WELL TOOL DEVICE AND METHOD OF FORMING A PERMANENT WELL BARRIER, CONFIGURED TO GENERATE A FORCED FLOW OF MOLTEN MASS

Abstract

A well tool device for forming a permanent well barrier includes a housing having a circular cross-section and a longitudinal extension; a pyrotechnic mixture provided in the housing; a flow generating device provided in the housing; and a motor for driving the flow generating device. After ignition, the pyrotechnic mixture turns into a molten mass; and the flow generating device is configured to generate a forced flow of the molten mass. A method for forming a permanent well barrier using the well tool device includes installing the well tool device in a well; and igniting the pyrotechnic mixture. The pyrotechnic mixture turns into a molten mass upon ignition. The method further includes starting the motor; and generating a forced flow of molten mass by the flow generating device.

Claims

1. A well tool device for forming a permanent well barrier, wherein the well tool device comprises: a housing having a circular cross-section and a longitudinal extension; a pyrotechnic mixture provided in the housing; a flow generating device provided in the housing; a motor for driving the flow generating device; wherein, after ignition, the pyrotechnic mixture turns into a molten mass; and wherein the flow generating device is configured to generate a forced flow of the molten mass.

2. The well tool device according to claim 1, wherein the flow generating device is a foldable impeller, a closed impeller, a single-suction impeller, a dual-suction impeller, a paddle impeller, a propeller, a whisk, a ribbon impeller, an anchor impeller, a turbine type impeller, or combinations thereof.

3. The well tool device according to claim 1, wherein the flow generating device is a foldable impeller with a plurality of foldable blades; wherein rotation of the flow generating device cause the blades to unfold and the plurality of blades rotates in a circular cross-section which extends beyond the circular cross-section of the housing when the blades are fully unfolded.

4. The well tool device according to claim 3, wherein the foldable blades are provided with tips adapted to scrape any contacting surface while maintaining their structural integrity.

5. The well tool device according to claim 1, wherein the flow generating device is made from a material with a higher melting point then the temperature of the molten mass.

6. The well tool device according to claim 1, wherein the flow generating device is adapted to generate a forced flow of fluids directed in a radial direction from a center axis of the housing.

7. The well tool device according to claim 1, wherein the well tool device comprises: an energy source for powering the motor.

8. The well tool device according to claim 1, wherein the flow generating device comprises: a shaft for connecting the flow generating device to the motor; wherein the shaft is concentric with the housing.

9. The well tool device according to claim 1, wherein the motor is arranged below the flow generating device when the well tool device is installed in a well.

10. The well tool device according to claim 1, wherein the well tool device comprises: a plurality of flow generating devices; wherein the flow generating devices are axially arranged relative each other on the same shaft.

11. The well tool device according to claim 1, wherein the pyrotechnic mixture comprises thermite.

12. A method for forming a permanent well barrier using a well tool device, the well tool device comprising: a housing having a circular cross-section and a longitudinal extension; a pyrotechnic mixture provided in the housing; a flow generating device provided in the housing; a motor for driving the flow generating device; wherein the flow generating device is configured to generate a forced flow of fluids within the housing; wherein the method comprises the steps of: installing the well tool device in a well; igniting the pyrotechnic mixture, the pyrotechnic mixture turns into a molten mass upon ignition; starting the motor; and generating a forced flow of molten mass by means of the flow generating device.

13. The method according to claim 12, wherein the method comprises: directing the forced flow of fluids in a radial direction of the housing.

14. The method according to claim 12, wherein the flow generating device comprises: a foldable impeller with a plurality of foldable blades; wherein the method comprises: unfolding the foldable blades of the foldable impeller by means of increasing the rotational speed of the flow generating device.

15. The method according to claim 14, wherein the foldable blades are provided with reinforced tips adapted to scrape any contacting surface while maintain their structural integrity; wherein the method comprises: scraping the surface of a surrounding solid-state material by means of the tips of the foldable impeller blades.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0110] The invention will now be described with reference to the exemplifying non-limiting embodiments shown in the accompanying drawings, wherein:

[0111] FIG. 1 shows a cross-section of a well tool device for forming a permanent well barrier according to an embodiment of the invention;

[0112] FIG. 2 shows a cross-section of a well tool device for forming a permanent well barrier with some additional features compared to the well tool device 10 disclosed in FIG. 1;

