Imaging of Stratigraphic Pinch-Out Traps Within the Lower-Cretaceous Shaly-Sandstone System, Pakistan, Using 3D Quantitative Seismic Inverted Porosity–Velocity Modeling

Incised valleys form excellent stratigraphic pinch-out traps. Traditional seismic data analysis techniques fail to predict quantitatively the porous and low-velocity sand-fills for incised valleys. The 3D quantitative seismic inverted porosity–velocity (3DQSIPV) analysis was applied in the Indus Basin, SW Pakistan. The reflection strength attribute better portrayed the reservoir sandstone and faults compared to seismic amplitude attribute. The sweetness-based continuous wavelet transform authenticated the development of the stratigraphic play. The 17 Hz amplitude delineated the non-porous seal and porous reservoirs of sand-filled incised valley and strand plain, and faults. The integrated model of seismic attributes categorizes the reservoir and seal constituents. The petrophysical modeling corroborated the gas-bearing “sweet-spots” within the stratigraphic-based dynamical system. The facies modeling predicted the for coarse-grained sandstone and fine-grained shales, depositional environments, fluctuations of sea level and their impacts on the overall development of stratigraphic plays. The predicted density and P-wave velocity for the sandstone-filled incised valley of the lowstand system tract were ~ 1.4–1.75 g/cc and ~ 3217–3802 m/s, respectively. The predicted density and P-wave velocity for the sealing shales facies of strand plain of transgressive system tract were ~ 1.9–2.1 g/cc and 2.55–2.7 g/cc and 3900–4700 m/s, respectively. The 3DQSIPV predicted > 25% porosity and ~ 3300 m/s velocity of reservoirs in the west. The eastern zones shows   0.90 for inverted velocity. This workflow may serve as an analogue for the remaining oil and gas fields of the Indus Basins of Pakistan and similar geological settings of divergent plate margins.