Quantitative simulation of the densification process of sandstone reservoir in the Xu 3 Member of Xujiahe Formation in western Sichuan Depression, Sichuan Basin

Abstract

In order to clarify the densification process and quantitatively restore the porosity evolution of the Xu 3 Member sandstone reservoir in western Sichuan Depression, the diagenesis of the Xu 3 Member was system atically analyzed using thin sections, scanning electron microscope and fluid inclusion analysis. Meanwhile, the relationship between diagenesis and porosity evolution was discussed.Based on the study of formation burial history and thermal evolution history, a mathematical model of porosity evolution for the Xu 3 Member sandstone was established to clarify the densification process of sandstone reservoir using the principle of effect simulation, that is, the specific diagenesis was not simulated, but the comprehensive superposition results of various diagenesis were simulated through geological parameters.It found that lithic quartz sandstone and lithic sandstone were mainly developed in the Xu 3 Member, and sand stone underwent compaction, cementation, dissolution and others. Among them, compaction and cementation are the main destructive diagenesis and occur in the whole evolution process, while dissolution is the main constructive diagenesis and only occurs in a specific evolution stage with window characteristics.Based on the current observation of the relationship between porosity and depth of sandstone, the sandstone had undergone compaction and cementation, corrosion, and compaction and cementation after corrosion.As a result, the porosity evolution could be divided into three stages: normal compaction stage, pore increasing stage during corrosion andnormal compaction after corrosion.Furthermore, the porosity evolution could be divided into porosity decreasing model and porosity increasing model.These two models were superimposed on the three stages of porosity evolution, and a three-stage piecewise function characterized the porosity evolution was proposed.Using this function, the total porosity evolution simulation of sandstone reservoir could be realized.Simulation results found that the Xu 3 Member in western Sichuan Depression was dominated by early densification due to compaction and early cementation using the proposed quantitative model.

Keywords

• tight sandstone
• reservoir diagenesis
• effect simulation
• porosity evolution
• xu3 member
• western sichuan depression