[0113] FIG. 3 shows a cross-section of a well tool device for forming a permanent well barrier which is similar to the embodiment of FIG. 1 except that the flow generating device is replaced with a flow generating device of a different size;

[0114] FIG. 4 shows a cross-section of a well tool device for forming a permanent well barrier, similar to the embodiment of FIG. 1 except that the well tool device has a plurality of flow generating devices;

[0115] FIG. 5 shows a cross-section of a well tool device for forming a permanent well barrier, the well tool device is similar to the embodiment of FIG. 1 except that the motor and the energy source are differently arranged;

[0116] FIG. 6 shows a cross-section of a well tool device for forming a permanent well barrier, the well tool device is similar to the embodiment of FIG. 1 except that the energy source is differently arranged and that it has an alternative embodiment of the shaft;

[0117] FIG. 7 shows a cross-section of a well tool device for forming a permanent well barrier, the well tool device is similar to the embodiment of FIG. 1 except that it has a support device;

[0118] FIG. 8 shows a cross-section of a well tool device for forming a permanent well barrier, the well tool device is similar to the embodiment of FIG. 7 except it has a shorter shaft, i.e. only one endpoint of the shaft 61 is arranged in the housing 20;

[0119] FIG. 9 shows a cross-section of a well tool device for forming a permanent well barrier, the well tool device is similar to the embodiment of FIG. 7 except it has a double set of energy source, motor, shaft and flow generating device;

[0120] FIG. 10 shows a cross-section of a well tool device for forming a permanent well barrier, the well tool device is similar to the embodiment of FIG. 1 wherein the flow generating device is of the mechanically expandable type;

[0121] FIG. 11 shows a cross-section of a melted well tool device for forming a permanent well barrier after melting of the pyrotechnic mixture and any surrounding materials; and

[0122] FIG. 12 shows the situation in a well after ignition of the pyrotechnic mixture.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

[0123] FIG. 1 shows a cross-section of a well tool device 10 for forming a permanent well barrier. The well tool device 10 has a housing 20 defining a compartment 30, in which compartment 30 a pyrotechnic mixture 40 is provided.

[0124] The housing 20 typically has a circular cross-section and a longitudinal extension with a length L. The cross-section of the housing 20 may alternatively have other shapes, e.g. polygonal. The outer diameter of the well tool device 10 is dimensioned to fit in the inner diameter of the well into which the well tool device 10 shall be installed. The longitudinal extension of the housing 20 may have a length L from 5 meters to 20 meters depending on factors such as required amount of pyrotechnic mixture 40 and size of the required permanent well barrier. The cross-section of the well tool device 10 may be sized in accordance with the tubing and or well in which it is intended to be installed.

[0125] A flow generating device 60 may be arranged in the housing 20. The flow generating device 60 may be adapted to generate a forced flow of the pyrotechnic mixture 40 after it has turned into a molten mass when ignited. The flow generating device 60 may be adapted to generate a forced flow of the molten mass created by the heat generating process. In most cases a forced flow in the radial direction from a center axis of the housing is desired; however, an axially directed flow may also be generated.

[0126] The flow generating device 60 may be made of a material capable of withstanding the temperature reached by the heat generating process, e.g. a refractory metal such as tungsten.

[0127] The flow generating device 60 is typically rotated around an axis (e.g. a center axis of the well tool device 10) to generate a flow of fluids. The flow generating device 60 may be a foldable impeller, a closed impeller, a single-suction impeller, a dual-suction impeller, a paddle impeller, a propeller, a whisk, a ribbon impeller, an anchor impeller, a turbine type impeller, or combinations thereof or any other device suitable for generating a laminar or turbulent flow of liquids, such as a molten mass, either radially or axially. The design of such devices is common general knowledge for a person skilled in the art and will thus not be discussed in detail.

[0128] The flow generating device 60 may be arranged closer to the bottom of the compartment 30 than to the top of the compartment 30 when the well tool device 10 is installed in a well. The clearance between the flow generating device 60 and the bottom of the compartment 30 may be 0.3-1.0 meters. The flow generating device 60 is typically arranged in the lower half of the compartment 30.

[0129] A motor 70 may be arranged in the well tool device 10 to drive the flow generating device 60. In the embodiment of FIG. 1, the motor 70 is arranged below the flow generating device 60. The motor 70 may be arranged inside the compartment 30 or arranged above or below as an attachment to the housing 20. The motor 70 may be electrically operated.

