POOL-FORMING MECHANISM AND MIGRATION AND ACCUMULATION PATTERNS OF HYDROCARBON IN NORMAL PRESSURE HALFGRABEN-TYPED FAULT DEPRESSIONS

The Gaoy ou Depression in the North Jiangsu Basin is a Cenozoic halfgraben-typed fault depression.Its hydrocarbon pools are do minated by normal pressure,which have the characters of multi-stage evolution and the two stages of pool formation early in the Sanduo period of the Paleogene and late in the Yancheng period of the Neogene and develop reticulated,bedded and faulted three types of conduit systems and lateral,vertical and branchy three kinds of hydrocarbon migration and accumulation patterns.The hydrocarbon migration and accumulation is mainly later al in the K₂t—E₁f Formation of slope zones,branchy in the E₂d-E₂s Formation of deep depressed zones and vertical in faulted zones which including shallow (Ny),medium(K₂t—E₁f) and deep three sets of petroleum measures.