Sedimentary Sequence and Lithologic-stratigraphic Trap of the Middle Segment of Hanjiang Formation in the Shelf Break Zone in Southeast Panyu Natural Gas Area, Pearl River Mouth Basin

Key words: 
• Pearl River Mouth Basin /
• Panyu natural gas area /
• shelf break zone /
• the middle segment of Hanjiang formation /
• sedimentary sequence /
• lithologic-stratigraphic trap

Abstract: On the  basis of previous studies on the sequence stratigraphic framework of Zhujiang—HanJiang Formtation in the shelf break zone in southeast Panyu natural gas area, Pearl River Mouth Basin, and comprehensively using well drilling, logging and seismic data and sequence stratigraphic principles, the characteristics of sedimentary sequence  for SQhj₂ of the middle segment of Hanjiang Formation was studied.It was divided into lowstand system tract, transgressive system tract and highstand system tract, and the lowstand system tract can be recognized as two stages（two fourth order cycles）—the early and late stage lowstand system tract. The sequence structure and depositional system tract has the feature of four-layer architecture. From up to down, the SQhj₂ can be divided into transgressive system tract ,highstand system tract, the early and late stage lowstand system tract in the seismic section. On the basis of the constitutive characteristics of the sequence structure and depositional system tract was demonstrated, SQhj₂ sedimentary sequence model was established. In this model, under the sequence boundary of SB13.8, the late highstand system tract of SQhj₁ developed the falling stage system tract. And above the SB13.8,the sequence of SQhj₂ developed the early and late stage lowstand system tract under the shelf break. The favorable zones of the study area were predicted, and the sand body of lowstand system tract controlled by the paleo uplift and the shelf break is the favorable reservoir sand body and the distribution area of the lithologic and stratigraphic trap.