4th International Conference of Palaeogeography

153 / 2019-06-01 16:07:46

Sedimentary sequence，evolution model and petroleum geological significance of forced regression：A case study of the Miocene Zhujiang Formation of the Pearl River Mouth Basin in the Northern South Chin

forced regression; sedimentary sequence; evolution model; Zhujiang Formation; Miocene; Pearl River Mouth Basin

This study presents sedimentary sequence characteristics of falling stage systems tract of the Miocene Zhujiang Formation of the Pearl River Mouth Basin in the Northern South China Sea. The falling stage systems tract present offlap high-angle oblique foreset reflection structure in the seismic profiles which are parallel to the provenance and turbidite fan deposits with strong amplitude buninoid reflection structure are developed in the downdip direction of its front. The trajectory of migration of the shoreline shows a terraced downtrend in the direction of basin. The falling stage systems tract is characterized by the shelf-edge delta without topset beds. The bioturbation, horizontal burrow, muddy strip deformation, slide and slump features which are typical in slope areas can be observed in the cores of the falling stage systems tract. The falling stage systems tract was formed during the descent phase of relative sea level. Five sets of foreset beds controlled by high-frequency relative sea level eustatic cycles were developed, so ordinal regressive overlap can be observed for the five sets of shelf-edge deltas in the direction of sea. The favorable reservoir sandbodies located close to the upper boundary of the falling stage systems tract and the basal surface of forced regression. Those sandbodies favour the formation of lithologic oil-gas reservoirs by means of good trap sealing conditions, excellent oil-gas reserving performance and effective oil source communication of fracture system.