English abstract
This study attempts to constrain the role and distribution of diagenetic alterations and their subsequent impact on reservoir quality evolution in relation to depositional environment (glacio-fluvial and glacio-lacustrine) of Carboniferous Permian Al Khlata Formation sandstones in Wadi Dayqah, North Oman. However, this study reveals that these sandstones have undergone various diagenetic alterations during eo- and mesogenesis. Eogenetic alterations include: (1) mechanical compaction of framework grains due to high rate of sedimentation (11) cementation by calcite and (iii) kaolinitization of mica, which are attributed to influx of meteoric water during the melting of glacier Mesogenetic alterations include: () illitization of mica (ii) chemical compaction and (iii) formation of quartz overgrowths. Chemical compaction is the most dominant and abundant found in both glacio-fluvial and glacio-lacustrine sandstones and affected mostly fine- to medium-grained sandstones. Compaction was more important than cementation in destruction of primary porosity enhanced by presence of mica along the grain contacts of detrital quartz, Quartz overgrowths found mainly in glacio-fluvial sandstones and are absent where illitized mica present around the detrital quartz grains. Microcrystalline quartz occurs in traces and precipitated as quartz cement at the grain contact of detrital quartz. Calcite cement is less common but observed in both glacio-fluvial and glacio-lacustrine sandstones. Illitized mica is found extensively whereas kaolinite found in traces in glacio-fluvial and glacio-lacustrine system. All these diagenetic alterations played a role in destroying the porosity of Al Khlata Formation sandstones. The findings of this work can help predicting the distribution of diagenetic alterations and their impact on reservoir properties of sandstones.
