A system can include a float, a winch, a line, and a collapsible fairing. The winch can be coupled to the float. The line can be associated with the winch, where the winch is configured to extend and retract the line. The collapsible fairing can surround the line. Extension and retraction of the line can cause the collapsible fairing to extend and collapse.

A ribbon-foil depressor is incorporated into a towed seismic array to provide downward lift to array sections or components. The ribbon-foil depressors may be deployed on the port and starboard spur lines or on the outboard separation ropes. The ribbon-foil depressors may be used to submerge and operate seismic equipment at depths as low as 60 m or more and are capable of maintaining towed seismic streamer cables at these depths and still remain stable through various speed changes and turns.

A control system provides steering control commands to a steering actuator of a steering device on a piece of towed marine equipment. A memory in the control system stores setpoint data including positional values for a desired position of the piece of towed marine equipment. A control module is configured to receive the setpoint data, receive process data representing a calculated actual position of the piece of towed marine equipment; and calculate a control command for the steering actuator of the steering device based upon the setpoint data and the process data. A disturbance adjustment calculation module is configured to combine a disturbance value based upon a measured disturbance with a value of the process data and output a disturbance adjustment value. A correction calculator module adds the disturbance adjustment value to the control command to create an adjusted control command for transmission to the steering actuator.

A seismic data acquisition positioning apparatus is provided. The apparatus can include a seismic data acquisition unit. The unit can include a case having an internal compartment. The unit can include a power source, a clock, a seismic data recorder, a control unit, and at least one sensor disposed within the case. The apparatus can include a hanging unit including a beacon unit. The apparatus can include a connector having a first end coupled with the seismic data acquisition unit and having a second end coupled with the hanging unit. The connector can pivot about the first end of the connector.

A control system provides steering control commands to a steering actuator of a steering device on a piece of towed marine equipment. A memory in the control system stores setpoint data including positional values for a desired position of the piece of towed marine equipment. A control module is configured to receive the setpoint data, receive process data representing a calculated actual position of the piece of towed marine equipment; and calculate a control command for the steering actuator of the steering device based upon the setpoint data and the process data. A disturbance adjustment calculation module is configured to combine a disturbance value based upon a measured disturbance with a value of the process data and output a disturbance adjustment value. A correction calculator module adds the disturbance adjustment value to the control command to create an adjusted control command for transmission to the steering actuator.

An apparatus for surveying includes at least one survey cable, each survey cable having a proximal end attached to a mother vessel, a distal end connected to at least one subsurface towing vessel, and at least one survey device connected to the survey cable between the proximal end and the distal end. The survey cable extends in a direction perpendicular to a longitudinal axis of the mother vessel during a survey. The survey cables extend a distance E sideways from the mother vessel, for example under an ice cap, e.g. solid ice or ice floes. When surveying in a polar region, the mother vessel needs only to break a narrow channel in order to survey a large area, thus saving energy, time and money.

Foil systems for steering source and receiver arrangements for gathering seismic data are connected to buoys supporting seismic sources and receivers. Each foil system includes a positive buoyancy device, a pair of control cables, a plurality of foil sections, and an actuator. The pair of control cables may be attached to the buoyancy device and extend downward from the buoyancy device to a submerged end. The plurality of foil sections may be disposed along the control cables between the buoyancy device and the submerged end. The actuator may be configured to adjust attack angles of the foil sections by changing a tension in one or both of the control cables. Steering control is provided through a number of modes described by data distributed through a control system in communication with the foil systems.

Disclosed is an ocean bottom seismic node for recording seismic signals on the seabed. The ocean bottom seismic node may comprise an arched cathedral buoyant body coupled to a substantially flat bottom metal plate. The buoyant body may be formed of hard plastic (such as plastic injection in a mold) and have one or more cathedral type inner structures with columns that form a plurality of interconnected inner chambers, which may be dry or filled with foam and/or act as ballasts. One or more electronic components may be directly attached to the bottom metal plate (and within one or more of the internal cathedral chambers) and covered/protected by the buoyant body that is water and pressure resistant at seabed depths. The edge(s) of the buoyant body may seal around the metal plate on one or more peripheral edges of the plate and buoyant body.

A tow body arrangement for a towable device in a sonar system includes a bridle having a front for connecting to a first tow cable and back for connecting to a second tow cable. The tow body arrangement also includes a tow body rotatably connected to the bridle between the front and back of the bridle. The tow body is shaped to generate hydrodynamic forces tending to rotate the tow body perpendicular to a longitudinal axis of the bridle.

Apparatus and methods for measurement of pore pressure in rock formations through an open, or cemented and/or cased, borehole are described. Such measurements are achieved using the Dynamic Acoustic Elasticity (DAE) method for characterizing nonlinear parameters by perturbing a selected rock formation volume with a High Amplitude, Low Frequency (HALF) acoustic strain wave, and probing this volume using a Low Amplitude, High Frequency (LAHF) acoustic wave. Time reversal techniques may be employed for focusing acoustic energy Into the formation in the vicinity of the pipe or open hole.