1. Technical field

The present disclosure relates to a flapper rearrangement tool for being inserted into a borehole to rearrange a broken flapper inside a tubing retrievable subsurface safety valve and a method for rearranging a broken flapper inside a tubing retrievable subsurface safety valve.

2. Prior art

In the field of oil and gas production must be ensured that a reliable interruption of the oil and gas flow is possible in the event of maintenance work, safety-critical incidents, and for a production interruption in general. Otherwise, considerable environmental damage can result if oil and gas leaks uncontrollably into the environment.

Hence, ensuring well integrity is a central element in the field of oil and gas production. Regularly, well integrity is associated with maintaining well control with sufficient barriers. A central element for ensuring well integrity is that two independent well barriers are present at each stage of a well’s life. This is not only widespread industry practice, but is also required by various standards, some of which are international, e.g., ISO1653O.

Regularly used barriers include tubing retrievable subsurface safety valves which are also known as TR-SSSVs. These valves comprise a so-called flapper and a movable tube. The flapper is , which is movably mounted by a hinge and controls the oil and/or gas flow depending on the position of the movable tube. This functionality is further described in detail below.

A schematic tubing retrievable subsurface safety valve 80 is shown in Figs. 9a and 9b, with Fig. 9a showing the open condition and Fig. 9b showing the closed condition. To open the tubing retrievable subsurface safety valve 80 shown in Fig. 9b, a liquid is pressed into a reservoir 82 via a hydraulic control line 81. When a sufficient pressure is applied, a movable tube 83 is displaced downwards against a spring element 86 and a flapper 85 is rotated into a pocket 84, as illustrated in Fig. 9a. When the pressure in the hydraulic control line 81 drops below a threshold, the liquid in the reservoir 82 is displaced into the hydraulic control line 81 and the movable tube 83 is pushed back again upwards by the spring element 86. Thereby, also the flapper 85 moves back to the horizontal closed position, e.g. by means of a corresponding spring at the hinge.

However, it has shown in practice that said flappers sometimes break off at their hinge in tubing retrievable subsurface safety valves. The flapper then remains functionless inside the tubing retrievable subsurface safety valve. As a result, the safety function as a barrier can no longer be guaranteed and/or only limited production can take place as the flapper blocks at least partially the liquid flow. In addition, access to the area of the borehole that lies below the tubing retrievable subsurface safety valve is restricted. Hence, no replacement barrier can be placed in this area of the borehole to restore well integrity.

In practice, the problem of a broken flapper is regularly solved by removing the flapper from the tubing retrievable subsurface safety valve. This requires workover operations and/or the installation of a rig. For example, a drilling tool is inserted into the borehole to crush the flapper. Another option is to erode the broken flapper, exemplarily by means of thermite. The existing solutions dealing with broken flappers are usually material, labor, and/or time consuming and therefore often very costly.

Thus, it is an object of the present disclosure to provide a tool and a method that overcome the aforementioned drawbacks at least partially.

3. Summary of the invention

This object is achieved, by a flapper rearrangement tool and a method for rearranging a broken flapper inside a tubing retrievable subsurface safety valve, as defined in the independent claims. Further aspects of the present disclosure are defined in the dependent claims.

In particular, the object is achieved by a flapper rearrangement tool for being inserted into a borehole to rearrange a broken flapper inside a tubing retrievable subsurface safety valve. Said borehole may be used to produce oil and/ or gas. Moreover, the borehole may comprise a tubing being configured to guide oil and/or gas from a subsurface reservoir towards the earth’s surface. Further, the borehole may be provided with other well completion components such as casing liners. The tubing retrievable subsurface safety valve inside the borehole may be attached to said tubing being configured to guide oil and/ or gas.

The tool comprises a substantially cylindrical guiding portion having a first radius and a longitudinal axis. Said cylindrical guiding portion may serve to align the longitudinal axis of the tool along a centre axis of the borehole and particularly of a centre axis of the tubing within the borehole. Further particularly, the first radius may be adapted to an inner diameter of the tubing.

