Schlumberger

Delta Calibrated Marine Broadband Seismic Source

Remedies for seismic source notch and ghost effects

Marine seismic source arrays generally have a notch at a frequency that depends on a number of factors, including the source depth and water velocity. The notch is caused by interference between the direct wave and the wave reflected off the sea surface (the ghost). This results in seismic data that is bandlimited at both low and high frequencies, impacting subsequent inversion and interpretation.

We developed the Delta calibrated marine broadband seismic source to specifically address the source-side ghost.

Attenuates source-side ghost and enhances low-frequency data

The multilevel source configuration of the Delta seismic source uses proven Bolt airgun subarrays to construct a source that has no notches below 150 Hz for all directions within a 20° cone from the vertical. Subarrays are towed at different depths and suitable delays are applied to the firing time of each subarray. The staggered start times reinforce the down-going wavefield and attenuate the source-side ghost. This results in a reduced ghost notch and enhanced low-frequency content.

Available in three configurations

Three Delta source configurations are available. The 3-source array comprises three subarrays towed and deployed in a V shape at 6- and 9-m depths. The 4-source array comprises four subarrays towed and deployed in a U shape at 6- and 9-m depths. The 5-source array comprises five subarrays deployed in a similar configuration at 7-, 10-, and 14-m depths. The choice of a particular Delta source configuration depends on the geophysical objectives of your survey.  

Delta source is fully compatible with the eSource bandwidth-controlled seismic source technology and the calibrated marine source (CMS) technique to remove shot-by-shot variations during acquisition.

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WesternGeco

Obtain No Notches Below 150 Hz, in All Directions

Graph shows all three Delta seismic source configurations reduced the source side ghost notch and enhanced low-frequency content.
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