SYSTEM AND METHOD FOR USING AUTONOMOUS UNDERWATER VEHICLES OPERATED FROM SURFACE PLATFORMS FOR OCEAN BOTTOM SEISMIC NODES

Abstract

A system and method for deploying and retrieving a plurality of ocean bottom seismic nodes to and from the seabed by using a floating platform. The system comprises an autonomous underwater vehicle (AUV) coupled to a node skid that is configured to handle a plurality of ocean bottom seismic nodes. The AUV and coupled skid may be lowered to and raised from the seabed and a platform in a garage. The AUV may comprise one or more fuel cells in addition to or as a replacement of traditional rechargeable batteries. The system may utilize an unmanned underwater vehicle (UUV) or unmanned surface vehicle (USV) to monitor and track AUV deployment and to provide acoustic communications between the surface platform and the AUV.

Claims

1. A subsea system for the subsea transfer of a plurality of ocean bottom seismic nodes, comprising: an autonomous underwater vehicle (AUV) comprising a power source and a propulsion system, wherein the power source comprises a plurality of rechargeable batteries and one or more hydrogen fuel cells.

2. The system of claim 1, wherein the power source is configured to switch between the fuel cells and the rechargeable batteries during subsea travel.

3. The system of claim 1, wherein the hydrogen fuel cells are configured for a primary power source and the rechargeable battery cells are configured for a secondary power source.

4. The system of claim 1, further comprising one or more pressure chambers comprising pressurized hydrogen (H.sub.2) and pressurized oxygen (O.sub.2).

5. The system of claim 1, further comprising an AUV garage configured to be raised to and lowered from a surface platform and the seabed, wherein the AUV garage is configured to hold the AUV.

6. The system of claim 1, further comprising a skid configured to be removably attached to the AUV, wherein the skid is configured to hold a plurality of ocean bottom seismic nodes, wherein the skid comprises a variable buoyancy system (VBS).

7. The system of claim 6, wherein the VBS comprises a plurality of pipes and a positive displacement pump, wherein the VBS is configured to control a buoyancy of the skid based on a payload of the skid.

8. An autonomous underwater vehicle (AUV) for the subsea transfer of a plurality of ocean bottom seismic nodes, comprising a power source comprises a plurality of rechargeable batteries and one or more hydrogen fuel cells; and a propulsion system configured to propel and steer the AUV while travelling underwater, wherein the propulsion system comprises a plurality of thrusters, wherein the AUV is configured to hold a plurality of ocean bottom seismic nodes, wherein the AUV is configured to move each of the plurality of ocean bottom seismic nodes to and from the seabed by a manipulator arm.

9. A method for the deployment of a plurality of ocean bottom seismic nodes on or near the seabed, comprising deploying an autonomous underwater vehicle (AUV) from a surface platform, wherein the AUV comprises a power source that comprises a plurality of rechargeable batteries and one or more hydrogen fuel cells; deploying an unmanned surface vehicle (USV) from the surface platform to assist communications from the AUV to the surface platform; and automatically deploying the plurality of ocean bottom seismic nodes at a pre-plot position for each of the plurality of ocean bottom seismic nodes.

10. The method of claim 9, further comprising switching a power supply for the AUV between the plurality of rechargeable batteries and the one or more hydrogen fuel cells.

11. The method of claim 9, wherein the AUV is coupled to a node skid comprising the plurality of ocean bottom seismic nodes.

12. A system for the deployment of a plurality of ocean bottom seismic nodes from the seabed, comprising: a surface platform; one or more autonomous underwater vehicles (AUVs); one or more unmanned surface vehicle (USVs); and a plurality of ocean bottom seismic nodes.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The following drawings form part of the present specification and are included to further demonstrate certain aspects of the present invention. The invention may be better understood by reference to one or more of these drawings in combination with the detailed description of specific embodiments presented herein.

[0010] FIGS. 1A-1D illustrate one embodiment of an autonomous underwater vehicle (AUV) for the handling of ocean bottom seismic nodes according to one embodiment of the present disclosure.

[0011] FIGS. 2A-2C illustrate one embodiment of an AUV coupled to a node skid that can be positioned within a garage or basket, according to one embodiment of the present disclosure.

[0012] FIGS. 3A-3C illustrate one embodiment of handling an AUV and the associated garage on the back deck of a marine vessel according to one embodiment of the present disclosure.

[0013] FIGS. 4A-4B illustrate one embodiment of deploying an AUV from a back deck of a marine vessel according to one embodiment of the present disclosure.

DETAILED DESCRIPTION

[0014] Various features and advantageous details are explained more fully with reference to the non-limiting embodiments that are illustrated in the accompanying drawings and detailed in the following description. Descriptions of well-known starting materials, processing techniques, components, and equipment are omitted so as not to unnecessarily obscure the invention in detail. It should be understood, however, that the detailed description and the specific examples, while indicating embodiments of the invention, are given by way of illustration only, and not by way of limitation. Various substitutions, modifications, additions, and/or rearrangements within the spirit and/or scope of the underlying inventive concept will become apparent to those skilled in the art from this disclosure. The following detailed description does not limit the invention.

