WO2015036871A2 - Method of testing a subsea pipe segment bore for solids - Google Patents

Method of testing a subsea pipe segment bore for solids Download PDF

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Publication number
WO2015036871A2
WO2015036871A2 PCT/IB2014/002657 IB2014002657W WO2015036871A2 WO 2015036871 A2 WO2015036871 A2 WO 2015036871A2 IB 2014002657 W IB2014002657 W IB 2014002657W WO 2015036871 A2 WO2015036871 A2 WO 2015036871A2
Authority
WO
WIPO (PCT)
Prior art keywords
pipe segment
vehicle
laser
hydrophone
solid deposit
Prior art date
Application number
PCT/IB2014/002657
Other languages
French (fr)
Other versions
WO2015036871A3 (en
Inventor
Robert BOZSO
Tamas BOZSO
Imre CZINKOTA
Gabor Molnar
Zsolt VARI
Peter BAJCSI
Original Assignee
Zerlux Hungary Kft.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Zerlux Hungary Kft. filed Critical Zerlux Hungary Kft.
Publication of WO2015036871A2 publication Critical patent/WO2015036871A2/en
Publication of WO2015036871A3 publication Critical patent/WO2015036871A3/en

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B08—CLEANING
    • B08B—CLEANING IN GENERAL; PREVENTION OF FOULING IN GENERAL
    • B08B9/00—Cleaning hollow articles by methods or apparatus specially adapted thereto 
    • E—FIXED CONSTRUCTIONS
    • E21—EARTH OR ROCK DRILLING; MINING
    • E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
    • E21B41/00—Equipment or details not covered by groups E21B15/00 - E21B40/00
    • E21B41/04—Manipulators for underwater operations, e.g. temporarily connected to well heads
    • E—FIXED CONSTRUCTIONS
    • E21—EARTH OR ROCK DRILLING; MINING
    • E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
    • E21B37/00—Methods or apparatus for cleaning boreholes or wells
    • E—FIXED CONSTRUCTIONS
    • E21—EARTH OR ROCK DRILLING; MINING
    • E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
    • E21B41/00—Equipment or details not covered by groups E21B15/00 - E21B40/00
    • E21B41/0007—Equipment or details not covered by groups E21B15/00 - E21B40/00 for underwater installations
    • E—FIXED CONSTRUCTIONS
    • E21—EARTH OR ROCK DRILLING; MINING
    • E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
    • E21B47/00—Survey of boreholes or wells
    • E21B47/001—Survey of boreholes or wells for underwater installation
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/62—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light
    • G01N21/71—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light thermally excited
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N25/00—Investigating or analyzing materials by the use of thermal means
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
    • G01N29/22—Details, e.g. general constructional or apparatus details
    • G01N29/225—Supports, positioning or alignment in moving situation
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
    • G01N29/22—Details, e.g. general constructional or apparatus details
    • G01N29/24—Probes
    • G01N29/2418—Probes using optoacoustic interaction with the material, e.g. laser radiation, photoacoustics
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2291/00—Indexing codes associated with group G01N29/00
    • G01N2291/02—Indexing codes associated with the analysed material
    • G01N2291/025—Change of phase or condition
    • G01N2291/0258—Structural degradation, e.g. fatigue of composites, ageing of oils
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2291/00—Indexing codes associated with group G01N29/00
    • G01N2291/26—Scanned objects
    • G01N2291/263—Surfaces
    • G01N2291/2634—Surfaces cylindrical from outside

