Two types of sedimentary facies(bioherm and organic bank) are developed in Liuhua 11-1 oilfield.They can be subdivided into 6 microfacies,including coralgal reef,coral reef,coralgal-coral reef,foraminiferal bank,bioclastic bank and coralgal debris-foraminiferal bank.Core observation and thin section analysis indicate that the diagenesis of reef complex in sea floor diagenetic environment,fresh water diagenetic environment and regional underground water-buried diagenetic environment include cohesion,dissolution,cementation,compaction-pressure solution,recrystallization,dolomitization and "chalkification",etc.Based on the results of sedimentary facies analysis and the effects of various stages of diagenesis on poroperm characteristics of reservoirs,the sedimentary-diagenetic evolution of reef limestone reservoirs are divided into 8 periods,i.e.the early reef formation,early exposure-dissolution,late reef formation,middle exposure-dissolution,early reservoiring,late dissolution,late reservoiring and regional groundwater dissolution periods.This unique evolution pattern constitutes vertically 8-layer reservoir architecture,including the alternating of 4 high porous and permeable layers and 4 medium-low porous and permeable layers.Cementation is considered a major diagenetic factor in the 4 medium-low porous and permeable layers,namely layers A,B2,C and E,which are relatively tight and have widely developed intercalations.The layers B1,B3 and D,being in percolation environment,have been turned into high porous and permeable layers through dissolution,while the high porous and permeable layer F formed by further dissolution of regional groundwater is an aquifer.
