Patent Description:
In <CIT> it is described a method for abandoning a well or for removing a well element. First, a heat generating mixture is lowered to the desired position in the well. Then, the heat generating mixture is ignited to start a heat generating process. The result of the heat generating process will depend on the type of, and the amount of, heat generating mixture, and may be that a well element at the desired position becomes removed or cleared, or that several concentric well elements and the material located between the well elements becomes melted and subsequently solidified to form a plug or barrier in the well.

The heat generating mixture may for example be thermite and the heat generating process will be a exothermic oxidation-reduction reaction known as a thermite reaction.

<CIT> describes a well tool and method for in situ introduction of a treatment means into a region of an annulus, comprising: an anchoring body; a perforation device for making a hole through a pipe structure; a storage chamber for the treatment means; a driving means for the treatment means; and a flow-through connection device for injection of the treatment means. The anchoring body is disposed in an anchoring module; wherein the storage chamber, the driving means and the connection device are operatively connected to an injection module; wherein the injection module can be moved axially relative to the anchoring module for moving the connection device in vicinity of the hole; and wherein the well tool comprises at least one alignment means for alignment and connection of the connection device vis-à-vis the hole.

<CIT> describes a well tool assembly comprising a setting tool and a plugging tool. The plugging tool comprises an inner mandrel device and an outer housing device, an upper sealing device, a slips device, a lower sealing device and a centralizing device connected to each other in an axial direction outside of the mandrel device. The slips device is provided axially between the upper and lower sealing devices. The centralizing device is provided below the lower sealing device or above the upper sealing device. When the centralizing device is provided below the lower sealing device, the upper sealing device, the slips device, the lower sealing device and the upper section of the centralizing device are axially displaceable downwardly and upwardly in relation to the mandrel device and the upper section of the upper sealing device is connected to the outer housing device and the lower section of the centralizing device is fixed to the inner mandrel device. When the centralizing device is provided above the upper sealing device, the centralizing device, the upper sealing device, the slips device and the upper section of the lower sealing device are axially displaceable downwardly and upwardly in relation to the mandrel device and the upper section of the centralizing device is connected to the outer housing device and the lower section of the lower sealing device is fixed to the inner mandrel device. The object of the present invention is to provide a well tool device for transporting a heat generating mixture into the well. One object is that the well tool device should be simple and cost-efficient to use.

The present invention relates to a well tool device for transporting a heat generating mixture into a well pipe, and, after ignition of the heat generating mixture (HGM), reduce molten heat generating mixture (HGM) to flow down, wherein the well tool device comprises:.

characterized in that the sealing device comprises:.

wherein the sealing element comprises a plurality of thimble-shaped elements inserted into each other to form a torus;.

The term "wedging surface" is used herein to describe a surface which, when moved towards another "wedging surface", will wedge the sealing ring radially outwards. It should be noted that both of the wedging surfaces may have an acute angle with respect to a radial plane. However, it is also possible that one of the surfaces is oriented in the radial plane while the other one of the surfaces is provided with an acute angle with respect to the radial plane.

In one aspect, the well tool device has a central longitudinal axis. A radial plane is defined as a plane perpendicular to the central longitudinal axis. The upper wedging surface and the lower wedging surface are provided radially outside of, and circumferentially around, the longitudinal axis.

In one aspect, the upper wedging surface is provided in a lower end of the main housing section.

In one aspect, the lower supporting element is displaceable in relation to the main housing section in the longitudinal direction.

In one aspect, the lower supporting element is connected to the main housing section by means of a bolt.

In one aspect, the lower supporting element is slidingly arranged around the bolt. Hence, the bolt allows relative axial movement between the lower wedging surface and the upper wedging surface.

In one aspect, the bolt comprises a head section, a threaded end section and an intermediate non-threaded section between the head section and the threaded end section. In one aspect, the threaded end section is threadedly connected to a threaded opening provided in the lower end of the main housing section. The lower supporting element comprises a through bore slidingly arranged around the intermediate non-threaded section of the bolt.

In one aspect, the thimble-shaped elements are made of a metal or a metal alloy.

Hence, a metal-to-metal seal is provided when the sealing element is radially expanded into contact with the well pipe. The purpose of the metal-to-metal seal is to prevent or at least considerably reduce molten heat generating mixture to flow down to the area below the well tool device during the heat generation process. The purpose of the metal-to-metal seal is also to prevent or at least considerably reduce fluid heated by the heat generation process to rise from the area below the well tool device and up into the molten heat generating mixture during the heat generation process, as this may impact the process negatively.

