The Reservoir Comprehensive Evaluation Of Fuyu Oil Layer In Aobaota And Putaohua Oil Field

The structure of Aobaota and Putaohua oilfield is tretyi structure - Putaohua and Aobaota structure which is situated in the south of Daqing placanticline of center concave in Songliao basin,and with Taipingtun anticline structure in the north,Aonan nosing structure in the south,Sanzhao concave in the east,Gulong concave in the west,which is in the areas of 840 square kilometers.The western of Daing placanticline is precipitous,and its east is smooth.The dip of the rock stratum is more and more big from top to bottom.The thickness of the rock stratum gets thinner from two wings to crown and its lithologic character is more and more coarse.The target of this research is Fuyu Oil Layer,which is a part of the Third and Fourth Member of the Quantou formation of Lower Crataceous.The lithologies in this area mainly consist of siltstone,fine sandy siltstone,silty fine sandstone and fine sandstone. Fuyu oil layer has a good regional cap rock,a good oil source rock of the first section of Qingshankou Formation in its topping.On the basis of regional geological background and petroleum geological condictions of study area,by means of detailed observation of ten exploration wells cored interval about rock type,grain feature,primary sedimentary structure,sedimentary rhythm,fossil organism assemble,clay mineral feature and so on,associating well logging data of sixty-five exploration wells,single well sediment microfacies was divided in the proportion of 1:100. Shallow delta sedimentary facies is recognized,and more two sedimentary subfacies of delta plain and delta front.Delta plain contains five microfacies of water distributary channel, water interchannel,water levee,water crevasse splay and flood plain,and delta front contains four microfacies of underwater distributary channel,water interchannel,underwater levee and underwater crevasse splay,and established commensurable facies model. According to single well sediment microfacies and each sand unit sediment evolution regular pattern,distributary channel grit is the main growing origin sand body,and is divided into water and underwater distributary channel.They display reteporiform shape in plane, north-south approximately and north-northeast in the whole,east-west approximately and northwest-west in portion.From F_â…¢to F_â… ,the depocencer migrates from west to southeast, and the sedimentary water was enlarging inch by inch.Water sedimentary was developed in F_â…¢,its host sand is water distributary channel sand;water sedimentary was developed in the east below of F_â…¡,and its west is underwater;underwater is the important part in F_â… ,and its host sand is underwater distributary channel sand.Using the methods such as thin-section identify,fractional analysis,scanning electron microscopy,X-diffraction,describing reservoir characteristic of Fuyu Oil Layer subtly.The studied area's sandstone is mainly composed with lithic arkose and feldspathic litharenite. The interstitial materials are mainly clay minerals and carbonate cement.The common clay minerals in this area are illite,kaolinite,chlorites,illite and smectite mixed lays.The clay minerals transformation is mainly in the second rapid stage.The carbonate cement are mainly calcite.Compositional maturity of the rock is lower,and texture maturity is moderate. Grain size grade is finer,the reservoir quality is worse.The diagenesis reservoir sandstone mainly underwent comprise compaction,pressolution,cementation,metasomatism, corrosion,dissolution and clay minerals transformation.Sandstone reservoir microstructure of research area is worse,it manifests in low displacement efficiency and high drainage pressure,and bring about bad reservoir infiltrating fluid character and low single well deliverability.According to the data of porosity and permeability,sandstone reservoir of this area is low-lower porosity and lower-lowest permeability.The porosity is chiefly between 10%and 15%,and the permeability is between 0.1×10^-3μm² and 10×10^-3μm².There are many influential factor of physical property which are mainly consist of cement,cover depth,diagenesis and so on.The reservoir was in the A₂ sub-stages of mid-diagenesis period,and give priority to cementation,which are calcite cemented and argillaceous recrystallization infilling aperture,secondary pore is short of good development in this reservoir,and cause porosity and permeability worse.Using the analytical study such as lithology,physical property,electric nature and oiliness characteristic,the lower limit of four characteristics are defined,the lower limit of lithology is silt;the lower limit of physical property is that porosity is 9%,and permeability is 0.1×10^-3μm²;the lower limit of electric nature is that ILD is greater than or equal to 12.0Ω·m,and AC is greater than or equal to 72μs/ft;the lower limit of oiliness characteristic is oil immersion.Using the analysis of precipitation,diagenesis and accumulate,the clascification criteria of low permeable sublayer layer is established.There are four layers in this area which are less permeable,extra less permeable and super less permeable.By means of muti-parameter, reservoir comprehensive evaluation is underway.The bulk parameters are actual porosity, permeability,sandstone integrating thickness,valid sand integrating thickness,sand modular, precipitation facie type and drilled sand level number variation value;the microcosmic parameters are pore throat radius,coefficient of sorting,structure coefficient,secede efficiency and drainage pressure.With the test and analysis of microscope,the reservoir type is low porosity,low-super permeability in Fuyu oil layer.Four types of the reservoir in this area are classified:â… type is low permeable sublayer reservoir,and the comprehensive evaluation value is greater than or equal to 0.7;â…¡is extra low permeable sublayer,and the value is greater than or equal to 0.55,is smaller than 0.7;â…¢is super low permeable sublayer, and the value is greater than or equal to 0.55,is smaller than 0.35;â…£is not infiltrate,and the value is smaller than 0.35.Compared with F_â…¡,F_â… is better,Theâ… andâ…¡are extremely better than others in Fuyu oil layer,andâ…¢is in a small area.By means of large number of real and basic geological documents and core analysis and testing data,the macroscopic characteristics of the reservoirs have been researched in detail, and reservoir synergistic evaluation was completed in Fuyu Oil Layer,thus it has provided basic geological evidence for advantageous target region optimization,the above studied results possess much more important theoretical significance and practical value for forther exploration and exploitation.