Tool and methods for dissociating hydrate blockages in subsea lines by dewatering a vertical section of a line

Abstract

The present invention discloses a tool (100) for dewatering lines (102) for dissociating hydrate blockages (103), comprising at least one coupling assembly (110) for lowering and lifting the tool (100) within a line, a body assembly (120) comprising a hollow structure (121) and a central structure (122) on which a sealing assembly (140) is installed, a base assembly (130) comprising a retention mechanism (131) and a safety mechanism (132), and a fluid passage (150) extending through an interior space of the base assembly (130) and the body assembly (120) to the hollow structure (121). Methods for dissociating hydrate blockages (103) by dewatering lines (102) are further disclosed, using a tool (100) for dewatering a line, either alone or in combination with hydrate inhibitors (107).

Description

[0001] TOOLS AND METHODS FOR DISSOCIATION OF HYDRATE BLOCKAGES IN SUBMARINE LINES THROUGH DEWALING OF THE VERTICAL SECTION OF THE LINE

[0002] Field of invention

[0003]

[0001] The present invention falls within the technical field of techniques for removing hydrate blockages formed in submarine pipelines. More specifically, the present invention relates to a tool and methods for dewatering pipelines to dissociate hydrate blockages.

[0004] Fundamentals of the invention

[0005]

[0002] Deep offshore oil wells (greater than 500 m) can be obstructed by hydrates formed in the production or injection lines. A hydrate is a crystalline compound of water and some light hydrocarbons that forms under high pressure and low temperature conditions (a common condition in deep water). The formation of this compound is a critical operational problem in offshore oil wells, as the hydrate prevents the flow of oil.

[0006]

[0003] Clearing an offshore oil extraction pipeline blocked by hydrate, for example, 2 km from the platform and 3 km below the sea line, is a significant technical challenge. Some techniques currently employed aim to mitigate this problem, including:

[0007]

[0004] Injection of hydrate inhibitors such as methanol or monoethylene glycol, which can be applied in a line to prevent hydrate formation, or dissolve existing hydrates. These hydrate inhibitors act by modifying the thermodynamic conditions necessary for hydrate formation.

[0008]

[0005] Line heating, which involves implementing heating systems along the extraction line, which can help raise the temperature above the hydrate formation point, dissolving existing blockages. This technique can be implemented using electric heating cables or hot fluid circulation.

[0009]

[0006] Pressure reduction (depressurization) in the extraction line, which can destabilize the hydrates, separating them into water and gas. This can be achieved through the controlled opening of valves (chokes) in the lines to relieve pressure. This technique may involve unilateral depressurization from the platform; however, there is no guarantee of effectiveness and it does not work if there is a sufficient fluid column above to keep the fluid within the hydrate envelope (pressure and temperature conditions in which the compound is thermodynamically stable). It may also involve depressurization with a flexible tube from the platform. However, this is only applied in very specific cases, due to the weight of the necessary equipment (around 40 tons). Alternatively, the method may involve unilateral or bilateral depressurization with a probe from the wet Christmas tree (WCT) and from the platform.However, this incurs very high costs, and the difference in elevation between the ANM (Automatic Mining Area) and the base of the riser cannot be too great. Furthermore, the procedure does not work if there is a sufficiently large column of fluid above to keep the fluid within the hydrate envelope.

[0010]

[0007] Application of shock waves or vibrations involves the application of shock waves or vibrations, which can be used to break down hydrates without damaging the extraction line (experimental technique).

[0011]

[0008] Injection of CO2 or N2, which can alter the chemical composition around the hydrate, helping to dissolve it, or prevent its formation. However, this technique has low drag speed, high operating cost, and requires large support equipment.

[0012]

[0009] Nitrogen Generating System (NGS). This technique has not yet been proven in the field for this application, having only been qualified for scenarios where the produced fluid has little water and, furthermore, is expected to have low efficiency in fluid removal in very deep scenarios.

[0013]

[0010] Removal of the blocked line using a pipe-laying vessel and removal of the hydrate on the surface. Extremely costly and high operational risk technique.

[0014] State of the art

[0015]

[0011] In the State of the Art there are some documents focused on systems / devices for hydrate breaking in subsea systems and for pipeline dewatering.

[0016]

[0012] Document US10641065 discloses a method for reducing fluid pressure within subsea equipment. The method includes the steps of: (a) providing a pipe, (b) placing the pipe on the seabed, (c) providing a connector, (d) connecting the pipe to the subsea equipment via the connector, and (e) extracting fluid from the subsea equipment via the connector and into the pipe. The document also discloses an apparatus for reducing fluid pressure within subsea equipment by extracting fluid from the subsea equipment through a flexible pipe. However, this document is directed at subsea equipment, not flexible pipes, and is typically incapable of clearing a flexible pipe. Furthermore, with the equipment in question, it would not be possible to perform depressurization from the Stationary Production Unit. Finally, the method indicated here would not be applicable for clearing a hydrate blockage in a production line.

[0017]

[0013] The document Oil States Industries - Well Servicing Equipment - Guiberson Catalog, accessible at https: / / oilstates.com / wp-content / uploads / OSGuibersonProductCatalog.pdf, discloses swab cups and is aimed at promoting hydrocarbon production during formation testing in low-productivity wells or promoting fluid removal in gas wells. To this end, the tools in the catalog lift fluids from the well to the surface using, for example, a wireline. This fluid lift aims to reduce hydrostatic pressure at the bottom of the well and thus decrease the pressure difference between the reservoir and the inside of the well, allowing production to occur and enabling formation testing. The catalog reveals models of elastomeric seals with different geometries and also sinker bars to assist in lowering the tool, if necessary.Furthermore, the document reveals the option of using overload relief valves, which act as bypass valves to release excess fluid column, preventing overloading of cleaning cups when lifting heavy loads. However, this equipment is designed for a different application, namely promoting fluid production or removing fluid in gas wells. Even though they have been in common use for many decades, their application has never been considered for breaking up hydrates, so it doesn't seem obvious to a technician in the field. In addition, the tools in the catalog have a geometry that is poorly suited to handle the undulations of flexible pipelines. Furthermore, they cannot significantly vary their diameter to overcome restrictions. Finally, the tools in the catalog lack integrated mechanisms to assist descent and safety mechanisms integrated into the tool.

[0018]

[0014] Document US5462115 discloses a swab mounted in a mobile manner inside a well casing that automatically removes fluid from the well when the pressure accumulated at the bottom of the casing reaches a predetermined amount to lift the swab inside the casing. Again, this is equipment designed for a different application with limitations similar to the previous tool.

