Diagenesis and Controlling Factors of Kalashayi Clastic Reservoir in South of Tahe Oilfield

The Kalashayi sandstone reservoir deposited in tidal-flat facies. Main diagenesis include compaction, cementation and dissolution, which compaction belongs to middle-weak, point to linear contact between grains and pore-space cementation by carbonate rocks; dissolution features that feldspar grains and carbonate cementation’s dissolution. The reservoir is mesopore and medium permeability reservoir in a current depth of 4800-5300m. The reason cause this mesopore and medium permeability reservoir are considered as the following factors. The physical properties of reservoirs are mainly controlled by sedimentary microfacies and diagenesis. The strong tidal channels and tidal creaks current leads to the composition of rock mineral pure, quartz content is high, the grains coarser, good sorting and low matrix. The early compaction was so little that some pores were conserved in carbonate cementation, and in the later diagenetic process, carbonate cementation were corroded to secondary pores.