Patent Publication Number: US-2023146618-A1

Title: Pop-up seabed seismic node

Description:
PRIORITY 
     This application claims priority to U.S. provisional patent application No. 63/277,907, filed on Nov. 10, 2021, the entire contents of which is incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
     This invention relates to marine seismic systems and more particularly relates to autonomous seismic nodes that may be deployed on the seabed. 
     Description of the Related Art 
     Marine seismic data acquisition and processing generates a profile (image) of a geophysical structure under the seafloor. Reflection seismology is a method of geophysical exploration to determine the properties of the Earth&#39;s subsurface, which is especially helpful in determining an accurate location of oil and gas reservoirs or any targeted features. Marine reflection seismology is based on using a controlled source of energy (typically acoustic energy) that sends the energy through seawater and subsurface geologic formations. The transmitted acoustic energy propagates downwardly through the subsurface as acoustic waves, also referred to as seismic waves or signals. By measuring the time it takes for the reflections or refractions to come back to seismic receivers (also known as seismic data recorders or nodes), it is possible to evaluate the depth of features causing such reflections. These features may be associated with subterranean hydrocarbon deposits or other geological structures of interest. 
     In general, either ocean bottom cables (OBC) or ocean bottom nodes (OBN) are placed on the seabed. For OBC systems, a cable is placed on the seabed by a surface vessel and may include a large number of seismic sensors, typically connected every 25 or 50 meters into the cable. The cable provides support to the sensors, and acts as a transmission medium for power to the sensors and data received from the sensors. One such commercial system is offered by Sercel under the name SeaRay®. Regarding OBN systems, and as compared to seismic streamers and OBC systems, OBN systems have nodes that are discrete, autonomous units (no direct connection to other nodes or to the marine vessel) where data is stored and recorded during a seismic survey. One such OBN system is offered by the Applicant under the name Manta®. See, e.g., U.S. Pat. No. 9,523,780. For OBN systems, seismic data recorders are placed directly on the ocean bottom by a variety of mechanisms, including by the use of one or more of Autonomous Underwater Vehicles (AUVs), Remotely Operated Vehicles (ROVs), by dropping or diving from a surface or subsurface vessel, or by attaching autonomous nodes to a cable that is deployed behind a marine vessel. See, e.g., U.S. Pat. No. 9,784,873. In other embodiments, the seismic node may be integrated with an AUV. One such OBN system is offered by the Applicant under the name Spicerack®. See, e.g., U.S. Pat. Nos. 9,873,496; 10,322,783; 10,543,892. 
     Autonomous ocean bottom seismic 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 nodes are well known in the art, and may have any number of configurations. Other prior art systems include a deployment rope/cable with integral node casings or housings for receiving autonomous seismic nodes or data recorders. Traditional prior art nodes are often made of tubes of various shapes that are joined and/or coupled together with cables, which can be vulnerable to handling and assembly errors. Other prior nodes can be made of spherical glass pressure housings that need additional protection and are less than ideal for storage, handling, and stability when on the seabed. Other prior are nodes are expensive to manufacture and difficult to deploy and couple to the seabed. 
     The referenced shortcomings are not intended to be exhaustive, but rather are among many that tend to impair the effectiveness of previously known techniques in seafloor deployment systems; however, those mentioned here are sufficient to demonstrate that the methodologies appearing in the art have not been satisfactory and that a significant need exists for the systems, apparatuses, and techniques described and claimed in this disclosure. 
     A need exists for an improved autonomous seismic node design for automated node deployment, recovery, handing, and storage. A need exists for a node that provides increased operational parameters, increased seabed coupling, and more versatile deployment options. A need exists for a seismic node design that can be mass-produced in a cost-effective manner. A need exists for a node that can be used in multiple deployment configurations. A need exists for a seismic node design that enables large numbers of nodes to be operated in the field. 
     SUMMARY OF THE INVENTION 
     An autonomous seismic node that is configured for free-fall from the water surface to the seabed and that is capable of popping up and/or rising from the seabed to the water surface on its own. The seismic node is substantially cylindrical and/or tubular in shape and is positively buoyant in water. The node comprises an upper end cap assembly and a lower end cap assembly, each of which is inserted into an end of the tubular housing. The seismic node may be coupled to an anchor weight system to assist in free fall to the seabed, or may be coupled to a seabed coupling device that allows for traditional seabed seismic recording. The anchor weight system may comprise a first part coupled to the seismic node via a tether, and a second part directly attached to the seismic node, each of which may be separately released from the seismic node. The seismic node is positively buoyant, and may be coupled to a detachable/removable anchor weight that provides an overall negative buoyancy to the node and assists in free fall of the seismic node to the seabed. The detachable weight system may be comprised of two separately detachable parts—a first part that comprises a heavy anchor weight and a second part that is not as dense and which gives the seismic node approximately neutral buoyancy. The lower end cap assembly may contain the seismic sensors and battery cells, and the upper end cap assembly may contain any acoustic devices. A plurality of seismic nodes may be dropped from a surface vessel into a body of water, and free-fall to the seabed. After seismic recording is performed as is known in the art, the anchor weight and/or seabed coupling device may be detached, thereby causing the seismic node to rise to the water surface based on the positive buoyancy of the device. 
     An autonomous seismic node is configured for free-fall from a water surface to the seabed and is capable of rising from the seabed on its own. The seismic node is positively buoyant in water and is substantially tubular in shape, with a length to a diameter ratio of 4:1 or greater. The node comprises a lower section and an upper section, each of which is inserted into an end of a tubular housing. The lower section has a lower end cap assembly with a release mechanism and the upper section has an upper end cap assembly with a plurality of electronic components and a detachable lifting cage. The seismic node may be coupled to a detachable anchor weight or seabed coupling device to assist in free fall to the seabed, and when detached after seismic recording is performed, allows the seismic node to rise to the water surface. 
     Disclosed is an autonomous seismic node for deployment to the seabed, that comprises a pressurized node housing, wherein at least one seismic sensor, at least one data recording unit, and at least one clock are located within the pressurized node housing, and wherein the node housing is substantially tubular and has a length to a diameter ratio of 4:1 or greater. The node housing may have a length to diameter ratio of 8:1 or greater. The node housing may have a center of gravity and a center of buoyancy, wherein the center of gravity is below the center of buoyancy. The node housing may have an internal buoyancy chamber, such that the node housing is positively buoyant. The buoyancy chamber may be empty space or may be buoyant materials that are less dense than water. The seismic node may comprise a detachable lifting cage coupled to an upper section of the node housing. 
