Bismuth and cement method of abandoning a well and means of real time verification of the bismuth and cement placement process

Abstract

A method of abandoning a well, where the well is at least a length of tubing, and a first annulus outside the tubing, comprising the steps of puncturing a hole or holes in the tubing, the holes in the

Description

[0001] Bismuth and Cement Method of Abandoning a Well and Means of Real Time Verification of the Bismuth and Cement Placement Process

[0002] Over the past 20 years or so a large number of offshore structures have been constructed which are now or will soon be exhausted and will need to be abandoned. These offshore structures may comprise production platforms which are either steel or concrete structures resting on the seabed or floating platforms. Numerous conduits are connected to these offshore structures to carry the various fluids being gas, oil or water etc., which are necessary for the production of oil and / or gas from the well.

[0003] In abandoning a well, consideration has to be given to the potential environmental threat from the abandoned well for many years in the future.

[0004] In the case of offshore structure there is usually no rig derrick in place which can be used to perform the required well abandonment procedure. Therefore, it is typically necessary to install a new derrick or alternatively a mobile derrick can be positioned above the well. This requirement adds considerable expense to the task of abandoning the offshore well, compared to a land based well.

[0005] A typical production well will comprise a number of tubular conduits arranged concentrically with respect to each. The method of abandoning the well which is presently known in the art involves the separate sealing of each of the concentric conduits which requires a large number of sequential steps.

[0006] In the abandonment method known in the art the first step is to seal the first central conduit usually by means of cement or other suitable sealant. The first annular channel between the first and second conduits is then sealed and the first central conduit is then cut above the seal and the cut section is removed from the well.

[0007] The second annular channel between the second and third conduits is then sealed and the second conduit cut above the seal and the cut section is removed from the well. This process is repeated until all the conduits are removed. The number of separate steps required is typically very large indeed and the number of separate operations is five times the number of conduits to be removed. This adds considerably to the cost of the well abandonment due to the time taken and the resources required at the well head.

[0008] It is the purpose of the present invention to provide a method of abandoning a well which avoids the disadvantageous and numerous operations which are required by the existing known methods. This will greatly reduce the costs of safely abandoning a well. It is a further objective of the invention to provide a method of abandoning a well without the requirement of a rig which involves significant expense particularly in subsea based wells.

[0009] According to the present invention there is provided a method of abandoning a well, by using a tool to puncture holes in the tubing to gain access to the annulus immediately outside it (annulus A)

[0010] According to a further aspect of the invention there is provided a method of abandoning a well, by using a tool to puncture holes in the tubing and the casing outside it to gain access to the annulus immediately outside it, and the annulus outside it (annulus A & B)

[0011] According to a further aspect of the invention, the hole could puncture by mechanical means

[0012] According to a further aspect of the invention, the hole could puncture by explosive means

[0013] According to a further aspect of the invention, the hole could puncture by a laser means

[0014] According to a further aspect of the invention, the hole could puncture by thermite plasma means According to a further aspect of the invention, there is provided a tool to heat the inside of the tubing

[0015] According to a further aspect of the invention, there is provided a tool to heat the inside of the tubing using a thermite heat source

[0016] According to a further aspect of the invention, there is provided a tool to heat the inside of the tubing using a electrical heat trace heat source

[0017] According to a further aspect of the invention, bismuth beads are deposited on the heat source

[0018] According to a further aspect of the invention, bismuth beads are conveyed in a container above the heat source

[0019] According to a further aspect of the invention, bismuth beads are deposited from surface using gravity

[0020] According to a further aspect of the invention the bismuth may be cast onto the heating element and conveyed into the well by the heating element

[0021] According to a further aspect of the invention, bismuth beads melt around the heat source, and flow out of the holes punched into the tubing.

[0022] According to a further aspect of the invention the bismuth solidifies quickly as it drops down the outside of the tube, and eventually forms a solid platform in the annulus A

[0023] According to a further aspect of the invention, as the fluid is displaced in the annulus, the bismuth retains more heat and can convey this heat to the casing outside it.

