Abstract:
An aspect encompasses a method of testing a subsea umbilical where a first portion of testing is performed on the subsea umbilical, the testing comprising hydraulic testing and at least one of electrical or optical testing, and a second portion of the testing is performed independent of a diver or an ROV.

Description:
BACKGROUND 
     This specification relates to subsea control systems. 
     Subsea wellheads or trees can be operated remotely using control conduits, called umbilicals, that convey control signals, data, and operating and control fluids. In some scenarios, the functional components of subsea control systems can include umbilicals, flying leads, control modules, and the like. The functionality and integrity of the control systems can be tested to verify proper operation prior to being placed into service. 
     SUMMARY 
     This specification describes technologies relating to testing subsea umbilicals. 
     An aspect encompasses a method of testing a subsea umbilical. In the method, at least one of electric or optical testing is initiated on the subsea umbilical is performed using an umbilical testing skid residing subsea and coupled to communicate hydraulically with the subsea umbilical and at least one of electrically or optically with the subsea umbilical. Hydraulic testing is initiated on the subsea umbilical using the umbilical testing skid. Substantially the remainder of the hydraulic testing is performed with the testing skid not coupled to an ROV. 
     An aspect encompasses a system for testing a subsea umbilical. The test skid includes a hydraulic testing unit for hydraulic testing the subsea umbilical, an electrical testing unit for performing electrical testing on the subsea umbilical, and an optical fiber testing unit for performing optical fiber testing on the subsea umbilical. An umbilical coupling is in communication with the hydraulic testing unit, the electrical testing unit, and the optical fiber testing unit for communicating, apart from an ROV, between the hydraulic testing unit, the electrical testing unit, and the optical fiber testing unit and a human machine interface. A test lead coupling is provided for coupling the hydraulic testing unit, the electrical testing unit, and the optical fiber testing unit to the subsea umbilical being tested. 
     An aspect encompasses a method of testing a subsea umbilical where a first portion of testing is performed on the subsea umbilical, the testing comprising hydraulic testing and at least one of electrical or optical testing, and a second portion of the testing is performed independent of a diver or an ROV. 
     Particular implementations of the subject matter described in this specification can be implemented so as to realize one or more of the following potential advantages. The subsea umbilical test skid described here can be a stand-alone unit that can be left on the seabed, for example, for over twenty four hours. The skid can be left on the seabed even after the skid has performed a portion of the testing, for example, electrical and fiber testing, to continue logging test data. The tests can include hydraulic testing including pressure tests to measure leakage in pressurized umbilicals. The skid can perform the pressure tests for extended durations, for example, one to twenty four hours or longer and log test data during this time while being unattended by a diver or remote operating vehicle (ROV). The ability to operate unattended, apart from an ROV or a diver, can in certain instances result in potential savings of several days of attending vessel time and remote operating vehicle (ROV) attendance hours. Tests such as time domain reflectometry (TDR), optical time domain reflectometry (OTDR), and the like, can be performed remotely. Further, the components on the skid, for example, hydraulic pumps and intensifiers, can also be remotely controlled. Furthermore, the skid can be self-contained such that all fluids and pumps are on board the skid with a control umbilical, used to control the testing units of the skid, provide power to the testing units of the skid, and/or collect data from the skid, being the only component external to the skid. 
     The details of one or more implementations of the subject matter described in this specification are set forth in the accompanying drawings and the description below. Other features, aspects, and advantages of the subject matter will become apparent from the description, the drawings, and the claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic diagram showing a subsea production facility. 
         FIG. 2  is a schematic diagram showing a subsea umbilical test skid operatively coupled to a human machine interface. 
         FIG. 3  is a schematic diagram showing a hydraulic system of the subsea umbilical test skid. 
         FIG. 4  is a schematic diagram showing a coupling between a test leads and a SUTA. 
         FIG. 5  is a schematic diagram showing the multiple components included in an electrical testing unit. 
         FIG. 6  is a flowchart showing a process of deploying the DWUTS. 
         FIG. 7  is a flowchart showing a process of testing. 
     
