Technical Field

The invention relates to a seal sleeve having a seal sleeve wall that includes swellable polymer material, to an assembly including such a seal sleeve and to a method for applying a seal sleeve between an inner element and an outer element.

Background

A swellable seal sleeve is known from e.g. WO03/008756, WO06/003113 and US2007/0056735. In all these publications the seal sleeves disclosed therein are annular objects with a radial wall thickness in a non- swollen state and an increased radial wall thickness in a swollen state.

In all the publications, the sealing effect is obtained by virtue of the fact that the radial wall thickness of the annular object increases due to the swelling. Suppose that the annular space that has to be closed off has a radial width of X and the material of which the seal sleeve is made has a swelling ratio of 2, then the minimum wall thickness of the annular seal sleeve according to the prior in a non-swollen state has to be X/2. Especially when the annular space that has to be sealed has a considerable radial width, the wall thickness of the annular seal sleeves of the prior art is also considerable. As a consequence, the prior art seal sleeves can only be used in annular spaces that have a limited width.

WO2005/088064 discloses a sleeve that may be of swellable material and that is configured to be mounted on a expandable tubular section of the tubing. Expandable tubing is of reduced diameter during installation. After expansion, the internal diameter of the tubing is increased thus improving the flow of fluids through the tubing. In figures 6-7 of the publication, a sleeve is disclosed that is connect at one end to a fixed ring on the tubing. The fixed ring holds the sleeve in place. A sliding ring is connected to the other and of the sleeve. The sleeve is notched or grooved to generate hinge or flexing sections. When the tubing is run into the borehole, the sleeve has a substantial cylindrical shape. Subsequently, an expansion tool is inserted into the tubing to radially expand the tubing. When moving the expansion tool through the tubing, the expansion front of the tubing that moves forward along the tubing pushes the sliding ring of the sleeve towards the fixed ring of the sleeve.

Thereby, the sleeve is folded into an accordion shape. In the folded condition, the sleeve 88 has an increased radial dimension, i.e. it extends substantially farther from the outer surface of the tubing than it did as installed for running in. The known sleeve is only fit to be used in expandable tubing because the accordion shape is obtained by virtue of the fact that the tubing is subjected to an expansion operation.

Summary of the Invention

The invention is directed to a seal sleeve that alleviates the problems of the prior art and that is fit to be applied on inner element that is not expandable, for example a non-expandable wellbore production tubular or a wellbore casing.

More particularly, the invention is directed to a seal sleeve with which an annular space between an inner element and an outer element can be closed off that has a considerable radial width.

To that end the invention provides a seal sleeve suitable to be mounted on an inner element, more particular on a non-expandable inner element, for example a wellbore production tubular or a wellbore casing, the seal sleeve having a seal sleeve wall comprising a swellable polymer material having elastomeric properties so that the seal sleeve has non-swollen state and an expanded state:

• the seal sleeve wall having a closed circumference that extends around a central longitudinal axis and that has a certain length in the direction of the central axis that extends in a longitudinal direction; • the seal sleeve wall having a non-swollen thickness that is defined by the distance between an inner surface and an outer surface of the seal sleeve wall in the non-swollen state and having a expanded thickness that is defined by the distance between the inner surface and the outer surface of the seal sleeve wall in the expanded state;

characterized in that the seal sleeve wall, before and after being mounted on an inner element includes:

• a first longitudinal wall part that extends, when viewed in the longitudinal direction, radially outwardly; and

• a second longitudinal wall part that extends, when viewed in the longitudinal direction, radially inwardly.

Such a seal sleeve may be applied for use in an assembly that includes an inner element having an outer surface and an outer element having an inner surface. The inner element being receivable within the outer element so that a circumferential space is present that extends in the longitudinal direction and that has a radial width defined by the distance between the outer surface of the inner element and the inner surface of the outer element. The seal sleeve is configured to close off the circumferential space in the expanded state thereof. In the non-swollen state the seal sleeve has a radial width that is less than the radial width of the circumferential space.

