Porosity prediction of lower cretaceous unconventional resource play, south Indus Basin, Pakistan, using the seismic spe

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ORIGINAL PAPER

Porosity prediction of lower cretaceous unconventional resource play, south Indus Basin, Pakistan, the using seismic spectral decomposition technique Muhammad Tayyab Naseer 1 & Shazia Asim 1,2 Received: 14 December 2017 / Accepted: 26 April 2018 # Saudi Society for Geosciences 2018

Abstract Incised-valley shale systems are renowned as the fruitful exploration domains. However, the stratigraphic heterogeneity is significant, and thus, identifying the porous compartments within the thin-bedded and fractured shale system is one of the unconventional stratigraphic challenges. We present an innovative scheme for the exploration of the porous unconventional resources within the south Indus basin, Pakistan. The continuous wavelet transforms (CWT) exclusively detects the porous shales within the complete fractured system as compared to the full spectrum seismic data interpretation tool. The seismic amplitude, instantaneous frequency, and reflection strength tools show some tuning effects due to lithology and fluids. However, the tuning block of 28 Hz envelope sub-bands in conjunction with instantaneous phase tool accurately mark out the shale-plugged pinch out reservoirs. The synthetic wedge model based on the conventional seismic wavelet resolves the shale bed (incised-valley shalefilled lens) of about 23 m thickness, but shows limited imaging capability due to frequency band limitation for the porous shale locale. The acoustic impedance based on instantaneous spectral porosity modeling using the tuning volume of 28 Hz CWT has spectacularly resolved the thin-beds (gas shows) within the porosity range of 20 to 30%, which may have implications for future exploration of unconventional stratigraphic plays. Keywords Continuous wavelet transforms . Incised valley . Resource shale play . Seismic attributes . Static reservoir modeling . Porosity prediction

Introduction Unconventional oil or gas resources remain much more demanding towards extract as associated to the conventional ones. Some of these resources stand trapped in reservoirs with poor permeability and porosity, meaning This work has been conducted within the 3D seismic geophysical reservoir characterization Lab, Department of Earth Sciences, Quaid-IAzam University, Islamabad, Pakistan. * Muhammad Tayyab Naseer [email protected]; [email protected] Shazia Asim [email protected] 1

3D Seismic Geophysical Reservoir Characterizations Lab, Department of Earth Sciences, Quaid-I-Azam University, Islamabad, Pakistan

2

Institute of Geomatics and Geophysics, China University of Geosciences, Wuhan, Hubei, China

that it is extremely difficult or impossible for oil or natural gas to flow through the pores and into a standard well. To be able to produce from these difficult reservoirs, specialized techniques and tools are used. For example, the removal of shale oil, tight gas, and shale gasmust comprises a hydraulic fracturing phase in order to generate cracks for the oil or gas to flow through Boyle et al. (2012). The challenge is confront