TEMPERATURE ACTIVATED ZONAL ISOLATION PACKER DEVICE

Abstract

The present invention relates to a packer device (1) for sealing against an inner surface of a surrounding pipe or casing string (4), preferably for isolating zones or sections in an oil well, comprising a tubing body (3) and at least one sealing element (7a, b), where a cylinder/piston arrangement (2) comprises a cylinder (5) having a closed volume containing a fluid, such as a gas or liquid, arranged to expand when exposed to heat thereby exerting a mechanically pressure on movable elements (12), initially locked in a fixed position by means of at least one fixing element, such as a shear member (6), and where the movable elements (12) are adapted to be released into an operative state at a predetermined axial force, exerted by the closed volume in the cylinder (5), resulting in that the at least one sealing element (7a, b) is pressed radially outwardly in such a way that it seals the packer device (1) against the surrounding pipe-/casing string (4). The invention is achieved by that an endcap (13) is arranged to cover an internal piston (11) and minimize the area of the internal piston (11) that is exposed to the surrounding pressure in the well (PW) acting against the fluid pressure (P1) inside the cylinder (5). The invention also relates to a method for activating a packer device (1) to seal against the surface of a surrounding pipe or casing string (4) and the invention further relates to the use of such a packer device (1).

Claims

1. A packer device for sealing against an inner surface of a surrounding pipe or casing string, for isolating zones or sections in an oil well, comprising: a tubing body, at least one sealing element, a cylinder/piston arrangement comprising a cylinder having a closed volume containing a fluid, arranged to expand when exposed to heat, thereby exerting a mechanically pressure on-movable elements, initially locked in a fixed position by at least one shear member (6), wherein the movable elements are adapted to be released into an operative state at a predetermined axial force, exerted by the closed volume in the cylinder, resulting in that the at least one sealing element is pressed radially outwardly in such a way that it seals the packer device against the surrounding pipe-/casing string, and an endcap arranged to cover an internal piston and minimize the area of the internal piston that is exposed to the surrounding pressure in the well acting against the gas pressure inside the cylinder.

2. The packer device according to claim 1, wherein the closed volume is defined by the cylinder and the internal piston.

3. The packer device according to claim 1, wherein the cylinder/piston arrangement is ring or collar formed and arranged on the outside and around the tubing body.

4. The packer device according to claim 1, wherein the internal piston is arranged inside the cylinder.

5. The packer device according to claim 1, wherein the fluid is Nitrogen gas.

6. The packer device according to claim 1, wherein said shear member is adapted to shear when an axial force, exerted by the expanding fluid in the closed volume, generating a pressure, reaches a predetermined level that exceeds the total shear value of all the installed shear members.

7. The packer device according to claim 1, wherein a number of the shear members are arranged symmetrically around the body of the packer device.

8. The packer device according to claim 1, wherein said at least one shear member is a shear screw.

9. The packer device according to claim 1, wherein the at least one shear member (6) is made of metal.

10. The packer device according to claim 1, wherein the at least one shear member is made of steel.

11. The packer device according to claim 1, wherein the at least one sealing element is ring formed and located around the tubing body.

12. The packer device according to claim 1, wherein the at least one sealing element is at least partly conical shaped, at its inner side, in order to permit a matching movable element to be pressed into the at least one sealing element in order to displace it radially outwardly.

13. The packer device according to claim 1, wherein a fixed end stop is arranged on the outer side of each sealing element.

14. The packer device according to claim 1, wherein two of the at least one sealing elements are arranged and used in the packer device.

15. The packer device according to claim 1, wherein the at least one sealing element is made of a flexiblelresilient material.

16. The packer device according to claim 1, wherein the at least one sealing element is made of one of elastomeric, thermoplastic or a graphite composite material, or a combination thereof.

17. The packer device according to claim 1, wherein two flexible gauge rings are arranged as an centralizer/extrusion barrier in the end parts of the packer device and adapted to keep the packer device centralized in the casing string.

18. The packer device according to claim 17, wherein the flexible gauge rings are arranged as extrusion barriers preventing the sealing elements to extrude through the gap between the casing string and the packer device.

19. The packer device according to claim 17, wherein each flexible gauge ring is arranged as two circular parts connected to each other in part of their circumference by a bridge.

20. The packer device according to claim 17, wherein each circular parts having a cutaway in order to make the circular parts flexible in diameter and possible to adapt to variations in the surrounding casing.

21. The packer device according to claim 17, wherein the flexible gauge rings are made of a metal with resilient/spring properties.