[0015] Reference throughout the specification to one embodiment or an embodiment means that a particular feature, structure, or characteristic described in connection with an embodiment is included in at least one embodiment of the subject matter disclosed. Thus, the appearance of the phrases in one embodiment or in an embodiment in various places throughout the specification is not necessarily referring to the same embodiment. Further, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

Overview

[0016] In one embodiment, the disclosed system deploys ocean bottom seismic nodes, and the related equipment, from a surface platform instead of a surface vessel as is typically done in the prior art. The surface platform may be a surface producing oil and gas structure or a simple platform. The surface platform may be a floating storage and offloading unit (FSO), a floating production storage and offloading unit (FPSO), a semi sub, or in shallower water a jack up rig. In some embodiments, the surface platform may be any surface platform and is not limited to oil and gas platforms. The disclosed embodiment may save up to $100,000 per day for seismic operations.

[0017] In one embodiment, all of the deployment and retrieval equipment is transported out to the field on a platform supply vessel (PSV) and positioned on the floating platform via crane. In one embodiment, one or more AUVs, skids, seismic nodes, AUV garage, node handling equipment, and LARS units are moved to and installed on the platform. The units may be installed over the moon pool or outboard side using a twist lock fastening pre-arranged onboard. In one embodiment, the seismic nodes and other equipment many be stored in storage containers and transported to the platform in such containers. The node storage and service system is configured to handle, store, and service the nodes before and after the deployment and retrieval operations performed by a node deployment system. Such a node storage and service system is described in more detail in U.S. Pat. No. 9,459,366, incorporated herein by reference. The equipment used may be classed for Zone 2 operations and designed according to codes for offshore modules installed on offshore platforms. Should an explosive risk increase to Zone 1 or higher, power is cut to the seismic node spread; such an operation is feasible as the seismic node operations are non-critical to surface platform operation.

[0018] In one or more embodiments, an autonomous underwater vehicle (AUV) is used to deploy or retrieve seismic nodes from the ocean bottom. An AUV in the following description is considered to encompass an autonomous self-propelled underwater vehicle. In general, the structure and operation of a seismic AUV is well known to those of ordinary skill. For example, Applicant's U.S. Pat. No. 9,090,319, incorporated herein by reference, discloses one type of autonomous underwater vehicle for marine seismic surveys. Other AUVs are also known, such as U.S. Pat. No. 9,891,333, incorporated herein by reference. An AUV may or may not incorporate seismic sensors. A HAUV may be considered as a hovering autonomous underwater vehicle and may be equivalently referred to as an unmanned underwater vehicle (UUV). For the purposes herein, the terms AUV and HAUV are used interchangeably. As disclosed herein, the AUV (which may refer to as a UUV or a HAUV) does not require an electrical connection for power or communications to a surface vessel. The AUV may contain its own power source (e.g., batteries). The AUV is autonomous in that it is pre-programmed to execute a series of subsea tasks.

[0019] In one embodiment, the deployed AUV (loaded with seismic nodes) has a range of approximately 25 km, so it needs to operate within a 50 km diameter from the surface platform. In one embodiment, the AUV when sufficient nodes have been deployed from the surface platform, a standard marine source vessel can arrive and commence shooting over the lines of deployed nodes. When the shooting phase is near completed, the AUVs can be deployed to retrieve the seismic nodes in conventional retrieval techniques.

[0020] In one embodiment, data is recovered directly to the surface platform from the seismic nodes. Fast track processing could be carried out onboard to facilitate rapid decision making or data can be transported onshore for processing and interpretation. Due to the high data bandwidth on majority of surface platforms, remote operations for seismic node deployment and retrieval operations is feasible. The flexible operating nature of this approach may provide a tool for reservoir geologists onboard the surface platform to gather data in specific locations on more regular basis, for example higher resolution imaging around oil and injected water fronts. In one embodiment, installation, commissioning, and maintenance teams are still required on the offshore platform, but can become a shared resources over several surface platforms on large fields with multiple surface platforms equipped with the disclosed seismic deployment and retrieval units and equipment.

[0021] In one embodiment, the AUV uses one or more hydrogen fuel cells in addition to or as a replacement of the traditional rechargeable battery cells. The use of hydrogen fuel cells can extend the AUV's range from 25 km to approximately 50 km or more. Any hydrogen (H.sub.2) or oxygen (O.sub.2) can be replaced onboard the surface platform and be replenished with additional supply runs by the PSV. In one embodiment, the AUV is configured to have its power supply reconfigured from a conventional battery source to a hydrogen fuel cell power source by swapping out specific modules in the AUV, which can be done on the surface platform or subsea operations. The AUV may have a variable buoyancy system (VBS) with one or more titanium tanks designed for high pressure situations; one or more of these tanks may repurposed for hydrogen and oxygen storage for the hydrogen fuel cell power source.

