The Jurassic Snehvit Gas Field, Hammerfest Basin, Offshore Northern Norway
The first well offshore northern Norway was drilled in 1980, and the Snøhvit field, which is the largest gas find and the first oil discovery in the area, was discovered in 1984. The Snøhvit field is in the southwest Barents Sea in the center of the Hammerfest Basin and straddles blocks 7120/6, 7121/4, and 7121/5. Water depth is approximately 300 m. The field covers 90 km2 (22,200 ac) and has a gas column of 124 m (407 ft) overlying a 14 m (46 ft) thick oil leg. This oil leg makes Snøhvit the only significant oil find on the Barents Shelf to date.
The reservoir consists of Lower to Middle Jurassic sandstones deposited in a transgressive coastal to inner shelf sequence. Three wells, each situated in a separate fault block, define the Snøhvit field. The wells have common fluid contacts. Reservoir properties are fair, with a porosity of 15% and permeability from 200 to 500 md in the main reservoir. The water saturation in the gas zone averages 10%, and varies from 3 to 26%.
A burial history involving uplift, erosion, and renewed burial during the Tertiary has influenced the distributions of oil and gas in the reservoir and the positions of the fluid contacts.
The most likely estimate of gas in place is 160 billion standard m3 (5.6 tcf), and the gas has a recovery factor of 70%. The oil in place is estimated at 73 million standard m3 (450 million bbl). Because of the thin oil leg and the areal distribution of the oil in the reservoir, it is not thought economically feasible to develop the oil with present-day technology. Various development scenarios have been studied for the Snøhvit gas, but currently there are no firm development plans.