A foil system is used with a towed marine cable array to provide downward, upward or lateral lift to the array. The foil system can be coupled with the cable and configured to bias the submerged payload toward a target position. The foil system can include a group of foil sections each having a leading edge collectively defining an angle of attack, and a group of through-cables supporting the group of foil sections within the foil system. A subset of through-cables of the group of through-cables are arranged through front halves of the group of foil sections. This subset of through-cables can be selectively tensionable, and manipulatable to define a tensioned one of the subset of through-cables as being offset from a chord that is defined between the leading edge and a trailing edge of any of the foil sections. The foil system can thus induce one or more angles of attack for the group of foil sections, based on a rotational constraint defined by the tensioned one of the through-cables.

The invention relates to an arrangement for seismic acquisition the spacing between each adjacent pairs of receiver and sources lines is not all the same. Some receiver and/or source lines and/or receiver and/or source spacings are larger and some are smaller to provide a higher quality wavefield reconstruction when covering a larger total area or for a similar total area of seismic data acquisition while providing a wavefield that is optimally sampled by the receivers and sources so that the wavefield reconstruction is suitable for subsurface imaging needs.

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.

Apparatus and methods are disclosed relating to a body towable behind a vessel in a body of water, an arm rotatably coupled to the body, and one or more foils disposed on the arm. The arm, when deployed, is configured to be free to rotate as the apparatus is towed through the body of water. The one or more foils are configured to generate lift as the apparatus is towed. Due to the free rotation of the arm, the foils impart tension force to the body and not torque forces.

The invention relates to a seismic streamer (1) for underwater towing at a towing speed in ice-free or wholly or partially icy water, the streamer (1) is provided with birds (2) spaced along the streamer, the streamer including the birds (2) has negative buoyancy, the birds have wings (8) which can be set so that the birds during movement in the water apply an upward or downward force on the streamer. The streamer (1) is provided with buoyant bodies (4) spaced along the streamer, the buoyant bodies are connected to the streamer by spacer elements (5), the streamer including the birds, the buoyant bodies with associated spacer elements and any other equipment together have positive buoyancy. The invention also relates to a corresponding method for securing a seismic streamer (1) from damage at a substantial reduction or cessation of towing speed when towing underwater in ice-free or wholly or partially icy water.

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.

The present disclosure is directed to a helical conveyor for underwater seismic exploration. The system can include a case having a cylindrical portion. A cap is positioned adjacent to a first end of the case. A conveyor having a helix structure is provided within the case. The conveyor can receive an ocean bottom seismometer (OBS) unit at a first end of the conveyer and transport the OBS unit via the helix structure to a second end of the conveyor to provide the OBS unit on the seabed to acquire the seismic data. The system can include a propulsion system to receive an instruction and, responsive to the instruction, facilitate movement of the case.

A stable towable submersible device includes a rigid body that is towed at a positive pitch angle relative to the device's direction of motion. An acoustic projector housing extends vertically from the rigid body. When the rigid body rolls about its roll axis, which is tilted at the positive pitch angle, the acoustic projector rolls about the roll axis changing the acoustic projector's angle of attack relative to the direction of motion and generates a restoring force causing the acoustic projector to rotate back to a generally vertical orientation.

The invention notably relates to a method for controlling depth of a seismic cable having ballasts spaced apart along its length and providing a neutral buoyancy to the seismic cable, the seismic cable being adapted for midwater data acquisition, each end of the seismic cable being connected to a respective surface autonomous vessel exerting tension on the cable through a respective lead-in cable having a negative buoyancy, the method comprising, with respect to a target depth, varying the deployed length of each lead-in cable and/or the tension exerted on the cable by each respective surface autonomous vessel. This provides an improved solution for seismic prospecting in aquatic mediums.

A body towed by a cable behind a ship and commonly referred to as a towfish, the towfish includes a structure configured to move through the water in a horizontal main direction and at least one appendage configured to generate on the towfish a downwardly directed hydrodynamic lift (P) when the towfish is moving through the water under the effect of the towing, the appendage being orientable so as to modify its lift. The towfish comprises a bracket capable of rotational movement with respect the structure about a horizontal axis perpendicular to the horizontal main direction, the cable being attached to the bracket. An orientation () of the appendage, allowing it to alter the lift (P), is dependent on an angle () formed between the bracket and the structure about the horizontal axis.