Sedimentary Microfacies And Sand Controlling Mechanism In The Third Member Of Funing Formation In Gaoyou Sag

Sedimentary microfacies are one of the principal factors in controlling deep reservoir physical property of internal slope in Gaoyou Sag,Subei Basin.Elaborate research on sedimentary microfacies,analyzes about mechanism of sand dominate along with study of influence factors on reservoir may help understand the sedimentary microfacies of slope area and improve the drilling succeaa rate.Stratigraphic correlation and research on sedimentary microfacies are based on well logging,cutting logging,core,analysis experiment and regional geology and seismic data.The 3rd member of Funing Formation could be divided into 10 sands group.Research also makes clear that Fu3 Member of research area is part of the Fu3 enormous delta in Subei Basin,consists of sedimentary microfacies such as underwater distributary channel and mouth bar deposited in two depositional setting:slope zone and fault zone.Mechanism of sand dominate based on horizontal distribution and vertical evolution of each sands group shows distant provenance,broad and gentle basin as well as transform of lake waves control the large-scale fine delta.The construction of Wu2 Fault control the enrichment and extend of sand bodies in downthrown side.Slope break belt in delta front is the essential condition in forming turbidity sand body.Diagenesis analysis shows good correlation between sedimentary microfacies and reservoir physical property,and sedimentary microfacies control the deposition,scale and distribution of sand body.Diagenesis control the pore type and physical properties of sandstone.Cementation and compaction during late diagenetic stage directly result in the low porosity and low permeability.Reservoir classification prediction is finished by summarizing the laws about horizontal distribution and the laws about vertical evolution of each sands group.The reservoir is classified into four classes,class I is good reservoir,class II and class III are relatively good reservoirs and class IV is relatively poor reservoir.