Higher Vibrator Hydraulic Force for Improved High Frequency Generation

Tellier, Nicolas; Ollivrin, Gilles; Caradec, G.

doi:10.3997/2214-4609.201412605

Cited by 5 publications

(2 citation statements)

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“…As a result, the emitted Ground Force (GF) drops. A solution (Tellier Ollivrin and Caradec ) is to generate at high frequency a hydraulic peak force bigger than the hold‐down (that is about the weight of the vibrator). This enables the increase of the reaction‐mass acceleration and, thus, its contribution to the GF at high frequency (GF is still less than the vibrator weight due to the subtractive interference of the baseplate).…”

Section: Land Equipment For Broadband Seismic: the Source Sidementioning

confidence: 99%

Marine, seabed, and land seismic equipment for broadband acquisition: a review

Mougenot¹

2017

Geophysical Prospecting

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The broadband capabilities of marine, seabed, and land seismic equipment are reviewed with respect to both the source and the receiver sides. In marine acquisition, the main issue at both ends of the spectrum relates to ghosts occurring at the sea surface. Broadband deghosting requires towing at variable depth to introduce notch diversity or using new equipment like multi‐component and/or low‐noise streamers. As a result, a doubling of the bandwidth from about three to six octaves (2.5–200 Hz) has been achieved. Such improvement is not yet observed for seabed surveys in spite of deghosting being a standard process on the receiver side. One issue may be related to the coupling of the particle motion sensor, particularly at high frequencies. For land acquisition, progress came from the vibrators. New shakers and control electronics using broadband sweeps made it possible to add two more octaves to the low‐frequency signal (from 8 to 2 Hz). Whereas conventional 10 Hz geophones are still able to record such low frequencies, 5 Hz high gain geophones or digital accelerometers enhance them to keep the signal above the noise floor. On the high end of the bandwidth, progress is not limited by equipment specifications. Here, the issue is related to a low signal‐to‐noise ratio due to the strong absorption that occurs during signal propagation. To succeed in enlarging the bandwidth, these improved equipment and sweeps must be complemented by a denser spatial sampling of the wavefield by point–source and point–receiver acquisition.

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Section: Land Equipment For Broadband Seismic: the Source Sidementioning

confidence: 99%

Marine, seabed, and land seismic equipment for broadband acquisition: a review

Mougenot¹

2017

Geophysical Prospecting

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“…A proper combination of accelerometers can provide a QC much closer to the reality, and thus improve the generated signal fidelity. A hydraulic peak force exceeding the vibrator hold-down weight provides additional hydraulic margin to compensate for the mass to baseplate increasing phase shift and enables the efficient generation of an extra bandwidth (Tellier 2015). Lastly, as for lowfrequency, stable and well-controlled hydraulic pressures prevent reaching the maximum available pressure.…”

Section: Improvementsmentioning

confidence: 99%

Vibrator Evolutions for Broadband Performance: Accomplishments and Remaining Issues

Tellier¹

2015

Proceedings

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SUMMARYExtending the frequencies available for seismic imaging has been a key priority for the industry in recent years, so extra octaves of signal have to be generated. However, the design of vibrators implies limitations that differ with frequency. After a review of the main vibrator limitations at low and high frequencies, the proposed abstract presents the main improvements achieved up until now, and the limitations that are still pending.

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