    
    
     Like reference numbers and designations in the various drawings indicate like elements. 
     DETAILED DESCRIPTION 
     This specification describes a self-contained subsea test skid that can provide a testing solution for one or more umbilicals, for example, electro-, hydraulic-, fiber-umbilicals, and the like. As described below, the subsea test skid, that resides subsea, can be coupled hydraulically to the subsea umbilical and can be used to hydraulically test the subsea umbilical. The test skid and the subsea umbilical can additionally or alternatively be coupled electrically or optically or both. 
     The following acronyms are used with for convenience of reference when describing the skid and its surroundings. 
     
       
         
               
               
             
           
               
                   
               
             
             
               
                 CR 
                 Conductor Resistance 
               
               
                 DWUTS 
                 Deep Water Umbilical Test Skid 
               
               
                 FPSO 
                 Floating Production, Storage, and Off-loading 
               
               
                 HMI 
                 Human Machine Interface 
               
               
                 IR 
                 Insulation Resistance 
               
               
                 OTDR 
                 Optical Time Domain Reflectometry 
               
               
                 PLC 
                 Programmable Logic Controller 
               
               
                 ROV 
                 Remote Operated Vehicle, also often referred to as a subsea 
               
               
                   
                 vehicle or automated underwater vehicle 
               
               
                 SUTA 
                 Subsea Umbilical Termination Assembly 
               
               
                 TDR 
                 Time Domain Reflectometry 
               
               
                 USB 
                 Universal Serial Bus 
               
               
                   
               
             
          
         
       
     
