Marine Seismic Surveying with Towed Components Below Water's Surface

摘要

A skeg mounts from the stern of a towing vessel and extends below the waterline. A channel in the skeg protects cables for steamers and a source (e.g., air gun array) of a seismic system deployed from the vessel. Tow points on the skeg lie below the water's surface and connect to towlines to support the steamers and the source. A floatation device supports the source and tows below the water's surface to avoid ice floes or other issues encountered at the water's surface. Seismic streamers have head floats supporting the streamers. Each of the floats has adjustable buoyancy preconfigured to counterbalance the weight in water of the towed component that the float supports. Acoustic signals from a transceiver at the vessel find locations of the towed components. A towed fish at a lower level than the towed components also uses acoustic signals with a transceiver to further refine the locations of the towed components.

主权项

1. A method of constructing a seismic spread having an arrangement of towed components to be neutrally buoyant in water when towed in a seismic survey, the towed components at least including streamers and paravanes, the method comprising:
determining immersed weight and drag of the towed components; calculating drag forces versus buoyancy required to neutrally buoy the towed components at at least one tow speed in the water based on the determined weight and drag of the towed components; configuring floatation for the seismic spread based on the calculated drag forces versus buoyancy; and constructing the arrangement of the towed components in the seismic spread with the configured floatation.