WO2021127766A1

WO2021127766A1 - System for eliminating and removing hydrates and other blockages in undersea lines

Info

Publication number: WO2021127766A1
Application number: PCT/BR2020/050561
Authority: WO
Inventors: Henri FIORENZA DE LIMA
Original assignee: Petróleo Brasileiro S.A. - Petrobras
Priority date: 2019-12-27
Filing date: 2020-12-17
Publication date: 2021-07-01
Also published as: US20230040253A1; BR102019028092A2

Abstract

The present invention relates to a system for removing hydrates and other encrustations in undersea lines in oilfields. More specifically, the present invention relates to a system for eliminating and removing hydrates and other encrustations including independent traction modules fitted with load cells that control other traction modules, in which said traction modules are linked together alternately with lengths of armored cable. The system according to the present invention is intended for use in flexible or rigid lines with restricted or blocked flow.

Description

"FIGHTING SYSTEM AND REMOVAL OF HYDRATES AND OTHER BLOCKS IN SUBSEA PIPES"

Field of Invention

[0001 ] The present invention deals with a system for removing hydrates and other blockages in maritime pipelines in oil production fields. More specifically, the present invention deals with a system for combating and removing hydrates and other blockages comprising independent traction modules, equipped with load cells that act by controlling the traction modules, in which said traction modules are interconnected interspersed with sections of reinforced steel cable (steel cable with facilities for transporting electrical and/or hydraulic power in addition to, optionally, a circuit for fluid circulation, aiming to enable the availability of energy for its locomotion, as well as the activation of tools that this may load). The system of the present invention is applied in rigid or flexible ducts that present restrictions or blockages to the flow.

Description of the State of the Art

[0002] In the area of oil and gas exploration, with certain frequency, obstructions caused by hydrates or incrustations in maritime pipelines are observed. There are tools for accessing and removing these obstructions, but they do not have a great reach, especially in the horizontal part of the ducts, as they rely only on gravity for their positioning or limitations in relation to reach, due to friction between the cable and the wall of such pipelines.

[0003] The formation of hydrate generates a lot of damage to the exploration and production of oil and/or gas, restricting its flow and even obstructing production lines or services. Research and new developments have emerged to minimize the loss of production in oil wells.

[0004] It is not possible to use hydrate inhibitors in production or service lines after the blockage occurs, since hydraulic shims and liquid columns are formed that prevent the injection of these products chemicals at the necessary points. Hydrate formation is caused by high pressures and low temperatures, typical conditions in high depth oil wells.

[0005] Mechanical scale removal methods are carried out using PIGs, but not all lines are "pigable", requiring a specific constructability of equipment and even the efficiency of these devices is limited. There is still the possibility that the PIG will generate a block if it drags a lot of material with it. Furthermore, the use of PIG requires that there be flow for its displacement.

[0006] Another method used, the coiled tube, has difficulties due to the low capacity in relation to reach, especially in the horizontal part of the production pipelines, since it only relies on gravity for its positioning. Some equipment with its own traction is used in wells, but they are not suitable for pipelines due to the sharp curvatures, inflection points and the consequent friction, generating high loads to pull the power supply cable, as well as the stress on this cable for traction device recovery.

[0007] There are some systems that use two units, being a tractor module and an inspection module. As a rule, the tractor device is not activated to return, as it may "overrun" when it "runs over" the cable that gives it energy, enhancing its imprisonment inside the pipeline.

[0008] Equipment with its own means of locomotion are used, but they are not suitable for ducts comprising sharp curvatures, inflection points and high friction caused by the power cables which these equipments make use of, providing high effort to pull such a supply cable. energy, as well as high effort on said cable at the time of recovery of the equipment, if it is pulled back. [0009] The tools currently used to combat hydrate and other obstructions are: - Coiled tubing - tube positioned on a spool, and inserted from the top of a riser, where it accesses the suspended section of flexible or rigid pipes and wells in its vertical section and at the beginning of the horizontalization curvature. This device acts by gravity itself and the main limitation is the buckling of this tube, due to its high slenderness.

- Traction tools: used in the vertical, directional and horizontal section of wells, typically structures with a large radius of curvature, but without, or almost without, inflection points.