Moreover, the tool comprises a tip portion at a first end of the tool for establishing initial contact with the broken flapper, wherein the tip portion is radially displaced outwards relatively to the longitudinal axis by a second radius. This can ensure that the tool does not establish initial contact with a centre point of the flapper but an eccentric point. This has proven to make it easier to move the flapper from its rest position than via a central contact. Particularly, as the eccentric point may be pushed down, and another area of the flapper moves up as a result.

Further, the tool comprises a rearrangement portion for rearranging the broken flapper, wherein the rearrangement portion is arranged between the tip portion and the guiding portion and provides a contact surface for moving the broken flapper. The contact surface is shaped such that when moving the tool against the broken flapper, after establishing initial contact with the tip portion, it is first erected and after erecting pushed into a pocket of the tubing retrievable subsurface safety valve. Said pocket may be the portion of the tubing retrievable subsurface safety valve, where the flapper was arranged when it was still working and in an open state. Pushing the flapper into the pocket requires the flapper being moved radially outward as see from the longitudinal axis of the cylindrical guiding portion.

Furthermore, the tool comprises a fastening means at a second end of the tool for fastening the tool to a support means that allows the tool to be inserted into the borehole. The support means may comprise a wireline and/or a slickline. For example, the fastening means may comprise a thread to which the support means is attached by means of a corresponding counter-thread.

Tubing retrievable subsurface safety valves which are also referred to as TR-SSSVs are known and widely used in the industry. A respective example is described above in the prior art section with reference to Figs. 9a and 9b of the present disclosure. Further, also the disadvantage of said tubing retrievable subsurface safety valves that the flapper may break off and remain inside the valve is commonly known. Throughout the present disclosure “a broken flapper” may be referred to as a flapper of a tubing retrievable subsurface safety valve which has come loose from its suspension inside the valve and may reside in a lower area of the valve. It is understood that flappers may break off from their suspension due to a variety of reasons e.g., fatigue, slick line operations, and/or coiled tubing operations.

The described flapper rearrangement tool according to the present disclosure has several advantages, wherein three of them are described in the following.

First, workover operations and/or the installation of a rig can be avoided. For example, it is not necessary to insert a drilling tool into the borehole to crush the flapper. Consequently, the effort and time required to remove a broken flapper are reduced.

Second, since the flapper is stowed inside the tubing retrievable subsurface safety valve, it can be avoided that during crushing the flapper other parts, such as the tubing of the borehole, are damaged. Moreover, no loose parts which may result from crushing the flapper can lead to damages. Hence, in summary, the described flapper rearrangement tool allows for an increased safety.

Third, it has also been shown that it is possible to reliably remove the flapper in one step. When removing a broken flapper by means of drilling or thermite, it is likely that parts of the flapper remain in the valve and an additional intervention is necessary. For example, because a drill rim remains in the valve. Thus, the present tool allows for increased reliability.

Preferably, the tip portion and the rearrangement portion are integrally formed. “Integrally formed” may be referred to the aspect that theses portions are made out of one single part. Accordingly, the tip portion may continuously transition into the rearrangement portion. This may avoid a complex assembly of the tool.

Preferably, the tip portion and/or the rearrangement portion are formed by an oblique cut cylinder. The contact surface maybe formed by the oblique cut surface. It is understood that the oblique cut surface not necessarily requires to be planar.

Particularly, the oblique cut surface may be shaped as described throughout the following.

Preferably, the contact surface comprises a first area adjacent to the tip portion, and a second area spaced apart from the tip portion along the longitudinal axis such that the first area is arranged between the second area and the tip portion, wherein a first inclination angle between the first area and the longitudinal axis is larger than a second inclination angle between the second area and the longitudinal axis. When determining the first inclination angle and/or the second inclination angle, preferably the acute angle is determined respectively. The first inclination angle being larger than the second inclination angle has proven to facilitate erecting the flapper and then urging it into the pocket.

Preferably, the first inclination angle lies in a range from 15 ⁰ to 35 ⁰ , optionally from 17 ⁰ to 30°, further optionally from 18° to 28°, and even further optionally from 20° to 26°. These angular ranges have been found to be advantageous in that they allow most broken flappers to be reliably erected. This applies particularly for the tip portion and/or the rearrangement portion being formed by an oblique cut cylinder. The said angles then allow a particularly optimized engagement of a cutting edge belonging to the contact surface with the flapper.

