Evaluation And Mechanism Of Reservoir In Shanle,Tuha Basin

The evaluation and mechanism of tight oil reservoir have important significance.Based on the sedimentary facies,core observation and well logging,the reservoir within the second member of Jurassic Xishanyao Formation was evaluated using the technologies of XRD and thin section.The effects of tectonic,sedimentary and diagenesis to reservoir quality,and the storage mechanism were discussed.The favorable exploration area was further predicted.The sediment source of the study layer is mainly from the southeast,followed by the northeast in the early stage,and then transferred to the north in the late stage,developing an alluvial fan – delta – swamp – lake depositional system.The main rock types are lithic sandstone and feldspar lithic sandstone,which are mainly consist of debris,quartz and feldspar,showing a low compositional maturity.The diagenetic stages of the reservoir can be classified into B-sub stage of early diagenetic stage and former A-substage of later diagenetic stage,according to the effects of the consolidation,cementation,metasomatism and dissolution.Tectonic faults and fractures formed directly improve the quality of reservoir.The distribution of sedimentary facies control the types and distribution of the reservoir.The secondary porosity caused by the solution of acidic which are formed during the generation of the hydrocarbon plays an important role to increase the reservoir quality.The lower limit of porosity is 6% in this study.Based on the physical properties,the reservoir can be further divided into four classes,in which the most favorable I and II classes are located to the northwest of Le-5 well and west of Le-16 well beside the area discovered,which may be the next exploration targets.