NO20131701A1 - Seismic survey system and method using distributed sources - Google Patents

Abstract

Rigid, extended geophysical equipment is described which includes track surfaces, as well as associated methods for use in marine geophysical surveys. A device for use in a marine geophysical survey comprises: rigid, elongated geophysical equipment having a length to maximum dimension of width or length of about 1000: 1 or more, wherein the rigid, extended geophysical equipment comprises control surfaces for controlling movement of the rigid, extended geophysical equipment as it is dragged through a body of water.

Description

Cross-reference to related applications

For the present application, priority is claimed from provisional US patent application number 61/746,676, filed on December 28, 2012 entitled "Steerable Rigid-Stem Survey Method and System", the description of which is hereby incorporated by reference in its entirety.

Background

The present invention generally relates to the area of marine research. More particularly, the present invention relates, in one or more embodiments, to rigid, extended geophysical equipment comprising control surfaces, as well as associated methods for use in marine geophysical surveys.

Marine survey techniques include marine geophysical surveys, such as seismic surveys and electromagnetic ("EM") surveys, where geophysical data can be collected from beneath the Earth's surface. Geophysical surveys have applications in the exploration and production of minerals and energy to help identify locations of hydrocarbon-bearing formations. Certain types of marine geophysical surveys, such as seismic or electromagnetic surveys, may involve towing an energy source at a selected depth, usually above the seabed, in a body of water. One or more geophysical sensor streamers can be towed into the water at selected depths using the same or another vessel. The streamers are usually cables which include a number of sensors arranged thereon at separate positions along the length of the cable. The sensors may be designed to generate a signal that is related to a parameter measured by the sensor. At selected times, the energy source is activated, for example generating seismic energy or EM energy that propagates downwards into the underground rocks. Energy that interacts with interfaces, usually at boundaries between layers of rock formations, can be returned to the surface and detected by the sensors on the streamers. The selected energy can be used to derive certain properties of the underground rock, such as structure, mineral composition and fluid content, thereby providing information that is useful in the extraction of hydrocarbons.

In geophysical surveys, the geophysical equipment, such as the streamers, are usually cables stored on a drum. The streamers are usually composed of several components, such as electrical conductors, fiber optics and means for recording mechanical stresses, all bundled together and covered with a protective outer skin. The streamers can be up to several kilometers long. A lead is another common piece of geophysical equipment. The lead is typically a cable that connects the streamer to the exploration vessel, and may be stored on a drum, usually the same drum as the streamer. For the deployment, retrieval and storage of this geophysical equipment, cable handling systems are usually used. Such cable handling systems can include a storage drum in combination with washers, blocks and other turning equipment where a minor change in the cable direction occurs. Drums, often of a small diameter, can be used to take off individual sections of the streamer for repair or replacement. During operation, one of the drums holds back the tension in the deployed cable with its torque. To avoid stress concentration on the cable, it can be beneficial to have many cable turns inside the drum while force is being applied. The inner drum, which is the storage drum, is therefore often used to retain the tensile stress.

The drum causes a number of restrictions and expensive features for the geophysical equipment, especially in connection with rigid elements such as coupling devices, electronics housings and spacers for sensors. For example, the streamer should usually be able to handle large deformations as a result of storage on the drums, which limits the options available for the outer skin of the streamer. Options for treating the geophysical equipment to reduce drag and fouling may therefore be limited. Certain types of geophysical equipment, such as gel-filled cables, can also be subjected to large, unwanted deformations of shape due to storage on the drum, which prevents their reuse. For various reasons, some of the components of the geophysical equipment may be on the outside of the cable and attached via connection points to the outside. These external components cannot usually be attached to the cable until the cable is unwound from the drum during deployment. To reduce the complexity associated with this attachment process, there has been an ongoing effort to place these components inside the outer skin of the cable. Placing equipment inside the outer skin is thus not always practical as adapting a solution to incorporate these components into the cable being wound on a drum can be challenging.

In some cases, it may be desirable to control the position of this geophysical equipment, such as leads and streamers, in both the vertical and lateral directions. Control of position may be desirable for a number of different reasons, including noise reduction, effective towing, group accuracy, and depth/double-echo accuracy. Controlling the rotation of the geophysical equipment can also be useful in certain applications. Wings have been used for position control and/or rotation. The wings can typically be mounted on the geophysical equipment during deployment and removed during retrieval. Although the wings can be used for positional and/or rotational control, their use can have disadvantages. For example, placing wings in the streamers can cause increased noise. As the streamers can usually be soft, elastic structures such as cables, the lateral force from the wings in particular will cause the generation of noise by deformation due to cross-flows caused by deformations at the intersection between the wings and the streamer. Another disadvantage that can occur in connection with fins is exposure to marine fouling in the water which can cause increased wear and tear and reduce lifespan. Yet another disadvantage associated with wings is increased workload for crews and hazardous operations that require manual intervention during deployment and retrieval for assembly and removal of the wings. Additional space may also be required on the vessel for separate wing storage.

There is therefore a need for equipment that can have position and/or rotation control.

Brief description of the drawings

These drawings illustrate certain aspects of some of the embodiments of the present invention and should not be used to limit or define the invention.

Figure 1 illustrates the winding of geophysical equipment on a drum.

Figure 2 illustrates winding a cable comprising rigid, extended geophysical equipment on a drum in accordance with an exemplary embodiment. Figure 3 illustrates an exemplary embodiment of a marine geophysical survey system using a rigid sensor streamer. Figure 4 illustrates an exemplary embodiment of a marine geophysical survey system using a rigid introduction. Figure 5 illustrates another embodiment of a marine geophysical survey system that uses a rigid introduction and a rigid sensor streamer. Figures 6 and 7 illustrate an embodiment of rigid, extended geophysical equipment having wings. Figures 8 and 9 illustrate another embodiment of rigid, extended geophysical equipment having wings. Figure 10 illustrates an exemplary embodiment that uses vanes to control rotation of a segment of the rigid, extended geophysical equipment. Figures 11-13 illustrate design examples of different wing designs for use on rigid, extended geophysical equipment. Figures 14-17 illustrate design examples of the use of a sleeve to regulate wing angle. Figure 18 illustrates an embodiment of rigid, extended geophysical equipment comprising a balancer. Figure 19 illustrates an exemplary embodiment of rigid, extended geophysical equipment comprising a ballast tank. Figure 20 illustrates a rigid trunk unit having the flexible connection between rigid trunks in an open position, in accordance with embodiments of the present invention. Figures 21A to 21C illustrate rigid stems having different cross-sections in accordance with embodiments of the present invention. Figures 22 and 23 illustrate the deployment of a rigid trunk unit from an exploration vessel where a release device holds the rigid trunk unit in accordance with embodiments of the present invention. Figure 24 illustrates the use of a stem joint to close the flexible connection between adjacent rigid stems in accordance with embodiments of the present invention. Figure 25 illustrates another embodiment which uses a stem joint to close the flexible connection between adjacent rigid stems. Figures 26 and 27 illustrate the use of a locking pin to close the flexible connection between adjacent rigid stems, in accordance with embodiments of the present invention. Figures 28 and 29 illustrate the use of an extensible rod to close the flexible connection between adjacent rigid stems in accordance with embodiments of the present invention. Figures 30 and 31 illustrate the use of an extendable rod with a stop hinge to close the flexible connection between adjacent rigid stems in accordance with embodiments of the present invention. Figures 32 and 33 illustrate the use of a protective cover over the flexible connection in accordance with embodiments of the present invention. Figures 34 and 35 illustrate the use of a protective cover to close the flexible connection in accordance with embodiments of the present invention. Figures 36 and 37 illustrate the connection of two rigid stem units in accordance with embodiments of the present invention. Figures 38 and 39 illustrate an exemplary embodiment of rigid, extended geophysical equipment that includes spacers that may be aligned in a rigid line to provide rigidity. Figure 40 illustrates a conventional seismic survey system.

Detailed description

The present invention generally relates to the area of marine research. More particularly, the present invention relates, according to one or more embodiments, to rigid, extended geophysical equipment comprising control surfaces and associated methods for use in connection with marine geophysical surveys.

Embodiments of the rigid, extended geophysical equipment may include control surfaces that enable control of the geophysical equipment. The control surfaces can, for example, be designed to enable control of a particular geophysical instrument's depth and/or lateral positioning. As a further example, the control surfaces can be designed to enable rotational control of the geophysical instrument. The control surfaces may also enable the rigid, elongated geophysical equipment to perform a desired motion while in the water, such as a wave motion, a surfacing, a submersion, a salvage or retrieval. Examples of suitable control surfaces include, but are not limited to, wings, balancers and other rudders, among many others. Designs of the control surfaces can be connected to the geophysical equipment during deployment or can be retractable.

The guide surfaces can be used in conjunction with any of a wide variety of rigid, elongated geophysical equipment having a ratio of length to greatest width dimension to height (diameter for a cylindrical instrument) of about 1000:1 or more. A rigid, elongated geophysical instrument having, for example, a maximum width and height of about 100 millimeters may have a length of at least about 100 meters, one having a maximum width and height of about 75 millimeters may have a length of at least about 75 meters, or one that has a maximum width and height of about 25 millimeters, can have a length of at least about 25 meters. In some embodiments, the greatest dimension of the width and height of the rigid, elongated geophysical instrument may average about 25 millimeters or more. In some embodiments, the rigid, elongated geophysical instrument may have a length ranging from, for example, 200 meters to about 2000 meters or longer. In some embodiments, the length of the rigid geophysical instrument can have a length of up to about 16,000 meters, which can for example be used at towing depths of from a few to many hundreds of meters.

The rigid, elongate geophysical equipment (when installed and in operation) is characterized as rigid in that it has a bending, torsional and/or linear stiffness that can be maintained over considerable lengths, for example up to about 10 meters, about 50 meters, about 100 meters or even longer. Embodiments of the rigid, extended geophysical equipment may be characterized as rigid over a length of about 25 meters or longer, where the geophysical instrument has a minimum width or height of about 1 meter or less. The rigid, extended geophysical equipment may include any of a wide variety of equipment components that may be used in conjunction with seismic, electromagnetic, or other types of marine surveys, where a sensor or other measurement device may be used to collect data while being towed through a body of water. For example, the rigid, extended geophysical equipment can be used in conjunction with a wide variety of marine surveys that use towed sensors, such as acoustic sensors, motion sensors, EM sensors, sonar, or other suitable marine survey sensors. In all of these applications, the rigid, extended geophysical equipment can preferably be used in conjunction with the rigid trunk assembly rather than the coiled towed busbar concept that has been used in the past. Examples of suitable rigid, extended geophysical equipment include, but are not limited to, sensor cables, leads, and towed geophysical sources. Sensor streamers can be elongated equipment that can include a number of geophysical sensors arranged on it at separate positions. Launches can be elongated equipment used to tow geophysical instruments such as sensor streamers and geophysical sources from an exploration vessel. Towed geophysical sources can be an instrument towed from an exploration vessel, and which can be activated to generate, for example, seismic energy or electromagnetic energy.

