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Southern Indus Basin is one of the promising regions in Pakistan as a commercially producing oil and gas perspective. The current research presents the geochemical characterization of the Ranikot Formation shales from Southern Indus Basin based on total organic carbon (TOC), Rock-Eval (RE) pyrolysis, organic petrography, gas chromatography-mass spectrometry (GC-MS), and x-ray diffraction (XRD) analyses. The average TOC of Ranikot shale is 4.6 wt. %, indicating very good hydrocarbon potential. Types III/IV kerogens were identified in Ranikot shale. The maceral data also suggest that the Type of kerogen present in Ranikot shale is dominantly Types II-III, with the minor occurrence of Type IV. The vitrinite reflectance, pyrolysis Tmax and methylphenanthrene indices values specify immature levels of the shales. The normal alkane data reflect that marine macrophyte, algae, and land plants were contributed to the organic matter of Ranikot shales. Dibenzothiophene/phenanthrene ratio (0.11), phytane/n-C18 ratio (0.53), pyrite, and glauconite elucidate that the depositional environment of the Ranikot shale is marine. The XRD analysis of the shale from the Ranikot Formation revealed that it is brittle shale and dominated by 39.5 to 50.9 wt. % quartz. The present study, integration with the US EIA report demarcated the Ranikot Formation influential horizon as a shale gas resource.

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A systematic geochemical investigation of the Laki Formation from the selected regions of Southern Indus Basin Pakistan Basin has been carried out. This paper presents the characterization of hydrocarbon potential, type of kerogen, thermal maturity, the origin of organic matter, depositional environment, and bulk mineralogy of the Laki Formation shales. The total organic carbon (TOC) content of the Laki shale ranges from 0.53 to 2.66 wt. %. The values indicate that Laki shales have fair to very good hydrocarbon potential. Type III kerogen is identified in the Laki shale based on TOC and residual potential (S2) data. Maturity parameters (Tmax & Methyl phenanthrene index) suggest that Laki shales are thermally immature for the generation of hydrocarbons. Normal alkane data and stable carbon (δ13C) isotopic value (-9.67 ‰ PDB) of the Laki shale indicates the predominantly marine origin of the organic matter. Dibenzothiophene/phenanthrene (DBT/P) ratio (0.08), Phytane (Ph)/n-C18 versus Pristane (Pr)/n-C17, and Pr/Ph versus DBT/P data suggest a marine environment of the Laki shale. The marine setting of the Laki Formation shale is further evident by coralline algae and Alveolina oblonga. X-ray diffraction (XRD) data reflect that Laki shale is brittle since it is dominated by high quartz and carbonates.