       FIG. 1  is a schematic diagram showing a subsea production facility  100 . As described below, the subsea production facility  100  includes the DWUTS  120  that can be lowered to a location near an umbilical end termination, for example, the SUTA on skid  125 , on the seabed  107 . In some implementations, the subsea production facility  100  can include a platform  105  to which one or more production risers  110  and umbilicals  115  can be operatively coupled. The production risers and umbilicals can run from the platform  105  (or FPSO) at sea level  103  to a manifold and SUTA, respectively, on skid  125  at seafloor  107 . The manifold on skid  125  can include control modules with which the manifold can be controlled. Satellite wells, each having production trees, for example, tree  130 , tree  135 , and tree  140 , can be operatively coupled to the manifold by umbilicals  160 ,  165 ,  170 . Production lines  145 ,  150 , and  155  can transport production (i.e., reservoir fluids), from the satellite wells (i.e., trees  130 ,  135 ,  140 ) to the manifold and the production riser  110  can transport the production from the manifold to the platform  105 . 
     While the production lines can transport production, the umbilicals can transport electric power, control signals, hydraulic control fluids, and the like between the trees  130 ,  135 , and  140 , the SUTA on skid  125  and the platform  105 . In some implementations, an umbilical  118  operatively couples the platform  105  and the DWUTS  120  that is configured to perform tests described below. As described later, the DWUTS  120  can be operatively coupled to the SUTA via one or more test leads  117  (similar to a subsea umbilical) and to a HMI through umbilical  118  or through an ROV (which has its own umbilical). The test leads  117  can be configured to transport fluids and communicate data, testing, and control signals between the DWUTS  120  and the umbilicals  115 ,  160 ,  165 , and  170  via the SUTA. Using the HMI, an operator can control the DWUTS  120  to perform testing on the umbilicals  115 ,  160 ,  165 , and  170 . The testing can include one or more or all of hydraulic testing, electrical testing and/or optical testing. In some scenarios, initiating one or more of the hydraulic testing, electrical testing and/or the optical testing can employ an ROV or a diver. 
     The umbilicals  160 ,  165 , and  170  are, for example, static umbilicals that couple the DWUTS  120  and the production trees  130 ,  135 , and  140 , respectively. As described with reference to  FIG. 2 , the umbilicals can be tested in their final position on the seabed  107  utilizing the DWUTS  120 . 
     In certain instances, the DWUTS  120  can be left unattended, without and apart from an ROV or diver, while some or all of the testing is performed. In some instances, once testing has been initiated, the DWUTS  120  can be left unattended and can be operate to log test data and/or complete one or more tests without and apart from a coupled or attendant ROV, attendant diver or control vessel. In some scenarios, an ROV, that is initially coupled to or attendant to the DWUTS  120 , can initiate testing (one or more tests and/or a sequence of tests) utilizing the DWUTS  120  and/or can remain and assist in performing a portion of the testing. Prior to performing another portion or the remainder of the testing, the ROV can be uncoupled from and/or leave the DWUTS  120  and fly off. The DWUTS  120  can then perform a portion or the remainder of the testing without or apart from the ROV. In certain instances, the ROV can be coupled to or attendant to the DWUTS  120  while some testing is initiated and completed and other testing is initiated but not completed. For example, the ROV may be coupled to or attendant to the DWUTS  120  while the hydraulic testing is initiated and electric and/or optical testing is initiated, and while the electric and/or optical testing is completed, but leave before the hydraulic testing is completed. The remainder of the hydraulic testing would then be completed without the ROV. Similarly, in scenarios in which a diver initiates the DWUTS  120  to perform testing, the diver can leave the DWUTS  120  unattended after the initiating, and the DWUTS  120  can perform a portion or the remainder of the testing unattended. In the context of hydraulic pressure testing, in certain instances, initiating may include flushing and pressurizing the umbilical with test liquid or gas and/or other initiating. The ROV and/or diver may leave while the leakdown of testing fluid is logged over a period of one to 24 hours or longer. 
     Once the desired testing has been completed, or at another time, the DWUTS  120  can be retrieved to the surface or used in other operations. 
       FIG. 2  is a schematic diagram showing a subsea umbilical test skid (DWUTS  120 ) operatively coupled to a human machine interface (HMI)  230 . The DWUTS  120  includes multiple components, including one or more of: a hydraulic testing unit  210  having pumps, motors and intensifiers, and configured to perform pressure, flow tests, and the like; an electrical testing unit  215  configured to perform IR, CR, TDR tests, and the like, or an optical fiber test unit  220  configured to perform OTDR tests, and the like; or a power supply  205  (e.g., battery). The DWUTS  120  further includes a data logger  225  that can be operatively coupled to one, some or all of the test units and can be configured to receive and store the data measured by the test units. In some implementations, the data logger  225  can include computer-readable and computer-searchable data storage devices, for example, hard disks, and the like, on which the data logger  225  can store the measured data. For example, the umbilical  115 ,  160 ,  165 , and  170  and the testing units are coupled to transmit testing data and signals between each other. The data logger  225  can receive the test data and signals, and in some implementations, additionally process and store the test data and signals. 
