CHANGE IN CHEMICAL AND ISOTOPIC COMPOSITION OF NATURAL GASES IN LOCAL STRUCTURES OF THE SULTANDANDZHAR SWELL

Abstract

We chose for investigaton the Koshabulak tectonic structure, within the Sultan-Sandzhar swell, which is one of the group of Pitnyak tectonic uplifts of the Bukhara Bench, which were formed during Hercynian time and continue to manifest active seismicity. The complexity of the tectonic structure and mobility of the Koshabulak structure and of the Sultan Sandzhar ridge, as well as the absence of recoverable accumulations of hydrocarbons within them, apparently result from a quasi-stable relationship between the input of gases into the reservoir rock of the structure from gas-collecting regions and their escape into the atmosphere. The hydrocarbon gases of the Koshabulak tectonic structure are more than 99 percent methane. The scale of escape of methane from the Koshabulak tectonic structure during Neogene-Quaternary time clearly cannot have been compensated by metamorphism of organic matter in the sedimentary rocks within the structure, even if the oil-generating potential was realized exclusively by the generation of methane.