[0024] According to a further aspect of the invention, bismuth the fluid bismuth can enter the holes in the next casing and form a platform in the annulus B According to a further aspect of the invention, the column of bismuth provides positive weight to enable all the annulus to fill evenly by the U Tube effect

[0025] According to a further aspect of the invention the well can have permanent metal to metal seals placed at any desired depth in the well, in any number of annulus, provided the annulus can be penetrated.

[0026] According to a further aspect of the invention, when the heat source is removed, as the steel tubulars cools they slightly contract, whereas as the bismuth cools it expands, thereby energising the metal to metal seal.

[0027] According to a further aspect of the invention additional holes maybe punched into the tubing above the bismuth metal to metal seal and cement circulated and positioned above the metal-to-metal seal inside the tubing and annulus A and annulus B

[0028] According to a further aspect of the invention a disposable chock (flow restrictor) is deployed inside the tubing before cement is circulated thus ensuring the controlled placement of the cement and eliminating U tubing which can have a serious detrimental effect of the final cement slurry placement

[0029] According to a further aspect of the invention the disposable choke can be gravity deployed

[0030] According to a further aspect of the invention the disposable choke could be deployed on a metal clad fibre optic cable.

[0031] According to a further aspect of the invention the choke area is formed by the OD of the tool and ID of the tubing in the well

[0032] According to a further aspect of the invention the disposable fibre optic cable could provide distributed sensor feedback of the cement process According to a further aspect of the invention the disposable fibre optic cable could provide distributed temperature feedback of the cement process

[0033] According to a further aspect of the invention in combination with disposable acoustic transmitters the disposable fibre optic cable could provide distributed acoustic feedback of the cement process, providing both cement bond and cement density measurements

[0034] According to a further aspect of the invention at least one disposable battery powered acoustic transmitters could be combined with the metal clad fibre

[0035] According to a further aspect of the invention the tool housing containing the acoustic transmitter could include a heater and bismuth to make a metal-to- metal seal inside the housing once the cement has set

[0036] According to a further aspect of the invention the fibre optic cable could have a shear release mechanism to enable the fibre optic cable above the cement to be retrieved back to surface, so only a small portion is consumed, and the rest can be used for a future operation

[0037] The following is a more detailed description of an embodiment according to invention by reference to the following drawings in which:

[0038] Figure 1 is a section side view of a well with the 1st operation of a metal-to- metal seal placed inside the tubing and first annulus outside the tubing.

[0039] Figure 2. is a section side view of a well with the 2nd operation of a metal to metal seal placed inside the tubing and first annulus outside the tubing

[0040] Figure 3 is a section side view of a well with the 3rd step of the operation of a metal-to-metal seal placed inside the tubing and first annulus outside the tubing. Figure 4 is a section side view of a well with the 4th step of the operation of a metal-to-metal seal placed inside the tubing and first annulus outside the tubing.

[0041] Figure 5 is a section side view of a well with the final step of the operation of a metal-to-metal seal placed inside the tubing and first annulus outside the tubing.

[0042] Figure 6 is a section side view of a well with the 1st operation of a metal-to- metal seal placed inside the tubing and first and second annulus outside the tubing.

[0043] Figure 7. is a section side view of a well with the 2nd operation of a metal to metal seal placed inside the tubing and first and second annulus outside the tubing.

[0044] Figure 8 is a section side view of a well with the 3rd step of the operation of a metal-to-metal seal placed inside the tubing and first and second annulus outside the tubing.

[0045] Figure 9 is a section side view of a well with the 4th step of the operation of a metal-to-metal seal placed inside the tubing and first and second annulus outside the tubing.

[0046] Figure 10 is a section side view of a well with the 5th step of the operation of a metal-to-metal seal placed inside the tubing and first and second annulus outside the tubing.

[0047] Figure 11 is a section side view of a well with the final operation of a metal- to-metal seal placed inside the tubing and first and second annulus outside the tubing.

[0048] Figure 12 is a section side view of a well describing a 2ndembodiment of the invention with the 1st operation of a metal-to-metal seal placed inside the tubing above the reservoir. Figure 13 is a section side view of a well shown in figure 12 with the 2nd operation of a metal-to-metal seal placed inside the tubing above the reservoir.

