Downhole tool with a propellant charge

Abstract

A tool for manipulating a tubular, such as casing or production tubing, in a downhole environment, is described. The tool comprises a housing defining a chamber, the chamber having at least one outlet, a propellant source located within the chamber and an ignition mechanism for igniting the propellant source. Upon ignition of the propellant source, the propellant deflagrates, creating at least one stream of combustion products, the chamber directing the stream of combustion products through the/each outlet, towards the tubular to be manipulated, the/each stream of combustion products combining with at least one modifying agent to manipulate the tubular.

Claims

1. A tool for manipulating a tubular in a downhole environment, the tool comprising: a housing defining a chamber, the chamber having at least one outlet; a propellant source located within the chamber; an ignition mechanism for igniting the propellant source; and at least one modifying agent provided in or adjacent the tool or generated by the tool; wherein upon ignition of the propellant source, the propellant source is adapted to deflagrate, creating at least one stream of combustion products, the chamber directing the stream of combustion products through the/each outlet, towards the tubular to be manipulated, the/each stream of combustion products combining with at least one modifying agent to manipulate the tubular.

2. The tool of claim 1, wherein in use, the at least one modifying agent cracks, displaces, erodes, ablates, abrades or removes at least a portion of the tubular to be manipulated.

3. The tool of claim 1, wherein the propellant source comprises a plurality of propellants.

4. The tool of claim 1, wherein the propellant source is formed of the combination of two or more materials within the tool.

5. The tool of claim 1, wherein the propellant source is arranged to create an intermittent stream of combustion products.

6. The tool of claim 1, wherein at least one of the at least one modifying agent is formed by the combustion of the propellant source.

7. The tool of claim 1, wherein at least one of the at least one modifying agent is formed separately from the combustion of the propellant source.

8. The tool of claim 1, wherein at least one of the at least one modifying agent is present prior to ignition of the propellant source.

9. The tool of claim 1, wherein at least one of the at least one modifying agent is present within the propellant source.

10. The tool of any claim 1, wherein at least one of the at least one modifying agent is aluminum oxide.

11. The tool of claim 1, wherein at least one of the at least one modifying agent reacts with the environment and/or the tubular to be modified.

12. The tool of claim 1, wherein at least one of the at least one modifying agent is introduced into the stream of combustion products.

13. The tool of claim 1, wherein at least one of the at least one modifying agent is drawn into the stream of combustion products by a venturi or similar geometric profile.

14. The tool of claim 1, wherein at least one of the at least one modifying agent is mechanically or forcibly introduced into the propellant gas and/or stream of combustion products.

15. The tool of claim 1, wherein at least one of the at least one modifying agent is applied to the surface of the tubular to be manipulated.

16. The tool of claim 1, wherein at least one of the at least one modifying agent is a flux.

17. A method of manipulating a tubular in a downhole environment, the method comprising: positioning a tool having a housing defining a chamber, the chamber having at least one outlet; a propellant source located within the chamber; and an ignition mechanism for igniting the propellant source adjacent a tubular to be manipulated, igniting the propellant source such that at least one stream of combustion products is generated, the chamber directing the/each stream of combustion products through the/each outlet, the outlet directing the/each stream of combustion products towards the tubular to be manipulated, the/each stream of combustion products including a modifying agent to modify the tubular to be manipulated.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) embodiments of the present invention will now be described with reference to the accompanying drawings in which:

(2) FIG. 1 is a side view of a tool for manipulating casing shown positioned in a section of a well according to a first embodiment of the present invention;

(3) FIG. 2 is a section of the tool FIG. 1;

(4) FIG. 3 is a section of the tool of FIG. 1 during deflagration of the propellant source;

(5) FIG. 4 is a section of the tool of FIG. 1 during deflagration of the propellant source;

(6) FIG. 5 is a section of the tool of FIG. 1 during deflagration of the propellant source;

(7) FIG. 6 is a section of the well of FIG. 1 after the tool has been removed and a cement plug fitted;

(8) FIG. 7 is a side view of a tool for manipulating casing shown positioned in a section of a well according to a second embodiment of the present invention;

(9) FIG. 8 is a section of the tool FIG. 7;

(10) FIG. 9 is a section of the tool of FIG. 7 during deflagration of the propellant source;

(11) FIG. 10 is a section of the tool of FIG. 7 during deflagration of the propellant source;

(12) FIG. 11 is a section of the well of FIG. 7 after the tool has been removed;

(13) FIG. 12 is a section of the well of FIG. 7 following installation of a cement plug; and

(14) FIG. 13 is a section of a tool for manipulating casing shown positioned in a well during deflagration of the tool's propellant source according to a third embodiment of the present invention.

