Abstract:

Songliao basin has experienced Yanshan movement and Himalayan movement.Yanshan movement resulted in strong folding,and the large structures and oil/gas reservoirs in Daqing placanticline in northern Songliao basin have mainly been formed during this period.Himalayan movement,though being weak in Songliao basin,has adjusted and modified the early formed oil and gas pools and become a number of secondary oil and gas pools in the northern part of the basin.Homogenization temperature measurement of organic inclusion in minerals shows that there have been two periods of hydrocarbon expulsion from source rocks in the first member of Qingshankou Formation,and three periods of hydrocarbon infilling into Fuyu and Yangdachengzi reservoirs.According to authigenic illite K/Ar dating,secondary oil/gas reservoirs have been accumulated in 51-35 Ma in the above mentioned two reservoirs in the surrounding area of Qijia-Gulong and Sanzhao sags on both sides of Daqing placanticline.This indicates that during the Himalayan movement,the early formed oil and gas reservoirs in northern Songliao basin have sustained a certain alteration and then reaccumulated and become secondary oil and gas reservoirs.

Key words: Songliao basin, tectonic movement, reservoiring time, fluid inclusion, hydrocarbon accumulation