[0049] Figure 14 is a section side view of a well shown in figure 13 with the 3rd operation of a metal-to-metal seal placed inside the tubing above the reservoir and the conveyance tool being pulled out of the hole

[0050] Figure 15 is a section side view of a well with the 1st operation (setting a bridge plug) of a metal-to-metal seal placed inside the tubing and annulus A

[0051] Figure 16. is a section side view of a well with the 2nd operation (puncturing the tubing ) of a metal to metal seal placed inside the tubing and annulus A

[0052] Figure 17 is a section side view of a well with the 3rd step of the operation (placing molten bismuth in the tubing and annulus A) of a metal-to-metal seal placed inside the tubing and annulus A.

[0053] Figure 18 is a section side view of a well with the 4th step of the operation (placing molten bismuth in the tubing and annulus A) of a metal-to-metal seal placed inside the tubing and first annulus outside the tubing.

[0054] Figure 19 is a section side view of a well with the 5th step of the operation (placing molten bismuth in the tubing and annulus A) of a metal-to-metal seal placed inside the tubing and first annulus outside the tubing.

[0055] Figure 20 is a section side view of a well with the 6th step of the operation (perforating above the bismuth) of a metal-to-metal seal placed inside the tubing and first annulus outside the tubing.

[0056] Figure 21 is a section side view of a well with the 7th step of the operation (installing a disposable choke and disposable sensor system to verify the cement plug placement) of a metal-to-metal seal placed inside the tubing and first annulus outside the tubing. Figure 22 is a section side view of the well with detail A of figure 21, showing the disposable choke and disposable acoustic transmitter

[0057] Figure 23 is a section YY plan view from figure 22 showing the flow choke area created between the tubing ID and the disposable choke OD

[0058] Figure 24 is a section XX plan view from figure 22 showing the flow nonchoke area created between the tubing ID and the disposable choke OD

[0059] Figure 25 is a calculation of the pressure drop for a single choke are for a typical cement density and placement flow rate and the pressure drop if 30 chokes are used

[0060] Figure 26 is a section side view of the well with detail B of figure 21, showing the disposable fibre optic cable and disposable battery powered acoustic transmitter before cementing

[0061] Figure 27 is a section side view of the well with detail B of figure 21, showing the disposable fibre optic cable and disposable acoustic transmitter after cementing and the internals of the tool sealed with molten bismuth

[0062] Figure 28 is a section side view of a well with the final step of the operation (cement placed on top of the bismuth plug with a disposable sensing system set in the cement) of a metal-to-metal seal placed inside the tubing and first annulus outside the tubing.

[0063] Figure 29 is a section side view of a well with the 1st operation (set bridge plug) of a 3rdtype of hybrid metal-to-metal and cement seal placed inside the tubing and annulus A and annulus B

[0064] Figure 30 is a section side view of a well with the 2nd operation (perforate the tubing and casing) of a 3rdtype of hybrid metal-to-metal and cement seal placed inside the tubing and annulus A and annulus B Figure 31 is a section side view of a well with the 3rd operation (deploy heater and bismuth and place molten bismuth in tubing and annulus a and b) of a 3rdtype of hybrid metal-to-metal and cement seal placed inside the tubing and annulus A and annulus B

[0065] Figure 32 is a similar view to figure 31 showing a further sequence in the molten bismuth placement of the 3rdoperation.

[0066] Figure 33 is a similar view to figure 32 showing a further sequence in the molten bismuth placement of the 3rdoperation.

[0067] Figure 34 is a similar view to figure 33 showing the molten bismuth placement of the 3rdoperation completed

[0068] Figure 35 is a section side view of a well with the 4th operation (perforating above the bismuth plug and placing a disposable choke and sensor array in the tubing to monitor and verify the cement placement) of a 3rdtype of hybrid metal-to-metal and cement seal placed inside the tubing and annulus A and annulus B

[0069] Figure 36 is the completion of the 4thoperation, cement plug placement completed in tubing and annulus A and B, and the fibre optic cable disconnected from the disposable portion left in the cement plug.