     The umbilical  118  between the DWUTS  120  and HMI  230  can connect at an umbilical coupling  235  that communicates between the testing units installed on the DWUTS  120  and the HMI  230 . In some implementations, the umbilical  118  that couples the umbilical coupling  235  and the HMI  230  can be adapted to communicate power, data, and control signals with the DWUTS  120 . The HMI  230  can be located topside, for example, on or adjacent to the platform  105 . Alternatively, the HMI  230  can be at a location that is separate from the platform  105 , for example, on another vessel. Power and/or control signals can be transmitted to the DWUTS  120 , for example, from the HMI  230  and/or from other sources, through the umbilical  118 . In some implementations, an ROV operatively couples the HMI  230  to the DWUTS  120 , providing power and/or control. 
     The HMI  230  can be configured to transmit instructions to the DWUTS  120  through the umbilical  118  to cause the test units on the DWUTS  120  to perform tests, for example, on the umbilical  115 , the production trees, and the like. The DWUTS  120  can execute the tests and continue to operate the testing and/or log testing data without and apart from the ROV. Further, the HMI  230  can be operatively coupled to the data logger  225  such that the data and the signals that the data logger  225  collects are transmitted to the HMI  230  via the umbilical  118 . In some implementations, the HMI  230  can be a computer system including one or more computers with memory, configured to execute computer software instructions stored on the memory that cause the computer to perform operations. The operations can include initializing the DWUTS  120  to perform tests on the production trees and to gather data. 
     The DWUTS  120  further includes chambers  250 , each of which includes bladders and housings. The bladders are full of fluids (e.g., test fluids) when the DWUTS  120  is deployed on the seabed  107 . The hydraulic test unit  210  of the DWUTS  120  further includes a pump  255  (or pumps) for flushing and/or pressurizing the umbilicals to test pressure. The hydraulic test unit  210  can also include a manifold for switching the unit  210  between multiple hydraulic lines of an umbilical, enabling a given hydraulic test unit to test multiple hydraulic lines. In some implementations, the DWUTS  120  can initiate hydraulic testing on the umbilicals by hydraulically pressurizing the umbilical with fluid in the bladders and housings. Subsequently, the hydraulic testing unit  210  can test the umbilical for leakage. In some implementations, the pump  255  can be a piston type positive displacement type. Alternatively, or in addition, the pumps can be pressure compensated radial piston pumps or opposed double acting piston type pumps or combinations of them. To pressurize the umbilical, the pump  255  can draw fluids from the bladders in the chambers  250  and pump the fluids to the umbilicals through the test leads  117 . To do so, the test leads  117  can be operatively coupled to the manifold through an test lead coupling  247  that is adapted to couple to the manifold on skid  125 . The chambers  250  can be re-charged upon return to the surface, i.e., filled with cleaned and certified test fluid. As described previously, the DWUTS  120  can perform substantially the remainder of the hydraulic testing while not being coupled to the ROV. The remainder of the testing can include testing the umbilical for any leakage for the duration that the umbilical has been pressurized and that the DWUTS  120  is on the seabed  107  executing tests. 
       FIG. 3  is a schematic diagram showing a hydraulic test unit of the subsea umbilical test skid (DWUTS  120 ). In some implementations, the chamber  250  can be a seawater compensated tank in which test fluid is stored. For example, the chamber  250  can include a thin membrane-like container that can separate the fluid from the seawater. The DWUTS  120  can include an onboard filtration system  260  that can be operatively coupled to the pump  255  that can pull the fluid. Power for the pump  255  can be, for example, a direct hydraulic supply from an attendant ROV. Alternatively, or in addition, the power can be from a power and control line in the umbilical  118  and/or the onboard power supply  205 . A control valve  265  (or multiple control valves), included in the DWUTS  120 , can be used to control the pressure of the pump  255 . In some scenarios, the valve  265  can be preset prior to deployment at test pressures that are relevant to the system. 
