Xujiaweizi fault depression has experienced three relatively large volcanic activities during rift fauting

among which the volcanic activity duing the deposition of Yingcheng Fm had the longest duration.The volcanic activity speeded up the maturation of the major source rocks including deep Huoshiling Fm

Shahezi Fm and Yingcheng Fm. Simulations of burial history

thermal history and hydrocarbon generation history show that the R

o

value of Huoshiling Fm source rocks at a burial depth of 1300m would have rapidly reached 0.7% in about 1Ma.The R

o

value of Shahezi and Huoshiling Fins source rocks would have reached 1% at a burial depth of 2600m.Before the deposition of Quantou Fm

Shahezi and Huoshiling Fins source rocks would have entered the peak of gas generation.Before the deposition of Qingshankou Fro

Yingcheng Fin source rocks would have been in the peak of gas generation

while Shahezi and Huoshiling Fms source rocks would have begun to generate dry gas.At this time

the regional seals of the 2

nd

member of Denglouku Fm and the 1

st

and 2

nd

members of Quantou Fm would have been formed

leading to the formation of gas pools in Yingcheng-Quantou Fms.By the end of the deposition of Nenjiang Fm

the movement of boundary faults led to the redistribution of gas pools in Yingcheng-Quantou Fms.