     The seismic node may have a node housing that comprises an upper section, a lower section, an upper end cap assembly coupled to the upper section, and a lower end cap assembly coupled to the lower section. The end cap assemblies may be coupled to the upper and lower sections of the node housing via a plurality of clips. Each of clips may be substantially flat and have wedge and/or dog-boned shapes. A first plurality of clips may attach the upper end cap assembly to the node housing and a second plurality of clips may attach the lower end cap assembly to the node housing. Each of the first plurality of clip may fit within a first plurality of corresponding recesses on the upper section and the upper end cap assembly and the second plurality of clip may fit within a second plurality of corresponding recesses on the lower section and the lower end cap assembly. The upper end cap assembly may have a hydrophone, an acoustic transducer, a satellite transducer, and an electronic connector. The lower cap assembly may be comprise a release mechanism, which may be coupled to a tether, anchor weight, or seabed coupling device that can be detached from the seismic node. The lower cap assembly may comprise and/or be coupled to a plurality of battery cells and a plurality of seismic sensors within the node housing. The upper and lower end cap assemblies may comprise a polymer material. 
     The seismic node may further comprise at least one anchor weight coupled to the node housing that is configured to be released from the seismic node by an acoustic signal. The seismic node housing may be positively buoyant in water. The at least one anchor weight may be coupled to the node housing via a flexible tether or directly attached to the bottom of the seismic node. The at least one anchor weight may comprise a seabed coupling device. The at least one anchor weight may comprise a first anchor weight and a second anchor weight, such that the first anchor weight is directly attached to the node housing and the second anchor weight is coupled to the first anchor weight via a tether, wherein the first anchor weight is positioned between the seismic node and the second anchor weight. The first and second anchor weights can be released from the seismic node by an acoustic signal by the use of a release mechanism assembly on the lower end cap of the seismic node. The second anchor weight may be coupled to the seabed when the seismic node is near the bottom of the ocean and has fully descended. A combination of the seismic node housing and the at least one anchor weight may be negatively buoyant in water. A combination of the seismic node and the first anchor weight may be approximately neutrally buoyant in water. A combination of the seismic node, the first anchor weight, and the second anchor weight may be negatively buoyant in water. The first and second anchor weights may be different weights, such that the second anchor weight is heavier than the first anchor weight. 
     The seismic node comprises a positively buoyant section and a negatively buoyant section, wherein the negatively buoyant section is removably detached from the positively buoyant section. The negatively buoyant section may comprise an anchor weight or a seabed coupling device. The positively buoyant section may comprise an internal buoyancy chamber of the seismic node, or may comprise an external buoyancy jacket or sleeve. The seismic node may comprise or be coupled to a flotation jacket configured to substantially surround the seismic node housing. The combination of the seismic node housing and the flotation jacket may be positively buoyant in water. 
     Disclosed is an autonomous seismic node for deployment to the seabed, comprising a pressurized node housing, wherein at least one seismic sensor, at least one data recording unit, and at least one clock are located within the pressurized node housing, and an anchor weight removably attached to a lower section of the node housing. The node housing may be substantially tubular and/or cylindrical and has a length to a diameter ratio of 4:1 or greater. An upper section and a lower section may be inserted into the node housing. An anchor weight may be coupled to the node housing via a flexible tether. The anchor weight may comprise a seabed coupling device that is directly coupled to the node housing. The seabed coupling device may comprise one or more of a plate, a tripod, a tripod base, one or more ribbed spears, and/or an open-ended pipe base. The anchor weight may comprise a biodegradable material. The anchor weight may be configured to be released from the seismic node by an acoustic signal. 
     Disclosed is a method for deploying an autonomous seismic node to the seabed, comprising providing a seismic node on a back deck of a marine vessel, coupling an anchor weight to the node housing while the seismic node is on the back deck of the marine vessel, and deploying the seismic node with the coupled anchor weight from the surface vessel to the bottom of the ocean. The method may further comprise coupling the anchor weight to the bottom of the ocean. The method may further comprise retrieving the node housing from the bottom of the ocean. The method may further comprise releasing the anchor weight from the node housing based on an acoustic signal and surfacing the node housing near a surface of a body of water. The method may further comprise recording seismic signals on the ocean bottom. The seismic node may comprise a pressurized node housing, wherein at least one seismic sensor, at least one data recording unit, and at least one clock are located within the pressurized node housing, wherein the node housing is substantially tubular and has a length to a diameter ratio of 4:1 or greater. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       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. 
         FIG.  1 A  is a schematic diagram illustrating one embodiment of an autonomous seismic node according to the present disclosure. 
         FIG.  1 B  is a schematic diagram illustrating another embodiment of an autonomous seismic node according to the present disclosure. 
         FIGS.  2 A- 2 C  illustrate perspective views of one embodiment of an autonomous seismic node according to the present disclosure. 
         FIGS.  3 A- 3 B  illustrate an internal configuration of one embodiment of the autonomous seismic node from  FIGS.  2 A- 2 C . 
         FIGS.  4 A- 4 B  illustrate one embodiment of an autonomous seismic node coupled to a seabed coupling device according to the present disclosure. 
         FIGS.  5 A- 5 C  illustrate one embodiment of an autonomous seismic node coupled to a seabed coupling device according to the present disclosure. 
         FIGS.  6 A- 6 B  illustrate one embodiment of an autonomous seismic node coupled to a seabed coupling device according to the present disclosure. 
         FIGS.  7 A- 7 D  illustrate one embodiment of an autonomous seismic node according to the present disclosure. 
         FIGS.  8 A- 8 D  illustrate one embodiment of an upper end of the autonomous seismic node of  FIG.  7 A . 
         FIGS.  9 A- 9 G  illustrate one embodiment of an upper end of the autonomous seismic node of  FIG.  7 A . 
         FIGS.  10 A- 10 F  illustrate one embodiment of a lower end of the autonomous seismic node of  FIG.  7 A . 
         FIGS.  11 A- 11 B  illustrate one embodiment of an autonomous seismic node with a flotation jacket according to the present disclosure. 
         FIGS.  12 A- 12 F  illustrate multiple views of one embodiment of the autonomous seismic node from  FIGS.  11 A- 11 B . 
         FIG.  13    illustrates one embodiment of a storage container for a plurality of autonomous seismic nodes according to one embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     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. 