     In some implementations, the DWUTS  120  can further include flow meters  270  and pressure transducers  275  that can be operatively coupled to the pump  255 . The flow meters  270  and the pressure transducers  275  can also be operatively coupled to the data logger  225 , and can be configured to transmit measured signals to the data logger  225 , the measured signals describing the flow and pressure parameters under which the pumps  255  operate. The data logger  225  can store the signals as data, which can be retrieved, for example, downloaded, when the DWUTS  120  is retrieved to the surface. Alternatively, or in addition, the data logger  225  can transmit the signals through the umbilical  118  to the HMI  230 . In this manner, the data can be reviewed in real time as the tests are progressing and can also be downloaded when the DWUTS  120  is on the seabed  107 . Responsive to the real-time review, the HMI  230  can be used to transmit instructions to regulate the operation of the pump  255  using, for example, the control valves  265 . In some implementations, the umbilical  118  can include a fiber optic cable connecting the HMI  230  and the data logger  225 , through which the logged data and the instructions can be transmitted. In this manner, a user of the HMI  230  can monitor the pressurization rate (of the umbilical  115 , for example) and the volumes, in particular, and all the tests, in general. 
     In some implementations, the umbilical  118  can include multiple fiber-optic cables to transmit the logged data and the instructions. 
     In some implementations, the DWUTS  120  can include a fluid cleanliness analyzer  280  that can be operatively coupled to the pump  255 . For example, the fluid cleanliness analyzer  280  can be incorporated into the pump discharge to check the fluid cleanliness prior to the fluid entering the umbilical  115 . In some scenarios, the analyzer  280  can transmit the measured cleanliness of the pump discharge to the HMI  230 . The HMI  230  can store a threshold cleanliness with which the HMI  230  can compare the cleanliness value transmitted by the analyzer  280 . If the threshold is satisfied, then the HMI  230  can instruct the DWUTS  120  to fill the umbilical  115  with the test fluid. For example, the threshold value can be standard cleanliness values. 
     In some implementations, a flow restricting device  285  and a control unit  290  can regulate the flow of fluids into the umbilicals  115 ,  160 ,  165  and  170 . For example, the control unit  290  can operate the flow restricting device  285  to regulate the fluid that flows into the umbilicals through the test lead  117 . The control unit  290  and the HMI  230  can be operatively coupled to receive and transmit signals to each other, for example, through fiber-optic cables included in the umbilical  117 . The fluids in the umbilicals can be released after completion of the pressure test. To do so, in some implementations, the HMI  230  can transmit instructions to the control unit  290  based upon which the control unit  290  can operate the flow restricting device  285  to release the pressure fluids from the umbilicals. In some implementations, the pressurized fluid can be released into a separate sea water compensated tank  295 . The tank  295  can be included in the DWUTS  120  or on the manifold  125  or can be located separately. 
       FIG. 4  is a schematic diagram showing a coupling between test leads  405  and a SUTA  410 . In some implementations, the test leads  405  can be connected to a termination plate  415  that matches a termination plate  420  fitted to the SUTA  410 . In some implementations, the test leads  405  can include a lead  425 , for example, a detachable lead, that includes the optical fibers and additionally power and communication cables made from copper cores, for example. The lead or leads can connect all the testing apparatus to a communications box  430  installed, for example, in the data logger  225 . Alternatively, the communications box  430  can be installed anywhere in the DWUTS  120 . The communications box  430  can be operatively coupled to the HMI  230  using techniques, for example, similar to those described previously. In some implementations, power to the testing units, for example, the electrical testing unit  215 , the optical fiber test unit  220 , and the like, can be delivered through copper power conductors in the leads described above. 
       FIG. 5  is a schematic diagram showing the multiple components included in an electrical testing unit  215 . The test units installed on the DWUTS  120  can be configured to perform one or more of the electrical tests and the optical tests. The electrical test unit  215  can include insulation resistance testers (Megaohmmeters)  505  that can perform IR tests. In some implementations, the resistance testers  505  can be battery driven and remote operated, for example, using instructions from the HMI  230 . An example of an insulation tester  505  is a Megger S1 5010. It will be appreciated that other types of insulation testers  505  can also be used. The electrical test unit  215  of the DWUTS  120  can include a switching unit for switching the testing instruments of the unit  215  between multiple electrical lines of an umbilical, enabling a given electrical test unit to test multiple electrical lines. 
     In some implementations, the electrical test unit  215  can include CR testers (ohmmeters)  510  that can perform CR tests. The CR testers  510  can be battery driven and remote operated, for example, using instructions from the HMI  230 . An example of a CR tester  510  is a XiTRON XT560. Other types of CR testers  510  can also be used. 