Generally, the swellable polymer material swells in all directions to the same relative extent. That is, when the thickness of the seal sleeve wall in the non-swollen state is T, the thickness in the swollen state will be T.C wherein C is a constant that is larger than 1. However, the length LI of a first part or the length L2 of a second part, as seen in a radial cross sectional view along a plane that includes the longitudinal axis, is generally much greater than the seal sleeve wall thickness T, for example in the order of 3T to 8T. Thus the expansion in of the first part along its length and the second part along its length is in the order of 3T.C to 8T.C. Because the first part and the second part extend radially outwardly and radially inwardly respectively when viewed in the longitudinal direction, the expansion along the length of the first and the second part leads to an increased radial expansion of the seal sleeve. As a consequence, a circumferential space having a larger radial width between an inner and an outer element can be sealed while the seal sleeve wall thickness may be kept relatively small. Consequently, the that the amount of swellable polymer material that is necessary to close off a circumferential space having a radial width may be reduced relative to the prior art seal sleeves that are manufactured form swellable polymer material.

The first part of the seal sleeve wall, when viewed in a cross sectional radial view along a central radial plane that includes the central axis A, extends in a direction Dl that includes an angle a with the central axis A. The amount of radial expansion is dependent on the angle a and the length LI of the first part.

In an embodiment, in the non-swollen state of the seal sleeve the angle a may be in the range of 25-90 degrees, preferably in the range of 45-80 degrees.

The second part of the seal sleeve wall, when viewed in a cross sectional radial view along a central radial plan that includes the central axis A, extends in a direction D2 that includes an angle 6 with the central axis A. The amount of radial expansion of the seal sleeve is dependent on the angle 6 and the length L2 of the second part.

In an embodiment, in the non-swollen state of the seal sleeve the angle 6 may be in the range 25-90 degrees, preferably in the range of 45-80 degrees.

As a consequence of the swelling, these angles a and 6 may increase up to 90 degrees. Because the first and second longitudinal wall parts also swell in thickness, the situation in the swollen state of the seal sleeve may be that the inner surfaces of the first and the second wall parts that are directed towards each other in the non-swollen state are abutting against each other in the swollen state of the seal sleeve. Thus a very strong structure will be obtained that has sufficient structural strength to withstand a large pressure difference between opposite sides of the seal sleeve.

An even better strength and thus better ability to withstand a pressure difference between opposite sides of the seal sleeve may be obtained with an embodiment that includes a plurality of said first parts and a plurality of said second parts, wherein, viewed in the longitudinal direction D, first parts and second parts are alternately consecutively provided. In effect, this creates a seal with a plurality of sealing dams.

In an embodiment, such a strong seal sleeve may have a bellow shaped seal sleeve wall. The bellow shape provides a plurality of sealing dams when the seal sleeve is in the expanded state thus providing an excellent seal between the opposite sides of the seal sleeve that may withstand a large pressure difference in the order of .several hundred bar.

In order to further improve the strength of the structure of the seal sleeve, in an embodiment, the seal sleeve may include a cylindrical core that is stiff. The core may be a metal core or a rubber or plastic core with a high rigidity.

In an embodiment of the seal sleeve with a cylindrical core, the seal sleeve may have a seal sleeve wall that comprises a part also extends at least partly at an inner surface of the cylindrical core. Such a construction may be advantageous for mounting the seal sleeve on an inner element, such as for example a metal pipe or tube. In the non-swollen state, the seal sleeve may be slid over the metal pipe or tube and be fixed by one or more fixation screw or other fixation means such as chemical bonding or a mechanical locking system. When the swellable material is brought into the expanded state, a

hermetically closed seal between the cylindrical core and the inner element is automatically obtained due to the expansion of the seal sleeve wall part that extends at the inner surface of the cylindrical core. The invention also provides an assembly of a seal sleeve according to the invention and an inner element having an outer surface and an outer element having an inner surface, wherein the inner element is receivable within the outer element so that a circumferential space is present that extends in a longitudinal direction D and that has a radial width W defined by the distance between the outer surface of the inner element and the inner surface of the outer element.

