METHOD TO MAINTAIN TOWED DIPOLE SOURCE ORIENTATION

Apparatus and method for a steerable horizontal electric dipole source sy stem for underwater deployment as a moving source in electromagnetic surveyi ng of subsurface regions for hydrocarbons. Position locating sensors (195) a re placed near each electrode (26, 27), and means (197, 198) are provided fo r correcting the electrodes to be at the same elevation with azimuth aligned with the source tow line (11) and the electrode mid-point positioned over t he source tow line, based on instantaneous location information from the sen sors. The streamer (28) connecting the electrodes may also be monitored for shape by sensors, with corrections made by lateral and vertical control mean s disclosed herein. The invention can be applied to any marine streamer used in geophysical surveys, including a towed streamer (191) of electromagnetic or seismic receivers (192).