| Qingshui depression is the largest hydrocarbon-generating depression in Liaohe depression,and many oil-rich gas zones are formed in the lateral migration of oil and gas.In recent years,the situation of increasing and stabilizing production in Liaohe oilfield is becoming more and more serious,and some of the geological reserves reported in Liaohe oilfield have been divided into unused reserves blocks because of various reasons.Shuguang oilfield is the old oil area with the longest mining time and the highest contribution of oil and gas production capacity.Dujiatai reservoir in Shu103 block is one of the blocks with low internal reserves and has a good material base.Based on the theory of reservoir geology,underground geology,sequence stratigraphy,logging and reservoir description,combined with the data of drilling,logging,production test,this paper studies the reservoir sedimentary microfacies,reservoir geological characteristics,reservoir electrical characteristics and heterogeneity on the basis of the regional geological characteristics analysis and stratigraphic division and comparison.The research results can provide the geological basis for the the further development of the pool.On the basis of regional geological characteristics analysis,the strata are further subdivided.According to the sequence formation,sedimentary evolution and logging curve characteristics of Dujiatai reservoir in the study area,two marker layers and two auxiliary marker layers were identified.Dujiatai reservoir was divided into three oil reservoirs:Du I,Du II and Du III.The logging curve characteristics of each comparative marker are clear in the study area,which provides a reliable isochronous stratigraphic framework for the study of sedimentary,reservoir and reservoir characteristics.On the basis of stratigraphic division and contrast and sedimentary backgroundanalysis,the sedimentary and sand distribution characteristics of Dujiatai reservoir are studied.It is considered that the Dujiatai reservoir in the study area is fan delta front subfacies,and the material source is from the southwest of the work area.The reservoir types are mainly subaqueous distributary channel and mat sand microfacies,among which the subaqueous distributary channel microfacies sand body is the best reservoir.The distribution of sand body is controlled by the subaqueous distributary channel facies belt,which is mainly developed in the north-west-south-east strip.The sedimentary and sand distribution characteristics of Dujiatai reservoir in the study area are studied in detail through sedimentary analysis and reservoir prediction.Dujiatai reservoir in the study area is fan delta front subfacies,the material source is from the southwest of the work area.The reservoir types are mainly subaqueous distributary channel and sheet sand microfacies,among which subaqueous distributary channel microfacies are the best reservoirs.The distribution of sand body is controlled by the subaqueous distributary channel facies belt,which is mainly developed in the north-west strip.The thickness of sand body from the center of distributary channel to the lateral edge is reduced rapidly.The petrological and reservoir performance characteristics of Dujiatai reservoir in this area are analyzed by analyzing the data of core and sheet.It is considered that the reservoir lithology of this area is mainly composed of mud-bearing fine sandstone,medium-fine sandstone,fine sandstone,medium sandstone and unequal grain sandstone,and the clastic mineral composition is mainly quartz and feldspar.The average porosity of the reservoir is20%,and the average permeability is 82.44×10-3?m2,which belongs to the middle porosity-low permeability reservoir.The pore types of reservoir are intergranular pores,dissolution pores,cementation or filling intergranular pores,among which the primary intergranular pores are the pore types that play a major role in oil and gas storage.According to the morphological characteristics of mercury pressure curve,the reservoir can be divided into three types.diagenesis includes compaction,cementation and dissolution.dissolution increases the pore size of the reservoir and improves the physical properties,while compaction and cementation make the pore smaller and the physical properties worse.Diagenesis affects both reservoir physical properties and pore structure.Based on the study of the"four properties"of reservoir,the model of reservoir parameter calculation and the identification standard of oil-water reservoir are established.On this basis,the heterogeneity characteristics of reservoir and its influencing factors are studied.Based on the above research results,the control effect of sedimentation and diagenesis on reservoir is analyzed,and the distribution characteristics of reservoir are described.The controlling effect of sandstone thickness,reservoir physical property and pore structure on reservoir distribution was analyzed.The results show that the favorable reservoir of Dujiatai reservoir in this area is mainly developed in Du I and Du II reservoir groups,among which Du II reservoir group is the most developed.The above-mentioned parts can be used as a favorable target for further development. |
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