Alternatively, the thimble-shaped elements are not expanded entirely into contact with the well pipe. The radially expanded sealing ring will still reduce molten heat generating mixture to flow down and/or reduce fluid heated by the heat generation process to rise.

In one aspect, the well tool device comprises several sealing elements above each other, each sealing element comprising a plurality of thimble-shaped elements inserted into each other to form a torus.

Alternatively, the thimble-shaped elements are made of a ceramic or another suitable heat-resistant material.

In one aspect, the thimble-shaped elements may be coated. The thimble-shaped elements may be coated with a high-temperature polymer.

In one aspect, each of the thimble-shaped elements comprises a through bore, where the thimble-shaped elements are connected to each other by means of a connection element inserted through the respective bores.

In one aspect, the connection element is a wire. The connection element may be elastic for biasing the sealing element towards the radially retracted state. In one aspect, the connection element is a spiral spring. In one aspect, the connection element is a spiral spring for biasing the sealing element towards the radially retracted state.

In one aspect, the sealing device further comprises a ratchet device configured to allow relative axial movement between the lower wedging surface and the upper wedging surface in a direction towards each other while preventing relative axial movement between the lower wedging surface and the upper wedging surface in a direction away from each other.

In one aspect, a weight of the main housing section is configured to force the sealing device from the radially retracted state to the radially expanded state when the lower supporting element is held stationary with respect to the well pipe.

The well tool device may be held stationary by lowering the well tool device onto an object secured relative to the well pipe. The platform may be a plug set in the well pipe, it may be an inwardly protruding part of the well pipe, it may be an upper end of a pipe string section located inside the well pipe.

In one aspect, the lower supporting element comprises a downwardly facing, substantially planar, supporting surface.

The downwardly facing supporting surface is configured to be supported against a supporting surface provided in the well pipe.

In one aspect, the supporting surface may be a part of a plug set in the well pipe.

In one aspect, the lower wedging surface is facing generally upwards, while the upper wedging surface is facing generally downwards.

In one aspect, the well tool device comprises:.

wherein the main housing section comprises a compartment subsection and a distance subsection, where the compartment is located within the compartment subsection and where the distance subsection is located above the compartment subsection.

In one aspect, a height of the distance subsection is more than <NUM> meters, preferably more than <NUM> meters and even more preferred more than <NUM> meters.

In one aspect, the anchoring device comprises:.

In one aspect, the radially outwardly facing surface is provided on the upper link element or on the lower link element or on a slips element pivotably connected between the upper link element and the lower link element.

In one aspect, the well tool device has a central longitudinal axis. A radial plane is defined as a plane perpendicular to the central longitudinal axis.

In one aspect, the length of the upper link element is measured between pivoting points of the upper link element and the length of the lower link element is measured between pivoting points of the lower link element.

In one aspect, the anchoring device has a run state, in which the slips element is radially retracted, and a set state, in which the slips element is radially expanded against the well pipe.

In one aspect, the anchoring device is configured to be in a radially retracted or run state when lowered into the well pipe and where the anchoring device is configured to be in a radially expanded or set state when arriving at the desired location in the well pipe.

In one aspect, an upper end of the upper link element is pivotably connected to the upper connection section and a lower end of the upper link element is pivotably connected to an upper end of the slips element; and wherein an upper end of the lower link element is pivotably connected to a lower end of the slips element and a lower end of the lower link element is pivotably connected to the distance subsection.

In one aspect, a weight of the main housing section is configured to pull the anchoring device to a radially retracted state when the well tool device is suspended from a wire or wireline connected to the upper connection section.

The weight of the main housing section is here referring to the weight of the well tool being suspended from the lower link element of the anchoring device.

In one aspect, a weight of the upper connection section is configured to push the anchoring device to a radially expanded state when the well tool device below the anchoring device is held stationary with respect to the well pipe.

The well tool device may be held stationary by lowering the well tool device onto an object secured relative to the well pipe. The platform may be a plug set in the well pipe, it may be an inwardly protruding part of the well pipe, it may be an upper end of a pipe string section located inside the well pipe, an upper end of a cement column within the well pipe etc..

In one aspect, the serrated surface is configured to prevent upwardly directed movement of the main housing section after ignition of the heat generating mixture.

In one aspect, the slips element comprises a first, inwardly facing, stop engaging a center rod of the well tool device in the radially retracted state, causing a lower angle between the lower link element and the center rod to be more than <NUM>° and/or causing an upper angle defined between the upper link element and the center rod to be more than <NUM>°.

