Tectonostratigraphic framework of early-Cretaceous hydrocarbon-bearing deep-water architectures, divergent plate margins, NE-Arabian Sea: Spectral decomposition-based density-thickness-constraint lateral variability static reservoir simulations

Abstract

Lowstands prograding wedges (LPWs) and basin floor fans (BFF) are the hottest areas for stratigraphic-based consortiums of hydrocarbon explorations. These stratigraphic traps are developed during the extensive fall of the sea, and subsequent, very slow rise inside the Lowstands system tract (LST). Hence, they mark the paleo-shelf-break and structure closure along the deep-water depositional systems (DWS). However, Pakistan exists on the verge of diverging plate boundaries, which have signified traverses of Horst and Grabens geological structures along normal faults. NW-SE aligned wrench faults, local-to-regional scale transverse fractures, and together with intensely fluctuating NE-Arabian rising sea levels have collectively constrained the development of tectonostratigraphic architecture throughout slope-to-basin floor patterns. Subsequently, the full spectrum seismic amplitude-based volumes (FSM) generate ambiguities in the quantitative prediction of DWS. This research utilizes the broadband prompt spectrum waveform-originated thickness and density-controlled inverted velocities and density basin simulations (TDVDRS) of the Cretaceous system, NE-Arabian Sea. However, these FSM attributes failed to image the laterally continuous and possible gas-bearing sediments due to a poorly resolved thickness of 6 m. This thickness was below the tuning thickness threshold of 14 m for this source-hydrocarbon play. The TDVDRS have predicted 15 m thick aggradational parasequences of the top seal, 13 m thick progradational-to-retrogradational lateral seal, and 12 m thick progradational shale of bottom sealing configurations. An angular unconformity was resolved at the top of Horst and Grabens structure at depths of 3240–3270 m and pseudo-thickening [PT] [m]: pseudo-density [gm. /c.c.] [PD] of 11–23-m: ∼2.05–2.25 gm. /c.c during falling sea-level. This process has replaced the younger erosional sediments at the compacted bottom and adjacent seal configurations. This workflow has strong tectonostratigraphic implications for diverging the NE-Arabian Sea, which may serve as an analogue for developing the world’s gigantic divergent plate margins.