     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 
     Disclosed is an autonomous seismic node that, in one embodiment, is designed for free-fall from the water surface to the seabed and that is capable of popping up and/or rising from the seabed to the water surface on its own. In one embodiment, the seismic node is substantially cylindrical and/or tubular in shape. The seismic node may have a length to a diameter ratio of 4:1 or greater. The seismic node comprises a positively buoyant section and a negatively buoyant section, wherein the negatively buoyant section is removably detached from the positively buoyant section. The seismic node may be coupled to one or more anchor weights. The anchor weight may be directly coupled to the seismic node or coupled to the seismic node via a flexible tether. In other embodiments, the anchor weight may be a seabed coupling device that allows for traditional seabed seismic recording. The seismic node comprises one or more seismic sensors that are configured to record seismic signals while on the ocean floor, a digital recording device, a clock, and one or more power sources (such as battery cells). The seismic node may also have a radio or satellite transponder with GPS positioning capability and any necessary acoustic communication devices, such as an integrated USBL. In one embodiment, the seismic node comprises an upper end cap assembly and a lower end cap assembly, each of which is inserted into the tubular housing. The lower end cap assembly may be coupled to the geophones and battery cells, and the upper end cap assembly may be coupled to any acoustic devices. A buoyancy chamber may be located between the upper and lower end cap assemblies to provide positive buoyancy to the seismic node. 
     In one embodiment, a plurality of seismic nodes may be dropped from a surface vessel into a body of water, and free-fall to the bottom of the water, such as the seabed. The combination of the seismic node and the coupled anchor weight is overall negatively buoyant, such that the seismic node sinks to the ocean bottom. On the seafloor the position and orientation of the seismic node must be known, and in one embodiment the location of each seismic node may be determined by USBL position and any necessary acoustic transducers. After seismic recording is performed, as is known in the art, the anchor weight and/or seabed coupling device may be detached, thereby causing the seismic node to rise to the water surface based on the overall positive buoyancy of the device without the anchor weight. In one embodiment, the seismic node is configured to receive an acoustic command to autonomously return to the surface at the end of the survey and release any anchor weight for the seismic node to rise. In one embodiment, the seismic node does not have a separate propulsion system (and is thus not an AUV), and merely falls to and rises from the seabed based on its own static buoyancy. 
     In one embodiment, the seismic node is designed for rapid descent and minimal drift during descent to the seabed due to lateral current forces. The design and configuration of the seismic node is ideal for storage and transportation. In one embodiment (see  FIG.  1 A ), the seismic node is positively buoyant, and may be coupled to a detachable/removable anchor weight that provides an overall negative buoyancy to the node and assists in free fall of the seismic node to the seabed. In other embodiments (see  FIG.  1 B ), the detachable weight system may be comprised of two separate parts—a first part that comprises a heavy anchor weight and rests on the seabed and a second part directly attached to the seismic node that is not as dense and which gives the seismic node approximately neutral buoyancy in the water. In both embodiments, a tether couples the seabed anchor to a detachable device (such as a release assembly mechanism) on the seismic node housing. 
       FIG.  1 A  is a schematic diagram illustrating one embodiment of an autonomous seismic node according to the present disclosure. As illustrated, the shape of the seismic node  101  (formed by the outer housing) is substantially cylindrical and/or tubular. The seismic node may have a length to a diameter ratio of 4:1 or greater, such as approximately 5:1, 6:1, 7:1, 8:1, or greater. In one embodiment, the diameter may be approximately 6″ and the length may be approximately 60″. In one embodiment, seismic node  101  comprises a seismic node housing that is made of any variety of materials, such as aluminum, titanium, or plastic. Portions of the node housing may be metal, while portions of the node housing (such as the end caps) may be non-metallic such as a polymer. The housing may be a pressure resistant housing that is capable of withstanding water depths of 3000 meters or greater. It is a pressurized node housing, meaning that the pressurization is any measurable pressure above 0 psia. The node housing may be directly coupled or indirectly coupled (such as via a flexible tether) to anchor weight  123 . The anchor weight facilitates free fall of the seismic node from the water surface to the bottom of the ocean, and helps the seismic node to stay coupled to the seabed. Tether  121  may be coupled to release assembly  119  of the seismic node, which may be on the inside or outside of the seismic node. The release assembly may be electronic or mechanical, and is configured to release the anchor weight from the seismic node at the appropriate time, such as when the seismic recording is finished and it is desired to retrieve the seismic node. In one embodiment, the release assembly is activated based on an acoustic signal. In one embodiment, there is only one release mechanism such that activation of the release mechanism releases the heavy weight anchor and coupled tether and the piece coupled to the seismic node to which the tether attaches. In one embodiment, releasing and/or de-coupling the anchor weight from the seismic node allows the seismic node to pop up and/or rise to the water surface for retrieval based on the positive buoyancy of the node itself. In one embodiment, a plurality of seismic nodes (such as hundreds or thousands) are stored on a surface vessel, and can be deployed from the surface to the seabed based on manual or automatic methods. In one embodiment, the anchor weights are attached to the node housing immediately prior to being deployed in the water. In one embodiment, when the seismic nodes are desired to be retrieved, the anchor weight is decoupled from the seismic node and the seismic node is able to rise or pop-up to the water surface for retrieval by the surface vessel. In one embodiment, the seismic node contains large internal volume  114  for buoyancy purposes, such that the seismic node itself is positively buoyant in water. In one embodiment, the anchor weight is configured to offset the positive buoyancy of the seismic node such that, when coupled to the seismic node, the seismic node and anchor weight is negatively buoyant to free fall to ocean bottom  103 . In one embodiment, no external flotation device to the seismic node is required. 
