Petroleum Systems of the Western Yamal Shelf

Grigoriy Ulyanov, Tamara A. Kirjukhina, Antonina Stoupakova, and Anna Kunitsina
Lomonosov Moscow State University, Moscow, Russia.

The Western Yamal shelf is one of the most perspective areas for exploratoin of hydrocarbon fields with different qualitative composition.Leningradskoye and Rusanovskoye fields with proven commercial petroleum potential of Jurassic and Cretaceous sediments,discovered in the offshore area, are unique and encourage assumptions on vast petroleum potential of this area. The current status of petroleum geology oriented to exploration of new petroleum regions and to additional exploratoin of the old ones, need modern approaches to interpretation of geologic-geochemical data.Integrated approach to interpretation of the accumulated data assumes treating of the oil-and-gas bearing basins as series of sequential in time hydrocarbon systems with their own cycle of oil-and-gas generation, accumulation and preservation of HCs. There are several petroleum systems in the Yamal sediments’ cross-section, which are characterized by their own cycle of petroleum generation and accumulation. Marking is based upon presence of one or several source rocks in a section and the under- and overlying seal beds causing processes of generation and accumulation of hydrocarbons. Petroleum systems are characterized by various exploration maturity, so among them are allocated prospects - Paleozoic and Triassic, and established - Lower-Middle Jurassic, Upper Jurassic - Lower Cretaceous and Albian-Cenomanian. Lower-Middle Jurassic and Upper Jurassic -Lower Cretaceous petroleum systems due to their source rock features generate both oil and gas HCs. Upper Cretaceous petroleum system generates mainly gas HCs. There are two established petroleum systems in Mezo-Cenozoic deposits of the Western Yamal shelf. These are: Albian-Cenomanian and Lower Cretaceous. Lower-Middle Jurassic petroleum system is predictive, due to analogies in a geological structure of offshore and onshore parts of the area and could also be the most perspective for exploration of condensate, gas and gas-oil deposits in the South Kara depression. Oil deposits in this area are expected to be rare enough and most probably will not be of commercial value. In the western part of Southern Kara Depression Upper Cretaceous hydrocarbon system is of low potential due to sharp reduction of the sediments and main potential can be attributed to Lower-Middle Jurassic and Upper Jurassic-Lower Cretaceous hydrocarbon systems, where development of oil deposits is assumed, and gas or gas-condensate deposits will be of secondary value.

AAPG Search and Discover Article #90096©2009 AAPG 3-P Arctic Conference and Exhibition, Moscow, Russia