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Title:
STRUCTURAL HEALTH MONITORING OF FLEXIBLE PIPE
Document Type and Number:
WIPO Patent Application WO/2012/097241
Kind Code:
A1
Abstract:
A method to monitor the structural health of a flexible pipe including disposing one or more sensors within layers of the flexible pipe and wirelessly monitoring the one or more sensors with at least one receiver is provided. A structural health monitoring apparatus of a flexible pipe including a plurality of sensors disposed within layers of the flexible pipe and at least one receiver configured to wirelessly monitor the plurality of sensors is also provided. A method to manufacture a flexible pipe including forming the flexible pipe from a plurality of layers and disposing a plurality of sensors within the layers of the flexible pipe is provided. A composite armored flexible pipe including a tubular core, a plurality of structural layers, an outer jacket disposed external to the plurality of structural layers, at least one structural layer comprising one or more fiber reinforced tapes, and at least one sensor disposed between the tubular core and the outer jacket is also provided.

Inventors:
KALMAN MARK DOUGLAS (US)
Application Number:
PCT/US2012/021229
Publication Date:
July 19, 2012
Filing Date:
January 13, 2012
Export Citation:
Click for automatic bibliography generation   Help
Assignee:
DEEPFLEX INC (US)
KALMAN MARK DOUGLAS (US)
International Classes:
F16L11/08; F17D5/06; G01M3/16
Foreign References:
RU2390629C22010-05-27
US6491779B12002-12-10
RU2008139435A2010-03-27
GB2446670A2008-08-20
Attorney, Agent or Firm:
OSHA, Jonathan, P. et al. (909 Fannin Street Suite 350, Houston TX, US)
Download PDF:
Claims:
CLAIMS

What Is Claimed Is:

1. A method to monitor the structural health of a flexible pipe, the method comprising: disposing one or more sensors within layers of the flexible pipe; and

wirelessly monitoring the one or more sensors with at least one receiver.

2. The method of claim 1, wherein the one or more sensors are disposed between two or more layers of the flexible pipe.

3. The method of any of the preceding claims, further comprising disposing at least one transmitter within layers of the flexible pipe, wherein the at least one transmitter is in communication with at least one of the one or more sensors.

4. The method of claim 3, further comprising providing power to the at least one transmitter from at least one of the receiver and a battery.

5. The method of claim 3, wherein the at least one transmitter comprises a transceiver.

6. The method of any of the preceding claims, wherein the one or more sensors are disposed within at least one layer of the flexible pipe.

7. The method of any of the preceding claims, further comprising providing power to the one or more sensors from the at least one receiver.

8. The method of any of the preceding claims, further comprising providing power to the one or more sensors from a battery.

9. The method of any of the preceding claims, further comprising moving the at least one receiver along a surface of the flexible pipe to receive signals from the one or more sensors at multiple locations in the flexible pipe.

10. The method of any of the preceding claims, wherein the one or more sensors are configured to measure at least one of strain, pressure, and temperature.

1 1. The method of any of the preceding claims, wherein the at least one receiver comprises a transceiver.

12. A method to monitor the structural health of a flexible pipe, the method comprising: providing power to one or more transmitting sensors located within layers of the flexible pipe;

wirelessly monitoring the one or more sensors with at least one receiver.

13. The method of claim 12, further comprising wirelessly monitoring at least one of strain, pressure, and temperature.

14. The method of any of claims 12-13, further comprising moving the at least one receiver along a surface of the flexible pipe to receive signals from the one or more powered sensors at multiple locations in the flexible pipe

15. The method of any of claims 12-14, wherein the one or more sensors are disposed within at least one layer of the flexible pipe.

16. The method of any of claims 12-15, further comprising providing power to the one or more sensors from the at least one receiver.

17. The method of any of claims 12-16, further comprising providing power to the one or more sensors from a battery.

18. The method of any of claims 12-17, further comprising moving the at least one receiver along a surface of the flexible pipe to receive signals from the one or more sensors at multiple locations in the flexible pipe.

19. A structural health monitoring apparatus of a flexible pipe, the apparatus comprising: a plurality of sensors disposed within layers of the flexible pipe; and

at least one receiver configured to wirelessly monitor the plurality of sensors.

20. The apparatus of claim 19, wherein the plurality of sensors are disposed within at least one layer of the flexible pipe.

