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Delineation of the Hanz field and dry wildcat well in the North Sea

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Oilfield Technology,

The wells were drilled about 14 km north of the Ivar Aasen field in the central part of the North Sea and 180 km northwest of Stavanger.

The Hanz field was proven in Upper Jurassic reservoir rocks (Intra-Draupne formation sandstones) in 1997. Prior to the drilling of wells 25/10-16 S, A and B, the operator’s resource estimate for the discovery was between 1.9 and 3.0 million Sm3 of recoverable oil and between 0.3 and 0.4 billion Sm3 of recoverable gas.

The objective of the wells on the Hanz field was to delineate the field, investigate potential additional resources in underlying Middle Jurassic reservoir rocks (the Hugin formation), reduce the uncertainty as regards the extent of the reservoir sandstones and thus lower uncertainty for the field’s estimated resources.

The primary exploration target for wildcat well 25/10-16 B was to prove petroleum in Upper Jurassic sandstones (the Intra-Draupne formation), while the secondary exploration target was to investigate the underlying Hugin formation. The prospect was partially situated in production licence 915, just to the southeast of production licence 028 B.

Appraisal well 25/10-16 S encountered an approximate 30 m gas column and a 30 m oil column in the Draupne formation, of which the effective reservoir totalled about 20 m in sandstone layers, mainly with good reservoir quality. The oil/water contact was not encountered. An aquiferous sandstone layer, about 15 m thick, was encountered in the underlying Hugin formation, with moderate to good reservoir quality.

In appraisal well 25/10-16 A, there is an approximately 15 m gas column in the Hugin formation, in sandstone with moderate to good reservoir quality. The gas/water contact was proven. The overlying Draupne formation contains a total of about 10 m of tight and partially tight sandstone layers.

Wildcat well 25/10-16 B encountered a total of about 15 m of tight and partially tight sandstone layers in the Draupne formation. Approximately ten m of aquiferous sandstone with moderate to good reservoir quality was encountered in the Hugin formation. The well is dry.

In appraisal well 25/10-16 C, there is approximately 15 metres of aquiferous sandstone in the Hugin formation, with moderate to good reservoir quality. In the overlying Draupne formation there is a total of about five m of tight and partially tight sandstone layers. The well is dry.

Preliminary estimates of the size of the field lie within the range of uncertainty for the resource estimate before the wells were drilled. The Hanz field is included in the Ivar Aasen field’s plan for development and operation (PDO).

The wells were not formation-tested, but extensive volumes of data and samples have been acquired.

These are the four first exploration wells in production licence 028 B.

Appraisal wells 25/10-16 S, A and C were drilled to respective vertical depths of 2643, 2496 and 2626 m and respective measured depths of 2765, 3660 and 4382 m below the sea surface. Wildcat well 25/10-16 B was drilled to a vertical depth of 2574 m and a measured depth of 4870 m below the sea surface. All wells were terminated in the Skagerrak formation in the Upper Triassic.

Water depth is 117 m. The wells have been permanently plugged and abandoned. The wells were drilled by the Maersk Intrepid drilling facility, which will now drill development wells on the Martin Linge field in the North Sea, where Equinor Energy AS is the operator.

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