Leak detection

Abstract

A method of determining a location of a leak in a pipeline is described, including processing captured image data associated with at least one image captured from within the pipeline to identify a temperature change in an internal surface of the pipeline in response to a temperature change of a fluid leaking from the pipeline, thereby determining a location of the leak in the pipeline. A system and apparatus for determining a location of a leak in a pipeline are also described.

Description

[0001] The present invention relates to detecting leaks in pipelines, in particular, but not exclusively, to a method and apparatus for non-destructive in-pipe detection of a fluid, such as a gas, leaking from a pipeline.

[0002] It is known that pipelines carrying fluids, such as gases, can leak from joints connecting sections of the pipeline together, from fittings located along the pipeline, and from cracks resulting from corrosion, pinholes or ruptures in the internal and / or external walls of the pipeline, and from third party damage. Conventional external leak detection methods rely on seeing a leak on the ground, hopefully at the location of the leak. Obstructive ground layers above the pipeline can cause the leaking gas to flow underneath, resulting in inaccurate locations of the leak, and unnecessary excavation and repair of otherwise structurally sound sections of the pipeline.

[0003] Known in-pipe leak detection systems include closed circuit television (CCTV) systems which can help visualise the pipeline and highlight joints, connections, fittings and leak indicators such as cracks, water ingress and poor joints. However, CCTV based systems are unable to confirm a leak and its exact location. Acoustic leak detection systems are also known, but these systems are often limited by "background" noise, traffic vibrations above the ground, internal pressure of the pipeline and local environment.

[0004] It is an object of certain embodiments of the present invention to provide a method and apparatus for detecting a leak of a fluid flowing along a pipeline and in particular to detect the exact location of the leak from the inside of the pipeline by utilising the fluid flowing through the pipeline.

[0005] It is an object of certain embodiments of the present invention to provide a method and apparatus for detecting a leak from the inside of a pipeline without having to shut down the flow of fluid being carried through the pipeline.

[0006] According to a first aspect of the present invention there is provided a method of determining a location of a leak in a pipeline, comprising:

[0007] processing captured image data associated with at least one image captured from within the pipeline to identify a temperature change in an internal surface of the pipeline in response to a temperature change of a fluid leaking from the pipeline to determine a location of a leak in the pipeline.

[0008] Optionally, the method comprises:

[0009] capturing at least one image at a first location along the pipeline; and

[0010] comparing the captured image data with reference image data associated with a corresponding reference image obtained at a location within the pipeline substantially corresponding to the first location.

[0011] Optionally, the method includes comparing at least one pixel of the captured image with at least one corresponding pixel of a reference image to identify temperature changes on the inner surface of the pipeline near the leak location.

[0012] Optionally, the method includes comparing pixel intensity / brightness and / or contrast distributions associated with corresponding pixels in the captured image and the reference image.

[0013] Optionally, the method includes classifying reference image data of multiple reference images obtained at different locations along the pipeline based on pixel intensity / brightness variations.

[0014] Optionally, the method includes creating a contrast threshold based on the pixel contrast distribution of multiple reference images obtained at different locations along the pipeline, and applying a contrast filter based on the contrast threshold to the captured image data of the corresponding captured image.

[0015] Optionally, the temperature of the inner surface of the pipeline near the leak location is lower than the temperature of the bulk fluid flowing along the pipeline and / or the temperature of the inner surface of the pipeline away from the leak location.

[0016] Optionally, the temperature of the inner surface of the pipeline near the leak location is higher than the temperature of the bulk fluid flowing along the pipeline and / or the temperature of the inner surface of the pipeline away from the leak location.

[0017] Optionally, the temperature of the leaking fluid increases at the leak location in response to an increase in the volume of the leaking fluid, thereby increasing the temperature of the inner surface of the pipeline near the leak location.

[0018] Optionally, the method includes actively heating a portion of the fluid flowing along the pipeline.

