Device for inspecting flexible ducts and method for inspecting flexible ducts

Abstract

The present invention relates to an ROV-operated device for inspecting flexible pipes used in the oil and gas field, and, more specifically, to a device capable of identifying flooded sections in the annulus of flexible pipes. The device for inspection of flexible pipelines comprises: a marinized electronic assembly; a traction and displacement system; a sensor module comprising a plurality of sensors for non-destructive testing; wherein the sensor module is connected to a radial displacement system; and at least one gripping element capable of performing vertical and horizontal rotation of the device. The invention further relates to a method for inspecting flexible pipes.

Description

[0001] DESCRIPTIVE REPORT

[0002] DEVICE FOR INSPECTION OF FLEXIBLE PIPES AND METHOD FOR INSPECTING FLEXIBLE PIPES

[0003] TECHNICAL FIELD

[0004]

[0001] The present invention belongs to the technical field of oil and gas, and more specifically, to the field of inspections in injection and production pipelines through the use of Remotely Operated Vehicles (ROVs).

[0005]

[0002] The present invention relates to a device, operated by ROV, for inspecting flexible pipelines used in the oil and gas field, and, more specifically, to a device capable of identifying flooded sections in the annulus of flexible pipelines. In addition, the invention also relates to a method for inspecting flexible pipelines.

[0006] FUNDAMENTALS OF THE INVENTION

[0007]

[0003] Flexible pipelines are used in a variety of applications, including production, injection, export and service lines, facilitating the transport of oil, gas, condensate, water and chemicals. In static applications, they function as flow lines, while in dynamic applications, they act as risers for offshore loading systems and connections between floating production facilities and subsea equipment. Flexible pipelines play a crucial role, connecting production wells to, for example, a Floating Production Storage and Offloading (FPSO).

[0008]

[0004] The main components of these flexible ducts are the casing, the inner pressure cover, the pressure and tensile armor layers, the duct annulus and the outer pressure cover.

[0009]

[0005] The annulus of the flexible pipeline is delimited by the internal and external polymeric sealing layers, where its main metallic structures are located, that is, the pressure and tension reinforcements. The pipeline annulus is a crucial area that requires monitoring.

[0006] However, the service life of these flexible pipelines is significantly affected by CO2 stress corrosion cracking (SCC-CO2). This problem arises due to the presence of water in the annular region, combined with the permeation of CO2 from fluids, creating a corrosive environment that leads to structural degradation and, eventually, rupture.

[0010]

[0007] To trigger the SCC-CO2 failure mechanism, the starting point is the presence of water inside the pipeline annulus. This water can originate from the ocean and enter through various routes, such as damage to the outer covering, assembly problems, and valve malfunctions. Flooding can also occur due to condensation from fluids passing through the pipeline. Subsequently, the ideal corrosive environment is established when the water mixes with gases, especially carbon dioxide (CO2). After this stage, chemical reactions occur, initiating corrosion of the structural layers of flexible pipelines.

[0011]

[0008] In addition to the high concentration of CO2, the severe ocean conditions also contribute to increasing the stresses applied to the flexible pipelines.

[0012]

[0009] Consequently, there is a favorable context for triggering the SCC-CO2 failure mechanism in flexible pipelines installed on FPSOs. SCC-CO2 can lead to serious consequences in flexible pipelines, ultimately culminating in their rupture.

[0013]

[0010] In order to avoid incidents with pipelines in operation, it is crucial to consider the irreparable consequences that may occur in social, environmental and economic aspects. Given the large volume of pipelines already installed in the fields, alternatives have been developed to regularly monitor and inspect flexible pipelines.