21. The apparatus of any of claims 19-20, wherein the plurality of sensors are disposed between two layers of the flexible pipe.

22. The apparatus of any of claims 19-21, wherein the at least one receiver is configured to provide power to the plurality of sensors.

23. The apparatus of any of claims 19-22, wherein the plurality of sensors are powered by batteries.

24. The apparatus of any of claims 19-23, wherein the at least one receiver is configured to move along a surface of the flexible pipe.

25. The apparatus of claim 24, further comprising at least one locomotive device to move the at least one receiver along the surface of the flexible pipe.

26. The apparatus of any of claims 19-25, wherein the receiver is external to the flexible pipe.

27. The apparatus of any of claims 19-26, wherein the receiver is within a bore of the flexible pipe.

28. The apparatus of any of claims 19-27, wherein the plurality of sensors are configured to measure at least one of strain, contact pressure between adjacent layers, and inter-layer temperature.

29. The apparatus of any of claims 19-28, wherein at least one of the plurality of sensors comprises a wireless sensor.

30. The apparatus of any of claims 19-29, wherein the plurality of sensors comprises a transmitter configured to communicate wirelessly with the at least one receiver.

31. The apparatus of claim 30, wherein the transmitter is a transceiver.

32. The apparatus of any of claims 19-31, wherein the receiver is a transceiver.

33. A method to manufacture a flexible pipe, the method comprising:

forming the flexible pipe from a plurality of layers; and

disposing a plurality of wireless sensors within the layers of the flexible pipe.

34. The method of claim 33, further comprising disposing one or more of the plurality of sensors between two or more layers of the flexible pipe.

35. The method of any of claims 33-34, wherein the plurality of sensors are disposed within at least one layer of the flexible pipe.

36. The method of any of claims 33-35, further comprising disposing at least one transceiver on an external surface of the flexible pipe.

37. The method of any of claims 33-36, wherein at least one of plurality of sensors comprises a wireless sensor.

38. A flexible pipe comprising:

a tubular core;

a plurality of structural layers;

an outer jacket disposed external to the plurality of structural layers;

and

at least one wireless sensor disposed between the tubular core and the outer jacket.

39. The flexible pipe of claim 38, wherein the flexible pipe is a composite armored flexible pipe with at least one structural layer comprising one or more fiber reinforced tapes.

40. The flexible pipe of any of claims 38-39, wherein the at least one sensor is disposed within the structural layer.

41. The flexible pipe of any of claims 38-39, wherein the at least one sensor is disposed on an external surface of the at least one structural layer.

42. The flexible pipe of any of claims 38-41, wherein the at least one sensor comprises a wireless link to an external receiver.

Description:
STRUCTURAL HEALTH MONITORING OF FLEXIBLE PIPE

BACKGROUND OF THE DISCLOSURE

Field of the Disclosure

[0001] The present disclosure relates to structural health monitoring of flexible pipe, and in particular, using wireless sensors to monitor the structural health of a flexible pipe, such as an unbonded flexible pipe.

Description of the Related Art

[0002] Examples of unbonded composite flexible pipes and the manufacture thereof may be found in U.S. Patent No. 6,491 ,779 issued to Michael J. Bryant, on December 10, 2002 and entitled "Method of Forming a Composite Tubular Assembly," U.S. Patent No. 6,804,942 issued to Michael J. Bryant, on October 19, 2004 and entitled "Composite Tubular Assembly and Method of Forming Same," and U.S. Patent No. 7,073,978 issued to Michael J. Bryant, on July 1 1, 2006 and entitled "Lightweight Catenary System," the entireties of which are incorporated by reference herein.

[0003] The current methods which are used to monitor the health of a flexible pipe in service are described in Chapter 6 of UKOOA Guidance Note on Monitoring Methods and Integrity Assurance for Unbonded Flexible Pipe. MCS International Doc No. 2-1- 4-221 October 2002 - including internal and external visual inspection, pressure, temperature, and bore fluid testing and monitoring, in-line coupon monitoring and dielectric sensing, annulus gas monitoring and sampling, radiography, eddy current and tomography, and load, configuration, and external environment monitoring.

[0004] Only the radiography, eddy current and tomography methods described in the

UKOOA Guidance Note provide the possibility of non-destructive visual inspection of the structural layers for physical damage due to corrosion, fatigue, environmental degradation or accidental loading.

