Sub-bottom Profiler (SBP)

Single channel seismic and seismic acquired using a sub-bottom profiler are often thought to be the same thing. This is not the case.

Single channel seismic typically has source separate from a single hydrophone receiver group, with a nominal offset between them i.e. there is an angular component introduced to the recorded seismic wavefield.

Sub-bottom profiler data is vertical incidence i.e. the source and receiver are combined within the SBP instrument.

There are generally three types of SBP instrument, which are all best deployed for imaging the very shallow sediments (0-10 m below seabed) required for cable route trenching. Depending on the manufacturer and survey contractor there can be a variety of useable bandwidth and penetration capabilities based on source setup and geology, however a general summary is provided below:

• Pinger Systems: Use fixed high-frequency pulses (3–15 kHz) and penetration up to 20 metres below seabed.

• Chirp Systems: Use swept frequencies (2–20 kHz) and penetration up to 15 metres below seabed.

• Parametric Systems: Generate low-frequency secondary signals (2–10 kHz) from high-frequency primary pulses and penetration up to 50 metres below seabed.

  
  

Despite lacking in vertical penetration, they can be hull-mounted to many different vessels or autonomous vessels (AUV or USV), which minimises geophysical survey costs, as there is wide global fleet of capable vessels and line turns can be fast.

Most seismic acquisition contractors will perform basic processing on the recorded SBP data, typically involving seabed tracking and noise filtering (bandpass filter to cut off low and high frequencies that are considered outside the useable frequency range). However, at RockWave we have proved with many examples that the data can be significantly improved through the application of more advanced processing technology. These enhancements can reveal clearer stratigraphic horizons, identify geohazards more effectively, and improve the representation of subsurface features like buried boulders, as demonstrated in this joint paper with Beam for EAGE GET24, which can be accessed here: https://www.earthdoc.org/content/papers/10.3997/2214-4609.202421150

Jordan Greer (Global Maritime) recently presented results of RockWave processing on SBP pinger data at the Green Volt floating wind farm development. Results from which can be seen in this blog post.

Contact us about getting much more from this affordable subsurface profiler.

Related services: UHRS Reprocessing, Seismic Acquisition Partner