[0010] The document W02008111844A1 refers to a wire rope tractor. More particularly, it relates to a wire rope tractor comprising at least one drive wheel positioned on a displacement mechanism connected to the wire rope tractor, in which the displacement mechanism is arranged to hold the drive wheel in such a manner. tensioned against a well or pipeline wall. The displacement mechanism is at least rotatable or movable between a first position in which the drive wheel rests against the pit wall on one side of the tractor and a second position in which the drive wheel rests against the pit wall on the opposite side . In this sense, the wire rope tractor applies a tensile load that allows it to pull the rope it carries, moving through the well. Wire rope tractors have taken on considerable application in, for example, equipment and maintenance work on oil wells. Many wire rope tractors are supplied with sprockets that are tiltable. Often the attached cable is used to pull the wire rope tractor out of the pit.

[0011] The invention PI0005931 -3A is an inspection PIG. These equipment designed for long lines are mainly used in subsea or buried lines. The working mechanism is through high pressure fluids that drive the PIG movement. The action of the pressure fluid is on the annular cup positioned either at the front or rear, and is responsible for adjusting to the pipe diameter and promoting a certain sealing. Therefore, the fluid that drives the PIG acts on the cup cancel. Therefore, moved by the flowing fluid, this mechanism cannot work well in obstructed ducts.

[0012] Another type of PIG, based on a single body of polyurethane or foam-based, and which are used in situations of lines with various accessories, are not sufficient for cleaning some types of encrustations, especially hydrates due to the hardness of the inlay.

[0013] Intermediate tractor devices are not adopted due to the difficulty in synchronism between such devices, among other reasons.

[0014] Figure 10 shows an example of the coiled tubing system, which represents an embodiment of the state of the art, but which does not have a tractor at the end of the cable/rod/tube. This is only applicable in vertical or horizontal sections with short reach, since the cable/rod/tube with any tools descends by gravity. However, the drawing also illustrates what can be the winch drum that picks up the reinforced cable interspersed with traction elements, proposed in this document.

[0015] Thus, there is currently no tool or means that apply to the static section of pipelines, especially the flexible ones that have more accentuated curvature characteristics. Furthermore, static stretches are the most susceptible to problems that may require such interventions, being positioned on the seabed, typically far from the input end of such tools.

[0016] The present invention solves a problem that makes it impossible to move tractor devices in the reverse direction, this problem is the risk of the tractor overlapping the power and control cable to which the device is coupled. This is solved with a control system associated with measurements performed by load cells installed at the rear end of the tractor module (21 ), or at both ends, when applied to intermediate modules (20). Guaranteed a minimum value of traction in each cell, the traction modules can act in a synchronized way with the retraction of the cable, increasing or decreasing the speed of advance or retreat of each module, ensuring that the cable always remains in tension. Brief Description of the Invention

[0017] The present invention relates to a system for combating and removing hydrates and other encrustations comprising independent traction modules arranged in series, and each traction module is coupled to the following traction module by a segment of reinforced cable.

[0018] The traction modules (tractors), modules responsible for traction of the cable segments, are capable of not only being drivers or acting for traction, but also as if they were effort measurement modules. In this way, the values of stresses caused by axial loads on the cables are not cumulative in a single cable. Thus, it became possible to increase the concentrated load in a single module, and therefore, becoming more effective in reaching the points of interest for incrustation removal.

[0019] With this there is an advantage over traditional PIGs and other technologies, as large traction loads are not required in cables or systems that use booster fluids with very high pressures. In addition, the cable that interconnects the tractor system contains an umbilical inside for electrical, hydraulic, liquid circulation and cables for collecting information from sensors.

Brief Description of Drawings

[0020] The present invention will be described in more detail below with reference to the attached drawings, which in a non-limiting way to the inventive scope, represents a preferred mode of execution. So, you have:

- Figure 1 illustrates the system of the present invention positioned within a flexible duct, with reach associated with the number of segments used;

Figure 2 illustrates a top view of the interconnection socket between reinforced cable segments of the present invention of the present invention;

Figure 3 illustrates a side view of the interconnection socket between reinforced cable segments of the present invention; - Figure 4 illustrates a side view of the rolling wheel used in coupling between sockets of the present invention;

- Figure 5 illustrates a top view of the connection between two sockets that interconnect two sections of reinforced cable comprising a bearing according to the present invention;

Figure 6 illustrates a side view of the connection between two sockets comprising a bearing according to the present invention;

- Figure 7 illustrates the angle lag that must ensure that rolling wheels touch the inner surface of the duct, ensuring reduced friction observed;

- Figure 8 illustrates a side view of an alternative configuration to the use of the wheels with sockets shown in Figures 2 to 6, where the set of wheels snap and are attached to the reinforced cable, in a two-part system;

- Figure 9 illustrates a top view of an alternative configuration, using the wheels, in the split system;

- Figure 10 illustrates the conventional configuration, using coiled tubing, a technology that is limited to wells or applications with small reach.

