NO338954B1 - UNDERWELL BELL INTERVENTION SYSTEM AND PROCEDURE FOR PERFORMING A UNDERWELL BELL INTERVENTION - Google Patents

Description

UNDERWATER WELL INTERVENTION SYSTEM AND PROCEDURE FOR PERFORMING AN UNDERWATER WELL INTERVENTION

Introduction

The present invention relates to a system for intervention of an underwater petroleum well, and a method for carrying out an underwater well intervention.

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Published patent applications WO 2008/015387 and WO 2001/025593 describe methods for moving well fluids in a container used for storage and deployment of tools during underwater well interventions. This does not concern the present proposal, which describes a movement of fluids limited to the cavity between two shut-off valves.

Patent publication US2011094749 describes a well intervention system which is arranged for connection to an underwater wellhead assembly, where fluid for cleaning the system is passed through a tool storage package.

Patent publication US4331203 describes a system for installing or removing well equipment in or from an underwater well using a lubricator.

Summary

According to a first aspect of the invention, a method is provided for carrying out an underwater well intervention at an underwater well, the underwater well comprises an underwater valve tree with a well adapter and a well control package comprising at least one valve in a vertical bore, the method comprises the steps of : (a) assembling a wireline drum pressure vessel assembly assembly disposed on a lubricator package with a sluice chamber tube encapsulating a tool string and having at least one valve in the vertical bore and a connector; (b) lowering said assembly to said well control package and connecting the assembly to the well control package using said connector; (c) pressure testing between said valve in the well control package and said valve in the lubricator package; (d) opening the valve in the lubricator package and the valve in the well control package; (e) lowering said tool string into the well; (f) performing a well operation using said tool string in the well; (g) retrieving said tool string from the well back into the sluice chamber pipe; (h) closing the valve in the well control package; (i) closing the valve in the lubricator pack; (j) further pressure testing between said valve in the well control package and said valve in the lubricator package; (k) displacement of well fluid in the cavity between said two valves with a displacement fluid; (I) disconnecting said assembly comprising said lubricator package and said wireline drum pressure vessel assembly from said well control package at said connector; and (m) retrieving the disconnected assembly to the surface;

where step (k) is performed while the valve in the lubricator pack is closed.

The wireline drum pressure vessel assembly may include an enclosed traction winch.

The method can further include the use of a clean fluid bottle for local storage of the displacement fluid in the vicinity of the underwater valve tree, and a fluid transfer system to drive the fluid from the clean fluid bottle through the cavity to one of a collector bottle, the well or a production fluid outlet.

The well control package may be installed to the lubricator package at the surface, prior to performing steps (a) through (m).

One or both of the valve in the well control package and the valve in the lubricator package may be arranged to be able to cut over a line attached to the tool string.

The method can further include, after step (k), receiving flushed out well fluid in a collector bottle arranged on said lubricator package.

According to a second aspect of the invention, an underwater well intervention system is provided, comprising: an assembly of a wireline drum pressure vessel package on a lubricator package on said well control package, said lubricator package is for holding on a wireline a tool string in a sluice chamber pipe in the lubricator package, where the system is arranged to drive said assembly to a well adapter; a connector for connecting and disconnecting said well control package to and from said well adapter; - a first valve in said lubricator package; - a second valve in said well control package;

- a connector between said first and second valve; and

- a fluid transfer system arranged to move the well fluid in the cavity between the first and second valve,

where the well fluid is moved while the first valve is closed.

The well fluid can be moved using a displacement fluid.

The displacement fluid may comprise seawater from a seawater inlet.

The well control package may have a vertical bore and may include a lower shear/seal valve, and optionally an isolation shear seal ball valve, in the vertical bore.

Brief description of drawings

Various embodiments of the invention are described in the following, illustrated in the attached drawings and figures, where: Figure 1 is a system overview; Figure 2 is a representation of a composition in the system from fig. 1, during lowering to a well adapter; Figure 3 is a representation illustrating the assembly from fig. 2 after having

been sunk;

Figure 4 is a representation showing a crown plug as it is pulled

the step shown in fig. 3;

Figure 5 is a representation showing the crown plug from fig. 4 as it is collected

up to the lubricator, in a further step;

Figure 6 is a representation showing a further step where a cavity is flushed

with a clean flushing fluid;

Figure 7 is a representation showing a disconnected part of the assembly from fig. 2 to 6, after disconnection from a well management package; Figure 8 is a representation showing a subsequent step where the assembly from fig. 3 to 6 have been prepared with a new tool string for operating in the well; Figure 9 is a representation showing yet another step where the lubricator package containing the new string from fig. 8 is connected to the well control package; Figure 10 is a representation showing a further step where an isolation valve is opened and an inflow test of a shear seal valve is carried out; Figure 11 is an illustration showing a further step; Figure 12 is a representation illustrating the tool string from fig. 8 in a further step, brought up to a lock chamber pipe; Figure 13 is a representation that illustrates a disconnected assembly during retrieval to the surface; and

Figure 14 is a rough sketch of a quick connector.