     FIG .  1 B is a schematic diagram illustrating another embodiment of an autonomous seismic node  101  according to the present disclosure. The embodiment in  FIG.  1 B  is substantially similar to that as illustrated in  FIG.  1 A  but for the anchoring mechanism.  FIG.  1 A  includes a one part anchor system (the heavy anchor weight), while  FIG.  1 B  includes a two part anchor system. In both embodiments, the seismic node is naturally self-buoyant, and is made negatively buoyant by coupling one or more anchor weights to the seismic node that provides an overall negative buoyancy to the node and assists in free fall of the seismic node to the seabed. Such anchor weights can be removably coupled to the seismic node via an indirect connection (such as a tether) or a direct attachment to the seismic node housing. In the embodiment of  FIG.  1 B , a first part of the anchor system comprises a light anchor weight and a second part comprises a heavy weight anchor. In this embodiment, heavy weight anchor  123  is coupled to lighter weight anchor  133  by tether  121 , and lighter weight anchor  133  is directly attached to seismic node housing  101  via or proximate to release assembly  119 . The lighter weight anchor helps to keep the node neutrally buoyant in the water, which may assist in seismic water coupling for better seismic recording. In one embodiment, there is only one release mechanism such that activation of the release mechanism releases the lighter weight anchor and the coupled heavy weight anchor and tether. When the seismic node is ready to be released from the seabed, all three parts (seabed anchor, tether, and light weight anchor) are left on the seabed. In one embodiment, an acoustic signal to the release assembly provides an electronic signal to the motor to release the tether (to detach the anchor). Similarly, an acoustic signal or time delay (or other mechanisms) can provide a signal to release the intermediate anchor for ascent. Release assembly  119  can attach to the anchor weight, baseplate, or tether using several methods such as a threaded interface, a spring loaded catch, an over center or sliding latch, or a fusible link or any combination thereof. A threaded interface may be preferential as it can be tightened to prevent the anchor weight, baseplate, or tether from moving relative to the node body and generating noise that could be picked up by the seismic sensor(s). A threaded interface on the release mechanism can use a small, low power motor coupled with a gear box to obtain adequate clamping force. A reciprocal threaded interface may be placed or attached to the anchor weight, baseplate, or tether, and the two parts tighten against each other during assembly outside of the water or on the back deck of the vessel. 
     In one embodiment, the node housing may contain electronics internally and externally to the housing, as is known in the art. On the upper end of the housing may be located various external acoustic devices and/or communication devices  111 , such as a USBL transducer, antennae, hydrophones, and other connectors, as is known in the art. Within the housing may be located all of the electronic equipment, such as seismic recording devices  117  (geophones), PCB assemblies  113 , battery packs  115 , etc. 
     In one embodiment, the battery cells may be lithium-ion battery cells or rechargeable battery packs for an extended endurance (such as 90 days) on the seabed, but one of ordinary skill will recognize that a variety of alternative battery cell types or configurations may also be used. Additionally, the seismic node may include a pressure release valve configured to release unwanted pressure from the seismic node at a pre-set level. The valve protects against fault conditions like water intrusion and outgas sing from a battery package. Additionally, the seismic node may include an electrical connector configured to allow external access to information stored by internal electrical components, data communication, and power transfer. During the deployment the connector may be covered by a pressure proof watertight cap. In other embodiments, the node does not have an external connector and data is transferred to and from the node wirelessly, such as via electromagnetic or optical links. 
     In an embodiment, the internal electrical components may include one or more hydrophones, one or more (preferably three) geophones or accelerometers, and a data recorder. In an embodiment, the data recorder may be a digital autonomous recorder configured to store digital data generated by the sensors or data receivers, such as the hydrophone and the one or more geophones or accelerometers. One of ordinary skill will recognize that more or fewer components may be included in the seismic node. For example, there are a variety of sensors that can be incorporated into the node including and not exclusively, inclinometers, rotation sensors, translation sensors, heading sensors, and magnetometers. Except for the hydrophone, these components are preferably contained within the node housing that is resistant to temperatures and pressures at the bottom of the ocean, as is well known in the art. 
     In one embodiment, the seismic sensor may include one or more of a hydrophone, geophone, accelerometer, etc. For example, if a 4C (four component) survey is desired, the seismic sensors may include three geophones and a hydrophone, i.e., a total of four sensors. Alternatively, the seismic sensor may additionally include one or more accelerometers. Of course, other sensor combinations are possible, and may include one or more of a hydrophone, geophone, accelerometer, electromagnetic sensor, depth sensor, MEMs, Inertial Measurement Unit (IMU) or a combination thereof and which could be used together to measure up to six degrees of freedom. The seismic sensor may be located completely or partially inside body housing, while in some embodiments it may be located outside body housing when better water coupling/exposure is needed (e.g., for hydrophones). A memory unit may be connected to processor and/or seismic sensor for storing seismic data recorded by seismic sensor. A power system (such as one or more batteries) may be used to power all these components. The node may also include a clock and digital data recorder (not shown). 
     The seismic node may include a compass and other sensors as, for example, an altimeter for measuring its altitude, a pressure gauge, an interrogator module, etc. The node may optionally include an obstacle avoidance system and a communication device (e.g., Wi-Fi or other wireless interface, such as a device that uses an acoustic link) or other data transfer device capable of wirelessly transferring seismic data and/or control status data. One or more of these elements may be linked to processor. The seismic node may further include an antenna (which may be flush with or protrude from the housing) and a corresponding acoustic system for subsea communications. For surface communications (e.g., while the seismic node is on a ship), one or more of an antenna and communication device may be used to transfer data to and from the seismic node. 
     The seismic node systems may use an acoustic system as is known in the art. The acoustic system may be an Ultra-Short Baseline (USBL) system, also sometimes known as Super Short Base Line (SSBL) or Short Base Line (SBL) This system uses a method of underwater acoustic positioning. A complete USBL system may include a transceiver or acoustic positioning system mounted on a pole under a vessel or ROV (such as Hi-PAP or μPAP, commercially available by Kongsberg and Sonardyne) and a transponder on the seismic node. In general, a hydro-acoustic positioning system consists of both a transmitter and a receiver, and any Hi-PAP or μPAP or transponder system acts as both a transmitter and a receiver. 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 (such as a Hi-PAP or μPAP head on the surface vessel), and is aimed towards the seabed transponder located on the seismic node. This pulse activates the transponder on the seismic node, which responds to the vessel transducer after a short time delay. The transducer detects this return pulse and, with corresponding electronics, calculates an accurate position of the transponder (seismic node) 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 seismic node) to calculate a 3D position projection of the seismic node relative to a separate station, basket, ROV, or 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 seismic node while the transponder/responder is mounted on a separate vessel/station and the seismic node 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 seismic node 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. In one embodiment, the seismic node is equipped with a plurality of communication devices, such as an USBL beacon capable of receiving and transmitting acoustic signals, a phased array receiver (or system) that is able to determine the direction of an incoming acoustic signal by analysis of the signal phase, and an acoustic modem. 
     Those skilled in the art would appreciate that more or less components and electronic devices may be added to or removed from the seismic node. 
