Pore-preserving Mechanism of Chlorite Rims in Sandstone-example from the P3w Formation of Jinlong Area, Junggar Basin

Summary Deeply buried sandstone reservoir in the Jinlong area, northwestern Junggar Basin is characterized by high porosity and well developed grain-coating chlorite. However, relationships between the two characteristics are still understudied. The goal of this study are: (1) examining the composition, structure, and distribution of the authigenic chlorite; (2) timing of chlorite growth; and (3) relationships between grain-coating authigennic chlorite and reservoir evolution. The results of the research are shown as followings: (1) The grain-coating chlorite of sandstone in upper Urho formation in the study area is Fe-rich chlorite which has the same component as that of marine sandstone. (2) Petrographic relationships indicated grain-coating chlorite grew mainly before the beginning of quartz cementation, laumotite cementation and feldspar grain dissolution but after mechanical compaction.(3) It can be inferred that chlorite coatings inhibit quartz cementation by reducing the number of individual growth sites present per sand grain.