| Popis: |
Summary In facing the challenge of imaging complex three-dimensional structures with high impedance contrast boundaries, geophysical theory tells us that we need data with long offsets, rich azimuthal content and as high as bandwidth as possible. In particular, the importance of the information carried by low frequencies has been highlighted as critical in such diverse geological situations as sub-basalt imaging and GOM sub-salt imaging. While modern ocean-bottom nodal based acquisition has made the acquisition of long offsets and rich azimuths operationally and economically feasible, it is still common for OBS exploration surveys to be carried out with sources and receivers that are not optimised for low-frequency data acquisition. In this paper, we report on a survey we recently carried out in the Western Gulf of Mexico using a source that was optimised to provide an uplift in signal to noise at low frequencies. This source may be characterised as a pneumatic seismic source as it is based on airgun technology. The new source, while designed to optimise the signal to noise ratio at frequencies less than 4 Hz, also provides significant signal across the full seismic bandwidth typically used in modern imaging projects. |
