Abstract:

Reservoir sandstones of  the Paleogene Funing Formation  in Yaotan Area of Jinhu Depression mainly consist of  lithic
arkose and arkose, with medium compositional maturity and median-high  textural maturity. The Funing Formation  reservoir
sandstones  in Yaotan area are  in  the A stage of epigenesis,  the main diagenesis of which  includes compaction, cementation,
dissolution, and replacement. Diagenesis and  tectonic movement  influence  the reservoir physical properties  together, especially
affect the porosity and permeability of the reservoir in the study area. Compaction and cementation rapidly decrease the porosity
and permeability of  the reservoir as well as  the whole reservoir quality, while dissolution can  improve  the reservoir quality and
cause the development of secondary pores. Compaction in the reservoir of the study area mostly show as brittle fractures of rigid
particles, compressional deformation of plastic particles,  rigid particles embedding  into plastic particles,  linear and concave-
convex contacts between particles, and  the obvious directional alignment of detrital grains. Dissolution mainly present as  the
dissolution of carbonate minerals, with  the sements between detrital grains mostly being authigenic caly minerals, carbonate
minerals and authigenic quartz. The replacement in the study area mainly show as the replacement between the carbonate cements
and quartz, the feldspars and lithic debris, or inside the carbonate cements. The tectonic movement can partly improve reservoir physical properties in the study area.

Key words: Yaotan area；authigenic clay mineral；diagenesis；tectonic movement；porosity；permeability