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The AAPG/Datapages Combined Publications Database

AAPG Bulletin


Volume: 65 (1981)

Issue: 5. (May)

First Page: 984

Last Page: 985

Title: Seismic Interpretation of Statvik Field, Norway--3-Dimensional Study of Subunconformity Trap: ABSTRACT

Author(s): G. T. Saeland, G. S. Simpson

Article Type: Meeting abstract


The Statvik field is located in Norwegian North Sea block 34/10. Initial exploration was based on the interpretation of a one-kilometer 2-D migrated seismic grid. In 1979, at a relatively early stage in the exploration phase, it was decided that better quality data were needed to adequately map the structurally complex, highly faulted area, and to guide further delineation drilling. A 3-D seismic survey was therefore shot, covering the whole structure.

It is obvious from a comparison of individual lines that the 3-D data is of significantly higher quality than the 2-D data. Furthermore, the extremely dense grid of lines makes it possible to develop a more accurate and complete structural and stratigraphic interpretation.

Specifically, the 3-D data made it possible to map more accurately the dip and the subcrop of the subunconformity strata. The early geologic model had the Jurassic reservoir sands dipping steeply westward over the whole of the structure. This implied extensive erosion of the main reservoir sands toward the east. With the 3-D seismic data, however, we were

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able to recognize and map much gentler dips in the eastern part of the structure. The result of this is to move the mapped subcrop of the reservoir sands much farther eastward, thus extending the eastern limit of the field considerably.

Based on this 3-D interpretation, three successful oil wells have been drilled. These are located in parts of the field that could not be accurately mapped on the basis of the 2-D seismic data, because of its poor quality. This has increased the estimate of the field's reserves such that Statoil were able to declare the field commercial in late 1980.

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Copyright 1997 American Association of Petroleum Geologists