Sand Body Types And Distribution Characteristics Of The Carboniferous Kalashayi Formation Of S75-AT10 Block In Tahe Area

Carboniferous Kalashayi Formation has been taken as the most potential layer of upper paleozoic of Tahe Oil field clastic area.In recent years,some exploration wells such as AT10,S1072,HY1 have obtained rich industrial oil and gas flows which achieves a breakthrough from the points(reservoirs)to the extensive regions in the upsalt Carboniferous Kalashayi Formation of Tahe Oil field.The sand body of the Carboniferous Kalashayi Formation is difficult to predict with the characteristics of deep burial,thin sand body and rapid lateral variation.Therefore,clearing the sand body types and the character of the distribution of roomage of the Carboniferous Kalashayi Formation is the key to oil and gas exploration and well deployment.Based on the previous establishment of precision sequence stratigraphic framework of Carboniferous Kalashayi Formation,through comprehensive analysis of well core,well logging,seismic and chemical analysis date,the types of sedimentary facies and its sedimentary systems have been defined.Then combined with the theory of seismic sedimentary and strata slice technology,research of the plane distribution of sedimentary facies and its space-time evolution of Carboniferous Kalashayi Formation has been conducted.Finally,according to the important wells' cores,well logging and seismic data,the sand body types have been described in detail,through the analysis of the characteristics of the lithology,physical properties and longitudinal cycle of different sedimentary microfacies,the sand body distribution in different system tracts and distribution characteristics of favorable reservoir sand body have been cleared.The research shows that Carboniferous Kalashayi Formation in study area is a delta-tidal interaction deposition.The sand bodies are mainly distributary channel,underwater distributary channel,mouth bar,tidal sand and tidal reformed distributary channel.Distributary channel sand bodies develops in all third-order sequences HST(highstand system track),SQ1 period mainly in the north and southwest regions,SQ2 and SQ3 period only in the north.Underwater distributary channel sand bodies develops in each third-order sequences HST and TST(transgression system track),SQ1 HST to SQ2 TST period in the northern region and the southwest region,SQ2 HST to SQ3 HST period in the north-central region of advanced delta front.Tidal reformed distributary channel develops in SQ2 TST,mainly in rivers and tidal mixing interaction zones.