Abstract: Abstract: To study the diagenesis, diagenetic facies (point, line, plane) and favorable reservoirs of of Es1-2, casting thin sections, scanning electron microscope(SEM), electron backscatter differaction(EBSD), cathode luminescence(CL), physical properties data and sedimentary microfacies analysis have been applied to the sampled drilling wells. The result indicates that: influenced by synsedimentary volcanic eruption and hydrolysis, diagenesis in alkaline condition took place in Es1-2 reservoir, forming ctenoid dolomite, potassium feldspar albitization and quartz dissolution. Meanwhile the layered igneous rock protected the underlying stratum by weakening the compaction. Besides, diagenesis in acid condition followed, such as dissolving feldspar and debris. Dissolved pore accounts for 567% percentage(average value) in Es1-2 reservoir. Adopting composite naming way as the diagenetic facies of casting thin section, single well and planar region are named following the “(microfacies) sandstone position+main diagenesis phenomenon+ pore types”, and classified into three types: the underwater distributary channel sand body flankfinesilt sandsiderite cementationlow porosity facies, the delta frontmediumfine sandundercompactiondolomite involucrumdissolved pore facies and the distal volcanic lavatufaceous mediumfine sandtufaceous cementationtight facies. The identification of oil reservoir and oilwater reservoir by well logging interpretation matched the undercompactiondolomite involucrumdissolved pore facies. In this research, the most prospected reservoir favors the delta frontmediumfine sandundercompactiondolomite involucrumdissolved pore facies.

Key words: Huanghekou depression, BZ34 area, Es1-2 reservoir, diagenetic facies, reservoir prediction