Reservoir attributes of a hydrocarbon-prone sandstone complex: case of the Pab Formation (Late Cretaceous) of Southwest Pakistan

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  • Muhammad Umar, Department of Earth Sciences, COMSATS Institute of Information Technology, University of Balochistan, Pakistan
  • Abdul Salam Khan, Centre of Excellence in Mineralogy, University of Balochstan, Quetta, Pakistan
  • Gilbert Kelling, School of Physical and Geographical Sciences, University of Keele, United Kingdom
  • Henrik Friis
  • Akhtar Muhammad Kassi, Department of Geology, University of Balochistan, Quetta, Pakistan
Links between the architectural elements of major sand bodies and reservoir attributes have been explored in a field study of the hydrocarbon-yielding Late Cretaceous Pab Formation of southwest Pakistan. The lithofacies and facies associations represented in the Pab Formation are the main determinants of its reservoir properties. Thus, thick, vertically connected and laterally continuous sand packets have moderate-to-high mean porosities (10–13 %) in fluviodeltaic, shoreface, shelf delta, submarine channel, and fan-lobe facies associations while deeper shelf and basin floor sand bodies yield significantly lower porosities (4–6 %). Overall, in the Pab arenites, porosity values increase with increasing grain size and better sorting. The varying sand-shale ratios encountered in different sectors of the Pab outcrop are also petrophysically important: Sequences displaying high ratios yield higher bulk porosity values than more shale-rich successions. Diagenetic studies of Pab sandstones reveal that intense mechanical compaction and cementation have reduced primary porosity and reservoir quality. Conversely, dissolution of detrital feldspar grains and volcanic fragments during burial and later uplift of these arenites has generated significant secondary porosity.
Original languageEnglish
JournalArabian Journal of Geosciences
Pages (from-to)1-15
Publication statusPublished - Jan 2016

    Research areas

  • porosity , Sandstone, Facies associations, Diagenesis, Texture

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