[0019] Optionally, the method includes actively heating a portion of the fluid flowing upstream or downstream of the leak location.

[0020] Optionally, the method includes determining the rate of temperature change of the inner surface of the pipeline near the leak location.

[0021] Optionally, the method includes determining the leakage velocity at the leak location based on the rate of temperature change and one or more of the following data: overall fluid temperature, overall fluid velocity, overall fluid pressure, surface temperature, surface hysteresis / phase response, surface temperature rise rate, surface temperature cooling rate, pipeline material thermal properties, leak location, and leak geometry / size.

[0022] Optionally, the method includes intermittently and actively heating a portion of the fluid flowing along the pipeline, and capturing the image data and one or more additional data during heating and cooling of the inner surface of the pipeline near the leak location.

[0023] Optionally, the method comprises blowing at least a portion of the actively heated fluid radially outwardly along or relative to a longitudinal axis of the pipeline.

[0024] Optionally, the method comprises heating the portion of fluid by at least one heating element of a device located in the pipeline.

[0025] Optionally, the method comprises controllably moving the device along the pipeline, wherein the device comprises the apparatus for capturing and obtaining the images.

[0026] Optionally, the apparatus comprises an infrared camera.

[0027] According to a second aspect of the application, there is provided a system for determining a location of a leak in a pipeline, comprising:

[0028] a device for positioning in the pipeline and comprising an apparatus for capturing images of an inner surface of the pipeline; and

[0029] a controller configured to process captured image data associated with at least one image captured from within the pipeline to identify a temperature change in the inner surface of the pipeline in response to a temperature change of fluid leaking from the pipeline to determine a location of a leak in the pipeline.

[0030] Optionally, the apparatus comprises an infrared camera.

[0031] Optionally, the device comprises a heater for heating a portion of fluid flowing along the pipeline.

[0032] Optionally, the device comprises a heater for heating a portion of fluid flowing upstream or downstream of the location of the leak.

[0033] Optionally, the device comprises a blower for blowing the portion of fluid radially outwardly along or relative to a longitudinal axis of the pipeline.

[0034] Optionally, the device comprises at least one sensor for sensing a bulk fluid temperature, a bulk fluid flow rate, a bulk fluid pressure, or an axial position of the device in the pipeline.

[0035] According to a third aspect of the application, there is provided a device for determining a location of a leak in a pipeline, comprising:

[0036] a body for controllably moving along an interior of the pipeline;

[0037] an image capture apparatus mounted to the body, the image capture apparatus for capturing images of an inner surface of the pipeline; and

[0038] a heater for actively heating a portion of fluid flowing along the pipeline.

[0039] Optionally, the device includes a blower for blowing a portion of the fluid radially outward along the pipeline or relative to the longitudinal axis of the pipeline.

[0040] Alternatively, the blower is configured to blow that portion of the fluid across the heating element of the heater.

[0041] Optionally, the body is supported on a plurality of surface-mount elements, each of which can be engaged with a pipeline.

[0042] Optionally, each of the plurality of surface-engaged elements may be selectively driven to move the device along the pipeline.

[0043] Optionally, the image capturing device can be selectively moved relative to the subject between a retracted position and an extended position.

[0044] Optionally, the device includes a controller configured to process captured image data associated with at least one image captured from within the pipeline to identify temperature changes on the inner surface of the pipeline in response to temperature changes in fluid leaking from the pipeline, thereby determining the location of the leak in the pipeline.

[0045] According to a fourth aspect of the invention, the use of the apparatus according to the third aspect of the invention for determining the location of a leak in a pipeline is provided. Attached Figure Description

[0046] Some embodiments of the invention will now be described with reference to the accompanying drawings, in which:

[0047] Figure 1a An apparatus according to certain embodiments of the present invention is shown, wherein the arm of the means supporting the image capture device is in an extended state;

[0048] Figure 1b It shows Figure 1a The device, wherein the arm of the device is in a retracted state;

[0049] Figure 2 The pipeline is shown Figure 1a and 1b A schematic diagram of the device;

[0050] Figure 3 Another embodiment of the device is shown;

[0051] Figure 4 Images captured by a device according to certain embodiments of the present invention are shown; and

[0052] Figure 5 A stitched image showing the interface between the leaking and non-leaking pipes is presented.

