Jurassic Continental Shale In Yuanba Area Reservoir Quantitative Characterization And Reservoir Capacity Evaluation

Shale gas is a kind of unconventional oil and gas with huge resources.The pore structure of shale reservoirs controls the occurrence state and enrichment degree of shale gas.It is of great significance to optimize shale gas sweet spots and guide shale gas exploration and development.In this paper,the Jurassic Qianfoya Formation and the Da’anzhai Member of the Ziliujing Formation in the Yuanba area are used as the research objects.Through data collection,core observation and description,optical section identification,whole-rock XRD diffraction,total organic carbon analysis,cheese Root microscopy and vitrinite emissivity experiments were used to classify petrofacies,and combined with wetting angle measurement,spontaneous imbibition,field emission scanning electron microscopy（FE-SEM）,gas adsorption experiments,and high-pressure mercury intrusion experiments to analyze different rocks Favorable reservoir facies were evaluated based on facies characteristics.The Qianfoya Formation is dominated by type II₂ kerogen and type III kerogen,and a small amount of type II₁ kerogen exists,with an average TOC content of 1.12%.The mineral composition is mainly quartz and clay minerals,with a small amount of carbonate minerals.Type II₂ kerogen and type III kerogen are mainly in this section,with an average TOC content of 1.07%,and a carbonate mineral content higher than that of the Qianfoya Formation;the organic matter maturity is in the mature-high maturity stage,which is conducive to the development of shale gas.enrichment.The Qianfoya Formation and the Da’anzhai Member are divided into 6 kinds of lithofacies,and the storage capacity of different lithofacies is mainly controlled by the mineral composition,the complexity of pore structure and the geochemical characteristics.The two-factor evaluation method is used to quantitatively characterize the storage capacity of different lithofacies.The parameter value of the storage capacity of the organic-rich lamellar clay shale is 0.552,which belongs to grade II,and the parameter value of the storage capacity of the organic-rich layered clay shale is 0.552.It is 0.507,which belongs to grade II,the organic layered mixed shale reservoir capacity parameter value is 0.486,which belongs to class III,and the organic layered siliceous shale reservoir capacity parameter value is 0.347,which belongs to class III,and the organic laminar clay is poor.The shale storage capacity parameter value of 0.525belongs to grade II,and the organic-poor massive mixed shale storage capacity parameter value of 0.286 belongs to grade III.The lithofacies of the Qianfoya Formation and the Da’anzhai Member of the Ziliujing Formation are divided,and the favorable reservoir intervals of the Qianfoya Formation are mainly distributed in the upper part of the second and first members of the Qianfoya Formation;the favorable reservoir intervals of the Da’anzhai Member of the Ziliujing Formation are mainly distributed in Sophomore sub-segment.