Shuanghe oilfield in Biyang depression is one of the large structural-lithologic composite oil reservoirs in eastern China. Cumulative proved oil reserves in place have reached 101.76 million tons by the end of 2001 since overall exploration and development began in 1977. This oilfield has rich source rocks

well-developed sandbodies

good migration pathways

favorable matching of trap formation and sandbodies

and superior preservation conditions

all of which are favorable for hydrocarbon accumulation. Along with the formation and evolution of Shuanghe nose structure

sandbodies in the 3

rd

member of Hetaoyuan Formation in southern Biyang depression change gradually from downdipping pinch-out to upwarping pinch-out

leading to the formation of the small but prolific Shuanghe oilfield with large reservoir space and enough time for charging hydrocarbon.