The purpose of the stop is to ensure that the anchoring device will be able to move radially out to the radially expanded state.

In one aspect, the slips element comprises a first stop; wherein the lower link element comprises a second stop, wherein a lower angle between the lower link element and a longitudinal center axis of the well tool device has a maximum value when the first stop and the second stop is engaged with each other.

In one aspect, the maximum value is <NUM> - <NUM>°. The purpose of the stops is to ensure that the anchoring device will be able to move back to the radially retracted state.

In one aspect, the slips element further comprises a third, inwardly facing stop for engaging the center rod of the well tool device in the radially retracted or run state.

In one aspect, the well tool device comprises three sets of upper link elements, slips elements and lower link elements distributed around the circumference of the anchoring device. The three sets of upper link elements, slips elements and lower link elements are distributed with <NUM>° between each set. Alternatively, four sets of upper link elements, slips elements and lower link elements are distributed with <NUM>° between each set of wheels. In yet an alternative, there may be only one set, the one set comprising one upper link element, one slips element and one lower link element.

In one aspect, the well tool device comprises a wheel section comprising a set of wheels.

In one aspect, the wheels are provided a first radial distance from a longitudinal center axis of the well tool device, wherein the radially protruding surface of the slips element is provided at a second radial distance from a longitudinal center axis of the well tool device, the first radial distance being larger than the second radial distance.

In one aspect, the wheel section comprises three wheels. The purpose of the wheel section is to reduce friction during running of the well tool device into the well pipe and to reduce friction during retrieval of at least parts of the well tool device from the well pipe. The purpose of the wheel section is also to center the well tool device in the well pipe. In one aspect, the wheel section is provided axially between the anchoring device and the upper connection section.

In one aspect, the wheel section is a part of the anchoring device, where the wheels and the upper end of the upper link element are connected to a common bracket.

In one aspect, the distance subsection comprises an elongated housing outside of the center rod. The purpose of the distance subsection is to increase the distance between the anchoring device and the main housing section. During the heat generation process, the distance subsection is designed to at least partially melt, allowing the upper connection section, the anchoring device and the non-melted parts of the distance subsection to be retrieved from the well pipe.

In one aspect, the well tool device comprises an igniting device for igniting the heat generating mixture. The igniting device may be trigged by an electric signal received via a wire connected to the upper connection interface. Alternatively, the ignition device may be trigged by a wireless signal, a timer, a pressure sensor, etc..

In one aspect, the upper connection section comprises a connection interface. The connection interface a may be a wire or wireline connection interface. No setting and/or retrieval tool is needed to set and/or retrieve the well tool device - a wire or wireline is sufficient.

Heat from the molten heat generating mixture will be drawn via the thimble-shaped elements to the lower end of the main housing section and to the lower supporting element. Hence, the lower end of the main housing section and the lower supporting element are working as a heat-sink, for cooling the thimble-shaped elements.

The present invention also relates to a method of transporting a heat generating mixture into a well pipe using a well tool device according to the above, wherein the method comprises the steps of:.

The term "slips element" is used herein to describe an element having an outwardly facing serrated surface having at least one tooth, wherein the serrated surface is capable of engaging with the inner surface of the well pipe and hence prevent upwardly and/or downwardly movement of the slips element. Typically, the serrated surface will comprise a number of teeth adjacent to each other. The tooth/teeth of the serrated surface may be shaped to prevent upwardly movement only, downwardly movement only, or both upwardly and downwardly movement.

The term "upper", "above", "lower", "below" etc. are used herein as terms relative to the well. Parts referred to as "upper" or "above" are relatively closer to the top of the well than the parts referred to as "lower" or "below", which are relatively closer to the bottom of the well, irrespective of the well being a horizontal well, a vertical well or an inclining well.

Embodiments of the invention will now be described with reference to the enclosed drawings, where:.

It is now referred to <FIG>, where a well tool device <NUM> is disclosed within a well pipe WP. The purpose of the well tool device <NUM> is to transport a heat generating mixture HGM to a desired location within an oil and/or gas well. The well is typically provided with a well pipe WP cemented or in other ways secured inside the well.

The heat generating mixture HGM will, when ignited by an igniting device IGN, start a heat generating process. One such heat generating process may be a part of a plugging and abandonment operation as described in <CIT>, i.e. to melt surrounding materials to form a solid plug. Another such heat generating process may be a part of a well pipe removal operation, where the well pipe WP (and possibly also other well pipes radially outside of the inner well pipe WP) becomes at melted or least partially melted. The purpose of the latter operation may be to expose the rock of the well. Yet another such heat generating process may be to provide heat, for example to heat a metal, a metal alloy or another material to its liquid state during a period of time.