[0022] In one embodiment, the AUV has highly accurate DVL/IMU onboard. The AUV can swim out to start the planned subsea mission and position itself near the water surface (approximately 30 m or less from the surface) to correct for DVL/IMU drift using DGPS position. After correcting for its GPS position, the AUV can then dive to its first node position for deployment (or retrieval). In one embodiment, the disclosed system and method utilizes a Long Base Line (LBL) approach for subsea positioning (that may already be in place) or could potentially deploy its own LBL array in advance of the node deployment. SBL or USBL positing could be used either from a surface support vessel following the sub or an Unmanned Surface Vessel (USV) that could also be deployed form the surface platform or sent out from a shore base as an independent vessel.

[0023] An autonomous seismic node is well known in the art. The disclosed AUV and deployment and retrieval methods disclosed herein does not necessarily depend on a particular design or configuration of a seismic node. In general, autonomous ocean bottom nodes are independent seismometers, and in a typical application they are self-contained units comprising a housing, frame, skeleton, or shell that includes various internal components such as geophone and hydrophone sensors, a data recording unit, a reference clock for time synchronization, and a power source. The power sources are typically battery-powered, and in some instances the batteries are rechargeable. In operation, the nodes remain on the seafloor for an extended period of time. Once the data recorders are retrieved, the data is downloaded and batteries may be replaced or recharged in preparation of the next deployment. Various designs of ocean bottom autonomous seismic nodes are well known in the art. Autonomous nodes include spherical shaped nodes, cylindrical shaped nodes, disk shaped nodes, and square shaped nodes. Some of these devices and related methods are described in more detail in the following patents, incorporated herein by reference: U.S. Pat. Nos. 6,024,344; 7,310,287; 7,675,821; 7,646,670; 7,883,292; 8,427,900; 8,675,446; and 9,523,780. In one embodiment, the seismic nodes utilized by the disclosed AUV are Applicant's MANTA nodes, which may be substantially similar to the seismic node described in U.S. Pat. Nos. 9,494,700 and 9,523,780, which are incorporated herein by reference in their entirety.

[0024] In another embodiment, the disclosed AUVs are deployed and retrieved from a back deck of a marine vessel. Such marine vessels and back decks are well known to those in the art. The back deck may comprise a plurality of containerized shipping containers that holds the seismic nodes, skid deck loader units, servers, and other necessary equipment on the back deck of the marine vessel, as disclosed in U.S. Pat. Nos. 9,784,873 and 9,459,366, incorporated herein by reference. The back deck of the vessel may comprise conventional LARS unit for the deployment of ROVs, AUVs, and baskets to the seabed. A plurality of AUVs and subsea garages may be placed on the surface of the vessel during deployment and retrieval operations. In one embodiment, when the garage is landed on the back deck, it fully interfaces with the containerized deployment system for handling of the AUVs, autonomous seismic nodes, and/or coupled skids, and the autonomous seismic nodes can be washed, recharged, stored, and data transferred.

[0025] Applicant's U.S. Patent Publication 2019/0265378, entitled Automated Ocean Bottom Seismic Node Identification, Tracking, Deployment, and Recovery System and Method, is incorporated herein by reference in its entirety. Such a system discloses an ROV coupled to a subsea basket that carries nodes in the basket. The identification system is configured to track, select, deploy, and recover a particular seismic node by its unique identification number. The present application discloses an AUV instead of an ROV and a unique skid for coupling to the AUV for deployment and recovery to the seabed.

Autonomous Underwater Vehicle

[0026] FIGS. 1A-1D disclose one embodiment of an AUV according to the present disclosure. In one embodiment, an AUV may comprise a body with a propulsion system, a guidance system, an acoustic system, and a navigation system. The overall shape and design of the AUV is not necessarily important, as long as it is configured to travel subsea and couple with the disclosed node skid. In one embodiment, the disclosed AUV may be substantially similar in function to that disclosed in U.S. Pat. No. 9,891,333, incorporated herein by reference; such AUV components and AUV acoustic technology are well known in the art and are discussed in more detail below. Referring to FIG. 1A, AUV 101 may comprise front portion 103, back portion 105, upper portion 107, and lower portion 109. Referring to FIG. 1B, the AUV may comprise horizontal thrusters 111, which may be positioned at or near back portion 105. Referring to FIG. 1C, the AUV may comprise vertical thrusters 113, which may be positioned at either the front portion 103 and/or back portion 105 of the AUV. Referring to FIG. 1D, the AUV may comprise side thrusters 115, which may be positioned at the back portion 105 of the AUV.

[0027] As disclosed herein, the AUV is configured to hold a plurality of ocean bottom seismic nodes. The nodes can be located within the AUV itself, or can be handled by a separate node skid coupled to the AUV that may be removably attachable to the AUV. In still other embodiments, the node skid may be an integral or embedded part of the AUV such that the AUV and node skid are essentially considered a single unit. In general, a node skid, as described herein, is coupled to the AUV and holds a plurality of ocean bottom seismic nodes. The disclosed node skid may be removably attached to the AUV, and may comprise a variable buoyancy system as disclosed in more detail herein. Referring to FIGS. 1A-1D, node skid 131 is illustrated as being coupled in shape and form to AUV 101. In one embodiment, node skid 131 is coupled to the underside portion of the AUV, and may also be coupled to or formed around the sides of the AUV. In one embodiment, node skid 131 comprises a plurality of horizontal pipes 133, which may be located on one or more sides of the AUV/skid and/or on the middle of the skid such that when coupled with the AUV, pipes 133 may be located underneath the AUV.

