Abstract: Oil and Gas in the Junggar Basin the People's Republic of China
The Junggar basin, located in the north of Xinjiang, China, and with an area of 130,000 km^2, is a compressional inland basin formed during the late Hercynian. Exploration and development of oil and gas in the basin has been run by Karamay Oil & Gas Corporation (KOC).
The basin has two basements, Precambrian crystalline basement and Early to Middle Hercynian fold basement. Maximum sedimentary cover from late Permian to Quaternary is above 20,000 m thick. There are six suites of source rocks developed in Carboniferous, Permian, Triassic, Jurassic, Cretaceous and Paleocene, respectively. Of the most important Permian and Jurassic source rocks, the former is oil-prone and the latter gas-prone. Total oil and gas resources in the basin are about 80-100×10^8t.
In the mid 1950's, Karamay oilfield, which is closely related to the overthrust belt, was discovered in the northwest margin of the basin. Since then, the proven oil reserves in the up to 250 km long overthrust belt with Karamay oilfield being the center can be compared to the Cordilleran Overthrust Belt in North America.
By the end of 1993, fifteen oil and gas fields have been discovered and the oil and gas reservoirs are found in all strata from Carboniferous to Tertiary except Cretaceous. The reservoir lithologies are mainly low mature sandstones, conglomerates as well as late Paleozoic volcanic rocks.The proven reserves are dominantly distributed in the northwest margin, which illustrated unbalanced exploration. The exploration degree in most part of the basin is still low.
Since 1961, the crude oil production has been increasing year after year. By 1997, the annual oil production is planned to reach 1000×10^4t. But the exploration and development of natural gas in the basin is still in the early stage.
In 1990's, since drilling spreads to the desert area in the central basin, oil and gas fields of large and middle scale, such as Cainan and Shixi, are soon discovered, and many oil and gas show and oil flow are also encountered in many structures, showing good exploration prospects. KOC is now shifting exploration emphasis on the central basin from east and west, and strengthens the exploration of Foredeep in the south margin, Wulungu Depression in the north and neighbouring small basins.
AAPG Search and Discovery Article #90956©1995 AAPG International Convention and Exposition Meeting, Nice, France