RESERVOIR CHARACTERISTICS OF SHAXIMIAO FORMATION IN WEST-ERN SICHUAN BASIN AND EVOLUTION OF PORE DIVERSITY UNDER BIDIRECTIONAL PROVENANCE CONDITIONS
In this paper,X-ray diffraction,cathodoluminescence,scanning electron microscopy,electron microprobe,and other experimental techniques are used to study the characteristics of tight gas reservoirs in the Jurassic Shaximiao Formation in western Sichuan.The study explores the evolution of sandstone pores in the reservoir under bidirectional provenance conditions from the north and south.It discusses the formation of high-quality reservoirs from the perspectives of reservoir evolution and formation mecha-nisms,aiming to provide a reference for efficient exploration of tight sandstone gas in the area.The results reveal that under the influence of southward provenance,feldspar sandstone and lithic sandstone are pri-marily developed in southwest Sichuan,while under the influence of northward provenance,feldspar lithic sandstone and lithic feldspar sandstone are mainly developed in northwest Sichuan.The average porosity and permeability of sandstone in southwest Sichuan are 10.52％and 0.133 4× 10-3μm2,respectively,while in northwest Sichuan,they are 9.74％and 0.526 2×10-3μm2,respectively.The reservoir space of sandstone in western Sichuan is mainly composed of primary intergranular pores and secondary intergranu-lar pores.Compaction plays a dominant role in the reduction of porosity,resulting in a 23.94％decrease in the porosity of sandstone.In contrast,due to the protective effect of chlorite coating,the porosity of sand-stone in southwest Sichuan is reduced by 22.75％,with cementation playing a secondary role in the reduc-tion of porosity.Overall,the porosity of sandstones in northwest and southwest Sichuan decreases by 9.2％and 11.3％,respectively.Conversely,dissolution plays a positive role in increasing porosity,lead-ing to a porosity increase of 5.26％in northwest Sichuan and 4.32％in southwest Sichuan.Comprehen-sive analysis reveals that the present pore characteristics of the Shaximiao Formation reservoir in western Sichuan are the result of multiple diagenetic processes.
Sichuan BasinJurassic Shaximiao Formationreservoir characteristicsmain control factorsdiagenesis
万方数据
维普