In some embodiments, the rigid, elongated geophysical instrument may comprise a number of interconnected rigid stems. The rigid stems can be assembled on an exploration vessel to form the one or more rigid stem units that can be deployed in the water. In alternative embodiments, the rigid, elongated geophysical instrument may include a number of spacers that may be aligned in a rigid line to provide rigidity to the geophysical instrument. Components, such as electrical or optical conductors, geophysical sensors and other electronics, can be arranged in the geophysical equipment, for example in the rigid trunks. Control surfaces (such as wings, balancers, rudders, etc.) can be included on the geophysical equipment for control or regulation of, for example, rotation. The rigid, elongated geophysical instrument may have a round cross-section or have other cross-sectional shapes, such as wing-shaped cross-section for low drag or asymmetric cross-section for optimization of properties or response. The rigid geophysical instrument may, for example, have an oval, circular, rectangular, square, pentagonal, other polygonal, wing-shaped or non-symmetrical cross-section.

Unlike cables and structures that have been used in the past as leads and streamers, the rigid, elongated geophysical equipment in the operational configuration will not typically form catenary, sinusoidal, hyperbolic, or parabolic curvatures over at least part of its length, but will instead usually exhibit elastic behavior with deformation similar to the deformation of beams. Embodiments of the rigid, extended geophysical equipment when mounted cannot be stored and deployed from a drum, but instead can use a movable or fixed attachment point for deployment from an exploration vessel. The attachment point may hold embodiments of the rigid, elongated geophysical equipment by means of friction (for example, wheels) or, for example, a ring. In alternative embodiments, the rigid, elongated geophysical instrument can have a variable stiffness that can be activated after deployment in the water. The instrument with variable stiffness can have a storable design where the instrument is flexible and have a working configuration where the instrument is rigid. The rigid, extended geophysical instrument can, for example, have a storable design where the instrument can be deployed and stored on a drum on board, for example, an exploration vessel. After deployment in the water, the streamer can, for example, be changed from the storable design to the operational design. The geophysical investigation can then be carried out with the streamer in the operative embodiment.

In some embodiments, the rigid, extended geophysical instrument (when installed and operational) may have a bending stiffness of 700 Newton square meters ("Nm<2>") or more over significant lengths (eg, over about 25 meters or more). . The rigid, elongated geophysical instrument may, for example, have a bending stiffness of 700 Nm<2> over substantially its entire length. The stiffness of 700 Nm<2>corresponds to a stiffness in a cantilever beam with a length of 1 meter which is fixed at one end and has a load of 1 Newton at the other, and which deforms around 0.5 mm under the load. This corresponds to an aluminum tube (with modulus of elasticity of 70 GPa) with an outer diameter of 2 inches and a thickness of 0.02 mm, a steel tube (with modulus of elasticity of 210 GPa) with an outer diameter of 2 inches and a thickness of 0, 03 mm or a circular rod with a modulus of elasticity of 2 GPa. Each of these elements, that is, the aluminum tube, the steel tube and the circular rod, are examples of elements with a bending stiffness of 700 Nm<2>. An outer diameter of 2 inches usually requires a deformation of 5% to be wound on a 2 meter drum, which is difficult for most materials. Stiffer materials can be deformed a maximum of 0.1% or in extreme cases 1% so that they cannot be wound on a drum without being wound in a wire or busbar. Materials with lower strength may be able to deform, but will then be too soft to enable bending.

Embodiments of the rigid, elongated geophysical instrument (when assembled and in operation) may have a stiffness that makes it difficult to wind the instrument on or off a drum. The stiffness will generally produce a flex arm for the instrument when wound on or off. This distance multiplied by the tensile stress can produce the load (known as the "critical load") that the rigid, elongated geophysical instrument carries in its cross-section at the first point of contact with the drum. The point of contact may be at or in front of the tangential point between the drum and the rigid extended geophysical instrument, where the tangential point corresponds to no stiffness in the rigid extended geophysical instrument and a bending arm equal to zero. Figures 1 and 2 illustrate the winding of a geophysical instrument 1 on a drum 2. The bending arm is represented in figure 1 by an arrow 3. The input voltage is represented by an arrow 4. The torque is represented by an arrow 6. As shown, the geophysical instrument 1 has a loaded cross-section 7, which is the first point of contact with the drum 2 and which transmits the critical load described above. Although the geophysical instrument 1 shown in Figure 1 may have a certain bending stiffness, it can still be wound on the drum 2. In the embodiment shown in Figure 2, the geophysical instrument 1 may further contain a rigid body 8 which produces a bending limitation when wrapping the thumb 2.

Equipment previously used in marine surveys usually has several contributors to the boom arm. Sensor streamers can, for example, have amplifiers, coupling devices, sensor housings and the like that can contribute to the bending arm. Bending restrictors may also be placed at the ends to protect the wires lying within, which may contribute to the bending arm. Leads can also have several different contributors to increased flex arm, including reinforced bus cables such as gel filled, soft stiffened or the like, and real solids such as nylon, polyurethane or mixtures thereof. For previous equipment used in marine seismic surveys, the flex arm has been less than 0.3 meters under a load of 3 kiloNewtons ("kN"). Some types will have almost the same bending arm for different loads (typically hinge joints and rigid bodies), others will deform greatly under increasing load and thus reduce the bending arm (as the load increases), but all materials have limited stiffness and have some deformation even if the deformation can be very difficult to detect. Embodiments of the present invention can be used in conjunction with rigid, extended geophysical equipment (when installed and in operation) with a stiffness greater than 700 Nm<2>. This is stiffer than other cable or streamer-based equipment that has been used so far, and the bending arm can consequently be larger than 0.3 metres. The rigid, extended geophysical equipment may thus be at risk of being damaged or permanently deformed when subjected to 3 kN or more, and thus winching may not be a good handling method for certain embodiments.

Figure 3 illustrates a marine geophysical survey system 5 in accordance with embodiments of the present invention. In the illustrated embodiment, the system 5 may include an exploration vessel 10 which moves along the surface of a body of water 15, such as a lake or an ocean. The exploration vessel 10 may include equipment, shown generally at 20 and collectively referred to hereinafter as a "recording system". As an example, the recording system 20 may include one or more devices (none shown separately) for determining the geodetic position of the exploration vessel 10 (for example, a receiver for receiving signals from satellites included in a global positioning system), determining and providing a time-indexed registration of signals generated by each of a number of geophysical sensors 25, and/or for activation of one or more energy sources 30 at selected times.

The exploration vessel 10 or another vessel (not shown) can tow a source cable 35 that includes one or more energy sources 30. As shown, the energy sources 30 can be towed over the waterbed 40, where the energy sources 30 are decoupled from the waterbed 40. In some embodiments (not shown) one or more of the energy sources 30 may be mounted to the hull of the exploration vessel 10. The energy sources 30 may be any selectively activatable source suitable for undersea geophysical surveys, including, but not limited to, seismic air guns, water guns, vibrators, EM transmitters or groups with such devices. When energy is emitted by the energy sources 30, it propagates downward through the body of water 15 and rock formations 45 below the water bed 40. It should be noted that although the present example shows only two energy sources 30, the invention can be used in connection with any number of energy sources which is towed by the search vessel 10 or another vessel.

The geophysical survey system 5 may include rigid, extended geophysical equipment, such as a rigid sensor streamer 50 towed by the exploration vessel 10 (or another vessel). As shown, the rigid sensor streamer 50 may include geophysical sensors 25 at discrete positions. In the embodiment shown, the rigid sensor streamer 50 can for example be formed by connecting a number of rigid streamer stem units 55 end to end. As shown, two rigid streamer stem units 55 may be connected end to end, for example at a connection point or a streamer stem joint 65. It is contemplated that more than two rigid streamer stem units 55 may be used in embodiments of the present invention. Each of the rigid streamer stem units 55 may comprise a number of interconnected rigid streamer stems 60. The streamer stem joints 65 may be provided at the junction between adjacent rigid streamer stems 60 to mechanically join the adjacent rigid streamer stems 60. Although not shown, a streamer stem joint 65 need not be used, in some embodiments, in order to connect at least one pair of adjacent rigid streamer stems 60, an open joint may be left. As previously mentioned, certain components (for example, conductors, geophysical sensors 25, and other electronics) can be arranged in the rigid streamer stems 70. Sensors such as motion sensors, for example, can be arranged inside the rigid streamer stems 60 where sensing of water movement in relation to the streamer 50 is the movement sensed by the rigid streamer stems 60. As a further example, channels or other membranes (not shown) may be provided in the rigid streamer stems 60 for geophysical sensors, such as hydrophones that receive pressure signals from the water body 15. An Introduction 70 can connect the streamer 50 the exploration vessel 10.1 the embodiment shown, the introduction 70 can comprise a cable.

Although the present example shows only one streamer 50, the invention can be used in connection with any number of laterally and/or vertically separated streamers towed by the search vessel 10 or another vessel. In some embodiments, for example, eight or more streamers may be towed by the search vessel 10, while up to twenty-six or more streamers may be towed by the search vessel 10 in other embodiments. When towing many streamers (such as the streamer 50 in Figure 3) containing the rigid streamer stem units 55, the streamers can preferably be held at independent positions both laterally and vertically (relative to the towing path). One of the streamers can, for example, be kept at or near the surface, while other streamers can be positioned deeper in the water mass 15. In some embodiments, the streamer 50 can be towed at a depth of up to about 25 meters. In alternative embodiments, the streamer 50 can be towed at a greater depth than that usually used in connection with seismic surveys. The streamer 50 can, for example, be towed at a depth of up to about 50 meters or more.

The geophysical sensors 25 can be of any type known in the field. Non-limiting examples of such sensors may include seismic sensors such as geophones, hydrophones or accelerometers, or EM field sensors such as electrodes or magnetometers. Additional examples of sensors may include depth sensors, acoustic transponders and transducers. In the illustrated embodiment, the geophysical sensors 25 are included in the rigid streamer stems 60. The geophysical sensors 25 can, for example, generate response signals, such as electrical or optical signals, in response to the detection of energy emitted from the one or more energy sources 25 after the energy has interacted with the rock formations (not shown) under the water bed. Signals generated by the geophysical sensors 25 can be communicated to the recording system 20.