[0070] Referring to figure 1 to 5 there is shown a typical platform type well arrangement, with a surface casing 1 combining as a riser 2 to the wellhead deck 3 of the platform 4. This is cemented in place from its shoe 5 to the mud line 6.

[0071] Inside this is an intermediate size casing 7 which goes from the wellhead to just above the reservoir 8, in most cases the liner would be cemented across the reservoir, however in this example the production tubing 9 has been cemented 10 across the reservoir; the abandonment method described herein is applicable to both instances. This has then been perforated 11 to enable the reservoir fluids to flow to surface via the production tubing. At the end of commercial production, it is necessary to abandon the well, traditionally this has required all the tubing and casing to be removed from the well to enable long cement plugs to be placed inside the resulting open hole. This is extremely expensive and time consuming.

[0072] The method shown will seal the well while requiring no material to be removed from the well

[0073] The first seal 400 is required above the reservoir and is achieved using a tool string and method described in complete detail in PCT / GB2021 / 051434

[0074] The next operations are the main focus for this application

[0075] Operation 1 is to run a bridge plug 30 to provide a base for the subsequent operations

[0076] Operation 2 is to run a tubing hole puncturing tool 29 to make holes 31 the tubing 9 above the bridge plug 30. Note that operation 1 and 2 could be combined into a single operation. Note that this tool and its operation is described in more detail in PCT / GB2021 / 051431

[0077] Operation 3 is to run a heating tool 28 to above the bridge plug. This heating tool could be thermite based or electrical heat element Note that this tool and its operation is described in more detail in GB 2017031.2

[0078] Operation 4 is to deposit bismuth beads 32 [the bismuth in the figures is bit difficult to see - might be better if possible to illustrate it in a more visible way, perhaps with heavier hatching] onto the heating element from the housing above the heater, as the bismuth melts it flows out of the perforations 31 and on the low side of the perforations below the heating tool, the bismuth quickly solidifies 33 eventually forming a solid base at the low side of the perforations As the upper side of the tubing above the perforations is also adjacent to the heating tool the bismuth is still above its melting point, and the bismuth has approximately ten times the specific gravity of the fluid in the well, the bismuth flows through the perforations 31 into the annulus 35 to form an equal column of bismuth both inside the tubing 34 and in the annulus 35

[0079] When the heating tool is removed, the bismuth balances while it is still liquid the result is a solid plug of bismuth, both inside the tubing and inside the annulus of equal height. As it cools and returns to a solid state it expands by approx. 3% and thus squeezes between the casing 7 and the outside of the tubing 9, and the bismuth inside the tubing exerts an outward force on the internal surface of the tubing.

[0080] Referring to figures 6 to 11 there is shown a sequence to seal the tubing ID 37, annulus A 38 and annulus B 39.

[0081] Operation 1 is to run a bridge plug 40 to provide a base for the subsequent operations.

[0082] Operation 2 is to run a tubing hole puncturing tool 41 to make holes 42 in the tubing 9 and the casing 43 outside it above the bridge plug 40. Note that operation 1 and 2 could be combined into a single operation. Note that this tool and its operation is described in more detail in GB2015346.6, where it is necessary to puncture the casing beyond the tubing

[0083] Operation 3 is to run a heating tool 44 to above the bridge plug. This heating tool could be thermite based or electrical heat element, or a combination

[0084] Operation 4 is to deposit bismuth beads 45 onto the heating element 44, as the bismuth melts it flows out of the perforations 42 and on the low side of the perforations, the bismuth quickly solidifies 46 eventually forming a solid base in the annulus A 47. As more bismuth displaces the fluid in the annulus, more heat is transferred to the casing 48 outside it. As the heating is transferred to the bismuth in the first annulus A its flows into annulus B 49 where it quickly solidifies and forms a solid base 50 on the low side of the perforations for the liquid bismuth to be supported on top of it.