[0014]

[0011] Patent BR102018069242 discloses a flood detection system in a flexible duct from a flexible duct connector comprising an ROV comprising an arm element adapted to move an ultrasonic sensor until the ultrasonic sensor comes into contact with the flexible duct connector; and means for performing ultrasonic measurements with respect to the state of the flexible duct annulus from a chamber in the flexible duct connector in contact with the flexible duct annulus.The invention further provides a method for detecting flooding in a flexible duct from a flexible duct connector comprising the steps of: moving an ROV to a region near the flexible duct connector; actuating an ROV arm element to move an ultrasonic sensor until the ultrasonic sensor comes into contact with the flexible duct connector; and performing ultrasonic measurements with respect to the state of the flexible duct annulus from a chamber in the flexible duct connector in contact with the flexible duct annulus.

[0015]

[0012] Document BR102018075029 discloses a system that allows the detection of leaks or flooding in flexible pipeline annuli using a connector comprising: a piston and cylinder assembly interconnected by a rod to a chamber that functions as a pilot valve, connected directly to the outlet of a PSV valve of a flexible pipeline connector, into which they are fitted using a sealing system, the operation of which is controlled by commands sent to the ROV, which contains an arm and which controls the system via a manipulator. This document also describes the operating method of the device and how the results obtained lead to a pre-programmed conclusion of leak tightness or not of the annulus. Other methods foreseen were to obtain fluid samples in the annulus for subsequent analysis and to allow the removal of PSVs from the connectors.

[0016]

[0013] Finally, document US9784716 discloses a method for evaluating the condition of a tubular element comprising driving an ultrasonic probe to fire a short-pulse ultrasonic beam onto the outer surface of the tubular element and analyzing the reflected signals from the tubular element to evaluate the condition of the tubular element. The apparatus comprises an ultrasonic probe, means for driving the probe to fire a short-pulse ultrasonic beam onto the outer surface of the tubular member, and means for converting the reflected ultrasonic beam into image signals that can be analyzed to evaluate the condition of the tubular element.

[0017]

[0014] The prior art discloses devices that are capable of inspecting gas injection lines, however, they have limitations for performance in production lines. In addition, prior art devices require either a production interruption or a longer ROV usage time when inspecting flexible pipelines, leading to higher operating costs.

[0018]

[0015] One objective of the present invention is to perform the inspection of flexible pipelines without interrupting production. Another objective of the invention is to reduce the waiting time between the analysis of subsequent pipelines. An additional objective of the invention is to reduce costs when performing inspections on flexible pipelines.

[0019]

[0016] To that end, the present invention defines a device for inspection in flexible pipelines, said device operated by ROV, comprising: a marine-grade electronic assembly; a traction and displacement system; a sensor module comprising a plurality of sensors for non-destructive inspection; wherein the sensor module is connected to a radial displacement system; and at least one pan-tilt handle capable of performing vertical and horizontal rotation of the device.

[0020]

[0017] In addition, the present invention also defines a method for inspecting flexible pipelines comprising the following steps: i- lowering an ROV equipped with the inspection device to the section of the flexible pipeline to be inspected; ii- positioning the inspection device adjacent to the flexible pipeline using the ROV's robotic manipulator; iii- fixing the inspection device to the flexible pipeline using its clamping grips; iv- bringing the sensor module, comprising a plurality of sensors, close to the outer wall of the flexible pipeline; v- rotating the sensor module 360 ​​degrees along the perimeter of the cross-section of the flexible pipeline in order to acquire data from the sensors; vi- moving the inspection device along the flexible pipeline using the inspection device's traction and displacement system; vii- repeating steps ve and vii in order to acquire sufficient data for the inspection;viii- After completing data acquisition, open the fastening clamps to detach the inspection device from the flexible duct; ix- Rest the inspection device on the skid; and x- Raise the ROV to the surface.

[0021]

[0018] In this way, the ROV-operated device, which performs non-destructive testing, has the ability to inspect through the insulation layer of pipelines and, therefore, detect and locate flooded sections in the annular region of flexible production pipelines, as well as in injection pipelines, in a short period of time. The device is able to distinguish between dry and flooded annulus for different pipelines available on the market, with different thicknesses, layers and sections.

