Appraisal of reservoir quality for hydrocarbon-bearing deep-water Miocene sandstones incised valley, south-east Asian offshore Indus: An application of seismic attributes and instantaneous spectral porosity quantitative reservoir simulations

Muhammad Tayyab Naseer; Abha Singh; Raja Hammad Khalid; Shazia Naseem; Ilyas Khan; George Kontakiotis

doi:10.1016/j.heliyon.2024.e29554

Appraisal of reservoir quality for hydrocarbon-bearing deep-water Miocene sandstones incised valley, south-east Asian offshore Indus: An application of seismic attributes and instantaneous spectral porosity quantitative reservoir simulations

Heliyon. 2024 Apr 16;10(9):e29554. doi: 10.1016/j.heliyon.2024.e29554. eCollection 2024 May 15.

Authors

Muhammad Tayyab Naseer^{1

2

3}, Abha Singh⁴, Raja Hammad Khalid², Shazia Naseem², Ilyas Khan⁵, George Kontakiotis⁶

Affiliations

¹ Exploration Department, MOL Pakistan Oil and Gas Co. B.V., Pakistan.
² Department of Earth Sciences, Quaid-I-Azam University, Islamabad, Pakistan.
³ Solid Earth Geophysics Division (SEGD), Center for Earth Quakes (CES) National Center for Physics (NCP), Quaid-I-Azam University Campus, Islamabad, Pakistan.
⁴ Department of Basic Sciences, College of Sciences and Theoretical Studies, Dammam-branch, Saudi Electronic University, Riyadh, Saudi Arabia.
⁵ Department of Mathematics, College of Science Al-Zulfi, Majmaah University, Al-Majmaah, 1952, Saudi Arabia.
⁶ Department of Historical Geology-Paleontology, Faculty of Geology and Geoenvironment, School of Earth Sciences, National and Kapodistrian University of Athens, Panepistimiopolis, Zografou, 15784, Athens, Greece.

Abstract

Incised marine valleys (IVS) are hot topics in exploring the stratigraphic oil and gas-bearing plays. Multiple channelized sandstone lenses at varying depths [m], thicknesses [m], and porosities [%] constrain seismic impedance. The presence of hydrocarbon-bearing resources affects the seismic impedance (density (g/cc) and velocity (m/s)). Therefore, a quantitative prediction has been carried out for determining the thickness [m], porosity [%], and depths [m] of laterally distributed channelized sandstone lenses (SLS) for IVS, Indus offshore Basin (IOB), Pakistan, using 2-D instantaneous spectral porosity quantitative modelling (2DSSM), continuous wavelet transforms-based (CWT) 2-D instantaneous spectral density modelling (2DSSDM), and spectral decomposition tools. The 2DSSM remained limited in predicting the number of channelized sandstone lenses and their quantitative stratigraphic attributes. The 45-Hz-based processing of conventional 2DSSM has resolved the two channelized sandstone lenses of the stratigraphic trap. The deepest channelized sandstone lens has attained 1-6 m thickness with a lateral extent of 3 km, within the porosity range of 18-33 %. The highest confidence level for predicted petrophysical attributes such as 13 m-thick pay zones, -0.08, -0.067, and -0.07 acoustic impedances [g/c.c.*m/s], and 28 % porosities with R² > 0.85 have validated interpretations. The response of 45-Hz CWT waveform-based inverted density and thickness simulations has predicted the highest thicknesses and lowest densities of reservoir sandstones within the meandering channel belt of the deepwater depositional system. The predicted densities and thicknesses for the coarse-grained sandstone lenses of point bars were 1.8-1.9 g/cc and 15 m, respectively. In the same way, the quantitative estimates of predicted density and simulated thickness have shown a strong coefficient correlation (R² > 0.80), which confirms the presence of gas-bearing prospects within the IVS. The facies-controlled migration is thought to be the movement of the reservoir facies of the point bars and channelled sandstone-filled lenses to the side.

Keywords: 45-Hz-based processing; Coarse-grained sandstone deposits; Conventional seismic data; Deep-water depositional sequences.