Although not shown in Figure 3, additional sensors, actuators, transducers, and other electronics (eg, tanks, batteries, etc.) may also be included in the rigid streamer stems 60. Examples of sensors (eg, the geophysical sensor 25 in Figure 1) that may be incorporated include sound/pressure sensors, motion sensors (speed, velocity and/or acceleration), EM sensors, magnetism (eg compass), pressure sensors, depth sensors, tilt sensors, strain sensors, surface or bottom echo sensors/mappers among others.

In some embodiments, one or more activators may be included in the rigid streamer stems 60. Examples of activators may include control surfaces, ballast tanks, openings, covers/lids, and connection points, among others. Control surfaces (such as wings, rudders, etc.) for steering or regulating rotational position can be used, for example. As previously mentioned, the control surface can act to provide depth and/or lateral control of the rigid streamer stems 60. The control surfaces can further enable the rigid streamer stems 60 to perform a desired movement in the water, such as a wave movement, diving to the surface , diving, rescue or retrieval. Ballast tanks may also be included which may allow the rigid streamer stems 60 to remain at a certain depth, submerge to the surface or compensate for water ingress, such as when gas filling a flooded chamber in the rigid streamer stem 60. Openings may also be provided. for access to sensor surfaces, ballast and/or gravity/mass point manipulation. Connection points that can be opened and/or closed can also be provided in the rigid streamer stems 60, such as valves or openings for feed or transfer lines. Covers/lids that can be opened and/or closed can also be provided, which can enable cleaning and/or streamlined handling, for example.

Although Figure 3 illustrates the use of rigid, extended geophysical equipment as a sensor streamer (eg, the rigid sensor streamer 50), embodiments may include the use of other rigid, extended geophysical equipment, such as, for example, leads and towed geophysical sources. Figure 4 illustrates an alternative embodiment of the marine seismic survey system 5 that uses a rigid lead 75. In the shown embodiment, the rigid lead 75 comprises a number of interconnected rigid lead stems 80. As shown, the rigid lead stems 80 can be connected end to end, for for example by means of lead-in stem joints 85. The rigid lead-in 75 can be used, for example, to deploy the sensor streamer 90 from the exploration vessel 10 and to hold the sensor streamer 90 at a selected distance behind the exploration vessel 10. In the embodiment shown, the sensor streamer 90 comprises a cable 95 with geophysical sensors 25 arranged on this at separate positions.

Figure 5 illustrates an alternative embodiment of the marine seismic survey system 5, which comprises a rigid streamer 50 deployed behind an exploration vessel 10 using a rigid inlet 75. As shown, the rigid streamer 50 may be formed by connecting two rigid streamer trunk units 55 end to end in accordance with embodiments of the present invention. In the illustrated embodiment, the rigid streamer can be connected to the exploration vessel 10 by means of a rigid lead-in 75, which can comprise interconnected rigid lead-in stems 80, as shown in figure 4. A flexible connecting element 100 can, for example, connect the rigid lead-in 75 with the rigid streamer 50, so that the rigid streamer 50 can extend in a different direction in the body of water 15 than the rigid introduction 75. In some embodiments, the flexible coupling element 100 can provide passive or active control of the angle between the rigid introduction 75 and the rigid the streamer 50, and the active control can use remote-controlled activators as ordinary experts in the field will understand after familiarizing themselves with this description.

As previously mentioned, embodiments of the rigid, extended geophysical equipment include control surfaces (such as wings, balance rudders, rudders, etc.) for controlling or regulating, for example, rotation. Figure 6 illustrates a rigid, elongated geophysical device 105 comprising wings 110a, 110b. As illustrated, the equipment 105 may comprise a rigid stem 115 comprising a stem body 120. The wings 110a, 110b may extend from the stem body 120 in accordance with embodiments of the present invention. As shown, for example, the rigid, elongated geophysical equipment can be towed in or near the horizontal plane. The direction of flow is illustrated in Figure 6 by an arrow 125. For embodiments where, for example, an inlet is used, the lateral angle a between the rigid stem 115 and the direction of flow 125 may be small near the path of the exploration vessel 10 and larger for external inlets with a lateral angle a of up to about 60° or more in some embodiments.

As shown, one of the wings 110a, 110b may extend upwards (that is, away from the water bottom 40) from the stem body 120, and one of the wings 110a, 110b may extend downwards (that is, towards the water bottom 40) from the stem body 120.1 the shown embodiment, the wings 110a, 110b may be designed to provide, for example, lateral force, to position the rigid streamer instrument 105 in a selected lateral position. In embodiments of the introductions, the rigid streamer equipment 105 may be used to position the forward ends of the towed sensor streamer (eg, sensor streamer 90 in Figure 4) in a selected lateral position. In some embodiments, the wings 110a, 110b may be retractable. The wings 110a, 110b can for example be folded into the rigid, extended geophysical equipment 105. By being able to unfold the wings 110a, 110b to an open position, the rigid, extended geophysical equipment 105 can be activated for lifting after deployment. In some embodiments, the wings 110a, 110b can be unfolded after deployment in the body of water 15 to move into the selected lateral position. In some embodiments, the stem body 120 may have a wing cavity 130 to receive the wings 110a, 110b. In a closed embodiment, the wings 110a, 110b can be held together and stored in the wing cavity 130. To open and close the wings 110a, 110b, any of a number of different and suitable techniques can be used. In some embodiments, a wing-covering stem sleeve 135 may cover the wings 110a, 110b and hold them in the wing cavity 130. In alternative embodiments, the wings 110a, 110b may be opened using hinges or joints (not shown) which may be automatic or manually operated, in combination with springs (not shown) or biasing of the wings 110a, 110b.

The wing-covering stem sleeve 135 can be arranged over at least part of the stem body 120 and be slidably movable on the stem body 120. The wing-covering stem sleeve 135 can, for example, be designed for movement on the stem body 120 and uncover the wings 110a, 110b. A threaded screw or other suitable mechanism (not shown) may be used to drive the vane-covering stem sleeve 135. In some embodiments, the vanes 110a, 110b may be biased, for example by means of a spring (not shown), such that uncovering of the vanes 110a, 110b causes the wings 110a, 110b to open. To close the wings 110a, 110b, the wing-covering stem sleeve 135 can be brought back over the wings 110a, 110b to cause the wings to fold back into the wing cavity 130. The rigid stem 115 can further comprise a wing cavity stem sleeve 140 placed over at least a portion of the stem body 120 and slidably movable on the stem body 120. The wing cavity stem sleeve 140 can be moved to cover the wing cavity 130, for example to prevent drag caused by having an opening in the rigid stem 115. The wing covering stem sleeve 135 and the wing cavity stem sleeve 140 can have the same shape as the stem body 120, for example to reduce drag of the rigid stem unit 220. By covering the wings 110a, 110b with a stem sleeve 135 that has almost the same shape as the stem body 125 itself, the smoothness of the wing area can remain intact when the wings 110a, 110b is in the closed position. In this way, an almost identical diameter and surface texture can be preserved in the closed position while the wings 110a, 110b are hidden and protected in the wing cavity 130. Accordingly, when retracted into the wing cavity 130, the wings 110a, 110b cannot create any additional drag compared to conventional wings that can create significant drag even when not being used to produce hydrodynamic lift.

In alternative embodiments (not shown), the wings 110a, 110b can be mounted on the stem body 120 when deployed from the exploration vessel 10 and removed from the stem body 120 when retrieved from the body of water 15. The wings 110a, 110b can, for example, be mounted on the stem body 120 using a snap-on attachment (not shown) or another suitable connection mechanism. The retractable wings 110a, 110b can preferably be mounted in the rigid trunk, as they do not require any manual intervention when deployed or picked up on the exploration vessel (for example the exploration vessel 10 in Figure 3). In this way, the workload on the crew and dangerous operations can be reduced by using the wings 110a, 110b which are retractable. The wings 110a, 110b, which are retractable, also do not need to require separate storage space on the search vessel.

The wings 110a, 110b can be mounted on the stem body 120 so that the wings 110a, 110b extend at an angle p from the vertical in relation to the flow direction 125. In this way, the wings 110a, 110b can provide lateral lift when moving through the water mass 15 The wings 110a, 110b can for example have an angle P less than about 90°, alternatively less than about 45<0.> and alternatively less than about 10°. As shown, vanes 110a, 110b may be considered vertical as they extend vertically or at an angle p from vertical with respect to flow direction 125. In some embodiments, vanes 110a, 110b may be attached at angle p. In alternative embodiments, vanes 110a may , 110b be connected to the stem body 120 so that the wings 110a, 110b can be moved, for example to any angle p. The wings 110a, 110b can for example be mounted to the stem body 120 by means of a shaft (for example the shaft 145 in Figure 7) which can be actuated to move the vanes 110a, 110b to the angle p. In some embodiments, one or more linear drive devices may be used to drive the vanes 110a, 110b around the vane cavity 130. In other embodiments, the vanes 110a, 110b may be mounted on a shaft that rotates freely or against one or more springs or stops. A freely rotating shaft should achieve a greater ratio between lateral force and drag resistance, and thereby be more efficient when spreading the sensor streamers and/or inserts. A freely rotating shaft may also allow the same vanes 110a, 110b to be used in different positions on the rigid, elongated geophysical equipment 105, as they may be used at different angles p. In other embodiments, the angle p may be actuated or driven by the opening/closing mechanism to change the angle p continuously or incrementally to allow active control of lift, and thereby dynamic depth and distance for the entire towed unit. Deployment of the wings 110a, 110b can for example be regulated to vary the area of the wings 110a, 110b to provide optimal lift, in contrast to conventional wings which for example always have the same exposed area. In some embodiments, another actuator may be used to drive the wing angle. In some embodiments, separate actuators may be on both wings 110a, 110b of the same stem body 120.

Although Figure 3 only illustrates a single rigid stem 115, it should be noted that two or more rigid stems 115 each having wings 110a, 110b may be used in the rigid, extended geophysical equipment 105 in accordance with embodiments of the present invention. To vary the lift generated by the wings 110a, 110b, the wings 110a, 110b on a subset of the rigid stems 115 can be opened. By leaving some or all of the vanes 110a, 110b inside the rigid, elongated geophysical equipment 105, the vanes 110a, 110b can be internally protected, for example, from marine fouling which is at least to some extent driven by exposure to sunlight. This can lead to a large reduction in the degree to which the wing mechanism and corresponding activators must move, and will potentially extend the lifetime of the wings 110a, 110b. By leaving some or all of the wings 110a, 110b inside the rigid, extended geophysical equipment 105, noise from the wings 110a, 110b themselves can also be reduced. In some embodiments, some or all of the wings 110a, 110b may be closed to reduce noise in the recorded data.