Detailed Description of the Invention

[0021] The present invention relates to a system for combating and removing hydrates comprising independent traction modules (20) arranged in series, and each traction module (20) is coupled to another traction module (20) following, by an armored cable segment (10), in addition to the end pull module (21) located at the end of the assembly.

[0022] The traction modules (20) and end traction module (21) of the present invention, also known as tractors, are preferably of the active type, that is, they comprise their own locomotion means, with electrical or hydraulic drive. Furthermore, the end-located traction module (21) comprises means for positioning tools to combat and remove hydrates and other blockages such as scale deposition. In addition, the traction modules (20) are equipped with load cells that comprise electronic devices and sensors whose function is to control and power the traction module (20) and the end (21).

[0023] The reinforced cable segments (10) are provided with tubings for the transport of fluids (hydraulics and chemicals) along their length, as well as electrical supply containing a plurality of conductive wires and for data transport, in the same way as the traction modules (20) and the end (21 ) themselves, which allows the transmission (electrical and hydraulic) to the next segment.

[0024] The reinforced cable segments (10) have, at its core, a layer containing a plurality of steel cables to meet the mechanical traction. Furthermore, the reinforced cable segments (10) comprise an outer sheath, preferably nylon or Teflon, and comprise a preferential length of up to five hundred meters, however this length may vary due to different conditions, such as the friction force per meter for a typical duct configuration, internal diameter, internal material and geometry, radius of curvature, average number of inflection points per km and the total distance to be reached.

[0025] The tractors or also traction modules (20) are interconnected intermittently with sections composed of reinforced steel cable segments (10) of steel, being also associated with the steel cable winch (30), so that the loads are always of traction, avoiding damage to the set of armored cables (10) and traction modules (20).

[0026] The reinforced cable segments (10), according to the present invention, provide for distances comprising approximately between 2 and 20 meters in length (not limited to), where, preferably, each segment comprises 2 to 20 meters of cable, and are coupled to the other segments through sockets (12) attached at their ends, as shown in Figures 2 and 3. [0027] Figures 3 and 5 show the sockets (12), which are structures comprising a "U"-shaped support , comprising two legs (13) with a hole (15) in each leg (13) of the "U". Coupling between two sockets comprises positioning the sockets (12) so that each leg (13) of one socket (12) is between the two legs (13) of the other socket (12). The coupling further comprises the introduction of a rolling wheel (14), as (Figure 4), comprising a hole (16), so that the holes (15) of all legs (13) of the two sockets (12 ), plus the hole (16) of the wheel (14) are aligned. The coupling between two sockets further comprises the introduction of a locking pin (17) in the holes of the sockets (12) and the wheel (14), functioning as an articulation axis between the sockets and an axle for the wheel (14).

[0028] The sockets (12) of both ends of a sub-segment of the segment (10) and, consequently, the wheels (14) must have a relative positioning with misalignment, or offset, of about 45° or about 90° to each other, as shown in Figure 7. This offset allows the reinforced cable segment (10) not to accommodate in a way that impairs the operation of said bearing (14).

[0029] Each socket (12) must have fluid (hydraulic and chemical) and electricity transmission facility, of the swivel type, in the same way as between the socket (12) of the end of the reinforced cable segment (10) that connects to the traction module (20).

[0030] The reinforced cable segments (10), between a traction module (20) and another, can reach lengths of up to 500 meters, therefore, the sockets (12) must resist high traction stresses. In this way, they are preferably made of material with sufficient strength to support the weight of at least three kilometers of such a set of cables. Said sockets (12) provide the connection between the reinforced cable segments (10) and a bearing (14), using locking pins and nuts. The sockets (12) at both ends must have a misalignment, or offset, of about 45° or about 90°, depending on the diameter of the bearing (14) and the length of each sub-segment. This delay allows the reinforced cable segment (10) not to accommodate in order to impair the operation of said bearing (14). [0031] In addition, the reinforced cable segments (10) may comprise steel wires in different assembly directions, thus preventing torsions from causing the said accommodation of the reinforced cable (10), even with the use of said offset of the sockets (12).