     Node Design 
       FIGS.  2 A- 2 C  illustrate perspective views of one embodiment of an autonomous seismic node according to the present disclosure.  FIG.  2 A  illustrates a perspective view of seismic node  200  with seismic node housing  201 , which may be substantially similar to the seismic node in  FIG.  1 A . Node  200  and node housing  201  is substantially cylindrical and/or tubular. In one embodiment, the seismic node and/or housing has a length to width ratio of at least 4:1, and in some embodiments may be up to approximately 10:1.  FIG.  2 B  illustrates top end  211  of the node from  FIG.  2 A , while  FIG.  2 C  illustrates bottom end  221  of the node from  FIG.  2 A . Each end is able to be screwed in and/or coupled to node housing  201  to obtain a water tight and pressure tight seismic node, which provides a pressurized node housing for the internal electronic components. As illustrated in  FIG.  2 B , a plurality of electronic devices is coupled to an upper end of the housing. For example, as discussed above, antenna  212 , and acoustic device  213  may be located externally to the housing on the upper end of the housing. Other electronic devices may also be coupled to the upper end cap, such as pressure relief valve  215 , electrical connector  216  for data transfer, and hydrophone  214 . Such components are well known in the art. One or more devices may also be located on lower end  221  of the housing. As illustrated in  FIG.  2 C , release assembly  223  may be located on the lower end of the tubular housing, which may be coupled to an anchor weight (not shown). As detailed herein, release assembly  223  is configured to release a directly or indirectly coupled device, such as an anchor or tether. 
       FIGS.  3 A- 3 B  illustrate an internal configuration of one embodiment of the autonomous seismic node from  FIGS.  2 A- 2 C .  FIGS.  3 A and  3 B  illustrate an internal side view and perspective view, respectively, showing upper end cap assembly  311  and lower end cap assembly  321  of node  300 , as well as the remainder of the internal components. Similar to prior figures, lower cap assembly  321  houses geophone sensors  341  and main battery support assembly  351  (which houses the batteries) and release mechanism assembly  371 . As illustrated, there is a sizeable open space section  361  between the upper end cap assembly and the lower end cap assembly, which provides internal volume and buoyancy for the seismic node. Each of these components will be discussed in more detail in the remaining figures. As illustrated in  FIG.  3 B , the seismic node  300  and seismic node housing  301  comprises internal support structure  331 , to which internal components can be coupled within the seismic node housing. The internal support structure can be metallic or non-metallic, and may comprise one or more vertical sections extending the length of seismic node  300 . In one embodiment, node housing  301  slides over support structure  331  and may be fastened, or otherwise mechanically coupled, to support structure  331 . Node housing  301  may be substantially cylindrical and/or tubular, and may be formed of metallic or non-metallic material. In one embodiment, the lower and upper end caps are screwed and/or coupled to the ends of node housing  301 , thereby forming seismic node  300 . 
     In one embodiment, the node is designed to keep the center of buoyancy high in the seismic node and the center of gravity low. In this embodiment, the center of gravity (COG) is below the center of buoyancy (COB). In one embodiment, a positive buoyancy chamber is designed in the upper section of the node, while the battery packs and geophones are positioned in the bottom of the node. In one embodiment, the geophones are designed as close to the lower end cap as possible. In one embodiment, the geophones are velocity sensors, and the further away from the pivot point of the node, the larger the generated signal as a result of inadvertent movement, which could negatively impact the fidelity of the intended signal. Having the COB located above the COG ensures that the node descends the water column as vertically as possible such that the upper section of the node faces towards the water surface or sky during descent. The same trait is preferred when the node is released from the seafloor. When the nodes surfaces to the ocean surface, the wireless transponder located on the top cap should have a clear, un-obstructed view of the sky. The farther the COB is away from the COG, the more stable the node becomes. In one embodiment, the node&#39;s design and shape allows the nope to remain substantially vertical in the ocean bottom and near the ocean surface, which facilitates methods for the automated recovery of the nodes. 
     In one embodiment, the seismic node of  FIGS.  2 A and  3 A  may float and/or be offset from the seabed and still record seismic signals based on water coupling between the seismic sensor and the seabed, such as that illustrated in  FIGS.  1 A and  1 B . In other embodiments, the seismic node (such as seismic node  300 ) may be coupled to the seabed for traditional  4 C recording by attaching a node base to the bottom end of the tubular housing, which also acts as an anchor to assist in free fall. A wide variety of seabed coupling devices may be used. These seabed coupling devices may be a shaft, spear, or other penetrating device (see  FIG.  4 A- 4 B ), while in other embodiments it may be a plate or base (see  FIGS.  5 A- 5 C and  6 A- 6 B ). The coupling devices can be mechanically coupled to the bottom of the node housing by a variety of mechanisms, including by a screw or other fastener. Similar to the releasable weight mechanism  119  of  FIGS.  1 A and  1 B , the attachment of the base plate/seabed coupling device may be coupled to the same release assembly  119  or a similar release mechanism that is able to detach the seabed coupling device based on an acoustic signal and allow the seismic node to pop up and/or rise to the surface after seismic recording. The seabed coupling device also acts as a ballast weight that assists in free fall of the seismic node to the seabed. 
     In each of the embodiments illustrated in  FIGS.  4 A,  5 A, and  6 A , a seismic node  300  (substantially similar to that illustrated in  FIGS.  3 A and  3 B ), has a node housing  301  coupled to upper end cap  311  and lower end cap  321 .  FIGS.  4 A- 4 B  illustrate one embodiment of a seabed coupling device according to the present disclosure, which illustrates a pointed shaft attachment device  431  (see  FIG.  4 B ) coupled to the seismic node housing. Shaft attachment  431  comprises a plurality of vertical ribs  435  that are cut at an angle and welded to round plate  433  for increased descent speed in the water and seabed penetration. In one embodiment, the penetrating device is made of iron or another metallic component, although non-metallic components are possible.  FIGS.  5 A- 5 C  illustrate another embodiment of seabed coupling device  531  according to the present disclosure, which illustrates a plate coupled to the seismic node housing.  FIG.  5 B  illustrates plate  533  of the seabed coupling device, which may be formed of metallic or non-metallic material, and in one embodiment is made of cement. As opposed to the angled shaft of  FIG.  4 B , the plate in  FIG.  5 B  slows the descent of the seismic node in water. The plate may be coupled to the bottom of the seismic node housing via metal bracket  535  (see  FIG.  5 C ).  FIGS.  6 A- 6 B  illustrate another embodiment of seabed coupling device  631  according to the present disclosure, which illustrates a tripod plate/base coupled to the seismic node housing.  FIG.  6 B  illustrates tripod base  633 , which may be a heavy metallic (e.g., steel) material. In one embodiment, base  633  comprises angled wings or fins  635  extending from each corner of tripod base  633 . The shape of the base helps control descent speed of the seismic node through water, and the high center of balance (COB) helps to keep the trajectory vertical in the water. The wide, low base ensures the node stays upright on seabed landing. In one embodiment, the seabed coupling devices are stored separately on the back of the marine vessel and can be attached to the seismic node prior to deployment into the ocean. In one embodiment, the plates in  FIG.  5 B , the brackets in  FIG.  5 C , and/or the base in  FIG.  6 B  nest together for improved storage density on the back of the marine vessel. In one embodiment, the seabed coupling devices are made of a biodegradable material. 