In some embodiments, the vanes 110a, 110b may be closed to reduce unwanted interaction between the rigid, elongated geophysical equipment 105 and objects in the water body. The rigid, extended geophysical equipment 105 can, for example, come into contact with an unwanted object such as fishing equipment, waste or rope located in the body of water 15. To release the object, the wings 110a, 110b on successive rigid stems 115 can be closed until the object has been freed. In this way, the wings 110a, 110b can be closed to reduce the risk of chopping up such objects, and the extra loads and steering resulting from such chopping up can be avoided.

When the vanes 110a, 110b are used in a rigid insert (for example, the rigid insert 75 in Figure 4), the different angles p, depending on the proximity of the sensor streamer and the desired lateral position, can be selected for the vanes 110a, 110b on each rigid insert . Embodiments may accordingly include different angles p used for the wings 110a, 110b on the same of the rigid inserts, while further embodiments may include different angles p for the rigid stems 115 on different rigid inserts. It should be noted that smaller wings 110a, 110b may be required on particular rigid inserts associated with the innermost of the streamers, as less lateral lift may be required.

A cross-sectional view through a rigid, elongated geophysical device 105 having wings 110a, 110b mounted on the stem body 120 is shown in Figure 7 in accordance with embodiments of the present invention. In the illustrated embodiment, the rigid, elongated geophysical equipment 105 has a flat or wing-shaped cross-section. The wings 110a, 110b are each shown folded into the corresponding wing cavity 130. As shown, the wings 110a, 110b have a profile that is asymmetrical. The wings 110a, 110b, which are asymmetrical, can be used when the wings 110a, 110b do not have to act in both directions, in much the same way as airplane wings. Asymmetric wings can have better lift performance as a function of drag, and thus small or smaller wings can be used with less noise. In some embodiments, the wing-covering sleeve 135 may be arranged over at least part of the stem body 120 and may cover the wings 110a, 110b, for example to hold each of the wings 110a, 110b in the corresponding wing cavity 130. In the shown embodiment, the wings are 110a, 110b mounted to the trunk body 120 by means of a shaft 145. The shaft 145 can, for example, be fixed or rotate freely. The stem body 120 may also define one or more internal chambers 150 where various components may be installed, such as cables 155. Although not shown, sensors, actuators, transducers, and other devices (eg, tanks, batteries, etc.) may also be incorporated into the inner chambers 150.

The wings 110a, 110b may have a size suitable for a particular application. The size of the wings 110a, 110b may depend on a number of factors, including the required lift, cavity size, aspect ratio, wingspan or angle of attack.

In some embodiments, the wings 110a, 110b may be longer than the greater of the width and height of the rigid, elongated geophysical equipment 105. In other embodiments, the length of the wings 110a, 110b may be less than the greater of the width and height of the rigid, elongated geophysical equipment 105. If the size of the wings 110a, 110b of the rigid, extended geophysical equipment 105 is reduced, more wings 110a, 110b may be required to provide equivalent lift.

Figures 8 and 9 illustrate another embodiment of the rigid, extended geophysical equipment 105 comprising wings 110a, 110b. As illustrated, the rigid, elongated geophysical equipment 105 may have a circular cross-section. Figure 8 is a perspective sketch showing the wings 110a, 110b extending horizontally from the wing cavity 130 in the rigid, extended geophysical equipment 105. Figure 9 is a cross-sectional sketch showing the wings 110a, 110b retracted into the wing cavity 130 in the rigid, extended geophysical equipment 105.

Figure 10 illustrates an embodiment showing a segment of a rigid, extended geophysical equipment 105. In the illustrated embodiment, the rigid, extended geophysical equipment 105 is in the form of a rigid stem unit comprising three rigid stems 115a, 115b and 115c. As shown, the rigid stem 115b is arranged between the other two rigid stems 115a, 115c. In the exemplary embodiments, rotation of the rigid stems 115b can be regulated by, for example, using vanes (for example, the wings 110a, 110b shown in Figures 6 and 7) so that only the rigid stem 115b is rotated to generate lift. In this way, the middle rigid stem 115b can be at a different angle than the outer rigid stems 115a, 115b, whereby lift can be generated to force down the rigid, elongated geophysical equipment 105. It should be noted that in the illustrated example, the connection between the adjacent rigid stems allow relative rotation.

As mentioned, the wings 110a, 110b of the rigid, elongated geophysical equipment 105 can have a number of different designs. For example, the vanes may extend substantially vertically or substantially horizontally from the rigid, elongated geophysical equipment 105. The term "substantially" as used herein in connection with the direction in which the vanes extend means that the vane extent may vary by as much as 20 % from the specified direction. Figures 11-13 illustrate a cross-sectional sketch of the rigid, elongated geophysical equipment 105 having different blade configurations. Figure 11 illustrates an embodiment of the rigid, elongated geophysical equipment 105 having a rigid stem 115 with a pair of wings 110a, 110b extending substantially vertically. The vertical extent of the wings 110a, 110b may for example be desirable to provide lateral lift on the rigid, extended geophysical equipment 105. Figure 12 illustrates an embodiment of the rigid, extended geophysical equipment 105 having a rigid stem 115 with a single wing 110a extending substantially horizontally from the rigid, elongated geophysical equipment. For example, the horizontal extent of the wing 110a may be desirable to provide vertical lift on the rigid extended geophysical equipment 105. Vertical lift may be used to steer the rigid extended geophysical equipment 105 or a particular segment thereof to a specified depth. Figure 13 illustrates an embodiment of the rigid, elongated geophysical equipment 105 having a rigid stem 115 with a pair of wings 110a, 110b extending substantially horizontally. Although the horizontal extent can be used to provide depth control, the horizontal extent of the wings 110a can also provide rotational control.

In some embodiments, the direction of the lift generated by the wings 110 can be regulated. The angle of the wings 110 in relation to the water flow can, for example, be adjusted to regulate the lift. This may enable the wings 110 to generate upwardly directed or downwardly directed lift, for example, depending on the particular angle. Figure 14 is an end view of an embodiment illustrating a wing 110 extending from a wing cavity 130. The wing 110 may be attached to the stem body 115 at two points 160, which may be axles. The wing 100 can rotate at points 160 to unfold, either by removing a lid/cover or by means of a mechanical actuation. The wing 110 can be designed to slide to different positions in the wing cavity 130. In some embodiments, the shape of the wing cavity 130 can be adjusted to allow adjustment of the wing angle. Figures 15-17 illustrate embodiments where the wing cavity 130 is in the form of an angled groove in the stem body 120. In some embodiments, the angled groove can be used in connection with a symmetrical wing profile. By stopping the wing-covering stem sleeve 135 at different points on the stem body 120, the wing 110 can assume a different angle in relation to the water flow. Figure 15 illustrates the wing covering stem sleeve 135 positioned with the wing 110 in a neutral configuration in accordance with embodiments of the present invention. Figure 16 illustrates the wing covering stem sleeve 135 positioned with the wing 110 in a position to provide downward directed lift in accordance with embodiments of the present invention. Figure 17 illustrates the wing-covering stem sleeve 135 positioned with the wing 110 in a position that provides upwardly directed lift in accordance with embodiments of the present invention.

Although the preceding figures illustrate the use of wings 110a, 110b with the rigid, extended geophysical equipment 105, embodiments of the present invention may also include the rigid, geophysical equipment 105 with other control surfaces, such as balancers and rudders. Figure 18 illustrates a rigid, elongated geophysical device 105 that includes at least one balancer 165 attached to the edge 170 of the stem body 120 in accordance with some embodiments. As shown, the balancer rudder 165 may extend in a longitudinal direction substantially parallel to the longitudinal axis 175 of the rigid, elongated geophysical equipment 105. The balancer rudder 165 may be movable relative to the rigid stem 120 to provide lift when the rigid, elongated geophysical equipment 105 geophysical equipment 105 is moved through the body of water 15. In addition to providing vertical lift, the balance rudder 165 may also be designed to regulate rotation of a rigid, elongated geophysical equipment 105 where the rigid stem 120 may be included. The angle of the balance rudder 165 can, for example, be regulated passively or actively to control rotation.

Design examples of the rigid, extended geophysical equipment 105 may include additional attachments or devices for depth regulation. Ballast tanks or other devices known to ordinary experts in the field can, for example, be used for depth regulation. Figure 19 illustrates an embodiment of a rigid, elongated geophysical equipment 105 that includes at least one ballast tank 180 arranged in the stem body 120. As shown, the ballast tank 180 has an internal volume 185 in fluid communication with a first opening 190. In some embodiments, a piston 195 may also be arranged in the ballast tank 180. The piston 195 may be operatively connected to a linear drive device 200 and a motor 205. The linear drive device 200 may for example operate to transform mechanical energy generated by the motor 205 to produce a rectilinear force such that the piston 195 can move in the longitudinal direction inside the ballast tank 180. In some embodiments, the inner volume 185 of the ballast tank 180 can contain sea water. Water can be drawn into, or expelled from, the inner volume 185, for example to regulate buoyancy or depth. At a desired time, seawater can be expelled from the ballast tank 180 via the first opening 190. To expel water from the ballast tank 180, the motor 205 can be used to move the piston 195, thereby forcing water from the inner volume 185 through the first opening 190. Air from the inner chamber 210 of the stem body 120 should fill the inner volume 185 as the seawater is displaced. The piston 195 can be moved in the opposite direction, for example to draw water into the inner volume 185. The inner volume 185 of the ballast tank 180 can, for example, be in fluid communication with the inner chamber 210 via another opening 215. In other embodiments -forms (not shown) other types of ballast devices such as elastic membranes or other methods for changing the volume or mass of chambers by pumping or activation can be used, as ordinary experts in the field will understand.

