Origin and distribution of grain-coating and pore-filling chlorite in deltaic sandstones for reservoir quality assessment

Grain-coating chlorite preserves porosity and permeability through the inhibition of quartz cement whereas pore-filling blocks pore-throats diminishes reservoir quality. The aim this study is to determine origin principal mechanisms which govern distribution grain-coating in Jurassic deltaic sandstones (Tilje Formation, Smørbukk field, Mid Norwegian Shelf). focussed on very high-density sampling for petrographic analysis, from three sections sandstone core same well with contrasting quality, rather than low-density approach typically employed. was gain new understanding specific controls based description, analysis measurements a suite techniques. Results show originated thermally-driven recrystallisation detrital clay coats and/or mineral precursors. Pore-filling has principally derived ductile deformation chlorite-rich Fe-ooids, that were possibly reworked proximal evaporitic setting. precursor material, coats, subsequently chlorite, controlled by relative dominance tidal fluvial processes active during sediment deposition. Optimum found tidal-fluvial moderate influence. pervasive channel deposited periods high discharge, or central turbidity maximum zone; marked an abundance fluid mud. Tidal no influence are pervasively cemented due absence chlorite. good quality occurs heterolithic distributary mouth bar sandstones, however mixing mud- sand-prone facies intense bioturbation reduced permeability. can be used predict field analogous shallow-marine worldwide.