Definitions

  • the present invention relates to the testing of subsea pipes to determine the presence or absence of deposits and blockages that may impair the flow capacity of the pipes.
  • this invention relates to testing of a subsea pipe to detect a solid deposit formed within the bore of the pipe or within connected assemblies through which fluids flow such as, for example, connected valves or pipe fittings. More specifically, this invention relates to the investigation of pipe deposits and blockages through the imposition of a change in conditions that results in a physicai change of state of solid materials formed within the bore of a pipe segment.
  • the present invention relates to the investigation of pipe deposits and blockages through the imposition of changes in the stress field of a solid deposit Stress field changes induced in the solid deposit by heating provide characteristic sound waves that can be detected and analyzed.
  • Subsea pipe systems are widely used to transport fluids from one place, such as a subsea wellhead or a marine production platform, to another place, such as a marine production platform or a terrestrial facility. Hydrates, particularly gas hydrates, are a common problem encountered by operators of subsea pipe systems. The formation of hydrates within a subsea pipe system generally occurs as a result of the presence of sufficient amounts of hydrocarbon gas, usually methane and/or ethane, in die presence of water under conditions including low temperature and high pressure. The formation of hydrates is widespread i subsea pipes that are deep within the sea where temperatures can fall to 4 °C (39 °F) or lower.
  • Hydrates may also form in and on subsea pipes in waters near the poles where seawater can remain in a liquid state at temperatures below 0 °C. Any water-containing solution with a saline concentration that is lower than the seawater may potentially freeze within the pipeline under these conditions.
  • other solids may also be deposited within an interior bore of a pipe segment and impair the flow capacity of the pipe segment. Paraffin, asphalt, ice and other solids may also accumula te within the interior bore of a pipe segment.
  • Embodiments of the method and system of the present invention may be used to detect formations of hydrates, ice, asphalt, which is a mixture of longer-chain hydrocarbons, and paraffin, which is often included within recoverable oil within the earth's crust. While the acoustic response produced by heating of asphalt, paraffin or ice are substantially weaker and less attenuated than the acoustic response produced by the heating of a hydrate deposit, these materials also respond to thermal energy by producing acoustic responses that are detectable using embodiments of the method and the system of the present invention.
  • a chemical solvent that melts a hydrate blockage or that impairs the growth or formation of hydrates may be introduced into the pipe segment or upstream from the pipe segment to remediate the blockage.
  • a chemical solvent that melts a hydrate blockage or that impairs the growth or formation of hydrates may be introduced into the pipe segment or upstream from the pipe segment to remediate the blockage.
  • WO 2013/033038 discloses a system for subsea extraction of gaseous materials from, and prevention of, hydrates.
  • This system involves the use of heaters to conventionally heat a pipe segment containing hydrates and to remove the gas molecules that physically bond with water to form hydrates under low temperature and high pressure.
  • the system requires a dual-walled pipeline and powered heaters that can be used in a submerged environment.
  • An inductive heating element is configured to inductively heat a portion of a subsea pipeline.
  • US 2013/00098625 discloses a system and method for inductively heating a subsea pipeline to remediate the formation of an obstruction within the pipeline
  • U.S. Patent Application Publication no. 20030033879 discloses a method to detect the presence or absence of a blockage in a enclosed environment which includes introducing an acoustic wave into the enclosed environment (e.g.. a pipeline), using sensors to detect the acoustic wave and. reflections of the acoustic wave that are caused by a blockage. Analyzing the acoustic wave and reflected acoustic waves enables the presence or absence of a blockage to be determined ,
  • a disadvantage of some disclosed methods is that a sensor or device must be positioned and moved inside the interior bore of the pipe segment of interest. This requirement makes the use of the method difficult, expensive and adds an element of risk.
  • Other disclosed methods can be performed from without the interior bore of the pipe segment. Some have disclosed methods for ultrasonica!ly scanning the interior bore of a pipe segment using an ultrasonic generator and an. ultrasonic detector that, is moved along the exterior surface of the pipe to "ma " the location of solid deposits within the interior bore of the pipe segment.
  • One embodiment of the present invention provides a method to detect a hydrate deposit formed within a subsea pipe segment, comprising the steps of providing a submerged remotely controllable vehicle, having a hydrophone and a laser emitting element, proximal to the subsea pipe segment,, providing, on the subsea pipe segment, a laser target exposed to the laser emitting element of the vehicle and in thermally conductive communication with an interior bore wall of the pipe segment, activating the laser emitting element of the vehicle to irradiate the laser target, disassociating a volume of hydrocarbon gas from the hydrate deposit within the pipe segment by transferring heat from the laser targei to the hydrate deposit, and detecting with the hydrophone on the vehicle an acoustic signal produced by a physical change of state of the solid hydrate, which includes a disassociation of the volume of hydrocarbon gas.
  • An embodiment of this method may additional ly include the step of providing on the vehicle a data storage medium to receive and store one or more acoustic signals detected by the hydrophone.
  • An embodiment of this method may additionally include the step of providin an umbilical having a first end coupled to a marine vessel and a second end coupled to the vehicle, and communicating the acoustic signal to the vessel.
  • An embodiment of the method may additionally include the step of repositioning the vehicle to a position proximal to second subsea pipe segment, providing on the second pipe segment, a second laser target exposed to the laser emitting element of the vehicle and in thermally conductive communication with the wall of the pipe segment, activating the laser emitting element of the vehicle to irradiate the second laser target, disassociating a volume of hydrocarbon gas from a hydrate deposit within the second pipe segment by transferring heat from the second laser target to the hydrate deposit within the second pipe segment, and detecting with the hydrophone a second acoustic signal produced by disassociation of the volume of hydrocarbon gas.
  • An embodiment of the method may include the step of providing a laser target exposed to the laser emitting element of the vehicle wherein the laser target is a portion of an ex terior surface of the pipe segment. It will be understood that the laser target may be coated or otherwise conditioned to promote the maximum, absorption of the laser light emit fed onto the laser target by the laser emitting element of the vehicle.
  • An embodiment of a system of the present invention for detecting a hydrate deposit within a subsea pipe segment comprises a submersible and remotely controllable vehicle having a laser emitting element and a hydrophone, and a laser target on an exterior surface of the pipe segment in thermally condoctsve engagement with an interior bore wall of the pipe segment, wherein positioning of the vehicle proximal to the pipe segment and irradiating of the laser target transfers energy in the form of heat to the hydrate deposit within an interior bore of the pipe segment to disassociate a hydrocarbon gas from the hydrate deposit and to produce an acoustic signal that is detectable using the hydrophone on the vehicle.
  • An embodiment of the system may further include a data storage medium on the vehicle, wherein one or more acoustic signals detected by the hydrophone are stored on the data storage medium.
  • an embodiment of the system of the present invention may further include an umbilical having a first end coupled to a marine vessel and a second end coupled to the vehicle wherein the acoustic signal detected by the hydrophone of the vehicle is communicated to the vessel through the umbilical.
  • An embodiment of the system of the present in vention ma include a laser target on an exterior surface of the pipe segment in thermally conductive engagement with an interior bote wall of the pipe segment wherein the laser target is a portion, of the exterior surface of the pipe segment,
  • embodiments of the method and system of the present invention may be used to detect the presence of a range of unwanted solid deposits formed within an interior bore of pipe segment.
  • embodiments of the method and system of the present invention may also be used to detect the presence of other solid deposits including, but not limited to, paraffin, ice and asphalt due to induced phase transitions and stress field changes occurring within the matrix of the solid deposit due to healing by impingement: of laser light on the exterior surface of the pipe segment.
  • gas hydrates produce a particularly detectable acoustic response due to the disassociation of hydrocarbon gas and the corresponding pressure transient resulting therefrom
  • mere phase transformations and/or stress field changes occurring withi the matrix of a non-hydrate solid deposit can produce detectable acoustic signals, although these may not be as attenuated or pronounced as acoustic signals resulting from the disassociation of hydrocarbon gas from a heated gas hydrate.
  • Pipe segment refers to a segment of a pipe system.
  • Pipe segment may refer to a conventional length of pipe, or to assemblies that would ordinarily be connected to and/or made a part of a pipe system. These assemblies include, but are not limited to, valves, pipe fittings, blowout preventers and branches that are fabricated and connected to the pipe system to control the flow of fluids, as with a valve or blowout preventer, or to transport fluids to, or to remove fluids from, the pipe system.
  • embodiments of the method and system of the present invention include the use of an acoustic sensor such as, for example, a hydrophone, thai is carried on the vehicle and placed within detection range of the laser target on the exterior of the pipe segment.