In an embodiment, the inner element may be a casing and the outer element may be a well bore hole wall.

In yet another embodiment, the inner element may be a production tubular and the outer element may be a casing of casing string in a well bore hole.

The invention also provides a method for applying a seal sleeve between an inner element and an outer element. The method includes:

• providing an outer element having inner surface;

• providing an inner element having an outer surface, the dimension of the inner element relative to the outer element being such that the inner element is receivable in the outer element;

• providing a seal sleeve according to the invention;

• applying the seal sleeve over the inner element;

• fixing the seal sleeve at a longitudinal position on the inner element;

• introducing the inner element into the outer element; and

providing a liquid that induces the swelling of the swellable polymer material of the seal sleeve wall.

The invention will be further elucidated with reference to some examples of embodiment that are shown in the drawings.

Brief Description of the Drawings Fig. 1 shows a front view of an example of an embodiment of an assembly including examples of two embodiments of a seal sleeve in a non- swollen state;

Fig. 2 shows a cross sectional view over line II-II in Fig. 1, i.e. along a radial plane that includes a longitudinal axis A of the two seal sleeves shown therein;

Fig. 3 shows a detail III of Fig. 2;

Fig. 4 shows a front view of an example of an embodiment of an assembly including examples of two embodiments of a seal sleeve in an expanded state;

Fig. 5 shows a cross sectional view over line V-V in Fig. 4, i.e. along a radial plane that includes a longitudinal axis A of the two seal sleeves shown therein;

Fig. 6 shows a detail VI of Fig. 5;

Fig. 7 shows a perspective view of an example of a first embodiment of the seal sleeve;

Fig. 8 shows a side view of the example of the first embodiment of the seal sleeve in the non-swollen state;

Fig. 9 shows a side view of the example of the first embodiment of the seal sleeve in the expanded state; and

Fig. 10 shows a perspective view of the example of the second embodiment of the seal sleeve.

Detailed Description

Figs. 1-3 show an example of an embodiment of an assembly that includes an inner element 100 having an outer surface and an outer element 110 having an inner surface. The inner element 100 is received within the outer element 110 so that a circumferential space 120 is present that extends in a longitudinal direction D and that has a radial width W defined by the distance between the outer surface of the inner element 100 and the inner surface of the outer element 110. Figs. 1-3 show two examples of two different embodiments of a seal sleeve 10.

The example of a first embodiment of the seal sleeve 10 is shown left in Fig. 2 and in Figs. 7 and 8 in a non-swollen state. Fig. 5 on the left and Fig. 9 show the same example of the first embodiment in an expanded state.

The example of the second embodiment of the seal sleeve 10 is shown right in Fig. 2 and in the detail shown in Fig. 3 as well as in Fig. 10 in a non-swollen state. Fig. 5 on the right and the detail of Fig. 6 show the example of the second embodiment in an expanded state.

Generally, a seal sleeve 10 according to the invention that is suitable to be mounted on an inner element, more particular on a non-expandable inner element, for example a wellbore production tubular or a wellbore casing, has a seal sleeve wall 12 comprising a swellable polymer material having

elastomeric properties so that the seal sleeve has non-swollen state and an expanded state. The seal sleeve wall 12 has a closed circumference that extends around a central longitudinal axis A and that has a certain length L in the direction of the central axis A that extends in the longitudinal direction D. The seal sleeve wall 12 has a non-swollen thickness Tn that is defined by the distance between an inner surface and an outer surface of the seal sleeve wall 12 in the non-swollen state. The seal sleeve wall 12 also has an expanded thickness Te that is defined by the distance between the inner surface and the outer surface of the seal sleeve wall 12 in the expanded state. The non-swollen thickness Tn is considerable less than the radial width W of the

