Sedimentology and organic geochemistry of potential source and reservoir rocks of the Central Punjab, part of the Indus Basin

Rahmat Ali Gakkhar

    Research output: ThesisDoctoral Thesis

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    Abstract

    Biostratigraphy, sedimentology and hydrocarbon potential of Jurassic and Cretaceous strata of the Punjab Platform were studied, in order to enhance the success rate of hydrocarbon discovery. Two wells were investigated (Ali Sahib and Amir Wali), both drilled to 2050 m depth. The oldest stratigraphic unit in both wells is the Jurassic Datta Formation (mainly sandstone, shale, claystone), followed by the Jurassic Samana Suk Formation. Main lithologies of this formation in Ali Sahib Well: limestone, shale, claystone, sandstone; in Amir Wali Well: limestone. Intensive tropical weathering conditions (seasonal climate) in the provenance area is suggested for the (probably continental) sediments of the Datta Formation, which are comprised mainly by kaolinite-rich shales (occurrence of boehmite), and a minor portion of mature quartz arenite at the top. A fluvio-deltaic sedimentary environment is indicated by the clastic sediments of the Samana Suk Formation. The carbonate sediments of the Samana Suk Formation and the Chichali Formation were deposited in outer deeper shelf region of a carbonate ramp setting, as documented by the mixing of shallow marine carbonate clasts and deep water organisms. The Chichali Formation, which is mainly clastic in the Punjab Platform, was considered as early Cretaceous. However, Saccocoma and Nautiloculina oolithica proved late Jurassic Age of its lower part (limestone). The Cretaceous Lumshiwal Formation is represented by mixed carbonatic-siliciclastic sediments in the Ali Sahib Well, indicating shallowing upward. Goethite in the clastic sediments of this formation (Amir Wali Well) indicates weathering under permanently humid conditions in the provenance area. Deeper marine depositional environment is suggested for the (?) Paleocene Ranikot Formation. Source rock characterization was carried out by organic geochemistry, including biomarkers. Organic matter is mostly represented by Type-III kerogen, immature to marginal mature. The Chichali Formation (kerogen of algal/microbial origin) and the Datta Formation (mixed algal/bacterial and land plant origin) show in few samples relatively fair generative potential for hydrocarbons. For the Cretaceous Lumshiwal Formation and the Jurassic Samana Suk Formation, a kerogen origin is suggested as for the Datta Formation (s. above). During Cretaceous age (the Chichali Formation and the Lumshiwal Formation), the depositional environment was anoxic/reducing marine. The present data indicate an oxic to dysoxic depositional environment of the Jurassic Datta Formation and Samana Suk Formation.
    Translated title of the contributionSedimentologie und organische Geochemie an potentiellen Mutter- und Speichergesteinen im Zentralen Punjab, Teil des Indus Beckens
    Original languageEnglish
    QualificationDr.mont.
    Supervisors/Advisors
    • Vortisch, Walter, Assessor A (internal)
    • Schmid, Christian, Assessor B (internal)
    Publication statusPublished - 2010

    Bibliographical note

    embargoed until 08-03-2015

    Keywords

    • Punjab Basin
    • Ranikot Formation Lumshiwal Formation Chichali Formation Samana Suk Formation Datta Formation Sedimentology Biostratigraphy Organic Geochemistry Hydrocarbon potential

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