[0028] In one embodiment, the AUV may comprise a propulsion system that may include one or more propellers or thrusters. A motor inside the AUV body may activate the propellers. Other propulsion systems may be used, e.g., jets, thrusters, pumps, etc. For example, the AUV may include one or more vertical thrusters (for vertical lift) and a plurality of horizontal thrusters (for lateral movement). The AUV may include one or more fins or wings for flight stabilization and/or increased AUV control. A motor may be controlled by a processor/controller. A processor may also be connected to a memory unit and tracking system, which may be configured for tracking the deployed cable and/or seismic nodes. One or more batteries may be used to power all these components.

[0029] The AUV may also include an inertial navigation system (INS) configured to guide the AUV to a desired location. An inertial navigation system includes at least one module containing accelerometers, gyroscopes, magnetometers or other motion-sensing devices. The INS is initially provided with the position and velocity of the AUV from another source, for example, a human operator, a global positioning system (GPS) satellite receiver, another INS from a surface vessel, etc., and thereafter, the INS computes its own updated position and velocity by integrating (and optionally filtering) information received from its motion sensors. The advantage of an INS is that it requires no external references in order to determine its position, orientation, or velocity once it has been initialized. As noted above, alternative systems may be used, as, for example, acoustic positioning systems. An optional acoustic Doppler Velocity Log (DVL) (not shown) can also be employed as part of the AUV, which provides bottom-tracking capabilities for the AUV. Sound waves bouncing off the seabed can be used to determine the velocity vector of the AUV, and combined with a position fix, compass heading, and data from various sensors on the AUV, the position of the AUV can be determined. This assists in the navigation of the AUV and provides confirmation of its position relative to the seabed.

[0030] Besides or instead of an INS, the AUV may include a compass and other sensors, such as, for example, an altimeter for measuring its altitude, a pressure gauge, an interrogator module, a homing beacon, etc. The AUV may optionally include an obstacle avoidance system and a communication device (e.g., Wi-Fi device, a device that uses an acoustic link) or another data transfer device capable of wirelessly transferring data. One or more of these elements may be linked to the processor. The AUV further includes an antenna (which may be flush with the body of the AUV) and corresponding acoustic system for subsea communications, such as communicating with the deploying, shooting, or recovery vessel (or other surface vessel) or an underwater base/station, ROV, or another AUV, or even the deployed nodes themselves. For surface communications (e.g., while the AUV is on a ship), one or more of antenna and communication devices may be used to transfer data to and from the AUV. Stabilizing fins and/or wings for guiding the AUV to the desired position may be used together with a propeller for steering the AUV. However, in one embodiment, the AUV has no fins or wings. The AUV may include a buoyancy system for controlling the AUV's depth and keeping the AUV steady after landing. In some embodiments, the AUV is neutrally buoyant in a body of water, whereas in other embodiments it may be positively buoyant or negatively buoyant. Those skilled in the art will appreciate that more or less modules or components may be added to or removed from the AUV based on the particular needs of the AUV.

[0031] The acoustic system utilized by the AUV may be an Ultra Short Baseline (USBL) system, sometimes known as a Super Short Base Line (SSBL). This system uses a method of underwater acoustic positioning. A complete USBL system includes a transceiver or acoustic positioning system mounted on a pole under a vessel (such as Hi-PAP, commercially available by Kongsberg) and a transponder on the AUV. In general, a hydro-acoustic positioning system consists of both a transmitter (transducer) and a receiver (transponder). An acoustic positioning system uses any combination of communications principles for measurements and calculations, such as SSBL. In one embodiment, the acoustic positioning system transceiver comprises a spherical transducer with hundreds of individual transducer elements. A signal (pulse) is sent from the transducer, and is aimed towards the seabed transponder. This pulse activates the transponder, which responds to the vessel transducer. The transducer detects this return pulse and, with corresponding electronics, calculates an accurate position of the transponder relative to the vessel based on the ranges and bearing measured by the transceiver. In one embodiment, to calculate a subsea position, the USBL system measures the horizontal and vertical angles together with the range to the transponder (located in the AUV in a typical SSBL configuration) to calculate a 3D position projection of the AUV relative the vessel. An error in the angle measurement causes the position error to be a function of the range to the transponder, so an USBL system has an accuracy error increasing with the range. Alternatively, a Short Base Line (SBL) system, an inverted short baseline (iSBL) system, or an inverted USBL (iUSBL) system may be used, the technology of which is known in the art. For example, in an iUSBL system, the transceiver is mounted on or inside the AUV while the transponder/responder is mounted on the surface vessel or ROV and the AUV has knowledge of its individual position rather than relying on such position from a surface vessel (as is the case in a typical USBL system). In another embodiment, a long baseline (LBL) acoustic positioning system may be used. In a LBL system, reference beacons or transponders are mounted on the seabed around a perimeter of a work site as reference points for navigation. The LBL system may use an USBL system to obtain precise locations of these seabed reference points. Thus, in one embodiment, the reference beacon may comprise both an USBL transponder and a LBL transceiver. The LBL system results in very high positioning accuracy and position stability that is independent of water depth, and each AUV can have its position further determined by the LBL system. The acoustic positioning system may also use an acoustic protocol that utilizes wideband Direct Sequence Spread Spectrum (DSSS) signals, which provides for a greater communications range in the water.