[0022]

[0019] The device uses different sensors that, when combined, enhance the inspection capability in flexible ducts, providing a better signal and resolution for inspection, allowing the range to detect metallic structures, even when there are thick layers of insulation in the ducts. Advanced sensors for non-destructive inspections are used, offering greater resolution and penetration capability even through thick layers of thermal insulation.

[0023]

[0020] The invention also has its own radial displacement system for the sensors, which allows for complete 360-degree radial displacement, with visualization and analysis of the data. This technology allows the tool to collect data at various points along the flexible duct. Thus, acquisition and visualization are done in real time. Subsequently, the data are easily analyzed, that is, the determination of whether the annulus is dry or flooded can be made more quickly than is possible with prior art technology.

[0024]

[0021] The device also includes a traction and displacement system along the flexible duct which, combined with the other features, makes it possible to maximize the area to be inspected, allowing the tool to reach any regions and points of interest for inspection in the flexible ducts in operation. In addition, it also includes a pan-tilt grip for ROVs, capable of performing vertical and horizontal rotation of the device, thus avoiding the need to move the ROV manipulator.

[0025]

[0022] The pan-tilt handle allows the inspection device to be positioned in flexible pipelines in any subsea position, namely horizontal (riser), vertical flowline or any intermediate position between vertical and horizontal.

[0026]

[0023] The device also has at least one high-definition video camera, at least one high-luminescence spotlight, and at least one internal camera, which assist in coupling the sensors to the flexible duct. These elements help maximize the flexibility of the device and can optimize the detection of annular flooding in flexible ducts used in deepwater production and injection.

[0027]

[0024] The device also includes a visual monitoring system and electronic sensors to track its own integrity. This allows for real-time monitoring of the coupling, tightness, and internal temperature conditions of sealed vessels and electronic control systems, as well as control of the section inspected by the tool.

[0028]

[0025] The device also features the use of a digital twin developed to numerically simulate the behavior of flexible sections in a field environment, predicting ultrasonic behaviors and classification patterns for a sample with a dry or flooded annular space.

[0029]

[0026] The device of the present invention is capable of fixing and inspecting ducts of different external diameters, ranging from 200mm to 420mm, without the need to change parts.

[0030]

[0027] Additionally, the device comprises a marine-grade electronic assembly with a 256-channel ultrasound sampling rate, which makes it capable of inspecting the entire circumference of a pipeline, with a resolution of 1 degree, in less than 1 minute.

[0031]

[0028] Prior art devices require the replacement of parts as varying external diameters are inspected, which significantly increases inspection time. Therefore, the present invention provides inspection without the need to interrupt operations, since it is not necessary to lift the device to change parts each time a pipe with a different diameter or section is to be inspected. This makes the inspection process much faster than when using prior art devices.

[0032] DESCRIPTION OF THE FIGURES

[0033]

[0029] Figure 1 is a perspective view of the inspection device, attached to a flexible duct to be inspected, according to a preferred embodiment of the invention.

[0034]

[0030] Figure 2 is an exploded perspective view in which the floats have been moved so that the internal elements of the device can be visualized for inspection, according to a preferred embodiment of the invention.

[0035]

[0031] Figure 3 is a bottom view of the inspection device, with the X and Y planes represented, according to a preferred embodiment of the invention.

[0036]

[0032] Figure 4 is a perspective view of the inspection device, representing the elements of the lower part, according to a preferred embodiment of the invention.

[0037]

[0033] Figure 5 is a perspective view of the ROV and skid-mounted inspection device assembly, according to a preferred embodiment of the invention.

[0038] DETAILED DESCRIPTION OF THE INVENTION

[0039]

[0034] The following detailed description refers to figures in which embodiments of the present invention are represented, by way of non-limiting illustration. These embodiments are described in such a way as to allow a person skilled in the art to reproduce their results. Other embodiments are possible and can be carried out without departing from the spirit and scope of the present invention. The following detailed description should therefore not be understood in a restrictive or limiting manner.

