HEAT SOURCES AND ALLOYS FOR USE IN DOWN-HOLE APPLICATIONS

Abstract

A chemical reaction heat source for use in heaters used in down-hole applications is provided. The heat source has a fuel composition that comprises thermite and a damping agent. The use of the termite mix enables the heaters of the present invention to generate hotter temperatures down wells. This in turn allows the use of Bismuth/Germanium alloys, which have higher melting points, to enable the production of plugs for the abandonment of deeper wells where subterranean temperatures are higher.

Claims

1-22. (canceled)

23. A plug tool comprising: a thermite composition; and, a plug material comprising an alloy including bismuth and germanium.

24. The plug tool of claim 23, wherein the alloy comprises no more than about 1% germanium by weight.

25. The plug tool of claim 23, wherein the alloy comprises no more than about 10% germanium by weight.

26. The plug tool of claim 23, wherein the alloy comprises no more than about 20% germanium by weight.

27. The plug tool of claim 23, wherein the alloy includes a further metal.

28. The plug tool of claim 27, wherein the further metal is copper.

29. The plug tool of claim 23, wherein the plug tool suits an underground conduit or a well.

30. The plug tool of claim 23, further comprising a damping agent.

31. The plug tool of claim 30, the damping agent is sand.

32. The plug tool of claim 30, wherein the plug tool is in a form of one or more blocks.

33. The plug tool of claim 30, wherein the plug tool of in a powdered form.

34. The plug tool of claim 32, wherein each block has a pre-determined ratio of the thermite to the damping agent that determines a heating capability of said block.

35. The plug tool of claim 32, wherein the plug tool includes a plurality of blocks with a range of pre-determined ratios of the thermite to the damping agent.

36. The plug tool of claim 35, wherein the plurality of blocks with the pre-determined ratios are arranged in series so that each block ignites in accordance with a pre-arranged order.

37. The plug tool of claim 35, wherein the plurality of blocks are arranged in a stack in a way that faster reacting blocking are arranged in a middle of the stack.

38. The plug tool of claim 35, wherein the plurality of blocks are arranged in a stack in a way that faster reacting blocking are arranged towards a bottom of the stack.

39. A well abandonment system comprising: a heater that comprises a chemical reaction heat source having a fuel composition that comprises a thermite composition and a plug material comprising an alloy including bismuth and germanium.

40. The system of claim 39, wherein the alloy comprises no more than about 1% germanium by weight.

41. The system of claim 39, wherein the alloy comprises no more than about 10% germanium by weight.

42. The system of claim 39, wherein the alloy comprises no more than about 20% germanium by weight.

43. The system of claim 39, wherein the alloy includes a further metal.

44. The system of claim 43, wherein the further metal is copper.

45. The system of claim 39, the fuel composition further comprises a damping agent.

46. The system of claim 45, the damping agent is sand.

47. The system of claim 45, wherein the fuel composition is in a form of one or more blocks.

48. The system of claim 45, wherein the fuel composition of in a powdered form.

49. The system of claim 45, wherein each block has a pre-determined ratio of the thermite to the damping agent that determines a heating capability of said block.

50. The system of claim 45, wherein the fuel composition includes a plurality of blocks with a range of pre-determined ratios of the thermite to the damping agent.

51. The system of claim 50, wherein the plurality of blocks with the pre-determined ratios are arranged in series so that each block ignites in accordance with a pre-arranged order.

52. The system of claim 50, wherein the plurality of blocks are arranged in a stack in a way that faster reacting blocking are arranged in a middle of the stack.

53. The system of claim 50, wherein the plurality of blocks are arranged in a stack in a way that faster reacting blocking are arranged towards a bottom of the stack.

54. A method of tailoring a well abandonment system to suit an underground conduit or well comprising: a) assessing down-hole environmental characteristics of the underground conduit or well that is to be plugged; b) selecting an alloy including bismuth and germanium suitable to produce a stable plug within the environment of the underground conduit or well; c) providing a chemical reaction heat source suitable to melt the selected bismuth alloy, said heat source having a fuel composition that comprises thermite and a damping agent; and d) producing a tailored well abandonment system comprising the selected bismuth alloy and provided chemical reaction heat source.