Reference is now made to figure 20, where a rigid trunk unit 220 will be described in more detail in connection with embodiments of the present invention. The rigid stem assembly 220 shown in Figure 20 can be used to form at least part of a device towed from an exploration vessel (eg, the exploration vessel 10 of Figures 3-5), including rigid sensor streamers (eg, the rigid sensor streamer 50 in figures 3 and 5) and rigid leads (for example the rigid lead 75 in figures 4 and 5) which are conventionally in the form of flexible cables. Although not shown in Figure 20, embodiments of the rigid stem assembly 220 may include control surfaces (eg, the wings 110a, 110b in Figures 6-13 or the rudder 165 in Figure 18). The rigid stem unit 220 may be a structure for a number of elements, including feed lines, gas lines, optical and/or electrical signals, power, external devices, geophysical sensors, strain sensors, and geophysical sources. The rigid trunk assembly 220 is shown in a disconnected or open condition. When open, the rigid stem assembly 220 may be folded from at least 10° to 180° in a plane between adjacent rigid stems 115. In some embodiments, the rigid stem assembly 220 may be stored on the exploration vessel 10 in the disconnected or open position and assembled prior to deployment in the water body 15.

As shown, the rigid stem assembly 220 may comprise a number of rigid stems 115. The rigid stem assembly 220 (when assembled) is characterized as rigid in that it has a bending, torsional and/or linear stiffness that can be maintained over significant lengths, for example up to about 10 meters, about 50 meters, about 100 meters or even longer. In some embodiments, the rigid stem assembly 220 may have a flexural stiffness of 700 Newton square meters ("Nm<2>") or more over significant lengths (eg, over about 25 meters or more). The rigid stem unit 220 may, for example, have a bending stiffness of 700 Nm<2> over substantially its entire length. Each of the rigid stems 115 may also have a bending stiffness of 700 Nm<2>.

The rigid stems 115 may each comprise a stem body 120. A variety of different materials and composites may be suitable for use in the stem body 120. In some embodiments, the stem body 120 may be made of a material including aluminum, stainless steel, or titanium. In some embodiments, the stem body 120 may be made of a material comprising a composite, such as glass or carbon reinforced plastic, such as glass or carbon fibers in combination with epoxy or other resins (e.g., polyester, vinyl ester, nylon, etc.) . In some embodiments, the glass fibers may include electrically conductive glass fibers, also referred to as "e-glass fibers". In alternative embodiments, suitable e-glass fibers may be boron-free by weight. In some embodiments, the stem body 120 may be made of a material comprising a plastic, such as polyethylene, polybutylene terephthalate, polysulfone, or another suitable thermoplastic polymer. Combinations of suitable materials can also be used. One of ordinary skill in the art who has had the benefit of familiarity with this disclosure should be able to select an appropriate material for stem body 120 based on a number of factors, including selection of appropriate stiffness to weight as well as price and flexural strength of available resins is maintained.

It should be noted that the shape of the cross-section of the rigid stems 115 need not be circular, but may vary as desired for a particular application. The rigid stems 115 can, for example, have an oval, circular, triangular, square, pentagonal, other polygonal, wing-shaped or non-symmetrical cross-section. Figures 21A to 21C illustrate rigid stems 115 having differently shaped cross sections. Figure 21A illustrates a rigid stem 115A having a circular cross-section. Figure 21B illustrates a rigid stem 115B having a triangular cross-sectional shape. Figure 21C illustrates a rigid stem 115C having a flat or wing-shaped cross-section. The wing-shaped cross-section may, for example, be desirable to reduce the drag coefficient of the rigid stem unit 220. A reduced drag coefficient may be particularly beneficial for inlets (for example, the rigid inlet 75 in Figures 4 and 5) where significant cross-flow can be encountered. In some embodiments (not shown), the wing-shaped cross-section may have an asymmetric profile, which may, for example, be beneficial in providing unilateral lift. The wing-shaped cross-section may have a ratio between width W1 and height H1 that is greater than about, and alternatively greater than about 1.5.1 some embodiments, the wing-shaped cross-section may have a ratio between width W1 and height H1 in a range from about 1 to about 10. Figures 21A to 21C further illustrate the rigid trunks 115 which have an inner chamber 245, which may include various cables, such as electrical or optical cables for example.

In some embodiments, stem body 120 may be in the form of a tube or other channel having a tubular portion defining an inner chamber (eg, inner chamber 245 shown in Figures 21A-21C). In some embodiments, a buoyancy material may be used to fill the inner chamber. An example of a suitable filler material includes air or another suitable gas. However, other filler materials may also be used to provide some degree of positive buoyancy for ballast purposes, as well as electrical insulation, including foam, gelled hydrocarbon-based oils, hydrocarbon-based oils, viscoelastic polymer, or other suitable electrically insulating, acoustically transparent materials. In some embodiments, a surface treatment may be applied to the outer surface 225 of the stem body 120, for example to reduce drag and fouling. For example, one or more antifouling agents may be applied to the outer surface 225. As another example, one or more drag-reducing treatments may be applied to the outer surface 225. Although Figure 10 illustrates the rigid, elongated geophysical equipment 105 in the form of a rigid trunk unit comprising three rigid trunks 115, it will be understood that embodiments of the rigid trunk unit 220 may include more or fewer than three rigid trunks 115 as desired for a particular application.

The rigid stems 115 can each have a length in, for example, a range of from about 1.5 meters to about 50 meters or, alternatively, from about 3 meters to about 12.5 meters. In particular embodiments, the rigid trunks 115 can each have a length of about 3.125 meters, about 6.25 meters, about 12.5 meters or about 25 meters. The rigid stems 115 may each have an outer diameter (for example, Di in Figure 21 A) in a range from about 0.02 meters to about 0.2 meters, or in alternative embodiments from about 0.04 meters to about 0.08 meters for embodiments with a circular cross-section. The rigid stems 115 can each have a width (Wi in Figure 21C) in a range of from about 0.1 meter to about 0.5 meter and a height (Hi in Figure 21C) up to about 0.4 meter for embodiments with a wing-shaped cross-section. In some embodiments, the rigid stems 115 may have an aspect ratio (width to height ratio) of, for example, from 1 to about 20, from about 2 to about 20, or from about 1 to about 8. The assembled rigid stem unit 220 may, for example have a length in a range from about 50 meters to about 1000 meters. If more than one rigid trunk unit 220 is connected end to end, the combined unit may have a length in a range from, for example, about 200 meters to about 2000 meters or longer. In some embodiments, the combined unit can, for example, have a length of up to about 16,000 meters or more, which can, for example, be used with towing depths of from a few to several hundred meters.

Reference is still made to figure 20, where embodiments of the rigid stem unit 220 may further comprise end connection elements at each end of the rigid stem unit 220. In the embodiment shown, the rigid stem unit 220 comprises as an end connection element 230 of the male type at one end and an end connection element 235 of the female type at the opposite end. The end coupling elements should be designed for connection to corresponding coupling elements (not shown) provided at the longitudinal ends of adjacent rigid insertion stem units. Each of the end connection elements can make mechanical and electrical contact with corresponding end connection elements on the other rigid stem assemblies (not shown).

As shown in Figure 20, a flexible cable 240, which may for example be an electrical or optical conductor, extends between the rigid stems 115. In some embodiments, the flexible cable 240 may carry a gas, such as air, to maintain air volumes, ballast and recovery, as well as delivery to air guns or other sources that may be on the rigid stem assembly 220. The flexible cable 240 may extend from each end of the rigid stem assembly 220 between the connector elements (for example, from the male connector element 230 to the connector element 235 of the female type). The flexible cable 240 may extend through the inner chamber of the rigid trunks 115. In some embodiments, the flexible cable 240 may, for example, comprise multiple cables extending through the passage.

Reference is now made to figures 22 and 23, where deployment of a rigid stem unit 220 from an exploration vessel 10 will now be described in connection with embodiments of the present invention. For example, one or more rigid trunk units 220 in accordance with embodiments of the present invention can be assembled and deployed from the exploration vessel 10. The one or more rigid trunk units 220 can be used to form at least part of a rigid, extended geophysical equipment towed from an exploration vessel 10, including rigid sensor streamers (for example the sensor streamer 50 in Figures 3 and 5) and rigid leads (for example the rigid lead 75 in Figures 4 and 5) which are conventionally in the form of flexible cables. The stiffness of the rigid stem assembly 220 can be activated upon deployment and then deactivated upon retrieval.

In some embodiments, the rigid trunk unit 220 can be removed from one or more storage bins 250. One of the rigid trunks 115 that make up the rigid trunk unit 220 can, for example, be lifted from the storage bin 250. In some embodiments, the rigid trunks 115, which make up the rigid the stem unit 220, is continuously removed from the storage bins 250 one after the other. As shown in figure 22, the one or more storage bins 250 can be arranged on the exploration vessel 10. The storage bins 250 can for example comprise pallets, reception or other types of rooms for storing the rigid trunk unit 220.1 some embodiments, a rigid trunk unit 220 which comprises a number of disassembled rigid trunks 115, be stored in each of the storage bins 250 on the exploration vessel 10. In some embodiments, the rigid trunk unit 220, in each of the storage bins 250, may comprise at least one flexible cable 240 that extends between the connecting elements (for example the flexible cable 240 extending from the male connector 230 to the female connector 235 in Figure 36). As shown in Figure 20, embodiments of the flexible cable 240 can be rotated about 180° between adjacent rigid stems 115 to minimize storage requirements.

In some embodiments, there may be a device (not shown) for moving the rigid logs 115 from the storage bins 250. For example, the device may lift the rigid logs 115 from the storage bins 250. After being removed from the storage bins 250, the rigid log assembly 220 transported to assembly line 255 for the rigid logs, the purpose of which is to connect the rigid logs 115 to adjacent rigid logs 115 by, for example, using log joints 280. In some embodiments, the log joints 280 may be connected between adjacent rigid logs 115, for example by to slide a sleeve on the rigid stems 115 over and into clamping engagement with the stem joints 280. The assembly line 255 for rigid stems may be manual or at least partially automatic. In some embodiments, one or more individuals may, for example, manually connect the adjacent rigid stems 115 to each other. In alternative embodiments, a device can be used for connecting the adjacent rigid stems 115 to each other.

