Today, Güralp Systems announced the successful deployment of an array of ocean-bottom nodes as part of a 3D active marine seismic survey off the coast of Australia. The nodes have extended the aperture of the streamer survey from eight to thirty kilometres.
Güralp, in conjunction with their Australian representatives at the Seismology Research Centre, have recently supplied an array of twenty ocean-bottom seismic nodes to the Australian Geophysical Observing System (AGOS). Following a test in shallow water, the nodes were deployed for one week over an oil field on the North West Australian margin in a water depth of 1100 metres, within the area of a 3D marine seismic survey. Seismic signals from the survey were recorded to offsets in excess of thirty kilometres and could have been recorded to even larger offsets, had the acquisition geometry allowed larger separations between sources and receivers.
Alexey Goncharov at Geoscience Australia commented, “This is a major extension of the recording aperture compared to eight-kilometre long streamers used on that survey”. The large offset data obtained can be used for:
- Deep penetrating velocity estimates from travel-time tomography
- Full wave-form inversion
- 2D wide-angle reflection seismic imaging
- Improved NMO-based velocity analyses
- Broadband imaging by recording low frequency spectrum (2 Hz to 8 Hz)
- Analysis of converted seismic waves, anisotropy and estimates of rocks fluid saturation from 3-component data
The Güralp nodes acquire three-component broadband seismic data from 0.03 Hertz to 100 Hertz and can operate for up to twelve months in water depths up to 6000 metres. The nodes were easily deployed using the 21 metre vessel Capricorn Lady, equipped with an A-frame at the stern. The nodes sink to the ocean floor and start recording automatically. Their deployed location is determined using an acoustic positioning system. On completion of the survey, the nodes are commanded to return to the surface using an acoustic communication link on the vessel. Once at the surface, the nodes broadcast their position over radio to facilitate recovery.
Mark Volanthen, Managing Director of Güralp Oil & Gas, stated “I am delighted that AGOS chose to work with Güralp on this project. This is the first time Güralp nodes have been used to provide additional data to streamer surveys. Our nodes are more frequently used for applications including surveillance of underground gas storage facilities, monitoring natural fractures in the overburden around oil and gas fields and life-of-field monitoring of oil and gas reservoirs to maximise hydrocarbon recovery”. Güralp sells and rents arrays of ocean-bottom seismometers for both permanent, real-time, cabled installations and temporary, free-fall or ROV-installed applications.
A video clip of the shallow water test deployment and recovery can be seen below:
For further information about Güralp, contact firstname.lastname@example.org.