[0040]

[0035] Figure 1 shows an embodiment of the invention and represents the inspection device (100) attached to a flexible duct (1). In this representation, the device (100) comprises a two-part float (101), which acts in supporting the weight of the device (100) when in underwater locations. The float (101) of the present invention is not limited to a two-part model, which is a preferred embodiment of the invention. The float (101) may be a single piece or formed by more than two mountable or interlockable parts, or it may be any type of float that a person skilled in the art can identify as compatible with the inspection device (100).

[0041]

[0036] Figure 2 shows the inspection device (100) comprising at least one pan-tilt handle (120), which is responsible for promoting the vertical and horizontal rotation of the tool. The pan-tilt handle (120) comprises at least two hydraulic actuators, through which the vertical and horizontal rotations are performed. The horizontal and vertical rotations are performed in the angular range of 0 to 180°.

[0042]

[0037] The inspection device (100) further comprises at least one side handle (121) which can serve as a lifting point for the inspection device (100). Additionally, the inspection device (100) may also comprise a rear handle which serves as a fixing point for a hydraulic umbilical (not shown). The umbilical is formed by a plurality of hoses, and more specifically, by 8 hydraulic hoses, two for each function: 1- opening and closing of the fixing jaws (140); 2- approach and retraction of the sensor module (131); 3- pan / tilt handle (120); 4- tilt / inclination of the pan / tilt handle (120). However, it should be noted that the number of hoses may vary depending on the number of hydraulic systems that require fluid supply for their full operation.

[0043]

[0038] The inspection device (100) further comprises at least one 4-function hydraulic hot-stab (122), which is a hydraulic connector of the umbilical with the inspection device (100). The hydraulic hot-stab (122) can be connected and disconnected from the inspection device (100) in emergencies, such as, for example, in case of failure of the device (100) where it becomes stuck to the duct (1) and the ROV (300) needs to be disconnected.

[0039] With reference to Figure 3, the inspection device (100) further comprises a sensor module (131) including a plurality of non-destructive inspection sensors of at least one type among, but not limited to, phased array and single-crystal ultrasound sensors, preferably two phased array sensors and four single-crystal sensors.

[0044]

[0040] The inspection device (100) further comprises a radial displacement system, which allows the sensor module (131) to scan the entire perimeter of the longitudinal section of the flexible duct (1) in which the inspection device (100) is located. The radial displacement system comprises at least one electric motor (130) for rotating the sensor module (131), a gearbox (132) coupled to the electric motor (130) and a handle for manual rotation (126), which can also be actuated by the robotic manipulator (310) of the ROV (300).

[0045]

[0041] Additionally, the sensor module (131) is also connected to at least one hydraulic actuator (not shown) that acts in the radial direction, through which the sensor module (131) can be moved radially so that the plurality of sensors can approach the outer wall of the flexible duct (1).

[0046]

[0042] Figure 3 further shows the clamping jaws (140) which are formed by at least one clamping arm (141), a rotating wheel (142), and their movement is actuated by at least one hydraulic actuator, more preferably at least two hydraulic actuators, located on the clamping arm (141). The clamping arm (141) is movable in the plane perpendicular to the plane formed by the X and Y axes shown in Figure 3. This configuration allows the inspection device (100) to be adjusted to flexible ducts of different external diameters and, more specifically, with external diameters in the range of 200mm to 420mm.

[0043] The inspection device (100) comprises a digital encoder installed on the electric traction motor (110) to measure the distance traveled by the device (100) along the flexible duct (1).

[0047]

[0044] Figure 4 shows a preferred embodiment of the inspection device (100), comprising an electric traction motor (110), a traction conveyor (111) and a gearbox (112). The inspection device (100) is moved along the flexible duct (1) by means of the traction conveyor (111). The traction conveyor (111) is driven by the gearbox (112), which receives torque directly from the traction motor (110). The assembly comprising the traction motor (110), traction conveyor (111), gearbox (112) and a traction motor control electronics defines the traction and displacement system.

