A Study On Pore Structure And Percolation Characteristic Of E₁f₃ Reservoir Of Sha-7 Fault Block In Gaoyou Depression

Pore structure and percolation characteristic of E1f3 reservoir of Sha-7 fault block in Gaoyou Depression have been studied by means of casting sections, SEM, pore image, high pressure mercury penetration, rate-controlled mercury penetration, oil-water relative permeability, oil-water displacement of natural sandstone micromodel, NMR, etc. Their influencing factors and association with physical properties have been also discussed, main controlling factors of physical properties have been analysised from aspects of sedimentation and diagenesis as well. Main achievements are summarized as follows:(1) Intergranular pores(including primary intergranular pores and dissolution intergranular pores)and dissolution pores of framework grains are the main pore types of E1f3 reservoir of Sha-7 fault block, which also had small amount of intercrystal pores and farthing granula fractures. Punctuate constriction throat is the main throat type, lamellar and curved-lamellar throats take second place. Pore-throat assemblage is characterized by large-pore cooperated with wide-throat and moderate-pore cooperated with thin-throat.(2) The positive correlation between oil displacement efficiency and physical properties of the reservoir is not very strong, while oil displacement efficiency is proved to become higher as the throat radius become wider, espetially to radius of the largest interconnected throat.(3) Saturations of moving fluid vary between different samples. It has a obvious positive correlation with permeability. When physical properties show little difference, hydrosialites' type and content become key factors influencing saturation of moving fluid.(4) Mathematical statistic analysis indicates that the control parameters of physical properties are buried depth, secondary porosity, quantum of cementing materials and compaction percentage, followed by grain size and cementation percentage. Performance of E1f3 reservoir of Sha-7 fault block has been improved apparently by corrosion:main pore structure of reservoir in the corrosion zone behave as large-pore cooperated with wide-throat, and the physical properties become better as well as oil displacement efficiency and moving fluid saturation.