Abstract:

The Miocene is represented by clastics and argillaceous rocks intercalated with evaporites totalling 1,000—6,050m thick and is divided from bottom to top into Keziloi Fm,Anquan Fm and Pakabulake Fm.Lacustrine sediments of the Miocene are quite well developed.Among the others,the marine transgressive lacustrine facies of the bathyal Anquan Fm is the most developed,while the deltaic,fluvial and alluvial-fan facies,as well as the turbiditic facies of the Pakabulake Fm are also developed.The Anquan Fm formed in hemi-deep lacustrine area is the main source rock in upper Tertiary.Source rocks confined to thickness no less than 150m has an area about 17,000km²,while its total volume is up to 10,000km³.The lower part of the Pakabulake Fm is the most important target formation,in which commercial oil and gas of Kekeya oilfield have been found.Therefore,the Miocene rocks exhibit good conditions for looking both for Petroleum generated and accumulated in situ,and for petroleum generated within older source rocks but accumulated in newer reservoirs.Preliminary study demonstrates that the Kashi and the Yecheng areas can be considered as the first grade of target areas,the Maigaiti slope and thewestern uplift zone of Shache County are of second grade and the area south of the Mazatake line is of the third grade,while the Kezikealte fracture zone might be favourable in searching for oil and gas related to overthrusting.