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.
Figures & Tables
The success of Memoir 14 and the worldwide interest shown for data on giant fields prompted AAPG to schedule a symposium on giant fields at the end of each subsequent decade. The 1968-78 symposium was held in Houston, Texas, April 1-4, 1979, and the papers were published in AAPG Memoir 30, December 1980.
The Stavanger Conference "Giant Oil and Gas Fields of the Decade: 1978-1988" was held in Stavanger, Norway, September 9-12, 1990, and is a continuation of the Giants of the Decade series.
Scientific studies and projections of future world energy demand indicate that although alternative-energy fuel sources must be actively pursued and developed, there also must be adequate petroleum supplies to bridge the gap. For the international petroleum industry, the years covered by this conference, 1978-88, were complex. They were years of boom and bust. The world's energy consciousness was boosted sharply by the effects of the 1979 Iranian revolution and the resulting embargo, which sent world oil prices to record heights. Global petroleum exploration soon surged, leading to the industry's all-time drilling high in 1981. Then came the oil price collapse in 1985, and the following years were characterized by falling oil prices and drastic budget cuts for exploration and development.
Although exploration dropped sharply during the latter part of the decade, there was a steady flow of giant oil and gas field discoveries. Using the giant field designation criteria of 500 million bbl of oil recoverable for fields in Asiatic Russia, North Africa, and the Middle East,