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[Display omitted] • The 47-Hz TPRS resolves wet gas-bearing and light oil-bearing intervals (LOI). • The 47-Hz map images a 154 km2 NEE-SWW oriented stratigraphic play. • The 47-Hz TPRS images phase reversals and seismic-doublets at 170 to 200°F and porosity of 22 to 32 % WGI. • The used workflow has strong stratigraphic implications for field development strategies. Basin floor fans (BFF) of deltaic depositional systems are important stratigraphic traps, which are sourced by the regionally developed meandering channel belts and associated deposits of point bar facies. The vertical and lateral changes in the tectonics and sea level adversely affect the temperature (θ) and porosity constraints of petroleum plays within BFF of the lowstand system tracts. These fluctuations impact the sedimentary controls on thickness, lithology-impedance contrast, phase, and frequency of BFF. As a result of the reliance on full-spectrum seismics, quantifying thin-bedded stratigraphic wet gas-bearing intervals (WGI) and light oil-bearing intervals of petroleum systems becomes extremely difficult. This study utilizes seismic attributes and instantaneous spectral analysis-based temperature-porosity reservoir simulations (TPRS) to quantify the BFF of the Early-Cretaceous delta of the Miano gas field, Central Pakistan. The 47-Hz peak-tuned frequency component of spectral decomposition [SpecDecomp] images a 154 km2 NEE-SWW traversed and regionally developed stratigraphic prospect. Linear regression of R2 > 0.80 between spectral decomposition-based tuning frequency of 47-Hz and gross reservoir thickness of BFF validates the presence of gas-bearing shales. The 47-Hz wavelet-based TPRS has resolved the phase reversals and seismic-doublet signatures for thin-bedded shale PETROS at θ of 170°F to 200°F and porosities of 22 % to 32 % of WGI within BFF. TPRS at 47-Hz SpecDecomp profile between the frequency bandwidth spectrums of 12–62-Hz has reappraised the exact morphology of the continental shelf, shelf-slope, and BFF. A 21 m thick aggradational parasequence of BFF was deposited at an angle of 2° during the onset of subsidence and rapid fall, followed by a subsequent standstill of sea-level at θ of 170 to 200°F, ∼26 to 35 % porosities, and laterally fractured subsidized regimes of WGI.. A 20 m thick retrogradational fluvial-dominated facies was deposited at an angle of 35° during a rising followed by a standstill of sea level at a θ of 140 to 165°F, ∼08 % to 18 % porosity, and poorly fractured uplifted compressional regimes of light oil-bearing intervals. The aggradational WGI of Lowstand System Tracts was completely embedded by retrogradational shales of transgressed system tracts from the top of the aggradational and laterally. The uncertainty analysis has prevailed with a moderate-to-good R2 > 0.75 for BFF and a very poor R2 < 0.1 for fluvial-dominated point bar traps. Our workflow has implications in terms of exploring the tectonics and stratigraphic frameworks within the petroleum systems for imaging the most productive zones in a single snapshot of 47-Hz tuning frequency. [ABSTRACT FROM AUTHOR]

Prograding sandstone-filled incised valleys of the Lowstand System tract (LST) form stratigraphic plays. The band-limited seismic data interpretation techniques constrain the prediction of porous and gas-bearing reservoir facies. Therefore, the development of a cost-economic petroleum-bearing reservoir system is a challenge for reservoir geophysicists. This research is intended to predict the porosity and thickness of incised valleys by executing the continuous wavelet transforms (CWT)-based spectrum decomposition (SD), seismic static inverted simulation (SWM), and inverted seismic-based porosity simulation (IVPS) on a Lower Cretaceous LST system of Pakistan. The seismic, root-mean-square (RMS), and absolute average seismic attributes have provided a limited capability to image the gas-bearing sandstones. The 24-Hz tuning frequency has imaged the progradational sandstone-filled incised valley and retrogradational fluvial point bars. The 37-Hz has imaged the aggradational barrier bars. The amalgamation of multiple attributes has accurately demarcated the reservoir sandstone and sealing shale. The SWS has resolved a 32-m-thick prograding incised valley, 30-m-thick aggrading barrier bars, and 23-m-thick retrograding point bars within the complete fluvial hierarchy. The well correlation has provided evidence for the distribution of point bars, barrier bars, and shallow-marine incised valley reservoir facies. The 24-Hz CWT waveform-based conventional IVPS has predicted 94 and 42 m-thick valleys and "point bars" between 25 and 13% pseudo-porosity wells. The 24-Hz waveforms-based treatment of conventional IVPS has predicted enhanced thicknesses of 75 and 29 m for valley and point bar deposits with porosities between 25 and 13%. The 24-Hz IVPS has resolved two valleys compared to the conventional IVPS during the rapid fall of sea level and negligible rise, which have accumulated the coarse-grained point bar deposits of a fluvial meandering stream. The integration of IVPS and GR (API) has provided strong implications for the exploration of a pure stratigraphic trap within a shallow marine sedimentary system of Pakistan. A NE to SW oriented regional change was observed in the lithology, thickness, and depositional environments of the petroleum system. The dominant lithology in the eastern zones was point bar sandstones. The dominant lithology in the central zones was barrier bar sandstones. The dominant lithology in the western zone was incised valley sandstone. The thickness of the reservoir was 18 m thick in the west, which was reduced to 8 m in the eastern flanks of this gas field. The depositional environment in the northeast was fluvial, which changed to shallow-marine in the southwestern zones of the Indus basin. These lateral fluctuations have proved that a pure stratigraphic fairway was present within the LST of the Indus Basin of the sedimentary system of Pakistan. The porous incised valley stratigraphic reservoirs are embedded inside the non-porous shales, which validates the presence of a pure stratigraphic petroleum play inside the Indus Basin, Pakistan. [Display omitted] • The 24-Hz images of the sandstone-filled incised valley and fluvial point bars. • The SWS has resolved the thicknesses of an incised valley at 32 m, barrier bars at 30 m and the point bars at 23 m. • The 24-Hz processing of conventional IVPS predicts enhanced thickness 75 and 29 m at 25 and 13% porosity. [ABSTRACT FROM AUTHOR]

