The Snorre Field: A Major Field in the Northern North Sea
The Snorre field is located in the northern North Sea and belongs to the prolific hydrocarbon province on the western margin of the Viking graben, which contains the Brent, Statfjord, and Gullfaks fields. The Snorre field was discovered in 1979. It has two main reservoirs—the Triassic Lunde Formation and the Triassic-Jurassic Statfjord Formation. Each of these reservoirs consists of a network of fluvial sand bodies in a mudstone matrix.
The reservoir properties range from fair to very good. Typical test permeabilities are 2000 md in the upper part of the Statfjord Formation and 125 to 380 md in the underlying units.
The Snorre field contains 490 million standard m3 (3.1 billion bbl) of undersaturated oil in place, of which approximately 75% occurs in the Lunde Formation. The oil-water contact varies from 2561 m (8400 ft) on the crest to 2599 m (8530 ft) in the western region.
This field is a structural/stratigraphic trap formed by westward tilting and erosion of a major fault block. Both reservoirs are truncated by the Kimmerian unconformity and overlain by Jurassic and Cretaceous shales. Organic-rich Upper Jurassic shales constitute the major source rock.
The Snorre field will undergo a two-phase development. In phase 1, a tension leg platform (TLP) will be located in the southwestern part of the field. Production will start in 1992 with six wells predrilled from a template beneath the TLP. Additional TLP wells and another subsea template will complete phase 1. For phase 2, there are two different options—either relocating the TLP to the northern part of the field or leaving it in its original position and adding two more subsea templates.
The field development plan (FDP) calls for water injection and includes 73% of the oil in place. On this basis, it is estimated that 119 to 122 million standard m3 (750 to 770 million bbl) of oil will be recovered, depending on which phase 2 alternative (TLP relocation or subsea extension) is chosen. Studies aimed at increasing field production, by developing portions of the oil that are not included in the current plan, are presently being performed.