  • electronic conditioning of the signals detected by the acoustic sensor may include amplification, attenuation and/or filtering to remove or to cancel ambient background noise, fluid flow noise, or metal expansion noise that may otherwise occlude or impair the acoustic signal.
  • laser target may be a portion of the exterior surface of the pipe segment.
  • a “laser target” may be a highly thermally conductive and optically absorptive member coupled to the exterior surface of the pipe segment .
  • acoustic signals are generated within a solid deposit within a pipe segment by heating at least a portion of the exterior surface of the pipe segment using a laser emitting element disposed on a submersible vehicle.
  • a hydrophone on the vehicle converts the acoustic signals to electrical signals which may be processed and conditioned to reveal indications of solid deposits within the bore of the pipe segment
  • the electrical signals received from the hydrophone are either stored on a memory storage device on the vehicle or they are transmitted from the vehicle via an umbilical to a remote processor unit on a vessel (0025]
  • One embodiment of the method of detecting a solid deposit within the interior bore of a subsea pipe segment comprises providing a submersible and remotel operated vehicle, having a laser emitting element and a hydrophone, in close proximity to the subsea pipe segment, irradiating a laser target on an exterior surface of the pipe segment using the laser emitting element, heating at least a portion of the solid within the interior bore by conversion of light energy of the laser light from the laser emitting element to heat at.
  • the laser target is a portion of an exterior surface of the pipe segment.
  • the solid deposit comprises a hydrate, and detecting an acoustic signal generated as a result of one of a disassociation of gas from the solid deposit and a generation of changes in a stress field of the solid deposit comprises detecting an acoustic signal generated as a result of a disassociation of gas from the hydrate.
  • a data recording device is provided on the vehicle and connected to receive and store acoustic signals detected by the hydrophone.
  • an umbilical is provided, the umbilical having a first end coupled to a marine vessel and a second end coupled to the vehicle, the umbilical including a data conduit for transmitting acoustic signals detected b the hydrophone from the vehicle to the marine vessel.
  • an umbilical is provided, the umbilical having a first, end coupled to a marine vessel and a second end coupled to the vehicle, the umbilical including a conductor for providing electrical current to the vehicle to power a laser light generator coupled to the laser emitting element.
  • FIG, 1 illustrates an embodiment of the method and system of the present invention, for testing a subsea pipe segment by heating a laser target on the pipe segment using a laser beam emitted from a laser head on a submersible and remotely operated vehicle to induce acoustic signals that are detected using a hydrophone on the vehicle.
  • FIG. 2 illustrates waveforms detected using the hydrophone and indicating the presence of hydrates within the interior bore of the irradiated pipe segment.
  • FIG. 3 illustrates a sectioned view of the pipe segment of FIG. 1 daring irradiation of the laser target of the pipe segment by laser light.
  • a solid gas hydrate such as methane hydrate or ethane hydrate, disassociates, upon a sufficient decrease in. pressure and/or a sufficient increase in temperature, into water and hydrocarbon gas. While decreasing pressure within a pipe segment may not always be feasible, embodiments of the present invention, induce hydrate disassociation into water and hydrocarbon gas by heating a laser target on the exterior of the pipe segment using a laser. The heating of the laser target transfers heat to a portion of the interior bore of the pipe segment and to solid deposit adhered to or formed on the interior bore of the pipe segment to disassociate the hydrate into water and gas.
  • gas bubbles such as, for example, methane gas bubbles and/or ethane gas bubbles
  • the change in the physical state of the solid hydrate as it disassociates into a gas phase and a liquid phase (water) creates an acoustic signal that is primarily the result of the liberation of the gas bubbles from the hydrate.
  • the formation of the gas bubbles, and the subsequent collapse of at least some of the gas bubbles, generates acoustic waves in the interior bore of the pipe segment.
  • the acoustic waves penetrate the pipe wall and can be detected by an acoustic sensor such as, for example, a hydrophone, disposed without but proximal to the pipe segment.
  • acoustic waves may be generated as a result of the loosening of a hydrate blockage and physical displacement of a loosened blockage subject to a pressure differentia!.
  • a thin layer of liquid forms between the warmed pipe wall and the blockage due to the rapid dissipation of heat through the metal of the pipe wall and the localized onset of phase transition that starts along the interior bore wall of the pipe segment as a result of the laser impingement.
  • a pressure differential across the gas hydrate blockage would result in a sudden displacement which can generate acoustic waves.
  • the pipe wall readily conducts acoustic waves that form within the interior bore of the pipe segment, especially those that occur along the interior bore wall of the pipe segment, and the pipe wall readily channels acoustic waves through to the external surface of the pipe wall which, in turn, transfers the acoustic waves to the surrounding water.
  • the laser emitting element and/or the hydrophone may be delivered to the proximity of the pipe segment to be investigated and offloaded for operation. This offloading, and the subsequent re-loading, may be provided using a remotely controllable arm, as are known in the industry.
  • cabling between the laser emitting element and the vehicle, and/or between the hydrophone and the vehicle ca allow the laser emitting element and/or the hydrophone to be disposed closer to or even on the pipe segment during operation, to be restored to their positions on the vehicle after use.
  • FIG. 1 illustrates an embodiment of the method and system o the present invention
  • FIG. 1 illustrates a submerged pipe section 11
  • a submersible vehicle 8 having a laser emitting element 9 and a hydrophone 13 is positioned proximal to the pipe sec tion 11 of interest to enable testing of the pipe segment 11 using an embodiment of the method and system of the present invention.
  • the laser emitting element 9 of the vehicle 8 is activated to emit laser light 1.0 and to cause the laser Sight 10 to impinge on the pipe segment of interest as shown in FIG, 1, As a result of the impingement of laser Sight 10 m a laser target 12 on the pipe segment 11, light energy is converted and transferred to the pipe segment I I in the form of heat energy.
  • the laser target 12, which may be an illuminated portion of the exterior surface 15 of the pipe segment 11, is metal and is a good conductor of the heat energy transferred to the pipe segment 11.
  • At least a portion of the heat imparted to the pipe segment 11 by impingement of laser light 10 from the laser emitting element 9 of the vehicle 8 is transferred across the pipe wall 16 of the pipe segment 11 to a portion of the interior bore wall (not shown in FIG. 1) of the pipe segment 1.1. At least a portion of that ' heat is transferred to a solid deposit residing within the bore (not shown) of the pipe segment 11 and deposited on the interior bore wall of the pipe segment 11.
  • the heating of the solid will result in acoustic signals 14 relating to an induced stress field and/or physical displacement, as discussed in more detail above.
  • the solid deposit within the interior bore of the pipe segment 11 is a hydrate, such as a gas hydrate
  • the result of the heat transfer to the solid deposit will result in additional acoustic signals 14 related to the disassociation of hydrocarbon gas from the heated hydrate that is proximal to the laser target 12.
  • the physical change in state of the hydrocarbon gas liberated from the hydrate causes a substantial pressure transient thai is consistent with rapid expansion or rapid liberation of gas from a substance.
  • the acoustic signals 14 are detected by the hydrophone 13 on the vehicle 9 and analyzed for correlation to the condition of the interior bore of the pipe segment 11 of ref
  • FIG. 2 illustrates a. typical acoustic response 22 thai may be produced upon the impingement of laser light 10 impinging on a laser target 12 on a pipe segment 11 as illustrated in FIG. 1.
  • FIG. 2 is a graph 17 indicating the amplitude (y-scale) of an acoustic response 22 as sensed by the hydrophone 13 over time (x-scale).
  • An acoustic baseline 21 indicates the background noise picked up by the hydrophone 13 prior to the irradiation of the laser target 1 using the laser light 10 emitted from the laser emitting element 9 on the vehicle 8.
  • the acoustic response 22 on FIG. 2 illustrates the dramatic signal produced upon disassociation of hydrocarbon gas from a hydrate blockage occurring within a subsea pipe segment 11 irradiated using laser light 10 from a laser emitting element 9.
  • FIG. 3 il lustrates how such an attenuation of the acoustic signal 22 may occur
  • FIG, 3 illustrates a sectioned, view of the pipe segment 1 of FIG. 1 during irradiation, of the laser target 12 of the pipe segment .1.1 by laser light 10.
  • the blockage 19 may block the entire cross- section of the pipe segment 11, but only a portion of the blockage 19 is shown in FIG. 3 because only a portion of the pipe segment 11 is shown.
  • the blockage 19 is disposed within the bore 18 of the pipe segment 11.
  • a pocket 20 forms within the blockage 19 proximal to the laser target 12 and immediately opposite the pipe wall 16 from the laser target 12 due to the disassociation of the gas hydrate blockage 19 into water and hydrocarbon gas.
  • the acoustic signal may be subjected to any of a known variety of processes for filtering and/or conditioning for eliminating signal characteristics occurring due to background noise, sea noise and other unwanted influences, in one embodiment of the method and system, digitized signals are processed with appropriate algebraic methods, for example, using a Fourier analysis, to reduce, minimize or eliminate background noise.
  • a computer application may be developed for this purpose to determine the presence of the solid deposit at the given laser target 12 site from residual sound o the basis of corresponding parameters.

