Diagenesis and reservoir quality of the Lower Cretaceous Quantou Formation tight sandstones in the southern Songliao Basin, China

摘要: Abstract The Lower Cretaceous Quantou Formation in the southern Songliao Basin is typical tight oil sandstone China. For effective exploration, appraisal and production from such a sandstone, diagenesis reservoir quality must be thoroughly studied first. has been examined by variety of methods, including core thin section observation, XRD, SEM, CL, fluorescence, electron probing analysis, fluid inclusion isotope testing quantitative determination properties. sandstones are mostly lithic arkoses feldspathic litharenites with fine to medium grain size moderate good sorting. dominated feldspar, quartz, volcanic rock fragments showing various stages disintegration. properties quite poor, low porosity (average 8.54%) permeability 0.493 mD), small pore-throat radius 0.206 μm) high displacement pressure (mostly higher than 1 MPa). reservoirs have undergone significant diagenetic alterations as compaction, feldspar dissolution, quartz cementation, carbonate cementation (mainly ferrocalcite ankerite) clay mineral alteration. As onset time, emplacement was prior but posterior dissolution. smectite illite reaction solution at stylolites provide most important silica sources for cementation. Carbonate cements increase towards interbedded mudstones. Mechanical compaction played more role destroying K 1 q 4 reservoirs. Mixed-layer illite/smectite reduced significantly, while chlorite preserved since it tends wet so that later can inhibited some extent. It likely occurred formation (with close 10%). However, thicker bodies (more 2 m) constitute potential hydrocarbon