WO2015199549A1

WO2015199549A1 - Method for hydraulic deployment of pipeline communication and monitoring system

Info

Publication number: WO2015199549A1
Application number: PCT/NO2015/050114
Authority: WO
Inventors: Tor Mathias DYBVIK
Original assignee: Dybvik Tor Mathias
Priority date: 2014-06-24
Filing date: 2015-06-23
Publication date: 2015-12-30

Abstract

The invention relates to a system (10) for monitoring a pipeline (100) for transporting a commodity. The system (10) comprises a tubular structure (14) for being provided in, on or near the pipeline (100) extending over a predefined length of the pipeline (100). The tubular structure (14) comprises a transport fluid (16) and a monitoring string (12) extending through the tubular structure (14). The monitoring string (12) is designed with a plurality of buoyancy elements (12b) for creating a net buoyancy of the monitoring string (12) that is substantially neutral with respect to the transport fluid (16). The invention further relates to a method of deploying such system (10). One of the key features of the invention is that the monitoring line is dragged into the tubular structure by means of drag forces applied by a moving transport fluid.

Description

METHOD FOR HYDRAULIC DEPLOYMENT OF PIPELINE COMMUNICATION AND MONITORING SYSTEM

The invention relates to a system for monitoring a pipeline for transporting a commodity. The invention also relates to a method of deploying such system.

Pipeline transport is the transportation of goods or material through a pipe. The best data, in 2014, gives a total of slightly less than 3.5 million km of pipeline in 120 countries of the world. Pipeline and Gas Journal's worldwide survey figures indicate that 118,623 miles (190,905 km) of pipelines are planned and under construction. Of these, 88,976 miles (143,193 km) represent projects in the planning and design phase; 29,647 miles (47,712 km) reflect pipelines in various stages of construction. Liquids and gases are transported in pipelines and any chemically stable substance can be sent through a pipeline. Pipelines exist for the transport of crude and refined petroleum, fuels - such as oil, natural gas and biofuels - and other fluids including sewage, slurry, water, and beer. Pipelines are useful for transporting water for drinking or irrigation over long distances when it needs to move over hills, or where canals or channels are poor choices due to considerations of evaporation, pollution, or environmental impact. Pneumatic tubes using compressed air can be used to transport solid capsules.

Oil pipelines are made from steel or plastic tubes, which are usually buried, either under the ground or under the sea/ocean. The oil is moved through the pipelines by pump stations along the pipeline. Natural gas (and similar gaseous fuels) are lightly pressurised into liquids known as Natural Gas Liquids (NGLs). Natural gas pipelines are constructed of carbon steel or composites.

Conditions that adversely affect the delivery of the commodity being transported include internal obstructions, leaks and external damages. External damage can be detected as vibrations when they occur, and leaks can be sensed as temperature changes, vibration caused by turbulence, or changes in pressure.

For oil and gas pipelines, a concern is the formation of hydrates, wax or asphalts inside the pipeline. Monitoring temperature along the pipeline can help detect the conditions un- der which such formation occurs. Furthermore, sensing vibration or pressure differentials can help detect the formations when they have occurred. In order to detect the location of an anomaly the sensors must be evenly distributed along the full length of the pipeline.

The current state of the art in pipeline monitoring includes interferometric optical sensing where an optical fibre is employed as a sensor. Temperature variations, mechanical vibration or deformation introduce micro-bends or stresses in the optical fibre, which can be detected as reflections or a changes in optic transmission. By analysing the reflection or transmission changes carefully, it is possible to identify the nature of the disturbance and its approximate location. Optical sensing has the advantage that the sensor is passive and uniform, and can be embedded into the pipeline, but it is typically limited in range to approximately 40-50km. For longer distances an active electronic device must be placed between each optical sensing segment, this device requires power and a separate communication bus, which might be another optical fibre.

Newer generations of composite oil and gas pipelines can accomplish much longer distances between pumping stations than traditional steel pipelines, up to several hundreds of kilometres. This places greater demand on the monitoring technology, and further compounds the problem with long sensor runs.

In view of the recent developments there is a need for an efficient method to deploy a monitoring technology which allows for monitoring over much larger distances, for instance in excess of 100km.