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Abstract

A method and system for detecting the presence of a blockage within a subsea pipe segment includes a submersible and remotely-operated vehicle having a laser emitting element and a hydrophone. The vehicle is positioned proximal to a subsea pipe segment of interest, and the laser emitting element is activated to irradiate a laser target on an exterior portion of the pipe segment. The laser light is converted to heat energy, and heat is conducted from the laser target across the pipe wall to a portion of the bore of the pipe segment. Acoustic signals are produced as a result, of one of the disassociation of gas from a portion of the solid deposit proximal to the laser target, stress cracks induced in the solid deposit and physical changes of state and physical displacement occurring within the blockage. The acoustic signals are detected by the hydrophone on the vehicle.

Description

METHOD OF TESTING A SUBSEA PI PE SEGMENT BORE FOR SOLIDS
Statement of Related. A. pp¾ ication.s
j OOi I This application depends from and claims priority to Hungarian Patent
Application Serial Number no. PI 300526 filed on 11 September 2013,
BACKGROUND
Field of the inventi n
00021 The present invention relates to the testing of subsea pipes to determine the presence or absence of deposits and blockages that may impair the flow capacity of the pipes. Specifically, this invention relates to testing of a subsea pipe to detect a solid deposit formed within the bore of the pipe or within connected assemblies through which fluids flow such as, for example, connected valves or pipe fittings. More specifically, this invention relates to the investigation of pipe deposits and blockages through the imposition of a change in conditions that results in a physicai change of state of solid materials formed within the bore of a pipe segment. Also, the present invention relates to the investigation of pipe deposits and blockages through the imposition of changes in the stress field of a solid deposit Stress field changes induced in the solid deposit by heating provide characteristic sound waves that can be detected and analyzed.
Background of the Related Art
(0003] Subsea pipe systems are widely used to transport fluids from one place, such as a subsea wellhead or a marine production platform, to another place, such as a marine production platform or a terrestrial facility. Hydrates, particularly gas hydrates, are a common problem encountered by operators of subsea pipe systems. The formation of hydrates within a subsea pipe system generally occurs as a result of the presence of sufficient amounts of hydrocarbon gas, usually methane and/or ethane, in die presence of water under conditions including low temperature and high pressure. The formation of hydrates is widespread i subsea pipes that are deep within the sea where temperatures can fall to 4 °C (39 °F) or lower. Hydrates may also form in and on subsea pipes in waters near the poles where seawater can remain in a liquid state at temperatures below 0 °C. Any water-containing solution with a saline concentration that is lower than the seawater may potentially freeze within the pipeline under these conditions. In addition to hydrates, other solids may also be deposited within an interior bore of a pipe segment and impair the flow capacity of the pipe segment. Paraffin, asphalt, ice and other solids may also accumula te within the interior bore of a pipe segment.
ji004j Embodiments of the method and system of the present invention may be used to detect formations of hydrates, ice, asphalt, which is a mixture of longer-chain hydrocarbons, and paraffin, which is often included within recoverable oil within the earth's crust. While the acoustic response produced by heating of asphalt, paraffin or ice are substantially weaker and less attenuated than the acoustic response produced by the heating of a hydrate deposit, these materials also respond to thermal energy by producing acoustic responses that are detectable using embodiments of the method and the system of the present invention.
0Θ05| It will be understood that the availability of a test to reliably detect of a solid deposit formed within an interior bore of a subsea pipe segment can be a valuable tool. An operator of a subsea pipe system that has impaired flow capacity due to the formation of solids within the interior bore of a pipe segment of the pipe system can implement remedies for the loss in flow capacity. For example, but not by way of limitation, the operator may remediate the problem by flowing warm fluids through the pipe segment. It will be understood that warm fluids may be redirected to the affected pipe segment for the purpose of thawing or melting the hydrate deposit. Alternately, a chemical solvent that melts a hydrate blockage or that impairs the growth or formation of hydrates may be introduced into the pipe segment or upstream from the pipe segment to remediate the blockage. However, in order to implement these or other methods to remediate hydrate blockages, it is important to first determine the location of the blockages within a pipe system.
10006] Others have disclosed methods of detecting the formation of hydrate deposits in subsea pipe systems. Multiphase fluid flow models have been developed for predicting or forecasting the formation of solid deposits (gas hydrates in particular). For example. 'U.S. Patent 5,550,761 discloses a method to model the stationary state and transitional states of multiphase flows. U.S. Patent 6.871, 1 18 discloses a method for the continuous detection, in pipes carrying a multiphase mixture of fluids, of thermodynamic hydrate formation conditions using a mechanistic hydrodynamic module and an integrated compositional module.
J0007| WO 2013/033038 discloses a system for subsea extraction of gaseous materials from, and prevention of, hydrates. This system involves the use of heaters to conventionally heat a pipe segment containing hydrates and to remove the gas molecules that physically bond with water to form hydrates under low temperature and high pressure. The system requires a dual-walled pipeline and powered heaters that can be used in a submerged environment. An inductive heating element is configured to inductively heat a portion of a subsea pipeline.
(0008] US 2013/00098625 discloses a system and method for inductively heating a subsea pipeline to remediate the formation of an obstruction within the pipeline,
j'0009] Other meihods al low inferring the presence of a constriction or plug on the basis of reflected acoustic waves or other fluid vibrations induced inside the pipe. For example, U.S. Patent Application Publication no. 20030033879 discloses a method to detect the presence or absence of a blockage in a enclosed environment which includes introducing an acoustic wave into the enclosed environment (e.g.. a pipeline), using sensors to detect the acoustic wave and. reflections of the acoustic wave that are caused by a blockage. Analyzing the acoustic wave and reflected acoustic waves enables the presence or absence of a blockage to be determined ,
{'00.10] A disadvantage of some disclosed methods is that a sensor or device must be positioned and moved inside the interior bore of the pipe segment of interest. This requirement makes the use of the method difficult, expensive and adds an element of risk. Other disclosed methods can be performed from without the interior bore of the pipe segment. Some have disclosed methods for ultrasonica!ly scanning the interior bore of a pipe segment using an ultrasonic generator and an. ultrasonic detector that, is moved along the exterior surface of the pipe to "ma " the location of solid deposits within the interior bore of the pipe segment. BRIEF SUMM ARY
