Abstract

In 2010, the world's largest optical permanent reservoir monitoring (PRM) system was installed in the southern part of the Norwegian North Sea at Ekofisk. The life-of-field seismic (LoFS) system consists of 3966 seabed multicomponent sensors along 200 km of mostly trenched fiber-optic seismic cables and covering about 60 km2 of Ekofisk field. Seismic data are acquired via a topside recording unit and a containerized source operated on a supply vessel. Six vintages of data were acquired between the end of 2010 and fall 2013. Different aspects of seismic operations at Ekofisk include seismic source, recording system, data transfer, quality control, and processing. One of the key factors in achieving the full value of a PRM system is to handle such operations in a safe, integrated, and efficient manner to deliver high-quality seismic volumes for interpretation with rapid turnaround. Key aspects of the 4D processing sequence include robustness and optimal turnaround. Integration of the different operational phases of the LoFS project and integration of expertise between client and contractor play a key role in delivering clean, well-resolvable 4D signals and low residual 4D noise with NRMS as low as 5%. The high-quality data delivered by operations and processing are now routinely used in well planning and reservoir-management workflows.

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