[0085] The liquid bismuth is between approximately 7-10 times the density of the liquid in annulus A and B. and provides the hydrostatic force to displace the liquid bismuth into the annulus A and B, as more bismuth flows into the annulus A and B more heat is transferred to the annulus A and B, resulting in easier flow of the bismuth into both annuli, resulting in the top level of the molten bismuth approximately equalising in height across the tubing ID and annuli in a similar way to the previously described steps.

[0086] The result is a solid plug of bismuth, both inside the tubing 52 and inside the annulus A 53 and the Annulus B 54. As it cools and returns to a solid state it expands by approx. 3% and thus squeezes between the surface casing 1 and the intermediate casing 7, and intermediate casing 7 and the outside of the tubing 9, and the bismuth inside the tubing exerts an outward force on the internal surface of the tubing 9.

[0087] Referring to figure 12 to 14 there is shown a typical platform type well arrangement, with a surface casing 101 combining as a riser 102 to the wellhead deck 103 of the platform 104. This is cemented in place from its shoe 105 to the mud line 106.

[0088] Inside this is an intermediate size casing 107 which goes from the wellhead to just above the reservoir 108, in most cases the liner would be cemented across the reservoir, however in this example the production tubing 109 has been cemented 110 across the reservoir. This has then been perforated 111 to enable the reservoir fluids to flow to surface via the production tubing.

[0089] As previously discussed, at the end of commercial production, it is necessary to abandon the well, traditionally this has required all the tubing and casing to be removed from the well to enable long cement plugs to be placed inside the resulting open hole. This is extremely expensive and time consuming. The method shown will seal the well while requiring no material to be removed from the well

[0090] Operation 1 is to run a bridge plug 120 to provide a base for the subsequent operations.

[0091] Operation 2 is to run a heating tool 121 on a wireline 170 to above the bridge plug. This heating tool could be thermite based or electrical heat element, or a combination Note that this tool and its operation is described in more detail in PCT / GB2021 / 051434

[0092] Operation 3 is to deposit bismuth beads 122 onto the heating element, as the bismuth melts it forms a molten mass around the heating tool. Temperature sensors in the heating tool will provide feedback that the bismuth is at the uniform temperature and the heating tool can be removed 123 back to surface. On cool down the bismuth solidifies and forms a solid metal to metal seal 124 above the bridge plug

[0093] Referring to figures 15 to 28;

[0094] Operation 1 is to run a bridge plug 130 to provide a base for the subsequent operations

[0095] Operation 2 is to run a tubing hole puncturing tool 129 to make holes 131 the tubing 109 above the bridge plug 130

[0096] Operation 3 is to run a heating tool 128 to above the bridge plug. This heating tool could be thermite based or electrical heat element, or a combination of both.

[0097] Operation 4 is to deposit bismuth beads 132 onto the heating element, as the bismuth melts it flows out of the perforations and on the low side of the perforations, below the heating element the bismuth quickly solidifies 133 eventually forming a base 172. As the upper side of the perforations is adjacent to the heating tool the bismuth is still above its melting point, the bismuth with approximately 10 times the specific gravity of the fluid in the well, flows through the holes 131 to form an equal column of bismuth both inside the tubing 134 and in the annulus 135

[0098] The bismuth below the perforation 172 is sufficient to form a base but does not have a good pressure containment quality. The bismuth above the perforation and which was a fully molten mass forms a very high-quality metal to metal seal and hence an excellent pressure barrier (134,135).

[0099] The result is a solid plug of bismuth, both inside the tubing and inside the annulus. As it cools and returns to a solid state it expands by approx. 3% and thus squeezes between the casing 107 and the outside of the tubing 109, and the bismuth inside the tubing exerts an outward force on the internal surface of the tubing

[0100] Operation 5 is to is to run a tubing hole puncturing tool 173 to make holes 300 in the tubing 109 above the bismuth plug 134 inside the tubing.