[0019]

[0015] Document US5462115 discloses oil and gas well swabs, particularly a dynamic seal for maintaining gas-tight contact between the moving swab and the well casing. The seal includes a booster tube and a flexible ring, having an upper throat portion that fits complementarily into the outside of the booster tube and a lower bell-shaped skirt portion that engages with the well casing. Again, this is equipment designed for a different application with limitations similar to the previous tools.

[0020]

[0016] In view of the disclosure of the State of the Art, the characteristics and advantages of the present invention will become clear from the detailed description below and with reference to the accompanying drawings.

[0021] Brief description of the invention

[0022]

[0017] The present invention discloses a tool for dissociating hydrate blockages in subsea pipelines by dewatering the vertical section of the pipeline, comprising at least one coupling assembly for lowering and raising the tool within a pipeline, a body assembly comprising a hollow structure, a central structure in which a sealing assembly is installed, a base assembly comprising a retention mechanism and preferably a safety mechanism, and a fluid passage that runs through an interior space of the base assembly and the central assembly to the hollow structure. Furthermore, methods for dissociating hydrate blockages by dewatering pipelines using a dewatering tool, either alone or in conjunction with hydrate inhibitors, are disclosed.

[0023] Brief description of the figures

[0024]

[0018] In order to complement the present description and obtain a better understanding of the characteristics of this invention, a set of figures is presented in which, in an exemplary, non-limiting manner, its preferred embodiments and some alternative configurations are represented.

[0025]

[0019] Figure 1 illustrates a schematic sketch of a Stationary Production Unit (SPU) for operating the tool of the present invention and a line connected to it containing a hydrate obstruction.

[0026]

[0020] Figure 2a shows a schematic of a line (e.g., a flexible duct) containing fluid inside.

[0027]

[0021] Figure 2b shows a schematic of the tool being lowered into the line.

[0028]

[0022] Figure 2c shows a schematic of the tool being positioned below the fluid level, then activated to expand and create a seal in the piping.

[0029]

[0023] Figure 2d shows a schematic of the tool being moved to the surface, bringing with it a column of fluid above it.

[0030]

[0024] Figure 3a shows a general external view of the tool, in a configuration with less shrinkage capacity (small diameter variation).

[0031]

[0025] Figure 3b shows a cross-sectional view of the tool, in a configuration with less shrinkage capacity (small diameter variation).

[0032]

[0026] Figure 3c shows an external view of the tool, in an alternative configuration with less shrinkage capacity.

[0033]

[0027] Figure 3d shows a cutaway view of the tool, in an alternative configuration with less shrinkage capacity.

[0034]

[0028] Figure 4a illustrates a sectional view of a sealing geometry in a V configuration, for use in the configuration with small variation in tool diameter.

[0029] Figure 4b illustrates a sectional view of a sealing geometry in a cup configuration, for use in the configuration with small variation in tool diameter.

[0035]

[0030] Figure 4c illustrates a cross-sectional view of a sealing geometry in a sliding hemisphere configuration, for use in the configuration with small variation in tool diameter.

[0036]

[0031] Figure 4d illustrates a sectional view of a sealing geometry in a V-shaped configuration with a membrane, for use in the configuration with small variation in tool diameter.

[0037]

[0032] Figure 4e illustrates a cross-sectional view of a sealing geometry in a cylindrical configuration, for use in the configuration with small variation in tool diameter.

[0038]

[0033] Figure 4f illustrates a cross-sectional view of a sealing geometry in a non-slip ball configuration, for use in the configuration with small variation in tool diameter.

[0039]

[0034] Figure 5a illustrates an isometric view of a sealing geometry in a V configuration, for use in the configuration with small variation in tool diameter.

[0040]

[0035] Figure 5b illustrates an isometric view of a sealing geometry in a cup configuration, for use in the configuration with small variation in tool diameter.

[0041]

[0036] Figure 5c illustrates an isometric view of a sealing geometry in a sliding hemisphere configuration, for use in the configuration with small variation in tool diameter.

[0042]

[0037] Figure 5d illustrates an isometric view of a sealing geometry in a cylindrical configuration, for use in the configuration with small diameter variation of the tool.

[0038] Figure 6 illustrates a general exterior view of the tool, in the configuration with large diameter variation, and of its operation to vary the diameter of a sealing module.

[0043]

[0039] Figure 7 illustrates a cross-sectional view of a preferred embodiment of the tool in the configuration with a large diameter variation, with details of its components.

[0044]

[0040] Figure 8a illustrates a cross-sectional view of a sealing geometry in a spherical configuration, normally contracted, for use in the tool configuration with a wide diameter range.

[0045]

[0041] Figure 8b illustrates an isometric view of a sealing geometry in a spherical configuration, for use in tool configurations with a wide diameter range.

[0046]

[0042] Figure 8c illustrates a cross-sectional view of a sealing geometry in an elliptical configuration, normally contracted, for use in the tool configuration with a wide diameter range.

[0047]

[0043] Figure 8d illustrates an isometric view of a sealing geometry in an elliptical configuration, normally contracted, for use in the tool configuration with a wide diameter range.

[0048]

[0044] Figure 8e illustrates a cross-sectional view of a sealing geometry in a V-configuration, normally contracted, for use in the tool configuration with a wide diameter range.

[0049]

[0045] Figure 8f illustrates an isometric view of a sealing geometry in a V-configuration, normally contracted, for use in the tool configuration with a wide diameter range.

[0050]

[0046] Figure 8g illustrates a cutaway view of a sealing geometry in a bellows configuration, for use in tool configurations with a wide diameter range.

[0047] Figure 8h illustrates an isometric view of a sealing geometry in a bellows configuration, for use in tool configurations with a wide diameter range.

[0051]

[0048] Figure 9 illustrates a wire tool system.

[0052]

[0049] Figure 10 illustrates the dewatering of a line, using the tool of the present invention in a wire tool system.

[0053]

[0050] Figure 11 illustrates an exemplary actuation of the tool in the configuration with a large variation in diameter, to expand or contract one or more sealing modules.

[0054]

[0051] Figure 12a illustrates a schematic of a submarine pipeline connected to a platform, with a flooded section and a hydrate blockage.

[0055]

[0052] Figure 12b illustrates a schematic of the introduction of the tool into the subsea line with a flooded section and a hydrate blockage.

[0056]

[0053] Figure 12c illustrates a schematic of removing a column of fluid from a vertical section of the line using the tool.

[0057]

[0054] Figure 12d illustrates a schematic of the injection of a chemical inhibitor denser than the fluid present in the line from a platform.

