Print this pageStructure, Evolution and Oil and Gas Potential of the South Turgay Basin, Kazakhstan
PARAGULGOV, DR. KHALIT KH., DR. TIMUR KH. PARAGULGOV, MICHAEL J. SWITEK, and HOWARD R. LOWE
The South Turgay Basin is part of the larger Turgay Depression located in Central Kazakhstan. The Basin originated as a continental rift during the Jurassic. The stratigraphic section of the Basin is divided into (1) the Proterozoic metamorphics, (2) pre-rift Devonian to Carboniferous volcanic and sedimentary rocks, (3) terrigenous Jurassic sediments, mainly lacustrine but partly alluvial, associated with the rifting and (4) post-rift continental and marine Cretaceous to Cenozoic deposits. Structurally, the Basin is divided into three tectonic elements: the Zhylanshik Trough (300 x 200 km) to the north, the Aryskum Trough (300 x 175 km) to the south, and the Mynbulak arch which separates the two. Displacement along normal boundary faults is as much as 4 km.
All hydrocarbon accumulations found to date are in the Aryskum Trough, mainly within the Jurassic and Neocomian section, where high quality source rocks, reservoirs and traps are in dose proximity (10 to 25 km). TOC reaches 15% in the combustible Jurassic shales. The thermal history of the Jurassic rocks is optimal for hydrocarbon generation. Reservoir porosity reaches 30% with maximum permeabilities of up to 2.5 darcies. The largest traps are drape folds over horsts. Hydrocarbons also occur in the pre- and post-rift formations and weathered basement. The Basin contains 51 thousand cubic kilometers of sediments which are calculated to have generated 2737 million tons of oil (820 million tons recoverable). Drilling has confirmed 200 million recoverable tons, the main fields being Kymkol, Aryskum, Konis, Kyzilka and Akshabulak.