55. The method of claim 54, wherein the alloy comprises no more than about 1% germanium by weight.

56. The method of claim 54, wherein the alloy comprises no more than about 10% germanium by weight.

57. The method of claim 54, wherein the alloy comprises no more than about 20% germanium by weight.

58. The method of claim 54, wherein the alloy includes a further metal.

59. The method of claim 58, wherein the further metal is copper.

60. The method 54, the damping agent is sand.

61. The method of claim 54, wherein the fuel composition is in a form of one or more blocks.

62. The method of claim 54, wherein the fuel composition of in a powdered form.

63. The method of claim 62, wherein each block has a pre-determined ratio of the thermite to the damping agent that determines a heating capability of said block.

64. The method of claim 54, wherein the fuel composition includes a plurality of blocks with a range of pre-determined ratios of the thermite to the damping agent.

65. The method of claim 64, wherein the plurality of blocks with the pre-determined ratios are arranged in series so that each block ignites in accordance with a pre-arranged order.

66. The method of claim 64, wherein the plurality of blocks are arranged in a stack in a way that faster reacting blocking are arranged in a middle of the stack.

67. The method of claim 64, wherein the plurality of blocks are arranged in a stack in a way that faster reacting blocking are arranged towards a bottom of the stack.

Description

DESCRIPTION OF THE DRAWINGS

[0037] The present invention will now be described with reference to the drawings, wherein:

[0038] FIG. 1 shows an arrangement of heating blocks suitable for a plug deployment heater;

[0039] FIG. 2 shows an arrangement of heating blocks suitable or a plug retrieval heater;

[0040] FIG. 3 shows phase diagram for various mixes of Bismuth/Germanium alloys.

DESCRIPTION OF THE VARIOUS ASPECTS OF THE PRESENT INVENTION

[0041] It is envisaged that the various aspects of the present invention can be use alone or in combination with one another to provide real benefits in the plugging of underground conduits. It is envisaged that although the present invention is particularly applicable in plugging both vertical and non-vertical wells (with or without well casings) the heaters of the present invention have characteristics which make that suitable for a range of other down-hole applications.

[0042] For example the described aspects can be used together with the methods and apparatus described in WO2011/151271 to facilitated the squeezing off and repairing of wells.

[0043] Whilst the various aspects of the present invention are considered particularly applicable to the plugging of oil and gas wells it is envisaged that they would provide benefits when plugging other forms of underground conduits such as water pipes for example.

[0044] In a preferred embodiment of the chemical reaction heat source at the present invention the fuel composition is provided in the form a stacked arrangement of blocks that, in use, are housed within a heater body. Each block is capable of generating a certain level of heat, the level of which is predetermined by the ratio of thermite to damping agent (e.g. sand) in the composition mix of that particular block.

[0045] It is envisioned that a range of predetermined mixes, which are capable of generating a range of predetermined temperatures, are produced by varying the levels of then mite from 99% to 1% by mixing the thermite with a damping agent. The damping agents (or combustion suppressing agents as it may also be referred to herein) preferably take the form of silica or sand. However it is envisioned that alternative forms of damping agent may also be adopted without departing from the general inventive concept of the present invention.

[0046] It is appreciated that by arranging blocks with differing heating abilities in specific stacking orders it is possible to create a chemical reaction heat source that generate heating pattern appropriate to the type of heater it is being used in.

[0047] FIGS. 1 and 2 each how an example of a chemical reaction heat source, 1 and 5, with a block stacking arrangement that creates a distinct heating pattern.

[0048] For the ease of understanding the heating power of each block has been assigned a number from 0 to 5, wherein 0 burns faster and therefore hotter and 5 burns slower and therefore cooler. Although the ratio of thermite to damper agent in each point of the scale is not specifically identified herein it envisioned that the hottest level 0 may be provided by almost pure thermite. The coolest level (i.e. 5) may be provided by a mix predominately made from a damping agent (e.g. sand).

[0049] It will be appreciated that the ratios of the mixes used to achieve the heating powers of 1 to 4, for example, will therefore vary between the two end points set by the mixes of heating power 0 and heating power 5.