[0011 J One embodiment of the present invention provides a method to detect a hydrate deposit formed within a subsea pipe segment, comprising the steps of providing a submerged remotely controllable vehicle, having a hydrophone and a laser emitting element, proximal to the subsea pipe segment,, providing, on the subsea pipe segment, a laser target exposed to the laser emitting element of the vehicle and in thermally conductive communication with an interior bore wall of the pipe segment, activating the laser emitting element of the vehicle to irradiate the laser target, disassociating a volume of hydrocarbon gas from the hydrate deposit within the pipe segment by transferring heat from the laser targei to the hydrate deposit, and detecting with the hydrophone on the vehicle an acoustic signal produced by a physical change of state of the solid hydrate, which includes a disassociation of the volume of hydrocarbon gas.
[0012) An embodiment of this method may additional ly include the step of providing on the vehicle a data storage medium to receive and store one or more acoustic signals detected by the hydrophone.
[00133 An embodiment of this method may additionally include the step of providin an umbilical having a first end coupled to a marine vessel and a second end coupled to the vehicle, and communicating the acoustic signal to the vessel.
[0014] An embodiment of the method may additionally include the step of repositioning the vehicle to a position proximal to second subsea pipe segment, providing on the second pipe segment, a second laser target exposed to the laser emitting element of the vehicle and in thermally conductive communication with the wall of the pipe segment, activating the laser emitting element of the vehicle to irradiate the second laser target, disassociating a volume of hydrocarbon gas from a hydrate deposit within the second pipe segment by transferring heat from the second laser target to the hydrate deposit within the second pipe segment, and detecting with the hydrophone a second acoustic signal produced by disassociation of the volume of hydrocarbon gas.
[0015] An embodiment of the method may include the step of providing a laser target exposed to the laser emitting element of the vehicle wherein the laser target is a portion of an ex terior surface of the pipe segment. It will be understood that the laser target may be coated or otherwise conditioned to promote the maximum, absorption of the laser light emit fed onto the laser target by the laser emitting element of the vehicle.
[0016] An embodiment of a system of the present invention for detecting a hydrate deposit within a subsea pipe segment comprises a submersible and remotely controllable vehicle having a laser emitting element and a hydrophone, and a laser target on an exterior surface of the pipe segment in thermally condoctsve engagement with an interior bore wall of the pipe segment, wherein positioning of the vehicle proximal to the pipe segment and irradiating of the laser target transfers energy in the form of heat to the hydrate deposit within an interior bore of the pipe segment to disassociate a hydrocarbon gas from the hydrate deposit and to produce an acoustic signal that is detectable using the hydrophone on the vehicle.
[0017] An embodiment of the system may further include a data storage medium on the vehicle, wherein one or more acoustic signals detected by the hydrophone are stored on the data storage medium.
| 00I8| Alternately or concurrently, an embodiment of the system of the present invention may further include an umbilical having a first end coupled to a marine vessel and a second end coupled to the vehicle wherein the acoustic signal detected by the hydrophone of the vehicle is communicated to the vessel through the umbilical.
[0019] An embodiment of the system of the present in vention ma include a laser target on an exterior surface of the pipe segment in thermally conductive engagement with an interior bote wall of the pipe segment wherein the laser target is a portion, of the exterior surface of the pipe segment,
{'0020] it will be understood that embodiments of the method and system of the present invention may be used to detect the presence of a range of unwanted solid deposits formed within an interior bore of pipe segment. In addition to the use of embodiments of the present invention to detect the presence of a gas hydrate deposit, embodiments of the method and system of the present invention may also be used to detect the presence of other solid deposits including, but not limited to, paraffin, ice and asphalt due to induced phase transitions and stress field changes occurring within the matrix of the solid deposit due to healing by impingement: of laser light on the exterior surface of the pipe segment. While gas hydrates produce a particularly detectable acoustic response due to the disassociation of hydrocarbon gas and the corresponding pressure transient resulting therefrom, mere phase transformations and/or stress field changes occurring withi the matrix of a non-hydrate solid deposit can produce detectable acoustic signals, although these may not be as attenuated or pronounced as acoustic signals resulting from the disassociation of hydrocarbon gas from a heated gas hydrate.
(0021] It will be understood that the term "pipe segment " as that term is used herein, refers to a segment of a pipe system. Pipe segment may refer to a conventional length of pipe, or to assemblies that would ordinarily be connected to and/or made a part of a pipe system. These assemblies include, but are not limited to, valves, pipe fittings, blowout preventers and branches that are fabricated and connected to the pipe system to control the flow of fluids, as with a valve or blowout preventer, or to transport fluids to, or to remove fluids from, the pipe system.
(§022] It will be understood that embodiments of the method and system of the present invention include the use of an acoustic sensor such as, for example, a hydrophone, thai is carried on the vehicle and placed within detection range of the laser target on the exterior of the pipe segment. It will be understood that electronic conditioning of the signals detected by the acoustic sensor may include amplification, attenuation and/or filtering to remove or to cancel ambient background noise, fluid flow noise, or metal expansion noise that may otherwise occlude or impair the acoustic signal.
|0Θ23| It will be understood that the term "laser target," as that term is used herein, may be a portion of the exterior surface of the pipe segment. Alternately, a "laser target" may be a highly thermally conductive and optically absorptive member coupled to the exterior surface of the pipe segment .