[0053] Detailed description

[0054] like Figure 1a and Figure 1b As shown, a device 100 according to certain embodiments of the invention includes a chassis 102 supported on a plurality of wheels 104, which are selectively driven in any direction by an electric motor coupled to the wheels via a gear assembly. Alternatively, the device may include a plurality of tracks, etc., and / or the device may be manually or automatically propelled along a conduit by a pushrod arrangement coupled to the device and terminating above ground. Suitably, all wheels are coupled to and selectively driven by the electric motor. The motor is coupled to an onboard controller 106, which is configured to communicate wirelessly or via a wired connection with an on-surface controller, which can be operated by an authorized user to selectively control the device from above ground. The on-surface controller is suitably a computing device including a user interface and a display, such as a tablet computer. An infrared (IR) camera module 108 is mounted to the end regions of a first pair of spaced-apart and parallel support arms 110. Each support arm 110 is pivotally coupled at its other end region to the corresponding end regions of a second pair of spaced-apart and parallel arms 112 and a third pair of spaced-apart and parallel arms 114. Each of the second pair of arms 112 and the third pair of arms 114 is pivotally coupled to a chassis 102 at its other end region. The first pair of arms 110 is connected to the second pair of arms 112 and the third pair of arms 114 such that the second and third pairs of arms rotate together, and each of the first pair of arms 110 remains parallel to the chassis 102. The second pair of arms 112 and / or the third pair of arms 114 is selectively rotated by a motor to raise or lower the first pair of arms 110 relative to the chassis, thereby raising or lowering the IR camera module 108. Figure 1a The camera module 108 is shown in its extended / raised position, while Figure 1b The camera module 108 is shown in a retracted / lowered position. Appropriately, the camera module 108 can be moved to any position between the retracted and extended positions. Furthermore, the camera module 108 can selectively rotate about a vertical and / or horizontal axis relative to the first pair of support arms 110, and / or the second pair of arms 112 and the third pair of arms 114 can selectively rotate about a vertical axis (e.g., by mounting to a turntable rotatable relative to the chassis). Such an arrangement can desirously allow the camera module to be selectively moved to a position and orientation that allows for optimal image capture of specific pipe features.

[0055] The heater and blower unit 116 is pivotally mounted between the second and third pairs of arms 112, 114 at about the middle along the second and third pairs of arms 112, 114 to move up or down relative to the chassis 102 along with the IR camera module 108 while remaining substantially horizontal and parallel to the chassis. The heater and blower unit 116 is coupled to the on-board controller 106 to allow selective turning on / off of the unit 116 when needed, as further described below.

[0056] The IR camera module 108 includes an IR illumination device 118, such as an IR LED array, and a camera 120 for capturing still and / or motion images (video) of the pipe wall and its features / fittings. The camera module 108 is coupled to the on-board controller 106 for locally storing the image data and / or sending the image data to the surface controller for storage and / or processing.

