Re-deploying seismic receiver cables while carrying out a marine seismic survey

摘要

A marine seismic survey is conducted by deploying receiver cables 11 in a longitudinal direction over an active receiver area 12. A seismic source 14 is towed behind a vessel 13 to track across the active receiver area in the longitudinal direction along a first line. The source vessel is turned around and the source is towed to track across the receiver area in the reverse direction along a second line; parallel to the first. This is repeated over the whole survey area. The receivers may be picked up and re-deployed while the source 13 is being fired. The distance between the cables in a transverse direction may be greater than or equal to twice the maximum offset between the source and receivers. A seismic source is towed and fired along firing lines parallel to the receiver cables while the receiver cables are re-deployed such that the cable arrangement is indexed forwards in the transverse direction. The receiver cables may be attached to a buoy which floats beneath the surface by a rope, when a signal is sent to a control unit on the buoy, a further length of rope is released, allowing the buoy to float to the surface.