| The formation of favorable porosity not only is related to sedimentation,tectonic movement and hypergenesis,but also related to the diagenetic process of water-rock interaction.Pore fluids can cause the change of mineral solubility result in mineral dissolution or precipitation in clastic reservoir,and the formation of dissolution secondary pores in sandstone reservoir is closely related to the change of mineral solubility of clastic skeleton grains in geological fluids.Water-rock interaction cause the variation of mineral solubility at different temperature and pressure conditions,which lead to the spatial difference of the formation of dissolution secondary pores in reservoir sandstones and affect the heterogeneity of reservoir properties.The dissertation focused on the case study of Es4 of Minfeng sag in Dongying Depression,based on a conjunction of core observation,thin section identification,fluid inclusion analysis,clay mineral analysis and other methods,the systematic study focuses on diagenesis and diagenetic fluid.Diagenesis involved less compaction,cementation,metasomatism,dissolution.Dissolution favor the formation of secondary pores,there are some grain inner pores which are produced by the dissolution of quartz,feldspar,carbonate minerals.By means of fluid inclusion temperature measurement technology,tests conducted on homogenization temperature of the single fluid inclusion in the core samples of cores along the internal fissures of grains,and the results show that the reservoir diagenetic fluid of number 4 of Sha Hejie formation in Minfeng sag mainly has three acidic siliceous cement,homogenization temperature range shows presence of acidic fluids.In addition,pH value occur acidity-alkaline fluid alternating process in the depth range of number 4 of Sha Hejie formation in Minfeng sag,and convert to alkaline fluid at last.It chooses the temperature and pressure condition of Fengshen1,Fengshen3,Fengshen4 and Feng8 in number 4 of Sha Hejie Formation which does simulation experiments about mineral dissolution and precipitation.The results show,in all the water types of simulation experiments,quartz and feldspar are dissolved under the acidity and neuter condition,and quartz,feldspar solubility increase with temperature rising,the corrosion phenomenon of quartz and feldspar under the acidity condition is more clear than that under the neuter condition;the corrosion phenomenon of calcite only exit the Na2SO4 type-water and MgCl2 type-water in Fengshen 3,which is clear under the acidity and neuter condition,and calcite solubility increase with temperature rising;it takes place the cementation of calcite in the CaCl2 type-water of Fengshen1,the NaHCO3 type-water of Fengshen 4,the CaCl2 type-water of Feng8,the cementation of calcite ehance with temperature rising.It can be seen,temperature,pH value and the internal component of differences water are the leading factor influencing mineral solubility.Through the experimental results compared with the Matching Relationship of diagenesis stage,it can be found that,the experimental simulation results of Fengshen1,Fengshen3,Fengshen4,Feng8 are had excellent relevance with diagenetic phenomenon of diagenetic stage corresponding.Under the condition of degree of mineralization,seepage velocity,burial time,degree of porosity,mineral density and other factors,mathematical model for calculating rate of secondary porosity and cementation is established based on mineral solubility and growth rate.The results show,All of quartzes,feldspars are converted to secondary pores,and calcite is less cemented at about 145? in Fengshen1;Within temperature range,the MgCl2 type-water of Fengshen 3,the NaHCO3 type-water of Fengshen 4,the CaCl2 type-water of Feng8 and 171? have maximum contribution to the reservoir property,the maximum value is 3.3266%,3.8949%,2.5235%,respectively,these are the best type-water and temperature which is the most conducive to the development of secondary pore zone in the depth range of stimulation experiments.In general,the high temperature is the most conducive to the development of secondary pore zone in the depth range of stimulation experiments,that is to say,Fengshen1 in the depth range of 4329.8-4343 m and Fengshen3,Fengshen4,Feng8 in the depth range of 4753.2-4784.3m are the most conducive to the development of secondary pore. |
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