[0050] In both of the examples shown the region nearest to the igniter 3 (shown as 0) has the highest level of thermite (virtually 100%) so as to ensure that the chemical reaction gets off to the best start. It is envisioned that, due to the of the pure thermite, the starter block may be smaller than the other blocks in the stack.

[0051] Although not shown it is also appreciated that pure thermite powder may be provided in and around the region where the igniter and the first block come into contact. In this way the chemical reaction is given the best chance of being successfully initiated.

[0052] FIG. 1 shows a diagram of an arrangement of fuel composition blocks that provides a chemical reaction heat source that is particularly suited to a he at for deploying Bismuth-based plugs such as those described in WO2011/151271.

[0053] The arrangement shown in FIG. 1, which arranges the aster/hotter reacting blocks in the middle of the stack, is particularly suited to the task of deploying a Bismuth-based plug because the main focus of the heat in the heating pattern 4 is the middle of the heater, which, when the heater is engaged with a plug, is aligned to the location of un-melted alloy.

[0054] In addition, the provision of the coolest block at the base of the stack helps to direct the heat away from the base of the heater. This is important because this is the area where the melted alloy will start to cool down and expand against the sides of an underground conduit to form the required plug. Thus shielding this region from the heat source is advantageous.

[0055] Although not shown in the figures, it is envisaged that pure damping agent may be provided at the base of the heater stack shown in FIG. 1 to further shield the base region of the heater and the corresponding region of a plug.

[0056] FIG. 2 shows a diagram of an arrangement of fuel composition blocks 5 that provides a chemical reaction heat source that is particularly suited to a heater for retrieving Bismuth-based plugs such as those also described WO2011/1151271.

[0057] The arrangement 5 shown in FIG. 2, which arranges the faster and hotter reacting blocks (e.g. heating power 1) towards the bottom of the stack, is particularly suited to the task of retrieving a Bismuth-based plug that is in-situ within a well because the main focus of the heat 6 is towards the base of the heater, which, when the heater is engaged with a plug, is aligned the location of alloy plug.

[0058] IT will be appreciated that the present invention allows the heating characteristics of a given heater to be tine-tuned to better suit the particular needs of any given down-hole task by effectively adjusting the arrangement blocks to achieve the most appropriate heating pattern.

[0059] In view this the present invention also provides a method of tailoring a well abandonment system (i.e. a heater) to suit a particular underground conduit or well.

[0060] This method essentially comprises: [0061] a) assessing the down-hole environmental characteristics of the underground conduit or well that is to be plugged; [0062] b) selecting a Bismuth alloy suitable to produce a stable plug within the environment of the underground conduit or well; [0063] c) providing a chemical reaction heat source suitable to melt the selected Bismuth alloy, said heat source having a fuel composition that comprises thermite and a damping agent; [0064] d) producing a tailored well abandonment system comprising the selected Bismuth alloy and provided chemical reaction heat source.

[0065] It is appreciated that there are a range of down-hole environmental characteristics that may have a bearing on what type of heater and/or plug is required tor the job. Some of the most relevant characteristics are: [0066] 1) Temperature in the region of the underground conduit where the plug is to be deployed; [0067] 2) Pressure in the region of the underground conduit where the plug is to be deployed; [0068] 3) Differential pressure requirement of the plug, now and in the future; [0069] 4) Well bore fluid; [0070] 5) Well completion characteristics.

[0071] It is envisioned that Bismuth/Germanium alloys may be adopted due to the enhanced heating capabilities realised by the thermite-based heat sources of the present invention.

[0072] FIG. 3 shows how the melting temperature of an alloy can be controlled by varying the ratio of Bismuth to Germanium in the alloy. It will be appreciated from the data shown that the introduction of Germanium has a marked effect on the melting temperature up to about 20% by weight, after which the temperature increasing effects are less marked.

[0073] The present invention also provides for a method of tailoring a plug retrieval heater system that involves assessing the nature of the alloy of the plug that is to be retrieved from the underground conduit and then providing a chemical reaction heat source suitable to melt the alloy, said heat source having a fuel composition that comprises thermite and a damping agent.