Discovery of Tengiz, Karachaganak, Zhanazhol, and other giant fields in the last two decades has lifted Kazakstan into one of the large oil-gas regions of the world. Prospective sedimentary basins have an area of 1.7 million sq km of the total 2.7 million sq km of the republic.
For purposes of oil and gas the country is divided into Eastern and Western Kazakstan at the Mugodzhar anticlinorium. More than 20 favorable sedimentary basins are recognized within these regions. Part of them (North Caspian, Ustyurt-Buzachi, Mangistau) include the main oil-gas producing areas of the country and are in the west, whereas the majority (Aral, North Kazakstan, North and South Torgay, Teniz, Karagandin, Shu-Sarusuy, Syrdar'ya, East and West Iliy, Balkhash, Alakol, Zaysan, and Pri-Irtysh) are in Eastern Kazakstan. Some 90 percent of Kazak oil production is in the western part, whereas the main industry is in the east. Therefore, discovery of even small fields in the east would contribute significantly to industrial development.
Most of the basins of Eastern Kazakstan occur along the margins of the Central Kazakstan massif, and only three (Shu-Sarysuy, Teniz, and Karagandin) are in its interior. They form a mosaic of micro continents ("middle massifs") of various age. Ophiolites are present on the borders of these micro continents; up to 15 such ophiolite zones (sutures) are recognized in Kazakstan.
Orogenic stages recorded in Eastern Kazakstan are the Takon (end of Ordovician), Tel'bes (Middle Devonian), Saur (between Early and Middle Carboniferous), and Sayak (Early Permian). In a relatively short time preceding Tel'bes folding an enormous pile of silicic volcanics was deposited and several rift zones formed. Rifting attenuated in Famennian time accompanied by marine transgression and carbonate deposition. Salt and sulfate-salt deposits collected under lagoonal conditions in short time intervals. Redbeds and variegated sediments were deposited late in the Paleozoic.
Exploration of most of the basins of Eastern Kazakstan has not been extensive. It was oriented largely on Mesozoic and Cenozoic targets, which are productive in adjacent regions. Commercial discoveries have been made only in North and South Torgay and Shu-Sarysuy basins. Up until recently the Upper Paleozoic clastic-carbonate rocks of these basins were regarded by many as basement. Studies in the last two decades, however, have demonstrated that the Upper Paleozoics of most of the basins have a quasi-platformal nature and are 2-6 km thick.
The basins of Eastern Kazakstan are assessed as having a very high potential for oil and gas. With a present annual rate of production of 25 million tons of oil and 12 billion cu m of gas, the level should increase to 75-125 million tons and 16-18 billion cu m by the year 2002. Potential hydrocarbon resources of the basins of Eastern Kazakstan are assessed at 4-7 billion tons oil equivalent (28-49 BBOE). (Taken from Paragul'gov and Paragul'gov, 2000; digested in Petroleum Geology, vol. 35, no. 2, p. 130-136, 2001, two maps, in preparation.)
Copyright 2001 James Clarke. You are encouraged to print out this News
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