[0032] In one embodiment, the AUV uses one or more hydrogen fuel cells in addition to or as a replacement of the traditional rechargeable battery cells, such as lithium-ion based battery packs. The use of hydrogen fuel cells can extend the AUV's range from 25 km to approximately 50 km or more. A hydrogen fuel cell generates a direct current voltage, which in turn charges a battery pack. The battery pack when combined with a hydrogen fuel cell can be smaller capacity. In one embodiment, the hydrogen fuel cell provides enough power to supply all expected/normal load requirements (such as the thrusters and operating system), and the rechargeable power is used as emergency power should fuel cells fail. In one embodiment, the power supply chain is as follows: fuel cells to DCV generator to battery packs to PWM converters to BLDC motors to propellers. The power supply for the AUV can be switched between hydrogen fuel cell to battery power as needed, such as when approaching an active spread of nodes to reduce underwater noise interference on data. Any hydrogen (H.sub.2) or oxygen (O.sub.2) can be replaced onboard the surface platform and be replenished with additional supply runs by the PSV. In one embodiment, the AUV is configured to have its power supply reconfigured from a conventional battery source to a hydrogen fuel cell power source by swapping out specific modules in the AUV, which can be done on the surface platform or subsea operations. The AUV may have a variable buoyancy system (VBS) with one or more titanium tanks or Aluminum designed tanks for high pressure situations; one or more of these tanks may be repurposed for pressurized hydrogen and potentially oxygen storage for the hydrogen fuel cell power source.

[0033] U.S. Pat. No. 7,183,742 disclosed an unmanned underwater vehicle fuel cell powered charging system and method, which is incorporated herein by reference. Portions of such fuel cell technology may be utilized within the disclosed AUV. Likewise, Teledyne Energy Systems, Inc., offers a passive ejector fuel cell system for aerial and underwater vehicles, which can be utilized as the fuel cell for the disclosed AUV.

Skid for Node Handling

[0034] In general, a node skid, as described herein, is coupled to the AUV and holds a plurality of ocean bottom seismic nodes. The disclosed node skid may be removably attached to the AUV, and may comprise a variable buoyancy system as disclosed in more detail herein. In other embodiments, the node skid may be permanently attached embedded within the AUV. In still other embodiments, the AUV may comprise a large belly or void to hold the seismic nodes and to achieve the same functionality of the disclosed node skid without having a separate node skid.

[0035] One schematic of a coupled node skid, as disclosed herein, is illustrated in FIGS. 2A-2C. This may be substantially similar to node skid 131 as illustrated in FIGS. 1A-ID. Referring to FIG. 2A, AUV 201 may be coupled to node skid 211. Node skid 211 is configured to hold a plurality of ocean bottom seismic nodes 221a-221d. Node skid 211 may comprise one or more manipulator arms 213. One or more cameras (not shown) may also be located on the node skid. In one embodiment, the node skid comprises variable buoyancy system 215, which may comprise a plurality of pipes and a water displacement pump, discussed in greater detail below. Referring to FIG. 2B, the AUV and coupled node skid may be positioned within garage or basket 231 for handling or transport purposes. Referring to FIG. 2C, garage 231 may be lowered and raised from a marine surface vessel via tether 233. As also illustrated in FIG. 2C, the AUV and coupled node skid may be deployed from the garage for subsea operations.

[0036] The node skid and/or AUV is configured to transport and/or handle the seismic nodes to and from the seabed. In general, the disclosed skid may also be considered a platform, garage, or basket, as is known in the art. In one embodiment, the AUV is configured to travel subsea and a plurality of seismic nodes are positioned on the skid. In one embodiment, the skid can be attached to or detached from the AUV on the back deck of the marine vessel, in the sea, or on the seabed. The AUV and coupled skid may travel to and from the seabed and surface vessel with or without nodes. In the past, remotely operated vehicles (ROVs) have offered similar but different configurations and methods, such as those described in U.S. Pat. Nos. 6,975,560; 7,210,556; 7,324,406; 7,632,043; 8,310,899; 8,611,181; 9,090,319; 9,415,848; and 9,873,496, which are incorporated herein by reference in their entirety. In one embodiment, the skid is removably attached to the AUV, whereas in other embodiments the node skid is integrally formed and/or a part of the AUV. For example, the AUV may have a large belly or void space on the bottom in which the seismic nodes may be stored within and transferred to and from, as opposed to having a separate node skid removably attachable to the AUV. In one embodiment, the disclosed AUV need not actually handle the nodes itself, but rather moves the skid to the operable position subsea and/or on the seabed. In one embodiment, the skid has its own power source, while in other embodiments the skid utilizes a power source on the AUV when they are coupled together.