[0005] Fiber optic monitoring can be used to measure temperature or global strain range in the pipe, but requires that the fiber be terminated and monitored at the flexible pipe end fitting.

[0006] Measuring changes in structural capacity in the outer tensile reinforcement layers with fiber optic strain gauges has been successfully demonstrated as discussed in Arthur Braga, Sergio Morikawa, Carlos Camerini, Roberth Llerena: Real time continuous structural integrity monitoring of flexible risers with optical fiber sensors, Offshore Technology Conference, May 2010.

SUMMARY OF THE CLAIMED SUBJECT MATTER

[0007] In one aspect, the present disclosure relates to a method to monitor the structural health of a flexible pipe including disposing one or more sensors within layers of the flexible pipe and wirelessly monitoring the one or more sensors with at least one receiver.

[0008] In another aspect, the present disclosure relates to a method to monitor the structural health of a flexible pipeline including providing power to one or more transmitting sensors located within layers of the flexible pipe and wirelessly monitoring the one or more sensors with at least one receiver.

[0009] In another aspect, the present disclosure relates to a structural health monitoring apparatus of a flexible pipe including a plurality of sensors disposed within layers of the flexible pipe and at least one receiver configured to wirelessly monitor the plurality of sensors.

[0010] In another aspect, the present disclosure relates to a method to manufacture a flexible pipe including forming the flexible pipe from a plurality of layers and disposing a plurality of sensors within the layers of the flexible pipe.

[0011] In another aspect, the present disclosure relates to a composite armored flexible pipe including a tubular core, a plurality of structural layers, an outer jacket disposed external to the plurality of structural layers, at least one structural layer comprising one or more fiber reinforced tapes, and at least one sensor disposed between the tubular core and the outer jacket.

BRIEF DESCRIPTION OF DRAWINGS

[0012] Features of the present disclosure will become more apparent from the following description in conjunction with the accompanying drawings.

[0013] Figure 1 is an isometric view of a flexible pipe as employed by one or more embodiments of the present disclosure. DETAILED DESCRIPTION

[0014] One or more embodiments of the present disclosure allow for monitoring the structural strains and/or other structural health factors imposed on elements of a flexible pipe during service. Referring to Figure 1 , a composite armored flexible pipe 1 is shown. Although embodiments discussed herein will be in reference to an unbonded flexible pipe, those skilled in the art will appreciate that the sensors and methods disclosed herein may be used with other composite armored flexible pipe structures.

[0015] Referring initially to Figure 1 , an isometric view of one embodiment of a composite armored flexible pipe 1 is shown. A structural pipe core 2 may be helically wrapped with a first layer of composite tape stacks 4 in a first orientation and a second layer of composite tape stacks 6 which may be counter wound with respect to stacks 4 in an alternative orientation. An anti-abrasive layer 8 may be disposed between stacks 4 and stacks 6 and an anti-extrusion layer 12 may be disposed between stacks 4 and pipe core 2. The stacks 4 and 6 may form various structural reinforcement layers of the flexible pipe. For example, the stacks 4 may be composed and oriented to form a hoop strength reinforcement layer and the stacks 6 may be composed and oriented to form a tensile reinforcement layer. Further, the stacks 4 and 6 may form burst-resistant reinforcement layers or other structural layers of the flexible pipe. As shown, only two layers of composite tape stacks are shown. However, those skilled in the art will appreciate that more layers of composite tape stacks may be provided without departing from the scope of the present disclosure.

[0016] As used herein, a composite armor layer may be a tensile layer, a hoop layer, a burst layer, or other reinforcement and/or structural layer of a flexible pipe. A jacket 10 may cover the layers and elements of the flexible pipe 1 to provide external protection. Although Figure 1 depicts a relatively simple flexible composite pipe structure 1, those skilled in the art will appreciate that a flexible pipe may include additional and/or different layers, including liners, pressure armor layers, anti-wear layers, lubricating layers, tensile armor reinforcement layers, anti-extrusion layers, membranes, and/or any other layers as may be included in a composite armored flexible pipe and/or elements of flexible steel pipe without departing from the scope of the present disclosure. [0017] The layers of the composite tape stacks 4 and 6 may comprise one or more helically wrapped tapes or stacks of laminated tapes. The tapes or stacks may be made of non-metallic fiber-reinforced tapes that may be laminated and bonded together as a single structural member. The individual layers of the stacks may include UD (unidirectional) tape and/or other structural and/or reinforced tape.