(0024] In one embodiment of the method of the present invention, acoustic signals are generated within a solid deposit within a pipe segment by heating at least a portion of the exterior surface of the pipe segment using a laser emitting element disposed on a submersible vehicle. A hydrophone on the vehicle converts the acoustic signals to electrical signals which may be processed and conditioned to reveal indications of solid deposits within the bore of the pipe segment The electrical signals received from the hydrophone are either stored on a memory storage device on the vehicle or they are transmitted from the vehicle via an umbilical to a remote processor unit on a vessel (0025] One embodiment of the method of detecting a solid deposit within the interior bore of a subsea pipe segment, comprises providing a submersible and remotel operated vehicle, having a laser emitting element and a hydrophone, in close proximity to the subsea pipe segment, irradiating a laser target on an exterior surface of the pipe segment using the laser emitting element, heating at least a portion of the solid within the interior bore by conversion of light energy of the laser light from the laser emitting element to heat at. the laser target and conduction of the beat from the laser target to the Interior bore of the pipe segment, and detecting an acoustic signal generated as a result of one of a disassociation of gas from the solid deposit and a generation of changes in a stress field of the solid deposit, i one embodiment of the method, the laser target is a portion of an exterior surface of the pipe segment. In one embodiment of the method, the solid deposit comprises a hydrate, and detecting an acoustic signal generated as a result of one of a disassociation of gas from the solid deposit and a generation of changes in a stress field of the solid deposit comprises detecting an acoustic signal generated as a result of a disassociation of gas from the hydrate. In one embodiment of the method, a data recording device is provided on the vehicle and connected to receive and store acoustic signals detected by the hydrophone. In one embodiment of the method, an umbilical is provided, the umbilical having a first end coupled to a marine vessel and a second end coupled to the vehicle, the umbilical including a data conduit for transmitting acoustic signals detected b the hydrophone from the vehicle to the marine vessel In one embodiment, of the method, an umbilical is provided, the umbilical having a first, end coupled to a marine vessel and a second end coupled to the vehicle, the umbilical including a conductor for providing electrical current to the vehicle to power a laser light generator coupled to the laser emitting element.
BRIEF DESCRIPTION OF THE APPENDED DRA WINGS
('0026] FIG, 1 illustrates an embodiment of the method and system of the present invention, for testing a subsea pipe segment by heating a laser target on the pipe segment using a laser beam emitted from a laser head on a submersible and remotely operated vehicle to induce acoustic signals that are detected using a hydrophone on the vehicle. [0027] FIG. 2 illustrates waveforms detected using the hydrophone and indicating the presence of hydrates within the interior bore of the irradiated pipe segment.
[0028] FIG. 3 illustrates a sectioned view of the pipe segment of FIG. 1 daring irradiation of the laser target of the pipe segment by laser light.
DETAILED DESCRIPTION
[0029] A solid gas hydrate, such as methane hydrate or ethane hydrate, disassociates, upon a sufficient decrease in. pressure and/or a sufficient increase in temperature, into water and hydrocarbon gas. While decreasing pressure within a pipe segment may not always be feasible, embodiments of the present invention, induce hydrate disassociation into water and hydrocarbon gas by heating a laser target on the exterior of the pipe segment using a laser. The heating of the laser target transfers heat to a portion of the interior bore of the pipe segment and to solid deposit adhered to or formed on the interior bore of the pipe segment to disassociate the hydrate into water and gas. The resulting formation of gas bubbles such as, for example, methane gas bubbles and/or ethane gas bubbles, occurs as a result of the disassociation of a portion of the hydrate deposit proximal to the heated portion of the interior bore wall of the pipe segment The gas bubbles escape the wall surface and/or the hydrate deposit and the formation, of gas bubbles from die disassociating hydrate creates a pressure transient within the pipe segment. The change in the physical state of the solid hydrate as it disassociates into a gas phase and a liquid phase (water) creates an acoustic signal that is primarily the result of the liberation of the gas bubbles from the hydrate. Some of these bubbles quickly collapse as they contact surrounding fluid, within the pipe segment and cool. The formation of the gas bubbles, and the subsequent collapse of at least some of the gas bubbles, generates acoustic waves in the interior bore of the pipe segment. The acoustic waves penetrate the pipe wall and can be detected by an acoustic sensor such as, for example, a hydrophone, disposed without but proximal to the pipe segment.
} 00303 It should be noted that other physical changes occur as a result of the disassociation of the gas from the hydrate solid. As gas hydrates are solids that strongly resemble ice, stresses are initiaiiy produced inside the ice matrix as it is heated and as it expands. These stresses often result in audible acoustic waves caused by the physical and structural changes within the gas hydrate resulting from temperature changes induced by impingement of the laser light on the laser target on the pipe segment of interest.
[0031] Other acoustic waves may be generated as a result of the loosening of a hydrate blockage and physical displacement of a loosened blockage subject to a pressure differentia!. Upon initial, heating by laser light impingement o the laser target on the pipe segment, a thin layer of liquid forms between the warmed pipe wall and the blockage due to the rapid dissipation of heat through the metal of the pipe wall and the localized onset of phase transition that starts along the interior bore wall of the pipe segment as a result of the laser impingement. It will be understood that a pressure differential across the gas hydrate blockage would result in a sudden displacement which can generate acoustic waves.
[0032] It will be understood that some of these acoustic waves will he generated by materials other than gas hydrates that solidify by freezing, as these materials undergo the same types of structural and physical changes as the gas hydrates, with the exception, of the disassociation of hydrocarbon gas that occurs in the case of gas hydrates. For these other types of solid deposits that either precipitate within a pipe segment due to freezing such as, for example, paraffin and asphalt, such freeze stresses are usually caused by an inverse effect, in other words the cubic capacity of the solid phase decreases and that is why stresses freeze. In this case, opposite displacements come about as the result of heating, their sound and vibration generating effect, however, will be identical
[0033] It will be understood that, while the acoustic waves described above occur within the interior bore of the pipe segment, the solid and incompressible nature of the pipe wall provides an excellent acoustical transmission conduit. Stated another way, the pipe wall readily conducts acoustic waves that form within the interior bore of the pipe segment, especially those that occur along the interior bore wall of the pipe segment, and the pipe wall readily channels acoustic waves through to the external surface of the pipe wall which, in turn, transfers the acoustic waves to the surrounding water. Upon detecting the acoustic vibrations of the wave using the hydrophone on the vehicle, one may establish whether or not any phase transition or displacement induced by stress field changes occurs near the wall affected by depositing when the respective pipe or assembly section is heated, i.e. whether or not there is any solid deposit bonded to the wall. {'0034] It will be understood that the laser emitting element and/or the hydrophone may be delivered to the proximity of the pipe segment to be investigated and offloaded for operation. This offloading, and the subsequent re-loading, may be provided using a remotely controllable arm, as are known in the industry. It should be noted that cabling between the laser emitting element and the vehicle, and/or between the hydrophone and the vehicle, ca allow the laser emitting element and/or the hydrophone to be disposed closer to or even on the pipe segment during operation, to be restored to their positions on the vehicle after use.