       FIGS.  7 A- 7 D  illustrate one embodiment of autonomous seismic node  700  according to the present disclosure. The seismic node illustrated in  FIG.  7 A  is substantially similar to  FIGS.  2 A and  3 A , but illustrates a cage coupled to an upper endcap on the top section of the housing. As illustrated in  FIG.  7 A , seismic node  700  may comprise node housing  701  coupled to an upper endcap/section  731  and lower endcap/section  741 . Upper endcap  731  may comprise a plurality of electronic components, as illustrated in  FIG.  2 A  and other embodiments herein. Upper endcap may comprise or be coupled to cage  733 , which allows handling of the seismic and protection of the electronic components on the upper end cap assembly. Node housing  701  may comprise and/or be coupled to upper flange  711  and lower flange  721 , which allows fastening and/or coupling to the upper and lower endcaps.  FIG.  7 B  illustrates tubular housing  701 , to which an upper section  731  and lower section  741  may be coupled. In one embodiment, each of the lower and upper flanges  711 ,  721  and associated upper and lower sections/endcaps  731 ,  741  comprises a plurality of recesses  713 ,  723  that allows a separate fastening device (such as fastener/clip/wedge  751 ) to be inserted to secure the end caps to the node housing. Such clips are illustrated in more detail in  FIGS.  9 E- 9 G . In one embodiment, housing  701  is made of aluminum and has a thickness to withstand water pressures of about to 3000 meters or higher.  FIG.  7 C  illustrates the seismic node of  FIG.  7 A  with the outer housing ( FIG.  7 B ) removed to show the internal configuration of the seismic node. Such components are described elsewhere herein.  FIG.  7 D  illustrates a break-away of the interior assembly from  FIG.  7 C . The interior assembly comprises upper end cap  731  (with cage  733 ), lower cap assembly  741 , and support insert  705  comprised of two parts, first part  705   a  and second part  705   b.  In one embodiment, support insert  705  may be molded and made from a polypropylene “foam” material or similar plastic, in which different pockets or recesses are molded to receive various electronic devices, such as batteries, transponders, modems, and other electronic devices. The plastic inserts may have different chase ways for wiring. In one embodiment, support structure  705  and the void space between the internal components of node housing  701  form a positive buoyancy to the seismic node. 
       FIGS.  8 A- 8 D  illustrate one embodiment of upper end assembly  731  of the autonomous seismic node of  FIG.  7 A .  FIG.  8 A  illustrates upper end cap  801  and detachable cage  811 . Detachable lifting cage  811  protecting the upper end cap, the electronics on the upper end cap, and provides a lifting/handling point for the seismic node. In one embodiment, lifting cage  811  comprises a lower clamp assembly  813  with fastening mechanism  815 . The detachable lifting cage is discussed in more detail in reference to  FIGS.  9 A- 9 D .  FIG.  8 B  illustrates an internal configuration of upper end cap  801 .  FIG.  8 C  illustrates end cap  801  without the cage and electronic components as illustrated in  FIG.  8 A .  FIG.  8 D  illustrates end cap  801  without the cage but with the electronic components illustrated in  FIG.  8 A . In one embodiment, upper end cap  801  comprises cap  803 , which comprises a plurality of recesses or pockets  841 ,  843 ,  847  (see  FIG.  8 C ) on an upper face  840  of the end cap to receive electronic components. In one embodiment, the electronic device is placed within the recess and secured into the recess from the bottom side of the end cap. For example, antenna  823  may be inserted in recess  843 , acoustic transponder  821  may be inserted in recess  843 , and hydrophone  827  may be inserted in recess  847 . Recess  847  may be fitted with protective cap/plate  828  to protect hydrophone  847 , with side openings  848  allowing water to couple with hydrophone  847  (see  FIG.  8 D ). In one embodiment, a standard electronic connector  825  (such as a Transmark connector) may be utilized on the side of the upper end cap. Some of the electronic components that protrude from the cap assembly (such as an acoustic device or hydrophone) may have a component cage  820  that surrounds the electronic component to protect it. Such cages may be metallic or non-metallic, and may be coupled to cap  803  of end cap assembly  801 . In one embodiment, the upper end cap has a primary cage  811  and each transducer has a secondary protection cage  820 . 
     In one embodiment, upper end cap  803  can be a CNC machined component made from polymer, and may be formed by injection mold. Using a polymer based material eliminates and/or reduces corrosion issues. The upper end cap may be inserted into an open end of the seismic node housing (such as housing  701  from  FIG.  7 B ). In one embodiment, end cap assembly comprises recess  849 , which allows a separate clip or wedge or fastening mechanism to be inserted into the recess to couple the end cap to the seismic node housing (which has a corresponding recess). In one embodiment, upper end cap is coupled to the node housing via threads, but threads may not be necessary, as hydrostatic pressure in the water keeps the end caps in place with the housing. In one embodiment, two or more O-rings are placed around the end cap to help seal the end cap with the housing. Similar O-rings may be placed on a lower end cap (such as lower end cap assembly  221  in  FIG.  2 A ). All electronic devices may have a plurality (such as two) O-rings for sealing concerns. 
