Implication of the diagenetic evolution for the diagnosis of reservoir potential of the Amb Formation, western Salt Range, Pakistan
Keywords:
Amb Formation; Late Permian; Siliciclastic-carbonate lithofacies; Western Salt Range; Pakistan.Abstract
The diagenetic fabric of the Amb Formation in the western Salt Rang, Pakistan is presented as a tool for understanding its diagenetic potential. Three key stratigraphic sections, namely, Zaluch Nala, Ghundai Nala and Kalawahan Nala that represent outcrop exposure of 50.1m, 16.5m and 30.5m respectively, were taken into account. A total of 58 siliciclastic-carbonate rock samples were processed from these three key stratigrahic sections. The facies analysis revealed that deposition of the Amb Formation occurred in the siliciclastic dominated shelf platform, evident from facies AMB 1-AMB 5. These facies revealed the signs of diagenetic alteration caused by the micritization, dissolution, cementation, pyritization, recrystallization, physical and chemical compaction, and fracturing. Identifications of different cement types helped to categorize different phases of digenesis as early marine, shallow burial and deep burial, which in turn helped in the hydrocarbon reservoir potential within each facies e.g. the AMB 1 and AMB 2 have a fair porosity while the AMB 3A, AMB 3B and AMB 4 have poor porosity. The AMB 5 has good porosity. These porosities fluctuated within studied sections and are different from the Kalawahan Section: AMB 1, AMB 2, AMB 3A, AMB 3B and AMB 4 which have poor porosity and Ghundai Nala: AMB 1 and AMB 3A are absent, AMB 3B has fair porosity, AMB 4 has poor porosity.
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