[0058]

[0055] Figure 12e illustrates a schematic of waiting for the chemical inhibitor to descend to a position where the hydrate block is located, and then moving the fluid column in the line to a substantially vertical section of the line.

[0059]

[0056] Figure 12f illustrates a schematic of how to introduce the tool into the subsea line in the fluid displaced to the vertical section with the tool.

[0060]

[0057] Figure 12g illustrates a schematic of removing a column of displaced fluid from the vertical section of the line using the tool.

[0058] Figure 12h illustrates a schematic of the dissociation of the hydrate blockage, after waiting a time for its destabilization.

[0061]

[0059] Figure 13 illustrates actual lines / ducts used in tests in a representative environment.

[0062]

[0060] Figure 14 illustrates an exemplary procedure for lifting the tool of the present invention.

[0063] Detailed description of the invention

[0064]

[0061] The present invention relates to a tool (100) and methods for dewatering lines for dissociating hydrate blockages.

[0065]

[0062] Gas hydrates are crystalline solids that form when water molecules create a crystalline structure stabilized by gas molecules within them. They form under specific conditions of high pressure and low temperature. Altering these conditions can destabilize and dissolve the hydrates, converting them back into water and gas.

[0066]

[0063] As exemplified in Figure 1, the invention can be applied for use in Stationary Production Units (101), or FPSOs (Floating Production Storage and Offloading). In this example, it is assumed that in a line (102) connecting the FPSO (101) to a Christmas tree (104) on the seabed there is a blockage by hydrate (103). The action of the tool (100) is most effective in the section of the pipeline where its trajectory is close to a vertical trajectory (riser section) of the line (102). For insertion / use of the tool (100) in the line (102), the vessel requires minimal support structures.

[0067]

[0064] It should be mentioned that the tool (100) can be applied to other types of Stationary Production Units (101), such as semi-submersible platforms. In addition, it can be applied to rigid pipelines or flexible pipelines.

[0065] Reducing the pressure to unblock an oil extraction line (102) blocked by hydrate (103) involves manipulating the physical (and / or chemical) conditions that stabilize the hydrates.

[0068]

[0066] It will be appreciated that reducing the pressure decreases the stability of gas hydrates, since the formation and stability of these compounds depend on a combination of high pressure and low temperature. Thus, by removing the fluid from the vertical section of the line (102), the tool (100) of this invention can reduce the pressure acting on the hydrate (103). This pressure reduction can potentially reach close to atmospheric pressure.

[0069]

[0067] The present invention aims to remove the fluid column (106) above a hydrate blockage (103), aiming at reducing pressure for hydrate dissociation and, consequently, resuming the flow of oil or gas inside the pipeline.

[0070]

[0068] Upon relieving the pressure, the crystalline structure of the hydrate begins to break down. Furthermore, with destabilization, the hydrates decompose into their constituent molecules, usually water and natural gas. As a result, the hydrate tends to dissociate, removing the physical blockage within line (102), and allowing oil and gas to flow normally again.

[0071]

[0069] The present invention performs the removal of the fluid column (106) above the hydrate (103) in an iterative manner, so that the pressure is reduced gradually and without abruptly altering the equilibrium. For example, 50 m of fluid column can be removed in each descent / ascent cycle of said tool (100). The height of the fluid column (to be removed) is related to the mechanical resistance of the tool, and may be greater or lesser according to the dimensions of the tool to be used.

[0070] In this sense, the pressure is gradually reduced until a dissociation pressure is reached at the location of the hydrate blockage (103) in the line. For the Brazilian scenario, for example, a value of 10 bar can be used as a reference. However, it will be appreciated that the dissociation pressure may vary according to the composition of the produced gas and water.

[0072]

[0071] Therefore, in general, the present invention discloses a dewatering tool (100), as illustrated in Figure 2, which must be inserted into a line / duct (102), such as a flexible duct containing fluid (106) inside, as illustrated in Figure 2a. The tool (100) is lowered into the line, with the fluid (106) inside the line passing through the inside or the side of the tool (100), until it is positioned below the fluid level, as illustrated in Figures 2b and 2c. The tool is then activated to expand and create a seal in the pipeline. This activation occurs preferably by the traction of the tool (100) itself combined with the weight of the fluid above the tool. These two factors, associated with the geometry of the tool's sealing assembly, press the tool's sealing assembly against the inner surface of the line (102), promoting the seal.Alternatively, there may be some form of electrical, hydraulic, mechanical, or pneumatic activation.

[0073]

[0072] Next, the tool (100) is moved to the surface bringing with it a column of fluid (106) above it, as illustrated in figure 2d. With this, the pressure below the dewatering tool is gradually reduced. The process of lowering the tool (100) and removing fluid is repeated several times until a sufficient amount of fluid is removed to reach the hydrate dissociation pressure.

[0073] After clearing the line (102), the dewatering tool (100) is retracted, if necessary, and then removed from the line.

[0074]

[0074] Optionally, the application of the tool (100) can occur in combination with the injection of hydrate inhibitors (107).

[0075]

[0075] Therefore, the present invention offers a solution with several advantages over traditional solutions. Among these advantages, the following can be mentioned, but not exhaustively:

[0076]

[0076] Economic and productivity advantages, since the use of the tool (100) in lines with hydrate blockages significantly reduces the time required to break up the hydrate, as it is a much simpler tool to mobilize. In addition, the cost will be significantly lower compared, for example, to the cost of a probe or PLSV.

[0077]

[0077] Health and safety advantages, as the use of the tool significantly reduces the number of man-hours exposed to risk (HHER). Currently, a large part of these hydrate breakdown operations is carried out using drilling rigs, vessels that typically require more than a hundred professionals to operate. With the tool, hydrate breakdown can be carried out with the allocation of fewer than ten professionals.

[0078]

[0078] Reliability advantages, as the use of the tool increases operational reliability, since any blockages caused by hydrate can be promptly removed with the use of the tool.

[0079]

[0079] Environmental advantages, since the use of the tool reduces emissions associated with the use of a probe to perform hydrate breakdown, or the use of a PLSV for line removal, cleaning and reinstallation.

[0080]

[0080] As illustrated in figures 3a - 3d and 7, an embodiment of the present invention discloses a tool (100) for dissociating hydrate blockages (103) in submarine lines by dewatering the vertical section of the line (102), wherein the tool (100) essentially comprises: a coupling assembly (110), a body assembly (120), a base assembly (130), a sealing assembly (140), and a fluid passage (150). It will be appreciated that said components are generally interconnected by means of screws and threads (male / female).