       FIGS.  9 A- 9 D  illustrate a cage assembly for the upper end of the autonomous seismic node of  FIG.  7 A  according to one embodiment of the present disclosure. In one embodiment, detachable cage assembly  810  acts as a protective cage as well as a lifting cage, and is substantially similar to the cage in  FIG.  8 A . Cage assembly  810  comprises protective cage  811  and clamp assembly  813  with fastening mechanism  815 . As shown in  FIGS.  9 A and  9 B , the primary protection of the upper end cap comes from a two-piece stainless steel cage. For example,  FIG.  9 B  illustrates first cage part  811   a  and second cage part  811   b,  each with a corresponding clamp portion  813   a  and  813   b.  Each half of the cage may be welded together between a cage portion and the ring portion. A plastic ring (not shown) may protect the aluminum housing/tube from the steel collar assembly. The two halves of the cage may be bolted together, as shown in  FIGS.  9 C and  9 D . Each clamp portion may have fastening mechanism  815   a  and  815   b,  which can be fastened together to secure the clamp assembly together and the clamp assembly to the seismic node housing. A plastic spacer block (item  815  in  FIG.  9 C ) helps to ensure the proper clamping force is applied. In one embodiment (see  FIG.  9 D ), an upper end of the node housing has a wider lip than the rest of the housing, which produces upper ring  812  that provides a back stop to support fastening of the upper top cap and the cage. 
       FIGS.  9 E- 9 G  illustrate the upper end of the autonomous seismic node of  FIG.  7 A  according to one embodiment of the present disclosure, which is substantially similar to end cap assembly  801  in  FIG.  8 A . As shown in  FIGS.  9 E- 9 G , in one embodiment the upper end cap assembly is fastened together via a plurality of fasteners  901 , which may be keys, clips, wedges, clips and/or dogbones. In one embodiment, clip  901  fits into a recess between housing lip  812  and upper end cap assembly  801 . As illustrated in  FIG.  9 F , cap  803  comprises a first plurality of recesses  849  ( 849   a,    849   b,  etc.), while lip  812  of the housing comprises a second plurality of recesses  816  ( 816   a ,  816   b,  etc.). A first portion of clip  901  fits within recess  849   a,  and a second portion of clip  901  fits within recess  816   a.  The plurality of clips, once installed, thereby secures the upper end cap assembly to the node housing. Likewise, similar clips and corresponding recesses can be used to couple the lower end cap assembly to the seismic node housing (see  FIGS.  10 A- 10 B ). One embodiment of the fastener clip is illustrated in  FIG.  9 G . Clip  901  may be in the shape of a dogbone or dove tail wedge with a substantially flat front face  911 . Clip face  911  may comprise screw hole  913  placed within slot  915 . In one embodiment, a single flat head screw on each clip spreads the clip (by virtue of a slot through the clip) and locks it into the matching receptacle for a tight fit. The clip has a slim profile that allows it to be positioned fully within the recess so that it does not protrude past the outer edge of the housing/endcap assembly. The clip may be made of stainless steel or a high strength polymer. 
       FIGS.  10 A- 10 F  illustrate one embodiment of a lower end of the autonomous seismic node of  FIG.  7 A . As illustrated in  FIG.  10 A , seismic node housing  1001  may have a lower flange or ring  1003  at the bottom of the tubular housing. Lower end assembly  1041  (see  FIG.  10 C ) has lower end cap flange  1042 . Flange  1042  has a plurality of recesses  1023  for fasteners. When lower end cap assembly  1041  is inserted within the bottom of seismic node housing  1001 , end cap flange  1042  abuts lower flange  1003  of the node housing (see  FIG.  10 A ). Similar to  FIGS.  9 E- 9 G , clip  1021  may be positioned in recesses  1032  to securely fasten the lower end cap assembly to the node housing (see  FIGS.  10 A and  10 B ). In one embodiment, a plurality of clips  1021  securely fasten the lower end cap assembly to a lip of the tubular housing (see  FIG.  10 A ), similar to how the upper end cap assembly is coupled to the upper section of the tubular housing (see  FIG.  9 E ). In one embodiment, threads are not utilized to insert the end caps into the node housing. In one embodiment, two or more O-rings  1015  are placed around the end cap to help seal the end cap with the housing. In one embodiment, the hydrostatic pressure helps seal the lower end cap assembly and upper end cap assembly into the housing without the need for threads. In one embodiment, an electric motor and/or release assembly  1013  (see  FIG.  10 B ) is integrated into the lower end cap assembly, which allows an anchor weight or seabed coupling device or tether to be detached from the seismic node. As shown in  FIG.  10 C  and  FIG.  10 D , the lower assembly of the seismic node is built into the lower end cap assembly. The lower assembly comprises support structure  1043  that couple the lower end cap flange  1042  to the rest of the electronic components within the lower assembly. In one embodiment, the support structure  1043  comprises four aluminum struts that hold and secure the machined plastic blocks together (see  FIG.  10 D ). In one embodiment,  FIGS.  10 E and  10 F  illustrate the support block. Battery pack system  1055  is positioned between upper block  1051  and lower block  1053 , each of which are coupled to support structures  1043 . Multiple battery sections  1055   a,    1055   b  may be utilized. Lower block  1053  serves as both the geophone block and the main battery  1055  support block. Lower block  1503  may comprise a plurality of recesses, each of which holds an electronic component, such as geophones  1061 ,  1063 , and  1065 . The support blocks permit wiring to pass between the different layers via various holes in the support blocks. The support blocks can be made of plastic and formed by injection molding techniques. 
       FIGS.  11 A- 11 B  illustrate one embodiment of an autonomous seismic node with a flotation jacket according to the present disclosure. This seismic node may be substantially similar to that described in  FIGS.  2 A,  3 A, and  7 A . In one embodiment, seismic node  1101  comprises node housing  1105 , upper end cap assembly  1121 , lower end cap assembly  1131 , detachable lifting cage  1111 , and flotation jacket  1103 . In one embodiment, flotation jacket  1103  comprises two parts that substantially enclose the seismic node housing. The flotation jacket may comprise a plurality of recesses  1102 ,  1106  in which a plurality of clamps or rings  1104 ,  1108  may be inserted to securely fasten the flotation jacket around the seismic node housing. In other embodiments, the flotation jacket may comprise more parts or just one part, in which the jacket may slip over the tubular section from one end. The flotation jacket provides additional buoyancy to the seismic node. In one embodiment, the combination of the seismic node housing and the flotation jacket is positively buoyant in water, whereas in other embodiments the combination of the seismic node housing and the flotation jacket is neutrally buoyant in water. 
