超深层致密砂岩储层孔隙结构特征及分类评价OA

The second member of Kalazha Formation of Jurassic in Hutubi Region has frequently a-chieved breakthroughs in oil and gas discoveries,becoming the primary producing layer for increasing reserves and boosting production in the southern margin block of the Junggar Basin.This study conduc-ted qualitative description and quantitative analysis on reservoir pore structures in the second member of Kalazha Formation,using core photographs,cast thin sections,scanning electron microscopy,high-pressure mercury injection,and imaging logging.And the reservoir was classified and evaluated based on its pore structure.The results show:the reservoir lithology of the second member of Kalazha Forma-tion is predominantly composed of medium to fine-grained sandstones.Abnormal overpressure and coarse-grained texture are key factors for the preservation of residual intergranular pores,while high matrix content is the primary reason for the generally poor initial pore structure.Using main flow radius as the characterization parameter,reservoir pore structures are divided into three types.Type Ⅰ reser-voirs exhibit the best physical properties,with the dominant flow pore-throat radius generally greater than 0.3 μm.Type Ⅱ reservoirs have average physical properties.The dominant flow pore-throat radi-us range from 0.1 to 0.3 μm.Type Ⅲ reservoirs feature a relatively homogeneous microscopic pore structure.The dominant flow pore-throat radius are generally less than 0.1 μm.Type Ⅰ and Ⅱ reser-voirs exhibit superior pore structures and are prioritized for further development.The logging evaluation model which established based on the pore structure classification exhibits a strong correlation with pro-ductivity.Type Ⅰ and Ⅱ reservoirs are identified as favorable exploration targets.These findings pro-vide significant guidance for the efficient development of Jurassic oil and gas reservoirs in the Hutubi Ar-ea.