[0037] In one embodiment, the disclosed skid is a platform that can be coupled to the disclosed AUV. The skid may be configured to handle up to 50 seismic nodes or more, each with a payload of up to 25 kg in water. In general, a skid is separate from the AUV may be coupled and/or integrated with the AUV for power, control, and movement. It may be mounted beneath the AUV and secured with a plurality of fasteners, such as flanges or pins. It may be substantially cuboid or rectangular in shape, and may be streamlined to reduce drag. In one embodiment, the skid incorporates an integrated and automatic XYZ manipulator to position nodes to and from a storage position on the skid to the seabed. The manipulator may be integrated with a mission control system on the AUV for automatic control. As the seismic nodes need to be handled, the mission control system for the AUV and/or skid automatically handles the nodes at the appropriate time. The skid may be substantially neutrally buoyant in water, and may be formed of a flotation material and/or syntactic foam to keep the skid near neutral in the water. In one embodiment, the skid may comprise a variable buoyancy system (discussed in more detail below) to maintain the weight in water close to zero for the skid no matter the skid payload as it is deploying and retrieving nodes.

[0038] In one embodiment, the disclosed skid incorporates one or more cameras to target the seabed for identification of the seismic nodes and position of the nodes on the seabed. In one embodiment, the skid comprises two vertically down facing fixed cameras that are spaced apart a predetermined distance (such 30 centimeters or more). In one embodiment, the XYZ manipulator is positioned between equal distance from both of the cameras and is a fixed offset from the AUV navigation reference.

[0039] In one embodiment, the disclosed design of the skid reduces the form drag of the skid. In one embodiment, the disclosed skid incorporates a sliding section (see FIG. 1E) on a forward portion of the skid that moves forward to provide a handling bay for the manipulator to recover and deploy seismic nodes to and from the skid. The sliding section may be pushed forward by the manipulator and when the manipulator is recovered into the skid the sliding section can freely slide back into position. Alternatively, the handling may be opened/closed automatically by a separate motor or gear system or even closed with water pressure. Such a design effectively closes off the inside of the skid to prevent marine life entering and reducing drag as the AUV is travelling subsea.

[0040] In one embodiment, the skid may incorporate a system to control buoyancy so that the AUV can maintain a near even trim and a near neutral buoyancy (+/25 kg) throughout the dive, despite the variation in payload as the nodes are recovered or deployed. Such a system may be referred to as a variable buoyancy system, or VBS. In one embodiment, the VBS is configured from multiple pipes that work in parallel and are specially arranged to maintain the center of buoyancy (COB) near vertically above the center of gravity (COG). These pipes may be positioned on the sides of the AUV and/or underneath the AUV, by being located within or at different parts of the skid. The residual moment between these positions is handled by the use of vertical thrusters on the AUV that automatically control the trim and roll of the AUV to keep the AUV orientation near horizontal. In one embodiment, FIGS. 1A-ID illustrate pipes 133 of the VBS according to one embodiment. In another embodiment, FIG. 2A illustrates variable buoyancy system 215. Limited power supply for the skid and AUV is typically an issue, and requires optimized design of the AUV and skid. Location of the seismic nodes, VBS response, drag of the AUV and skid, and positions of the vertical and horizontal thrusters on the AUV are all important elements of the disclosed embodiment. In some embodiments, the disclosed VBS is part of the AUV as opposed to the node skid itself.

[0041] In one embodiment, the disclosed skid comprises a plurality of pressure chambers configured to input and output water from the chambers to vary the mass of the node skid. In one embodiment, the VBS comprises a plurality of pressurized chambers, tubes, vessels, or pipes arranged horizontally along the skid and running across the length of the skid, such that a metered water pump may deliver a mass of water into and out of the pipes to account for the node payload. In one embodiment, the pipes are positioned between the lateral thrusters of the AUV on the underside of the skid, but in other embodiments may be the top, bottom, or side of the AUV and/or skid. The pipes may be formed of aluminum or titanium and may have threaded end caps. The pipes may be arranged to optimize the Center of Gravity (CoG) of the mass that is added to correspond to maintaining the time of the vehicle. For example, as the seismic nodes move forward within the skid, the Center of Balance (CoB) is aligned with the CoG of the weight of the nodes.

[0042] In one embodiment, a weight of water equivalent to a weight of a seismic node is injected into the pipes as each node is deployed, and in reverse, water is ejected out of the pipes as each node is recovered. In one embodiment, the VBS uses a positive displacement pump (such as a high-pressure piston pump or screw pump) and sea water to act as a variable mass medium to vary the weight of the skid to account for the node payload. A volume of water is regulated by a motor RPM to match the change in weight required by the skid to maintain buoyancy or trim. The pump may use a torque conversion system to drive the pump with a small motor. Alternatively, to generate a given torque on the pump, the corresponding motor may use a closed loop fluid coupling or pressure intensification approach. In one embodiment, each horizontal pipe has an internal floating piston that separates the compressed gas from the seawater. In one embodiment, one or more dump valves may be utilized to relieve internal pressure when the skid is being recovered to the back deck of the marine vessel.

