Research On The Reservoir And Pool Characteristics Of Chang4+5 And Yan9 Oil-bearing In Baimayaoxian Of Dingbian Area

Baimayaoxian area is an important research block of Dingbian oil field,and Chang4+5 and Yan9 reservoirs are main producing formations in this area.Presently,the oil field has entered into the development stage,however the previous geological studies were not clear enough,and the distribution of reservoirs in different formations is incompletely understood,which will influence the later work process,including the next macroscopic plan for the layer series of development,the adjustment of injection well pattern and the correspondence among water injection layers.So it is necessary to study further and deeply of this region again.Therefore,the system research of Chang4+5 and Yan9 reservoirs and pool characteristics has great practical significance for the further scientific and effective exploration and development in this area.This article is directed by the theories and methods relating to reservoir geology and petroleum geology,using the core data,logging,formation testing and analysis test date,on the basis of the thin layer division,to study the sedimentary facies,reservoir and pool characteristics of Chang4+5 and Yan9 oil-bearing formations in Baimayaoxian area.Chang4+5 reservoir belongs to delta front sub-fades in the study area,and the dominant sedimentary microfacy is underwater distributary channel;Yan9 reservoir belongs to delta plain sub-fades in the study area,and the dominant sedimentary microfacy is distributary channel.The rock type of Chang4+5 reservoir is fine feldspar sandstone in the study area.The main cementing materials include ferruginous calcite and illite.And the main pore type of the reservoir is feldspar dissolved pore,the pore throat is mainly fine pore and micro-fine throat,which mainly belongs to extra-low porosity and permeability reservoir.Chang4+5 reservoir has serious aeolotropism,and reservoir sensitivity is weak,Chang4+5 reservoir is dominated by the type ?a(poor)reservoir in the study area.The rock type of Yang reservoir is middle lithic quartz sandstone in the study area.The main cementing materials include kaolinite and calcite.And the main pore type of the reservoir is original intergranular pore,the pore throat is mainly middle pore and coarse throat,which mainly belongs to low pore and permeability reservoir.Yan9 reservoir has weak aeolotropism,and reservoir sensitivity is also weak.Yan9 reservoir is dominated by the type I(good)reservoir in the study area.The Chang4+5 reservoir lithologic lower limit is fine sandstone,and the oil bearing condition lower limit is oil spot.The effective reservoir selective of the lower limit of porosity is 7%and permeability is 0.17mD,and the electrical lower limit are RILD?15?·m,?t?215?s/m,So?20%respectively.The Yan9 reservoir lithologic lower limit is medium sandstone,and the oil bearing condition lower limit is oil spot.The effective reservoir selective of the lower limit of porosity is 9.6%and permeability is 6.0mD,and the electrical lower limit are RILD?8?·m,?t?242?s/m,So>21%respectively.Chang4+5 is considered to be lithologic reservoir,the hydrocarbon mainly accumulated in Chang4+52-1 layer,and mainly distributed in the northeast of research area,where mainly are delta front underwater distributary channel sand and structural high points;Yet,Yan9 is considered to be structural-lithologic reservoir,the hydrocarbon mainly accumulated in Yan91-2 layer,and mainly distributed in the south of research area,where mainly are delta plain major distributary channel and structural high points.The distribution of Chang4+5 and Yan9 reservoirs are controlled by "favorable facies and structural nose-shaped uplifts",and the influence of structure to Yan9 reservoirs is more obvious.According to the reserves estimation and evaluation,Chang4+5 and Yan9 reservoirs belong to light and conventional oil reservoirs,which are characterized by middle-shallow layer,low-production,low abundance and small reservoir scale.