AU2011205159B2 - A method and a device for expanding a body under overpressure - Google Patents

Abstract

A method and a device for expanding a body (10, 22) under overpressure, in which the body (10, 22) which is formed of a material (12, 24) with a considerable portion 5 of cavities, and which is compressed when being placed in an area of overpressure, is expanded by the cavities filling with fluid. 04/08/I, 19366 speci, 2 Fig. 1

Description

AUSTRALIA Patents Act 1990 ORIGINAL COMPLETE SPECIFICATION INVENTION TITLE: A METHOD AND A DEVICE FOR EXPANDING A BODY UNDER OVERPRESSURE The following statement is a full description of this invention, including the best method of performing it known to us: 04/08/11. 19366 covuaL svcci. I -2 A METHOD AND A DEVICE FOR EXPANDING A BODY UNDER OVERPRESSURE This invention relates to a method for expanding a body under overpressure. More 5 particularly, it concerns the expansion of a body that is made of an elastic material having a considerable portion of closed cavities, the material allowing the diffusion of a fluid through the material and into the cavities. The method is particularly suitable for operations in the ground, in which a body of this kind, when it is being lowered to the desired position, is compressed by the prevailing overpressure, after 10 which a fluid diffuses, over some time, through the material and into the cavities. Alternatively, the cavities are open and are held in compression during insertion into an area of elevated pressure. (This embodiment however is not claimed). The invention also includes a device for practicing the method. 15 Bodies of this kind may have a number of applications, for example as an annular packer in an underground well. In this description, to illustrate the operation, such an application has been taken as the starting-point. The example does not in any way limit the use of the body to this example. 20 Completing a petroleum well by means of a sand screen in an open hole is a simile and reliable method for completing a reservoir section. A petroleum well normally penetrates formations of varying production properties. These different properties may lead to undesired well fluid of an area flowing in through the sand screen and further into the production pipe. 25 It may thus be desirable to close off an area to the inflow of fluid. This closing off must take place in the annulus between the sand screen ad the well hole. According to the prior art, such closing off is effected for example by means of 30 inflatable annular packers which are placed at a desirable location, and which are then activated by means of relatively complicated equipment. It has sometimes 04/08/1 1, 19366 speci, 2 -3 turned out to be difficult to achieve pressure tightness by the use of packers of this kind. Patent No. 312478 discloses a packer which is made of a swellable material. After 5 the packer has been placed at a desired location, the material of the packer absorbs a fluid and thereby swells until it seals the annulus. In some well, for example when dry gas is produced, it can be difficult to achieve sufficient swelling of the packer material. 10 WO/02059452 discloses an expandable elastomeric material that expands when in contact with an actuating wellbore agent. The invention has as its object to remedy the drawbacks of the prior art. 15 The object is realized in accordance with the invention through the features specified in the description below and in the following Claims. By placing a body which is made of an elastic material with a considerable portion of closed cavities the material allowing the diffusion of a fluid through the material into 20 the cavities, in an area where overpressure is prevailing, the material will be compressed, in particular through reduction of the volume of the cavities and thereby that of the material. Over time a surrounding fluid diffuses through the material into the cavities, whereby 25 the body expands into its essentially original dimension, possibly until it is prevented from further expansion by adjacent bodies. Alternatively, the elastic material may be formed with many open cavities, the material being kept in compression, for example by means of a compressing 30 material, so that the cavities are at least partially compressed during insertion of the material into an area of elevated pressure. After the material has been placed in the area in question, the material is released from its compressed state, whereby fluid 04/08/1 I, 19366 spci, 3 -4 flows into the cavities of the material. The material thereby expands to its essentially original size. (This embodiment however is not claimed). Bodies of this kind are suitable for application also in water wells and dry gas wells, 5 in which swelling materials are usable only to a limited degree. In accordance with a first aspect of the present invention there is provided a method for expanding a body under elevated pressure, the method including the steps of: forming the body from an elastic material with a substantial portion of closed cavities 10 therein; placing the body in an area of elevated pressure, thereby compressing the body; and expanding the body by diffusion of fluid present at the body through the elastic material and into the cavities. In accordance with another aspect of the present invention there is provided a device 15 including: an expandable body formed of an elastic material with a substantial portion of closed cavities therein, and which is configured to be placed, in a compressed form, in an area of elevated pressure, and wherein the elastic material includes a diffusible material. 