Unconventional Resources and Oil Accumulations of the Bajenov Suite of the West Siberia: Irregulation of the Distribution and Localization

Valyaev, Boris M.¹
(1)Oil and Gas Research Institute, Moscow, Russian Federation.

At present oil accumulations in the Bajenov deposits have been discovered in the some dozen oil-gas fields of the West Siberia. The largest accumulation is disposed on the Salym field and have been developed since 1974 year. The results of geophysic investigations, drillings and developments reveal in a number of cases the specific peculiarities of localization of the oil accumulations in the Bajenov deposits of the Salym field and other fields. Among them, the irregularities of distribution of the oil accumulations the volume of resources are the main one. The another important peculiarity is the irregularity of the oil concentration within the pools.

Structural control of these irregularities are distinctly revealed at the Salym field. The highest oil debits have been received within the submeridional belt - the zone of the deep fault on west slope of the Surgut high. Maximum anomalies of the pore pressures (with Ka=1,86) and the temperature are typical for this belt (zone). Abnormally high oil debits are conditioned by the abnormally high fracturing of reservoirs, coinciding with the zones of the increased deformation of silicious-clay deposits of the Bajenov suite (Malobalykskoe, Vostochno-Surgutskoe, Vostochno-Kalchinskoe, Tovminsko-Russkoe fields). Similar situations have been revealed in a number of fields and perspective structures of some oil and gas regions of the West Siberia. The geological section of the Bajenov suite are consist of four litotypes. The litotype, characterizing the highest concentration of the siliceous and organic matter possesses the maximum lateral permeability. The same components favor to the formation of raised fracture-cavern capacity of the oil collector. There were also good conditions for interconnection of separate productive lenses when hydrodynamic unity of acumulation in the argillaceous deposits of the Bajenov suite was appeared. As a whole, several systems of the permeability connected with several systems of the secondary deformations and of the impregnation of hydrocarbon fluids are characteristic of the accumulations of the Bajenov deposits.

At present the resources of unconventional oil in the Bajenov suite are estimated in some dozens of billion tons, and the problem of their development passes in the “urgent” category.

The optimization of their development depends not only on the use of the newest technologies, but also on the further researches of irregularities of the distribution and localization of the largest oil accumulations in the Bajenov suite.

AAPG Search and Discovery Article #90135©2011 AAPG International Conference and Exhibition, Milan, Italy, 23-26 October 2011.