DOWNHOLE RETAINER

Abstract

A method of retaining material in a bore comprises running a tool comprising a retainer member and a fusible part into a bore with the retainer member in a retracted configuration. The tool is positioned at a desired location in the bore and the fusible part is heated to reconfigure the retainer member to an extended configuration in which the retainer member engages the bore wall.

Claims

1-32. (canceled)

33. A downhole method comprising: running an apparatus comprising a member and a fusible part into a bore with the member maintained in a retracted configuration by the fusible part; locating the tool at a desired location in the bore, and heating the fusible part and thereby reconfiguring the member to an extended configuration in which the member engages a wall of the bore.

34. The method of claim 33, wherein the member comprises at least one of a retainer member and a grip.

35. The method of claim 33, wherein the fusible part comprises an alloy and heating the fusible part fluidises the alloy.

36. The method of claim 33, wherein heating the fusible part permits release of stored energy and relative movement of elements of the apparatus.

37. The method of claim 33, comprising heating the fusible part with an exothermic heater.

38. A downhole apparatus comprising: a body; a member mounted on the body, the member having an initial retracted configuration and an extended configuration in which the member extends radially from the body, and a fusible part for maintaining the member in the retracted configuration, whereby heating of the fusible part permits reconfiguration of the member from the retracted configuration to the extended configuration.

39. The apparatus of claim 38, wherein the member comprises at least one of a retaining member and a grip.

40. The apparatus of claim 38, wherein the fusible part comprises an alloy member.

41. The apparatus of claim 38, wherein the fusible part is initially in at least one of compression, tension and shear, and on heating at least one of melts, otherwise reforms and deforms to permit relative movement of elements of the apparatus.

42. The apparatus of claim 38, wherein on heating the fusible part permits release of stored energy to reconfigure the member.

43. The apparatus of claim 38, in combination with a heater.

44. The apparatus of claim 38, wherein the member comprises a retainer disc which is elastically deformed in the retracted configuration.

45. The apparatus of claim 38, wherein the member comprises at least one slip.

46. The apparatus of claim 38, wherein the member comprises a deformable disc, in the initial retracted configuration the disc being elastically deformed and radially restrained, whereby on removal of the radial restraint the disc extends radially from the body.

47. The apparatus of claim 46, wherein the disc is restrained by a sleeve and is released by relative axial movement of the disc and sleeve.

48. The apparatus of claim 46, wherein the disc comprises multiple petals.

49. The apparatus of claim 46, wherein the member comprises a deformable metal disc.

50. The apparatus of claim 46, wherein the member comprises multiple deformable discs.

51. The method of claim 33, wherein the member comprises a deformable disc of a first diameter and the method further comprises: elastically deforming the disc from the first diameter to describe a smaller second diameter and restraining the disc at the second diameter; running the disc into the bore; and releasing the disc to describe a third diameter larger than the second diameter and whereby the disc engages an inner wall of the bore.

52. The method of claim 51, wherein when describing the third diameter portions of the disc are arranged at an acute angle to the bore wall, so that the disc forms a cup shape.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Examples of the disclosure will now be described, by way of example, with reference to the accompanying drawings, in which:

[0047] FIGS. 1 & 2 are sectional views of a downhole material retainer; and

[0048] FIGS. 3a, 3b & 3c show alternative metal sealing discs for the retainer of FIGS. 1 & 2.

DETAILED DESCRIPTION OF THE DRAWINGS

[0049] Reference is made to FIGS. 1 & 2, and FIGS. 3a, 3b & 3c, which show a downhole material retainer 122. FIG. 1 illustrates the retainer 122 in a first configuration, with a retainer or sealing disc 124 and bore wall grips/slips 126 retracted. FIG. 2 illustrates the retainer 122 in an activated configuration, with the sealing disc 124 and the slips 126 radially extended.

[0050] The retainer 122 includes an axially extending coil spring 128 which is initially compressed to provide stored energy to activate the retainer 122. The spring 128 abuts an anchor piston 132. The lower end of the spring 128 engages a bottom sub 136. The anchor piston 132 is coupled to an upper mandrel 138 upper end portion 140. The upper mandrel 138 is formed of a suitable material, such as steel, while the mandrel upper end portion 140 is formed of an alloy, metal or other material having a significantly lower melt point than steel.

[0051] A bullnose 150 is mounted on the lower end of the bottom sub 136.

[0052] The retainer disc 124 is mounted on the upper body 146 and is retained on the body by an axial support. In the first configuration, as illustrated in FIG. 1, the retaining disc 124 is restrained in a deformed retracted configuration by a retainer sleeve 154 which extends over the retaining disc 124.

[0053] The slips 126 are also mounted on the upper body 146 and are provided on slip arms 158 pinned to the body 146 such that the slips 126 may be pivoted out to engage the surrounding steel tubing 101. The movement of each slip arm 158 is driven by the anchor piston 132, which is powered by the spring 128.

[0054] Activation of a heater 116 (discussed in greater detail below), generates elevated temperatures and fluidises the alloy upper end portion 140 of the mandrel 138. As the mandrel 138 is in compression from the action of the spring 128, on melting the fluidised alloy mandrel portion 140 collapses and allows the spring 128 to move the anchor piston 132 and the upper mandrel 138 upwards relative to the upper body 146.