Deployment and Retrieval System

[0043] In one embodiment, the disclosed AUV (and coupled node skid) may be deployed by a surface vessel or surface platform to a subsea depth via a garage or basket. FIGS. 2B and 2C illustrate the schematics of one embodiment of such a basket, AUV, and skid. FIGS. 3A-3C and FIGS. 4A-4B illustrate deployment and handling steps of the garage from a marine surface vessel.

[0044] One embodiment of a garage is illustrated in FIGS. 3A and 3B. FIG. 3A illustrates AUV 101 and coupled skid node 131 enclosed within garage, cage, or basket 311 positioned next to manipulator arm 301 on the back deck of marine vessel 300. The surface manipulator arm has an attachment point 303 that can couple to the garage for deploying and retrieving the garage from the back deck of the surface vessel. A garage transport system 313 may be located on the back deck to move the garage from one position on the back deck to another position on the back deck, at which point the AUV may be removed from the garage and seismic nodes removed from the AUV and/or node skid. The manipulator arm is known to those of skill in the art, and can be part of any conventional LARS system for ROV systems on a surface vessel.

[0045] Comparing FIGS. 3A and 3B, in FIG. 3B AUV 111a has been removed from the garage and is being transported to a cleaning or storage station. Further, an upper shell of AUV 111a has been removed to show some of the internal components of the AUV. In FIG. 3B, other AUVs are displayed in sequence that are being handled on the back deck. For example, AUV 111b is still contained within garage 311b, and AUV 111c is being transported on transport system 313. FIG. 3C shows AUV handling system 313 without a cage or AUV or skid attached to the handling system. In one embodiment, the handling system comprises a series of rails 312 arranged on the back deck of the vessel to move the AUVs, garages, and/or node skids between different back deck positions. Elevated rail assemblies 316 may be positioned on rails 312 for movement within the transport system and to move nodes, node skids, garages, or AUVs on the back deck of the vessel.

[0046] FIGS. 4A-4B illustrate one embodiment of deploying an AUV from a back deck of a marine vessel according to one embodiment of the present disclosure. As displayed in FIGS. 4A and 4B, surface manipulator arm 301 is located near a side of surface vessel 300 for deploying and retrieving garage 431 over a side of the surface vessel. In other embodiments, a moon pool may be located in the center of the vessel and the arm or similar winching system is configured to raise and lower the garage from the middle or bottom of the surface vessel. A plurality of AUVs may be positioned on the deck of the surface vessel on a handling system or transport system. After the AUV (with or without a skid) is positioned within a cage, arm 301 attaches to the cage and moves the cage 431 (and coupled AUV 401 and node skid 411) from the back deck of the vessel to over a side of the vessel. FIG. 4B shows cage 431 being lowered into a body of water via tether 303 and after a point where AUV 401 (and coupled node skid 411) has moved away from the cage. Depending on the deployment operation, the cage can stay at a position subsea, can be raised to the surface to obtain another AUV, or a second AUV that is in the ocean can be retrieved into the cage and raised back to the surface vessel. In general, the retrieval operations of the AUV are opposite to that of the deployment method described above.

[0047] When lowered from the surface vessel, the AUV may or may not have a coupled node skid that holds a plurality of seismic nodes as described herein. Once lowered from the surface vessel and at a desired subsea position, the AUV may depart from the garage for its mission operation. The garage may stay at that position or be raised to the surface vessel. A second AUV, after completing its subsea mission, may dock with the garage and be recovered to the surface vessel.

[0048] In one embodiment, the garage may touchdown on the seabed while the AUV is docked/undocked, while in other embodiments the docking steps may be done at a depth above the seabed. The AUV may automatically enter or leave the garage based on acoustic beacons positioned on the garage for triangulation purposes. In one embodiment, the departing AUV may acoustically communicate with an incoming AUV the garage heading for better positioning of the AUVs. The garage may or may not contain thrusters for better positioning/aligning purposes subsea. The garage may be powered and/or tethered to a surface vessel for power/communications. The garage may have real time video cameras, thrusters, and a manipulator for handling dead AUVs or seismic nodes. The garage may have locking mechanisms to securely transfer an AUV to and from the seabed and the surface vessel.

[0049] In one embodiment, when the garage is landed on the back deck, it fully interfaces with a containerized deployment system for handling of the autonomous seismic nodes coupled to the AUV. In one embodiment, a front sliding section of the node skid may be pushed open and the seismic nodes may be placed onto a conveying system that transports the seismic nodes into the back deck containerized system, at which point they can be washed, data downloaded, recharged, and stored. Loading of the node skid is a reverse process using the same equipment.

