FORMATION MECHANISM OF LOWER PALEOZOIC CARBONATE RESERVOIRS IN ZHUANGHAI BURIED HILL

Based on an integrated study of geologic,geochemica! and geophysical data,original sedimentation,karslifica-lion,dolomitization and tectonic disruption are recognized to be the main mechanisms for formation of the Lower Paleozoic carbonate reservoirs in Zhuanghai buried hill of Jiyang depression.The initial sedimentation controls the nature of the limestone reservoirs! the karstification improves the poroperm characteristics of the reservoirs and results in carbonate karst reservoirs of high quality;the dolomitization leads to the formation of dolomite reservoirs of high quality;the primary porosity is a necessary condition for the formation of dolomite reservoirs;the contraction of fragments during dolomitization leads to the formation of pores in the dolomite reservoirs;and the fractures are the base for strong karstification and the formation of fractured or frac-tured-vuggy reservoirs.In plane view,the fractures and vuggs in the Lower Paleozoic carbonate reservoirs are in zonal distribution in the study area.