The invention has for its object to remedy or to reduce at least one of the drawbacks of the prior art, or to at least provide a useful alternative to prior art.

The object is achieved through features, which are specified in the description below and in the claims that follow.

The invention is defined by the independent patent claims. The dependent claims define advantageous embodiments of the invention.

In a first aspect the invention relates to a system for monitoring a pipeline for transporting a commodity. The system comprises a tubular structure for being provided in, on or near the pipeline extending over a predefined length of the pipeline. The tubular structure comprises a transport fluid and a monitoring string extending through the tubular structure. The monitoring string is designed with a plurality of buoyancy elements for creating a net buoyancy of the monitoring string that is substantially neutral with respect to the transport fluid.

The effects of the system for monitoring in accordance with the invention are as follows. In the first place the deployment of the system is rendered very easy by providing a tubular structure in, on near the pipeline to be monitored (such tubular structure may even be integrated into the pipeline). Subsequently, the transport fluid may be inserted into the tubular structure and subsequently the monitoring string may be conveniently inserted into the tubular structure, i.e. the tubular structure automatically guides the monitoring string. Because of the net neutral buoyancy (provided by the buoyancy elements) of the monitoring string the insertion of the monitoring string is greatly facilitated. Moreover, the net neutral buoyance enables that the transport fluid can drag the monitoring string over very long distances, easily over 100km. Up to today, solutions like this have not been seen in the field.

In order to better understand the invention a few terms are further defined hereinafter.

Where this description refers to "neutral buoyancy", "a net neutral buoyancy", "neutral buoyant", "substantially neutral", or the like, it is meant that the net or effective mass density of the whole monitoring string is designed to be equal to or almost equal to the mass density of the transport fluid. This may imply that some parts of the monitoring string have a larger mass density than the transport fluid and other parts have a lower mass density than the transport fluid. For the invention to work it is not essential that there is absolute neutral buoyancy as long as the buoyancy is close to neutral. Experiments and calculations have shown that the mass density of the fluid and the average mass density of the monitoring does preferably not deviate more than 3% from each other either way in order to minimize friction through the passage through the tubular structure..

It is to be noted that the buoyancy elements in the monitoring line may be designed to exhibit an inverse correlation between density and temperature so as to match the coefficient of expansion of the transport fluid and retain neutral buoyancy throughout the full temperature range of deployment. This is an advantageous embodiment of the monitoring system of the invention.

Where this description refers to "commodity" this term is supposed to include virtually any product, which may be transported through a pipeline, even if the idea of the invention was born in the petroleum industry, and more particularly in subsea pipelines thereof. The invention is applicable basically any technical field where commodities are transported over long pipelines, in particular where such pipelines are not easily accessible. Where this description refers to "first end" and "other end" these terms are referring to the tubular structure comprising monitoring string, and not the pipeline. The pipeline may extend further. The first end and the other end rather define a section of the pipeline, which is to be monitored to the monitoring system of the invention.

An embodiment of the system in accordance with the invention further comprises, when being deployed, a reservoir at the first end of the tubular structure for holding the transport fluid and for providing the transport fluid to the tubular structure. This embodiment constitutes a convenient feasible solution for providing (feeding) the transport fluid to the tubular structure. The reservoir may be pressurized or at atmospheric pressure. In case of a pressurized reservoir a valve may be provided to be able to regulate the provision of the transport fluid to the tubular structure.

An embodiment of the system in accordance with the invention further comprises a pump coupled between the reservoir and the tubular structure, wherein the pump is configured for pushing the transport fluid into the tubular structure. This embodiment is particularly advantageous in case the pressure in the reservoir is low or at atmospheric pressure.

An embodiment of the system in accordance with the invention further comprises a drainage system coupled to the other end of the tubular structure for receiving the transport fluid therefrom. The advantage of this embodiment is that there is no need for a return line of the transport fluid, rendering the system cheaper.

An embodiment of the system in accordance with the invention further comprises a further tubular structure coupled to the other end of the tubular structure and running parallel with the tubular structure back to the first end for returning the transport fluid back to the first end for being drained there. The advantage of this embodiment is that there is no need to be present at the other end of the drainage system, when the monitoring system is being deployed. The only thing that needs to be monitored is the length over which the monitoring line has gone into the tubular structure.