[0048]

[0045] The traction and displacement system of the inspection device (100) allows the device (100) to autonomously inspect different sections of flexible ducts (1), since the device (100) can move along flexible ducts (1) without the aid of the ROV (300). The control of the inspected section by the device (100) is performed based on data from the digital encoder sensor installed on the electric traction motor (110) and the onboard control electronics vessel (124) of the traction motor (110) of the device (100).

[0049]

[0046] The inspection device (100) further comprises an external odometer (150) for measuring the distance traveled by the device (100) along the flexible duct (1) and a protective structure (151) for protecting the external odometer (150) against mechanical impacts.

[0050]

[0047] The inspection device (100) further comprises a marine-grade electronic circuit. The marine-grade electronic circuit comprises at least two watertight control electronics vessels, one main vessel installed on the ROV (300) and at least one secondary vessel (124) installed on the inspection device (100). A watertight vessel is an enclosure, generally cylindrical in shape, resistant to the external pressure of the water column at the operating depth, with a dry interior and atmospheric internal pressure.

[0051]

[0048] The main vessel connects the ROV (300) via electrical power and Ethernet cables for communication and data transfer to the surface computer and connects to at least one secondary vessel (124) for electrical power and communication and data transmission via electrical umbilical. This description is not intended to limit the scope of the matter disclosed herein, as other types of communication and data transmission means could be employed.

[0052]

[0049] The inspection device (100) may further comprise a visual monitoring system comprising at least one video camera, preferably at least two, and more preferably at least four video cameras. In addition, the visual monitoring system further comprises at least one spotlight, preferably at least two, and more preferably at least four spotlights, wherein at least one spotlight may be of any type employed in the area, and preferably an LED type spotlight.

[0053]

[0050] In one embodiment of the invention, the electric motors, video cameras and spotlights installed in the device (100) are interconnected to the secondary vessel on board (124) by submarine electric cables for power supply and data transmission.

[0054]

[0051] The internal electronics of the main vessel consist of (a) electronic equipment for powering, recording and displaying multichannel data from ultrasound sensors, which may be of any type used in the field, and preferably of the single crystal and phased array types, (b) embedded microcomputer for remote control and communication with the surface computer; (c) electronics for controlling the speed, voltage and current of electric motors; (d) signal acquisition electronics with digital and analog input channels, and digital and analog output channels; (e) network equipment management electronics of the Ethernet switch type, (f) constant voltage and variable current sources for powering electronic components and electric motors; (g) temperature, water presence and humidity sensors; (h) subsea electrical connectors for connection to components external to the electronic assembly.

[0055]

[0052] The microcomputer is connected to communication cables of any type that can be used in the area, but preferably of the USB 3.0 type, to the electronic power supply equipment for (i) recording the ultrasound sensor data in its memory and (ii) configuring the parameters and controlling the acquisition of ultrasound data by the device for inspection (100).

[0056]

[0053] The speed, voltage, and current control electronics are connected by electrical wires to the signal acquisition electronics for reading data from digital and analog signals, as well as digitally actuating analog switches that control the drive voltage of electric motors.

[0057]

[0054] Voltage sources and sensors are connected by electrical wires to the speed, voltage, and current control electronics to provide electrical voltage levels proportional to the internal temperature and humidity of the electronic components and pressure from the external environment for the purpose of measuring depth.

[0058]

[0055] The network equipment management electronics interconnect via cables, of any type that can be used in the area, but preferably of the Ethernet type, to the embedded microcomputer and to the electrical connectors for communication and data transmission to the surface computer.

[0059]

[0056] The electronic sensors of the visual monitoring system of the inspection device (100) may comprise at least one of, but not limited to, a temperature sensor, a depth sensor, a humidity sensor, an attitude sensor, a vibration sensor, an odometer and a water inlet sensor.

[0060]

[0057] Additionally, a method for inspecting flexible pipelines (1) is disclosed. The method comprises the initial steps of mechanically and electronically installing the inspection device (100) and the ROV (300) to a skid (200) and installing an operating computer on the control panel of the ROV (300).