       FIGS.  12 A- 12 F  illustrate multiple views of one embodiment of the autonomous seismic node from  FIGS.  11 A- 11 B  but without the flotation jacket. This seismic node embodiment may be substantially similar to that described in  FIGS.  2 A,  3 A, and  7 A . In one embodiment, seismic node  1101  comprises node housing  1105 , upper end cap assembly  1121 , and lower end cap assembly  1131 . Protective cap  1129  is fastened to the end cap assembly and helps protect the electronic components protruding from the end cap assembly. An upper flange on the seismic node housing comprises recess  1125  that is adjacent to recess  1123  on upper end cap assembly Likewise, a lower flange on the seismic node housing comprises recess  1135  that is adjacent to recess  1133  on lower end cap assembly. The recesses are configured for insertion of a clip (see  FIGS.  9 E- 9 G ) to secure the seismic node housing to the lower and upper end cap assemblies. In one embodiment, a support structure extends from the lower end cap assembly to the upper end cap assembly. In another embodiment, as shown in  FIG.  12 B , a lower support structure  1107  is coupled to the lower end cap assembly, and a separate upper support structure or electronic housing  1109  is coupled to the upper end cap assembly. Both the upper and lower sections may be coupled together separately or may fit within the node housing via fastening the end cap assemblies to the node housing. An internal buoyancy chamber exists inside the node housing, which may be simply the space between the components inside the housing. As long as the water displaced by a void section weighs more than the section itself, it may be considered a buoyancy chamber.  FIGS.  12 C and  12 D  illustrate end cap assembly  1121  with and without protective cap  1129 . As described herein, end cap assembly has flange  1122  with recess  1123 , and seismic node housing  1105  has flange  1124  with recess  1125 . When recesses  1123  and  1125  are aligned, a corresponding clip can be positioned within the recesses to secure the two flanges together. A plurality of such recesses may be positioned around the circumference of the flanges. 
       FIG.  12 B  illustrates seismic node  1101  with the seismic node housing  1105  removed for illustrative purposes. Further, as compared to  FIG.  12 A , protective block  1129  is removed from end cap assembly  1121 . Electronic components may protrude from the end cap assembly with watertight connections. For example, acoustic transponder  1141 , antenna  1143 , hydrophone  1145 , and electronic connector  1147  may be utilized, as is well known in the art. More or less electronic components may be utilized. One side of the electronic components is exposed to water and pressure conditions (which must withstand seabed depths), while the other side is within the pressurized node housing and is connected via wires to internal electronic components. For example, the seismic node may have a power system (such as battery packs), seismic sensors (such as geophones), data recorders, etc. The node may comprise one or more PCB sections  1151 , which is an electronic PCB for the data recorded and/or the acoustic system. The node may comprise support structure  1155  that is used to hold the batteries in place and to support the structure above which contains the electronic PCB section. The node may comprise geophone block  1153  which is used to hold the seismic sensors (geophones) securely within the node housing. 
     A detachable lifting cage  1111  is illustrated in  FIGS.  12 E and  12 F . This is similar to the cage illustrated in  FIGS.  9 A- 9 D . In one embodiment, cage  1111  comprises two cage sections that clamp together around a portion of the upper end cap assembly. In one embodiment, cage  1111  comprises first cage section  1113   a  which is coupled to second clamp section  1115   a  and second cage section  1113   b  which is coupled to second clamp section  1115   b.  Each clamp section is hemispherical in shape. Cage portions  1113   a  and  1113   b  provide protection to the protruding electronic components and allows a user (or robot) to handle the seismic nodes. In one embodiment, each clamp portion comprises a fastening mechanism on each end of the clamp, which is configured to attach to corresponding fastening mechanisms on the other clamp. In one embodiment, clamp fastener  1118   a  is coupled to clamp fastener  1118   b  with spacer  1117 . Ring portion  1116  may be utilized on the inside of the clamp to prevent abrasion and resultant corrosion between the metallic cage and the node housing. 
       FIG.  13    illustrates one embodiment of a storage system  1300  for a plurality of autonomous seismic nodes according to one embodiment of the present disclosure. Seismic nodes  1350  may be substantially similar to that described herein. The seismic nodes may be arranged on a plurality of racks in a plurality of rows  1311   a,    1311   b,  etc., which may be located in a standardized shipping container on the back deck of a marine vessel, which may be a 20 foot or 40 foot length container. In one embodiment, the seismic nodes are arranged horizontally within container  1301  on one or more pods. The container may have a door  1303  on one side of the container and one or more doors  1305  on the other side of the container. In one embodiment, the floor of the container comprises rollers (not shown), on which the pods of seismic devices may be rolled in and out of the container. In one embodiment, 400 nodes or more can be stored in a single container; if 1600 nodes are needed for a seismic survey, 4 containers (of 400 seismic nodes each) may be utilized on the back of the marine vessel. In one embodiment, seismic nodes are stacked 10 high by 6 wide, with each column having approximately 60 seismic nodes. In one embodiment, as illustrated in  FIG.  13   , approximately 8 columns of racks of nodes can be stored within a single container. 
     In one embodiment, disclosed is a method for deploying a plurality of autonomous seismic nodes to the seabed. In one embodiment, the method comprises providing a seismic node on a back deck of a marine vessel, coupling an anchor weight to the node housing while the seismic node is on the back deck of the marine vessel, and deploying the seismic node with the coupled anchor weight from the surface vessel to the bottom of the ocean by allowing the node to free fall and/or descend on its own to the bottom of the seabed because of the coupled anchor weight. The method may further comprise coupling the anchor weight to the bottom of the ocean and retrieving the node housing from the bottom of the ocean. In one embodiment, the method may further comprise releasing the anchor weight from the node housing based on an acoustic signal and surfacing the node housing near a surface of a body of water. In one embodiment, the seismic node is substantially similar to the nodes described herein. For example, the seismic node may comprise a pressurized node housing, wherein at least one seismic sensor, at least one data recording unit, and at least one clock are located within the pressurized node housing, wherein the node housing is substantially tubular and has a length to a diameter ratio of 4:1 or greater. 
     Many other variations in the overall configuration of the node, node housing, anchor weight, and seabed coupling device are possible within the scope of the invention. For example, the node itself may be positively buoyant by itself and/or with a buoyant flotation jacket. The node may or may not use a detachable lifting cage. All or some of the components left on the seabed may be biodegradable or environmentally friendly. The nodes may be dropped from a marine surface vessel or an underwater ROV. The diameter of the tube may range between 3″ to 12″, and the length of the tube may range from 12″ to 96″. Portions of the node may be metallic or non-metallic, including the pressurized node housing. Clips and/or fasteners may or may not be used to couple the end caps to the node housing. 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. 
     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. 
     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.