--> Abstract: Geochemical Exploration for Oil in Self-Sourced Reservoirs, West Siberian Basin, by Nikolai V. Lopatin, Iosif L. Levinzon, Tamara P. Emets, and Evgeny A. Romanov; #90078 (2008)

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Geochemical Exploration for Oil in Self-Sourced Reservoirs, West Siberian Basin

Nikolai V. Lopatin1, Iosif L. Levinzon2, Tamara P. Emets3, and Evgeny A. Romanov4
1Rosnedra, VNIIgeosystem, Moscow, Russian Federation
2Novatek, Moscow, Russian Federation
3VNIIgeosystem, Moscow, Russian Federation
4Surgutneftegas, Tuymen, Russian Federation

General outline about unconventional oil accumulations in self-sourced fine-grained siliceous reservoirs, and, in detail, the Bazhenov black shale formation (J3) in the West Siberian Basin, trap tipe-locality, overpressure distribution, and striking features for exploration.

The Geochemical relevance based on the 2370 Rock-Eval analysis of the Bazhenov core samples, GC, GC-MS and stable isotope MS oils and rock extracts, 1D Basin Modeling, Petroleum System plays for the 7th mini-basins, and exploration risk analysis.

The deep-marine, principally siliceous Bazhenov Shale with oil-prone kerogen type II is a very rich source rocks: TOC=7-32 %, S1=5.5-37.2, S2=60-230 mg HC/g rock, HI=500-980 and OI=0-7 mg HC/g TOC. These shales contain the unconventional oil pools in siliceous self-sourced reservoir (“in situ”). Unusual trapping mechanism based on fracturing type of siliceous reservoir, Cenozoic timing of oil charge, short paths of primary migration on the panel of faults and fracture geometry, small type-locality but distributed often along faults, oil generation rate exceeds expulsion, absence of basal oil/water contact, and high overpressure (2.0-2.3). It defines non-traditional exploration and production workflows. Probability of exploration success is about 0.32 and “dry” hole is 0.35.

This simple geological model is proposed to explain the trapping mechanism and non-traditional exploration workflows for unconventional oil pools in the Bazhenov Shale. Traps type of locality needs to be extensively explored. Exploration risk in the self-sourced Bazhenov Formation reservoirs mainly relates to seismically-defined regional faults or to transverse faults.

 

AAPG Search and Discovery Article #90078©2008 AAPG Annual Convention, San Antonio, Texas