The Oseberg field is located in the Norwegian North Sea in blocks 30/6 and 30/9, approximately 140 km northwest of Bergen, Norway. The field came onstream in December 1988.
The Oseberg field comprises three major eastward-tilted fault blocks called Alpha, Gamma, and Alpha North. The hydrocarbons are contained in the sandstones of the deltaic Middle Jurassic Brent Group. The Brent Group exhibits excellent reservoir properties, including porosities from 20 to 25% and permeabilities ranging up to several darcys. The gross thickness of Brent ranges mainly between 50 and 190 m (Table 1). The maximum extension of the field is 26 km, and the maximum width is about 6 km. The structural dip is normally 6 to 10° east-northeast.
Gas caps are present in all structures. The Alpha structure has a vertical gas column of 380 m and an oil column of 210 m, for a total hydrocarbon column of about 600 m.
Reservoir engineering studies have shown that a greater ultimate volume of oil can be recovered by gas flooding than by water-flooding. Consequently, pressure maintenance by gas injection has been chosen as the production mechanism for the Alpha and Gamma structures. An adequate supply of gas for injection can be obtained only by importation of large quantities from the huge Troll field by means of a 48-km-long pipeline. The Alpha North structure will be produced mainly by water flooding.
On the Oseberg field itself, the development comprises a field center in the southern part of the field (onstream), a production platform in the northern part (in construction), and three subsea wells.
The current estimates of field reserves are 231.6 million standard m3 of oil and 92 billion standard m3 of gas.
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,