     In some implementations, the electrical test unit  215  can further include a time domain reflectometer  515 , which can be remotely battery driven. An example of a time domain reflectometer  515  is a Digiflex COM. Further, the optical fiber test unit  220  can include an optical time domain reflectometer  520 , for example, a remotely battery operated JDSU 6000. In some implementations, the optical time domain reflectometer  520  can test single mode fibers at several wavelengths, for example, 1310 nm and 1550 nm. Alternatively, or in addition, the reflectometer  520  can be configured to perform multi-mode fiber testing, for example, by replacing the single mode module with a multi-mode fiber module. In other implementations, the multi-mode module can be located within the housing of the reflectometer  520  and can include a switch allowing switching between modes. It will be appreciated that multiple testers can be installed in the electrical test unit  215 . Alternatively, or in addition, the testers can be installed at several positions in the DWUTS  120 . The optical test unit  220  of the DWUTS  120  can include a switching unit for switching the instruments of the unit  220  between multiple optical fibers, enabling a given optical test unit to test multiple optical fibers. 
     The electrical test unit  215 , and the units described with reference to  FIG. 2 , can be operatively coupled to the SUTA, for example, using a common test lead for testing the electrical power and communications conductors. In some implementations, the electrical test unit  215  can be operatively coupled to the HMI  230  through a relay and PLC system which can include multiple lead pins. For example, the relay system can be connected to the communications box of the DWUTS  120  allowing communications with the HMI  230  on the top side. One or more of the lead pins connect the HMI  230  to a corresponding test unit on the DWUTS  120 . A user of the HMI  230  can transmit instructions to the one or more lead pins to operate a particular test unit to perform tests. In some scenarios, the electrical test unit  215  can be connected to the common test lead using a twelve pin bulk head connector that is installed on the housing of the electrical test unit  215 . The optical fiber test unit  220  can be connected to the HMI  230  in a manner similar to the electrical test unit  215 . In some scenarios, an eight fiber connector and flying lead with an end that is suitable for the SUTA  410  can be used to connect the optical fiber test unit  220  and the SUTA  410 . 
       FIG. 6  is a flowchart showing a process  600  of deploying the DWUTS  120 . The process  600  connects leads to the skid (step  610 ). For example, the test leads include an electrical test lead and a fiber optic test lead. The leads can be connected to the skid prior to deployment or when the skid is on the sea bead, for example, by an ROV. The process  600  deploys the skid subsea (step  615 ). For example, the DWUTS  120  can be lowered to the seabed  107  by a crane or carried by an ROV. The process  600  connects the test leads to the SUTA (step  620 ). For example, the other ends of the test leads are connected to the SUTA either by an ROV or a diver depending upon the depth. 
       FIG. 7  is a flowchart showing a process  700  of testing. The process  700  executes computer instructions for testing (step  705 ). For example, the HMI  230  executes a software program that includes computer software instructions executable by one or more computers for testing the test units. The process  700  provides the available pins that can be tested (step  710 ). The process  700  receives instructions identifying the pins to be tested (step  715 ). For example, a user of the HMI  230  can set the relay system to the correct pins for the testing units to test. The process  700  provides indication that the identified pins have been aligned (step  720 ). For example, the HMI  230  can provide an indication on a user interface indicating that the pins have been aligned. Alternatively, the HMI  230  can be operatively coupled to a device that is external to the HMI  230  to provide an indication of alignment. The process  700  executes tests responsive to instructions (step  725 ). The process  700  stores test data responsive to instructions (step  730 ). For example, the test data can be stored on a storage device, for example, a USB storage device. 
     Implementations of the HMI  230  can be implemented in digital electronic circuitry, or in computer software, firmware, or hardware, including the structures disclosed in this specification and their structural equivalents, or in combinations of one or more of them. Implementations of the subject matter described in this specification can be implemented as one or more computer programs, i.e., one or more modules of computer program instructions, encoded on computer storage medium for execution by, or to control the operation of, data processing apparatus. A computer storage medium can be, or be included in, a computer-readable storage device, a computer-readable storage substrate, a random or serial access memory array or device, or a combination of one or more of them. Moreover, while a computer storage medium is not a propagated signal, a computer storage medium can be a source or destination of computer program instructions encoded in an artificially-generated propagated signal. The computer storage medium can also be, or be included in, one or more separate physical components or media (e.g., multiple CDs, disks, or other storage devices). 
     The operations described in this specification can be implemented as operations performed by a data processing apparatus on data stored on one or more computer-readable storage devices or received from other sources. 
