The South Kara Sea platform is a continuation of the West Siberian platform. Resting on Baykalid basement are Paleozoic sedimentary rocks, which were weakly deformed during Late Hercynian and Early Kimmerian phases of folding. Next overlying are 5-8 km of platform sediments, which range in age from Triassic to Recent.
Extending in a northwest direction in the west-central part of Yamal Peninsula is the Nurmin mega-swell, where such large gas-condensate fields as Bovanenko, Kharasavey, and Kruzenshternov have been delineated.
Geophysical surveys of the South Kara Sea Shelf and deep wells along the coast of Yamal Peninsula suggest that the Jurassic and Cretaceous pay zones of the Nurmin mega-swell and other onshore highs extend offshore onto the South Kara Sea Shelf. Rusanov mega-swell extends some 200 km north-south in the central part of the South Kara Sea. It appears to be a continuation of the Nurmin mega-swell. Rusanov field has been discovered at the north end of this swell, and Leningrad field toward the south end.
Rusanov high has an area of 1500 sq km. Two wells have been drilled there; their depths are 2550 and 2373 m, and both have yielded up to 600,000 cu m (21 MM cf) of gas per day from Aptian-Albian- Cenomanian strata. Twelve gas-bearing sand-silt strata with good seals were penetrated by well 2. Leningrad high has an area of 1700 sq km, and there geophysical logs show not less than ten gas-bearing strata. The gas of both these fields is methane, sulfur-free, and carries condensate with density of 0.761-0,772. These fields have not yet been delineated. It is possible that some of the pools extend continuously over both areas as a single pool and include the Severo-Leningrad high also. Resources of Rusanov and Leningrad fields are assessed at 9 trillion cu m (315 tcf) of gas.
In addition to Rusanov mega-swell four other mega-swells of different trend have been outlined. The largest of these is the Vikulov, which extends 350 km offshore along the east of Novaya Zemlya. More than 60 highs have now been identified in the South Kara Sea basin.
Discovery of gigantic gas resources in the South Kara Sea basin indicates that this feature is gas-prone at least for the Cretaceous and Upper Jurassic section. The Bazhenov and lower-occurring Jurassic-Triassic section may be oil-prone.
Each of the unexplored mega-swells of the South Kara Sea basin may contain 2-4 trillion cu m (70-140 tcf) or more of gas. Their resources are assessed at 20-25 trillion cu m (700-875 tcf). Adding this to the resources of Rusanov and Leningrad fields the total comes to 30-35 trillion cu m (1050-1225 tcf) of gas. (Taken from Nikishin and Rovnin, 2000; digested in Petroleum Geology, vol. 35, no. 2, 2001, two maps and two cross sections; in preparation)
Comment: A buried ridge extends from the north end of Novaya Zemlya southeastward to the west end of Taymyr Peninsula. I think that strat traps on the flanks of this ridge may contain huge oil deposits - if they have not been flushed out by later migrating gas. - JC Copyright 2000 James Clarke. You are encouraged to print out this News Letter and to forward it to others. Earlier News Letters are available at: http://geocities.com/internetgeology/ Internet Geology News Letter is published by e-mail at no charge in the interest of our science. To receive this publication please send your e-mail address to: jamesclarke@erols.com