[0081]

[0081] It will be appreciated that the lines (102) can be any of the following: production lines, injection lines, and service lines. Typically, the lines (102) correspond to flexible ducts, multilayer ducts comprising an inner surface formed by an interlocked and therefore corrugated casing. Alternatively, those lines (102) can be rigid ducts, formed by steel pipes welded together. In both cases, the lines (102) typically have a vertical section, called the riser section, and a horizontal section, called the flowline section.

[0082]

[0082] Figures 3a - 3d and 7 illustrate the tool (100) in its preferred configuration and also illustrate some alternative configurations. Figures 3a to 3d show a tool (100) with less shrinkage capacity, typically used when there are no diameter reductions at the tool entry (in the line) or when these diameter reductions are small. On the other hand, figures 6 and 7 show a tool (100) with greater shrinkage capacity, used when there are more significant diameter reductions at the tool entry (in the line).

[0083]

[0083] Figure 3a illustrates the external view of the tool configuration (100) with the lowest shrinkage capacity and Figure 3b illustrates the cutaway view of the same tool.

[0084]

[0084] The base assembly (130) comprises a retention mechanism (131) and a safety mechanism (132). The retention mechanism (131) allows fluid to pass through the tool (100) during its descent and functions to retain the fluid column (102) above the tool (100) during its lifting. Said retention mechanism (131) is essentially composed of a ball (1311), a ball seat (1312) and a ball stop (1313).

[0085]

[0085] Thus, during the descent of the tool (100), the fluid that flows through the fluid passage (150) in an interior space of the base assembly (130), and from the central assembly (120) to the hollow structure (121), causes the ball (1311) to disengage from the ball seat (1312) and allow the passage of fluid. The ball stop (1313) acts as a stroke limiter for the ball (1311), preventing it from blocking the passage of fluid towards the hollow structure (121). Thus, the ball (1311) allows the passage of fluid only during descent.

[0086]

[0086] On the other hand, during the lifting of the tool (100), the pressure of the fluid column (106) causes the ball (1311) to engage with the ball seat (1312) and retain the fluid column.

[0087]

[0087] Additionally, during the lifting of the tool, and if a fluid column load (pressure) exceeds the capacity of the entire assembly, the safety mechanism (132) is activated. Thus, said mechanism allows fluid to pass from the top of the tool to the bottom of the tool if the pressure above the tool increases above a pre-established value.

[0088]

[0088] More specifically, the safety mechanism (132) comprises a spring (1321) disposed between the ball seat (1312) and a spring support (1322). The spring (1321) must be dimensioned according to the load capacity of the lifting system. Thus, if there is a fluid column above what the tool (100) can lift, the spring (1321) deforms and allows the ball seat (1312) to move downwards, thus enabling some of the fluid to be released and, consequently, reducing the load. Such a reduction in load can, for example, prevent the rupture of a tool (100) descent and lifting cable within a line (102).

[0089]

[0089] Figure 3c shows the external view of an alternative configuration of the tool (100) with less shrinkage capacity, and Figure 3d shows the cutaway view of the same configuration. The components are very similar to those presented in the previous paragraphs. The main difference is that, in this configuration, the tool (100) has a larger diameter to allow greater fluid passage during descent. In addition, the function of the sphere (1311) is performed by a set of spheres, instead of a single sphere. In this configuration, there is a set of external spheres (1311a), which allow the passage of fluid (106) through the interior of the tool. There is also a sphere (1311b) that performs the same safety function.

[0090]

[0090] The sealing assembly (140) is normally manufactured from an elastomer (rubber) and can assume different geometries. Figures 4a-4f show some of these geometries in cross-section, and Figures 5a-5d show some corresponding isometric views of Figures 4a-4f. In general, all configurations are designed in such a way that the weight of the fluid (106) above them presses one or more sealing elements of the sealing assembly (140) against the wall of the line / pipeline, increasing its sealing capacity. The configuration shown in Figure 4a and Figure 5a corresponds to a V-shaped configuration. Figure 4b and Figure 5b show a cup-shaped configuration, which differs from the previous one by having a small fold at the top. Figure 4c and Figure 5c show a sliding hemisphere configuration, which allows for greater pressure against the inner wall of the line (102). Figure 4d shows a V-shaped configuration with a membrane.This membrane aims to prevent the V from opening excessively. Figure 4e and Figure 5d show a cylindrical seal, which is less energized by the fluid but has greater flexibility to accommodate the undulations of an interlocked line casing. Finally, Figure 4f shows a non-slip ball configuration, which is less energized than the sliding ball but has greater structural robustness.

[0091]

[0091] Figure 6 illustrates a photo of a tool (100) with greater contraction capacity and Figure 7 shows a cutaway view of the tool, indicating the main components. The coupling assembly (110) enables the lowering and raising of the tool (100) within a line (102), comprising a connector (111) for coupling with a lowering and raising system. The coupling assembly (110) also comprises an adapter coupling (112) fixed between the connector (111) and the body assembly (120).

[0092]

[0092] Similar to the tool with less diameter reduction, it has a tube (121) with holes (1211) to allow fluid to exit, a hollow tube (150), a ball stop (1313), a ball (1311), a seat (1312) and a spring (1321). All this to allow the free passage of fluid during descent. Also to function as a safety element and to relieve the weight of fluid if necessary. Similarly, it has connectors above (112) and below (1322). On the other hand, unlike the other tool, it has a seal (140) capable of being significantly contracted by actuation and of expanding significantly, also by actuation, as illustrated in figure 6.

[0093]

[0093] Figures 8a-8h show some configurations for the sealing elements 140. Figures 8a, 8c, 8e and 8g show a cross-sectional view, and figures 8b, 8d, 8f and 8h show an isometric view. Figures 8a to 8f show configurations that are normally contracted and are inflated by a hydraulic fluid. Alternatively, a vacuum can be used to assist the contraction process. Figures 8a and 8b show a spherical configuration, figures 8c and 8d show an elliptical configuration, and figures 8e and 8f show a V-shaped configuration. All of them have a hydraulic expansion mechanism. Figures 8g and 8h show a mechanism similar to that shown in Figure 7, where the expansion and contraction of the sealing element is achieved by horizontal displacement of one of its sides.

[0094]

[0094] It should be mentioned that the lowering and lifting system can be any of the following: wireline, wireline, coiled tubing, robotic units, or any other system used in the oil and gas industry to perform a variety of operations in oil wells. These systems further comprise their respective well or pipeline operating assemblies; and these assemblies comprise tools or systems for preventing uncontrolled fluid flow and for tool movement.