[0050] When a seismic node is placed on the seabed, a picture may be taken by the AUV or node skid of the seismic node during touchdown, which provides additional confirmation of the touchdown position of the seismic node. Such a position may be automatically inputted into the relevant database for the particular node. For the present disclosure, touchdown is the point of contact of a seismic node to the seabed. Once the node is positioned on the seabed, the touchdown position may be automatically recorded (such as by a position fix and/or a picture) and associated with the particular seismic node in a database. In one embodiment, an automated control systemwhich may be combined with the AUV navigation system-manages the operations of seismic node identification, handling, and placement. For example, for any particular operation, a particular seismic node may be selected by the AUV and the ID and position of seismic nodes on the displayed on a user interface. Such features allow real time knowledge of the position of all seismic nodes during a deployment operation and increased operational control of the deployment and recovery process of the seismic nodes. Such automatic identification, tracking, deployment, and recovery of seismic nodes is more fully described in Applicant's U.S. Patent Application Publication No. 2019/0265378, incorporated herein by reference in its entirety, which discloses a ROV with a coupled skid.

[0051] Once the desired node has been placed on the seabed, the AUV navigation system will automatically guide the AUV to the next seabed position where the next seismic node is to be placed. In one embodiment, each of the predetermined seabed node positions (which may be in the order of hundreds or thousands) has been determined and, based on the desired deployment system, a list of specific actions and/or steps has been generated to compose the most efficient deployment operation and/or scheme of the seismic nodes. In one embodiment, after positioning an AUV over a node position, the AUV may estimate the XY offset and then lock that position into the navigation system of the AUV as a vehicle reference point. As the AUV descends to the seabed (either on deployment or recovery of the seismic node), a manipulator arm may make contact with the target node using onboard IMU and DVL.

[0052] In one embodiment, a surface platform may be utilized instead of a surface vessel. The surface platform may comprise conventional LARS unit for the deployment of ROVs, AUVs, and baskets to the seabed. A plurality of AUVs and subsea garages may be placed on the platform during deployment and retrieval operations. In one embodiment, when the garage is landed on the deck platform, it fully interfaces with the containerized deployment system for the autonomous seismic nodes where they can be washed, recharged, stored, and data transferred.

[0053] In one embodiment, the disclosed AUV and a garage may be deployed from a floating surface platform to a subsea depth. The AUV may or may not have a coupled node skid that holds a plurality of seismic nodes as described herein. At such a point, the AUV may depart the garage for its mission operation. The garage may stay at that position or be raised to the platform. A second AUV, after completing its subsea mission, may dock with the garage and be recovered to the platform. In one embodiment, the garage may touchdown on the seabed while the AUV is docked/undocked, while other embodiments the docking steps may be done at a depth above the seabed. The AUV may automatically enter or leave the garage based on acoustic beacons positioned on the garage for triangulation purposes. In one embodiment, the departing AUV may acoustically communicate with an incoming AUV the garage heading for better positioning of the AUVs. The garage may or may not contain thrusters for better positioning/aligning purposes subsea. The garage may be powered and/or tethered to a surface platform for power/communications, and may be considered as a powered ROV. The garage may have real time video cameras, thrusters, and a manipulator for handling dead AUVs or seismic nodes. The garage may have locking mechanisms to securely transfer an AUV to and from the seabed and the surface platform.

[0054] Many other variations in the overall configuration of the skid, garage, and AUV are possible within the scope of the invention. For example, the skid and AUV may be integrated such that it is considered as a single unit. The skid may be removably attached to the AUV, permanently attached to the AUV, or embedded or integrated within the AUV. In one embodiment, the AUVs and seismic nodes may be deployed by a surface vessel, while in other embodiments they may be deployed by a surface platform. The surface platform may or may not be an oil and gas production platform. The AUV may have one or more hydrogen fuel cells instead of rechargeable battery cells. It is emphasized that the foregoing embodiments are only examples of the very many different structural and material configurations that are possible within the scope of the present invention.

[0055] Although the invention(s) is/are described herein with reference to specific embodiments, various modifications and changes can be made without departing from the scope of the present invention(s), as set forth in the claims below. Accordingly, the specification and figures are to be regarded in an illustrative rather than a restrictive sense, and all such modifications are intended to be included within the scope of the present invention(s). Any benefits, advantages, or solutions to problems that are described herein with regard to specific embodiments are not intended to be construed as a critical, required, or essential feature or element of any or all the claims.

[0056] Unless stated otherwise, terms such as first and second are used to arbitrarily distinguish between the elements such terms describe. Thus, these terms are not necessarily intended to indicate temporal or other prioritization of such elements. The terms coupled or operably coupled are defined as connected, although not necessarily directly, and not necessarily mechanically. The terms a and an are defined as one or more unless stated otherwise. The terms comprise (and any form of comprise, such as comprises and comprising), have (and any form of have, such as has and having), include (and any form of include, such as includes and including) and contain (and any form of contain, such as contains and containing) are open-ended linking verbs. As a result, a system, device, or apparatus that comprises, has, includes or contains one or more elements possesses those one or more elements but is not limited to possessing only those one or more elements. Similarly, a method or process that comprises, has, includes or contains one or more operations possesses those one or more operations but is not limited to possessing only those one or more operations.