Sequence stratigraphic framework and favorable zone prediction in Guantao Formation of Raoyang sag,Bohai Bay Basin

Based on the theory of high resolution sequence stratigraphy and sedimentology,the sequence stratigraphy and sedimentary facies of Guantao Formation in Raoyang sag were studied by comprehensive analysis of core data,drilling data, logging and seismic data. The distribution of reservoir,reservoir-cap combination and distribution of hydrocarbon were further analyzed. The study shows that Guantao Formation is one long-term base-level cycle,which can be divided into three intermediate-term base-level cycles and seven short-term cycles. The braided river deposits are in the two short-term cycles at the bottom of Guantao Formation and other layers are meandering fluvial deposits. Controlled by sedimentary provenance,palaeogeomorphology and fracture systems,the river channel deposits are characterized by a NNE ribbon pattern distribution,wide belt exhibition near the provenance and narrow belt exhibition far away from the provenance. Guantao Formation can be divided into three sets of reservoir-cap combination( Ng3-( 3 + 2)/ Ng3-1,Ng2-2/ Ng2-1,Ng1/ Nm). Because of the favorable reservoir-cap combination and structural condition,Liulu structural zone is the favorable zone of Guantao Formation in Raoyang sag.