[0061]

[0058] The skid (200) is a structure or platform used in the oil and gas industry, as well as in other industries, to mount and transport equipment efficiently and safely. Skids (200) are designed as modular units that can be easily transported and installed, facilitating the movement of heavy and complex equipment.

[0062]

[0059] In addition, the method also comprises the following steps: i- lowering an ROV (300) equipped with the inspection device (100) to the section of the flexible duct (1) to be inspected; ii- positioning the inspection device (100) adjacent to the flexible duct (1) using the robotic manipulator (310) of the ROV (300); iii- fixing the inspection device (100) to the flexible duct (1) using its fixing grips (140); iv- bringing the sensor module (131), comprising a plurality of sensors, close to the outer wall of the flexible duct (1); v- rotating the sensor module (131) 360 degrees along the perimeter of the cross-section of the flexible duct (1) in order to acquire data from the sensors; vi- moving the inspection device (100) along the flexible duct (1) using the traction and displacement system of the inspection device (100); vii- repeat steps ve vi, in order to acquire sufficient data for the inspection;viii- after completing data acquisition, open the fixing clamps (140) in order to detach the inspection device (100) from the flexible duct (1); ix- rest the inspection device (100) on the skid (200); and x- raise the ROV (300) to the surface.

[0063]

[0060] Furthermore, the method for inspecting flexible pipelines (1) also comprises, before using the inspection device (100), the definition of a digital twin through a preliminary analysis of the technical data of the flexible pipelines (1) to be inspected and analysis of the mechanical deformation of the flexible pipelines (1) in a submarine environment. The data from these analyses are used to feed a numerical simulation model for sonic propagation analysis, which calculates the behavior of ultrasonic signals through the internal layers of the flexible pipelines (1). In this way, the data intervals for extracting the ultrasonic signals and patterns by the inspection device (100) are defined. This simulation data is used in the elaboration of the correlation graphs of amplitude and sonic path, for the definition of classification criteria and standards, which will allow identifying whether the annulus is dry or flooded.

[0064]

[0061] After inspection of the flexible duct (1) by the inspection device (100), the data, preferably ultrasonic data, are collected and analyzed by an algorithm that extracts data in the intervals delimited by the digital twin, and classifies according to the classification criteria, of the relationship between time and amplitude. Subsequently, the algorithm generates graphs after data analysis, with point clouds and line patterns for each structure of the flexible duct (1), allowing conclusions to be drawn about the state of the flexible duct (1) in its general condition and along its diameter regarding the concentration of flooding.

[0065]

[0062] Still regarding the inspection method, the step of attaching the inspection device (100) to the flexible duct (1) is performed by means of the clamping jaws (140). After the inspection device (100) is positioned adjacent to the flexible duct (1) to be inspected, the hydraulic actuators of the clamping jaws (140) are activated, causing the clamping jaws (140) to close around the flexible duct (1), thus fixing the inspection device (100) to the flexible duct (1). Similarly, the step of detaching the inspection device (100) from the flexible duct (1) occurs by activating the hydraulic actuators of the clamping jaws (140), in order to open the clamping jaws (140).

[0066]

[0063] The step of rotating the sensor module (131) is performed by driving the electric motor (130), which transfers movement to the transmission box (132) coupled to the electric motor (130). The output shaft of the transmission box (132) transmits the rotational movement to a flexible rack, which is preferably a flexible toothed strip distributed along the arc of the sensor module (131), allowing the sensor module (131) to be rotated clockwise and counterclockwise.

[0067]

[0064] Additionally, after the step of moving the inspection device (100) along the flexible duct (1), the step of rotating the sensor module (131) 360° in order to acquire data from the sensors is repeated. Subsequently, the inspection device (100) can again be moved to another location on the flexible duct (1). The repetition of these two steps is terminated when sufficient data is collected, according to the information obtained by the digital twin or according to the decisions of the operator of the inspection device (100).

