Reservoir characterization for Lower-Cretaceous fluid system in Southwest Pakistan based on seismic spectrum decomposition and static wedge modelling

• Published in: Energy reports 2021-11, Vol.7, p.1306-1325
• Main Authors: Naseer, Muhammad Tayyab, Asim, Shazia, Shah, Muhammad Ali, Awais, Muhammad
• Format: Article
• Language: English
• Subjects: Continuous wavelet transform (CWT)-spectrum decomposition (SD); Fluvial-dominated channel sands; Static wedge modelling (SWM); Stratigraphic reservoir characterization; Thick and thin beds
• ISSN: 2352-4847; 2352-4847
• DOI: 10.1016/j.egyr.2021.02.047

This is an innovative study that deals with the application of continuous wavelet transform (CWT)-based seismic spectrum decomposition (SD) and static wedge modelling (SWM) to characterize the fluvial system of Indus Basin, Pakistan. The CWT better discriminates the thin and thick-bedded hydrocarbon-bearing reservoir pore-fluids compared to band-limited seismic characteristics. The hydrocarbon-bearing point bar shows higher amplitudes compared to the water-filled channel, which indicates lower amplitudes A static amalgamation of CWT attributes within the sandstone reservoirs indicates that 28 Hz can resolve the thick-bedded sandstone-filled point bar facies. The mapping of reservoir facies within the 27 Hz to 40 Hz CWT-based frequencies predicts the lateral distribution of channel sandstone, fluvial point bars, regional faults, and three-dimensional seal of shale-bearing levee deposits. The 48 Hz amplitudes can be used for predicting the regional seal for petroleum system. The SWM resolves a 25 m thick gas-bearing fluvial point bar, which is laterally distributed by head-to-head continuity of 29 km. The SWM can be used to predict the quantitative aspects of fluvial systems. The paleo-flow direction of the river was predicted in NNE-SSW orientations. The low-velocity of ∼3500 m/s of river flow eroded the coarse-grained sandstone facies from the eastern flanks and deposited in the western regions of the Basin. The angle of stratigraphic trap and thickness of point bar petroleum system was 20° and 25 m in the west of Basin. These observations can serve as an analogue for the development of stratigraphic plays within the Indus Basins of Pakistan and fluvial systems with similar geological settings. [Display omitted] •The hydrocarbon-bearing point bar demonstrates high-amplitudes (∼2833 dB).•The water-filled channel indicates low-amplitudes (∼1601 dB).•28 Hz spectral magnitudes resolve the thick sand-filled point bar facies.•48 Hz found beneficial for providing the regional seal for the petroleum system.•Static wedge modelling (SWM) settles a 25 m thick fluvial point bar with lateral extent of 29 km.