The Wolfspar® Field Trial: Testing a new paradigm for low-frequency 3-D velocity surveys

To realize the vision of automatic velocity model building with full-waveform inversion, a paradigm shift in the way seismic data are acquired is necessary. In December 2017 – January 2018 BP acquired 1000km of source lines over the deepwater sub-salt Mad Dog field in the US Gulf of Mexico using our prototype low-frequency source (LFS), Wolfspar. This was the first industry test of a new acquisition paradigm: a 3-D marine survey designed primarily for velocity-model building in areas of complex geology, using a source specifically designed for that task. It was a simultaneous-source survey, with two airguns and the LFS being recorded by the same ocean-bottom nodes. The Field Trial demonstrated that the source could operate for the required length of time for a 3-D survey, operate simultaneously with airguns without interfering with the airgun data or impacting operations, record low-frequency data at offsets wider than has been possible with airguns, and the resulting data could successfully be used for Full-Waveform Inversion to create an improved velocity model. We believe that the future of seismic acquisition in areas with complex geology will require bespoke surveys for velocity model building, and this experiment was a necessary first step.