--> ABSTRACT: The Role of Karst in the Formation of Yurubchen-Tokhomsk Field, Siberian Craton, Russia, by V. G. Kuznetsov; #91021 (2010)

Datapages, Inc.Print this page

The Role of Karst in the Formation of Yurubchen-Tokhomsk Field, Siberian Craton, Russia

KUZNETSOV, VITALY G.

Yurubchen-Tokhomsk field is the largest hydrocarbon deposit of the Siberian craton. Main productivity is connected with Riphean carbonate rocks, including dolomites with stromatolite, bacterial and polycrystalline textures. Matrix porosity (intercrystalline) is usually less than 1%. The average value of secondary porosity is 8-9% where the type of pore space is fractured-cavernous. High productivity from individual wells and drilling mud loss are evidence of local zones of enhanced cavern and fracture porosity. Seal of the Riphean pool is Vendian shale and, importantly, Vendian-Cambrian salt.

Paleogeographic and paleomorphologic reconstructions, petrographic and geochemical study of rocks and well log analysis were used for investigation of the reservoir and trap. Following Prevendian continental breakup, the Riphean surface formed a carbonate plateau with a height of approximately 80-90m. This surface was limited to the north by Archean granite and gently dipped to the south and east. Meteoric water then infiltrated through this carbonate massif, karsted it and formed significant cavernous porosity. Karst processes were intensified in zones of tectonic fractures. Secondary cementation took place in unloaded zones in lower parts of the relief, owing to retrograde precipitation of calcium and magnesium carbonates. In these areas, impermeable rocks were developed. A connection between well productivity and position with respect to the paleorelief is established. The Riphean trap is formed by Prevendian relief, tectonic structure, a fault zone and granite massif to the north and lithologic replacement to the south and east.

AAPG Search and Discovery Article #91021©1997 AAPG Annual Convention, Dallas, Texas.