[0095]

[0095] Preferably, the connector (111) of the tool (100) is a cable holder, which will be coupled to a wire tool system. As illustrated in Figures 9 and 10, a wire tool system is essentially a thin, smooth steel cable (wire), typically uncoated, which is inserted into the line to manipulate or install equipment inside the wells, as well as to perform measurements or interventions. Using the wire tool, the tool (100) can descend a predetermined length (e.g., 100 m) and then ascend the wire, bringing the fluid (106) from the line (102). The process is repeated as many times as necessary until the pressure in the line (102) is reduced to values ​​such that the hydrate (103) leaves its stability region. This emptying of the line section displaces the system outside the hydrate stability curve, promoting its dissociation.

[0096]

[0096] On the vessel there is a bypass shut-off spool (170), a pipe that typically has a bend (171) and which, under normal operating conditions, carries fluid from the line (102) to the process plant. This spool is connected to the vessel by two flanges (173 and 174), one flange (173) aligning the spool with the line (102) and another flange (174) aligning the spool with the process plant. The insertion of the tool (100) into the line (102) occurs through a bypass (172) in the spool. During the intervention, the spool carries the removed fluid (106) to an appropriate location in the process plant, such as the test separator or the drain tank (slop tank). This bypass shut-off spool may already exist on the vessel. However, in most cases, there is no pre-installed closing spool with a branch, there is only a closing spool. In these cases, a branch (172) can be made in the closing spool.Alternatively, the closing spool can be removed and replaced with a closing spool with a bypass.

[0097]

[0097] The wire tooling system is generally composed of:

[0098] a wire cabin (169), or slickline unit, comprising at least:

[0099] a wire drum (reel) where the wire is stored and unwound, and which is controlled by a system of brakes and motors that allows the controlled movement of the wire into and out of the well;

[0100] A measuring system, equipped with devices to measure the tension and length of the wire (weight and depth gauge), ensuring that the operator has precise control over the operation; and

[0101] a control panel, which is used by operators to monitor and adjust operations, including the speed of descent and ascent of the wire, as well as the applied tension, a wire cable (180), or slickline cable, which is composed of a thin, high-strength steel cable, which allows it to withstand the tensile loads during operations, wherein the steel cable generally comprises between 0.125 and 0.160 inches in diameter, and is used to lower and operate tools in the well. For the wire to enter safely, without the escape of hydrocarbons, a wire sealing system (164), also known as a stuffing box, is used;

[0102] A BOP (162), or Blowout Preventer, is a critical safety device installed above the bypass to control unexpected fluid flows that could lead to a blowout (uncontrolled flow of hydrocarbons). In the context of slickline operations, the BOP preferably comprises at least:

[0103] (Rare) shear rams, which are blades that can cut the slickline in an emergency, sealing the well; and sealing rams, which are used to seal the well around the slickline, allowing pressure containment while still allowing the slickline to enter and exit;

[0104] lubricators (163) and x-over (161), wherein these respectively comprise at least:

[0105] lubricators (163), being high-pressure tubes that allow the installation and removal of well tools without releasing well pressure;

[0106] an x-over (161), which connects the wire assembly (slickline) to the branch (172),

[0107] a wire sealing system (164), also known as a stuffing box, which has a sealing system and allows controlled insertion of the wire, without fluid escaping from the line to the atmosphere; and

[0108] a closing spool with a branch (170), as previously mentioned, which has a connector with the line (173), a connector with the process plant (174) and a branch (172) to allow tool access. Normally this spool has one or more bends (171).

[0109]

[0098] In addition to the components mentioned above, a hydraulic tool catcher (166) may be used. A hydraulic tool trap (167) may also be used. Finally, there may be a chemical injection point (165).

[0110]

[0099] Thus, to use the tool (100) of the present invention with a wire tool system, the operating procedure preferably comprises at least the following steps:

[0111] a) Preparation, in which the slickline unit is set up at the location, with all equipment, including the wire cabinet, BOP, and lubricators;

[0112] b) Installation and testing to ensure the integrity of the seal;

[0113] c) lowering the wire into the well along with the tool (100), continuously monitoring the tension and length;

[0114] d) execution of a planned task; and

[0115] (e) return of the wire and tool (100) for removal from the well, while the BOP and other equipment are depressurized and removed.

[0116]

[0100] Optionally, the descent and lifting system can be an electric cable (wireline). This electric cable can be either electric or mechanical, for performing subsurface operations. The use of the electric cable has the advantage of allowing the addition of bottom pressure and temperature sensors, enabling their reading in real time. With the use of the electric cable, the tool (100) can descend to a predetermined length (e.g., 500m) and then raise the tool (100) along the electric cable, bringing the fluid from the line. This emptying of the line section promotes the dissociation of the hydrate.

[0117]

[0101] Alternatively, a wire externally coated with insulating material can be used. This wire functions similarly to conventional wire, but allows for the sending and receiving of data through it. In some cases, it also allows for the remote operation of tools.

[0118]

[0102] Optionally, the lowering and lifting system can be a coiled tubing system. This coiled tubing is a continuous tube made of steel or composite materials, which is wound onto a reel and can be inserted into the well without the need to disassemble and reconnect segments, as occurs with traditional piping. With the use of coiled tubing, the tool (100) can descend a predetermined length (e.g., 500m) and then the tool (100) can be raised through the coiled tubing, bringing fluid from the line. This emptying of the line section promotes the dissociation of the hydrate.

[0119]

[0103] Alternatively, the lowering and lifting system may be a robotic unit. This robotic unit may be of the type that uses peristaltic motion to move within pipes / lines, being capable of exerting large forces. Using the robot, the tool (100) is lowered to a predetermined length (e.g. 1000m) by the robot itself and then the robot is raised with the tool (100), bringing the fluid from the line. Emptying the line section promotes the dissociation of the hydrate.

[0120]

[0104] If the lowering and lifting system is either a flexible tube or a robotic unit, it will typically be possible to bring in a larger quantity of fluid, reducing the number of ascents and descents.

[0121]

[0105] Figure 11 illustrates the operation of the tool (100), especially in relation to its contraction and expansion, in the configuration with the greatest variation in diameter. The body assembly (120) of the tool (100) generally comprises a hollow structure (121) and a central structure (122), in which a sealing assembly (140) is installed. The hollow structure (121) preferably comprises a plurality of holes or slots (1211) for the exit of a fluid that passes through the central structure (122).

[0122]

[0106] The central structure (122) is an elongated element, preferably cylindrical in shape, comprising grooves or rails on its exterior for the installation of the sealing assembly (140). The central structure (122) is preferably in the form of a robust cylinder that serves as the backbone of the tool (100). The interior of the central structure (122) preferably comprises a hollow space, which forms part of the fluid passage (150) of the tool (100).