20 In accordance with yet a further aspect of the present invention there is provided a method for expanding a body under elevated pressure, the method including the steps of: forming the body from an elastic material with a substantial portion of cavities therein; placing the body in an area of elevated pressure; and expanding the body by diffusion of a fluid through the elastic material and into the cavities, the expanding 25 step further including expanding the cavities by diffusion of the fluid through the elastic material and into the cavities. In accordance with yet another aspect of the present invention there is provided a device including: a body formed of an elastic material with a substantial portion of 30 cavities therein, wherein the body is compressed and then expanded by diffusion of a fluid through the elastic material and into the cavities, and wherein pressure is 06/02/12,dh-19366 - specipg4 - jpw,4 - 4a egualized between the cavities and an area of elevated pressure by the diffusion of the fluid through the elastic material and into the cavities. In accordance with yet a further aspect of the present invention there is provided a 5 method of sealing in a well, the method including the steps of: positioning an expandable body in the well, the body including a material having cavities therein, the positioning step including applying an elevated pressure to the body; compressing the body, thereby reducing a volume of the body, as a result of the elevated pressure; and then expanding the body into sealing contact with a surface in 10 the well. In order that the invention may be more clearly understood and put into practical effect reference will now be made to preferred embodiments of a method and the device in accordance with the invention. The ensuing description is given by way of 15 non-limitative example only and is in reference to the accompanying drawings, wherein: Figure I shows a production pipe with a sand screen in an underground well, in which there are arranged annular packers according to the invention to limit the 20 admission area of the sand screen; Figure 2 shows, on a larger scale, a section of Figure 1; Figure 3 shows an expandable pipe which is provided externally which a sleeve of 25 compressed expandable material before expansion has taken place; and Figure 4 shows the same pipe as Figure 3 after the expansion of the expandable pipe and material has taken place. 30 In the drawings the reference numeral 1 identities an underground well in a reservoir formation 2. A production pipe 4 including a sand screen 6 is placed in the underground well 1. Well fluid, indicated in Figure I by arrows 8, flows from the 06/02112.dh-19366 - specipg4 -jpw,a - 4b reservoir formation 2 into the production pipe 4 through the sand screen 6. The underground well 1 forms an area of overpressure due to the height of the fluid column of the well. 5 In order to shut off the inflow of fluid into the production pipe 4 from adjacent areas, annular packers 10 have been set. 06/02/12,dh-19366 - specipg4 -jpw,b -5 The annular packers 10, see Figure 2, are made of an elastic material 12 with a considerable portion of closed cavities 14, the material allowing the diffusion of a fluid through the material 12 into the cavities 14. The material 12 may be nitrile rubber, for example. The material 12 may be provided with one or more 5 reinforcements 16, for example in the form of fibre cloth. The annular packer 10 is formed with a somewhat larger transverse dimension than the transverse dimension of the opening which it is to fill. When the annular packer 10 is run into the underground well 1, the cavities 14 of the material are compressed 10 due to an increasing static pressure. Thereby, the annular packer 10 can easily be moved forward into the desired position. The diffusion of fluid through the material 12 into the cavities 14 of the material 12 will start immediately. The cavities 14 are thereby filled, so that the pressure within 15 the cavities 14 will be approximately equal to the prevailing pressure at the annular packer 10. Thereby, the annular packer 10 will attempt to adopt its original shape. If the diameter of the underground well is smaller than the original diameter of the annular packer 10, the annular packer 10 will tighten against the formation wall 18 of the underground well 1, alternatively against a casing, not shown, if the underground 20 well I is cased. In an alternative embodiment, see Figures 3 and 4, an expandable pipe 20 is provided with an encircling sleeve 22 of a material 24 which has open pore-like cavities. Before insertion into the underground well 1, the material 24 of the slee4ve 22 is 25 compressed by means of an encircling preloading material 26. The preloading material 26 may be formed by, for example, a fibre cloth. (This embodiment however is not claimed). After the expandable pipe 20 has been placed in a desired position, the expandable 30 pipe 20 is expanded, whereby the preloading material 26 bursts. 04/08/11, 19366 speci. 5 -6 The expansion of the sleeve 22 then takes place by fluid flowing into the cavities of the material 24, whereby the sleeve 22 is expanded into its original shape. This Application is a divisional of the present Applicant's Australian Patent 5 Application No. 2005248279, and the whole contents thereof are incorporated herein by reference. Throughout this specification and the claims which follow, unless the context requires otherwise, the word "comprise", and variations such as "comprises" and 10 "comprising", will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps. The reference to any prior art in this specification is not, and should not be taken as, 15 an acknowledgment or any form or suggestion that the prior art forms part of the common general knowledge in Australia. 04/08/11, 19366 speci, 6