After connecting the rigid stems 115, the rigid stem assembly 220 can be transported to the destressing apparatus 260. The destressing apparatus 260 holds the rigid stem assembly 220 to remove mechanical stress on the rigid stem assembly 220 caused by the portion of the rigid stem assembly 220 that is deployed in the body of water 15 The unwinding apparatus 260 can be located near the assembly line 255. As shown in Figures 22 and 23, the unwinding apparatus 260 can be arranged on the exploration vessel 10. In some embodiments, the unwinding apparatus 260 can pull the rigid stem unit 220 from the storage bins 250 to the assembly line 255 for the stems. From the assembly line 255, the unwinding apparatus 260 may deploy the rigid stem assembly 220 into the body of water 15. As shown in Figure 22, the rigid stem assembly may bend down as it is deployed into the body of water 15. In alternative embodiments, the rigid stem assembly 220 may bend, for example up, when the level of the water mass 15 is high or if the relaxation device 260 swings. The tensioning device 260 can comprise one or more pairs of wheels that engage with the rigid stem unit 220. In the embodiment shown, the tensioning device 260 comprises three pairs of wheels 265, 270, 275. The tensioning device 260 can apply tensile stress to the rigid stem unit 220 by applying torque to the wheel pairs 265, 270 , 275. In some embodiments, the tensioner 260 may apply more tension per wheel pair 265, 270, or 275, because the rigid stem assembly 220 has a stiffer outer surface than the previously used cables. It should be noted that other types of devices may be used for applying tension to the rigid stem assembly 220. Although not shown, the tension release apparatus 260 may include, for example, clamps that engage shoulders on the rigid stems 115 or grooves or bevels on the rigid trunks 115; clamps in bands or in pistons, or other linear machines which apply force to the rigid stems 115; a hook or other attachment device on a rope connected to an attachment on the rigid stems 115, or studs projecting into holes on the rigid stems 115 and which may be spring-operated.

In some embodiments, more than one rigid stem unit 220 may be assembled and deployed from the exploration vessel 10. To deploy multiple rigid stem units 220, the rigid stem units 220 should be connected end to end. The end connection element at one end of the rigid stem unit 220 should be connected to the corresponding end connection element on the other rigid stem unit 220. In some embodiments, each of the rigid stem units 220 may be stored in separate storage bins 250.

Reference is still made to figures 22 and 23, where an example of a method for retrieving the rigid stem unit 220 on the exploration vessel 10 will now be described. In some embodiments, the detensioning apparatus 260 may pull the rigid stem assembly 220 onto the exploration vessel 15 to retrieve the rigid stem assembly 220. The detensioning apparatus 260 may also hold the rigid stem assembly 220 to remove tension from the rigid stem assembly after the rigid stem assembly 220 is back onboard on the exploration vessel 10. After the destressing apparatus 260, the rigid stem assembly 220 may be transported to the assembly line 255 for disconnection of adjacent rigid stems 115. The assembly line 255 may also function to remove stem joints 280 connecting the adjacent rigid stems 115, where the disconnection may be manual or at least partially automatically. When disassembled, the rigid trunk unit 220 can be placed in one of the storage bins 250. In some embodiments, the rigid trunk unit 220 can be folded as it is placed in the storage bins 250. Figures 22 and 23 illustrate vertical folding of the rigid trunk unit 220. The folding can be carried out under the rear deck, in front of the rear deck or where there is the most available space on the search vessel 10.1 alternative embodiments, the folding can be carried out laterally, for example in a shallow pit, which can utilize a wide rear deck without requiring space on the outside. It should be noted that if multiple rigid trunk units 220 have been deployed, the rigid trunk units 220 may need to be disassembled, for example, to store each rigid trunk unit 220 in a separate one of the storage bins 250 .

A wide variety of techniques can be used in conjunction with embodiments of the present invention to connect adjacent rigid stems 115. Figure 24 illustrates a section of a rigid stem assembly 220, which utilizes a stem joint 280 clamped between the adjacent rigid stems 115 to close the flexible connection by forming a rigid connection between the adjacent rigid stems 115, in accordance with embodiments of the present invention. Two adjacent rigid stems 115 may, as shown, be connected together by means of a stem joint 280 in accordance with embodiments of the present invention. To maintain the rigidity of the rigid stem assembly 220 (for example, as shown in Figure 20), the stem joint 280 may form a rigid connection between adjacent rigid stems 115. As shown, the rigid stems 115 may each have an inner chamber 245 with flexible cables 240 extending between the rigid stems 115, and running through the rigid stems 115 through the inner chamber 245. In accordance with the present embodiments, sleeves 285 may be used to hold the stem joint 280 in a clamped position to connect the rigid stems 115 The end portions 290 of each of the rigid stems 115 may comprise a sleeve 285. The sleeves 285 may be slidably movable on the end portions 290. The sleeves 285 may each be spring-loaded by means of a corresponding spring 295. The outer surface of each of the rigid stems 115, may include a shoulder 300 to receive the corresponding spring 295. The end portions 290 of each of the rigid stems 115, may further include a notch 305 defining a shoulder r 310.

The trunk joint 280 may comprise two clamping portions 315. The clamping portions 315 should cooperate with each other so that when the trunk joint 280 is assembled, the clamping portions 315 define a rigid trunk passage that receives at least a portion of the end portions 290 of the rigid trunks 115. In some embodiments, each of the clamping portions 315 have a C-shaped cross-section. It should be noted that the cross-section of the clamping portions 315 may vary, for example based on the particular design of the rigid stems 115. The clamping portions 315 may each have an inner surface 320, best visible to the upper clamping portion 315. The inner surfaces 320 may each have grooves or recesses at each end which engage corresponding shoulders 310 on the end portions 290 when the trunk joint 280 is assembled. The grooves 325 may each extend around the inner surface 320 at each end of the corresponding clamping portion 315. A clamping shoulder 330 may be defined by each of the grooves 325. The clamping shoulders 330 may engage with the corresponding notches 305 in the end portions 290 when the stem joint 280 is mounted. Each end of the clamping portions 315 may further comprise an outer shoulder 335 for receiving the corresponding sleeve 285. Each of the sleeves 285 slides into the corresponding outer shoulders 335 to secure the clamping portions 315 in a clamping position to connect the rigid stems 115, which shown by means of one of the clamping parts 315 in the lower part of figure 24.

Embodiments of the present invention are not limited to the trunk joint 280 shown in Figure 24. It will be understood that other types of coupling elements can be used to connect the rigid trunks 115. Examples of coupling devices that can be used as the trunk joint 280 include, but is not limited to, a lock nut with an aligned bolt, socket connections, and mating planes orthogonal to the major axis.

Figure 25 illustrates an alternative embodiment for closing the flexible connection between the adjacent rigid stems. As shown, the adjacent rigid stems may be joined together by a stem joint 280 in accordance with embodiments of the present invention. To maintain the rigidity of the rigid stem assembly 220, the stem joint 280 may form a rigid connection between the adjacent rigid stems 115. As shown, the rigid stems 115 may each comprise a stem body 120 having an inner chamber 245 with flexible cables 240 extending between the adjacent rigid stems 115 by means of the inner chamber 245.1 in accordance with the present embodiments, sleeves 285 may be used to hold the stem joint 280 in a clamping position to connect the adjacent rigid stems 115. The stem body 120 on each of the adjacent rigid stems 115, may have a longitudinal end portion 290 above which the sleeves 285 may be arranged. The sleeves 285 may each be slidably movable on the corresponding longitudinal end portion 290 to cover the trunk joint 280 and hold it in place. Although not shown, a locking element may be provided to secure the sleeves 285 in the locking position. The sleeves 285 can, for example, each be spring-loaded by means of a corresponding spring.

The trunk joint 280 may include two clamping portions 315. The clamping portions 315 should cooperate with each other such that, when the trunk joint 280 is assembled, the clamping portions 315 define a rigid trunk passage that receives at least a portion of the longitudinal end portion 290 of each of the adjacent rigid trunks 115. In some embodiments, each of the tension portions 315 may generally have a bent or C-shaped cross-section. It should be noted that the cross-section of the clamping portions 315 may vary, for example, based on the particular design of the adjacent rigid stems 115. The clamping portions 315 may each have an inner surface 320. The inner surfaces 320 may each have axially projecting grooves or recesses 340 to receive the end portions 290 of the adjacent rigid stems 115. As shown, the clamping portions 315 may have holes 345 for receiving bolts (not shown) to hold the clamping portions 315 in place. In some embodiments, the sleeves 285 may also slide over the ends of the tension portions 315 to secure the tension portions 315 in a clamped position to connect the adjacent rigid stems 115. In other embodiments (not shown), the tension portions 315 may pass over not only the flexible cables 240, but also hinges or another mechanism that can connect the rigid trunks 115 while a flexibility axis is kept open for folding of the trunks to be closed by the tension parts 315.

Figures 24 and 25 illustrate an alternative embodiment for closing the flexible connection between the adjacent rigid stems 115. In the embodiment shown, a section of a rigid stem unit 220 comprising two adjacent rigid stems 115 is shown. As shown in Figure 26, they can adjacent rigid trunks 115 are held together by means of two hinges 350 in the open state. The hinges 350 can generally form a flexible connection between the adjacent rigid trunks 115. The hinges 350 can generally enable folding up to 180° in one plane, so that the rigid trunk unit 220 can be stored on the exploration vessel 10 when it is not in use. Other designs for the hinges 350 may be used in accordance with embodiments of the present invention. Although not shown, electrical or optical conductors may also extend between the adjacent rigid stems 115.

Figure 27 illustrates the flexible connection between the rigid stems 115 in a closed position. In the illustrated embodiment, a locking pin 355 may be used to secure the flexible connection between the rigid stems 115 and stiffen the connection between them. Each of the rigid stems 115 can, as shown, have an arm 365 which extends longitudinally from them. Openings 360 at the end of each arm 365 may be provided with the locking pin 355 arranged through the provided openings 360 to close the flexible connection. Although Figures 26 and 27 illustrate the use of hinges 350 to form the flexible connection, other suitable techniques such as the flexible cable 240 (eg Figure 20) may be used to form the flexible connection with the locking tab 440 used to close the flexible the connection. Figures 28 and 29 illustrate another alternative embodiment for closing the flexible connection between the adjacent rigid stems 115. In the embodiment shown, a section of a rigid stem unit 220 comprising two adjacent rigid stems 115 is illustrated. As shown in Figure 28, they can the rigid trunks 115 are held together by means of a flexible cable 240 in the open position. The flexible cable 240 may generally form a flexible connection between the adjacent rigid stems 115, for example to allow folding of the rigid stem assembly 220 for storage when not in use. Figure 29 illustrates the flexible connection between the rigid stems 115 in a closed state. In the illustrated embodiment, one of the rigid stems 115 includes a base 370 while the other of the rigid stems 115 includes an extendable member, such as an extendable rod 375. The extendable rod 375 may be arranged to extend into the base. 370 to close the flexible connection and stiffen the connection between the adjacent rigid rods 115. The bending stiffness of the extendable rod 375 can be used to stiffen the connection and prevent bending. Although Figures 28 and 29 illustrate use of the flexible cable 240 to form the flexible connection, other suitable techniques such as the hinges 350 (eg, as in Figure 26) may be used to form the flexible connection with the retractable rod 375 and the base which is used to close the flexible connection. Figures 30 and 31 illustrate another alternative embodiment for closing the flexible connection between the adjacent rigid stems 115. In the embodiment shown, a section of a rigid stem unit 220 comprising two adjacent rigid stems 115 is illustrated. As shown in Figure 30, they can adjacent rigid stems 115 are held together by means of hinges 350 in the open condition. The hinges 350 may generally form a flexible connection between the adjacent rigid stems 115, for example to allow folding of the rigid stem assembly 220 for storage when not in use. Figure 31 illustrates the flexible connection between the rigid stems 115 in a closed state. In the illustrated embodiment, one of the rigid stems 115 includes a base 370 which can be threaded, for example. The opposite of the rigid stems 115 may include an extensible member, such as a threaded rod 375. The threaded rod 375 may be rotated into threaded engagement with the socket 370 to form the flexible connection and thereby stiffen the connection to prevent bending. Figures 30 and 31 also show a stop formed by intersecting extensions 390 from each rigid stem 115, to further enable a rigid connection, for example where the threaded rod 375 may only be under tension. Although Figures 30 and 31 illustrate the use of hinges 350 to form the flexible connection, other suitable techniques such as the flexible cable 240 (eg Figure 20 or Figure 28) may be used to form the flexible connection with the threaded rod 375 and the socket 370 used to close the flexible connection.

