ORIGINAL PAPER Petrophysical parameters and modelling of the Eocene reservoirs in the Qadirpur area, Central Indus Basin, Pakistan: implications from well log analysis Miraj Khan 1 & Mohammad Arif 1,2 & Nowrad Ali 1 & Mohammad Yaseen 1 & Ammar Ahmed 3 & Syed Mamoon Siyar 4 Received: 17 January 2015 /Accepted: 8 February 2016 # Saudi Society for Geosciences 2016 Abstract The Eocene rock units of the Qadirpur field, Central Indus Basin (Pakistan), are investigated petrophysically for their detailed reservoir characterization. The different petrophysical parameters determined include the following: true resistivity, shale volume, total porosity, effective porosity, density and neu- tron porosity, water and hydrocarbon saturation, bulk volume of water, lithology, gas effect, P-wave velocity, movable hydrocar- bon index and irreducible water saturation and integrated with different cross-plots. The Eocene reservoirs are excellent with high effective porosity (2–32 %) and hydrocarbon saturation (10–93 %). Among these, the Sui Upper Limestone is an overall a poor reservoir; however, it has some hydrocarbon-rich intervals with high effective porosity and better net pay. All the net pay zones identified show low and variable shale volume (5–30 %). The secondary porosity has added to the total and effective po- rosities in these reservoirs. The main contributors to the porosity are the chalky, intercrystalline and vuggy/fracture types. The thickness of the reservoirs zones ranges from 4.5 to 62 m. These reservoirs are gas-producing carbonates with almost irre- ducible water saturation (0.002–0.01) and are likely to produce water-free hydrocarbons. The lower values of moveable hydro- carbon index (0.07–0.9) show that the hydrocarbons are move- able spontaneously to the well bore. The proposed correlation model shows that the reservoirs have an inclined geometry and are a part of an anticlinal trap. Keywords Qadirpur field . Gas-producing carbonates . Net pay zones Introduction The Qadirpur area falls in Central Indus Basin, which is bounded by the Indian Shield in the east, marginal zone of the Indian Plate in the west and Sukkar Rift in the south and is separated from the Upper Indus Basin by the Sargodha High and Pezu Uplift in the north (Kazmi and Jan 1997) Fig. 1). The Central Indus Basin is a major hydrocarbon-producing prov- ince of Pakistan. Here, the potential source rocks are shales of the Sembar Formation; however, shales of Mughalkot, Ranikot, Ghazij and Sirki Formations may also be considered. The Sui Main Limestone, which is exposed nowhere in Pakistan (Siddiqui 2004), and the Sui Upper Limestone are the main producers, whereas the Habib Rahi Limestone is believed to be a secondary reservoir (Ali et al. 2005). The Ghazij Shales act as a cap for the Sui Main and Sui Upper Limestones, while the Sirki Shales cap the Habib Rahi Limestone (Kadri 1995). There are some large, clearly detachment anticlines within the Kirthar and Sulaiman belts, especially along their eastern margins. The northward-striking eastern Sulaiman structural play domain has narrow, straight, tens of kilometre long anti- clines with limbs broken locally by steeply dipping faults with reverse dip separation. These structures are interpreted as flower structures produced by a large-scale distributive wrench faulting having prospective reservoirs, e.g. the Ranikot Formation (Paleocene), Pab Formation and Lower Goru Formation of Cretaceous age (Kemal et al. 1992). * Mohammad Arif arif_pkpk@yahoo.com 1 Department of Geology, University of Peshawar, Peshawar 25120, Pakistan 2 Department of Earth Sciences, CIIT, Abbottabad 22060, Pakistan 3 Schlumberger, DCS, Islamabad, Pakistan 4 Saif Energy, Islamabad, Pakistan Arab J Geosci (2016) 9:425 DOI 10.1007/s12517-016-2373-2