[0130] An energy source 75 adapted to power the motor 70 may be arranged adjacent to the motor 70, either inside the compartment 30 or as an attachment to the housing 20. The energy source 75 may be a battery.

[0131] The flow generating device 60 may be provided with a shaft 61. The shaft 61 may be adapted to rotate the flow generating device 60. The shaft 61 may be axially arranged in the well tool device 10 to connect with the motor 70, e.g. arranged concentric with the housing 20. The shaft 61 is preferably pivotally arranged in at least two points of the well tool device 10, e.g. bushings arranged in the top and the bottom of the well tool device 10. The shaft 61 may be connected to the flow generating device 60 by means of a keyed joint. Alternatively, the shaft 61 may be connected to the flow generating device 60 by means of welding. Alternatively, the shaft 61 and the flow generating device 60 may be machined as one item.

[0132] The shaft 61 is preferably made of a material capable of withstanding the temperature provided by the heat generating process, e.g. a refractory metal such as tungsten.

[0133] After installing one or several well tool devices 10 in a well, the pyrotechnic mixture 40 can be ignited. The pyrotechnic mixture 40 turns into a molten mass after ignition. The motor 70 may start rotating the flow generating device 60 simultaneously with or after the ignition of the pyrotechnic mixture 40. This may be achieved by means of a timer adapted to start the motor 70 at a given time relative to ignition of the pyrotechnic mixture 40. This may also be achieved with a triggering mechanism by means of a temperature sensor. The flow generating device 60 can then in turn create a forced flow of the molten mass. With the appropriate flow generating device 60, the forced flow of the molten mass can be directed in a radial direction from a center line of the housing 20.

[0134] FIG. 2 shows a cross-section of a well tool device 10 for forming a permanent well barrier with some additional features compared to the well tool device 10 disclosed in FIG. 1.

[0135] The well tool device 10 in FIG. 2 is provided with an ignition head 50 arranged inside the compartment 30. This ignition head 50 is suitable for igniting the pyrotechnic mixture 40. The ignition head 50 may be powered by the energy source 75.

[0136] If several well tool devices 10 are run as a stack or adjacently installed in the well, only one of the well tool devices 10 require an ignition head 50. The pyrotechnic mixture in the first well tool device 10 is ignited by the ignition head 50, this reaction will in turn ignite the surrounding well tool devices 10. The well tool device 10 provided with an ignition head 50 is preferably installed in the well below any other well tool devices 10 not provided with an ignition head 50. All embodiments of the well tool device 10 may or may not be provided with an ignition head 50.

[0137] A heat insulating device 80 may be arranged to isolate the motor 70 from the compartment 30. The heat insulating device 80 is preferably made of a material which can withstand the expected temperature of the heat generating process, e.g. a refractory material such as graphite. A heat insulating device 80 may be arranged as the bottom of the compartment 30 when the well tool device 10 is installed in a well, the top of the compartment 30 when the well tool device 10 is installed in a well, as a partition wall in the compartment 30 or any combinations thereof.

[0138] During the heat generating process the molten mass will melt and mix with any surrounding material creating a molten mass and thus extend in a radial direction from the center axis of the housing. To improve this radial extension of the molten mass, the flow generating device 60 may be adapted to expand radially. By being radially expandable, the flow generating device 60 will improve the supply of heat from the molten mass to these radially extended areas.

[0139] The flow generating device 60 may be a foldable impeller which expands in a radial direction from the center axis of the housing in response to a speed of rotation, i.e. mechanically expandable. A flow generating device 60 in the form of a foldable impeller typically has hinged blades which folds out as the impeller rotates. The length of such blades is preferably dimensioned based on the desired radial extension of the molten mass, and thus the size of the permanent well barrier.

[0140] As the molten mass gradually extends, the blades of the flow generating device 60 may gradually expand. Before the molten mass has reached the intended radial extension, the foldable blades of the flow generating device 60 may scrape the surface of surrounding materials. The flow generating device 60 may therefore be provided with durable tips adapted to scrape any contacting surface while maintaining their structural integrity. Such durable tips 62 will improve the radial extension of the molten mass. The durable tips 62 may also be adapted to tear off parts from the surrounding surfaces on which they scrape, e.g. by being provided with a rough surface, spikes, sharp edges or the like.

[0141] FIG. 3 shows a cross-section of a well tool device 10 for forming a permanent well barrier which is similar to the embodiment of FIG. 1 except that the flow generating device 60 is replaced with a flow generating device 60 of a different size. This embodiment of the well tool device 10 may additionally also comprise any of the features of the embodiment of FIG. 2.