DETAILED DESCRIPTION OF THE DRAWINGS

(15) Reference is first made to FIG. 1, a side view of a tool, generally indicated by reference numeral 10, for manipulating casing 12 in a well 14 according to a first embodiment of the present invention. The casing 12 is shown attached to bedrock 16 by cement 18. Particularly, the tool 10 is for removing a section of the casing 12 and the cement 18 attaching the casing to the bedrock 16, to permit a cement plug to be installed in this section in advance of the well 14 being abandoned.

(16) The tool 10 is lowered in to the well on a wireline 19 and anchored in position by three circumferentially displaced anchors 46 (of which one is visible on FIG. 1) to prevent axial movement of the tool 10, as will be explained in due course.

(17) Additionally referring to FIG. 2, a section through the tool 10 of FIG. 1, it can be seen that the tool 10 comprises a housing 20 defining a chamber 22, the chamber 22 having a series of outlets 24 in the form of nozzles.

(18) Inside the chamber 22 is a propellant source 26 containing a propellant 27 and particles of a modifying agent 28, in this case aluminium oxide. The propellant source 26 has a coating 30 which defines an opening 32 at an end of the coating 30, the opening 32 exposing a section 36 of the propellant 27 to the interior of the chamber 22. Adjacent the exposed propellant section 36 is an ignition mechanism 38 adapted to ignite the propellant section 36.

(19) Directly below the propellant 27 is a deflector plate 39 defining a profiled deflection surface 40, the deflection surface 40 being profiled to direct a flow towards the outlets 24.

(20) Operation of the tool 10 will now be described with reference to FIGS. 3 and 4, sections of the tool 10 of FIG. 1 showing the tool 10 in use. Referring firstly to FIG. 3, with the anchors (not shown in this Figure) in place, the ignition mechanism 38 has ignited the exposed propellant section 36 creating a combustion zone 42 on the propellant source 26. As the propellant 27 deflagrates, a stream of highly pressurised combustion products 44 is released. The stream of combustion products 44 is driven downwards away from the propellant 27 due to the pressure within the stream 44 and, in particular, generated at the combustion zone 42. Within the stream of combustion products 44 are the particles 28 of aluminium oxide which have been released from the propellant source 26. The thrust created by the stream of combustion products 44 is prevented from driving the tool 10 upwards by the anchors 46, therefore the thrust drives the stream 44 and the particles 28 towards the deflector plate 39.

(21) The stream of combustion products 44 containing the particles 28 impacts on the deflector plate 39 and are deflected along the deflection surface 40 towards the outlets 24. The combustion products 44 and the particles 28 are funnelled through these nozzles 24 and impact on the casing 12.

(22) The four nozzles 24 are spaced equidistant around the circumference of the housing 20, the nozzles 24 being arranged in opposed pairs. This arrangement keeps the tool 10 centralised in the well 14 as the thrust generated at each nozzle 24 is countered by the thrust generated by the nozzle 24 on the opposite side of the housing 20. However, the nozzles 24 are angled to the radius of the tool 10 such that the thrust generated by the nozzles 24 cause the tool 10 to rotate, such that the stream of combustion products 44 and the associated particles 28 cut a circumferential ring through the casing 12.

(23) The stream of combustion products 44 has burned the aluminium oxide particles 28 such that they have sapphire-like properties. The stream of combustion products 44 has also accelerated the particles 28 and this combination of speed and heat induced change of properties results in the particles 28 carving into the casing 12 by displacing the casing material. In addition the stream of combustion products 44 heats the casing 12, facilitating the removal of material by the particles 28.

(24) Referring to FIG. 4, the removal of the casing 12 strips back the casing 12 leaving exposed regions 60 of cement 18.

(25) Referring to FIG. 5, as propellant source 26 deflagrates, the coating 30 burns with it, exposing new propellant 27 to the combustion zone 42. With the deflagration of the propellant source 26 under control, the anchors 46 can be partially released to permit the tool 10 to rise slowly of the well 14 and create an extended section of exposed cement 18.

(26) Once the propellant source 26 is exhausted, the exposed cement 18 can be removed. This cement 18 is weakened by the heat and the tool 10 is run in again (not shown) and the anchors 46 are applied to the weakened cement, causing the cement 18 to crumble and fall away leaving an exposed section 62 of bedrock 16 (FIG. 6).

(27) This exposed section 62 can then be plugged with a cement plug 64 permitting the well 14 to be abandoned.

(28) Reference is now made to FIG. 7, a tool 110 for manipulating casing 112 in a well 114 according to a second embodiment present invention.

(29) The arrangement of the tool 110 and the surrounding well 114 is similar to that of the first embodiment and similar reference numerals have been used, incremented by 100. The tool 110 is for a similar purpose; that is to strip a section of casing 112 and associated cement 118 from bedrock 116.

