| 摘要 |
A seabed receiver for marine controlled source EM (CSEM) and magneto-telluric (MT) surveying has a central unit 10 and a plurality of sensor arms 16. Each arm is mounted to the central unit by an arm mount 42,44 via which the arm can rotate. Each arm mount cooperates with a tensioning element 50 which exerts an increasing corrective force on the arm when the arm is rotated away from horizontal towards the vertical, so the arm will always be urged to regain its horizontal position when it is aligned partly or fully upwards. This folding arm arrangement allows the receivers to be deployed from a moving vessel through a chute. When a receiver drops out of the end of the chute into the water, the arms only partly unfold, since drag during the descent through the water keeps them oriented upwards. Once the receiver lands on the seabed, the arms fold out to the horizontal position under torque exerted by the tensioners. During recovery, the arms fold down, speeding ascent of the receiver to the sea surface. Also disclosed is a chute for deploying seabed receivers from a marine survey vessel and a recovery buoy for seabed receivers. |