[0057] As Figure 2 As schematically illustrated in FIG. 2, an apparatus 200 according to an alternative embodiment of the present application is positioned within a pipe 250 and is driven along the pipe in the direction of gas flow through the pipe (arrow G). The apparatus 200 includes a main body 202 supported on wheels or tracks 204, an IR camera module 208 mounted on a front end region of the main body, and a blower 215 and a heater 217 mounted on a rear end region of the main body. The blower 215 blows some of the gas flowing through the pipe past the heating elements of the heater 217 to cause the temperature of the gas to increase. Alternatively, an acoustic device can be provided to locally excite the gas by vibration and in turn cause the temperature of the gas to increase. The heated gas T is either mixed with the remaining line gas or is accelerated radially outward by the blower toward the pipe wall. Alternatively, the blower can not be needed and the heated gas passing through the heater can be drawn outward to the leak given the pressure differential across the leak point (e.g., joint or crack) 252. The heated gas acts as a "tracer" or "smoke stream" that can be detected and compared to the temperature of the remaining cooler gas flowing through the pipe and / or the pipe surface, as further described below. The leaked heated gas transfers heat to the pipe or feature, and this relative warming is detected by the on-board thermal imaging camera. Additional sensor data, such as gas temperature, flow rate, pipe material, etc., are optionally captured and used to correlate the observed temperature changes of the pipe wall or feature to the leak flow rate.

[0058] Figure 3An apparatus 300 according to an alternative embodiment of the application is shown. The apparatus 300 includes a main body 302 mounted on a pair of drive tracks or wheels 304. The main body 302 is substantially rectangular and hollow box-shaped section with an open front end region 303. An IR camera module 308 is located in the open front end region and is selectively rotatable about at least a horizontal axis. The rear end region of the main body is open or can include a grating or slots. A blower and heater (not shown) are located in the rear end region of the main body and are configured to blow air backwards against the airflow in the pipe, causing turbulence and mixing of the heated and unheated airflows. Alternatively, the heater element can be located "upstream" of the blower in the main body, such that the gas is blown over the heater element. The excited gas flow is thereby heated so that it can be used as a "tracer" or "plume" that can be detected and compared to the temperature of the remaining cooler gas flowing through the pipe and / or the surface of the pipe, as described further below. The thermal camera optics can be selected to either directly view the heated gas flow or only be able to see the heated surface of a leaking pipe at which the heated / mixed gas is in contact. This is achieved by tuning / adjusting the thermal camera filter to only see certain wavelengths of IR radiation based on the emission spectrum of the pipeline gas. This causes the gas to appear semi-transparent or transparent in the image relative to the unheated / heated gas.

[0059] In use, the reference images of the interior of the pipeline are initially captured by the IR camera module when the apparatus is travelling along the interior of the pipe and the heater or blower is not operating. The reference image data is stored in memory for processing. Position information is optionally assigned to the data of each reference image. The apparatus is travelled along the same length of the pipe and images are captured at the same or similar positions along the pipe, but this time the heater and blower are operating to heat the gas. A surface controller, such as a computer configured to execute a computer program, receives the raw image data corresponding to each captured image of the pipe wall or fitting etc. and compares the captured image data to the corresponding reference image data corresponding to substantially the same position along the pipe. The computer program executable on the computer is configured to compare the captured unheated images to the closest corresponding heated image, for example, each captured image is effectively "superimposed" together with the reference image. The analysis looks for overall changes in the characteristic temperature to determine if a leak has occurred in the pipe at the position corresponding to the particular image.

[0060] To filter out unwanted "noise" from the images, the feature contrast is calculated, and a filter can be applied to the images to select only variations within a contrast threshold that can be characteristic of a leak on the pipe wall, for example, a particle on the inner surface will also heat up and will be observed. These features are removed with a contrast filter, as the edges of these features have a higher contrast than the temperature gradient presented by a typical leak, due to the lower contrast presented by the heat transfer from the leak to the pipe wall.

[0061] The device suitably comprises a position tracking device, such as a global positioning system (GPS), a magnetic flux system or an acoustic measurement instrument using two-way time of flight to calculate distance travelled and flow conditions within the pipe, for determining the position of the device along the pipe and associating each reference image and each captured image with position coordinates or the like.

