Rough-sea deghosting using a single streamer and a pressure gradient approximation

摘要

We present a method for receiver ghost correction of towed streamer data that accounts for the rough sea surface. The method explicitly uses the fact that the pressure is zero at the free (sea) surface to estimate the vertical pressure gradient. Continuous elevation measurements of the wave height directly above the hydrophones are required―a measurement which is currently unavailable. The new deghosting method is fundamentally limited to frequencies below the first ghost notch. The lowest-order implementation requires that the streamer is towed no deeper than approximately 6 m and a receiver spatial sampling interval of about 3 m or less. Using the lowest-order and simplest implementation of the new method, the rough-sea error is reduced from 1.5-2.5 dB to about 1-1.5 dB in amplitude and from 20° to 10° in phase, at 50 Hz in a 4-m significant wave height sea. Higher-order terms in the approximation promise to further reduce the error.