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Advances in geophysical sensor data acquisition Robert GIRAULT, Philippe ALAIN 12 th  ASF Congress, Rennes FRANCE
Contents <ul><li>Introduction </li></ul><ul><li>ECHOES Overview </li></ul><ul><ul><li>Transducer Design </li></ul></ul><ul...
Introduction <ul><li>IXSEA  manufactures a full range of product including: </li></ul><ul><ul><li>Motion Sensors </li></ul...
Introduction <ul><li>What are we trying to achieve with Sub Bottom Profilers ? </li></ul><ul><ul><li>High resolution </li>...
ECHOES Overview <ul><li>ECHOES is a Range of four Chirp based Sub-Bottom Profilers </li></ul><ul><ul><li>From low frequenc...
Transducer Design – Tonpilz Transducer <ul><li>Tonpilz Transducer: </li></ul><ul><ul><li>Stack of ceramic rings </li></ul>...
Transducer Design - Janus Helmholtz <ul><li>Janus Helmholtz: </li></ul><ul><ul><li>Two Tonpilz transducers mounted back to...
Advantage of chirp technology <ul><li>Correlation process improves the signal to noise ratio </li></ul><ul><li>Additional ...
Resolution of conventional systems <ul><li>For a monochromatic Sub-Bottom Profiler system such as a boomer or a sparker, t...
Resolution of Chirp systems <ul><li>Resolution function of the bandwidth (maximum frequency less the minimum frequency of ...
How to enlarge the bandwidth ... <ul><li>One Janus-Helmholtz transducer has  3 kHz bandwidth around 3000 Hz. </li></ul><ul...
Power versus Resolution <ul><li>Boomer  </li></ul><ul><ul><li>200J= 212dB  </li></ul></ul><ul><ul><li>26cm resolution.  </...
Towing <ul><li>Surface Tow </li></ul><ul><ul><li>Advantages </li></ul></ul><ul><ul><ul><li>Easy deployment </li></ul></ul>...
DELPH Seismic Acquisition Software <ul><li>A New Philosophy </li></ul><ul><li>Acquisition systems are generally under util...
DELPH Seismic Processing & Interpretation Software ONSHORE OFFSHORE Acquisition Storage QC Processing Interpretation XTF o...
DELPH Seismic Acquisition Software
DELPH Seismic Processing & Interpretation Software <ul><li>Whole line approach for processing </li></ul><ul><ul><li>Proces...
DELPH Seismic Processing & Interpretation Software
ECHOES 1500 Data in DELPH Seismic Interpretation
ECHOES 3500 Data in DELPH Seismic Interpretation
ECHOES 5000 Data in DELPH Seismic Interpretation
ECHOES 10000 Data in DELPH Seismic Interpretation
The Future? <ul><li>ECHOES 1500 as a source for a conventional multichannel ultra high resolution seismic system. </li></u...
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ECHOES & DELPH Seismic - Advances in geophysical sensor data acquisition

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This presentation will explain what is different and new about the ECHOES products and introduce a new approach to Sub-Bottom Profiler (SBP) data acquisition and processing which has the potential to make a real difference to workflow.

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ECHOES & DELPH Seismic - Advances in geophysical sensor data acquisition

  1. 1. Advances in geophysical sensor data acquisition Robert GIRAULT, Philippe ALAIN 12 th ASF Congress, Rennes FRANCE
  2. 2. Contents <ul><li>Introduction </li></ul><ul><li>ECHOES Overview </li></ul><ul><ul><li>Transducer Design </li></ul></ul><ul><ul><li>Power Calculation </li></ul></ul><ul><ul><li>Resolution </li></ul></ul><ul><ul><li>Comparison </li></ul></ul><ul><li>Data Acquisition </li></ul><ul><li>Data Processing </li></ul>
  3. 3. Introduction <ul><li>IXSEA manufactures a full range of product including: </li></ul><ul><ul><li>Motion Sensors </li></ul></ul><ul><ul><ul><li>OCTANS – FOG Motion Sensor </li></ul></ul></ul><ul><ul><ul><li>PHINS – High Grade INS </li></ul></ul></ul><ul><ul><ul><li>ROVINS – Construction Grade INS </li></ul></ul></ul><ul><ul><li>Underwater Positioning </li></ul></ul><ul><ul><ul><li>GAPS – Pre-calibrated USBL with embedded INS </li></ul></ul></ul><ul><ul><li>Moorings </li></ul></ul><ul><ul><ul><li>OCEANO – Light-Weight to Heavy Duty Acoustic Releases </li></ul></ul></ul><ul><ul><li>Geophysics </li></ul></ul><ul><ul><ul><li>ELICS – Side-Scan Sonar </li></ul></ul></ul><ul><ul><ul><li>SHADOWS – Synthetic Aperture Mapping Sonar </li></ul></ul></ul><ul><ul><ul><li>GRADIO/MAGIS – Gradiometer & Magnetometer </li></ul></ul></ul><ul><ul><ul><li>ECHOES – Sub-Bottom Profilers </li></ul></ul></ul><ul><ul><ul><li>DELPH – Geophysical Acquisition & Processing Software </li></ul></ul></ul>