Preferably, the second inclination angle lies in a range from 0.5 ⁰ to 9.5 ⁰ , optionally from 1° to 8°, further optionally from 2° to 7 ⁰ , and even further optionally from 3 ⁰ to 8°. These angular ranges allow a translation of the tool along the longitudinal axis to lead to a radial movement of the flapper relative to the longitudinal axis of the cylindrical guiding portion. Particularly, jamming between the contact surface and the flapper is avoided, as observed with larger angles.

Preferably, the first area transitions into the second area via a first rounded transitional area. Said rounded transition area prevents jamming and/or snagging of the flapper with the tool. Particularly as edges on the contact surface are avoided.

Preferably, the first transitional area has a radius of curvature that lies in a range from 80 mm to 160 mm, optionally from too mm to 140 mm, and further optionally from 110 mm to 130 mm. These value ranges have proven to be advantageous in that, on the one handjamming and/or snagging is prevented, and, on the other hand, no transition area is formed that is so large that the first and/or second area are hindered in their function, as described above.

Preferably, the contact surface further comprises a third area spaced apart from the tip portion along the longitudinal axis such that the second area is arranged between the first area and the third area, wherein a third inclination angle between the third area and the longitudinal axis is larger than the second inclination angle. When determining the third inclination angle, preferably the acute angle is determined. The third inclination angle being larger than the second inclination angle has proven to facilitate and/ or accelerate finally urging the flapper into the pocket. The third inclination angle may be larger than the second inclination angle because by the time the flapper contacts the third area, the flapper is already substantially erected, and jamming and/ or snagging is less likely to occur.

Preferably, the third inclination angle lies in a range from io° to 25 ⁰ , optionally from 11° to 20°, further optionally from 12° to 18°, and even further optionally from 13 ⁰ to 16°. These ranges have proven to be particularly advantageous to urge the erected flapper into the pocket.

Preferably, the second area transitions into the third area via a second rounded transitional area. Said rounded transition area prevents jamming and/or snagging of the flapper with the tool. Particularly as edges on the contact surface are avoided.

Preferably, the second transitional area has a radius of curvature that lies in a range from 110 mm to 190 mm, optionally from 130 mm to 170 mm, and further optionally from 14 mm to 16 mm. These value ranges have proven to be advantageous in that, on the one hand jamming and/or snagging is prevented, and, on the other hand, no transition area is formed that is so large that the second and/ or third area are hindered in their function.

Preferably, the tool further comprises a motor which is configured to rotate the rearrangement portion around to the longitudinal axis. This motor is preferably an electric motor. Said motor allows the rearrangement portion and/or the tip portion to be positioned prior to contacting the flapper so that the flapper is pushed directly into the pocket when the tool is moved against the flapper. Alternatively, the tool can be rotated after erecting the flapper so that the flapper is positioned in the pocket.

Preferably, the motor is configured to rotate the rearrangement portion relative to the guiding portion. Thus, the guiding portion is prevented from sliding against the tubing and/or the tubing retrievable subsurface safety valve. Moreover, the inertia of the guiding portion may allow the rearrangement portion to be precisely rotated relative to the flapper.

Preferably, the tool further comprises a camera, wherein the camera is arranged to face the tip portion optionally substantially along the longitudinal axis. By means of the camera, a more precise positioning of the tool can be achieved. Hence, the flapper can be positioned even more reliably in the pocket. Further, it may be detected if additional damages have occurred.

Preferably, the tool further comprises a through hole extending through the rearrangement portion substantially perpendicular to the longitudinal axis to provide visibility of the camera radially outward from the longitudinal axis. Thereby the position of the pocket inside the tubing retrievable subsurface safety valve may be detected. Moreover, this configuration allows to control if the flapper is properly stowed in the pocket. Exemplarily it can be avoided that the flapper is arranged incorrect, i.e., the other way around than it was positioned in the functioning state. Said incorrect arrangement could inhibit actuating a movable tube of the tubing retrievable subsurface safety valve as the movable tube abuts the flapper.

Preferably, at least one radially outer side of the through hole is covered by a transparent shield. This transparent shield can prevent damage and/or pollution to the camera. Said transparent shield may comprise “Perspex” material.

