THE CHARACTERISTICS AND DIAGENESIS OF PERMIAN REEF ROCKS IN NANPANJIANG AREA AND THEIR RELATIONSHIP TO OIL/GAS POOLS

Based on the geographic location,exposed configuration and the com-plex of the reef body,the reef rocks in Nanpanjiang Area can be divided into three types as platform marginal linear reef,platform marginal horse-shoe reef and patch reef.The principal types of the reef rocks are of framestone,bindstone;reef breccia,etc.The reef-building organisms can be divided into framework-building,binding,binding and attaching organisms on the basis of the different effective to the reef formation.Permian reefs are characterized by reef building up at the time of trans-gression,and dying out at the time of regression,as well as the conti-nuously shifting of a number of reefs.The reefs in this area distribute at the margin and interior of basin facies.As the source rocks were under favourable conditions of hydrocar-bon expelling stage,and valid pore formed at right time by solution,these reefs can be formed as reefoid oil/gas pools(in term of short distant oil trapping).However,since the liquid hydrocarbon restored in such reefs has experienced an over-maturation stage and has been pyrolyzed to be gase-ous hydrocarbon and solid bitumen,the subtle reefoid gas pools can be discovered by the valid exploration activities in the area.