[0123]

[0107] The sealing assembly (140) comprises one or more sealing modules preferably made of elastomeric or flexible composite materials, and comprises a quick-fit mechanism for installation in the grooves or rails of the central structure (122). The quick-fit mechanism comprises fittings or connectors that correspond to the grooves or rails of the central structure (122).

[0124]

[0108] It will be appreciated that the quick-release mechanism may consist of locking mechanisms such as bayonet locks or magnetic connectors, which allow for the quick exchange of one or more sealing modules. Optionally, the quick-release mechanism may also include levers or quick-release buttons that are accessible from the outside of one or more sealing modules, for manual manipulation or by intervention tools.

[0125]

[0109] As illustrated in Figure 6, it will be appreciated that one or more sealing modules / elements of the sealing assembly (140) can advantageously have their sealing diameter selectively reduced or expanded, from a resting state, by means of an actuation. Said one or more sealing modules can be expanded or contracted in response to applied pressure, to commands from the surface (remotely controlled), or in an automated (programmed) manner based on real-time data.

[0126]

[0110] The adjustment of the diameters is carried out by a drive means, which acts to modify the diameter / size of one or more sealing modules through any of a hydraulic, electric, pneumatic or mechanical drive, performing a stretching or compressing movement of one or more sealing modules.

[0127]

[0111] That is, the actuation means is capable of deforming one or more sealing modules in an axial direction (causing it to slide on an axis to deform) and thus deforming one or more sealing modules in a radial direction; to contract, undergo a reduction in diameter and subsequently recompose its expanded diameter (for example, return to a state of rest).

[0128]

[0112] Illustratively, the seals shown in Figures 8a to 8f are preferably expanded by hydraulic pressure and preferably contracted by removing that pressure. Alternatively, they can be contracted by applying a vacuum. On the other hand, the tools shown in Figure 7 and in Figures 8g and 8h are contracted or expanded by their axial displacement. This displacement can preferably be achieved by threads or, alternatively, by electric or hydraulic actuators. Figure 11 illustrates the process of contracting the tool by displacing its ends on the axial axis.

[0129]

[0113] Thus, it will be appreciated that, in the event of a branch being encountered that has a tool entry diameter smaller than that of the line / pipeline / riser, the drive means may act to reduce the diameter of one or more sealing modules or release them to reduce that diameter. After passing through the branch, one or more sealing modules may be released to an expanded state, or actuated to expand and seal against the inner wall of the line. Thus, operation in the pipeline may proceed, maintaining effectiveness in sealing and performing the functions of the tool (100). Optionally, in the case of remote actuation of the contraction mechanism, the tool (100) becomes capable of passing through reductions along the line (102). Although very uncommon in practice, these reductions are possible, so that the tool acquires an additional functionality.

[0130]

[0114] This passage enables the use of the tool (100) in a line with branches much smaller than the diameter of the line to be cleared. This is important because existing branches usually have a diameter smaller than the diameter of the line (102). In addition, in lines where there is no pre-existing branch, it is much easier and faster to manufacture a branch with a diameter smaller than the diameter of the line. This reduces the cost and well downtime.

[0131]

[0115] It will also be appreciated that different models of sealing modules can be used, depending on the conditions of the operations to be performed.

[0132]

[0116] Figure 11 illustrates this contraction and expansion mechanism of the tool (100). In this configuration, initially, the seal (140) is pressed by a screw and is in the expanded condition. In this expanded condition, the seal is radially expanded and axially contracted. By actuating this screw, the seal is progressively contracted until it becomes almost linear and with a diameter considerably smaller than the original diameter. In this contracted configuration, the seal is radially contracted and axially expanded.

[0133]

[0117] Furthermore, as described previously, the base assembly (130) comprises a retention mechanism (131) and a safety mechanism (132). The retention mechanism (131) allows fluid to pass through the tool (100) during its descent, and functions to retain the fluid column above the tool (100) during its lifting. Said retention mechanism (131) is essentially composed of a ball (1311), a ball seat (1312) and a ball stop (1313).

[0134]

[0118] Thus, during the descent of the tool (100), the fluid that flows through the fluid passage (150) in an interior space of the base assembly (130), and from the central assembly (120) to the hollow structure (121), causes the ball (1311) to disengage from the ball seat (1312) and allow the passage of fluid. The ball stop (1313) acts as a stroke limiter for the ball (1311), preventing it from blocking the passage of fluid towards the hollow structure (121). Thus, the ball (1311) allows the passage of fluid only during descent.

[0135]

[0119] On the other hand, during the lifting of the tool, the pressure of the fluid column (106) causes the ball (1311) to engage with the ball seat (1312) and retain the fluid column.

[0136]

[0120] Additionally, during the lifting of the tool, and if a load (pressure) of the fluid column (106) is above the capacity of the whole assembly, the safety mechanism (132) is activated.

[0137]

[0121] More specifically, the safety mechanism (132) comprises a spring (1321) disposed between the ball seat (1312) and a spring support (1322). The spring (1321) must be dimensioned according to the load capacity of the lifting system. Thus, if there is a fluid column (106) above what the tool (100) can lift, the spring (1321) deforms and allows the ball seat (1312) to move downwards, thus enabling some of the fluid to be released and, consequently, reducing the load.

[0138]

[0122] Optionally, the tool (100) may comprise the coupling of one or more weight bars (168), as illustrated in Figure 10. Said weight bar (168) is preferably located at a lower end of the tool (100). This configuration is preferred for ease of operation and safety of the assembly. However, the weight bar (168) may also be positioned at an upper end of the tool (100).

[0139]

[0123] The criterion for using one or more weight bars (168) depends on the operating conditions, since the tool (100) generally descends by gravity. However, if the fluid (106) inside the pipe is very dense or very viscous, one or more weight bars (168) may be used to speed up the descent process of the tool (100).

[0140]

[0124] The tool (100) may also include built-in sensors to monitor pressure, temperature, force and position, allowing precise adjustments during operation. Such sensors are typically positioned above the tool (100) and may only record data for future evaluation, or may transmit data via the electrical cable or via a coated wire.

[0141]

[0125] A second embodiment of the present invention discloses a method / process for dissociating hydrate blockages in submarine lines by dewatering the vertical section of the line, using said dewatering tool (100), and comprising at least the steps of:

[0142] a) introduce the tool (100) from a platform (101), into a flooded line (102); if necessary contracting the tool (100), passing through a derivation (172) and expanding the tool again;

[0143] b) lower the tool (100) below the fluid level (106) to a desired fluid column height;

[0144] c) activate the tool (100) to expand a sealing assembly (140) of this and create a seal against an inner wall of the line; and

[0145] d) move the tool (100) towards the surface, raising the fluid column (106) with it and directing said fluid to a pre-determined location in the process plant.

