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EAGE Glasgow 2000

EAGE Glasgow 2000. Towards the “Silent” Seismic Source Reducing Airborne Noise from Airguns. Mark Harper Mecon Limited, Cambridge, UK. Ian Jack BP Amoco, Sunbury-on-Thames, UK Gerritt Smeets Schlumberger, Gatwick Airport, UK. Mecon Ltd. EAGE Glasgow 2000.

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EAGE Glasgow 2000

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  1. EAGE Glasgow 2000 Towards the “Silent” Seismic Source Reducing Airborne Noise from Airguns Mark Harper Mecon Limited, Cambridge, UK. Ian Jack BP Amoco, Sunbury-on-Thames, UK Gerritt Smeets Schlumberger, Gatwick Airport, UK Mecon Ltd

  2. EAGE Glasgow 2000 • Why bother to reduce airgun noise? • In environmentally sensitive areas, noise may disturb wildlife or residents • “4D” surveys can make things worse Mecon Ltd

  3. EAGE Glasgow 2000 Proposed 4D survey in Poole Harbour, Dorset (English South Coast) Mecon Ltd

  4. EAGE Glasgow 2000 Advantages and Disadvantages of the Airgun as a Transition Zone Source • High Energy Output in the Seismic Band • Instantaneous Signal (convenient on a moving ship)..but.. • High Peak-Level Acoustic Noise Mecon Ltd

  5. EAGE Glasgow 2000 How do Airguns Generate Acoustic Noise? Possible Paths: 1 4 Airgun Barge 3 2 Mecon Ltd

  6. EAGE Glasgow 2000 Field Measurements of Possible Paths: GECO-Prakla Gun Barge Mecon Ltd

  7. EAGE Glasgow 2000 Field Measurements of Possible Paths: Measurement Positions Single Gun, 0.6L capacity 1 4 3 2 Airgun Barge Hydrophone Microphone Accelerometer Mecon Ltd

  8. EAGE Glasgow 2000 Measurements Near Gun Pa Pa Microphone Hydrophone Sec Sec Mecon Ltd

  9. EAGE Glasgow 2000 Measurements On Barge Pa m/s2 Accelerometer Microphone Sec Sec Mecon Ltd

  10. EAGE Glasgow 2000 Measurements on Water 100m from Barge Pa Pa Microphone Hydrophone Sec Sec Mecon Ltd

  11. EAGE Glasgow 2000 Measurements on Land 100m from Barge Pa m/s2 Accelerometer Microphone Sec Sec Mecon Ltd

  12. EAGE Glasgow 2000 Effect of Gun Depth & Pressure on Acoustic Signal at Various Distances Mecon Ltd

  13. EAGE Glasgow 2000 Conclusions • Acoustic signal from gun is not coupled to water wave or ground roll • Propagation is omnidirectional (amplitude inversely proportional to distance) • Sound is produced either by rigid-body scattering from the raft or by nonlinear effects near the gun Mecon Ltd

  14. EAGE Glasgow 2000 Airgun Pop Mecon Ltd

  15. EAGE Glasgow 2000 What now? • A proof experiment is needed to decide whether noise is caused by scattering or by nonlinearity • If by scattering, the cure is to stand the guns off from the barge • If by nonlinearity, further investigation will be needed to decide the best method for noise reduction Mecon Ltd

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