In <FIG>, it is described that the well tool device <NUM> comprises a connection section <NUM>, a main housing section <NUM>, an anchoring device <NUM> and a sealing device <NUM>. In addition, the well tool device <NUM> may comprise a wheel section <NUM>. These parts will be described in detail below.

Centrally within the well tool device <NUM> is a mandrel or central rod <NUM>. The central rod <NUM> is secured to the connection section <NUM>. Other parts of the well tool device <NUM> is slidingly engaged outside of the central rod <NUM>, as will be apparent from the description below.

It is further shown in <FIG> that the well tool device <NUM> is defined with a longitudinal center axis I-I, where a radial plane is defined as a plane perpendicular to the central longitudinal axis I-I.

It is now referred to <FIG>, <FIG>. The connection section <NUM> is provided in the upper end of the well tool device <NUM> and comprises a connection interface 11a. The connection interface 11a may be a wire or wireline connection interface. A wire or wireline (not shown) is connected directly to the connection interface 11a. Hence, in the present embodiment, no setting tool is required to run and set the well tool device <NUM> at the desired location in the well. No retrieval tool is used when retrieving the tool or parts of the tool either.

It is now referred to <FIG>. The main housing section <NUM> is provided above the sealing device <NUM> and below the anchoring device <NUM>. The main housing section <NUM> comprises a compartment subsection <NUM> and a distance subsection <NUM> located above the compartment subsection <NUM>.

The compartment subsection <NUM> comprises an outer housing 15a and a compartment <NUM> located within the outer housing 15a. The lower end of the outer housing 15a is closed. The upper end of the outer housing 15a, i.e. The transition area between the compartment subsection <NUM> and the distance section <NUM> is also closed. Hence, the compartment <NUM> is a closed compartment.

The compartment <NUM> will typically contain the heat generating mixture HGM. In <FIG> and <FIG> the heat generating mixture HGM is shown as a particulate matter. However, it should be noted that the heat generating mixture HGM may comprise one solid piece of a heat generating material or it may comprises heat generating material in the form of a slurry or fluid.

As shown in <FIG>, the main housing section <NUM> comprises a bore 14a in which the center rod <NUM> is provided. The center rod <NUM> is axially displaceable in the bore 14a. This is also shown in <FIG>, where a distance D12 between a lower end of the rod <NUM> and a lower end of the bore 14a is longer in the run state (<FIG>) than in the set state (<FIG>).

In <FIG> it is shown that the main housing section <NUM> has a height H14, the compartment subsection <NUM> has a height H15 and the distance section <NUM> has a height H17. The height H14 is substantially equal to the sum of heights H15 and H17. It should be noted that the height H15 may be substantially larger than shown in the drawings, as indicated by break line BR15. The height H15 will be dependent on the amount of heat generating mixture HGM needed for the operation. It should also be noted that the height H17 may be substantially larger than shown in the drawings, as indicated by break line BR17. The purpose of the distance subsection <NUM> is to create a distance between the anchoring device <NUM> and the heat generating mixture HGM, to avoid that the heat generating process melts the anchoring device <NUM> in the heat generating process or in an early phase of the heat generating process. The height H17 of the distance subsection <NUM> may be more than <NUM> meters, preferably more than <NUM> meters and even more preferred more than <NUM> meters.

The anchoring device will now be described with reference to <FIG> and <FIG>.

The anchoring device <NUM> is connected between the upper connection section <NUM> and the distance section <NUM>. The anchoring device <NUM> comprises a slips element <NUM> with a radially outwardly facing surface 22a with serrations for engaging the well pipe WP in the set state. The anchoring device <NUM> further comprises an upper link element <NUM> pivotably connected between the upper connection section <NUM> and the slips element <NUM> and a lower link element <NUM> pivotably connected between the slips element <NUM> and the main housing section <NUM>. An upper end 24a of the upper link element <NUM> is pivotably connected to the upper connection section <NUM> at a first pivoting point P1 and a lower end 24b of the upper link element <NUM> is pivotably connected to an upper end of the slips element <NUM> at a second pivoting point P2. An upper end 26a of the lower link element <NUM> is pivotably connected to a lower end of the slips element <NUM> at a third pivoting point P3 and a lower end 26b of the lower link element <NUM> is pivotably connected to the distance subsection <NUM> at a fourth pivoting point P4.

