THE DIFFERENCE OF TIGHT SANDSTONE RESERVOIR AND FORMATION MECHANISM OF HIGH-QUALITY RESERVOIR IN THE XUJIAHE FORMA-TION IN THE TRANSITIONAL ZONE BETWEEN CENTRAL AND WESTERN SICHUAN BASIN
THE DIFFERENCE OF TIGHT SANDSTONE RESERVOIR AND FORMATION MECHANISM OF HIGH-QUALITY RESERVOIR IN THE XUJIAHE FORMA-TION IN THE TRANSITIONAL ZONE BETWEEN CENTRAL AND WESTERN SICHUAN BASIN
Through comprehensive analysis of cast thin sections,scanning electron microscopy,physical properties,and high-pressure mercury injection,this study delves into the characteristics of tight sand-stone reservoirs within the Xujiahe Formation in the southern Jianyang area and the northern transitional zone between central and western Sichuan.The aim is to uncover the main controlling factors and forma-tion mechanisms of high-quality reservoirs.Findings indicate differences in rock composition between the north and south regions of the Xujiahe Formation due to varying provenance influences.In the Jianyang ar-ea,the quartz content is low while plastic clast content is high.Conversely,the northern region exhibits higher quartz and rigid clastic particle content,with relatively developed chlorite coatings.Physical prop-erty analysis reveals peak porosity and permeability ranges,with the southern Jianyang area showing po-rosity between 6％to 8％and permeability from 0.01 × 10-3μm2 to 1.00×10-3μm2,and the northern area displaying porosity between 4％to 8％and permeability from 0.01 × 10-3μm2 to 10.00× 10-3 μm2.Reser-voir space in the southern Jianyang area primarily comprises feldspar and debris solution pores,while the northern area predominantly consists of residual primary intergranular pores,feldspar solution pores,and debris solution pores.High-pressure mercury injection tests reveal a wider distribution range of pore throat radius and better pore throat connectivity in the northern area compared to the southern area.Compaction primarily reduces reservoir porosity in both northern and southern areas,particularly in the southern area with a high content of plastic clasts.Dissolution serves as the main porous diagenesis,especially prominent in the southern Jianyang area where secondary dissolution pores dominate the reservoir space.The develop-ment of chlorite is correlated with rock composition and provenance,with chlorite cementation mainly oc-curring in the northern area,inhibiting intergranular cement growth and resisting compaction to some ex-tent.This study holds practical significance for further oil and gas exploration within the Xujiahe Forma-tion in the study area,providing valuable insights into reservoir characteristics and formation mechanisms.
关键词
优质储层/主控因素/致密砂岩/须家河组/四川盆地
Key words
high quality reservoirs/main controlling factors/tight gas sandstone/Xujiahe Formation/Si-chuan Basin
万方数据