Figure texts

Figure 1 provides a system overview. The system has a line drum pressure vessel package 100, a lubricator package 80, and a well control package 30.

The line drum pressure vessel package 100 has a line drum pressure vessel 101.

The lubricator pack 80 includes the following:

a first valve in the form of an upper shear seal ball valve 83;

a sluice chamber pipe 81;

a fluid transfer system 70;

a clean bottle 72 for flushing fluid;

a collection bottle 71 for well fluids;

an HPU 60; and

a second valve in the form of a lower shear seal ball valve 82.

The well control package 30 includes a third valve in the form of an isolation ball valve 34 and a fourth valve in the form of a lower shear seal valve 32.

The wellhead has a well adapter 10 arranged on a horizontal underwater valve tree 1. The well adapter 10 is provided with a kill/flush line 2, and a crown plug 3 is installed.

The system further includes an upper quick connector 102a, 102b between the line drum pressure vessel package 100 and the lubricator package 80. The system further includes an upper quick connector 36a, 36b between the lubricator package 80 and the well control package 30. Furthermore, the system further includes a lower quick connector lia, 11b between the well control package 30 and the well adapter 10. The system also has a pressure transmitter 84.

The system includes a tool string Sl, S2, which in fig. 1 is located in the lock chamber pipe 81.

An assembly including the line drum pressure vessel package 100 comprising a pressure vessel 101 is assembled mounted on a lubricator package 80 which is connector mounted on a well control package with a further connection for, all of the above to be prepared with a tool string sl, s2, to be lowered into the sea for connection to a well adapter on an underwater well head. It can be noted that the first valve 83 between the pressure vessel 101 and the cutting seal ball valve can be optional in the present invention. Figure 2 shows the above assembly, including the line drum pressure vessel package 100, the lubricator package 80 and the well control package 30, during lowering to the well adapter 10 installed on the subsea valve tree 1. In fig. 2 shows a cavity 35 between the second valve 82 and the third valve 83. The assembly is lowered using a handling wire 90. The tool string Sl is located in and is protected in the liquid-filled lubricator. Figure 3 illustrates the assembly after being lowered, the well control package being connected to the wellhead with the crown plug 3 present, and being pressure tested. The well control package 30 is connected to the well adapter 10. The third valve 34 and the fourth valve 34 are open. The second, shear seal, valve 82 in the lubricator pack 80 is closed. Pressure testing over the crown plug is performed. Figure 4 shows the crown plug as it is pulled, following the step shown in fig. 3. The second valve 82 on the lubricator is open, and the tool string Sl is lowered to pull the crown plug 3. Figure 5 shows the crown plug 3 being brought up to the lubricator, into the sluice chamber tube 81, in a further step. The fourth valve 32 [i.e. the lower shear/seal valve] is closed, and the other valve 82 [i.e. lubricator valve] is closed. The area between the fourth valve 32 and the second valve 82 [i.e. between the lower shear/seal valve and the lubricator valve] is drained, and the fourth valve 32 [i.e. lower shear/seal valve] is pressure tested. A pressure sensor 84 in the second valve 82 is provided for sensing pressure in an area between the second valve 82 and the third valve 34 in the cavity 35. The crown plug 3 is retrieved from its position in fig. 4 with a distance D. Figure 6 shows a further step where the cavity 35 is flushed with a clean flushing fluid F1C from the clean fluid bottle 72 (from the surface, or from a bottle, or seawater from the sea). Flushed fluid in the form of a well fluid F1P is collected in the collector bottle 71. This will allow disconnection of the second valve from the third valve, because the cavity fluid becomes clean and thus environmentally friendly. The third valve 34 is closed. A pressure test between the second valve 82 and the third valve 34 is performed. The cavity 35 is then flushed with an environmentally friendly fluid, between the second and third valves 82, 34. Figure 7 shows a disconnected part of the assembly after disconnection from the well control package 30. The part includes the lubricator package 80 and the line drum pressure vessel package 100. The disconnected part is shown with the crown plug 3 on its way to be brought up to the surface. The well control package 30 is shown with two valves closed, which form a pressure tested barrier on the well adapter 10. The lubricator package is disconnected from the well control package. The second, third and fourth valves 82, 34 and 32 are closed. The lubricator pack 80 and line drum pressure vessel pack 100 are brought up to the surface, as shown by arrow U. Figure 8 shows the subsequent step where the brought up to the surface assembly or a pre-assembled similar assembly 100, 80 has been prepared with a new tool string S2 for operation in the well. In fig. 8, the assembly is lowered as shown by arrow L. The new tool string S2 is installed in the lubricator and pressure tested at the surface. The line drum pressure vessel package 100 and the lubricator package, including the new tool string S2, are driven to the seabed S. The second, third and fourth valves 82, 34, 32 are closed. The well control package 30 is arranged on the well adapter 10, as in the preceding step in fig. 7. The clean fluid bottle 72 contains flushing fluid F1C. Figure 8 can also be illustrative of a first step in the method when a well control package 30 is installed on the well adapter 10 on the seabed valve tree 1 before commencement.