{'0035] FIG. 1 illustrates an embodiment of the method and system o the present invention, FIG. 1 illustrates a submerged pipe section 11, A submersible vehicle 8 having a laser emitting element 9 and a hydrophone 13 is positioned proximal to the pipe sec tion 11 of interest to enable testing of the pipe segment 11 using an embodiment of the method and system of the present invention.
{'0036] The laser emitting element 9 of the vehicle 8 is activated to emit laser light 1.0 and to cause the laser Sight 10 to impinge on the pipe segment of interest as shown in FIG, 1, As a result of the impingement of laser Sight 10 m a laser target 12 on the pipe segment 11, light energy is converted and transferred to the pipe segment I I in the form of heat energy. The laser target 12, which may be an illuminated portion of the exterior surface 15 of the pipe segment 11, is metal and is a good conductor of the heat energy transferred to the pipe segment 11. At least a portion of the heat imparted to the pipe segment 11 by impingement of laser light 10 from the laser emitting element 9 of the vehicle 8 is transferred across the pipe wall 16 of the pipe segment 11 to a portion of the interior bore wall (not shown in FIG. 1) of the pipe segment 1.1. At least a portion of that 'heat is transferred to a solid deposit residing within the bore (not shown) of the pipe segment 11 and deposited on the interior bore wall of the pipe segment 11.
J0037] If the solid deposit (not shown in FIG. I) within the interior bore of the pipe segment 11 is paraffin, asphalt, ice or hydrate, the heating of the solid will result in acoustic signals 14 relating to an induced stress field and/or physical displacement, as discussed in more detail above. If the solid deposit within the interior bore of the pipe segment 11 is a hydrate, such as a gas hydrate, the result of the heat transfer to the solid deposit will result in additional acoustic signals 14 related to the disassociation of hydrocarbon gas from the heated hydrate that is proximal to the laser target 12. The physical change in state of the hydrocarbon gas liberated from the hydrate causes a substantial pressure transient thai is consistent with rapid expansion or rapid liberation of gas from a substance. The acoustic signals 14 are detected by the hydrophone 13 on the vehicle 9 and analyzed for correlation to the condition of the interior bore of the pipe segment 11 of interes
f0038| FIG. 2 illustrates a. typical acoustic response 22 thai may be produced upon the impingement of laser light 10 impinging on a laser target 12 on a pipe segment 11 as illustrated in FIG. 1. FIG. 2 is a graph 17 indicating the amplitude (y-scale) of an acoustic response 22 as sensed by the hydrophone 13 over time (x-scale). An acoustic baseline 21 indicates the background noise picked up by the hydrophone 13 prior to the irradiation of the laser target 1 using the laser light 10 emitted from the laser emitting element 9 on the vehicle 8. The acoustic response 22 on FIG. 2 illustrates the dramatic signal produced upon disassociation of hydrocarbon gas from a hydrate blockage occurring within a subsea pipe segment 11 irradiated using laser light 10 from a laser emitting element 9.
j0039] It will be understood that the liberation of hydrocarbon gas from a heated gas hydrate may be attenuated or magnified by the creation of an isolated of the pocket 20 of expanding gas within the bore 18 of the pipe segment 11. FIG. 3 il lustrates how such an attenuation of the acoustic signal 22 may occur, FIG, 3 illustrates a sectioned, view of the pipe segment 1 of FIG. 1 during irradiation, of the laser target 12 of the pipe segment .1.1 by laser light 10. St will be understood that the blockage 19 may block the entire cross- section of the pipe segment 11, but only a portion of the blockage 19 is shown in FIG. 3 because only a portion of the pipe segment 11 is shown. The blockage 19 is disposed within the bore 18 of the pipe segment 11. A pocket 20 forms within the blockage 19 proximal to the laser target 12 and immediately opposite the pipe wall 16 from the laser target 12 due to the disassociation of the gas hydrate blockage 19 into water and hydrocarbon gas. The pocket 20, if it is isolated from the remainder of the bore 18 of the pipe segment 11 by the blockage 19, may attenuate the acoustic signal produced upon disassociation of the gas hydrate proximal to the laser target 19 because the pressure transient is contained by the pocket 19. It will be understood that the amplitude of the acoustic signal 22 produced upon irradiation of the laser target 12 may provide an indicator of the severity of the blockage 19,
| 04t>] The acoustic signal may be subjected to any of a known variety of processes for filtering and/or conditioning for eliminating signal characteristics occurring due to background noise, sea noise and other unwanted influences, in one embodiment of the method and system, digitized signals are processed with appropriate algebraic methods, for example, using a Fourier analysis, to reduce, minimize or eliminate background noise. A computer application may be developed for this purpose to determine the presence of the solid deposit at the given laser target 12 site from residual sound o the basis of corresponding parameters.
[0041 J Experimental testing of the method and system of the present invention were conducted in a 1,000 liter pool containing water. A gas hydrate deposit was produced within a pressurized vessel with a 20 mm thick wall, with the help of R 152 A gas. The pressurized vessel was submerged in the pool The water in the pool heated the pressurized vessel and the gas hydrate contained therein. As a result, the hydrate started to melt and to surrender gas. The gas disassociation from the hydrate produced acoustic signals that were detected using a hydrophone submerged in the pool. The acoustic signal was successfully amplified using a large bandwidth amplifier, and the output: of the amplifier was directed to a high-speed analogue to digital converter. The signal was recorded in digital form using 400 kH2 sampling while persons monitoring the test listened to the signal in real-time. The signal shape was displayed on a computer and oscilloscope, along with a Fourier-transform.
1 042] The terminolog used herei is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearl indicates otherwise, it will, be further understood that the terms "comprises'' and or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, components and/or groups, but do not preclude the presence or addition of one or more other features, integers,, steps, operations, elements, components, and/or groups thereof. The terms "preferably," "preferred, "prefer," "optional Ky' "may." and similar terms are used to indicate that an item, condition or step being referred to is an optional (not reqiiired) feature of the invention.
|0043| The corresponding structures, materials, acts, and equivalents of all means or steps plus function elements in the claims below are intended to include any structure, material, or act for performing the function in combination with other claimed elements as specifically claimed. The description of the present invention lias bee presented for purposes of illustration and description, but it is not intended to be exhaustive or limited to the invention in the form disclosed. Many modifications and variations will be apparent to those of ordinar skill in the art without departing from the scope and spirit of the invention. The embodiment was chosen and described in order to best explain the principles of the invention and the practical application,, and to enable others of ordinary skill in the art to understand the invention for various embodiments with various modifications as are suited to the particular use contemplated.

