Base data

24.06.2010

Three-dimensional seismic surveys from Troms II have helped to enhance geological understanding.

Three-dimensional seismic surveys from Troms II
have helped to enhance geological understanding.



The seismic data for the areas evaluated vary in both scope and quality. Nordland VI and the Egga Edge are the areas with the best data coverage from before. Following new seismic surveys in 2007-09, both Nordland VII and Troms II are satisfactorily covered. More seismic data are needed from the West Fjord and the unopened part of Nordland V to secure a good resource assessment and definition of prospects.

A total of 14 303 kilometres of 2D seismic were shot by the NPD during 2007-09 in Nordland VII and Troms II. In addition, 2 760 square kilometres of 3D seismic data were gathered. Figure 8 shows where these surveys were conducted. The NPD has also gathered gravimetric and magnetic data. During the autumn of 2009, the NPD collected rock samples in the Bleik Deep just west of Andøya in Nordland VII. The aim was to collect information to determine the age and condition of the rocks.

Both the NPD and other players had gathered 2D seismic data in the surveyed areas before. Six scientific wells have also been drilled, along with an exploration well (6710/10-1) in Nordland VI.

All the wells drilled in and around the areas covered by this study have been used in the evaluation. Scientific drilling has been conducted in Nordland V/VI/VII and Troms II.

Information which can be used in assessing the continental shelf geology is also available on land in Vesterålen. Older Jurassic and Cretaceous sediments have been preserved in a small area on Andøya. This is an important area, which has been subject earlier to detailed studies.

In areas with many scientific and exploration wells, a good basis exists for estimating possible oil and/or gas resources. Important information includes the thickness of reservoir sands, their porosity and their hydrocarbon saturation (some water will always be present in the pores).

A good understanding of the main geological features is fundamental in describing opportunities for finding oil and gas in an area. Where no petroleum activity has occurred, such an understanding must build on seismic interpretations collated with data and knowledge from known petroleum provinces. Geological conditions in the eastern part of Nordland VI, for instance, can be viewed as an extension of the prospective areas further south. The eastern part of Troms II is comparable with the southern Barents Sea. Nordland VII and the southern part of Troms II have their own special geological history, but with elements which can be recognised to both north and south. Based on such an assessment, the uncertainty will be greater in this intermediate area than in the others described.

Once seismic data have been gathered, they are processed. A hard seabed and little water depth in parts of Nordland VII complicate processing of the seismic data. The NPD regards the quality of the raw data gathered as good. However, it remains possible to process this information even further to gain greater knowledge of the area geology.

 

Figure 8. Seismic surveys conducted in 2007-09.

Figure 8. Seismic surveys conducted in 2007-09.

 

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