Preferably, the tool further comprises a recess formed into the contact surface substantially along the longitudinal axis for providing visibility of the camera to the tip portion. This allows the position of the tip portion to be precisely monitored while protecting the camera.

Preferably, the recess and the through hole define a common volume in which the camera is arranged. Thus, the camera may monitor the surrounding of the tool in the direction of the tip portion, i.e., along the longitudinal axis, and perpendicular to the longitudinal axis.

Preferably, the camera is a movable camera, a fisheye camera, and/ or a wide-angle camera. These cameras have proven to be beneficial in that they provide a sufficient overview of the tool's environment and particularly of the actual location of the broken flapper prior to and during use of the tool.

Preferably, the guiding portion and/or the rearrangement portion comprise carbon steel, wherein said carbon steel optionally is alloyed with chrome, wherein further optionally at least io wt% of the carbon steel are chrome. These materials allow to meet the high mechanical and/or corrosive requirements. For example, it is possible to avoid damage of the tool by the flapper on the one hand and to prevent corrosion by hydrogen sulphide on the other hand.

Preferably, the first radius of the guiding portion defines the maximum diameter of the tool and optionally lies in a range from 50 mm to 150 mm, further optionally from 60 mm to 120 mm, and even further optionally from 70 mm to 100 mm. By the first radius of the guiding portion defining the maximum diameter of the tool it may be avoided that other portions of the tool such as the tip portion and/or the rearrangement portion accidentally contact the tubing and/or the tubing retrievable subsurface safety valve. Moreover, said ranges allow the tool to be used in most commercially used tubing.

Preferably, the tool has a length which lies in a range from 0.3 m to 2 m, optionally from 0.35 m to 1.4 m, further optionally from 0.4 m to 1.2 m, and even further optionally from 0.5 m to 1.1 m. These tool lengths allow the contact surface to be provided with suitable length and/or inclination. For example, shorter tool lengths can lead to the need to select larger angles for the contact surface relative to the longitudinal axis, which can promote jamming.

Preferably, a ratio of the first radius to the second radius lies in a range from 0.4 to 1, optionally from 0.5 to 0.99, further optionally from 0.7 to 0.98, and even further optionally from 0.9 to 0.96. These areas have proven to be advantageous in that a reliable erection of the flapper can take place.

Further, the above-mentioned object is achieved by a method for rearranging a broken flapper inside a tubing retrievable subsurface safety valve. Since the method and the above-described tool both relate to rearranging a broken flapper inside a tubing retrievable subsurface safety valve, it is understood that the features and/ or advantages described regarding the tool may apply for the method and vice versa.

The method comprises the following steps in the given order: (a) providing a flapper rearrangement tool, preferably as described above; (b) inserting the tool into a borehole comprising the tubing retrievable subsurface safety valve with the broken flapper, and (c) moving the tool against the broken flapper thereby erecting the broken flapper and after erecting pushing the broken flapper into a pocket of the tubing retrievable subsurface safety valve.

Preferably, the method further comprises the step (d) of actuating a movable tube of the tubing retrievable subsurface safety valve to keep the broken flapper within the pocket, wherein this step is performed after moving the tool against the broken flapper. The movable tube may be actuated as described in the prior art section with regards to Figs. 9a and 9b.

Preferably, the method further comprises the last step (e) of permanently fixing the movable tube in the downward position to keep the broken flapper within the pocket. For example, the movable tube may be pressed in locally from the inside so that an undercut is formed that holds the movable tube in position.

Preferably, after performing the described method steps, a replacement barrier can be installed. Exemplarily a wireline retrievable subsurface safety valve may be installed.