[0146]

[0126] The aforementioned method / process also includes:

[0147] e) Repeat steps a) - d) until a flooded section of the pipeline is emptied and / or until pressure sufficient for hydrate dissociation is reached.

[0148]

[0127] It will be appreciated that the dewatering tool (100) can be the tool (100) of the first preferred embodiment of the present invention.

[0149]

[0128] It will be appreciated that the method presented is perfectly applicable in descending lines. In these lines, the depth (bathymetry) of the line near the Stationary Production Unit (101) is greater than near the Christmas Tree (104). In them, the line initially descends until it meets the seabed and subsequently ascends to the depth of the Christmas Tree. This J-shaped geometry allows the procedure presented in the previous paragraphs to enable the emptying of practically the entire line (102) with the proposed tool. In this way, it allows the pressure to be reduced to near atmospheric pressure and therefore below the hydrate stability curve for most compositions and equilibrium conditions.

[0150]

[0129] However, the method has more limited application in ascending lines. In these lines, the depth (bathymetry) of the line near the Stationary Production Unit (101) is less than near the Christmas Tree (104). In these lines, the line initially descends until it meets the seabed and then descends even further to the depth of the Christmas Tree (104). This L-shaped geometry means that, even after emptying the vertical section of the line (102), there is still fluid (106) pressurizing the hydrate (103). In these cases, the pressure reduction may not be sufficient to move the hydrate (103) below its stability curve. For these cases, the third embodiment of the present invention is presented, which combines the emptying of the vertical section of the line (102) with the action of hydrate inhibitors (107).

[0151]

[0130] In this sense, it will be appreciated that the tool (100) can be used in combination with hydrate inhibitors (107) that are denser than the fluid present in the line.

[0152]

[0131] The aforementioned hydrate inhibitors (107) can act as agents to assist in hydrate dissociation (103). There are inhibitors denser than water, such as Monoethylene Glycol (MEG), Potassium Formate solutions (HCOOK) and Cesium Formate solutions (HCOOCs). These inhibitors can be injected into the line to descend by gravity and reach the hydrate after a certain time. Upon reaching the hydrate, these inhibitors can shift the hydrate stability curve.

[0153]

[0132] Alternatively, there are several other inhibitors, such as methanol, ethanol, diethylene glycol (DEG), triethylene glycol (TEG), sodium chloride (NaCl) solution, potassium chloride (KCl) solution, and calcium chloride (CaCl2) solution.

[0154]

[0133] In the case of using inhibitors (107) less dense than the fluid (106) present in the pipeline, such as ethanol, thickening agents may be used to allow their descent to the hydrate blockage. In the case of using highly viscous inhibitors (107), such as monoethylene glycol, rheology-modifying agents, such as viscosity reducers, may be used to allow faster descent. Thus, said hydrate inhibitors (107) may have their density increased by thickening agents or their viscosity reduced by viscosity reducers.

[0155]

[0134] It will be appreciated that such inhibitors (107) are not usually effective in isolation, since, when injecting these inhibitors, there is an increase in pressure. Thus, the shift in the stability curve is not usually sufficient to dissociate the hydrate.

[0156]

[0135] However, the combined use of hydrate inhibitors (107) with the tool (100) of the present invention promotes a combined action, providing a shift in the hydrate stability curve (103) and, subsequently, promoting a reduction in pressure. This action can promote faster hydrate breakdown and can also allow hydrate breakdown to occur in ascending lines.

[0157]

[0136] Therefore, in a third embodiment of the present invention, as illustrated in Figures 12a-12h, a method is disclosed for dissociating hydrate blockages (103) in submarine lines (102) by dewatering the vertical section of the line, using a dewatering tool (100), comprising at least the steps of:

[0158] a) perform fluid removal (106) from the vertical section of the line (102) using the dewatering tool (100) in an iterative manner (preferably following one of the procedures presented in the second embodiment of the present invention, as illustrated in Figures 12a, 12b and 12c); b) inject into the line the chemical inhibitor (107) denser than the fluid present in the line from the platform (Figure 12d);

[0159] c) wait a time (which can be simulated in different computational tools) for the inhibitor (107) to descend to a position where the hydrate (103) is located, so that it displaces the fluid column (106) present in the line to a substantially vertical section of the line (Figure 12e);

[0160] d) repeat step a), that is, perform the removal of the fluid (106) from the vertical section again with the dewatering tool (100) in an iterative manner (preferably following one of the procedures presented in the second embodiment of the present invention, as illustrated in figures 12f and 12g); and

[0161] e) wait a period of time (hours or days) for the hydrate block (103) to become destabilized and to check if its dissociation occurs (figure 12h).

[0162]

[0137] If it is found that hydrate blockage persists, the method may also include:

[0163] f) Repeat steps b) - e) above until the hydrate is dissociated (blockage is successfully removed).

[0164]

[0138] Preferably, step a) comprises the following sub-steps: a) introducing the tool (100) from a platform (101), into a flooded line (102); if necessary contracting the tool, passing through a branch (172) and expanding the tool again;

[0165] a2) lower the tool (100) below the fluid level (106) to a desired fluid column height;

[0166] a3) activate the tool (100) to expand a sealing assembly (140) of this and create a seal against an inner wall of the line; and

[0167] a4) move the tool (100) towards the surface, raising the fluid column (106) with it and directing said fluid to a pre-determined location in the process plant.

[0168]

[0139] Furthermore, the aforementioned additional sub-steps may also include the sub-step of:

[0169] a5) Repeat substeps a1) - a4) until the flooded section of the line is emptied and / or until a pressure for hydrate dissociation is reached.

[0170]

[0140] It will be appreciated that the dewatering tool (100) can be the tool (100) of the first preferred embodiment of the present invention.

[0171]

[0141] As illustrated in Figure 13, the invention was tested in a representative environment (real lines / pipelines) to evaluate its functionality, with positive results. Lines were positioned vertically and the proposed tool and its method / process of operation were tested. Figure 14 illustrates an exemplary procedure for lifting the tool, resulting in the elevation of a column of fluid.

[0172]

[0142] Thus, those skilled in the art will appreciate the knowledge presented here and will be able to reproduce the invention described in the embodiment presented and in other variants, covered within the scope of the appended claims.