(30) The tool housing 120 includes an elongate lattice outlet arrangement 124. The outlet arrangement 124 extends the entire length of the housing 120.

(31) Referring to FIG. 8, a section through the tool 110 of FIG. 7, this Figure shows the propellant source 126 as being much wider than the propellant source 26 of the first embodiment, the propellant source 126 filling the entire width of the housing 120.

(32) Beneath the propellant source 126 is a void 154, the purpose of which will be discussed in due course.

(33) As can be seen most clearly from FIGS. 7 and 8, the outlet 124 contains a frangible seal 150 which extends up the outlet 124 to above the top of the void 154. From the top of the seal 150 upwards, the outlet 124 is sealed by the propellant source covering 130. It will be noted there is no deflector plate on this embodiment.

(34) The tool 110 of this embodiment further includes upper and lower packer seals 156, 158 for sealing a wellbore section 160.

(35) Operation of the tool 110 will now be discussed. The tool 110 is lowered into position and the upper and lower packers 156, 158 are set to seal the wellbore section 160. It is in the section 162 that the casing 112 is to be manipulated.

(36) Referring to FIG. 9, the ignition mechanism 138 (shown on FIG. 8) is activated and this ignites the exposed propellant section 136 creating a stream of combustion products 144 which fill the void 154. Pressure builds up inside the void 154 until a threshold pressure is reached which overcomes the strength of the frangible seal 150 breaking the seal and allowing the stream of combustion products to flow through the outlet 124.

(37) As the outlet 124 is a slot rather than a circular nozzle, the flow of combustion products 144 comes out as a blade 180 rather than as a jet.

(38) The housing 120 is made of a sacrificial material. As the flow of combustion products 144 passes through the outlet, the flow 144 skims off the housing edges 182 which define the outlets 124. A sacrificial material comes off in particulate form and becomes entrained in the flow 144, the particles 128 acting as the modifying agent 128 which is propelled onto the surface of the casing 112 to strip back the casing 112, leaving exposed regions of cement 160.

(39) Referring to FIG. 10, a section view of the tool 110 of FIG. 7, as the propellant source 126 deflagrates, the coating 130 burns with it revealing more of the outlet 124.

(40) Referring to FIG. 11, a section through the well 114 after the casing 112 has been stripped back to the cement 118 by the tool 110 of FIG. 7, once the propellant source 126 has fully deflagrated, a lattice arrangement of grooves 184 carved into the casing 112 showing the exposed cement 118.

(41) Application of mechanical force, for example, on the well section 162 will remove the remaining casing fragments 186 and the exposed cement 118. Then, as per the first embodiment, a cement plug 164 can be installed in the well section 162, permitting the well 114 to be abandoned.

(42) Reference is now made to FIG. 13, a tool 210 for manipulating casing 212 in a well 214 according to a third embodiment present invention.

(43) The arrangement of the tool 210 and the surrounding well 214 is similar to that of the first embodiment and similar reference numerals have been used, incremented by 200. The tool 210 is for punching holes in a section of casing 212 and associated cement 218 through to the bedrock 216.

(44) The primary differences between the tool 210 of this embodiment and the tool 10 of the first embodiment resides in, first, the outlets of the tool 210 being in the form of nozzles 224 which extend around the circumference of the tool 210. These nozzles 224 are directed downwardly to maximise the effect of moving casing material by impacting the casing at an acute angle.

(45) The second difference resides in the deflector plate 239 which is a sacrificial plate from which the stream of combustion products 244 scours off the modifying agent 228. The stream of combustion products 244 with the entrained modifying agent 228 punch a ring of holes 290 through the casing 212 and cement 218.

(46) Various modifications may be made to the above-described embodiments without departing from the scope of the invention. For example the nozzles may change the characteristics of the stream of combustion products by, for example, being cooled or being impregnated with material or being sonically resonated or by having a surface which is textured or grooved.

(47) In other embodiments, the stream of combustion products may impart additional energy to the tubular. This energy may be in the form of heat. Additionally, the stream of combustion products may exert a pressure on the tubular. Alternatively or additionally the combustion products may exert a force on the tubular. For example, particulate within the combustion products and carried within the stream may impact the surface of the tubular and exert a force. This additional energy can be used to dislodge the manipulated casing and the associated cement securing it to the bedrock. There may be more than one mode of interaction with the tubular. For example, the tubular may be heated to melting point while at the same time subjected to pressure.

(48) In further embodiments, the combustion products may enhance thermal conductivity by forming a flux or thermally conductive layer at the tubing or the combustion products may react at the tubular or in transit to the tubular. For example, particles may chemically react or combust at the tubing.