In fig. 9 shows yet another step where the lubricator package 80 containing the new string S2 is connected to the well control package 30. The isolation valve 34 and the lubricator valve 82 are pressure tested. Pressure testing between the second and third valves is therefore performed. The second, third and fourth valves 82, 34, 32 are closed. Figure 10 shows a further step where the isolation valve 34 is opened and the inflow test of the shear seal valve 32 is carried out. By doing this, the second valve 82 is closed, the third valve 34 is open and the fourth valve 32 is closed. Figure 11 shows a further step where the shear seal valve 32 is opened, the lubricator valve 82 is opened, and the tool string s2 is lowered into the well, as shown by arrow R, and used to perform a mechanical operation, a chemical operation or a logging operation in the well. The cable line from the drum to the logging string S2 can be a rope-like cable line with a very small permissible bending radius. In fig. 11, the second, third and fourth valves 82, 34, 32 are all open. Figure 12 illustrates the tool string S2 in a further step, brought up to the sluice chamber tube 81 in the lubricator and with the lower valve 82 in the lubricator pack 80 closed. Similar preparations as above can be made to test valves and clean the cavities before disconnecting the lubricator package 80 from the well control package 30. The well control package 30 can remain on the wellhead adapter 10 for subsequent installation of a crown plug 3 or a subsequent well intervention. Accordingly, the second valve 82 is closed, the third valve 34 is closed and the fourth valve 32 is closed. A drain is carried out between the second valve 82 and the fourth valve 32. The fourth valve 32 is inflow tested. The cavity 35 between the second and third valves is flushed clean with non-contaminating flushing fluid F1C below the second valve, and flushed well fluids F1P are retained in the collection bottle 71. The lubricator package 80 is then disconnected non-contaminating from the well control package 30. Figure 13 illustrates the disconnected assembly including the line drum pressure vessel assembly 101 and the lubricator pack 80 as they are brought up to the surface, as indicated by arrow U'. The tool string S2 is picked up into the sluice chamber tube 81 in the lubricator pack 80, the lower shear seal valve 32 and the lubricator valve 82 have been closed and drained. Shear seal valve 32 has been inflow tested, isolation valve 34 closed, cavity 35 has been flushed with non-contaminating fluid, and flushed well fluid has been collected in collection bottle 71. Lubricator package 80 has been disconnected from well control package 30 to achieve non-contaminating disconnection. No well fluid has been released to the seawater. Figure 14 is a rough sketch of the quick connector 36a, 36b or lia, 11b. The connector has an upper half "a" and a lower half "b". The connector 36a, 36b between the second and third valves 82, 34 is shown. The cavity has an inlet 73 and an outlet 74.

Embodiments of the invention

It is very important in underwater well intervention operations to ensure that there are always two pressure barriers between the well and the sea. In addition, it is absolutely necessary to test these barriers once they are established, before performing a subsequent operation. Thirdly, it is important to avoid pollution to the sea when disconnecting valve packages to retrieve them to the surface. The above precautions prevent leakage and contamination should one barrier accidentally fail.

In one embodiment of the invention, a method for carrying out intervention in underwater petroleum wells comprises the use of a well adapter 10, a well management package 30, a lubricator package 80 and a winch package 100, the winch package comprising a line drum pressure vessel unit 101. These are installed on a subsea valve tree 1. The well adapter 10 is the interface between the underwater valve tree 1 and the well control package 30, and may include hydraulic and electrical features in addition to the mechanical features. The well control package 30 is equipped with at least one valve 32 in the vertical bore. Additional valves can preferably be added for increased versatility and reliability. The lubricator pack 80 is similarly equipped with at least one valve 82 in the vertical bore, a sluice chamber tube 81 and a fluid transfer system 70. The sluice chamber tube 81 acts as a deployment chamber for a tool string sl during the start and end of the operation. The fluid transfer system 70 can be used for two purposes; a first purpose is to move the fluids in the cavity 35 between the closed valves 82, 34 respectively in the lubricator package and the well control package, and a second purpose is to be used to verify the integrity of the system. The lubricator pack 80 may also have a valve 83 in the vertical bore above the sluice chamber 81, which will be redundant with regard to the valves further down, and constitutes a reserve in case these are blocked by the tool string sl.

