Abstract：By using conventional rock thin sections, casting thin sections, scanning electron microscope and reservoir physical property analyses, combined with parameters such as apparent compaction rate, apparent cementation rate and apparent dissolution rate, this paper quantitatively researched the diagenesis sequence and pore evolution process of low permeability reservoir of one structure in Xihu Sag.The research results show that. (1)The predominant pore types of low permeability reservoir in Xihu Sag are secondary dissolution pores, and intergranular dissolution pore is the main type of secondary porosity. (2)Mechanical compaction effect is the main factor for low permeability, which results in 65% of primary porosity loss, and the dissolution of the secondary dissolution pores improves the reservoir property to some extent. (3)The reservoirs in the research area are at stage A2 of middle diagenesis phase and stage B of middle diagenesis phase. The diagenetic evolution sequence is as follows: ①Brittle particles were broken with the plastic deformation of particles, and local chlorites were edge-cemented; ②Parts of the feldspar and lithic were dissolved in early period, and quartzs of early period were with secondary overgrowth; ③Carbonates were cemented and replaced by quartz, feldspar and so on, and quartz particles were dissolved; ④The dissolution of carbonate, feldspar and cuttings resulted in secondary pores and secondary overgrowth of quartz; ⑤Small quantities of iron calcite had cementation and metasomatism. The results can provide scientific basis for the prediction and evaluation of high quality reservoirs in low permeability reservoirs in Xihu Sag.
2018, Vol. 5 