[0032] Alternatively, the need for sockets (12) with the aforementioned relative positions can be replaced by the alternative configuration, shown in Figures 8 and 9, that is, an alternative configuration composed of bipartite devices (22) bearing wheel bearings ( 24). Such devices comprise a split structure, which grips the reinforced cable (10), avoiding the need for sub-segmentation of said cable. In this case, there are no sub-segments, having only one pair of sockets (12), one at each end of each segment of reinforced cable (10), maintaining these, the need to have swivels in each of the sockets (12), to perform the interface between each end of the armored cable segment (10) and its respective module (20).

[0033] This split device (22) is secured by screws and nuts (23) on each side of the axle of the bearing wheels (24), containing two wheels on the same axle. There is no coupling between sub-segments, as there are no discontinuities in the reinforced cable segment (10). The distance between each of the split devices (22), in this case, can be adjusted as a function of the expected efforts related to friction.

[0034] The present invention also allows the use of state-of-the-art tractor devices, as long as they undergo miniaturization, in order to allow their use in subsea flexible pipelines, passing in more severe radius of curvature, incorporating great value and flexibility of use to these equipments. Figure 10 shows an example of the coiled tubing system, which represents an embodiment of the prior art, but which does not have a tractor at the end of the cable. This is only applicable in vertical or horizontal sections with short reach, since the cable with any tools descends by gravity. In the same figure there is a structure that represents a device that isolates the inside of the duct from the external environment, acting as a BOP (40) Blow Out Preventor and that needs be adapted to the passage of the traction tool (each of its segments) in addition to the wheel devices.

[0035] The BOP (40), typically used in drilling and intervention in wells, must have shear gate valves, in a way that allow the cutting of the cable, if this is necessary to avoid the return of uncontrolled fluids. [0036] It must also be easy to divert such flow, if any, to a safe place (vase, vent, etc.).

[0037] The present invention solves a problem that makes it impossible to move tractor devices in the reverse direction, this problem is the risk of the tractor "running over" the power and control cable to which the device is coupled. This is solved with a control system associated with measurements of load cells installed at the rear end of the most advanced tractor module, or at both ends, when applied to intermediate modules. Guaranteeing a minimum value of traction in each cell, the traction modules can act in a synchronized way both in the advance and in the retraction of the cable.

[0038] The system according to the present invention minimizes the problem of friction present in the solutions of the prior art using reinforced steel cable - steel cable containing hydraulic hose and/or electric cable to feed the traction equipment and accessories attached to it time that allows the segmentation of the cable so that it can be pulled by several modules that, activated synchronously, divide the loads generated by the friction between the cable and the internal walls of the duct.

[0039] The application according to the present invention is directed to rigid or flexible ducts that have restrictions or blockages to the flow, for its unblocking.

[0040] The associated use of controlled distributed traction and friction reducers in the reinforced cables (10) reduces the efforts to tolerable levels, allowing a reach of several kilometers from the platform where the pipeline is interconnected. With this, it is possible to combat blockages due to hydrate formation or incrustation deposition, allowing tools to access the duct at points with such blockages or restrictions, said tools consisting of, for example, mechanical removal equipment, application/circulation of chemicals, local heating generation, etc., coupled to the module positioned at the end of the first cable segment.

[0041] With the reduction of scale, there will be a reduction in the head loss to the flow during the production of wells, increasing their production potential and, in the case of hydrates, which usually restrict production totally, the return to production in much less time, when compared with conventionally adopted methodologies, for example, the use of probes associated with the depressurization of the pipeline.

[0042] Active intervention (made possible with the invention, for long distances) tends to accelerate the solution of the problem, not limited to passive solutions (typically adopted with the use of intervention probes), where "ice melts" are literally expected. ".

[0043] Thus, with the use of the system object of the present invention, it is estimated an order of magnitude with savings of approximately 90%, justifying its prompt adoption.

[0044] It should be noted that, although the present invention has been described with respect to the attached drawings, it may undergo slight changes, but not escaping from the embodiment presented.