Claims

We claim:
1, A method to detect a solid deposit formed within an interior bore of a subsea pipe segment, comprising:
providing a submerged remotely controllable vehicle, having a hydrophone and a laser emitting element, proximal to the subsea pipe segment;
providing, on the subsea pipe segment, a laser target exposed to the laser emitting element of the vehicle and in thermally conductive communication with a portion of the interior bore wall of the pipe segment;
activating the laser emitting element of the vehicle to irradiate the laser target;
producing a physical change of state within the solid deposit within the interior bore of the pipe segoient by transferring heat from the laser target to the sol id deposit; and detecting with the hydrophone on the vehicle an acoustic signal produced by the physical change of state of the solid deposit.
2, The method of c laim I , farther comprising:
providing on the vehicle a data storage medium to receive and store one or more acoustic signals detected by the hydrophone.
3. The method of claim 1, further comprising:
providing a umbilical having a first end coupled to a marine vessel and a second end coupled to the vehicle; and
communicating the acoustic signal to the vessel.
4. The method of claim i , further comprising:
repositioning the vehicle to a position proximal to second subsea pipe segment;
providing on the second pipe segment a second laser target exposed to the laser emitting elemen of the vehicle and in thermally conductive communication with the wall of the pipe segment;
activating the laser emitting element of the vehicle to irradiate the second laser target; producing a change of physical state within the solid deposit within an interior bore of the second pipe segment by transferring heat from the second laser target to the solid deposit within the interior bore of the second pipe segment; and
detecting with the hydrophone a second acoustsc signal produced by the change in physical state of the solid deposit within the interior bore of the second pipe segment.
5. The method of claim 1 , wherein the laser target is a portio of an exterior surface of the pipe segment .
6. The method of claim 1, wherein the solid deposit is a gas hydrate; and
wherein the physical change of state is a disassociadon of gas from the gas hydrate.
7. A system for detecting a solid deposit within a subsea pipe segment, comprising: a submersible and remotely controllable vehicle having a laser emitting element and a hydrophone; and
a laser target on an exterior surface of the pipe segment in thermally conductive engagement with an interior bore wall of the pipe segment;
wherein positioning of the vehicle proximal to the pipe segment and irradiation of the laser target transfers energy in the form of heat to the solid deposit within an interior bore of the pipe segment to induce at least one of a change of a physical state of the solid deposit and a stress field change within the solid deposit and to thereby produce an acoustic signal that is detectable using the hydrophone.
8. The system, of claim 7, further comprising:
a data storage medium on the vehicle;
wherein the acoustic signals detected by the hydrophone are stored on the data storage medium.
9. The system, of claim 7, further comprising: an umbilical having a "first end coupled to a marine vessel and a second end coupled to the vehicle;
wherein the acoustic signal detected by the hydrophone is communicated to the vessel through the umbilical.
10. The system of claim 7, wherein the laser target is a portion of the exterior surface of the pi pe segment.
1 .1. A method of detecting a solid deposit within the interior bore of a sobsea pipe segment, co.mp.ri sing;
providing a submersible and remotely operated vehicle, having a laser emitting element and a hydrophone, in close proximity to the subsea pipe segment;
irradiating a laser target on an exterior surface of the pipe segment using the laser emitting element;
heating at least a portion of the solid within the interior bore by conversion of light energy of the laser light from the laser emitting element to heat at the laser target and conduction of the heat from the laser target to the interior bore of the pipe segment; and
detecting an acoustic signal generated as a result of one of a disassociation of gas from the solid deposit and a generation of changes in a stress field of the solid deposit.
12. The method of claim 3 1 , wherein the laser target is a portion of an exterior surface of the pipe segment.
1.3. The method of claim J 1, wherein the solid deposit, comprises a hydrate; and
wherein detectins an acoustic sienal aenerated as a result of one of a disassociation of gas from the solid deposit and a generation of changes in a stress field of the solid deposit comprises;
detecting an acoustic signal generated as a result of a disassociation of gas from the hydrate.
.1 . The method of claim 1 1. further including:
providing on ihe vehicle a data recording device connected to receive and store acoustic signals from the hydrophone.
.15. The method of claim 11 , further including:
providing an umbilical having a first end coupled to a marine vesse! and a second end coupled to the vehicle, the umbilical including a data conduit tor transmitting acoustic signals detected by the hydrophone from the vehicle to the marine vessel. . The method of claim 1 1 , further including:
providing an umbilical having a first end coupled to a marine vessel and a second end coupled to the vehicle, the umbilical including a conductor for providing electrical current to the vehicle to power a laser Sight generator coupled to the laser emitting element.
PCT/IB2014/002657 2013-09-11 2014-09-11 Method of testing a subsea pipe segment bore for solids WO2015036871A2 (en)

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN105784971A (en) * 2016-03-25 2016-07-20 大连理工大学 Experimental facility for utilizing anelastic strain recovery method for in situ analysis of aquo-complex settled layer stress state
CN106894810A (en) * 2017-02-22 2017-06-27 中国石油大学(华东) The monitoring device and method of hydrate deposition rule during the test of deep water gas well
CN107218518A (en) * 2017-04-17 2017-09-29 昆明理工大学 A kind of detection method of detection means for drain line blockage failure

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CN108130146B (en) * 2017-12-07 2020-07-21 中国科学院广州能源研究所 Gas hydrate crystal culture device

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CA2204950A1 (en) * 1997-05-09 1998-11-09 Hycal Energy Research Laboratories Ltd. Determination of phase change phenomena of matter using acoustic resonance technology (art)
HUP1200062A2 (en) * 2012-01-26 2013-09-30 Sld Enhanced Recovery Inc Houston Method for laser drilling

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN105784971A (en) * 2016-03-25 2016-07-20 大连理工大学 Experimental facility for utilizing anelastic strain recovery method for in situ analysis of aquo-complex settled layer stress state
CN106894810A (en) * 2017-02-22 2017-06-27 中国石油大学(华东) The monitoring device and method of hydrate deposition rule during the test of deep water gas well
CN107218518A (en) * 2017-04-17 2017-09-29 昆明理工大学 A kind of detection method of detection means for drain line blockage failure

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