4. Brief description of the accompanying figures

In the following, the accompanying figures are briefly described:

Fig. 1 shows a flapper rearrangement tool according to a first embodiment of the present invention contacting a broken flapper;

Fig. 2 shows the flapper rearrangement tool of Fig. 1 in a side view;

Fig. 3 shows the flapper rearrangement tool of Fig. 1 in a side view, where the viewing plane is rotated 90 degrees compared to Fig. 2;

Fig. 4 shows the a flapper rearrangement tool of. Fig. 1 in a perspective view;

Fig. 5 shows, a flapper rearrangement tool according a second embodiment of the present invention in a perspective view;

Fig. 6 shows a technical drawing of the flapper rearrangement tool of Fig. 5 in a side view;

Fig. 7 shows a technical drawing of the flapper rearrangement tool of Fig. 5 in a side view, where the viewing plane is rotated 90 degrees compared to Fig. 6;

Figs. 8a-c show a method according to an embodiment of the present invention;

Figs. 9a, 9b show a schematic prior art tubing retrievable subsurface safety valve; and Fig. io shows a flow chart of a method according to an embodiment of the present invention.

5. Detailed description of the figures

Figs. 1, 2, 3, and 4 show a flapper rearrangement tool 1 according to a first embodiment of the present invention. Moreover in Figs. 8a-8c the tool 1 of the first embodiment is also depicted and utilized to perform a method 100 according to the present invention.

The tool 1 comprises a cylindrical guiding portion 10 having a first radius ri and a longitudinal axis a (s. Fig. 3). The first radius ri of the guiding portion defines the maximum diameter of the tool and optionally lies in a range from 50 mm to 150 mm, further optionally from 60 mm to 120 mm, and even further optionally from 70 mm to 100 mm.

Preferably, the tool 1 has a length which lies in a range from 0.3 m to 2 m, optionally from 0.35 m to 1.4 m, further optionally from 0.4 m to 1.2 m, and even further optionally from 0.5 m to 1.1 m.

As shown in Fig. 8c, the guiding portion 10 is shaped to align the tool 1 in a tubing such that the tool 1 can substantially only perform a translation along the longitudinal axis a and a rotation around the longitudinal axis a.

Further, the tool 1 comprises a tip portion 20 at a first end of the tool 1. As shown in Fig. 1, the tip portion 20 establishes initial contact with a broken flapper 5. Said tip portion 20 is radially displaced outwards relatively to the longitudinal axis a by a second radius r2. Preferably, a ratio of the first radius ri to the second radius r2 lies in a range from 0.4 to 1, optionally from 0.5 to 0.99, further optionally from 0.7 to 0.98, and even further optionally from 0.9 to 0.96.

Moreover, the tool 1 comprises a rearrangement portion 30 being arranged between the tip portion 20 and the guiding portion 10 and provides a contact surface 40. As shown, the tip portion 20 and the rearrangement portion 30 are integrally formed, namely by an oblique cut cylinder.

The contact surface 40 comprises a first area 41 adjacent to the tip portion 20, and a second area 42 spaced apart from the tip portion 20 along the longitudinal axis a such that the first area 41 is arranged between the second area 42 and the tip portion 20. Thereby a first inclination angle a between the first area 41 and the longitudinal axis a is larger than a second inclination angle P between the second area 42 and the longitudinal axis a. Preferably, the first inclination angle a lies in a range from 15 ⁰ to 35 ⁰ , optionally from 17 ⁰ to 30°, further optionally from 18° to 28°, and even further optionally from 20° to 26°. Preferably, the second inclination angle lies in a range from 0.5 ⁰ to 9.5 ⁰ , optionally from 1° to 8°, further optionally from 2° to 7 ⁰ , and even further optionally from 3 ⁰ to 8°.

The contact surface 40 further comprises a third area 44 spaced apart from the tip portion 20 along the longitudinal axis a such that the second area 42 is arranged between the first area 41 and the third area 44, wherein a third inclination angle y between the third area 44 and the longitudinal axis a is larger than the second inclination angle p. Preferably, the third inclination angle y lies in a range from io° to 25 ⁰ , optionally from 11° to 20°, further optionally from 12° to 18°, and even further optionally from 13 ⁰ to 16°.

The first area 41 transitions into the second area 42 via a first rounded transitional area 43. Preferably, the first transitional area 43 has a radius of curvature that lies in a range from 80 mm to 160 mm, optionally from too mm to 140 mm, and further optionally from 110 mm to 130 mm.

The second area 42 transitions into the third area 44 via a second rounded transitional area 45. Preferably, the second transitional area 45 has a radius of curvature that lies in a range from 110 mm to 190 mm, optionally from 130 mm to 170 mm, and further optionally from 14 mm to 16 mm.