[0101] Operation 6 is to install a disposable choke 200 on a metal clad fibre optic cable 201, the fibre optic cable provides real time distributed sensing in its simplest form distributed temperature, so will verify the cement setting process in the tubing 302 and the annulus 301 and will also accurately show the exact top of cement 303. The choke is a hollow tube 202, with the metal clad fibre attached to its nose 203. Inside the nose could also be a battery powered acoustic transmitter 204 and the fibre optic cable can also act as an acoustic receiver so it could also provide a cement bond and cement density measurement during and at the end of the cement setting process. Disposable transmitters 205 could be distributed along the metal clad fibre. The inside of the acoustic transmitter will be bismuth 210 and a nichrome wire heating element wire 304 embedded inside the bismuth, the lithium battery 211 which is used to power the acoustic transmitter 205 also after a set period of time (24-48hrs) heats up the bismuth, which melts and forms a solid barrier 212 On the outside of the choke tube 202 are discs 213, when the OD of the disc 306 is adjacent to the tubing ID 305 it provides the flow restriction area 206, to ensure the flow path does not get plugged, it is relatively speaking quite a large area 214, in this case 2sq inches (13 cm2), which generates about 20psi pressure drop at the flow rate and density of a typical plug placement, by using many of the choke discs 213 a very significant back pressure is generated which ensures the controlled placement of the cement slurry 208 described below.

[0102] Operation 6 is to circulate cement down the tubing, and into the annulus to form a balanced cement plug 136 inside the tubing and annulus 135.

[0103] Referring to figures 29 to 36 there is shown a sequence to seal, the tubing ID 137, annulus A 138 and annulus B 139.

[0104] Operation 1 is to run a bridge plug 140 to provide a base for the subsequent operations.

[0105] Operation 2 is to run a tubing hole puncturing tool 141 to make holes 142 in the tubing 119 and the casing 143 outside it above the bridge plug 140

[0106] Operation 3 is to run a heating tool 144 to above the bridge plug. This heating tool could be thermite based or electrical heat element

[0107] Operation 4 is to deposit bismuth beads 145 onto the heating element, as the bismuth melts it flows out of the perforations 142 and on the low side of the perforations, the bismuth quickly solidifies 146 eventually forming a solid base in the annulus A 147. As more bismuth displaces the fluid in the annulus, more heat is transferred to the casing 148 outside it. As the heating is transferred to the bismuth in the first annulus A its flows into annulus B 149 where it quickly solidifies and forms a solid base 150 for the liquid bismuth to be supported on. The liquid bismuth is between 7-10 times the density of the liquid in annulus A and B. The column in the tubing 151 provides the hydrostatic force to displace the liquid bismuth in the annulus A and B, as more bismuth flows into the annulus A and B more heat is transferred to the annulus A and B, resulting in easier flow of the bismuth into both annuli.

[0108] The result is a solid plug of bismuth, both inside the tubing 152 and inside the annulus A 153 and the annulus B 154. As it cools and returns to a solid state it expands by approx. 3% and thus squeezes between the surface casing 101 and the intermediate casing 107, and intermediate casing 107 and the outside of the tubing 109, and the bismuth inside the tubing exerts an outward force on the internal surface of the tubing 109.

[0109] Operation 5 is to run a tubing hole puncturing tool to make holes 160 in the tubing 109 and the casing 143 outside it above the bismuth plug set in operation 4.

[0110] A disposable choke 200 is deployed on a section of disposable metal clad fibre optic cable 201 with also disposable distributed battery powered acoustic transmitters 204, as described earlier are to ensure the controlled placement of cement slurry and then to verify the quality of cement and cement setting process by a combination of temperature and acoustic measurements.

[0111] Then cement slurry can be circulated down the tubing into the annulus A and annulus B to form a balanced plug 161. Alternatively, it could be circulated down one of the annuli to minimise the effect of U tubing if no choke is used.

[0112] After monitoring the cement temperature, at a suitable time after the cement operation, the disposable portion of the metal clad fibre optic cable 162 can be left in the well, and a shear release 163 can ensure the reliable separation of the metal clad fibre optic cable, and the recovered metal clad fibre 164 can be reused on a future job.