The procedure for underwater well intervention according to the invention begins with assembly of the winch package 100 and the lubricator package 80 which encapsulates the tool string sl. The tool string sl is attached to the lower end of the line wound on the winch drum. Said assembly 100, 80 is lowered to the well control package 30 installed on the underwater valve tree 1 by means of the well adapter 10, and then connected 36a, 36b (see fig. 8).

In one embodiment of the invention, the pressure integrity of the above connection 36a, 36b is validated using the fluid transfer system 70 to generate a monitored excess pressure in the cavity 35 between the lower valve 82 in the lubricator package and the upper valve 34 in the well control package (see Fig. 9 ).

It continues with all the valves in the lubricator package 80 and in the well control package 30 being opened. This can be done in a thoughtful way with integrity checks that follow each other at each step (please see Fig. 10).

When the pressure integrity has been confirmed over all, and the valves 82, 32, 34 are open, then the tool string sl is lowered into the well (see Fig. 10) by lowering using the winch in the line drum pressure vessel package 101. The tool string sl, s2 is then used to perform a well intervention inside the well before at least part of it is retrieved back into the lock chamber pipe 81, and the valves 82 in the lubricator package and the valves 32, 34 in the well control package 30 are closed.

The tool string includes elements that are mechanical, electrical, radiant, explosive or optical, or any combination of these. It can be used to activate actions or passively monitor conditions in the well. It may also include powered machinery such as well tractors and/or milling tools.

The fluid transfer system 70 is used to validate the pressure integrity of the said closed valves 82 in the lubricator package 80 and the valves 32, 34 in the well control package 30, and to move the fluids in the cavity 35 between the two mentioned valves 82, 34. The movement of fluids replaces the potentially contaminating well fluid which is enclosed in the cavity 35 with a non-polluting fluid (see Fig. 12).

The assembly 100, 80 of the lubricator package 80 and the winch package 100 can then be disconnected from the well control package 30 at the aforementioned connection 36a, 36b, and brought up to the surface without discharge of potentially polluting or harmful fluids to the sea (see fig. 13). The above procedure can be repeated with the same or other tool strings for different well intervention tools s2, s3, s4... for intervention operations according to the operator's wish.

In one embodiment of the invention, the winch package 100 comprises a traction winch 102 and a drum, encapsulated inside a pressure vessel unit 101. Such a line drum-pressure vessel arrangement is exemplified by published Norwegian patent NO333503 (application number NO20111219).

In one embodiment of the invention, the fluid transfer system 70 comprises a clean fluid bottle 72 for local storage of the non-polluting transfer fluid in the vicinity of the underwater valve tree 1. Said container is preferably used to bring the non-polluting transfer fluid from the surface to the seabed, thus eliminating the need for a dedicated fluid line from the surface. The movement of fluids from the cavity 35 between the two valves 82, 32 is done by driving non-polluting transfer fluid contained from the clean fluid bottle 71 through the cavity 35 to either a collector bottle 71, into the well or to a production fluid outlet. The driving mechanism for moving the transfer fluid can be a piston, a pump, use of differential pressure, or a combination of these. The driving mechanism intended to drive the displacement fluid can be secondarily used for integrity testing by generating a controlled overpressure.

In one embodiment of the invention, the well management package 30 is installed on the well adapter 10 on the seabed valve tree 1 before starting the method seen in fig. 8.

In one embodiment of the invention, the well control package 30 is installed on the lubricator package 80 at the surface, before the start of the method, as seen in fig. 2. The subsequent steps of the procedure are then adapted accordingly. The well adapter can be an integral part of either the well control package 30 or the underwater valve tree 1.

In one embodiment of the invention, at least one of the well control package's valve 32 or the lubricator package's valve 82 is arranged to be able to cut over the line attached to the tool string sl and/or the tool string sl itself.

In one embodiment of the invention, at least one of the valve 32 and the valve 82 in the lubricator package is a ball valve.

