--> ABSTRACT: The Northern West Siberian Gas-Condensate Province. Geological Features, Commercial Reserves and Origin of Gas Pools, by Nikolai V. Lopatin; #91020 (1995).

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The Northern West Siberian Gas-Condensate Province. Geological Features, Commercial Reserves and Origin of Gas Pools

Nikolai V. Lopatin

The Northern West Siberia is the first most prolific gas-producing province in a world. The principal aim of this research is to delineate gas source rocks using the gas compositional data set (>2000 analysis), new maturity measurements and quantitative modelling of basin dynamic evolution for support by numerical simulation of gas accumulation histories. Giant Gas fields arc found between the Arctic circle and Kara Sea offshore on the territory of the Yamal-Taz megasincline.

The West Sibarian gas commercial reserves exceed 52 trillion m3 and concentrate mainly in Giant and Supergiant. Most part of gas commercial reserves concentrating in the Cenomanian pools is almost pure methane. Nonhydrocarbon gas constituents have N2 -0,97% (45 analysis) and CO2 -0,15% (46). Carbon isotopic composition of Methane (^pmil, ^dgr13C vs. POB) vary between -47.02 % to 54.66%. The Aptian and Albian gases consist 94% to 96% and ^dgr13C of C1 -44.59^pmil to -41.73^pmil. The Neocomian pools characterize as fat gas with ^dgr13C of C1 -34.31^pmil to -37.73^pmil; N2 -0.73 (112) and CO2 -0.41 (115). The Tyumen formation (J1-2) contain rather seldom and small gas ccumulations, mainly, dry gas with ^dgr13C of C1 -31.40^pmil to -35.14^pmil.

The major gas accumulations genetically connect with coal type kerogen of the Pokur formation (early mature zone). Neocomian gas pools have been derived from marine offshore mudstone and Bazhenov black shales in mature zone. Lower and Middle Jurassic gas accumulations have gas-prone nonmarine sources in overmature zone.

AAPG Search and Discovery Article #91020©1995 AAPG Annual Convention, Houston, Texas, May 5-8, 1995