22. A method for activating a packer device for sealing against an inner surface of a surrounding pipe or casing string for isolating zones or sections in an oil well, comprising a tubing body and at least one sealing element, where a cylinder/piston arrangement comprises a cylinder having a closed volume containing a fluid, such as a gas or liquid arranged to expand when exposed to heat, thereby exerting a mechanically pressure on a movable element, initially locked in a fixed position by at least one a shear member, and where the movable element is adapted to be released into an operative state at a predetermined axial force, exerted by the closed volume, resulting in that the sealing element is pressed radially outwardly in such a way that it seals the packer device against the surrounding pipe-/casing, the method comprising: reducing the effect of, or force from, the surrounding pressure in the well on the internal piston by enclosing the internal piston by an end cap thereby minimizing the area of the internal piston that is exposed to the surrounding pressure in the well acting against the gas pressure inside the cylinder.

23. (canceled)

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The invention is described in more detail with reference to non-limiting exemplifying embodiments and with reference to the accompanying drawings, in which

[0032] FIG. 1 is a partly sectioned view, of a packer device, indicated located in a well bore with a casing, according to a first embodiment of the present invention.

[0033] FIG. 2 is a sectioned side view of the packer device in an inactivated run in hole (RIH) position.

[0034] FIG. 3 is a sectioned side view, as in FIG. 2, of the packer device but in an activated (SET) and expanded position,

[0035] FIG. 4 is a more detailed side view of the packer device, in its inactivated (RIH) position.

[0036] FIG. 5 illustrates one flexible gauge ring 14a,b more in detail.

[0037] FIG. 6 illustrates the entire packer device 1 including the two flexible gauge rings 14a, b located near the ends of the packer device 1.

[0038] FIG. 7 is a partial side view of the packer device illustrating one of the sealing elements and the outer conical formed part of the cylinder as well as the locking system and a flexible gauge ring.

[0039] FIG. 8 is a partial side view of the packer device illustrating the other sealing element, the internal and external pistons.

[0040] FIG. 9 is an enlarged sectioned side view of the locking mechanism which keeps the sealing element expanded once activated.

[0041] FIG. 10 is a perspective view of one part of the locking mechanism, the splitted locking ring.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

[0042] FIGS. 1 through 8 illustrates different parts/embodiments of the present invention, a temperature activated, zonal isolation packer device for use in a well bore with a casing string, preferably in high-temperature applications, for isolating zones in the well. It is emphasized that the invention is in no way restricted to a packer device for a specific use, but it can be applied to any application where sealing have to be done, as long as the object of the invention is obtained.

[0043] FIG. 1 is a perspective view, partially sectioned, of the present invention, the temperature activated zonal isolation packer device.

[0044] The packer device 1 according to the invention comprises of a few main components: [0045] a closed but expandable volume, such as a ring or collar formed cylinder/piston arrangement 2, positioned on a part of a tubing 3 located in a casing 4 and including an “cylinder” 5, filled with a fluid, such as Nitrogen gas, at a predetermined pressure, which pressure is calculated and depending on the surrounding conditions in the well, such as its temperature and pressure, [0046] “shear members” 6 that keeps the sliding parts of the packer device 1 in place at normal temperatures, but that shears when a predetermined force, from the heated and expanding fluid in the cylinder 5, is reached, [0047] one or more “sealing elements” 7a,b that expands and are pushed/pressed outwards radially towards the casing 4 creating a barrier or seal between the packer device 1, tubing body 3 and the casing 4, by a cylinder/piston arrangement 2, as a result of the force that the expanding fluid in the packer device 1 creates, [0048] a “locking system” 8 that keeps the movable parts of the packer 1 in place after the expansion, in the “set” position. [0049] Flexible gauge rings 14a,b, FGR, forms a “centralizer and/or extrusion barrier”, arranged at the ends of the packer device 1 to keep it centralized in the casing 4. The flexible gauge rings 14a,b also works as extrusion barriers for the expanded sealing elements.

[0050] The tubing body 3 has the form of a pipe having a first end and a second end provided with threads 9a,b by which the packer device 1 could be connected to the overall tubing system (not illustrated) in the well.

[0051] The choice of material of the packer device 1 may depend on the mechanical and chemical environment in the actual application, but its parts are generally made of steel.

[0052] FIGS. 2 and 3 are sectioned side views of the packer device 1. In the figures the tubing body 3 of the packer device 1 is illustrated in its entire length. In FIG. 2 the packer device 1 is in an inactivated (RIH) position and in FIG. 3 the packer device 1 is in an activated and expanded (SET) position, where the sealing elements 7a,b are pressed against the inner wall of the casing 4. The packer device 1 forms a part of the overall tubing in the well and is in these figures located inside the casing string 4. The longitudinal and slide-able arranged cylinder 5 forms a closed expandable volume containing a fluid, such as Nitrogen gas. The fluid could be filled into the cylinder 5 at surface through filling plugs 10 before the packer device 1 is run into the well. The cylinder is connected to or integrated with at least one movable element such as an internal piston 11 and/or an external piston 12. The internal piston 11 is axially slide-able arranged inside the cylinder 5 and pushes against the partly conically formed external piston 12. A number of O-rings seal the movable parts to each other and to the body of the packer device 1.

