The main body of Jurassic source rock in Kuqa foreland basin is in its peak of oil generation

with R

o

value in the range of 0.55%-1.88% and average value of 0.93%.While that of Triassic source rock is in its late period of oil generation

with R

o

value in the range of 0.60%-2.59% and average value of 1.1%.The(available)borehole temperature measurements indicate that the temperatures at 2 000

4 000 and 6 000 m in Kuqa foreland basin vary in the range of 40-60℃

60-90℃

and 100-150℃

respectively.Thermal history restoration shows that Kuqa foreland basin has always been in relatively low heat flow conditions since Triassic. The surface heat flow was relatively high in Mesozoic(50-55 mW/m

2

)and has been continuously and slowly lowering since Cenozoic and finally to the contemporary 40-50 mW/m

2

.The Triassic and Jurassic source rocks entered into low maturity stage in 160-170 Ma and 100 Ma respectively

and entered into gas generation stage in 145 Ma and 75 Ma respectively.The earliest area that entered into low maturity stage is Kelasu

followed by Qiulitage structural zone

and Baicheng sag was the last one.The maturity of organic matter began to increase remarkably since 23 Ma

and both the Triassic and Jurassic source rocks are in their gas generation stage now.The maturity of source rock is mainly controlled by sedimentary and burial history and thermal history of the basin.Overthrusting and gypsiferous rock have also certain influences on maturity of source rock

the intensity of which depends on the displacement of overthrust fault and the thickness and lateral variation of gypsiferous rock.