Supergiant Shtokmanovskoye gas field, in the Barents Sea, is in the western part of Russia's vast arctic continental shelf.
The field lies almost 1,200 km east of the Snøhvit complex off northern Norway.
Russian authors have written that 2 million sq km of their arctic shelf are favorable for oil and gas. Assessed resources of this shelf are placed at not less than 700 billion bbl of oil equivalent.
Shtokmanovskoye, discovered in 1988, has difficult economics despite its size. Development will involve a $10-20 billion, three-platform project with first gas produced in 2008.
With reserves of about 3.2 trillion cu m, the field is in 300 m of water and has a reservoir of Jurassic age some 4 km subsea (OGJ Online, June 7, 2000).
Off Russia, the Ludlov saddle, sometimes called the Barents Sea arch, separates the South Barents and North Barents depressions, the Russian authors wrote in Geologiya Nefti i Gaza in 1999. The Petroleum Geology quarterly, edited by James Clarke, Great Falls, Va., reprinted the article in English. The authors are B.A. Nikitin, L.I. Rovnin, Yu. K. Burlin, and B.A. Sokolov.
The Ludlov saddle (Fig. 1), the authors continued, "measures 200 by 300 km and has an amplitude of 500 m on the top of the Upper Jurassic black clays. Both depressions along with the intervening uplift zone are combined into the East Barents mega-downwarp (sineklize). This mega-downwarp is a single large oil-gas basin of long development, within which are large kitchens and zones of hydrocarbon accumulation.
"On the Ludlov saddle is the Ludlov gas-condensate field, with pools in Jurassic clastics, and on the south the Ledov field. This entire zone of oil-gas accumulation has an area of 60,000 sq km, and presence of several other oil-gas horizons are possible here to depths of 6 km," the article said.
"Seismic surveys to the north of the Barents Sea arch have disclosed a large uplifted zone of Triassic-Jurassic and Cretaceous rocks, which measures 100 by 100 km. Within it has been recognized the Lunin high as well as other possible structures.
"The Lunin zone is also regarded as a large zone of oil-gas accumulation, toward which the Jurassic pays of Shtokmanov field trend. The Triassic is predicted to be productive there also. Gas resources of a field on the Lunin high are assessed as possibly not less than 3 trillion cu m (105 tcf)."
Other targets
Russia also anticipates discovery of significant oil and gas in the next province to the east.
"The Admiralty swell is highly favorable for oil and gas," the article noted. "This feature extends almost 400 km along the west side of Novaya Zamlya and bounds the Barents Sea mega-downwarp on its east. One well has been drilled on this feature; it penetrated Triassic sediments which showed signs of oil.
"Three large highs are recognized on this swell: Krestov (30 by 40 km), Admiralty (60 by 50 km), and Pakhtusov (60 by 40 km). Devonian rocks are expected here at depth of 6-8 km.
"The main stratigraphic complex on the swell [are] Permo-Triassic rocks. Sufficient geological information is already available for predicting discovery of large oil and gas fields here in the first half of the 21st century. Ice conditions will be a problem, however."
Continuing eastward, the Kara Sea shelf is a northern extension of the West Siberian oil and gas province. The South Kara depression, in the southwestern part of the Kara Sea, contains only three deep wells. The depression should contain a very large oil and gas basin as indicated by the discovery of giant gas-condensate fields in Lower and Upper Cretaceous rocks on the Yamal Peninsula coast.
The three wells discovered Rusanov and Leningrad gas-condensate fields, not yet delineated, in 50-100 m of water. The fields have more than 10 gas pays and a preliminary assessment that exceeds 280 tcf.
"In the northeast part of the Kara Sea is the North Kara depression, where crystalline basement is at depths of 12-20 km. This depression, filled with Paleozoic and Triassic rocks, also has an enormous oil-gas potential," wrote Nikitin et al. "Its geology and petroleum potential remain almost without study because of difficult natural conditions. Assessment of this basin will be possible only much later than the year 2010."
Four basins-Laptev Sea, East Siberian Sea, North Chukchi, and South Chukchi-reside in the eastern arctic off Russia, but none has received much study.
