--> Abstract: Benefits of Dual-Sensor Acquisition for Arctic Marine Seismic, by S. Pharez and A. Dementjev; #90096 (2009)

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Benefits of Dual-Sensor Acquisition for Arctic Marine Seismic

Stephen Pharez1 and Alexander Dementjev2
1PGS, Weybridge, United Kingdom.
2PGS, Moscow, Russia.

The quest for the remaining oil and gas fields is getting harder. Reservoirs are deeper, covered with complex overburden and within increasingly complex stratigraphic traps. To meet this need, seismic exploration requires extended bandwidth: More low frequencies for better penetration (in areas such as sub-salt and sub-basalt) and more high frequencies for increased resolution.

Unfortunately, the bandwidth in marine seismic is constrained by the recording sensor depth and a compromise is usually reached between the frequency range required at the target level and the depth of tow. (A shallow streamer is favorable to high frequencies and detrimental to low frequencies. Conversely, a deeper streamer favors low frequencies at the expense of high frequencies.)

In the Arctic there are also operational benefits to be gained from a deeper tow, however the frequency content can be limiting on shallow resolution. Conventional streamers use hydrophones to measure changes in pressure, however, a new dual-sensor streamer design utilizes two types of sensor; pressure and velocity, the combination of which allows the full data bandwidth to be restored. Thus a deeper tow is now practical and indeed desirable, with no trade-off between high and low frequencies. This in turn benefits both penetration and resolution of seismic reflections, to provide a clearer image of the subsurface.

2D and 3D data have now been acquired around the globe using this new technology. In all cases, results from these surveys confirm the expected benefits, namely better penetration, enhanced resolution and improved imaging and attributes. Comparisons are shown between conventional seismic streamer data and dual-sensor streamer data. The processing sequence is standard and the same for both datasets following the dual-sensor summation. The dual-sensor data exhibits higher S/N ratio in general and higher continuity and resolution. The structural interpretation could change due to the improved data quality and imaging.

The benefits from the opportunity to tow deep (15-25m) have positive operational implications; the weather window can be extended as the streamer is below the wave zone and thus less affected by weather related noise.

Thus we see that both data quality and operational improvements result from the use of dual-sensor streamer technology.


AAPG Search and Discover Article #90096©2009 AAPG 3-P Arctic Conference and Exhibition, Moscow, Russia