Claims

1 - COMBAT AND HYDRATE REMOVAL AND OTHER LOCKS SYSTEM, characterized in that it comprises independent traction modules (20) arranged in series, and each traction module (20) is coupled to the following traction module (20) by a cable segment armed (10), sockets (12) or split device (22); and a BOP device (40);

2- FIGHTING SYSTEM AND REMOVAL OF HYDRATES AND OTHER LOCKS, according to claim 1, characterized by the traction modules (20) and the end (21) comprise means of own locomotion being by electric or hydraulic drive;

3- SYSTEM FOR COMBAT AND REMOVAL OF HYDRATES AND OTHER BLOCKS, according to claim 1, characterized in that the traction modules comprise means to position tools to combat and remove hydrates and scale deposition;

4-FIGHTING SYSTEM AND REMOVAL OF HYDRATES AND OTHER LOCKS, according to claim 1, characterized in that the means to position tools to combat hydrates is located in the end traction module (21);

5- SYSTEM FOR COMBAT AND REMOVAL OF HYDRATES AND OTHER LOCKS, according to claim 1, characterized in that the traction modules (20) and the end (21) are equipped with load cells comprising electronic devices and sensors;

6- SYSTEM FOR COMBAT AND REMOVAL OF HYDRATES AND OTHER BLOCKS, according to claim 1, characterized in that the reinforced cable segments (10) comprise segments preferably comprising 20 meters in length, but not limited to this length, and are provided with means for transporting fluids, powering and transporting data along its length;

7- SYSTEM FOR COMBAT AND REMOVAL OF HYDRATES AND OTHER BLOCKS, according to claim 1, characterized in that the reinforced cable segments (10) comprise coating preferably of nylon or teflon; reaching 500 meters between each traction module (20) or 20 and

(21);

8- FIGHTING SYSTEM AND REMOVAL OF HYDRATES AND OTHER BLOCKS, according to claim 7, characterized in that the segments comprise sockets (12) at their ends for coupling between each segment;

9- FIGHTING SYSTEM AND REMOVAL OF HYDRATES AND OTHER BLOCKS, according to claim 8, characterized by the sockets

(12) comprise a U-shaped support comprising two legs

(13) with a hole (15) in each leg (13) of the “U”;

10- SYSTEM FOR COMBAT AND REMOVAL OF HYDRATES AND OTHER LOCKS, according to claim 9, characterized in that the coupling between reinforced cable segments (10) comprises the positioning of the sockets (12) so that each leg (13) of a socket (12) it is between the two legs (13) of the other socket (12), which will have channels forming a rotating “swivel” link that will allow the transmission of hydraulic pressure and electrical signals;

11 - HYDRATE AND OTHER COMBAT AND REMOVAL SYSTEM

BLOCKS according to claim 10, characterized in that the coupling between reinforced cable segments (10) comprises the introduction of a rolling wheel (14) comprising a hole (16), so that the holes (15) of all the legs (13) of the two sockets (12), plus the hole (16) of the wheel (14) are aligned;

12- HYDRATE AND OTHER COMBAT AND REMOVAL SYSTEM

BLOCKS according to claim 11, characterized in that the coupling between reinforced cable segments (10) comprises the introduction of a locking pin (17) in the holes (15) of the sockets (12) and in the holes (16) of the wheel (14), functioning as a pivot between the sockets and an axle for the wheel (14);

13- FIGHTING SYSTEM AND REMOVAL OF HYDRATES AND OTHER BLOCKS, according to claim 12, characterized by the sockets (12) of both ends of a sub-segment of each reinforced cable segment (10) have a 90° angle between such sockets and their subsequent ones;

14- FIGHTING SYSTEM AND REMOVAL OF HYDRATES AND OTHER LOCKS, according to claim 1 to 7, characterized in that the split device (22) has the cylindrical body adjustable to the reinforced cable (10) and with a locking system by screws and nuts (23 );

15- SYSTEM FOR COMBAT AND REMOVAL OF HYDRATES AND OTHER LOCKS, according to claim 14, characterized in that the split device (22) contains at least 2 wheels interconnected to the same axis;

16- COMBAT AND HYDRATE REMOVAL AND OTHER BLOCKS SYSTEM, according to claim 15, characterized in that the disposition of the sockets (12) or the split devices (22) consist of a misaligned shape in relation to each other at any angle, preferably at angles of 45 ^Q or 90 ^Q .

17- COMBAT AND REMOVAL SYSTEM OF HYDRATES AND OTHER LOCKS, according to claims 1 to 16, characterized by an electronic system for controlling the speed of the wheels present in the traction modules (20) and the end (21) in order to ensure the existence of traction loads in the reinforced cable segments (10).