莺歌海盆地东缘中深层超压低渗储层特征与优质储层形成机理OA

With the increasing exploration degree in mature areas such as the Dongfang Area and Ledong Area of the Yinggehai Basin,as well as the main stratigraphic series such as the Miocene Yinggehai and Huangliu forma-tions,the basin has gradually entered a stage of exploration,on which the medium-deep overpressured low per-meability fields are focused.To address issues in the eastern margin of the basin,including relatively low explora-tion degree,unclear understanding of the characteristics of medium-deep reservoirs,and the genesis of high-qual-ity reservoirs,the core and microscopic thin-section observations,logging data,and various types of analytical and test data were analyzed in detail.Eight major categories and 16 subcategories of lithofacies in the medium-deep layers of the eastern margin of the Yinggehai Basin were identified.The medium-deep sandstone reservoirs were found to be characteristic of"ultra-low porosity,ultra-low permeability,and dominance of secondary pores".Six diagenetic facies of medium-deep reservoirs and 23 comprehensive lithofacies-diagenetic facies types were classi-fied.The mechanism of high-quality reservoir formation was dominated by secondary pores following specific-ally the rule of"reservoir control by dual facies,and pore preservation by overpressure and hydrocarbon char-ging".The theory on sedimentary-diagenetic exploration for medium-deep,ultra-low pressure and low-permeabil-ity reservoirs was improved,which provided a theoretical support and technical guidance for exploration break-throughs in the medium-deep,ultra-low pressure and low-permeability fields of the eastern margin of the Yingge-hai Basin.