Determination of streamer depth and sensor calibration from dual-sensor streamer data

Dual-sensor streamer acquisition allows the incident wavefield to be decomposed into up- and down-going parts. This operation can be performed for any arbitrary recording surface, and the data can subsequently be redatumed to emulate any desired acquisition geometry. In order to take advantage of this flexibility, it is necessary that the streamer profile is accurately known. In this paper, we demonstrate that dual-sensor streamer data can be used to derive the streamer depth profile. This is achieved by cross-ghosting, whereby the pressure data are convolved with the particle velocity ghost and vice versa such that they should be identical. The optimum apparent depth that minimizes the residual error in the cross-ghosted data can be derived for each shot and channel independently. This apparent depth shows the imprint of the rough sea surface, which can be eliminated by averaging the results for many shots. This procedure provides an independent verification of the information obtained from the depth sensors in the streamer, which can be used to identify calibration problems such that they can then be rectified whilst the survey is ongoing. After finding the optimal depth, the remaining residual error can be used to determine residual errors in the sensor calibration. These errors are shown to be very small.