[Display omitted] • Constructed workflow is a vital case for discovery of gas-bearing fluvial stratigraphic traps. • The SRSN resolves the thin-bedded point bar sandstone deposits in the basin. • AI and thicknesses for point bars sandstone are −0.214 to −0.219 g/c.c.*m/s and 17 to 19 m. • SRSN image sedimentary facies during the sea-level rise and fall events. Fluvial depositional systems accommodate a variety of primary stratigraphic-based trapping pools (STP) such as the channelized sands (CS) and point bars (PB). When they are encased within the non-porous and compacted shales, they develop hydrocarbon-bearing reserves. However, these STP are developed during the rapidly rising sea level and standstill, which creates hurdles in the development of accommodation space to accumulate the thin-bedded (hydrocarbon-bearing) and coarse-grained PB. PB are the primary stratigraphic traps within the fluvial hierarchy. Therefore, they require sophisticated tools such as reflection-based impedance reservoir simulations to simulate the thickness, accommodation space, proximal and distal locations, and sealing configurations of PB from a 3D perspective. The conventional seismic amplitudes are not sufficient enough to quantitatively portray these seismic sedimentological attributes due to a lack of preserved amplitudes and tuning frequency content aimed at fluvial-dominated clastic sequences. Therefore, the ultimate goal of conducting this research work is to detect thin-beds of PB and CF aimed at accumulating and generating hydrocarbon-posture STP. These thin-bedded reservoir facies are very delicate in tuning the frequency of the sub-surface systems. They require amplitude-based seismic data interpretation tools such as amplitude-based seismic attributes and inverted reservoir simulations. These tools can image the exact thickness of the reservoir lithology and types of fluids compared to the bandlimited geometrical attributes. Generally, the inverted reservoir simulations reconstruct the reflection-based impedances for the stratigraphic reservoirs, which helps in the quantification of the sub-surface thin-bedded stratigraphic systems. Therefore, the amplitude-based seismic attributes and thin-bedded wedge static reservoir simulation (SRSN) tools are applied on the 3-D seismic data of a gas field of Indus Basin of Pakistan. The amalgamated root-mean-square (RMS)-based seismic amplitude and frequency highlighted a full of twist continuous meander channel with a sinuosity index (S.I) > 2.7. Strong low-frequency shadows are observed at 23 Hz magnitudes that authorize the restoration of petroleum-posture fluvial-dominated PB inside the STP. The amplitude attenuation model using the continuous wavelet transform (CWT) shows the rapid attenuation of spectral energy below the PB. The SRSN determined a 16 m thickness of STP using a constant velocity of 3449 m/s, which pinched out in the east of the Indus Basin. The predicted physical attributes from SRSN and their cross-plots against the thickness constraint have discriminated against the dominant sedimentary facies of the fluvial system during the significant rising and negligible falling sea levels followed by the standstill. The predicted physical parameters have enabled vigorous controls aimed at developing accommodating intervals that have stored a significant amount of hydrocarbon-bearing PB. The quantitative characterization has enhanced acoustic impedance [AI] [g/c.c.*m/s] and thickness of PB with a strong correlation coefficient of R2 > 0.93. The predicted AI [g/c.c.*m/s] and thicknesses [m] aimed at PB were −0.214 to −0.219 g/c.c.*m/s and 16 to 19 m. Therefore, the SRSN can be used as a dynamic instrument for the accurate prediction of AI [g/c.c.*m/s] and thickness for the characterization of fluvial systems. This workflow may serve as a vital example for exploring the oil and gas-bearing stratigraphic system within the Indus Basin and similar basin settings. [ABSTRACT FROM AUTHOR]

This study is aimed at imaging the deltaic depositional sequences in the Sukkur Rift Zone (SRZ) of the Lower Indus Basin, Pakistan. The seismic sequence, back stripping, and thin-bed wedge modeling tools were applied to the gas field of the SRZ to develop the foundations for tectonics and sedimentary processes in the distribution of potential hydrocarbon reservoirs. The conventional seismic method does not have the capability to predict the quantitative aspects of deltaic systems. Five passive seismic sequences were utilized for mapping the sediments of the foreland margin within the Indian Plate. The subsidence curves showed that the tectonic activity had occurred between the Lower Cretaceous and Eocene depositional sequences. The maximum tectonic activity was observed during 50–70 Ma within the SRZ. The upper shoreface depositional system was modeled by a thin-bed wedge model at enhanced thicknesses of 52 m, 55 m, 56 m, 57 m, 58 m, and 61 m. Thin-bed wedge modeling has provided solid evidence and implications for the development of stratigraphic traps within the upper shoreface depositional system. The thin bed wedge model remained an accurate tool for the prediction of direct hydrocarbon indicator (DHI) within the tectonically-influenced depositional systems. Hence, the presented research work can be used as an analogue for the development of tectonically and stratigraphically stable fairways within the Asian Basins and similar geological settings. [Display omitted] • Five seismic sequences were mapped within passive and foreland margin sediments of the Indian Plate. • Onlapping of Cretaceous sedimentary rocks onto the Jurassic rocks images regional unconformity. • Thin-bed wedge model expects 52 m, 55 m, 56 m, 57 m, 58 m and 61 m thick facies in upper shoreface system. • Thin-bed wedge model authenticated the tectonically diversified and fluctuating sea-level systems. [ABSTRACT FROM AUTHOR]