As described above, the center rod <NUM> is secured to, and hence fixed with respect to, the upper connection section <NUM>. Hence, by axial displacement of the distance subsection <NUM> relative to the upper connection section <NUM>, the anchoring device <NUM> can be moved between its radially retracted state and its radially expanded state.

A line drawn between the first and fourth pivoting points P1, P4 is preferably parallel to the central longitudinal axis I-I. Similarly, a line drawn between the second and third pivoting points P2, P3 when the anchoring device is in its run or set states is preferably parallel to the central longitudinal axis I-I.

The upper link element <NUM> has a length L24 measured between the first and second pivoting points P1, P2. The lower link element <NUM> has a length L26 measured between the third and fourth pivoting points P3, P4. The length L24 is longer than the length L26.

In <FIG> it is further shown an upper angle α24 between the upper link element <NUM> and the longitudinal axis I-I. Here, the upper angle α24 is shown as the angle between a dashed line drawn between P1 and P4 (being parallel to the longitudinal axis I-I) and a dashed line drawn between P1 and P2.

Similarly, it is shown in <FIG> a lower angle α26 between the lower link element <NUM> and the longitudinal axis I-I. Here, the lower angle α26 is shown as the angle between a dashed line drawn between P1 and P4 (being parallel to the longitudinal axis I-I) and a dashed line drawn between P3 and P4.

In <FIG> it is shown that the slips element <NUM> comprises a first downwardly facing stop 22e. Moreover, it is shown that the lower link element <NUM> comprises a second, upwardly facing stop 26e. In <FIG>, it is shown that the first downwardly facing stop 22e is engaging the second, upwardly facing stop 26e, thereby defining a maximum value α26max for the lower angle α26. It is not possible to increase the lower angle α26 further than this maximum value α26max due to the stops 22e, 26e. The purpose of the stops 22e, 26e is to ensure that the anchoring device <NUM> will be able to move back to the radially retracted state.

In <FIG> it is shown that the slips element <NUM> further comprises a third, inwardly facing stop 22c. In <FIG>, it is shown that this inwardly stop 22c is engaging the center rod <NUM> of the well tool device <NUM> in the radially retracted or run state. The purpose of the third stop 22c is to ensure that the lower angle α26 between the lower link element <NUM> and the center rod <NUM> is more than <NUM>° and/or to ensure that the upper angle α24 defined between the upper link element <NUM> and the center rod <NUM> is more than <NUM>°.

Consequently, the stop 22c will ensure that the anchoring device <NUM> will be able to move radially out to from the radially retracted state to the radially expanded state.

The preferred value for the maximum value α26max is <NUM> - <NUM>°. In the embodiment shown in the drawings, the maximum value α26max is <NUM>°.

The upper link element <NUM> may as an example have an angle α24 between <NUM> - <NUM>° with respect to a longitudinal axis (I-I) in the radially expanded state.

As shown in the drawings, the well tool device <NUM> comprises three sets of upper link elements, slips elements and lower link elements distributed with <NUM>° between each set around the circumference of the center rod <NUM>.

Alternatively, four sets of upper link elements, slips elements and lower link elements may be distributed with <NUM>° between each set around the circumference of the center rod <NUM>.

It is now referred to <FIG>. The sealing device <NUM> is provided below the main housing section <NUM>.

The sealing device <NUM> comprises a sealing ring <NUM>. The sealing ring <NUM> is shown in detail in <FIG> and comprises a plurality of thimble-shaped elements <NUM> inserted into each other to form a torus. When viewed from the side as in <FIG>, each thimble-shaped element comprises an outwardly curved area <NUM>, an inwardly curved area <NUM> and possibly a straight area <NUM> between the areas <NUM>, <NUM>. The outwardly curved area <NUM> of one element is inserted into the inwardly curved area <NUM> of the adjacent element. The thimble-shaped elements <NUM> are known from <CIT>, where a plugging device is described having a sealing element made of an elastomeric material, where the thimble-shaped elements are incorporated into the elastomeric material. The purpose of the thimble-shaped elements is to prevent or at least partially reduce extrusion of the elastomeric material in situations where there is a large pressure difference over the plug. Here, it is described that a wire may or may not be inserted through an opening <NUM> of the elements.

In the present sealing ring <NUM>, the thimble-shaped elements <NUM> are connected to each other by means of a connection element <NUM> inserted through the respective bores <NUM>. Here, the connection element <NUM> has the purpose of biasing the sealing element <NUM> to its radially retracted state. In <FIG>, it is shown that the connection element <NUM> is a spiral spring. Alternatively, the connection element <NUM> may be an elastic wire for biasing the sealing ring <NUM> towards the radially retracted state.

