Infield Seafloor Geometry Solutions Using a Hybrid Acoustic Pinger and First Break Analysis

D.A. Lamb, J.G. Starr, C. Diggins, E. Marc
2002 64th EAGE Conference & Exhibition   unpublished
Seafloor receiver positioning has traditionally been carried out with high frequency acoustic pinger observations and GPS data. This positioning accuracy can be then confirmed by displays of Linear Move Out (LMO) corrected seismic data in the shot and seafloor station domains. Shot and seafloor stations with correct positions appear flattened in these displays; those with position errors deviate from being flat. However, there are a number of problems with this method. It can be impractical for
more » ... be impractical for large volumes of data. Also, it is assumed that the linear moveout is generated by direct arrivals through the water layer. In shallow water, the acoustic energy may not be transmitted through the water column; instead it may travel beneath the water bottom as a refractor. In addition, the seafloor cable may move or be pulled after the pinger solution has been generated, making the initial solution invalid. We have demonstrated that, provided there is a good statistical distribution of measurements, first break analysis can provide accurate positions. First break positions can be comparable to those of high frequency acoustic pingers, using offsets much greater than previously thought possible. This method can highlight issues described above. We propose a hybrid solution that combines the pinger/GPS solution with a refraction-based geometry analysis of the seafloor seismic data. Finally, we confirm the results of these processes by cross-correlating directional stacks of binned traces.
doi:10.3997/2214-4609-pdb.5.p156 fatcat:jzdqbmm3jbavhbmhbvdmnlfzwi