A simple method of magnetic declination fluctuation correction for long single-streamer positioning in a seismic survey

In single‐streamer acquisition, the use of acoustic transducers to constrain the receiver positions is not possible, thus implying the use of compass birds to gather information on the streamer location. The compasses are, however, sensitive to the declination of the local magnetic field of the earth, and local fluctuations not accounted for can degrade the accuracy of reconstructed positions. In order to correct these small‐scale fluctuations, we propose a simple deterministic method to calculate a spatial correction to apply to the compasses that enhances the positioning accuracy. The local compass declination is calculated after a first reconstruction on the whole survey area. This method was applied with success to navigation data from a 3D survey offshore Japan, and the positioning accuracy was improved to the level of the DGPS accuracy.