Claims

1. A method of abandoning a well, the well comprising at least a length of tubing, and a first annulus outside the tubing, comprising the steps of:installing a bridge plug within the tubing;puncturing a hole or holes in the tubing, the holes in the tubing giving access to the first annulus immediately outside the tubing;heating the inside of the tubing;depositing bismuth in proximity to the region inside the tubing which is heated,such that the bismuth melts, the quantity of bismuth being sufficient that a first portion of the bismuth remains in the tubing above the bridge plug, while a second portion of the bismuth flows through the holes in the tubing into the first annulus to the non-heated section allowing the bismuth to initially cool and solidify on the inner surface of the annulus to form a non-uniform base on the low side of the tubing, and thereafter accumulates to form a continuous solid plug in the annuluswherein there is included a further step of circulating cement into the tubing and the first annulus above the solidified bismuth, such that the cement forms a further plug above the bismuth plug.

2. A method of abandoning a well according to claim 1, wherein there is included a further step of puncturing one or more additional holes in the tubing at a position above the solidified bismuth to allow fluid communication between the tubing and the first annulus at a location above the plug.

3. A method according to either previous claim wherein the well further comprises a second tube concentric with the length of tubing, and a further annulus outside the second tube, and including the step ofpuncturing a hole or holes in the second tube, the holes in the tubing giving access to the further annulus immediately outside the second tubethe quantity of bismuth being sufficient that a third portion of bismuth flows through the holes in the second tube into the further annulus.

4. A method of abandoning a well according to any previous claim, wherein the holes are punctured by a method selected from one of the following mechanical means.explosive means.laser meansthermite plasma means.

5. A method of abandoning a well according to any previous claim, wherein the inside of the tubing is heated using a source selected from one of the following:thermite heat sourceelectrical heat trace heat source6. A method of abandoning a well according to any previous claim, wherein the bismuth is deposited in the forms of bismuth beads deposited on the heat source.

7. A method of abandoning a well according to claim 6, wherein the bismuth beads are conveyed in a container above the heat source.

8. A method of abandoning a well according to claim 6, wherein the bismuth beads are deposited from surface using gravity9. A method of abandoning a well according to any of claims 1 to 5, wherein the bismuth is cast onto the heating element and conveyed into the well by the heating element.

10. A method of abandoning a well according to any previous claim, wherein there is included the step ofdeploying a disposable choke inside the tubing before cement is circulated to restrict the flow of cement to ensuring the controlled placement of the cement.

11. A method of abandoning a well according to claim 10, wherein the disposable choke is deployed by a method selected from one of the following gravity deployed disposable choke is deployed on a metal clad fibre optic cable.

12. A method of abandoning a well according to any of claims 10 or 11, wherein the choke area is formed by the OD of the choke and ID of the tubing.

13. A method of abandoning a well according to any of claims 10 to 12 wherein the disposable choke is deployed on a metal clad fibre optic cable provides distributed sensor feedback of the cement process.

14. A method of abandoning a well according to any of claims 10 to 13 wherein at least one disposable battery powered acoustic transmitters is combined with the metal clad fibre optic cable.

15. A method of abandoning a well according to claim 14 wherein the disposable fibre optic cable in combination with disposable acoustic transmitters the disposable fibre optic cable provides distributed acoustic feedback of the cement process, providing both cement bond and cement density measurements.

16. A method of abandoning a well according to any of claims 14 to 15 wherein a tool housing containing the acoustic transmitter includes a heater and bismuth to make a metal-to-metal seal inside the housing once the cement has set.

17. A method of abandoning a well according to any of claims 10 to 16 wherein the fibre optic cable has a shear release mechanism to enable the fibre optic cable above the cement to be retrieved back to surface.

18. A method of abandoning a well according to any of claims 10 to 17, wherein the choke comprising a hollow tube having discs disposed long the length of the inside of the hollow tube, such that the tube allows a throughflow which is restricted by the discs, the hollow tube being suspended by a fibre optic cable terminating at the lower end of the hollow tube, the fibre optic cable including sensors.5 19. A method of abandoning a well according to claim 18 wherein the sensorsinclude acoustic sensors, and acoustic transmitters are included in the choke.

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