circumferential space 120. The expanded thickness Te is, in general also less than the radial width W of the circumferential space W, this in contrast to the prior art sleeves. The seal sleeve 10 also defines a radial seal sleeve width Ws which is the width Ws that is defined by the difference between the smallest inner radius of the seal sleeve 10 and the largest outer radius of the seal sleeve 10. In the non-swollen state the seal sleeve width Wsn is considerably less than seal sleeve width Wse in the expanded state. When the seal sleeve 10 is applied in the assembly, i.e. expanded between the inner element 100 and the outer element 110, the seal sleeve width Wse in the expanded state in general is equal to the width W of the circumferential space 120. If no outer element 110 is present, the seal sleeve width Wse in the expande state of the seal sleeve 10 will, in general, be considerably larger than the width W of the circumferential space 120.

Before and after being mounted on an inner element, the seal sleeve wall 12 generally includes a first longitudinal wall part 14 that extends, when viewed in the longitudinal direction D, radially outwardly. The seal sleeve wall 12 additionally includes a second longitudinal wall part 16 that extends, when viewed in the longitudinal direction D, radially inwardly.

In the first embodiment there are only one first longitudinal wall part 14 and one second longitudinal wall part 16, as is clearly visible in Figs. 7-9 that shows an example of the first embodiment of the seal sleeve 10.

In the second embodiment, there is a plurality of said first parts

14a- 14e and a plurality of said second parts 14a- 14e. When viewed in the longitudinal direction D the first parts 14a- 14e and the second parts 16a- 16e are alternately consecutively provided. This is clearly visible in the cross- sectional view on page 2 and in Fig. 10. This specific example of the second embodiment has a seal sleeve wall 12 that is bellow shaped.

As shown in Fig. 2 a said first part 14, 14a- 14e of the seal sleeve wall 12, when viewed in a cross sectional radial view along a central radial plane that includes the central axis A, extends in a direction Dl that includes an angle a with the central axis A in the range of 25-90 degrees, preferably 45- 80 degrees. A said second part 16, 16a- 16e of the seal sleeve wall 12, when viewed in a cross sectional radial view along a central radial plan that includes the central axis A, extends in a direction D2 that includes an angle 6 with the central axis A in the range 25-90 degrees, preferably 45-80 degrees.

When the Dl and D2 directions include angles in such ranges with the longitudinal axis A, a seal sleeve 10 is obtained that provides a great structural strength in an expanded state so that a large pressure difference at opposite sides of the seal sleeve 10 may be withstand by the seal sleeve 10.

In an embodiment, of which examples are shown in the figures, the seal sleeve 10 may comprise a cylindrical core 18 that is stiff. In the examples that are shown in the figures, the cylindrical core 18 is provided at an inner side of the seal sleeve wall 12.

In another an embodiment of a seal sleeve 10 with a cylindrical core 18, a part 20 of the seal sleeve wall 12 may also extend at least partly at an inner surface of the cylindrical core 18. In such an embodiment, the cylindrical core 18 may be completely embedded in the seal sleeve wall 12 of swellable polymer material. Such an embodiment has the advantage of structural strength in combination with an easy mounting of the seal sleeve 10 on an inner element 100. The seal sleeve may be shifted over the inner element 100 and may be temporarily fixed by fixing means such as a fixing screw, a wedge or glue. After swelling the part of the seal sleeve wall 12 that is on the inside of the cylindrical core 18 expands against the inner element 100 and thus provides an excellent seal on that side as well.

In an embodiment of the assembly, the inner element 100 may be a production tubular and the outer element 110 may be a casing in a well bore hole. Figs. 1-6 show an example of such an embodiment of the assembly. The casing 110 extends in a bore hole in an earth layer 130.

In an another embodiment of the assembly, the inner element 100 may a casing of a casing string and the outer element 110 may be a well bore hole wall.

