Reservoir Fine Description Of Chang 4+5 Reservoir Of Yougou Area In Wuqi Oilfield

Yougou area in Wuqi Oilfield begin to develop in 2003,and the type of the Chang 4+5 reservoir is low permeability and low pressure sandstone,which exists the insufficient of reservoir natural energy,production wells with low production capacity,decreasing quickly,stable production difficult and other shortcomings.The wells had been waterflooded since 2008.After water injection,the formation pressure recovery effect was better,but some oil wells appeared to reduce production capacity,increase water content and other issues.In order to further improve the recovery ratio,the method of a detailed reservoir description technology was adopted in this paper.According to the core,logging,mercury and other data,the Chang 4+5 reservoirs were subdivided into Chang 4+51,Chang 4+521 and Chang 4+522 reservoirs with the petrology and geological methods.The results shows that,the study block develops with nasal uplift,and the whole study area is gentle.Yougou area Chang 4+5 reservoir belongs to the delta front subfacies,including three sedimentary microfacies,underwater diversion channel,diversion bay and river wing.The underwater diversion channel is the main reservoir sandbody,and the physical parameters are better.The lithology of the study area Chang 4+5 reservoir has the highest proportion of medium-fine feldspar sandstone,the type of cementation is mainly film-pore,sorting characteristics to the highest proportion of good,degree of roundness to the highest proportion of sub-edge,pore throat combination with small hole and medium-throat accounted for the highest proportion.The average porosity is 10.43%,the average value of permeability is 0.58×10-3 ?m2,the oil saturation is 15.87%,and the pore throat mean distribution is in the range of 20-80 ?m.Based on the results of the study,the Chang 4+5 reservoir in the Yougou area of Wuqi Oilfield is a special low permeability-ultra low permeability reservoir.Although this type of reservoir has a certain storage capacity,the permeability value is low.In order to further improve the recovery rate,water injection or gas injection development measures shall be early taken.