Study On The Diagenesis Of Reservoir In He 8-Shan 1 Section Western Sulige Gas Field

Sulige gas field is one of the super large gas fields in China.It is located in Suligemiao area in the middle and north of Ordos Basin.Its reservoir has a huge exploitation potential,but the reservoir has the characteristics of low porosity,low permeability and low homogeneity.With the development of the exploitation of the gas field,it is urgent to study the main gas bearing reservoir.Therefore,the study of reservoir characteristics and pore quantitative evolution characteristics is of great practical significance for the exploration and development of he8-shanl oil and gas reservoir in Western Sulige.In this paper,the diagenesis and reservoir characteristics of the study area are studied in detail by using scanning electron microscopy,cathodoluminescence,fluid inclusion temperature measurement,mercury injection and other analytical and testing techniques,and the evolution process of reservoir porosity in the study area is quantitatively restored by the constraints of diagenetic sequence.In the reservoir of the study area,the clastic particle size is mainly medium coarse,with medium sorting and roundness,and high component maturity;the pore types are mainly matrix dissolution pore,debris dissolution pore and intergranular pore of authigenic mineral,with low porosity and permeability as a whole.The reservoir in the study area has experienced a series of complex diagenesis and stages,such as compaction,cementation,pressure dissolution and dissolution,in which cementation is stronger than compaction.The diagenesis of He8 and shanl members in the study area has gone through syngenetic stage,early diagenetic stage and middle diagenetic stage,but not into late diagenetic stage.From syngenetic stage to early diagenesis stage B,the compaction is strong,and the cementation is represented by the formation of chlorite film and the filling of argillaceous calcite;in middle diagenesis stage a,quartz edge and kaolinite begin to form gradually,organic acid begins to produce,diagenesis environment gradually turns to acid,pressure dissolution is gradually obvious,and secondary dissolution pores increase;in middle diagenesis stage B,the organic acid content is large The diagenetic environment began to change from weak acid to alkaline.With compaction,kaolinite and illite further block the pores,and calcite began to appear in large quantities in the late stage,which can replace quartz and other minerals.By studying the evolution of diagenesis,the change of porosity in different stages is determined,and the porosity can be quantitatively restored to each stage of diagenesis.