Claims (19)

1. A method for expanding a body under elevated pressure, the method including the steps of: 5 forming the body from an elastic material with a substantial portion of closed cavities therein; placing the body in an area of elevated pressure, thereby compressing the body; and expanding the body by diffusion of fluid present at the body through the 10 elastic material and into the cavities.

2. The method of claim 1, wherein the body when placed in the area of elevated pressure is compressed by the elevated pressure. 15

3. The method of claim I or claim 2, further including the step of compressing the body using a preloading material before the body is placed in the area of elevated pressure.

4. A device including: 20 an expandable body formed of an elastic material with a substantial portion of closed cavities therein, and which is configured to be placed, in a compressed form, in an area of elevated pressure, and wherein the elastic material includes a diffusible material. 25

5. A method for expanding a body under elevated pressure, the method including the steps of: forming the body from an elastic material with a substantial portion of cavities therein; placing the body in an area of elevated pressure; and 30 expanding the body by diffusion of a fluid through the elastic material and into the cavities, the expanding step further including expanding the cavities by diffusion of the fluid through the elastic material and into the cavities. 06/02/12.dh-19366 - claims -jpw,7 -8

6. The method of claim 5, wherein the body is compressed by the elevated pressure during the placing step. 5

7. The method of any one of claim 5 or claim 6, wherein the cavities are compressed by the elevated pressure during the placing step.

8. The method of any one of claims 5 to 7, wherein the body is compressed by a preloading material before the placing step. 10

9. A device including: a body formed of an elastic material with a substantial portion of cavities therein, wherein the body is compressed and then expanded by diffusion of a fluid through the elastic material and into the cavities, and wherein pressure is egualized 15 between the cavities and an area of elevated pressure by the diffusion of the fluid through the elastic material and into the cavities.

10. A method of sealing in a well, the method including the steps of: positioning an expandable body in the well, the body including a material 20 having cavities therein, the positioning step including applying an elevated pressure to the body; compressing the body, thereby reducing a volume of the body, as a result of the elevated pressure; and then expanding the body into sealing contact with a surface in the well. 25

11. The method of claim 10, wherein the compressing step further includes reducing a volume of the cavities.

12. The method of claim 10 or claim 11, wherein the expanding step further 30 includes increasing a volume of the cavities. 06/02/12,dh-19366 - claims -jpw, 8 -9

13. The method of any one of claims 10 to 12, wherein the expanding step further includes diffusing a fluid through the material surrounding the cavities, whereby the fluid enters the cavities through the material. 5

14. The method of any one of claims 10 to 13, wherein the cavities includes closed cavities.

15. The method of any one of claims 10 to 14, wherein the material includes an elastic diffusible material. 10

16. A method for expanding a body under elevated pressure, substantially as described herein with reference to the accompanying drawings.

17. A method of sealing in a well, substantially as described herein with 15 reference to the accompanying drawings.

18. A device as claimed in claim 4, substantially as described herein with reference to the accompanying drawings. 20

19. A device as claimed in claim 9, substantially as described herein with reference to the accompanying drawings. 25 06/02/12,dh-19366 - claims - jpw,9