Statoil Petroleum AS, operator of the Gina Krog Unit, has completed the drilling of wildcat well 15/6-13 and appraisal wells 15/6-13 A and 15/6-13 B. The wells were drilled about 250 kilometres west of Stavanger and directly northeast of the Gina Krog field, in the North Sea, offshore Norway.
The objective of well 15/6-13 was to prove commercial petroleum volumes in Middle Jurassic reservoir rocks (the Hugin formation), acquire sufficient data to avoid further delineation, investigate the size of the discovery, the properties and continuity of the reservoir rocks, as well as determine the petroleum properties.
The objective of sidetracks 15/6-13 A and 15/6-13 B was to delineate the discovery as regards the likelihood of deeper oil and shallower gas on the structure.
15/6-13 has two separate oil columns, 13 and 3 metres of which are in sandstone with moderate to good reservoir properties in the Hugin formation and upper part of the Sleipner formation. The oil/water contact was not encountered.
15/6-13 A encountered seven and nine metres of sandstone with moderate reservoir quality in the Hugin and Sleipner formations, both aquiferous. The aquiferous sandstone in the Hugin formation is presumed to be in pressure communication with the oil zone in 15/6-13.
15/6-13 B shows an overall gas column of about 60 metres, of which 7 metres are in sandstone with moderate reservoir quality in the Hugin formation and 26 metres in sandstone with moderate reservoir properties in the Sleipner formation. The underlying sandstone in the Skagerrak formation is tight and aquiferous.
For the discovery as a whole, the overall oil and gas column totals about 300 metres, 150 metres for each. Preliminary calculations of the size of the discovery are between one and two million standard cubic meters (Sm3) of recoverable oil equivalents in the Hugin formation, whereas calculations of any additional volumes from the Sleipner formation will require additional assessment for further clarification.
None of the wells were formation-tested, but comprehensive data collection and sampling was conducted.
The licensees in the Gina Krog Unit will assess the discovery further with a view toward possible development and tieback to the Gina Krog field.
Wells 15/6-13, 15/6-13 A and 15/6-13 B were drilled to a measured depth of 3577, 3925 and 3773 metres, respectively, and vertical depths of 3552, 3716 and 3447 metres below the sea surface. They were all terminated in the Skagerrak formation in the Upper Triassic. The wells have been permanently plugged and abandoned. Water depth at the site is 114 metres.
The wells were drilled by the Songa Trym drilling rig, which will now move on to drill another Statoil-operated well on the UK shelf.