[0053] The cylinder 5 and pistons 11,12 are adapted to move axially relative to each other but are held together in axial direction by shear members 6 adapted to shear when an pre-defined axial force due to the increased pressure in the cylinder 5 exceeds the total shear value of the shear members 6. When the fluid inside the cylinder 5 is exposed to the surrounding heat from e.g. hot steam injected into the well through the tubing 3, the fluid pressure within the cylinder 5 increases. At a certain force generated by the fluid pressure, the shear member 6 shears and the cylinder 5 and pistons 11,12 slides, in opposite directions from each other, thereby pressing the conically formed external piston 12 and the conically formed outer end of the cylinder 5 against, and at least partly in under the sealing elements 7a,b. The sealing elements 7a,b are pushed outwardly, from the packer device body, toward the wall of the surrounding casing 4 and seal thereby effectively the annulus between the tubing 3 and casing 4. The sealing elements 7a,b may be made of any resilient elastomeric or thermoplastic material or similar materials. In high temperatures or aggressive chemical environments, different types of thermoplastic combinations can be used in the sealing elements 7a,b.

[0054] The locking system 8 locks the cylinder 5 and/or the external piston 12 in their axially expanded positions and keeps firmly thereby the sealing elements 7a,b in their outwardly activated/expanded positions, even if/when the surrounding temperature of the packer device 1 is lowered, for example if the steam injecting phase comes to an end.

[0055] The number of shear members 6 and the material of the shear members 6 are adapted and calibrated to shear at a pre-defined force depending on the desired shear force value in order to give the required shearing conditions. The number of members 6 is based on a combination of the filling pressure of the fluid, the nitrogen gas, and the available force caused by the increased temperature and the air-pressure in the well. A preferred material of the shear members 6 is brass since brass has good shearing qualities. Other possible materials can be different types of steel, for example low strength or high strength steel.

[0056] FIG. 4 is for reference a more enlarged and detailed sectioned side view of the packer device 1, here illustrated in its inactivated (RIH) position. The cylinder/piston arrangement 2 comprises of four main components, the cylinder 5 itself, one end cap 13, one internal piston 11 and one external piston 12. The cylinder 5 forms the closed volume for the fluid, the gas, that when expanding acts on the internal piston 11. The end cap 13 covers/protects the internal piston 11 and the area of the internal piston 11 exposed to the well pressure is thereby minimized. This minimizes the negative effect of the well pressure acting against the fluid pressure inside the cylinder 5, resulting in a higher force acting on the internal piston 11 and external piston 12 and in the end on the sealing elements 7a,b.

[0057] The function of the internal piston 11 is thus to reduce the effect of the well pressure PW that will always be present in the well. The force F acting on the external piston 12 (and the sealing element 7a) is the sum of the forces F1 and F2 (where F2 is negative). F1 is the force generated by the pressure acting on a larger area A1 of the internal piston 11 and F2 is the force generated by the well pressure PW acting on a smaller area A2 of the internal piston 11. The important effect is that the area A2, on which the well pressure PW is acting, is minimized. The shear members 6 are dimensioned to hold for F1 (plus a safety margin) at atmospheric pressure PA, but will shear at elevated temperature that effects the packer device 1 in the well, due to the increased pressure P1 in the cylinder 5 giving a higher force F1.

[0058] Flexible gauge rings 14a,b (FGR) are used at the ends of the packer device 1 to keep it centralized in the casing 4, especially in more or less horizontal wells/casings 4.

[0059] FIG. 5 illustrates one flexible gauge ring 14a,b more in detail. The flexible gauge ring 14a,b comprises of two ring or circular formed parts 17a,b, each formed with a cutaway 18a,b in one location, which makes each circular part 17a,b flexible or compressible, i.e. the part 17a,b, and therefore the flexible gauge rings 14a,b diameter may vary which makes them possible to adapt to variations in the surrounding casing 4. The two parts 17a,b, are connected to each other at one part of their circumference, by a bridge 19. The flexible gauge rings 14a,b are kept centralized in the packer device 1 by two edges 20a,b (see FIG. 7) formed in the stop elements 15a,b at the end of the packer device 1.

[0060] A flange 20a,b on the outer side of each circular part 17a,b is arranged to interact with the corresponding flange 21a,b in the stop elements 15a,b in order to keep the flexible gauge rings 14a,b into the packer device 1 and in order for them to be able to centralize the packer device 1 in the casing 4.

[0061] The flexible gauge rings 14a,b are arranged with a somewhat larger outer diameter than the inner diameter of the casing 4 and the intention is that the flexible gauge rings 14a,b always should stay in contact with the casing 4 even if its diameter may vary.

