Unconventional Oil Resources in the Mature Source Rocks Formation

Nikolai Lopatin¹, N.A. Malyshev², N.N. Kosenkova², and Tamara Emets^1
1VNIIgeosystems, Moscow, Russia
²"NC-Rosneft", Moscow, Russia

THE PRESENTATION AIM: To present the geological model of oil accumulations origin into siliceous black shale formation (“in situ”) on the mature stage of HC's generation and Cenozoic faulting activities.
THE PROCEDURES: Rock-Eval analyses were used for source rock characterization, and more than 2,200 core samples of the Bazhenov Formation shales were studied. Analytical techniques applied to oils and extracts from the Bazhenov Formation included GC, GC-MS and stable isotope MS. The computer programmes “Basin-Mod” and “Petroleum System Play” were used for geochemical modelling.
THE SUBJECT OF STUDY: The siliceous Bazhenov black shale Formation (J₃³ volgian stage) is an oil-prone classical source rocks unit which responsible for contain oil pools in unconventional self-sourced reservoirs. The study area included Surgut and Krasnoleninsky arches, Khanty-Mansiisk megatrough (s=80000 km²).
RESULTS: Faulting and fracturing were common in Eocene to Holocene time in conjugate zone between tectonic megastructures: Surgut and Njalin; Krasnoleninsk and Khanty-Mansiysk. The corresponding effects of faulting are macrofractures and local increase of thermal maturity of the Bazhenov‘s kerogen. Reservoirs quality increases rapidly in faulting zones. Reservoir zones are generally small and are located along fault plane. Primary oil migration was focused along fracture networks adjacent to the fault zones. Oil charging took place in the Tertiary and oil generation and expulsion in the Bazhenov Formation led to overpressuring. 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 #90072 © 2007 AAPG and AAPG European Region Conference, Athens, Greece