Analysis Of Reservoir Characteristics And Main Control Factors Of Jurassic Toutunhe Formation Reservoirs In Fubei Region Of The Eastern Junggar Basin

Based on the previous studies and achievements,this paper utilizes a series of analytical methods,such as ordinary thin slices of rock,castings sheet,SEM,physical properties,logging and earthquakes.Through the analysis of the sedimentary facies,reservoir petrology,pore type,physical properties and diagenesis of the Toutunhe formation reservoirs in Fubei region,we can reach the following conclusion:(1)The depositional system in study area belong to the braided river delta sediments,reservoir bodies are mainly composed of delta front sub-aqueous channel,the estuary dam and delta plain distributary channel.The most important type of clastic sandstones is feldspathic litharenite,secondly litharenite.The main reservoir space is residual intergranular pores and induced porosity is few.Porosity and permeability of sandstones have good correlation.Reservoir rock type overall characterized medium porosity,medium to low permeability.(2)The main diagenesis of Toutunhe formation is mechanical compaction,cementation,dissolution and precipitation of authigenic clay minerals.Based on the analysis of the vitrinite coal emission rate,the degree of compaction andof the contact relation of clastic particles,the pore type and the development degree of authigenic minerals and their types,suggest that the reservoirs are mainly in the early diagenetic stage B and middle diagenetic stage A.(3)The sandstones reservoir of Toutunhe formation in the fubei region is divided into 3 diagenetic facies types,which are weak compaction diagenetic facies,weak compaction-chlorite cementation diagenetic facies,medium compaction diagenetic facies.The diagenetic facies of favorable reservoir development are weak compaction-chlorite cementation,the diagenetic facies of favorable reservoir development are weak compaction-chlorite cementation.(4)Sedimentary microfacies are the primary factors controlling reservoir development,in which the distributary channel and the sub-aqueous distributary channel sand body are the most favorable type of sand reservoir,and they also controll the types of clastic components.In the later period of burial diagenesis,the clay mineral thin films(especially authigenic chlorite)preserved a large number of primary intergranular pores in the Toutunhe formation,which is favorable for reservoir development.Therefore,sedimentary microfacies and clay mineral thin films are the main controlling factors of reservoir development in Toutunhe formation.