The thimble-shaped elements <NUM> are preferably made of a metal or a metal alloy. They may be coated with a high-temperature polymer. Alternatively, the thimble-shaped elements <NUM> are made of a ceramic or another suitable heat-resistant material.

The sealing device <NUM> further comprises a lower supporting element <NUM> comprising a lower wedging surface 56a and an upper wedging surface 54a faced towards the lower wedging surface 56a. The sealing ring <NUM> is provided between the lower wedging surface 56a and the upper wedging surface 54a. The upper wedging surface 54a and the lower wedging surface 56a are provided radially outside of, and circumferentially around, the longitudinal axis I-I. Similarly, the sealing ring <NUM> is provided circumferentially around and outside of the longitudinal axis I-I.

Relative axial movement between the lower wedging surface 56a and the upper wedging surface 54a in a direction towards each other provides radial expansion of the sealing element <NUM>. As the sealing ring <NUM> comprises a plurality of thimble-shaped elements, each element will move a relatively small distance away from other elements when going from the retracted state to the expanded state. However, the outwardly curved area <NUM> of one element will still be at least partially inserted into the inwardly curved area <NUM> of the adjacent element and the thimble-shaped elements will still form a torus-shaped ring (thought with a larger diameter in the expanded state than in the retracted state).

The term "wedging surface" is used herein to describe a surface which, when moved towards another "wedging surface", will wedge the sealing ring <NUM> radially outwards. It should be noted that both of the wedging surfaces may have an acute angle with respect to a radial plane. However, it is also possible that one of the surfaces is oriented in the radial plane while the other one of the surfaces is provided with an acute angle with respect to the radial plane.

The upper wedging surface 54a is here provided in a lower end <NUM> of the main housing section <NUM>.

The lower supporting element <NUM> is displaceable in relation to, and connected to the lower end <NUM> of the main housing section <NUM> by means of, a bolt <NUM>. The bolt <NUM> comprises a head section 61a, a threaded end section 61b and an intermediate non-threaded section 61c between the head section 61a and the threaded end section 61b.

The threaded end section 61b is threadedly connected to a threaded opening <NUM> provided in the lower end <NUM> of the main housing section <NUM>. The lower supporting element <NUM> comprises a through bore <NUM> slidingly arranged around the intermediate non-threaded section 61c of the bolt <NUM>.

The lower supporting element <NUM> comprises a downwardly facing, substantially planar, supporting surface <NUM>. This surface <NUM> defines the lower end of the well tool device <NUM>.

The sealing device <NUM> further comprises a ratchet device <NUM> configured to allow relative axial movement between the lower wedging surface 56a and the upper wedging surface 54a in a direction towards each other while preventing relative axial movement between the lower wedging surface 56a and the upper wedging surface 54a in a direction away from each other.

Hence, if the lower supporting element <NUM> and the lower end <NUM> of the main housing section <NUM> are moved relatively towards each other, the ratchet device <NUM> will allow such movement. However, it is not possible for the lower supporting element <NUM> and the lower end <NUM> of the main housing section <NUM> to move away from each other again, due to the ratchet device <NUM>. The ratchet device <NUM> comprise a finger element <NUM> having a first end 81a secured to lower end <NUM> and a second end 81b provided with a toothed surface engaging a toothed surface of a bore <NUM> provided in the lower supporting element <NUM>.

It is now referred to <FIG>, wherein it is shown that the well tool device <NUM> comprises a wheel section <NUM> comprising a set of wheels <NUM>.

The wheel section <NUM> is located axially above the anchoring device <NUM> and below the upper connection section <NUM>. In the present embodiment, the wheel section <NUM> is a part of the anchoring device <NUM>, where the wheels <NUM> and the upper end 24a of the upper link element <NUM> are connected to a common bracket <NUM>. Still, the wheels <NUM> are located axially above the slips element <NUM>.

The wheel section <NUM> comprises three wheels <NUM>. The purpose of the wheel section <NUM> is to reduce friction during running of the well tool device into the well pipe WP and to reduce friction during retrieval of at least parts of the well tool device <NUM> from the well pipe WP. The purpose of the wheel section <NUM> is also to center the well tool device <NUM> in the well pipe WP.