     The term “data processing apparatus” encompasses all kinds of apparatus, devices, and machines for processing data, including by way of example a programmable processor, a computer, a system on a chip, or multiple ones, or combinations, of the foregoing The apparatus can include special purpose logic circuitry, e.g., an FPGA (field programmable gate array) or an ASIC (application-specific integrated circuit). The apparatus can also include, in addition to hardware, code that creates an execution environment for the computer program in question, e.g., code that constitutes processor firmware, a protocol stack, a database management system, an operating system, a cross-platform runtime environment, a virtual machine, or a combination of one or more of them. The apparatus and execution environment can realize various different computing model infrastructures, such as web services, distributed computing and grid computing infrastructures. 
     A computer program (also known as a program, software, software application, script, or code) can be written in any form of programming language, including compiled or interpreted languages, declarative or procedural languages, and it can be deployed in any form, including as a stand-alone program or as a module, component, subroutine, object, or other unit suitable for use in a computing environment. A computer program may, but need not, correspond to a file in a file system. A program can be stored in a portion of a file that holds other programs or data (e.g., one or more scripts stored in a markup language document), in a single file dedicated to the program in question, or in multiple coordinated files (e.g., files that store one or more modules, sub-programs, or portions of code). A computer program can be deployed to be executed on one computer or on multiple computers that are located at one site or distributed across multiple sites and interconnected by a communication network. 
     The processes and logic flows described in this specification can be performed by one or more programmable processors executing one or more computer programs to perform actions by operating on input data and generating output. The processes and logic flows can also be performed by, and apparatus can also be implemented as, special purpose logic circuitry, e.g., an FPGA (field programmable gate array) or an ASIC (application-specific integrated circuit). 
     Processors suitable for the execution of a computer program include, by way of example, both general and special purpose microprocessors, and any one or more processors of any kind of digital computer. Generally, a processor will receive instructions and data from a read-only memory or a random access memory or both. The essential elements of a computer are a processor for performing actions in accordance with instructions and one or more memory devices for storing instructions and data. Generally, a computer will also include, or be operatively coupled to receive data from or transfer data to, or both, one or more mass storage devices for storing data, e.g., magnetic, magneto-optical disks, or optical disks. However, a computer need not have such devices. Devices suitable for storing computer program instructions and data include all forms of non-volatile memory, media and memory devices, including by way of example semiconductor memory devices, e.g., EPROM, EEPROM, and flash memory devices; magnetic disks, e.g., internal hard disks or removable disks; magneto-optical disks; and CD-ROM and DVD-ROM disks. The processor and the memory can be supplemented by, or incorporated in, special purpose logic circuitry. 
     To provide for interaction with a user, implementations of the subject matter described in this specification can be implemented on a computer having a display device, e.g., a CRT (cathode ray tube) or LCD (liquid crystal display) monitor, for displaying information to the user and a keyboard and a pointing device, e.g., a mouse or a trackball, by which the user can provide input to the computer. Other kinds of devices can be used to provide for interaction with a user as well; for example, feedback provided to the user can be any form of sensory feedback, e.g., visual feedback, auditory feedback, or tactile feedback; and input from the user can be received in any form, including acoustic, speech, or tactile input. In addition, a computer can interact with a user by sending documents to and receiving documents from a device that is used by the user; for example, by sending web pages to a web browser on a user&#39;s client device in response to requests received from the web browser. 
     While this specification contains many specific implementation details, these should not be construed as limitations on the scope of any inventions or of what may be claimed, but rather as descriptions of features specific to particular implementations of particular inventions. Certain features that are described in this specification in the context of separate implementations can also be implemented in combination in a single implementation. Conversely, various features that are described in the context of a single implementation can also be implemented in multiple implementations separately or in any suitable subcombination. Moreover, although features may be described above as acting in certain combinations and even initially claimed as such, one or more features from a claimed combination can in some cases be excised from the combination, and the claimed combination may be directed to a subcombination or variation of a subcombination. 
     Similarly, while operations are depicted in the drawings in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. 
     Thus, particular implementations of the subject matter have been described. Other implementations are within the scope of the following claims. For example, the DWUTS  120  can be used, without being coupled to an ROV, to monitor the assembly of umbilicals and associated systems during lay operations.