[0018] One or more embodiments of the present disclosure may be used to monitor and/or inspect the layers of an unbonded flexible pipe. The pipe to be monitored and/or inspected may be in service, in offshore dynamic or static service, and/or in onshore static service. Measurements made to monitor and/or inspect for changes in structural capacity and/or layer integrity in accordance with one or more embodiments of the present disclosure may be made in situ for input to determine the remaining service life of the monitored/inspected flexible pipe or to monitor for any damage to the pipe.

[0019] As a preliminary matter, it should be understood that while one-way communications are often described as occurring between a transmitter and a receiver, one-way communications may also occur between two transceivers, wherein one transceiver acts as the transmitter and the other acts as the receiver. As such, where a transmitter or receiver is described in the context of embodiments disclosed herein, a transceiver may be used in place of either (or both) without departing from the scope of the disclosure. Additionally, where two-way communication between two regions is desired, the transmitter and receiver may both be replaced by transceivers, such that depending on configuration, communications may travel in either direction.

[0020] In accordance with one or more embodiments of the present disclosure, wireless strain gauges and/or other wireless sensors may be embedded within the layers of an unbonded flexible pipe to monitor structural health, including direct measurements of strain, interlayer pressure and temperature. Wireless sensor data may also be obtained through transmission to receivers and analyzed to determine bore and/or annulus fluid and temperature, changes in properties of non-structural layers, such as the polymer layers, and/or any other structural health factors. The wireless strain gauges and other sensors may be interrogated by receivers or receiving transceivers that may be temporarily mounted externally to the pipe, and/or translated along or near the pipe, either by remote operated vehicles (ROV's) and/or transducer rings which use gravity or a locomotive device to move the receiver or transceiver along the external diameter of the flexible pipe. Alternatively, the wireless strain gauges or sensors may be interrogated by an intelligent pig as it passes through the bore of the flexible pipe. Additionally, it should be understood that the wireless sensors may be wireless transmitters or transmitting transceivers themselves or, in the alternative, may be wired sensors in wired communication with one or more wireless transmitters (or transceivers set to transmit) internal to the pipe for communication with the wireless receivers (or transceivers set to receive) external to the pipe. As such, the sensors internal to the pipe structure may communicate (wirelessly) directly or indirectly to the receivers (or receiving transceivers) external to the pipe.

[0021] Because unbonded flexible pipe is a multi-layer construction with relatively complex stress states in combination with uncertain environments, it has been challenging to the industry to determine the degree of remaining useful life based on changes in structural integrity of a product in service. In particular, the multiple layers of helical pressure armor used for hoop strength and helical tensile armor used for both hoop strength and tensile strength may be subject to potential fatigue due to alternating stress, wear due to interlayer contact pressure in combination with relative motion between adjacent layers, and, where metallic materials are employed, corrosion due to the annulus environment. Where composite materials are employed for the structural layers, for example in DeepFlex Flexible Fiber Reinforced Pipe (FFRP), other potential degradation mechanisms are possible, such as debonding, delamination, matrix cracking, and/or stress rupture. The degradation mechanisms can lead to a gradual loss of structural integrity over time. Thus, it may be desirable to quantify changes in structural integrity of the multiple layers for flexible pipe in service.

[0022] The challenges in quantifying the changes in structural integrity are largely a result of the multiple layer construction and the difficulties in inspecting the internal layers in the flexible pipe. It has been particularly challenging to obtain data with regard to the innermost structural layers of flexible pipe. Changes in strain as a result of applied loads are a strong indication of changes in cross sectional area and/or stiffness of a structural layer which are direct indications of changes in structural integrity. The higher contact pressures in combination with the curvature changes in dynamic service may make the innermost structural layers potentially more subject to wear and fatigue than the outermost layers. Therefore being able to monitor the performance of the innermost layers is highly desirable.

[0023] Continuous fiber optic strain gauges as discussed in U.S. Patent Application

Publication No. 2010/0089478, entitled "Flexible Pipe," and European Patent Reference No. EP 1407243 61, entitled "A method of mounting a sensor arrangement in a tubular member, and use of the method," may be suitable for monitoring and inspection of the innermost layers, but they require that the fiber be continuous over the entire helical length from the point of measurement to the point of signal detection. The point of signal detection is most often at the pipe end fitting. As such, routing the fiber through the end fitting to the point of signal detection without damaging the fiber may be difficult. In addition, if the optical fiber is damaged or deteriorates anywhere along the length between the point of measurement and signal detection, the sensing system could become non-functional or provide erroneous data.