[0062] As an example, as shown in Figure 4 Without power to the heater elements (i.e. without heating the gas flowing through the pipe), images of the cross-section of the gas pipe are captured by the device at known positions along the pipe (labelled A). Raw image data is captured at every X units of distance travelled along the pipe and a series of baseline / reference images are formed, labelled B. The reference images are computed to classify the level of temperature variation across the pipe cross-section under baseline conditions. ROIs (regions of interest) can be selected on the images and the computer computes the baseline image luminance and contrast distribution of the image or selected ROIs. These measurements form the baseline values for the pipe cross-section.

[0063] Then, when the device is moved again along the inside of the pipe, images of the pipe wall are captured, but this time the heaters are powered, creating a heated gas flow within the pipe. The controller receives the captured image data directly from the camera module or from memory used to store the captured images and processes the captured image data to compare the captured image data at a particular position along the pipe with the closest reference image data corresponding to that position. The luminance (temperature) and contrast distribution of the heated image or image ROIs are computed. The captured images are processed in the same way as the unheated images. Contrast filtering can be used to remove noise from internal debris and particles and focus the results on features with expected spatial temperature gradients (contrast) proportional to the heat transfer properties of the pipe material. The baseline and heated results are then compared and the difference used to infer the presence of a leak at that position / ROI.

[0064] Result interpolation can be used when there is not a perfect match between the location of the "baseline" (reference) image data and the "heat" (captured) image data. In cases where there can be "sensor drift" in the location record, the controller (e.g. computer) can cross correlate the CCTV images taken with the thermal images to select the baseline image and heat image that are closest to being aligned for that particular location.

[0065] Gradient or contrast filtering algorithms are applied to distinguish between internal surface contamination and features being heated by the gas. These features typically have a higher temperature gradient because they are less conductive and are discontinuous with the pipe body. Since heat can flow, there is a low contrast edge to the leak, with increased gradient through the pipe wall. The gradient rate is measured to infer information about the pipe material and condition and the leak rate.

[0066] Particle and threshold filtering is used to improve clarity and isolate potential leaks. Detected and classified leak images are stored to train a processor, i.e. a computer program executable on a computing device, to automatically detect leaks. The thermal images used to train the processor contain other data, including acoustic, temperature, pressure, and flow data.

[0067] For more detailed analysis, the device is held stationary at the location of interest. A baseline unheated image is captured. The heater is then activated, and IR cameras and sensors used to determine gas temperature, flow rate, pipe material, etc. capture data throughout the static heating and cooling cycle. Detailed analysis is then able to calculate the rate of change of contrast and temperature at the location or feature ROI. This additional information to the absolute information forms information that can more accurately indicate the leak rate. This more detailed image processing according to certain embodiments of the present application includes the following steps to additionally determine the scale of the leak:

[0068] Determining the pipe overall flow rate and temperature at the location of the leak;

[0069] Determining the thermal conductivity of the pipe / feature material;

[0070] Determining the defect (leak) geometry;

[0071] Determining the gas pressure; and

[0072] Determining the rate of change of feature temperature and contrast.

[0073] The overall flow rate can be measured directly by the device or determined from the rate of change of overall flow temperature measured by temperature sensors provided on the device. The overall temperature at the location of the leak can be measured directly by temperature sensors or can be calculated from the heater output temperature, the overall flow rate of the gas, the pipe line size, and the distance from the heater using energy conservation gas temperature related equations.

[0074] The thermal properties of the pipe and feature materials are known and tabulated for common materials. The leak geometry is determined by image analysis. The captured (heated) images are analyzed. The pre-“heated” images, which include the heated gas, create features that more closely show the defect geometry before the heating area around the defect-encircling material’s thermal conductivity shows features. Additionally, the later “heated” images show a larger heated area that can be processed to create a distance map from the “edge” back to a common center point set representing the defect geometry. With known pipe dimensions and camera positioning (or by laser point / 3D scanning), the defect size and shape can be accurately determined.

[0075] The gas pressure is measured by a pressure sensor. The rate of change of feature temperature and contrast is calculated between images, such as frames of a video of the heating process taken with a thermal camera.

