PETROLEUM SYSTEMS IN THE HONGZE SAG, THE NORTH JIANGSU BASIN

The Hongze Sag is a middle-small rift located in the west end of North Jiangsu Basin.It can be divided into 4 petroleum systems as the Shunhe,Guanzhen,Suxiang and Jia'nan,among which the Shunhe and Guanzhen petroleum systems are favorable but distinguished.Further more,the petroleum systems of Shunhe and Guanzhen can be divided respectively into 2 accumulation systems as the northern and the southern ones.Within the accumulation system,migration takes place almost the same time as trap formation.The Sanduo Movement is the key period to control petroleum accumulation and distribution while tectonic subsidence and geothermal history are the key factors to affect abundance.Insufficient reservoirs are formed due to the later time and lower maturation of organic matters.The best plays for oil accumulation are the deep-fault belts in the Southern Guanzhen and Southern Shunhe accumulation systems,and the deep monocline belts in the Northern Guanzhen and Northern Shunhe accumulation systems.Other belts in the Northern Guanzhen and Northern Shunhe accumulation systems can also be favorable,especially the belts near source rocks.