[0062] The flexible gauge rings 14a,b should be dimensioned to keep the packer device 1 in the center of the casing 4 but at the same time not to execute a too large force radially outwards, against the casing 4.

[0063] The advantage of having the packer device 1 centralized in the casing 4 is that the force generated by the cylinder/piston arrangement 2 does not have to be used to lift the packer device 1, especially when located in a horizontal casing 4. This means that maximum force will be used for expanding the sealing elements 7a,b out to the casing, and the packer device 1 will function as intended.

[0064] The flexible gauge rings 14a,b also, at the same time, are arranged and works as extrusion barriers, preventing the sealing elements 7a,b, made of a flexible material, to extrude through the gap between the casing 4 and the packer device 1 which otherwise may happen at high temperatures and pressures.

[0065] FIG. 6 illustrates the entire packer device 1 including the two flexible gauge rings 14a,b located near the ends of the packer device 1. The flexible gauge rings 14a,b keeps the packer device 1 both balanced and centralized in the casing 4, even if the packer device 1 is located in a horizontal casing 4.

[0066] FIG. 7 is a partial side view of the packer device 1 illustrating one of the sealing elements 7a and the outer conical formed part of the cylinder 5 as well as the locking system 8 and a flexible gauge ring 14a. The sealing element 7a is designed with a conically formed end directed against the cylinder 5, which in turn has a conically formed outer end. This outer end of the cylinder 5 also forms part of the locking system 8 that includes a lock ring 16. On the opposite side of the sealing element 7a is a fixed stop element 15a arranged to the body 3 of the packer device 1, preventing the sealing element 7a to slide axially when the cylinder 5 is moving against the sealing element 7a exerting a mechanical force on it. The stop element 15a,b is here also used as a gauge ring body, keeping the flexible gauge ring 14a,b in place. The outer surface of the each of the two parts 17a, b of the flexible gauge rings 14a, b are formed somewhat convex in order to make it possible to install the packer device more easily in the casing 4. The angle of each such surface is arranged with a relatively small angle α in relation to the inner surface of the casing 4 and this result in that the packer device 1 may be installed into the casing 4 with a relatively small axial force.

[0067] FIG. 8 is a partial side view of the packer device 1 illustrating more in detail the other sealing element 7b and the internal piston 11 and external piston 12 as well as the shear members 6. The shear members 6 keeps the end cap 13 and the external piston 12 fixed to each other in the packer devices 1 inactivated position. On the opposite side of the sealing element 7b is another stop element 15b fixed to the body 3 of the packer device 1.

[0068] FIG. 9 is an enlarged sectioned side view of the locking system 8 which keeps the sealing element 7a expanded once activated. The locking system 8 consists of three elements, a splitted lock ring 16 with both internal and external threads, a fine external thread on the tubing body 3, and a larger internal thread on the cylinder 5 and the external piston 12 (not illustrated here). The lock ring 16 is splitted to allow for it to partly expand outwardly. The lock ring 16 can move axially one way with the cylinder 5 and/or the external piston 12, but is restricted to move back by the thread on the tubing body 3.

[0069] When the cylinder 5 and/or piston 12 move axially, the lock ring 16 is pushed in the same direction through mechanical contact with the external thread towards the corresponding thread in the cylinder 5 and/or piston 12. Since the lock ring 16 is splitted, it can expand, and “jump” over the threads of the tubing body 3. The internal thread of the cylinder 5 and/or piston 12 is made deep to allow for the expansion of the lock ring 16, but in such a way that it still maintain contact with the external thread of the lock ring 16 in its locked and “closed” position.

[0070] When the cylinder 5 and/or piston 12 are in the SET position, the spring-back from the expanded sealing element 7a,b will try to force the cylinder 5 and/or piston 12 back to their original positions. The lock ring 16 will now be pressed inwards, towards the body 3, by the internal threads in the cylinder 5 and piston 12. This will force the vertical part of the internal thread to engage with the corresponding thread of the tubing body 3 and this will lock the lock ring 16 in its position and of course also the cylinder 5 piston 12 from moving in relation to the tubing body 3 and prevent them from moving back.

[0071] FIG. 10 is a perspective view of the splitted lock ring 16 with its internal and external threads. The lock ring 16 is preferably manufactured of a material having a spring characteristic. According to one preferred embodiment, the lock ring 16 is made of steel.

[0072] The above description is primarily intended to facilitate the understanding of the invention. The invention is of course not limited to the above embodiments but also other variants of the invention are possible and conceivable within the scope of the invention and the appended claims. The invention is of course possible to use in other applications not mentioned here and the fluid used in the cylinder 5 could be any form of gas or liquid. It is also possible to use only one sealing element 7a/b. In that case only one of the cylinder 5 or the external piston 12 may be movable. The packer device 1 can of course also be used for other purposes and in other areas of use than those described above, such as thermal water wells or for sealing applications in pipes in general.