[0076] A curve of the rate of change of temperature of the pixels within the image and feature / ROI is measured. The absolute temperature, temperature lag / phase response, growth rate, cooling rate, and any frequency changes of the pixels / features are measured and saved. The curve is fit to the results of the measurements taken to yield additional rate change parameters. Filters are applied in a similar manner to remove high and low contrast elements that are not relevant to the expected material.

[0077] The calculated values are run through energy conservation and transfer equations to calculate the proportional leak rate through the feature that would cause the observed temperature rise under the measured conditions. This is then saved to a dataset.

[0078] Multiple visits to this location can be made to build a dataset showing the change in leak over time.

[0079] For example, when some of the leaking gas expands through a crack or loose fitting, the pressure decreases. In turn, its temperature will typically also decrease through the Joule Thompson effect. However, the relatively warm heated gas increases the surface temperature of the local pipe or fitting where the leak is occurring, creating a temperature gradient / difference between the heated gas and the cooler gas body and / or the local pipe surface where the leak is occurring versus the pipe body where no leak is occurring. Whether the leaking gas causes passive heating (hydrogen) or cooling (natural gas), the scale of the active heating of the pipe or fitting near the leak location is typically greater than the scale of the cooling or heating through this Joule Thompson effect. The temperature gradient of the pipe or fitting caused by the gas heating near the leak location can be detected by the IR camera module and can be compared to reference image data to accurately determine the occurrence and location of the leak without considering the Joule Thompson effect in isolation.

[0080] The device can also determine whether a connection to the pipe is consuming gas.Figure 4 The image labeled 1 shows a captured image in which neither leakage nor consumption through the service connection / tap is present. Figure 4 The image labeled 2 shows a captured image in which both leakage and consumption are present. The relatively bright central region 402 indicates gas flow through the pipe (consumption / supply), and the relatively bright localized region 404 at the bottom of the image indicates leakage through the joint, as the excited and heated gas flow escapes through the leaking joint and warms the localized surface of the leak relative to the cooler surface of the pipe away from the leak. Figure 4 The image labeled 3 shows a captured image in which consumption is present but no leakage is present. Figure 4 The image labeled 4 shows a captured image in which leakage is present but no consumption is present, as indicated by the relatively bright localized region 406 near the bottom of the image.

[0081] Figure 5 shows two halves of a captured image spliced together that are different. As shown on the right side of the image, the peripheral interface 548 between the pipe wall 550 and the fitting 552 is relatively well defined by the dark line, indicating that no leakage is occurring at the joint. However, as shown on the left side of the image, the upper left portion of the joint region includes multiple relatively bright localized regions 554 and is less well defined, indicating that leakage is occurring on the joint. The relatively bright central region 556 in each image indicates that gas is flowing through the service pipe (consumption) in view of some of the heated / excited gas flow mixing with the main gas flow and being detected by the IR camera.

[0082] The base reference image data can be selected from a database of stored reference data based on the known or particular type of pipeline. This process can be automated by configuring the controller to automatically process each captured image with the selected or predetermined base reference image data. The controller can be configured to provide a visual and / or audible indication when a leak is detected.

[0083] An alternative embodiment of the present invention involves detecting the location of a leak from inside the pipeline by comparing the temperature of the pipe surface or fitting near the leak to the temperature of the pipe surface away from the leak. When gas passes through a crack or leaking joint, its volume increases, and its temperature typically decreases, but can also increase (e.g., for hydrogen). This typical temperature decrease has a cooling effect on the pipe surface near the leak, and a temperature difference between the near and far surfaces of the leak relative to the leak can be detected, which can be used to precisely determine the occurrence and location of the leak. This method does not require heating at least some of the gas flowing through the pipe, and when compared to “active” leak detection methods that involve heating and exciting the gas near the location of the leak, this method can be referred to as a “passive” leak detection method.

