies in 1984-85 and summarized the results (OGJ, Feb. 12, 1990, p. 56).

East Greenland basins north of Jameson land: An oil geological project began in 1986 based on field and laboratory studies in the Upper Paleozoic and Mesozoic basins between 72 and 78 N. in Northeast Greenland. Part of the effort was intended to be of value in the Kanumas reconnaissance seismic survey starting in 1991.

Some 27 reports and publications are encouraging with regard to implications for the prospectivity of the offshore region and indicate that about 6,000 sq km in the easternmost part of the onshore area may be prospective.

Southern West Greenland shelf. About 40,000 line km of reflection seismic data were acquired during 1970-77. Five exploratory wells were drilled in 1976-77, all into basement or volcanic highs, and all were dry. Reinterpretation of the old seismic data indicates that all the drilled prospects were defective as hydrocarbon traps.

Reinterpretation of the old data also revealed pre-Tertiary sequences up to more than 2 km thick, while only one well substantially penetrated pre-Tertiary sequences.

Onshore West Greenland: The Upper Cretaceous-Lower Tertiary sediments exposed between 69 and 72 N. in West Greenland are not considered prospective. However, they are the only sediments exposed anywhere in West Greenland that can provide clues to the interpretation of the offshore geology and include the only marine sediments of this age exposed anywhere in the Labrador Sea-Baffin Bay region.

GGU carried out oil geological investigations of the sediments in the 1970s. It is planning to start in 1991 a two season campaign in the Disko-Nugssuaq-Svartenhuk area to obtain more detailed knowledge of relevant onshore geology, in particular for a more precise palyno-stratigraphy of the sediments and an up to date study of potential source rocks and the factors that govern their distribution and lateral variation.

Copyright 1991 Oil & Gas Journal. All Rights Reserved.