ACQUISITION - MARINE

Solid StreamersSeal Sentinel® Solid Streamers

Safer, Quieter, Better

Seal Sentinel® Solid Streamers

The CGGVeritas marine seismic fleet has the largest deployment of Seal Sentinel Solid Streamers in the industry. These streamers are recognised for their low-noise properties and low-frequency recording capabilities, providing better signal penetration and benefiting sub-salt, sub-basalt and deep targets. Sentinel is the quietest marine streamer available today, with a design that reduces noise and drag. Sentinel is the streamer of choice for consistency, reliability, high signal-to-noise and broadband recording.

FEATURES:

•Designed to record high-quality seismic with a 2-3 Hz low-frequency response:

- Quiet low drag design

- Uniform density facilitates depth control

- Increased depth stability in variable water temperatures and salinity

•Improved reliability by design:

- Distributed waterproof electronics

- Redundant data transmission and power systems

•Compatible with Nautilus® integrated 3-in-1 steering, depth control and acoustic device

•Robust design allows ultra-deep tow (up to 50m)

•When used in BroadSeis™ variable-depth mode, can record six octaves of data (2.4 – 155Hz)

BENEFITS:

Safer:

•Solid body is environmentally friendly

•Proven in sensitive frontier areas, including the Arctic

•Stronger and less susceptible to in-sea damage

Quieter:

•Solid design reduces noise sensitivity and improves signal-to-noise ratio

•Hydrophone decoupled from stress member to minimize vibration noise sensitivity

•Consistent low-noise performance for better 4D sensitivity

Better:

•High-fidelity low-frequency recording

•Deeper penetration for imaging beneath complex overburdens

•Wider bandwidth for seismic inversion

•Uniform density improves depth stability and 4D reliability

•Noise resistance allows recording in a wider weather window

•Improved reliability-by-design leads to less technical downtime, leading to greater efficiency

Environmentally friendly solid streamers contain no fluids and are resistant to in-sea damage.

The CGGVeritas fleet has the most extensive deployment of solid streamers in the industry.

cggveritas.com

ACQUISITION - MARINE

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LOW NOISE

Sentinel is specifically designed to reduce noise and is the only truly solid streamer. It is constructed from extruded polymer foam, which replaces the fluid or gel present in other streamers and inhibits the transmission of noise wave modes, such as bulge waves, that propagate along the fluid in the cable.

Uniquely in Sentinel, the hydrophone is cylindrical and flexible and the sensing elements are isolated from the central strain member to minimize vibration noise sensitivity. In typical fluid and gel streamers the hydrophone is coupled to the strain members and is therefore subject to vibration noise.

This makes Sentinel inherently quieter than either fluid or gel cables, as shown below. In addition, solid streamers have uniform density and stable buoyancy and so provide better depth stability.

BENEFITS OF LOW-FREQUENCY RECORDING

The lower noise floor of solid streamers provides a better signal-to-noise ratio at low frequencies, allowing the use of lower low-cut filters. Seal Sentinel electronics allow a lower analogue low-cut filter (2 Hz) to be used in recording, providing:

•Better penetration of the earth and imaging of deep targets,

•Improved ability to see below highly absorbing and attenuating geology, especially useful for subsalt and sub-basalt and below any complex overburden

•Enhanced steep dip imaging

•Greater bandwidth for seismic inversion, providing better reservoir characterization.

•Low frequencies for full waveform inversion, to provide better velocity models

•When combined with BroadSeis™ variable-depth profiles and deghosting (patents pending), signal below 2.5 Hz is regularly recorded

A fiber-reinforced jacket surrounds the strength member, providing isolation of the hydrophone. Acoustic and vibration damping materials are placed between the hydrophone and the reinforced jacket.

Sentinel streamers are a key component of the CGGVeritas BroadSeis™ technique, recording incredible bandwidth (2.5 - 155 Hz) in this example from the Gulf of Mexico.

Noise performance of a Sentinel solid streamer compared with a gel-filled streamer in a vibration tank test. The noise level of the solid streamer is up to 20 dB below that of the gel-filled streamer.

The cylindrical hydrophone assembly is embedded in the foam floatation jacket, isolated from the stress member and contains 32 noise-cancelling piezoelectric elements per group.

Outer Jacket

Embedded hydrophone

Flotation jacket

Fiber Reinforced Jacket

Electrical Wiring

Strength member (isolated from hydrophone)

32 noise-reducing Piezoelectric elements per group

Gel-Filled Streamer

Sentinel

-20dB

2 km

4.0 s

4.2 s