--> ABSTRACT: Petroleum Systems in Deep Formations of the Northern Part of West Siberia on the Basin Modeling Basis, by C. Leonard, J. Leonard, N. Nemchenko, T. Nemchenko, A. Rovenskaya, and S. Girshgorn; #90906(2001)

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C. Leonard1, J. Leonard1, N. Nemchenko2, T. Nemchenko2, A. Rovenskaya3, and S. Girshgorn3

1Platte River Associates, Denver, Colorado
2Russian State Gubkin Oil & Gas University, Moscow, RF
3State Scientific Center VNIIGeosystem, Moscow, RF

ABSTRACT: Petroleum Systems in Deep Formations of the Northern Part of West Siberia on the Basin Modeling Basis

Northern West Siberia is one of the largest gas-producing regions playing a significant role in the fuel and energy balance of the world. This region firmly holds a world lead in the concentration of gas reserves and the number of unique, giant and large gas fields. As to January 1, 1999 the estimated reserves of gas are as much as 100 trillion m3 and the proved reserves of commercial categories – 50 trillions m3. This is a gas bearing pool of the world.

Among gas fields comprising the unique reserves are as follows: Urengoy – 9.5 trln m3, Yamburg – 6.0 trln m3, Bovanenkov – 5.0 trln m3, Kharasavey – 1.5 trln m3, North Urengoy – 1.0 trln m3, Medvezhie – 1.0 trln m3, Kruzenshtern – 1.5 trln m3, South Russkoe – 1.0 trln m3, South Tambey – 1.5 trln m3, Kharampur – 0.95 trln m3, Malygin – 0.7 trln m3, Utrennee – 0.7 trln m3, Yamsavey – 1.0 trln m3, and Komsomolskoe – 0.7 trln m3.

All the unique and giant gas accumulations identified within the limits of the thick (up to 2000 m in thickness) Cretaceous (Neocomian-Cenomanian) oil and gas bearing complex are located in its upper section – in the Cenomanian deposits, at the depths from 600 to 1200 m immediately beneath the regional Turonian-Paleogene clay cap rocks. These accumulations are confined by the arc sections of large -size (of 500 to 4000 km2), high amplitude (100-200 m and more) local rises, particularly, by firstorder structures (Nizhnepurovsk, Medvezhiy, and Yamburg mega -ridges).

The principal deposits of gas-condensate and gas-condensate and oil are located in the middle and lower parts of the complex in Aptian and Neocomian sediments beneath subregional and zonal cap rocks. Gas-condensate deposits have also been discovered in the Achimovskaya sequence (Valanginian) and the sediments of the Jurassic complex.

The further increase of commercial hydrocarbon resources will be tied to the development of ultra-deep horizons. These are confined to the norther n region of the West Siberian oil and gas province, where the maximum thickness of the Mesozoic- Cenozoic cover is 6-18 km. On the most part of the territory deep zones are represented by Lower Jurassic, Triassic and Paleozoic formations. These sediments have been penetrated in this area by isolated wells drilled to depths of over 4.5 km (Nadymskaya well 7; Yamburgskaya well 700; Urengoyskaya wells 264, 266, SG6).

AAPG Search and Discovery Article #90906©2001 AAPG Annual Convention, Denver, Colorado