Well Aican-1 is located in the northwest part of Manas depression near the northwestern border of Junggar Basin

with its depth being 5700.13m.The well is ended in the Xiazijie Formation of the Lower Permian.Three suites of source rocks are intersected

i.e.the Lower Jurassic Sangonghe For-mation(J

1

2

s)

the lower Baijiantan Formation(T

3

1

b)of the Upper Triassicand the lower Wu'erhe Formation of the Upper Permian(P

2

1

w).Studies of the well temperature

vitrinite reflectance(Ro%)

TAI

T-max

S

1

/(S

1

+S

2

)

S

1

/TOC

CPI and 17 steranes and terpanes indices mea-sured by Rock-Eval indicate that the kerogen from the above mentioned for-mations is of humic type

derived in process of thermal evolution.On the basis of this

it is inferred that the threshold depth of oil-generation is about 2

830m

2

830-3

500m at low mature stage

3

500-4

400m at high mature stage

4

400-5

600m at wet gas and condensate stage

and deeper than 5

600m at over-mature stage.