In an embodiment of the system in accordance with the invention the monitoring string comprises a supply and communication line with a plurality of sensors distributed over its length and being electrically connected with said supply and communication line. This configuration is particularly advantageous, because it facilitates the provision of as many sensors as desired, having any relative distance between the sensors as desired. It is also possible to implement sensors of different kinds over the length of the supply line. In an embodiment of the system in accordance with the invention said sensors are configured for sensing at least one of a group of properties of the commodity within the pipeline comprising: temperature, pressure, and vibration. These properties are the most important in monitoring potential problems in the pipeline.

In an embodiment of the system in accordance with the invention said sensors are at least partially provided in between the buoyancy elements. This embodiment forms a first variant of implementing the sensors in the monitoring line. An advantage of this embodiment is that the buoyancy members may act as a form of protection for the sensors.

In an embodiment of the system in accordance with the invention said sensors are at least partially provided within the buoyancy elements. This embodiment forms a second variant of implementing the sensors in the monitoring line. An advantage of this embodiment is that it may be easier to manufacture the monitoring line, keeping the buoyancy function separate from the sensor function.

An embodiment of the system in accordance with the invention further comprises, when in operational use, a monitoring station coupled with the monitoring string for carrying out the monitoring of the pipeline. Once, the system has been deployed, the monitoring line may be coupled to the monitoring string for allowing monitoring of the pipeline, for instance by reading out the respective sensors in embodiments of the system.

In an embodiment of the system in accordance with the invention the system further comprises, when being deployed, a feeder wheel at the first end of the tubular structure for feeding the monitoring string into the tubular structure when it is pushed therein by the transport fluid. The feeder wheel, also being referred to as a reel system, forms a convenient way of inserting the monitoring string into the tubular structure.

In a second aspect the invention relates to a method of deploying a system in accordance with the invention. The method comprises steps of:

inserting the monitoring string in the first end of the tubular structure;

supplying the transport fluid into the first end, while the transport fluid drags the monitoring string further into the tubular structure, and

continuing supplying the transport fluid until the other end of the tubular structure has been reached.

The method of the invention has been proven to be a convenient way of deploying a monitoring string, i.e. using a transport fluid in a dedicated tubular structure for pushing the monitoring string along a certain predefined length of the pipeline.

An embodiment of the method in accordance with the invention further comprises the step of draining the transport fluid at the other end of the tubular structure simultaneously with the supplying of the transport fluid at the first end. The advantages and effects of this embodiment of the method follow that of the corresponding embodiment of the system.

An embodiment of the method in accordance with the invention further comprises the step of facilitating the inserting of the monitoring string with a feeder wheel at the first end of the tubular structure, wherein the speed of the feeder wheel is matched to the flow speed of the transport fluid. The advantages and effects of this embodiment of the method follows that of the corresponding embodiment of the system.

An embodiment of the method in accordance with the invention further comprises, before the step of inserting the monitoring string, the step of providing the tubular structure in or on a pipeline for transporting a commodity. The advantages and effects of this embodiment of the method follows that of the corresponding embodiment of the system.

In the following is described examples of preferred embodiments illustrated in the accompanying drawings, wherein:

Fig. 1 shows a first embodiment of the system in accordance with the invention including aspects of its deployment;

Fig. 2 shows a second embodiment of the system in accordance with the invention including aspects of its deployment, and

Fig. 3 shows the second embodiment of the system when in operational use.

The invention is about a system for monitoring a pipeline and about a method of deploying such system.

Fig. 1 shows a first embodiment of the system 10 in accordance with the invention including aspects of its deployment. This embodiment concerns a system 10 comprising an elongated object to be monitored, such as a transport pipe 100, with an adjacent or integrated pipe, tube or channel 14 (referred to as "tubular structure" in the claims). The tube 14 is filled with a fluid 16 (referred to as "transport fluid" in the claims). A string including communication capability and monitoring capability 12 is designed to be neutral buoyant or close to neutral buoyant when immersed in the fluid 16. The string 12 is then deployed into the tube 14 through hydraulic pumping of the fluid 16 through the tube 14. The string 12 is designed to provide a longitudinally uniform drag coefficient to ensure that the fluid 16 exerts an evenly distributed motive force along the length of the string 12. The elongated object 100 to be monitored may be an oil or gas pipeline. The fluid 16 may comprise transformer oil. The string 12 may be inserted into the tube 14 through the means of a rotating wheel 18 (referred to as "feed wheel" in the claims) that prevents backflow of the fluid 16 while allowing deployment of the string 12 at a speed matched to the flow of the fluid 16. Thus, effectively this embodiment relates to a device 10 for moving a string of items 12 that has at least communication capability or monitoring capability along a monitoring tube or channel 14, wherein the propulsive force is drag force from a flowing fluid 16.

