Publications

Sisi-Nubi gas field is operated by Total E&P Indonésie within the Mahakam PSC. Both Sisi and Nubi sub-fields represent similar contiguous structures consisting of several N30 tilted panels. The pay zone is located in the Upper Miocene interval and represents a sequence of sand channels and bars among the shale layers crossed by intensive faulting.The main geophysical challenges not overcome by former 2005 time processing, are related to a complex geological setting (carbonate reefs, shallow gas channels, faulting etc.), provoking:- Static push-down/pull-up distortions,- Seismic signal attenuation, low signal-to-noise ratio,- Multiples in shallow-water conditions,- Imaging distortions under the faults (faultshadowing or/and fault-mode).For the above reasons, a Pre-Stack Depth Migration reprocessing was performed in 2010 in CGGVeritas Jakarta centre.Processing of the seismic data for future structural interpretation and seismic reservoir characterization often faces certain mutually exclusive requirements including the demand for the exhaustive suppression of all the noise and multiple energy together with the preservation of primary seismic energy, migration parameterization with the aim of the best imaging of dipping events and the necessity to avoid the undesirable migration operator artifacts, etc.The strategy included a full preprocessing followed by the application of two anisotropic PSDM algorithms: Controlled Beam (CB-PSDM) and Kirchhoff (K-PSDM) anticipated by a multiiteration update of a velocity model. Three datasets of various acquisitions with different azimuths were exploited to improve the efficiency of tomographic velocity inversion and to check the velocity anisotropy.The key steps of the pre-processing were followed by a monitoring of the evolution of seismic indicators showing the enhancement of data quality using proprietary seismic software “Sismage.