It is now referred to <FIG>, showing the anchoring device in its run state. Here, the wheels <NUM>, more precisely the outwardly facing surfaces of the respective wheels <NUM>, are provided a first radial distance r92 from a longitudinal center axis I-I of the well tool device <NUM>. Moreover, the radially protruding surface 22a of the slips element <NUM> is provided at a second radial distance r22a from a longitudinal center axis I-I of the well tool device <NUM>. It is apparent that the first radial distance r92 is larger than the second radial distance r22a. Hence, the wheels also prevent the serrated surface 22a of the slips element <NUM> to accidentally come into contact with the inner surface of the well pipe during run or retrieval.

Initially, it is referred to <FIG>, where it is shown an upper weight W11 representing the weight of the upper connection section <NUM>. As the center rod <NUM> is secured to this upper connection section <NUM>, the weight of the center rod <NUM> will be included in this upper weight W11.

In <FIG>, a lower weigh W14 is shown to represent the weight of the main housing section <NUM>, including the weight of the heat generating mixture HGM.

The operation of the well tool device <NUM> will now be described with reference to <FIG>.

In <FIG>, it is shown an oil/gas well WL comprising a well pipe WP set inn the well WL. The well pipe WL may here be a production tubing. Radially outside of the well pipe WL there is an well casing WC secured to the formation by means of cement. An annulus is present between the well pipe WP and the well casing WC. The annulus may be filled with a fluid, or it may be filled with cement.

A permanent plug PP has been set in the well pipe WP. The upper part of the permanent plug PP is forming a supporting surface SS for the well tool device <NUM>.

<FIG> shows that the well tool device <NUM> has been lowered into or run into the well pipe WP by means of a wireline WL to a position above the supporting surface SS. During this running operation, the weight W14 of the main housing section <NUM> is pulling the anchoring device <NUM> to its radially retracted state. As described above, the main housing section <NUM> is suspended via the lower link element <NUM> of the anchoring device <NUM>, and hence the weight W14 will pull the anchoring device <NUM> downwardly and radially inwards to the retracted state.

<FIG> shows that the well tool device <NUM> has been lowered until the downwardly facing supporting surface <NUM> supported against the supporting surface SS. As shown, there is no tension in the wireline WL. The weight W14 of the main housing section <NUM> is now pushing the upper wedging surface 54a downwards towards the lower wedging surface 56a, bringing the sealing device <NUM> from the radially retracted state to the radially expanded state. In the present embodiment, the sealing ring <NUM> is expanded into contact with the inner surface of the well pipe WP. When the sealing device is in its radially expanded state, the main housing section <NUM> becomes stationary with respect to the well pipe WP.

As the main housing section <NUM> now is stationary, the weight W11 of the upper connection section <NUM> will push the anchoring device <NUM> to the radially expanded state. The serrated surface of the slips element <NUM> will be brought into contact with the inner surface of the well pipe and the anchoring device <NUM> is now anchored to, or engaged with, the well pipe.

In <FIG>, the heat generating mixture HGM has been ignited or started and the hatched area represents a heat generating process HGP. The heat generation process HGP will melt the compartment subsection <NUM> and at least parts of the well pipe WP. In the present embodiment, the heat generation process HGP will melt also some of the materials radially outside of the well pipe WP, such as the well casing WC and cement present outside of the well casing WC. However, due to the distance subsection <NUM>, the heat generation process HGP will not melt the anchoring device <NUM>. Hence, as shown in <FIG>, the heat generation process HGP may melt parts of, but not the entire, distance subsection <NUM>.

Due to the heat generating process HGP a fluid pressure will typically be built up. The purpose of the anchoring device <NUM> is to prevent that the main housing section <NUM> will be pushed upwards into the well pipe because of this fluid pressure. Hence, the heat generating process will be contained in the desired area of the well. This pressure can be large. However, due to lower link element <NUM> being shorter than the upper link element and/or due to the lower angle α26 being larger than the upper angle α24, a considerable force will push the serrated surface 22a of the slips <NUM> into the well pipe and prevent upwardly directed movement of the main housing section <NUM> during the heat generating process HGP.

A further consequence of the heat generating process HGP is that materials will become melted. The metal-to-metal seal provided when the sealing element <NUM> is radially expanded into contact with the well pipe WP will prevent or at least considerably reduce molten heat generating mixture and other molten materials (for example molten metal of the well pipe) to flow down to the area below the well tool device <NUM> during the heat generation process.

Yet another consequence of the heat generating process HGP is that fluid present in a compartment CO between the permanent plug PP and the supporting surface <NUM> will start to boil. Hence, another purpose of the metal-to-metal seal is also to prevent or at least considerably reduce the amount of fluid heated by the heat generation process to rise from the compartment CO below the well tool device <NUM> and up into the molten heat generating mixture during the heat generation process, as this may impact the process negatively.

