Provenance Of Middle And Deep Layers Of Baiyun Sag And Its Influence On Reservoir Quality

The Zhuhai Formation in Baiyun Sag,Pearl River Mouth Basin is generally deep,with high geothermal background and complex reservoir influencing factors.In this paper,based on provenance evolution,sedimentary facies,petrology and mineralogy,diagenesis and pore characteristics,the provenance system of Zhuhai Formation in Baiyun Sag and its impact on reservoir quality characteristics were evaluated,and the distribution of favorable reservoirs was predicted by comprehensive zoning characteristics.The results show that during the sedimentary period of Zhuhai Formation,there are two source systems inside and outside the basin in Baiyun Sag.The supply of source systems inside the basin is relatively limited,and the supply of source systems outside the basin is mainly.From the early to late deposition,the provenance supply in Baiyun Sag gradually evolved from the surrounding Mesozoic paleouplift to the South China fold belt.Delta sedimentary system is developed in Zhuhai Formation of the study area.Near provenance is mainly delta plain subfacies,while far provenance is mainly delta front subfacies.The medium-coarse grain facies belt in the near provenance area mainly develops(subaqueous)distributary channel and mouth bar thick sandstone.Combined with other reservoir characteristics,comprehensive comparative analysis shows that the near provenance sedimentary area is a favorable reservoir development area,and the sixth member of Zhuhai Formation-the fifth member of Zhuhai Formation is the characteristics of the dominant development layer.The deep reservoir type in the depression belongs to low porosity-low permeability type.The reservoir space types mainly include primary pores,secondary pores and fractures,and secondary pores are the main types.Through quantitative characterization of diagenesis,it is considered that medium-coarse grained sandstone is more conducive to the preservation of primary pores,and it has the characteristics of weak cementation and conducive to dissolution and pore enlargement.Combined with the prediction method of "medium-coarse grain+sedimentary microfacies" and fracture distribution characteristics,the "sweet spot"development area of reservoir is obtained by superposition:PY33 well,PY35 well nearby area,LH32 well nearby area,BY5 well nearby area.