The tool 1 further comprises a motor (not explicitly shown) which is configured to rotate the rearrangement portion 30 around to the longitudinal axis a and relative to the guiding portion 10.

The tool 1 further comprises a fisheye camera 60 being arranged to face the tip portion 20 along the longitudinal axis a. Particularly, the tool 1 further comprises a through hole 31 extending through the rearrangement portion 30 substantially perpendicular to the longitudinal axis a in which the camera 60 is arranged. As in Fig. 1, one radially outer side of the through hole 31 is covered by a transparent shield 32. Moreover, the tool 1 further comprises a recess 46 formed into the contact surface 40 substantially along the longitudinal axis a, wherein the recess 46 and the through hole 31 define a common volume in which the camera 60 is arranged. Figs. 5, 6, and 7 show a flapper rearrangement tool 2 according to a second embodiment of the present invention. The tool 2 of the second embodiment is simpler in construction and primarily differs from the tool 1 of the first embodiment in the fact that it has no camera and no respective recess and no through hole. Apart from that the other features described with respect to tool 1 of the first embodiment do also apply for tool 2 of the second embodiment.

Tool 2 is easier to manufacture, very robust, but - without sight of the operator - does not allow for a precise positioning of the tool 2 with respect to the flapper 5 during use. Instead, the flapper 5 must first be erected by moving the tool 2 in the longitudinal direction, if necessary, by hitting the flapper 5 several times and rotating the tool 2 by the wireline and/ or slickline. Then the flapper 5 can be inserted into the pocket by rotating the tool 2. However, with the tool 2 of the second embodiment it is not possible to visually determine whether the flapper is correctly positioned within the pocket. Exemplarily, if the flapper is arranged incorrect, i.e., 180° rotated to the functioning state, the movable tube of the tubing retrievable subsurface safety valve may not be able to move down to hold the flapper 5 in position within the pocket.

As shown in Figs. 6 and 7 the second flapper rearrangement tool 2 comprises fastening means 50 in the form of a thread 50 for fastening the tool to wireline and/or a slickline.

Figs. 8a-8c and 10 illustrate a method too for rearranging a broken flapper 5 inside a tubing retrievable subsurface safety valve 80 according to the present invention. The method too comprises the first step 110 of providing 110 a flapper rearrangement tool 1, 2 preferably as described above. This tool 1, 2 is then inserted by step 120 into a borehole comprising the tubing retrievable subsurface safety valve 80 with the broken flapper 5. It is understood that the tool 1, 2 maybe also inserted into a tubing comprised by the borehole. Subsequently, the tool 1, 2 is moved in step 130 against the broken flapper 5 which is thereby erected and thereafter pushed into a pocket 84 of the tubing retrievable subsurface safety valve 80.

As in Fig. 9, the method too may further comprise the step 140 of actuating a movable tube 83 of the tubing retrievable subsurface safety valve 80 to keep the broken flapper 5 within the pocket 84. With regards to Figs. 8a-c this step 140 would be performed after the flapper 5 has been pushed into the pocket 84, as shown in Fig. 8c.

Finally, in the last step 150 the movable tube 83 can be permanently fixed or locked in the downward position to keep the broken flapper 5 within the pocket 84. This ensures that the broken flapper 5 is held within the pocket 84 in any further cases, even if the hydraulic actuation of the TR-SSSVs movable tube 83 fails.

List of reference signs

1; 2 flapper rearrangement tool

5 broken flapper

10 cylindrical guiding portion

20 tip portion

30 rearrangement portion

31 through hole

32 transparent shield

40 contact surface

41 first area

42 second area

43 first rounded transitional area

44 third area

45 second rounded transitional area

46 recess

50 fastening means

60 camera a longitudinal axis ri first radius r2 second radius a first inclination angle

P second inclination angle y third inclination angle

80 tubing retrievable subsurface safety valve

81 hydraulic control line

82 reservoir

83 movable tube

84 pocket

85 functioning flapper

86 spring element too method for rearranging a broken flapper 110 providing a flapper rearrangement tool 120 inserting the tool into a borehole

130 moving the tool against the broken flapper 140 actuating a movable tube

150 permanently fixing the movable tube