[0142] The flow generating device 60 of FIG. 3 has an axial length extending at least half the axial length of the compartment 30. Whereas the flow generating device 60 of FIG. 1 has an axial length extending less than half the axial length of the compartment 30.

[0143] FIG. 4 shows a cross-section of a well tool device 10 for forming a permanent well barrier, similar to the embodiment of FIG. 1 except that the well tool device has a plurality of flow generating devices 60. This embodiment of the well tool device 10 may additionally also comprise any of the features of the embodiment of FIG. 2.

[0144] The flow generating device 10 of FIG. 4 has three flow generating devices 60. A person skilled in the art would understand that any number of flow generating devices 60 may be arranged in the compartment 30 of the well tool device 10. The plurality of flow generating devices 60 are disclosed arranged on the same shaft 61, however they may also be arranged on parallel shafts. The plurality of flow generating devices 60 may be of the same type or of different types. The plurality of flow generating devices 60 may be of the same size or of different sizes.

[0145] FIG. 5 shows a cross-section of a well tool device 10 for forming a permanent well barrier, the well tool device is similar to the embodiment of FIG. 1 except that the motor 70 and the energy source 75 are differently arranged. This embodiment of the well tool device 10 may additionally also comprise any of the features of the embodiments of FIGS. 2, 3 and 4.

[0146] In the embodiment of FIG. 5, the motor 70 is arranged above the flow generating device 60. The motor 70 may be arranged inside the compartment 30. The motor 70 may also be arranged above or below as an attachment to the housing 20.

[0147] The energy source 75 may be arranged adjacent to the motor 70, either inside the compartment 30 or above or below as an attachment to the housing 20. The energy source 75 may also be located topside. The energy source 75 may be a battery, a generator or a power grid.

[0148] FIG. 6 shows a cross-section of a well tool device 10 for forming a permanent well barrier, the well tool device 10 is similar to the embodiment of FIG. 1 except that the energy source 75 is differently arranged and that it has an alternative embodiment of the shaft 61. This embodiment of the well tool device 10 may additionally also comprise any of the features of the embodiment of FIGS. 2, 3 and 4.

[0149] In the embodiment of FIG. 6, the shaft 61 has a concentric through hole, whereas the shaft 61 of the other embodiments are solid. The through hole in the shaft 61 enables communication between the two sides of the housing 20 to which the shaft 61 is arranged.

[0150] In the embodiment of FIG. 6, the motor 70 and the energy source 75 are arranged on opposite sides of the housing 20. The motor 70 is connected to the energy source 75 via a power cord arranged through the through hole of the shaft 61. This embodiment provides the possibility of arranging the motor 70 below the flow generating device 60 when the well tool device 10 is installed in a well, while arranging the energy source 75 topside.

[0151] FIG. 7 shows a cross-section of a well tool device 10 for forming a permanent well barrier, the well tool device 10 is similar to the embodiment of FIG. 1, except that it has a support device 63. The support device 63 is arranged in the compartment 30 of the well tool device 10.

[0152] The support device 63 may provide a bushing device concentric with a compartment 30 of circular cross-section. The support device may comprise spokes, beams, or similar arranging the support device to the housing 20. The support device 62 may be made of the same material as the flow generating device 60 or any other material suitable for withstanding the temperature of the molten mass.

[0153] The bushing device of the support device 63 may have a through hole adapted to house a shaft 61 which endpoints are arranged outside of the bushing device. One or several flow generating devices 60 may be arranged on one or both sides of the support device 63.

[0154] The support device 63 may be arranged at an equal distance from each endpoint.

[0155] FIG. 8 shows a cross-section of a well tool device 10 for forming a permanent well barrier, the well tool device 10 is similar to the embodiment of FIG. 7, except that the shaft 61 is shorter, i.e. only one endpoint of the shaft 61 is arranged in the housing 20.

[0156] The bushing device of the support device 63 may be adapted to house an endpoint of the shaft 61.

[0157] FIG. 9 shows a cross-section of a well tool device 10 for forming a permanent well barrier, the well tool device 10 is similar to the embodiment of FIG. 7, except that it has a double set of energy source 75, motor 70, shaft 61 and flow generating device 60.

[0158] A set of energy source 75 and motor 70 may be arranged on opposite sides of the well tool device 10. Each set of energy source 75 and motor 70 may drive one shaft 61 each.