Figures 32 and 33 illustrate an exemplary embodiment that includes a protective cover 395. As shown, the protective cover 395 may be applied between the adjacent rigid stems 115 to protect the flexible connection, such as electrical conductors, optical conductors and other cables, parts and supply lines that may be located there. The protective cover 395 may extend over the flexible connection in the closed condition, best seen in Figure 33. In some embodiments, the protective cover 395 may be disposed on one of the rigid stems 115 (Figure 30) and slide over the flexible connection for protection (figure 31). The protective cover 395 can be locked with engaging threads (not shown) directly onto the rigid stems 115, fit snugly against one or more cylindrical surfaces (not shown) on either side of the rigid stems 115, or fit together in other ways that will be obvious to ordinary experts in the field who have been able to familiarize themselves with this description. The protective cover 395 can be placed over the flexible connection manually or with a machine. In other embodiments, the protective cover 395 may be held together with locking tabs, nuts, or other suitable connecting mechanism. Although Figures 32 and 33 illustrate the use of hinges 350 to form the flexible connection and a locking tab 335 to close the flexible connection, other suitable techniques such as those described herein may be used in connection with embodiments of the present invention.

As shown in Figures 34 and 35, the protective cover 395 may also be used in some embodiments to close the flexible connection, thereby stiffening the connection and preventing bending. A flexible cable 240 may be used to hold the adjacent rigid stems 115 together in the open condition, as best seen in Figure 34. To close the flexible connection, the protective cover 395 may be attached between the adjacent rigid stems 115. Although Figures 34 and 35 illustrate use of the flexible cable 240 to form the flexible connection, other suitable techniques such as the hinges 350 (see, for example, Figures 26, 30 or 32) may be used to form the flexible connection with the protective cover 395 used to close the flexible connection.

As previously mentioned, embodiments may include two or more rigid stem units 220 joined end to end to form a rigid streamer (eg Figures 3 and 5) or a rigid insert 75 (eg Figure 4). Although a number of different techniques can be used to connect the rigid stem units 220 to each other, coupling members can be used at each end of the streamer units for connection. Figures 36 and 37 illustrate end connector elements that can be used in accordance with embodiments of the present invention for connecting rigid trunk units 220. As shown, a male type connector element 230 can be used, which includes a base portion 400 and an extension 405 from the base portion 400. The connector element 115 of The male type may further include conductors 410, such as electrical and optical conductors, in an inner portion 415 of the connector 230. The extension 405 may include electrical contacts 420. A female connector 235 may also be used, which includes a socket 425. An inner portion 430 of the coupling element 235 may also include conductors 435, such as electrical and optical conductors. The socket 425 can, for example, also include electrical conductors 440. As can best be seen in Figure 37, the extension 405 of the male-type coupling element 235 can be occupied in the socket 425 of the female-type coupling element 235. Electrical and/or optical connection can be established between the connection elements 230, 235, for example by using the electrical contacts 520, 540 in the extension 405 and the base 425.

Although the foregoing discussion describes the use of rigid extended geophysical equipment comprising a number of interconnected rigid stems 115 to form the rigid geophysical equipment having control surfaces, other suitable techniques may be used to form the rigid extended geophysical equipment that may be used in embodiments of the present invention. Figures 38 and 39 illustrate sketches of an equipment segment 500 which has variable stiffness and which can be used in the formation of rigid, extended geophysical equipment. In some embodiments, a number of equipment segments 500 may be connected end-to-end to form the rigid, elongated geophysical equipment. Figure 38 illustrates the equipment segment 500 in a state that can be stored. Figure 39 illustrates the equipment segment 500 in an operational state where the streamer has increased stiffness, such as bending, linear and/or torsional stiffness. The equipment segments 500 may be a construction for a number of elements, including feed lines, gas lines, optical and/or electrical signals, power, external devices, geophysical sensors, strain sensors and geophysical sources. Control surfaces, such as those previously discussed, may be incorporated into the equipment segments 500. The equipment segment 500 may have a length in a range of, for example, from about 10 meters to about 100 meters. Depending on the particular application, the rigid, elongated geophysical equipment formed by the equipment segments 500 may, for example, have a length ranging from about 200 meters to about 2000 meters or more.

In some embodiments, the equipment segment 500 may have a proximal (that is, closest to the exploration vessel 10) end 505 and a distal (that is, farthest from the exploration vessel 10) end 510. 1 the embodiment shown, the equipment segment 500 includes a sheath 515, spacers 520, tension members 525 and a stretch activator 530. The jacket 515 may generally function as an outer cover that at least partially covers and protects the internal components of the equipment segment 500 from water ingress. In some embodiments, the sheath 515 may for example be made of a flexible, acoustically transparent material, such as polyurethane. One or more plates may be located at or near the axial end of the sheath 515. For example, a proximal plate 535 may be located at or near the proximal end 505, and a distal plate 540 may be located at or near the distal end 510.

In some embodiments, the tension members 525 may extend substantially the entire length of the equipment segment 500. The tension members 525 may generally function to provide the equipment segment 500 with the ability to carry axial mechanical load. The tension members 525 can, for example, transmit axial load along the length of the equipment segment 500. In some embodiments, the tension members 525 can be made of metal, such as stainless steel or plastic materials with high tensile strength. The tensioning means 85 can be in the form of a cable or a fiber rope, for example. At the proximal end 505, the tension members 525 may extend proximally over the proximal plate 525. The tension members 525 may also extend proximally over an activator plate 540 located at the proximal end 505. As shown, the tension members 525 may extend from the proximal end 505 extend through the activator plate 505, through the proximal plate 525 and through the spacers 520 to the distal end 510. At the distal end 510, the tension members 525 may extend through the distal plate 540. In accordance with the present embodiments, the tension members 525 may move translationally relative to to the activator plate 540, the proximal plate 525, the spacers 520, and the distal plate 540.1 the storable condition of the equipment segment 500, for example, the tension members 525 may be allowed to slide in the spacers 520. Nuts (such as the axial nuts 545 and the distal nuts 550) or other suitable mechanical stops may be located at each axial end of the tension members 525. As shown, the axial end of the tension members 525 can be spring-loaded with springs 555 arranged on the tension members 525 between the distal nuts 550 and the distal plate 540. The springs 555 can be compressed when tension is applied to the tension members 525 show the tension activator 530.

The equipment segment 500 can, as shown further, comprise a number of spacers 520 arranged along the length of the jacket 515. In accordance with the present invention, the spacers 520 can be so tightly packed that when the tension activator 530 applies tension to the tension members 525, the spacers 520 can be pressed together to align the spacers 520 in a straight line. The spacers 520 may be made of a foam material to, for example, provide buoyancy. The spacers 520 can, for example, include a foam material which fills voids, and which comprises a polyurethane foam or another suitable material. As shown, a large volume of the equipment segment 500 may be occupied by the spacers 520. At least about 50% of the interior volume and as much as 90% or more of the interior volume of the equipment segment 500 and/or the streamer 40 may be occupied by the spacers 520. Oil or other suitable filler material occupies the internal volume of the equipment segment 500. However, because a large volume of the equipment segment 500 may be occupied by the spacers 520, less oil or other filler materials can be used to thereby minimize potential problems caused by leakage . Furthermore, foam materials such as rigid foams cannot handle pressures of more than a few meters while also providing more than 4 times more buoyancy than certain other filler materials, such as oils. The interior of the spacers 520 can also be designed with closed, hollow spaces, so that a leak in the jacket 515 will not necessarily fill the entire volume.

In some embodiments, the spacers 520 may each have a protective outer cover layer or an outer protective skin 560. The outer cover layer 560 may generally function as an outer cover that protects the internal components of the spacers 520 from water ingress, for example. In some embodiments, the outer cover layer 560 may be made of a flexible, acoustically transparent material, such as polyurethane. In some embodiments, the outer cover layer 560 may have a thickness in a range from about 0.5 mm to about 5 mm. In a particular embodiment, the outer cover layer 560 can have a thickness of about 1 mm. As shown, the spacer 520 can further have channels 565 for the stretching members 525. In the shown embodiment, the stretching members 525 extend through the channels 565. As previously mentioned, the stretching members 525 can be allowed to move freely in the channels 565. The spacers 520 can, as also shown, further include a compression means, such as a central core 570. In the illustrated embodiment, the central core 570 is disposed in the center of the spacer 520 and has outer surfaces on each axial end of the spacer 520. The outer surfaces of the central core 570 may be in contact with adjacent outer surfaces of adjacent spacers 520 when compressed in the operative condition. The central core 570 may comprise a material capable of withstanding the high axial loads that may be applied to the spacer

520 in the operational state. Voids in the spacer 520 may be filled with a foam material 575, which may comprise a foamed polyurethane or other suitable foam. Although not shown, spacer 520 may further include conduits for conductor cables and cavities for geophysical sensors, transducers, and other equipment used in geophysical data collection. Modifications can be made to the spacers 520 shown in Figures 38 and 39 to accommodate these additional components. For example, additional channels may be required through the spacer 520 for conductor cables, while additional cavities may be required for the incorporation of other components. Openings to pressure-sensitive areas (for example, the outer cover 565) may additionally be necessary for geophysical sensors such as hydrophones to sense pressure signals in the water. Embodiments (not shown)

may also replace the central core 570 with a structure that provides a sealed and depressurized space inside. In some embodiments, this structure may be an eggshell-shaped or a cylindrical-shaped structure. However, other suitable configurations for the structure can also be imagined.

