Study On Micro-facies Within High-resolution Sequence Framework Of Fuyu F3 Layer In Daqing Placanticline,Songliao Basin

This paper studied on Fuyu oil layer(F3 layer),which as the main target of deep exploration,F3 layer is dominated by fluvial facies.Fluvial sequece division has been the difficulty and hot spot of the sequence stratigraphy.This paper use high-resolution sequence theory,and its stratigraphic classification and correlation based on multi-stage base-level cycles as a reference surface,based on fluvial sedimentology,combine with stratigraphic stacking patterns analysis that reflects the change of base level cycle(A/S),carry out the division and correlation of fluvial resolution sequence stratigraphy in F3 layers.Comprehensive utilization of core data,drilling/logging and seismic data,on the basis of observaton and description of cores,determined the sedimentary facies and sedimentary Microfacies type and identification,established rock-electrical explainate template,suggest that there is High-sinuosity meandering river in study area,and identified three microfacies in study area,they are meandering channel、crevasse splay/crevasse channel complex、floodplain;according to the difference of lithofacies characteristics and well log shape of the meandering channel,meandering channel can be further divided into two typical style,the superposition meandering channel and the normal meandering channel;according to the different develop levels of paleosols,paleosols that develop on the flood plain can be divided into high-maturity paleosols,medium-maturity paleosols and low-maturity paleosols.By analysis of stratigraphic stacking patterns and identification of depositional cycles,F3 layer can be divided into two fourth-order sequence units,F3.1 and F3.2.and each can be sub-divided into five times of channel through the characteristic of channel、crevasse splay、paleosol in base level cycle.then,use the fluvial sequence correlation of Timthy.A.Cross professor,so as to establish fine stratigraphic framework of channel sand in F3 layer.In the sequence stratigraphic framework,analyze the characteristics of the sedimentary Microfacies profile and planar distribution of F3 layers,suggest that F3 layer mainly develops high sinuosity meandering river,with bend cut and abandoned frequently,Thick lateral migrated channel sandstone superposed,and develop crevasse splay/crevasse channel complex.On this basis,determine the sedimentary evolution of F3 layers:the thick river is generally close to the cycle interface F3.1 and F3.2.overbank deposit developed internal cyclel.Analysis of F3 layers reservoir properties,suggest that the F3 layers is the reservoir with low porosity and low permeability,the reservoir is mainly meandering channel and crevasse channel.On the basis of understanding of main controlling factors of oil and gas accumulation and their distribution,favorable exploration area can be divided into three categories,and the more favorable exploration area are Gaotaizi/Putaohua/west Gao/Monocline of west Xinggao.