Study On Diagenesis And Pore Quantification Of Shan2₃ Tight Sandstone Reservoir In Suide Area

In this paper,the tight sandstone of Shan2₃ in Shanxi Formation of Suide area is studied.Through the observation of the field profile and the drilling core system,combined with laboratory tests,the material composition,reservoir space and physical properties,as well as diagenesis and diagenetic facies,of the sandstone reservoir were studied.The controlling factors of reservoir diagenetic facies and the influence of diagenesis on pore development are discussed.The main understandings are as follows:?1?The material composition characteristics of Shan2₃ tight sandstone in Shanxi Formation in the study area were clarified.Its rock type is mainly quartz sandstone,followed by lithic quartz sandstone with the least lithic sandstone.The main crumbs are quartz and cuttings;the main heterogeneous groups are clay minerals and illite volcanic dust;the types of cement are various,mainly siliceous and kaolinite.?2?The space types of sandstones reservoir of Shan2₃ in the study area were summarized,and the pore structure characteristics were quantitatively studied.The pore types are dissolving pore,residual intergranular pore,intergranular pore,etc.,and three types of pore combinations are identified:residual intergranular pore,intergranular pore and a small amount of dissolving pore,dissolving pore,intergranular pore and a small amount of residual intergranular pore,and dissolving pore with intergranular pore.Fractal dimension study and quantitative characterization of Shan2₃ different sandstone reservoirs pores in the study area were carried out,and it was believed that there were great differences in the complexity of the pore structure of different sandstone types.The pore structure of quartz sandstone is the simplest,followed by lithic quartz sandstone,and the pore structure of lithic sandstone is the most complex.?3?The diagenesis types of Shan2₃ sandstone reservoirs in the study area are explained.The sandstone reservoirs have undergone the transformation of diagenesis such as compaction,compaction,cementation,dissolution,metasomatism and fracture,reaching the middle diagenetic stage B-late diagenetic stage,and the diagenetic evolution sequence is defined.?4?The diagenetic facies types of Shan2₃ sandstone reservoirs in the study area were quantitatively divided and the controlling factors were discussed.According to the visual compaction rate,visual cementation rate,visual dissolution rate and microcracks rate,the diagenetic comprehensive coefficients of tight sandstone reservoir in the study area were calculated,which were divided into four types diagenetic facies,including medium compaction with dissolved pore and residual intergranular pore diagenetic facies,medium compaction with intercrystalline pore and residual intergranular pore diagenetic facies,strong compaction with dissolved pore diagenetic facies and strong compaction with microporous diagenetic facies.The spatial distribution of the diagenetic facies is defined,and it is considered that it is mainly controlled by sedimentary environment,lithology and diagenesis.?5?The influence of diagenesis on pore development of Shan2₃ sandstone reservoir in the study area was discussed.The effects of diagenesis on pore development were quantitatively described by compaction,cementation and dissolution,and the effects of diagenesis on pore development were analyzed.There is a negative correlation between the reservoir comprehensive diagenetic coefficient and pore fractal dimension,which reflects the correlation between diagenetic intensity and pore complexity,and provides a reference for the diagenetic facies classification according to lithology and fractal dimension.