Depositional Systems And Hydrocarbon Significance Of Deep-water Channel Systems In The Southern Qiongdongnan Basin

Deep-water channel systems(DCSs) is one kind of the deep water sedimentation of the passive continental margin. it is the main conduits to transport terrigenous clastic sediments into deep sea.it takes an important position in the deep sea sediments. and at the same time DCSs is the major reservoirs for the deep water exploration.Based on the theories such as seismic stratigraphy, sequence stratigraphy, petroleum geology, et,al. multiple stages DCSs since Miocene have been discerned in the southern slope of Qiongdongnan basin.by using seismic data and log parameter nearby. The sedimentary characteristic and distribution of deep-water channels, lobes and sheet sands in the DCSs have been indentified and analysed in the study area.The DCSs has comflex geomorphology and distribution which were controlled by the sea level fluctuations and the slope evolution. The development of DCSs are corresponds to relate sea level change and slope evolution in the northern South China Sea margin, The scale of sea level fluctuations occur in Miocene and Pliocene(21Ma,16.5Ma,l5.5Ma,12.5Ma,10.5Ma,8.2Ma,5.5Ma). and the slope evolution is also an important effect of the DCSs.In the early Miocene,there are no complete shelf-slope-basin system. The deep channel system settled in the slope basin.Since the middle Miocene, the shelf-slope-basin system was well developed.The clastic sediments were transported into basin floor via the filled slope basin.With drop of the large scale of the sea level,DCSs sediments deposit mainly in the basin floor.on the other hand,with drop of small fluctuation of sea level,the DCSs deposits in the slope basin.Through analyse of the hydrocarbon source rocks,the trap condition,and the migration path and accumulation condition in the study area.Miocene DCSs sand bodies are well loghological trap and the strata-structure combination trap,and has the good hydracarbon prospect.