In yet another embodiment, the outer element 110 may a housing of an apparatus and the inner element 100 may be a shaft that is mounted in the housing.

Suitable elastomers are rubber materials which, apart from swelling in watery fluids alternatively or additionally may swell in crude oil present in petroleum wells. Alternatively or additionally rubber materials may be used that swell in contact with certain gases. Watery fluids may be neutral, alkaline or acid fluids. Examples of suitable rubber materials are ethylene propylene rubber (EPM and EPDM); ethylene- propylene-diene terpolymer rubber (EPT); butyl rubber (IIR); brominated butyl rubber (BUR); chlorinated butyl rubber (CIIR); chlorinated polyethylene (CM/CPE); neoprene rubber (CR);

epichlorohydrin ethylene oxide copolymer (CO, ECO); styrene butadiene copolymer rubber (SBR); sulphonated polyethylene (CSM); ethylene acrylate rubber (EAM/AEM); silicone rubbers (VMQ); and fluorsilicone rubber (FVMQ).

Also suitable are rubber materials which do not swell in crude oil, such as butadiene acrylonitrile copolymer (nitrile rubber, NBR); hydrogenated NBR (HNBR, HNS), such as ZETPOL™, TORNAC™, TERBAN™; NBR with reactive groups (X-NBR); perfluoro rubbers (FFKM) such as KALREZ™, CHEMRAZ™; fluoro rubbers (FKM), such as VITON™, FLUOREL™; and tetrafluorethylene/propylene (TFE/P), such as AFLAS™.

Most of these elastomers can be crosslinked by more than one crosslinking agent {e.g. either sulphur crosslinked or peroxide crosslinked).

Apart from the thermoset (non swelling and oil swelling) elastomer matrix materials quoted above, also blends of elastomers can be applied (so called "elastomeric alloys"). Although an almost inexhaustible combination of thermoplastic and thermoset elastomers are feasible, the most preferred are the EPDM/polypropylene blends such as SARLINK™, Levaflex™,

Santoprene™, NBR-polypropylene blends such as GEOLAST™,

NBR/polyvinylchloride blends and NR/polypropylene blends. All of these have a tendency to swell in petroleum crudes, especially at the targeted downhole well temperatures.

In an application of the seal sleeve 10, the following method may be used:

• providing an outer element 110 having inner surface;

• providing an inner element 100 having an outer surface, the

dimension of the inner element 100 relative to the outer element 110 being such that the inner element 100 is receivable in the outer element 110;

• providing a seal sleeve 10 according to any one of claims 1-7;

• applying the seal sleeve 10 over the inner element 100;

· fixing the seal sleeve 10 at a longitudinal position on the inner

element 100;

• introducing the inner element 100 into the outer element 110;

• providing a liquid that induces the swelling of the swellable polymer material of the seal sleeve wall 12.

With this method the seal sleeve 10 may be applied at a desired position and an adequate sealing may be obtained both at the outer

circumference of the seal sleeve 10 and the inner circumference of the seal sleeve 10. When the seal sleeve 10 is provided with a cylindrical core 18 that is rigid, the sealing at the inside of the seal sleeve 10 may be further promoted when a part of seal sleeve wall 12 of swellable polymer material also extends at least partly along an inner surface of the cylindrical core 18.

Although illustrative embodiments of the present invention have been described above, in part with reference to the accompanying drawings, it is to be understood that the invention is not limited to these embodiments. Variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. Reference throughout this specification to "one embodiment" or "an embodiment" means that a particular feature, structure or characteristic described in connection with the

embodiment is included in at least one embodiment of the present invention. Thus, the appearances of the phrases "in one embodiment" or "in an

embodiment" in various places throughout this specification are not

necessarily all referring to the same embodiment. Furthermore, it is noted that particular features, structures, or characteristics of one or more embodiments may be combined in any suitable manner to form new, not explicitly described embodiments.