--> ABSTRACT: Neocomian Sequence Stratigraphy, Yarsomov Trough, West Siberian Basin, Russia, by Vladimir N. Vyssotski, Steve F. Barret, and Gerald R. Baum; #91019 (1996)

Datapages, Inc.Print this page

Neocomian Sequence Stratigraphy, Yarsomov Trough, West Siberian Basin, Russia

Vladimir N. Vyssotski, Steve F. Barret, and Gerald R. Baum

The Neocomian was a major regressive event in the Yarsomov Trough that prograded from east to west and downlapped onto the Bazhenov Shale, the major source rock interval. This general Neocomian regression was punctuated and disrupted by a series of type 1 unconformities and the concomitant deposition of lowstand depositional systems. These systems consist of a series of detached fans, unconfined lowstand wedges, and confined incised-valleys. These sand-prone lowstand depositional systems are the primary reservoirs and provided the conduits for the migration of hydrocarbons. Ineffective seals at the upper contacts of the detached fans and lowstand wedges limited trapping of hydrocarbons in the more distal depositional systems.

Depositional rates were high, and sediments were dispersed by a variety of mass-movement processes, causing rapid deposition on the subaqueous basin slope and floor. The fans are grouped into two major process types: gravity and slump. The best reservoirs are lenticular, non-channelized basin floor fans deposited as high density sediment gravity flows. Fans deposited by slump processes are characterized lenticular sands with limited reservoir continuity. Both fan types and potential seals can be predicted ahead-of-the-drill by applying seismic and depositional sequence analysis technologies, thus significantly reducing exploration risk.

AAPG Search and Discover Article #91019©1996 AAPG Convention and Exhibition 19-22 May 1996, San Diego, California