[0159] The bushing device of the support device 63 may be adapted to house both shafts 61 which each has one endpoint arranged in the bushing device at opposite sides. The shafts 61 may be of different lengths if they can be arranged such that they both have one endpoint housed in the support device 63. Alternatively, two support devices 63 may be arranged in the housing 20, each adapted to house an endpoint of a shaft 61.

[0160] FIG. 10 shows a cross-section of a well tool device 10 for forming a permanent well barrier, the well tool device 10 is similar to the embodiment of FIG. 1 wherein the flow generating device 60 is of the mechanically expandable type. This embodiment of the well tool device 10 may additionally also comprise any of the features of the embodiment of FIGS. 2, 3 and 4.

[0161] In FIG. 8, parts of the housing 20 has been melted by the molten mass. The molten mass has extended in a radial direction from the center axis of the housing beyond what was earlier defined by the compartment 30 inside the housing 20. In addition, the flow generating device 60 has expanded radially beyond what was earlier defined by the compartment 30.

[0162] The foldable flow generating device 60 may gradually expand as its speed of rotation is gradually increased. The foldable flow generating device 60 may also be rotated at a speed sufficient to fully expand the flow generating device 60 but be held back by its surroundings. In such case the foldable flow generating device 60 will gradually expand as its surroundings melt.

[0163] FIG. 11 shows a cross-section of a melted well tool device 10 for forming a permanent well barrier after melting of the pyrotechnic mixture and any surrounding materials. Only the flow generating device 60 and the shaft 61 is in a solid phase. The molten mass has completely enclosed the flow generating device 60 and the shaft 61. The flow generating device 60 and the shaft 61 may be part of the solidified permanent well barrier or they may drift out of the melt before it solidifies.

[0164] In one embodiment of the well tool device 10, the pyrotechnic mixture 40 may be adapted to reach a maximum temperature which is in the same range as the melting point of the flow generating device 60 and the shaft 61. In such an embodiment the flow generating device 60 may generate a forced flow of liquids, such as the molten mass, in a first phase before melting in a second phase.

[0165] FIG. 12 shows a cross-section of the well along a vertical plane after the ignition of the pyrotechnic mixture 40 such that proximate surrounding materials present at the position of the pyrotechnic mixture 40 have melted, e.g. tubing or liner TBG, cement CE, cap rock CR, well tool device 10, well tool device housing 20, igniting head 50, other tubulars etc. After waiting a period of time, the melted surrounding materials have solidified into a reservoir sealing barrier or permanent well barrier RSB which seals against the reservoir R in the well bore WB. The sketched area formed in the well bore WB and extending radially into the cap rock CR indicates the melted surrounding materials (i.e. the reservoir sealing barrier RSB which has been formed). The transition areas between non-affected cap rock CR and complete melted materials now forming part of the reservoir sealing barrier RSB is denoted transition zone TZ. In order for a successful reservoir sealing barrier RSB to form, it is advantageous that the bonding between the cap rock CR and the reservoir sealing barrier is satisfactory. Whether the reservoir sealing barrier seals against the reservoir, including in the transition zone, verification test such as pressure tests or sample test(s) of substances not naturally occurring above reservoir sealing barrier RSB can be performed. Such sample tests may be e.g. H2S or other gases. The pressure tests may monitor whether the pressure above the reservoir sealing barrier increases or not.

[0166] The invention is herein described in non-limiting embodiments. It should though be understood that the embodiments may be envisaged with a stack comprising two or more well tool devices. The skilled person will understand if it is desirable to set none, one, two or several permanent plugs dependent on the desired operation. Similarly, high temperature resistant elements may be provided at dedicated positions in the well to protect parts of the well or equipment lying contiguous, above or below the position where the plus is set, and may vary from zero, one, two or several, dependent on the operation.

REFERENCE LIST

[0167] 10—well tool device [0168] 20—housing [0169] 30—compartment [0170] 40—pyrotechnic mixture [0171] 50—ignition device [0172] 60—flow generating device [0173] 61—shaft [0174] 62—durable tip [0175] 63—support device [0176] 70—motor [0177] 75—energy source [0178] 80—heat insulating device [0179] CE—Cement [0180] WB—well bore [0181] CR—Cap rock [0182] L—longitudinal length of well tool device [0183] R—Reservoir [0184] RSB—reservoir sealing barrier/permanent well barrier [0185] TBG—Tubing [0186] TZ—Transition zone