Claims

CLAIMS 1. Tool (100) for dissociating hydrate blockages in submarine lines by dewatering the vertical section of the line, characterized in that it comprises: a coupling assembly (110) for lowering and raising the tool (100) within a line; a body assembly (120) comprising a hollow structure (121) and a central structure (122) in which a sealing assembly (140) is installed; a basic assembly (130) comprising a retention mechanism (131); and a fluid passage (150) that runs through an interior space of the base assembly (130) and the central assembly (120) to the hollow structure (121).

2. Tool (100), according to claim 1, characterized in that the sealing assembly (140) comprises one or more sealing modules that have their sealing diameter selectively reduced or expanded at the line inlet by a drive means.

3. Tool (100), according to claim 1 or 2, characterized in that it additionally has a safety mechanism (132), wherein said mechanism allows the passage of fluid from the top of the tool to the bottom of the tool if the pressure above the tool increases above a pre-established value.

4. Tool (100), according to any of the preceding claims, characterized in that the coupling assembly (110) comprises a connector (111) and an adapter coupling (112).

5. Tool (100), according to any of the preceding claims, characterized in that the hollow structure (121) preferably comprises a plurality of holes or slots (1211) for the exit of a fluid that passes through the central structure (122).

6. Tool (100), according to any of the preceding claims, characterized in that the central structure (122) comprises grooves or rails on its exterior for the installation of the sealing assembly (140).

7. Tool (100), according to any of the preceding claims, characterized in that an interior of the central structure (122) preferably comprises a hollow space, which forms part of the fluid passage (150) of the tool (100).

8. Tool (100), according to any of the preceding claims, characterized in that the sealing assembly (140) comprises one or more sealing modules preferably made of elastomeric or flexible composite materials, and comprising a quick-fit mechanism for installation in grooves or rails of the central structure (122).

9. Tool (100), according to any of the preceding claims, characterized in that the actuating means is capable of deforming one or more sealing modules in an axial direction and thus deforming one or more sealing modules in a radial direction; to contract, undergo a reduction in diameter and subsequently recompose its expanded diameter.

10. Tool (100), according to any of the preceding claims, characterized in that the retaining mechanism (131) is composed of a ball (1311), a ball seat (1312) and a ball stop (1313).

11. Tool (100), according to any of the preceding claims, characterized in that the safety mechanism (132) comprises a spring (1321) and a spring support (1322).

12. Tool (100), according to any of the preceding claims, characterized in that, optionally, the tool (100) further comprises weight bars (168) at a lower or upper end thereof.

13. Tool (100), according to any of the preceding claims, characterized in that it further includes incorporated sensors for monitoring pressure and position.

14. Tool (100), according to any of the preceding claims, characterized in that it further comprises a closing spool with a bypass (170), wherein said spool connects the line (102) to the process plant, wherein the spool contains a bypass (172) to allow the tool access to the line (102) and wherein the spool allows the fluids brought by the tool (100) to be directed to the desired location in the process plant.

15. Tool (100), according to any of the preceding claims, characterized in that it further comprises a wire tool system for moving the tool, comprising at least one BOP (162), a lubricator (163), a stuffing box (164), a wire spool and a weight and depth gauge.

16. Tool (100), according to any of the preceding claims, characterized in that it further comprises one of: an electric cable assembly, a flexible tube assembly or a robotic unit, for moving the tool; and that it further comprises its respective operating assemblies in wells or in pipelines; and wherein these assemblies comprise tools or systems for preventing uncontrolled fluid discharge and for moving the tool.

17. Tool (100), according to any of the preceding claims, characterized in that it can be used in combination with hydrate inhibitors (107) denser than the fluid present in the line.

18. Tool (100), according to claim 17, characterized in that the hydrate inhibitors (107) are one of: methanol, ethanol, monoethylene glycol, diet ylene glycol, triethylene glycol, sodium chloride solution, potassium chloride solution, calcium chloride solution, potassium formate solution and cesium formate solution.

19. Tool (100), according to claim 17 or 18, characterized in that said hydrate inhibitors (107) have their density increased by thickening agents or their viscosity reduced by the addition of rheology-modifying agents.

20. Method for dissociating hydrate blockages in submarine lines by dewatering the vertical section of the line, using a tool (100), wherein the method is characterized in that it comprises at least the steps of: a) introduce the tool (100) from a platform (101), into a flooded line (102); if necessary contracting the tool, passing through a derivation (172) and expanding the tool again; b) lower the tool (100) below the fluid level (106) to a desired fluid column height; c) activate the tool (100) to expand a sealing assembly (140) of this and create a seal against an inner wall of the line; and d) move the tool (100) towards the surface, raising the fluid column (106) with it and directing said fluid to a pre-determined location in the process plant.

21. Method according to claim 20, characterized in that it further comprises the step of: e) repeat steps a) - d) until the flooded section of the line is emptied and / or until a pressure for hydrate dissociation is reached.

22. Method according to claim 20 or 21, characterized in that the dewatering tool (100) is a tool as defined in any of claims 1 to 19.

23. Method for dissociating hydrate blockages in submarine lines by dewatering the vertical section of the line, using a dewatering tool (100), wherein the method is characterized in that it comprises at least the steps of: a) perform the removal of fluid (106) from the vertical section of the line (102) using the dewatering tool (100) in an iterative manner; b) inject the chemical inhibitor (107) which is denser than the fluid present in the line from the platform; c) wait for the inhibitor (107) to descend to the position where the hydrate (103) is located, so that it displaces the fluid column (106) to a substantially vertical section of the line; d) repeat step a); and e) wait a while for the hydrate block (103) to destabilize and check if dissociation occurs.

24. Method according to claim 23, characterized in that it further comprises the step of: f) Repeat steps b) - e) until the carbohydrate is dissociated.

25. Method according to claim 23 or 24, characterized in that step a) comprises the following sub-steps: al) introduce the tool (100) from a platform (101), into a flooded line (102); if necessary contracting the tool, passing through a derivation (172) and expanding the tool again; a2) lower the tool (100) below the fluid level (106) until a desired fluid column height is reached; a3) activate the tool (100) to expand a sealing assembly (140) of this and create a seal against an inner wall of the line; and a4) move the tool (100) towards the surface, raising the fluid column (106) with it and directing said fluid to a pre-determined location in the process plant.

26. Method according to claim 25, characterized in that step a) further comprises the sub-step: a5) Repeat steps a1) - a4) until a flooded section of the pipeline is emptied and / or until pressure sufficient for hydrate dissociation is reached.

27. Method according to any one of claims 23 to 26, characterized in that the dewatering tool (100) is a tool as defined in any one of claims 1 to 19.

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