Claims

CLAIMS 1. Device for inspection (100) in flexible pipelines (1), said device operated by ROV (300), characterized in that it comprises: a marine-grade electronic assembly; a traction and displacement system; a sensor module (131) comprising a plurality of sensors for non-destructive inspection; wherein the sensor module (131) is connected to a radial displacement system; and at least one pan-tilt handle (120) capable of performing vertical and horizontal rotation of the device (100).

2. Device (100), according to claim 1, characterized in that it further comprises clamping claws (140), wherein each clamping claw (140) comprises at least one clamping arm (141), a rotating wheel (142) and a hydraulic actuator.

3. Device (100), according to claim 1, characterized in that the flexible ducts (1) can be ducts in injection lines or ducts in production lines.

4. Device (100), according to claim 1, characterized in that the marine-grade electronic assembly comprises at least two watertight control electronics vessels, at least one main vessel and at least one secondary vessel (124), wherein the at least one main vessel is installed in the ROV (300) and the at least one secondary vessel (124) is installed in the inspection device (100).

5. Device (100), according to claim 1, characterized in that the displacement traction system It comprises an electric traction motor (110), a traction track (111), a gearbox (112) and traction motor control electronics.

6. Device (100), according to claim 5, characterized in that it comprises a 4-function hydraulic hot-stab (122) that can be connected to and disconnected from the device (100) in emergency situations.

7. Device (100), according to claim 1, characterized in that the radial displacement system comprises at least one electric motor (130), a transmission box (132) and a handle for manual turning (126) or turning by the robotic manipulator (310) of the ROV (300).

8. Device (100), according to claim 1, characterized in that at least one pan-tilt handle (120) comprises at least two hydraulic actuators through which vertical and horizontal rotations are performed.

9. Device (100), according to claim 1, characterized in that it comprises at least one side lifting handle (121) and at least one rear handle.

10. Device (100), according to claim 1, characterized in that the flexible duct (1) to be inspected may comprise external diameters in the range of 200mm to 420mm.

11. Device (100), according to claim 1, characterized in that it further comprises a visual monitoring system, which comprises at least one video camera, preferably at least two, and more preferably at least four video cameras; and further comprises at least one spotlight, preferably at least two, and more preferably at least four spotlights.

12. Method for inspecting flexible ducts (1) using the inspection device (100) defined in any one of claims 1 to 11, characterized in that it comprises the following steps: i- lowering an ROV (300) equipped with the inspection device (100) to the section of the flexible duct (1) to be inspected; ii- positioning the inspection device (100) adjacent to the flexible duct (1) using the robotic manipulator (310) of the ROV (300); iii- fixing the inspection device (100) to the flexible duct (1) using its fixing grips (140); iv- bringing the sensor module (131), comprising a plurality of sensors, close to the outer wall of the flexible duct (1); v- rotating the sensor module (131) 360 degrees along the perimeter of the cross-section of the flexible duct (1) in order to acquire data from the sensors;vi- move the inspection device (100) along the flexible duct (1) using the inspection device's traction and displacement system (100); vii- repeat steps ve vi, in order to acquire sufficient data for the inspection; viii- after completing the data acquisition, open the fixing clamps (140) in order to detach the inspection device (100) from the flexible duct (1); ix- rest the inspection device (100) on the skid (200); and x- raise the ROV to the surface.

13. Method according to claim 12, characterized in that it comprises the definition of a digital twin, comprising the steps of: analyze technical data of the flexible ducts (1) to be inspected; feed a numerical simulation model of sonic propagation analysis with said data; define data ranges for extraction of ultrasonic signals and patterns by the inspection device (100) define classification criteria and standards to identify whether the annulus is dry or flooded.

14. Method, according to claim 12 or 13, characterized in that the data acquired by the inspection device (100) are collected and analyzed by an algorithm, which extracts the data in the intervals delimited by the digital twin; wherein the algorithm generates graphs that are compared with the graphs generated for the digital twin, allowing the conclusion of the state of the flexible duct (1).

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