Fig. 2 shows a second embodiment of the system in accordance with the invention including aspects of its deployment. The figure will be mainly discussed in as far as it differs from or gives further information than Fig. 1 . In order to facilitate the deployment of the monitoring string 12 into the tubular structure 14 a transport fluid feeding system 30 is provided at a first end 14-1 of the tubular structure 14, and a transport fluid drainage system 40 is provided at a second end 14-2 of the tubular structure 14. The fluid feeding system 30 comprises a reservoir 32 for holding the transport fluid 16. The reservoir 32 is connected to a (hydraulic) pump 34 via a first connecting tube 33. A second connecting tube 35 connects the pump 34 to the tubular structure 14 close to the first end 14-1 . The transport fluid drainage system 40 comprises a further connecting tube 41 , which connects the other end 14-2 of the tubular structure 14 to a further reservoir 42 being part of the drainage system 40.

Fig. 2 further illustrates some more details on the monitoring string 12. The monitoring string 12 comprises a supply and communication line 12sc extending over its full length. At various locations along the supply and communication line 12sc there is provided sensors (not shown). The supply line may be a high-voltage supply line (these are typically voltages of 1500V DC or more). The supply and communication line 12sc may comprise a communication bus, for example. Each sensor is configured for sensing properties such as temperature, pressure or vibrations. In an alternative embodiment this line 12sc is only configured for supplying electric energy to the sensors, whereas the sensors communicate wirelessly. At regular intervals there is provided buoyancy elements 12b for creating the earlier-mentioned neutral buoyancy of the monitoring string 12 with respect to the transport fluid 16. During deployment of the monitoring string 12 the transport fluid 16 is pumped from the reservoir 32 into the tubular structure 14 at the first end 14-1 resulting in a flow speed and flow direction of the transport fluid as illustrated by the arrows 16fd. While flowing the transport fluid 16 creates a drag force (or tractive force) on the monitoring string 12 moving it to the end. The feed wheel 18 may be used to facilitate feeding the monitoring string 12 at a speed that is matched with the flow speed. In order for the system to work it is required to either drain the transport fluid 16 at the other end 14-2 of the tubular structure or to provide a return line for the transport fluid. In this embodiment there is provided a drainage system 40, wherein the transport fluid is collected in the further reservoir 42. So it is important to note that the monitoring string 12 has a (substantially) neutral buoyancy relative to the transport fluid 16, and that there is a controlled drag/fluid resistance to optimize the distribution of the tractive forces along the length of the string. Factually, it is the flow of the transport medium that propels the monitoring string 12 through the tubular structure 14.

Fig. 3 shows the second embodiment of the system when in operational use. In operational use the monitoring string 12 is coupled to a monitoring station 50, which may comprise a display 52, for example. The display 52 may then show when there is a hazardous event 99 (for instance a breach or leak) on the pipeline 100 as illustrated in the figure. This hazardous event 99 may then be detected by an affected sensor 12sa in the monitoring string 12, for example a temperature change, a pressure change or a vibration. The sensor 12sa then communicates with the monitoring station 50 via the communication bus 12.

The sensor 12sa (or a sensor segment) may arbitrate access to the communication bus directly to transfer information to the monitoring station 50. The monitoring station 50 may also poll the sensor 12sa (or sensor segment) periodically in order to receive up-to-date information from the sensor(s). The monitoring station 50 may automatically perform an action as a result of the sensor input, such as shutting down a pumping station connected to the pipeline 100 in the event of a breach, vibrations or increased pressure of the transmitted fluid (could happen in the event of hydrate formation in the pipeline 100).