[0084] The method of detecting leaks according to certain embodiments of the present application can be performed by a device as shown and described herein, or by a differently configured device that meets the requirements but is suitably configured, such as a downhole tool or pigging apparatus, which can not include, for example, a plurality of wheels, and can be pushed along a pipeline by a push rod or the like, or lowered downhole on a cable or the like under the influence of gravity. The terms "pipeline" and "pipe" are to be understood as including a single length of pipe or conduit consisting of a plurality of pipe sections connected together to form an underground or above ground pipeline or downhole wellbore, etc., including any fittings or service lines extending from the main pipeline. The pipeline can form a pipe in a building or underground tunnel, etc., for a fluid carrying or waste water system. The pipeline can have any suitable cross section, such as circular, square, etc.

[0085] The captured data can be referenced and subsequently processed by machine learning and artificial intelligence algorithms to identify possible leak conditions. These conditions can then be searched and prioritized for replacement of repair activities. The captured information can be used as evidence of whether the pipeline is suitable for carrying fluids therein. The detection can be used for various pipes, including gas, drainage, process, nuclear, and sewer. Baselining data can include other measurements used with leak detection. These can include acoustic measurements, heat, pressure, and radiation to detect increases in radon levels accumulated at leak joints. Baselines can be captured at time intervals to determine changes in the pipeline or feature over time.

[0086] Accordingly, certain embodiments of the present application provide a method and apparatus for efficiently determining the location of a leak of a fluid, such as a gas, in a pipeline, and accurately identifying the location of the leak from within the pipe itself. According to certain embodiments of the present application, a fluid (gas or liquid) in a pipeline can be used to determine the location of a leak if the fluid has a transmission region in the IR range. The method is non-destructive and eliminates the need for destructive and inaccurate drilling or other forms of large scale excavation. Once the location and nature of the leak is accurately determined, a single excavation can be performed, if necessary, to repair the leak from outside the pipe. Alternatively, a repair device can be sent along the pipeline to repair the leak from within the pipe, thereby completely eliminating the need for excavation. The method and apparatus according to certain embodiments of the present application are particularly compatible with future hydrogen networks, and do not rely on detecting a pressure drop across the wall of the pipeline.

Claims

1. A method of determining a location of a leak in a pipeline, comprising: processing captured image data associated with at least one image captured within the pipeline to identify a temperature change in an inner surface of the pipeline in response to a temperature change of a fluid leaking from the pipeline, thereby determining a location of a leak in the pipeline, wherein the processing comprises: capturing the at least one image at a first location along the pipeline; and comparing the captured image data to reference image data associated with a corresponding reference image obtained at a location within the pipeline corresponding to the first location, wherein the method comprises actively heating a portion of the fluid flowing along the pipeline.

2. The method of claim 1, comprising comparing at least one pixel of the captured image to at least one corresponding pixel of the reference image to identify a temperature change in the inner surface of the pipeline proximate to the location of the leak.

3. The method of claim 2, comprising comparing pixel intensity / brightness and / or contrast distributions associated with the corresponding pixels of the captured image and the reference image.

4. The method of claim 3, comprising classifying reference image data of a plurality of reference images obtained at different locations along the pipeline based on pixel intensity / brightness changes.

5. The method of claim 3 or 4, comprising creating a contrast threshold based on pixel contrast distributions of a plurality of reference images obtained at different locations along the pipeline, and applying a contrast filter based on the contrast threshold to captured image data of a corresponding captured image.

6. The method of any preceding claim, wherein, the temperature of the inner surface of the pipeline proximate to the location of the leak is lower than a temperature of a body of fluid flowing along the pipeline and / or a temperature of an inner surface of the pipeline distal to the location of the leak.

7. The method of any one of claims 1 to 5, wherein, the temperature of the inner surface of the pipeline proximate to the location of the leak is higher than a temperature of a body of fluid flowing along the pipeline and / or a temperature of an inner surface of the pipeline distal to the location of the leak.

