Imaging The Pre-khuff: Changing The Game With Innovative Seismic Technology

This paper describes how QSUI was able to overcome some of the significant geophysical challenges associated with Pre-Khuff exploration. On legacy seismic data, strong multiples from the layered carbonate overburden overwhelm the relatively weak primary reflections from the deep Pre-Khuff clastics. In order to identify and understand the main generators of coherent seismic noise, Qatar Shell Upstream International (QSUI) has undertaken seismic modeling using VSP data, legacy shot records and full-waveform synthetic modeling. Results of this work informed the reprocessing of existing seismic and the design of a 3D Ocean Bottom Cable (OBC) seismic survey. The acquisition of dual component (2C) Wide-Azimuth (WAZ) OBC data, together with state-of-the art in-house seismic processing led to a break-through in seimsic imaging of the Pre-Khuff reservoir layers. This has demonstrated that the geologic intervals below the Hercynian unconformity exhibit a steeper dip compared to the overlying Khuff and younger sediments, as expected by the geologists and observed in neighboring countries.