The tubular structure 14 may be a separate part or an integrated part of the pipeline. The shape of cross-section of the tubular structure may be round, square or any other shape that allows for the most efficient utilization of the pipeline. It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be able to design many alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. Use of the verb "comprise" and its conjugations does not exclude the presence of elements or steps other than those stated in a claim. The article "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. The invention may be imple- mented by means of hardware comprising several distinct elements, and by means of a suitably programmed computer. In the device claim enumerating several means, several of these means may be embodied by one and the same item of hardware.

Claims

C l a i m s

1 . System (10) for monitoring a pipeline (100) for transporting a commodity,

c h a r a c t e r i s e d i n that the system (10) comprises a tubular structure (14) for being provided in, on or near the pipeline (100) extending over a predefined length of the pipeline (100), wherein the tubular structure (14) comprises a transport fluid (16) and a monitoring string (12) extending through the tubular structure (14), wherein the monitoring string (12) is designed with a plurality of buoyancy elements (12b) for creating a net buoyancy of the monitoring string (12) that is substantially neutral with respect to the transport fluid (16).

2. The system (10) according to claim 1 , wherein the system (10) further comprises, when being deployed, a reservoir (32) at the first end (14-1 ) of the tubular structure (14) for holding the transport fluid (16) and for providing the transport fluid

(16) to the tubular structure (14).

3. The system (10) according to claim 2, wherein the system (10) further comprises a pump (34) coupled between the reservoir (32) and the tubular structure (14), wherein the pump (34) is configured for pushing the transport fluid (16) into the tubular structure (14).

4. The system (10) according to claim 2 or 3, wherein the system (10) further comprises a drainage system (40) coupled to the other end (14-2) of the tubular structure (14) for receiving the transport fluid (16) therefrom.

5. The system (10) according to claim 2 or 3, wherein the system (10) further comprises a further tubular structure (14) coupled to the other end (14-2) of the tubular structure (14) and running parallel with the tubular structure (14) back to the first end for returning the transport fluid (16) back to the first end (14-1 ) for being drained there.

6. The system (10) according to any one of the preceding claims, wherein the monitoring string (12) comprises a supply and communication line (12sc) with a plurality of sensors distributed over its length and being electrically connected with said supply and communication line (12sc).

7. The system (10) according to claim 6, wherein said sensors are configured for sensing at least one of a group of properties of the commodity within the pipeline (100) comprising: temperature, pressure, and vibration.

8. The system (10) according to claim 7, wherein said sensors are at least partially provided in between the buoyancy elements (12b).

9. The system (10) according to claim 7 or 8, wherein said sensors are at least partially provided within the buoyancy elements (12b).

10. The system (10) according to any one of the preceding claims, wherein the system (10) further comprises, when in operational use, a monitoring station (50) coupled with the monitoring string (12) for carrying out the monitoring of the pipeline.

1 1 . The system (10) according to any one of the preceding claims, wherein the system (10) further comprises, when being deployed, a feeder wheel (18) at the first end of the tubular structure (14) for feeding the monitoring string (12) into the tubular structure (14) when it is pushed therein by the transport fluid (16).

12. Method of deploying a system (10) in accordance with any one of the preceding claims, c h a r a c t e r i s e d i n that the method comprises steps of:

inserting the monitoring string (12) in the first end (14-1 ) of the tubular structure (14);

supplying the transport fluid (16) into the first end (14-1 ), while the transport fluid (16) drags the monitoring string (12) further into the tubular structure (14), and

continuing supplying the transport fluid (16) until the other end (14-2) of the tubular structure has been reached.

13. The method according to claim 12, further comprising the step of:

draining the transport fluid at the other end of the tubular structure (14) simultaneously with the supplying of the transport fluid (16) at the first end (14-1 ).

14. The method according to claim 12 or 13, further comprising the step of:

facilitating the inserting of the monitoring string (12) with a feeder wheel (18) at the first end of the tubular structure (14), wherein the speed of the feeder wheel (18) is matched to the flow speed of the transport fluid (16).

15. The method according to any one of the preceding claims, further comprising, before the step of inserting the monitoring string (12), the step of providing the tubular structure (14) in or on a pipeline (100) for transporting a commodity.