8. The method of claim 7, wherein, in response to an increase in a volume of the leaking fluid, the temperature of the leaking fluid increases at the location of the leak, thereby increasing the temperature of the inner surface of the pipeline proximate to the location of the leak.

9. The method of claim 1, comprising determining a rate of temperature change of the inner surface of the pipeline proximate to the location of the leak.

10. The method of claim 9, comprising determining a leak flow rate at the location of the leak based on the rate of temperature change and one or more of the following data: bulk fluid temperature, bulk fluid flow rate, bulk fluid pressure, surface temperature, surface hysteresis / phase response, surface temperature rise rate, surface temperature cool down rate, pipeline material thermal properties, leak location, and leak geometry / dimensions.

11. The method of claim 10, comprising intermittently actively heating a portion of the fluid flowing along the pipeline, and capturing the image data and one or more additional data during heating and cooling of the inner surface of the pipeline proximate to the location of the leak.

12. The method of claim 1, comprising blowing at least a portion of the actively heated fluid radially outwardly along or relative to a longitudinal axis of the pipeline.

13. The method of claim 1, comprising heating the portion of fluid by at least one heating element of a device positioned in the pipeline.

14. The method of any preceding claim, comprising controllably moving a device along the pipeline, wherein the device comprises an apparatus for capturing and obtaining the images.

15. The method of claim 14, wherein, The apparatus comprises an infrared camera.

16. A system for determining a location of a leak in a pipeline, comprising: a device for positioning in a pipeline, comprising an apparatus for capturing images of an inner surface of the pipeline; a heater for actively heating a portion of fluid flowing along the pipeline; and a controller configured to process captured image data associated with at least one image captured from within the pipeline to identify a temperature change in the inner surface of the pipeline in response to a temperature change of fluid leaking from the pipeline to determine a location of a leak in the pipeline, wherein the processing comprises: capturing the at least one image at a first location along the pipeline; and comparing the captured image data to reference image data associated with a corresponding reference image obtained at a location within the pipeline corresponding to the first location. The apparatus comprises an infrared camera.

17. The system of claim 16, wherein, The device comprises a blower for blowing the portion of fluid radially outwardly along or relative to a longitudinal axis of the pipeline.

18. The system of claim 16, wherein, The device comprises at least one sensor for sensing a bulk fluid temperature, a bulk fluid flow rate, a bulk fluid pressure, or an axial position of the device in the pipeline.

19. The system of any one of claims 16 to 18, wherein, 20. A device for determining a location of a leak in a pipeline, comprising: a body for controllably moving along an interior of a pipeline; an image capture apparatus mounted to the body for capturing images of an inner surface of the pipeline; and a heater for actively heating a portion of fluid flowing along the pipeline.

21. The device of claim 20, comprising a blower for blowing a portion of fluid radially outwardly along or relative to a longitudinal axis of the pipeline. The blower is configured to blow the portion of fluid over a heating element of the heater.

22. The apparatus of claim 21, wherein, The body is supported on a plurality of surface engagement elements, each surface engagement element being engageable with the pipeline.

23. The apparatus of any one of claims 20-22, wherein, Each of the plurality of surface engagement elements is selectively drivable to move the device along the pipeline.

24. The apparatus of claim 23, wherein, The image capture apparatus is selectively movable relative to the body between a retracted position and a deployed position.

25. The apparatus of any one of claims 20-24, wherein, 26. The device of any one of claims 20 to 25, comprising a controller configured to process captured image data associated with at least one image captured from within the pipeline to identify a temperature change in the inner surface of the pipeline in response to a temperature change of fluid leaking from the pipeline to determine a location of a leak in the pipeline. ​ 27. Use of the apparatus according to any one of claims 20 to 26 for determining a location of a leak in a pipeline.

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