  4. 4. Introduction <ul><li>What are we trying to achieve with Sub Bottom Profilers ? </li></ul><ul><ul><li>High resolution </li></ul></ul><ul><ul><li>Deep penetration </li></ul></ul><ul><ul><li>Efficiency – Time between acquisition and deliverable chart. </li></ul></ul>ECHOES 10000 ECHOES 5000
  5. 5. ECHOES Overview <ul><li>ECHOES is a Range of four Chirp based Sub-Bottom Profilers </li></ul><ul><ul><li>From low frequency and very high power model “deep tow boomer replacement” </li></ul></ul><ul><ul><li>To very high resolution 10kHz systems. </li></ul></ul><ul><li>ECHOES use either Janus-Helmholtz or Tonpilz transducers. </li></ul><ul><li>Acoustic output is flat (within 3dB) over the entire operating range of the transducers, thus allowing fully tuneable pulse models </li></ul>ECHOES 1500 Towable High Power 650 Hz to 2500 Hz ECHOES 3500 Hull mount High Power 1800 Hz to 5200 Hz ECHOES 5000 Towable High Power 2000 Hz to 7500 Hz ECHOES 10000 Configurable High Frequency 5000 Hz to 15000 Hz
  6. 6. Transducer Design – Tonpilz Transducer <ul><li>Tonpilz Transducer: </li></ul><ul><ul><li>Stack of ceramic rings </li></ul></ul><ul><ul><li>Heavy tail mass </li></ul></ul><ul><ul><li>Lighter head mass </li></ul></ul><ul><li>The ceramic rings are compressed between the tail and head </li></ul>ECHOES 3500 ECHOES 10000
  7. 7. Transducer Design - Janus Helmholtz <ul><li>Janus Helmholtz: </li></ul><ul><ul><li>Two Tonpilz transducers mounted back to back. </li></ul></ul><ul><ul><li>Cylindrical housing creates Helmholtz cavity. </li></ul></ul><ul><ul><li>Helmholtz resonance caused by fluid inertia. </li></ul></ul><ul><li>Resonance extends the operating frequency of the transducer at the low end of the spectrum </li></ul>Typical Signal Level response of a transducer. ECHOES 1500 ECHOES 5000
  8. 8. Advantage of chirp technology <ul><li>Correlation process improves the signal to noise ratio </li></ul><ul><li>Additional gain, referred as processing gain , is defined as: </li></ul><ul><li>PG = 10 log (B * T) where : </li></ul><ul><ul><li>B = bandwidth of the pulse </li></ul></ul><ul><ul><li>T = pulse length </li></ul></ul><ul><li>ECHOES 1500 : B = 2850 Hz T=100ms PG=24dB </li></ul><ul><li>ECHOES 5000 : B = 5500 Hz T=50ms PG=24dB </li></ul><ul><li>Measured Emitted Acoustic power: </li></ul><ul><ul><li>201dB re 1 μPa at 1m for the 1500 </li></ul></ul><ul><ul><li>203dB re 1 μPa at 1m for the 5000 </li></ul></ul><ul><li>ECHOES 1500 has an apparent acoustic power of 225dB </li></ul><ul><li>ECHOES 5000 has an apparent acoustic power of 227dB </li></ul>
  9. 9. Resolution of conventional systems <ul><li>For a monochromatic Sub-Bottom Profiler system such as a boomer or a sparker, the resolution may be calculated by: </li></ul><ul><li>R=C*L where: </li></ul><ul><ul><li>R = Resolution (m) </li></ul></ul><ul><ul><li>C = sound speed (1470 m/s) </li></ul></ul><ul><ul><li>L = Pulse Length (s) </li></ul></ul><ul><li>Typical boomer: </li></ul><ul><ul><li>At low energy, 120 µs pulse </li></ul></ul><ul><ul><li>Resolution = 17 cm </li></ul></ul><ul><ul><li>More often resolution in the range of 25 cm. </li></ul></ul>
  10. 10. Resolution of Chirp systems <ul><li>Resolution function of the bandwidth (maximum frequency less the minimum frequency of the sweep): R=C/2*B where </li></ul><ul><ul><li>B= bandwidth of the pulse (Hz) </li></ul></ul><ul><ul><li>C= Sound speed (1470 m/s) </li></ul></ul>ECHOES 1500 650-2500Hz 1.7kHz Bandwidth theoretical resolution = 25cm ECHOES 3500 1,800-5,200Hz 3.4kHz Bandwidth theoretical resolution = 21cm ECHOES 5000 2,000-7,500Hz 5.5kHz Bandwidth theoretical resolution = 13cm ECHOES 10000 5,000 -15,000Hz 10kHz Bandwidth theoretical resolution = 7cm
  11. 11. How to enlarge the bandwidth ... <ul><li>One Janus-Helmholtz transducer has 3 kHz bandwidth around 3000 Hz. </li></ul><ul><li>Mounting three tuned transducer increase the bandwidth up to 5000 Hz </li></ul>