[0055] The movement of the upper mandrel 138 relative to the upper body 146 releases the retaining disc 124 from the disc retainer 154, such that the disc 124 is free to extend and engage the surrounding tubing 101. However, the disc 124 is prevented from fully extending by contact with the tubing 101 and is restrained to extend at an acute angle from the body 146, forming a cup-like form. Similarly, the slip arms 158 are pivoted outwards to engage the slips 126 with the tubing 101.

[0056] FIGS. 3a, 3b & 3c illustrate different forms of retaining disc 124a, 124b, 124c. The discs are formed of thin metal or other deformable material, such as molybdenum foil, plastic, felt, steel or the like. The discs include radial cuts 168 such that the discs comprise multiple petals, which facilitates the deformation of the discs 124a-c to the retracted configuration without the discs 124a-c experiencing plastic deformation, that is the discs 124a-c are deformed elastically.

[0057] A single disc 124 may be provided in the retainer 122, or multiple discs 124 of the same or different materials may be provided to create a laminate structure.

[0058] FIGS. 1 & 2 also illustrate the heater 116 and a cable anchor 170. The heater defines an annular form around a central body portion 174 defining the chamber 142 which accommodates and restrains the alloy mandrel upper end portion 140. The heater module 172 may comprise a thermite mix and contain an electrical initiation means which is powered by ignition wire which runs through the support cable 118.

[0059] The cable 118 may be tensioned to facilitate a connection with an adjacent tool string component. The lower end of the cable 118 is fixed in the cable anchor/socket 170, which is formed of fusible alloy. The socket 170 is secured in the body portion 174. The cable 118 extends upwards from the socket 170 to the adjacent tool string component.

[0060] When power is supplied to the heater 116 the heating elements (electric or exothermic) in the module 172 heats and fluidises the alloy mandrel upper end portion 140, thus activating the retainer 122. The retaining disc 124 extends from the retainer 122 to engage and seal with the tubing 101 and the slips 126 also extend to grip the tubing 101. As the heat moves upwards, the cable socket 170 is also heated and soon melts to release the lower end of the cable 118. As the cable 118 was in tension, on release of the cable 118 from the socket 170 the lower end of the cable 118 is pulled upwards releasing the retainer 122 from the adjacent tool string component. Further, as the slips 126 have been extended to engage the tubing 101 and the rope socket 170 has melted, the cable 118 now no longer supports the retainer 122 and the heater 116, which significantly reduces the load being suspended from the wireline. Thus, the wireline will axially contract, separating the tool above the heater.

[0061] In certain tool string configurations cement, or another material, may now be bailed on top of the retainer 122. In other tool string configurations thermite and/or alloy may be deposited on the retainer 122. This may be performed immediately following the setting of the retainer 122. The molten material, under the influence of gravity, will tend to flow downwards and accumulate above the retainer 122. The characteristics of the molten thermite reaction products may be adjusted by controlling the elements of io the initial thermite mix, and in one example the thermite is formulated to fluidise and flow downwards. The molten alloy may form a seal above the thermite and may fuse with and fill voids in and around the thermite reaction products. The molten alloy may continue to flow downwards until the alloy encounters the extended retainer disc 124. The thermite and alloy will thus be retained above the disc 124 and will settle in the tubing 101 to fill the volume above the disc 124. The dense alloy will displace any well fluid and will occupy any voids or spaces in the thermite reaction products and in the elements of the upper part of the retainer 122 and the heater 116 which are not melted.

[0062] In other examples of the disclosure alternative or additional fusible members or elements may be provided. For example, a shear coupling comprising fusible material may be provided and may initially fix two parts relative to one another. On heating, the coupling, which may take the form of a pin, may fail and permit relative movement of the parts, and extension of a retaining disc or slips. In another example a retaining sleeve, ring or band comprising fusible material may encircle or otherwise restrain a retaining disc or slips which are biased to assume an extended configuration. On heating the fusible material may soften or flow and allow the disc or slips to extend,

[0063] In one specific example the illustrated mandrel upper end portion 140 may be replaced by an aluminium shear pin which extends across the chamber 142 and restrains the upper end of the mandrel 138. On heating, the pin softens and shears, allowing the spring 128 to move the anchor piston 132 and the upper mandrel 138 upwards relative to the upper body 146. In other examples the shear pin may be formed of an alloy, for example brass. In another example a small cross section or hollow steel pin may be provided.

[0064] In the illustrated example a cable 118 is fixed in a fusible cable anchor/socket 170, which is secured in the body portion 174. In another examples the cable 118 is replaced by a rod or tube. In one example a steel tube with a threaded end engages a threaded anchor. On activation the adjacent heater creates liquid thermite, which severs and releases the end of the rod.

REFERENCE NUMERALS

[0065] steel tubing 101 [0066] thermite initiator 116 [0067] support cable 118 [0068] retainer 122 [0069] retaining disc 124 [0070] grips/slips 126 [0071] spring 128 [0072] anchor piston 132 [0073] bottom sub 136 [0074] upper mandrel 138 [0075] mandrel upper end portion 140 [0076] initiator chamber 142 [0077] upper retainer body 146 [0078] bullnose 150 [0079] disc retainer 154 [0080] slip arms 158 [0081] cuts 168 [0082] cable anchor/socket 170 [0083] initiator module 172 [0084] central body portion 174