Title: Reservoir Geology of Fangst Group (Middle Jurassic), Heidrun Field, Offshore Mid-Norway
Abstract: Heidrun field, the largest oil discovery in the mid-Norway area known as Haltenbanken, contains an estimated 755 million recoverable bbl of oil and more than 1 tcf of gas. The reserves are contained mostly in two clastic sequences: the Middle Jurassic Fangst Group (described in this paper) and the Lower Jurassic Tilje Formation. Highly favorable reservoir characteristics in the Fangst will result in the bulk of the production coming from that unit. The Fangst tested at rates of up to 31 million standard ft3 of gas (890,000 m3) per day and 15,491 BOPD in the discovery and subsequent appraisal wells. The Fangst sandstones were deposited during a lowstand of global sea level, also marked by deposition of the Brent Group in the North Sea. The Fangst Group can be divided into four clearly recognizable stratigraphic units that serve as basic reservoir units for modeling purposes. In ascending stratigraphic order, these are F1, a coarsening-upward sequence deposited on a tidally dominated shallow marine shelf; F2, a coarsening-upward sequence deposited on a wave-dominated shallow marine shelf that culminated in upper shoreface deposition; F3, a coarsening-upward sequence deposited in deeper water on a marine shelf; and F4, a fluvial sequence. The Fangst Group consists almost entirely of sandstone, with only a thin shale occurring at the base of F3. Fangst sandstones are largely unaffected by diagenesis. Sandstone permeability is largely controlled by depositional factors such as grain size and detrital clay content. Porosities and permeabilities are extremely high. Porosities commonly exceed 30% and permeabilities exceed 500 md.
Publication Year: 1989
Publication Date: 1989-01-01
Language: en
Type: article
Indexed In: ['crossref']
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Cited By Count: 29
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