The Study On Reservoir Comprehensive Evaluation And Productive Advantageous Regions Prediction On Chang6₁ Reservoir In Zhuan Yaowan Area Of Ansai Oilfield,Ordos Basin

Based on the data such as drilling,logging,oil testing and analysis data,this paper carries out research on stratigraphic division and comparison,sedimentary microfacies and sand body distribution analysis,reservoir characteristics and comprehensive evaluation,and main controlling factors of hydrocarbon accumulation through a larger number of core observation,thin slice identification,scanning electron microscope,well log interpretation,high pressure Hg injection and other technologies,and finally optimizes the favorable zones of each small layer of the Chang 6₁ layer in Zhuan Yaowan Area of Ansai Oilfield.?1?According to the marking layer,the characteristics of the cycle and the development of the oil layer,divide the Chang 6₁ layer of the study area into four layers of Chang 6₁^1-1layer,Chang 6₁^1-2layer,Chang 6₁¹-3-3 layer and Chang 6₁² layer,completing the fine division of 427 wells in the whole area.Then through the division and comparison of the drilling wells,a Chang 6₁ layer isochronal stratigraphic framework of the study area is established.?2?According to the research,the Chang 6₁ layer sedimentary system in Zhuanyaowan Area is the delta front subfacies,and it has developed the micro-phases such as the underwater distributary channel,the interdistributary bay,the mouth bar,the natural levee,and the sheet sand.The Chang 6₁² layer and Chang of 6₁^1-2 layer small subaqueous distributary channel sediments are of large thickness and wide distribution.Then,according to the hydrodynamic strength and logging curve shape,the subaqueous distributary channel is subdivided into superimposed rivers and general rivers.The superimposed river channel is the most favorable oil-bearing reservoir sand body in the study area.?3?The Chang 6₁ layer reservoir in Zhuan Yaowan Area is generally a low porosity-extra low permeability reservoir with an average porosity of 11.075%and an average permeability of 0.248×10^-3?m².The pore types of the reservoir are mainly intergranular pores and dissolved candle holes with laminated throat or curved lamellar throat,and the pore structure is complex and variable.The comprehensive researches on petrological characteristics,reservoir physical characteristics,pore type and pore structure characteristics,reservoir sensitivity and pore fluid properties,reservoir seepage physical characteristics,reservoir heterogeneity characteristics are made,and on this basis,reservoir evaluation criteria is established to make a comprehensive evaluation on the reservoir.?4?The Chang 6₁ reservoir type in Zhuan Yaowan Area is mainly lithologic reservoirs.The main sand belt of the subaqueous distributary channel superimposed riverway microfacies is the most favorable sedimentary phase belt for oil and gas enrichment and the chlorite film cementation-intergranular pore diagenetic facies is reservoir-rich diagenetic facies.The differences between sedimentary microfacies and diagenetic facies is the macroscopic factor that explores the difference in well productivity,while the differences in reservoir characteristics caused by heterogeneity is the micro factor.?5?Based on the sedimentary microfacies,reservoir classification,oil layer thickness and test oil yield,etc.,the screening criteria for favorable areas is established.According to the criteria,screen out 3 Class I?5 Class II?2 Class III favorable areas of Chang 6₁² layer and 3 Class I?3 Class II?2 Class III favorable areas of Chang 6₁^1-2layer,which provide reference for oilfield storage and production increase.