In some embodiments, the tension activator 530 may be located at the proximal end 505 of the equipment segment 500. The tension activator 530 may generally be designed to apply tension other than towing tension to the tension members 525. As shown, the tension activator 530 may be coupled to the activator plate 540. The tension activator 530 may have the activator plate 540 to move axially towards and into engagement with the proximal bolts 545 or another mechanical abutment on the tension members 525. The activator plate 540 transfers mechanical force from the tension activator 530 to the tension members 525. An example of a suitable tension activator 530 is a linear drive unit which generates movement in a straight line to move the actuator plate 540. Other suitable actuated drives may also be used to apply voltage to the tension members 525 in accordance with embodiments of the present invention.

In accordance with the present embodiments, the equipment segment 500 may have variable stiffness. The equipment segment 500 can, for example, have a storable design where the streamer can be deployed and stored on a drum on board an exploration vessel (for example the exploration vessel 10 in Figure 3). Figure 38 illustrates the equipment segment 500 in the storable state. In the storable state, the tension members 525 may be allowed to slide relative to the spacers 520. The spacers 520 may be packed tightly in the equipment segment 500, but have enough space between them to allow the equipment segment 500 to bend. As can best be seen in Figure 38, the equipment segment 500 can be freely bent in the storable state, for example for winding on a drum. At a desired time, the equipment segment 500 can be placed in the operative state where the equipment segment 500 has increased stiffness. In the operational state, the equipment segment 500 is characterized as rigid in that it has a bending, torsional and/or linear stiffness that can be maintained over significant lengths, for example up to about 10 meters, about 50 meters, about 100 meters or even longer when assembled end to end with other streamer segments 60 in the operational state. In some embodiments, the equipment segment 500 in the operational state may have a bending stiffness of 700 Nm<2> or more. In some embodiments, the spacers 520 may be so tightly packed that when the tension activator 530 applies tension to the tension members 525, the spacers 520 may be compressed to align the spacers 520 in a rigid line, increasing the bending stiffness of the equipment segment 500. The spacers 520 in compression and the tension members 525 in compression, should contribute to the flexural stiffness of the equipment segment 500.

In the illustrated embodiment, the tension activator 530 may be used to apply tension to the tension members 525 to place the equipment segment 500 in the operative condition. The tension activator 530 can cause the activator plate 540 to move axially outwardly in engagement with the proximal bolts 545 or other mechanical abutments on the tension members 525. In this way, the activator plate 540 transfers mechanical force from the tension activator 530 to the tension members 525 to cause the tension members to move axially . As the tensioners 525 move, the distal nuts 550 of the tensioners 85 contact the distal plate 540 and cause the distal plate 540 to apply force to the spacers 520 to compress the spacers 520 between the distal plate 540 and the axial plate 95. Compression of the spacers 520 aligns the spacers 520 in a rigid line. Other suitable techniques for placing the spacers 520 in a straight line can also be used in connection with embodiments of the present invention.

In contrast to systems that utilize rigid, extended geophysical equipment comprising a number of interconnected rigid stems during a marine survey, Figure 40 illustrates a conventional seismic survey system 600. As shown, the seismic survey system 600 may include an exploration vessel 605 towing a number of sensor streamers 610 through a body of water 615. Insertion lines 620 may be used to connect the sensor streamers 610 to the exploration vessel 605. Each of the sensor streamers 610 may include sensors 625. The sensor streamers 605 may also include lateral force and depth control devices (LFD devices) 630 (e.g., vanes). and associated acoustic position determination devices 635, which can be arranged at selected positions along the sensor streamers 605 co-located with the LDF devices 630 or at separate positions. Spreading devices 640, such as limbs or paravanes may be used to maintain lateral separation of the sensor streamers 605. In contrast to the system illustrated in Figure 29, embodiments of the present invention that utilize rigid stem assemblies during a survey may contain almost no bends , limbs, paravanes, chains or extra rope, or LFD devices, such as wings. For example, a seismic survey can be carried out that only has the desired lights and antennas above the water.

The present invention is therefore suitable for achieving the purposes and advantages mentioned, as well as those inherent in the origin. The particular embodiments discussed above are only illustrative as the present invention can be modified and practiced in different but equivalent ways which will be obvious to those skilled in the art who have been able to familiarize themselves with what is described here. Although individual embodiments are discussed, the invention covers all combinations of all these embodiments. No limitations are further intended in connection with the construction details or designs shown here, other than what is described in the following claims. It is therefore obvious that the particularly illustrative embodiments described above can be changed or modified, and all such variations are intended to be within the scope of the present invention. All figures and ranges described above may vary to some extent. Whenever a numerical range with a lower limit and an upper limit is indicated, it is intended that any number and any included range falling within that range are specifically described. The indefinite articles "a" or "an" as used in the patent claims are here determined to mean one or more than one of the elements introduced by the article. The expressions in the claims also have their pure, ordinary meaning, unless otherwise explicitly and clearly defined by the patent applicant. If there is any conflict in the use of words or expressions in this specification and one or more patents or documents that may be incorporated herein by reference, the definitions that are consistent with the dp specification shall be used understood

Claims (27)

1. Apparatus for use in a marine geophysical survey, comprising: rigid, extended geophysical equipment having a ratio of length to a greatest dimension of width or height of about 1000:1 or more, wherein the rigid, extended geophysical equipment includes control surfaces for regulating the motion of the rigid, elongated geophysical equipment as it is towed through a body of water. 2. Device according to claim 1, wherein the rigid, extended geophysical equipment is operative as at least one of: an inlet connecting a streamer to an exploration vessel, a streamer carrying a sensor or a source cable for towing a geophysical source. 3. Device according to claim 1, where the rigid geophysical equipment comprises a number of rigid stems which are connected to each other and each of which comprises a stem body which defines one or more internal chambers, and where the control surfaces comprise a wing mounted to the stem body. 4. Device according to claim 1, where the rigid, extended geophysical equipment comprises an equipment section comprising an outer jacket and a number of spacers arranged in the outer jacket, where the spacers are designed to be aligned on a rigid line. 5. Device according to claim 1, where the control surfaces comprise at least one surface selected from the group consisting of a wing, a balancer and a rudder. 6. Device according to claim 1, where the control surfaces comprise wings mounted on the rigid, extended geophysical equipment. 7. Device according to claim 6, where each of the wings can be stored in a corresponding wing cavity in the rigid, extended geophysical equipment, as each of the wings can be extended from the corresponding wing cavity. 8. Device according to claim 7, where the rigid, extended geophysical equipment comprises sleeves that cover each wing cavity, the sleeves being slidably movable on the rigid, extended geophysical equipment. 9. Device according to claim 8, where one or more of the wings are designed to slide to different positions in the wing cavity to adjust control of wing angle, where the wing cavity is in the form of an angled groove. 10. Device according to claim 1, where the rigid, extended geophysical equipment has a maximum width of about 100 millimeters, a maximum height of about 100 millimeters and a length of about 100 meters or more. 11. Device according to claim 10, where the rigid, extended geophysical equipment has a length of from about 200 meters to about 16,000 meters. 12. Device according to claim 1, where the rigid, extended geophysical equipment has an operational configuration with a bending stiffness of 700 Nm<2> or more over a distance of at least 25 meters. 13. Marine survey system, comprising: a survey vessel; and rigid, extended geophysical equipment adapted to be towed from the exploration vessel, wherein the rigid, extended geophysical equipment has a length of from about 200 meters to about 16,000 meters and a ratio of length to a greatest dimension of width or height of about 1000:1 or more, and where the rigid, extended geophysical equipment includes control surfaces for controlling movement of the rigid, extended geophysical equipment when towed from the exploration vessel. 14. System according to claim 13, wherein the rigid, extended geophysical equipment is operative by at least one of: an inlet connecting the streamer to the exploration vessel, a streamer carrying a sensor or a source cable for towing a geophysical source. 15. System according to claim 13, where the rigid geophysical equipment comprises a number of rigid stems which are connected to each other and each of which comprises a stem body which defines one or more internal chambers, and where the control surfaces comprise a wing mounted to the stem body. 16. System according to claim 13, wherein the rigid, extended geophysical equipment comprises an equipment section comprising an outer jacket and a number of spacers arranged in the outer jacket, where the spacers are arranged to be aligned on a rigid line. 17. System according to claim 13, where the control surfaces comprise wings mounted to the rigid, extended geophysical equipment. 18. System according to claim 17, where each of the wings can be stored in a corresponding wing cavity in the rigid, extended geophysical equipment, each of the wings being arranged to be able to be extended from the corresponding wing cavity. 19. System according to claim 17, where the rigid, extended geophysical equipment has a maximum width of about 100 millimeters and a maximum height of about 100 millimeters. 20. System according to claim 17, where the rigid, extended geophysical equipment has an operational design with a bending stiffness of 700 Nm<2> or more over a length of at least 25 meters. 21. Method for geophysical surveys, comprising: towing a rigid, extended geophysical equipment from an exploration vessel in a body of water, wherein the rigid, extended geophysical equipment has a ratio of length to greatest dimension of width or height of about 1000:1 or more; controlling the movement of the rigid extended geophysical equipment using one or more control surfaces on the rigid extended geophysical equipment; and either (1) detecting a geophysical signal with a sensor towed by the exploration vessel, and/or (2) activating a geophysical source being towed by the exploration vessel. 22. Method according to claim 21, further comprising connecting a number of rigid stems end to end to form the rigid, extended geophysical equipment. 23. Method according to claim 21, further comprising aligning a number of spacers in the rigid, extended geophysical equipment on a rigid line. 24. Method according to claim 21, where the control surfaces comprise vanes, the method further comprising placing the vanes to selectively position the rigid, extended geophysical equipment in the body of water. 25. Method according to claim 24, where the placement comprises opening sleeves on the rigid, extended geophysical equipment. 26. Method according to claim 21, further comprising adjusting the vane angle of a vane on the rigid, extended geophysical equipment by positioning the vane in an angled slot in the rigid, extended geophysical equipment. 27. Method according to claim 21, wherein the rigid, extended geophysical equipment functions as at least one of: an inlet connecting a streamer to the exploration vessel, a streamer to a sensor or a source cable for towing the geophysical source.