  12. 12. Power versus Resolution <ul><li>Boomer </li></ul><ul><ul><li>200J= 212dB </li></ul></ul><ul><ul><li>26cm resolution. </li></ul></ul><ul><li>Increasing the Power of a boomer adversely impacts resolution. </li></ul><ul><li>ECHOES 1500 </li></ul><ul><ul><li>223dB </li></ul></ul><ul><ul><li>25cm resolution </li></ul></ul><ul><li>ECHOES 5000 </li></ul><ul><ul><li>227dB </li></ul></ul><ul><ul><li>13 cm resolution </li></ul></ul><ul><li>Increasing ECHOES power has no effect on resolution. </li></ul>
  13. 13. Towing <ul><li>Surface Tow </li></ul><ul><ul><li>Advantages </li></ul></ul><ul><ul><ul><li>Easy deployment </li></ul></ul></ul><ul><ul><ul><li>No sea surface reflection </li></ul></ul></ul><ul><ul><li>Disadvantages </li></ul></ul><ul><ul><ul><li>Motion </li></ul></ul></ul><ul><ul><ul><li>Vessel Noise </li></ul></ul></ul><ul><li>“ Deep Tow” </li></ul><ul><ul><li>Advantages </li></ul></ul><ul><ul><ul><li>No Vessel Noise </li></ul></ul></ul><ul><ul><ul><li>Reduced Motion </li></ul></ul></ul><ul><ul><li>Disadvantages </li></ul></ul><ul><ul><ul><li>Winch and Cable </li></ul></ul></ul><ul><ul><ul><li>Sea Surface Reflections </li></ul></ul></ul>
  14. 14. DELPH Seismic Acquisition Software <ul><li>A New Philosophy </li></ul><ul><li>Acquisition systems are generally under utilised. </li></ul><ul><ul><li>Only need basic signal processing to monitor the quality of the gathered data. </li></ul></ul><ul><ul><li>Extreme processing during acquisition can hide poor quality data, that may only come to light when it is too late to do anything about it. </li></ul></ul><ul><li>Acquisition systems must be reliable. </li></ul><ul><ul><li>The more features a software product has the larger the code base needs to be and inevitably there is more potential for bugs. Bugs are really bad in acquisition. Vessel time is expensive! </li></ul></ul><ul><ul><li>Therefore keep the acquisition simple. </li></ul></ul><ul><li>Keeping the acquisition simple involves a separate package dedicated to processing and interpretation. It no more needs a moving waterfall display … </li></ul>ONSHORE OFFSHORE Acquisition Storage QC Processing Interpretation
  15. 15. DELPH Seismic Processing & Interpretation Software ONSHORE OFFSHORE Acquisition Storage QC Processing Interpretation XTF or SEGY XTF or SEGY
  16. 16. DELPH Seismic Acquisition Software
  17. 17. DELPH Seismic Processing & Interpretation Software <ul><li>Whole line approach for processing </li></ul><ul><ul><li>Processing is no more linked to data replay. </li></ul></ul><ul><ul><li>Escape from the Change-Replay- Change-Replay- Change-Replay- cycle … </li></ul></ul><ul><ul><li>Processing changes can be done on the displayed area or the whole line without scrolling </li></ul></ul><ul><li>Whole line approach for interpretation </li></ul><ul><ul><li>Zoom from sample resolution to large geological features on-screen </li></ul></ul><ul><ul><li>Speed-Corrected and Geo-Referenced profile to perform thickness, slope measurements </li></ul></ul><ul><ul><li>Direct access to geo-referenced data at any scale </li></ul></ul><ul><li>The processing and interpretation software </li></ul><ul><li>is no more based on an acquisition package </li></ul><ul><ul><li>Video </li></ul></ul>
  18. 18. DELPH Seismic Processing & Interpretation Software
  19. 19. ECHOES 1500 Data in DELPH Seismic Interpretation
  20. 20. ECHOES 3500 Data in DELPH Seismic Interpretation
  21. 21. ECHOES 5000 Data in DELPH Seismic Interpretation
  22. 22. ECHOES 10000 Data in DELPH Seismic Interpretation
  23. 23. The Future? <ul><li>ECHOES 1500 as a source for a conventional multichannel ultra high resolution seismic system. </li></ul><ul><li>ECHOES with “INS Inside” allowing extremely accurate shot-point distance control and positioning leading to true 2D stacking of multichannel SBP data. </li></ul><ul><li>Multiple streamer 3D seismic acquisition and processing using conventional streamer technology combined with ECHOES and INS. </li></ul>

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