The north part of Tarim Basin

including Kuche depression

Shayar uplift and Awati-Manjiar depression

has an area of more than 100

000 sq km.On Sept.22

1984

more than 1

000m

3

oil and 2

000

000m

3

natural gas per day have been tested from well Shacan-2 on Yakela structure of Shayar uplift.Between Kuche and Awati-Manjiar depression

there is east-west extending Shayar uplift which is 460km long and 10-50km wide.It existed as a suc-cesional uplift during early Paleozoic to Mesozoic time.In the south of the uplift

Awati-Manjiar depression contains the Cambrian-Ordovician

Carboniferous-Permian and Triassic-Jurassic source rocks

among which the thick Cambrian-Ordo-vician and Triassic-Jurassic source rocks are widespread with better oil-generationpotential.North of the uplift

the Kuche depression contains mainly Triassic-Ju-rassic source rocks.The Shayar uplift

with many structural

stratigraphic

lithologic and combination traps

is in close proximity to those source rocks and in the direction of oil and gas migration.Therefore

it is favourable for searching gaint oil and gas fields.The oil and gas in well Shacan-2 are produced from the weathering zone of the Cambrian-Ordovician dolomites.The oil has high vanadium content(5.88 ppm)

high nickel content(0.76 ppm)and high V/Ni ratio(17.76).The GC analysis of the saturated hydrocarbon in the crude oil indicates thatthe oil has even carbon predominance of C

28

C

30

and C

32

and its CPI is 0.988.It is considered that hydrocarbons from the well Shacan-2 were probablyderived from the Cambrian-Ordovician marine source rock.However

the Triassic sporo-pollen fossils have been found in the crude oil and many Acri-tarch fossils have been examined in the Triassic sediments of the well Yoacan-1on Shayar uplift

therefore

marine intercalations might exist in Triassic

hydrocarbons from the well Shacan-2 were also probably derived from the Triassic-Jurassic source rock.From above

the authors consider that the Yakela pool is of multi-source origin.