Claims (13)

1. Method for performing an underwater well intervention, said underwater well comprises an underwater valve tree (1) with a well adapter (10) and a well management package (30) comprising at least one valve (32) in the vertical bore); (Fig. 7) comprising the steps of: - assembling an assembly (100, 80) of a wireline drum pressure vessel assembly (100, 101) arranged on a lubricator pack (80) with a sluice chamber tube (81) enclosing a tool string (s2 ) and has at least one valve (82) in the vertical bore and a connector (36a, b); - lowering said assembly (100, 80) to said well management package (30) and connecting it using said connector (36a, b) to said well management package (30); (Fig. 8) - pressure testing between said well control package's (30) valve (32) and said lubricator's valve (82), (Fig. 8); - opening of said lubricator pack's (80) valve (82) and well control pack's (30) one or more valves (32, 34); (Fig. 9) - lowering said tool string (s2) into the well; (Fig. 10) - execution of a well operation using said tool string (s2) in the well, (Fig. 10) - retrieval of said tool string (s2) from the well back into the sluice chamber tube (81), (Fig. 11 ); - closing one or more valves (32, 34) of said well control package (30); - closing said lubricator pack's (80) valve (82); - pressure testing between said well control package's (30) valve (32) and said lubricator package's (80) valve (82); - displacement of the well fluids in the cavity (35) between the two mentioned valves (82 and 32) with a non-polluting fluid (F1C) [non-polluting compared to seawater] - disconnection of said assembly (100, 80) comprising said lubricator package (80) and said wireline drum pressure vessel unit (100, 101) from said well control package (30) at said connector (36a, b), and retrieving them to the surface. 2. Method according to claim 1, wherein said variable line drum pressure vessel unit (100, 101) comprises an encapsulated winch [capstan winch]. 3. Method according to claim 1 or 2, where a clean fluid bottle (72) is used for local storage of the non-polluting transfer fluid (F1C) in the vicinity of the underwater valve tree (1) and a fluid transfer system (70) to drive the non-contaminating fluid from the clean fluid bottle (72) through the cavity (35) to either a collection bottle (71), into the well or to a production fluid outlet. 4. A method according to any of the above claims, wherein the well control package (30) is installed to the lubricator package (80) at the surface, prior to the commencement of the method. 5. Method according to any of the above claims, wherein at least one of said well control package's valve (32) or lubricator package's valve (82) is arranged to be able to cut over the line attached to the tool string. 6. Method according to any one of the preceding claims, after the displacement of the well fluids in the cavity (35) between the two mentioned valves (82 and 32) with a non-polluting fluid (F1C) [non-polluting in relation to sea water ], retention of flushed well fluid (F1P) to a collector bottle (71) arranged on said lubricator pack (80). Device requirements 7. Underwater well intervention system comprising: - an assembly (100, 80, 30) of a wireline drum pressure vessel package (100, 101) on a lubricator package (80) on said well control package (30), said lubricator package (80) is for holding a cable line a tool string (sl, s2) in its lock chamber tube (81), and - arranged for driving said assembly (100, 80, 30) to a well adapter (10) (Fig. 1) and comprising a connector (11) for connecting and disconnecting said well control package (30) to and from said well adapter (10) (Fig. 2), - a first valve (for example lower shear seal ball valve (82, II)) in said lubricator package (80), - a second valve [ for example, insulating shear seal ball valve (32, III)] in said well control package (30), - a connector (36) between said first valve and said second valve, - a fluid transfer system (70) arranged for moving the well fluids in the cavity (35) between said first valve and said second valve 8. Device according to claim 7, comprising a well adapter (10) for installation on an underwater valve tree (1), said well adapter (10) arranged for receiving a well management package (30) on top of it, (Fig. 1), 9. Device according to claim 7 or 8, wherein said fluid transfer system (70) comprises a clean fluid bottle (72) for local storage of the non-polluting transfer fluid (F1C) in the vicinity of the underwater valve tree (1) 10. Device according to claim 7, 8 or 9, where at least one of the well control package (30) valve or the lubricator package (80) valve is a ball valve. 11. Device according to any one of claims 7 to 10, wherein said wireline drum pressure vessel package (100, 101) comprises - a motor-driven drum for said wireline and arranged to maintain a backward pull on said wireline, - a motor-driven winch [capstan winch] for lowering and raising said line with said tool string (sl, s2) in said lubricator and said well, all within a pressure vessel which can be connected on top of said lubricator package (80). 12. Device according to any one of claims 7-11, wherein said non-polluting transfer fluid (F1C) consists of seawater (FICs) from a seawater inlet (72s). 13. Device according to any of the preceding claims, said well control package (30) comprises, in addition to said at least one valve (32) in the vertical bore, a lower shear/seal valve (32) and optionally an isolation shear seal ball valve (34) ).