[0024] In one or more embodiments of the present disclosure wireless sensors, such as strain gauges and/or other types of sensors, may be strategically located throughout the pipe length. Further, the wireless sensors may be located in some or all of the structural layers and may be used to measure strain and/or other properties of specific layers. Multiple sensors may be employed to measure the same properties in the vicinity of the same location to improve the accuracy of the data measurement. As such, a wired or fiber optic fiber may not be necessary to monitor the status/health of the flexible pipe.

[0025] With metallic reinforced flexible pipe as described in ISO 13628-2/AP1 17J, shielding resulting from metallic materials may pose challenges to detecting signals from wireless sensors located at the innermost layers. However, with composite reinforced flexible pipe that do not shield electromagnetic waves, such as DeepFlex FFPvP, signals from the innermost layer may be received with minimal signal power and/or interference.

[0026] In one or more embodiments of the present disclosure, the wireless sensors may be employed in unbonded flexible pipe employing metallic armor. For example, the wireless sensors could be employed under the external sheath or in other positions where signal and power transmission are not shielded by the metallic armor. [0027] Wireless strain gauges and sensors are currently being employed for civil structural, aerospace, some oil and gas, and medical applications. Most commercially available sensors are relatively large for application in flexible pipe. However, smaller sensors that would be suitable are under development for example using Micro-Electro-Mechanical-System ("MEMS") technology. For example, MEMS are described in Olson et al. , Piezoresistive Strain gauges for use in Wireless Component Monitoring Systems, College of Nanoscale Science and Engineering, University at Albany, State University of New York; Leonardi et al., Soft contact lens with MEMS strain gauge embedded for intraocular pressure monitoring, TRANSDUCERS, Solid- State Sensors, Actuators and Microsystems, 12 th International Conference, 2003; and Structural health monitoring: the demands and challenges: proceedings of the 3 rd International Workshop on Structural Health Monitoring: the Demands and Challenges, Stanford University, Stanford, CA, September 12-14, 2001. One of the main challenges to address with wireless sensors is the power consumption. Power is often provided by miniature lithium ion batteries, as described by SMD Sensors, Microstrain, and Arms et al., Wireless Strain Sensing Networks, 2 nd European Workshop on Structural Health Monitoring, Munich, Germany, July 7-9, 2004. To extend battery life, the sensors are placed in sleep mode when they are not being interrogated, and power up only to communicate with a receiving device.

[0028] Alternatively, in one or more embodiments of the present disclosure, the sensors may not require a battery. In contrast, the interrogation device (e.g., a transceiver operating in two-way communications mode to transmit power signals and receive measurement signals) may transmit power to a miniature capacitor built into the sensor. The capacitor may be sized so that the sensor (e.g., a transceiver set to receive power signals and transmit measurement signals) may have sufficient power to make a measurement and transmit the measurement back to the transceiver in the interrogation device.

[0029] Numerous small and low cost sensors may be built into the flexible pipe structure. In critical areas of dynamic risers, such as in high curvature range areas at the top or near the touchdown point, a higher density of sensors may be installed.

[0030] Both thin film sensors and thin film miniature capacitors are available and/or under development. Thus, the sensors may be adhered to individual armor spirals and for thermoplastic sheaths without causing diameter and/or wall thickness variations in the flexible pipe structure.

[0031] The sensors may be installed on the layers using suitable adhesives. An automated system for placing the sensors at specified locations may be used during the flexible pipe manufacturing process. Accordingly, a systematic, consistent, and efficient means of sensor installation may be employed.

[0032] Alternatively, thin film sensors may be integrated into a tape layer that is either wound helically on the pipe, or the tape could be one of a tape layer forming a reinforcement layer or stack in a composite armored flexible pipe such as DeepFlex FFRP.

[0033] Sensors may be employed to measure strain in any of the principal directions, contact pressure between adjacent layers, inter-layer temperatures, and/or other properties that affect structural capacity and/or layer integrity.

[0034] While the disclosure has been presented with respect to a limited number of embodiments, those skilled in the art, having benefit of this disclosure, will appreciate that other embodiments may be devised which do not depart from the scope of the present disclosure. Accordingly, the scope of the invention should be limited only by the attached claims.