In the final stage of the heat generating process HGP, the upper connection section <NUM>, the anchoring device <NUM> and possibly also parts of the distance subsection <NUM> may be retrieved from the well pipe by pulling in the wireline, as indicated by the arrow adjacent to the wireline WL. The operation is now finished.

It is now referred to <FIG>, showing an optional step performed before the well tool device <NUM> is lowered into the well pipe WP. In this example, the annulus AN is fluid-filled. Here, a tool as described in <CIT> <CIT> or <CIT> is used to first perforate the well pipe WP as shown in <FIG> by means of a tool CS.

Then, as shown in <FIG>, the tool CS is injecting a sealing material in fluid phase into the perforations, where the material in fluid phase subsequently will solidify to form a barrier in the annulus. Also the well pipe above the permanent plug may be filled with this material, to fill the compartment CO to avoid the above boiling challenges.

It is also possible to inject a particulate material into the perforations. It is further possible to inject a material such as heat generating mixture or a material being part of or affecting the heat generating process into the perforations, instead of or after the sealing material mentioned above.

In <FIG>, the well tool device <NUM> has been lowered onto the supporting surface SS formed by the injected and solidified material.

It should be noted that if the above perforation process has damaged the well pipe and made it difficult to obtain a metal-to-metal seal between the sealing ring <NUM> and the inner surface of the well pipe, the sealing device <NUM> of the well tool device may comprise several sealing rings <NUM> above each other, where each sealing ring <NUM> is expanded radially out towards the well pipe WP.

It should further be noted that the well tool device <NUM> may be set towards other supporting surfaces SS than a permanent plug. One example is the above injected and solidified material, the supporting surface SS may also be an inwardly protruding part of the well pipe WP, an upper end of a pipe string section located inside the well pipe etc..

It should further be noted that some pipes have variations in their inner diameter and also their shape may vary (for example slightly oval cross section instead of perfectly circular cross section). Hence, in some cases, the thimble-shaped elements <NUM> are not expanded entirely into contact with the well pipe WP. The radially expanded sealing ring will still reduce molten heat generating mixture to flow down and/or reduce fluid heated by the heat generation process to rise.

Some alternative embodiments have been described above. It is now referred to <FIG>, where an alternative embodiment of the anchoring device <NUM> is shown.

This alternative embodiment has many similarities with the above described embodiment, and only differences between the embodiments will be described herein.

The main difference is that here, the anchoring device <NUM> does not comprise a separate slips element pivotably connected between the upper link element <NUM> and the lower link element <NUM>. Instead, the lower end of the upper link element <NUM> is pivotably connected directly to the upper end of the lower link <NUM>, as indicated by the one, common pivoting point indicated as P2, P3 in <FIG>.

The radially outwardly facing surface 22a is here provided on the lower link element <NUM>. Alternatively, it can be provided on the upper link element <NUM>.

Here, the first stop 22e is provided on the upper link element <NUM> while the second stop 26e is provided on the lower link element <NUM>. Similarly to the above embodiment, the lower angle α26 between the lower link element <NUM> and a longitudinal center axis I-I of the well tool device <NUM> has a maximum value α26max when the first stop 22e and the second stop 26e is engaged with each other. Moreover, it is shown in <FIG> that the anchoring device <NUM> also comprises a third, inwardly facing, stop 22c. Also here the stop 22c is provided in contact with the centre rod in the run state. In this embodiment, the stop 22c is provided as part of the lower link element.

Claim 1:
Well tool device (<NUM>) for transporting a heat generating mixture (HGM) into a well pipe (WP) and, after ignition of the heat generating mixture (HGM), reduce molten heat generating mixture (HGM) to flow down, wherein the well tool device (<NUM>) comprises:
- an upper connection section (<NUM>);
- a main housing section (<NUM>) comprising a compartment (<NUM>) for the heat generating mixture (HGM);
- a sealing device (<NUM>) provided below the main housing section (<NUM>);
characterized in that the sealing device (<NUM>) comprises:
- a lower supporting element (<NUM>) comprising a lower wedging surface (56a);
- an upper wedging surface (54a) faced towards the lower wedging surface (56a);
- a sealing element (<NUM>) provided between the lower wedging surface (56a) and the upper wedging surface (54a);
wherein the sealing element (<NUM>) comprises a plurality of thimble-shaped elements (<NUM>) inserted into each other to form a torus;
- wherein relative axial movement between the lower wedging surface (56a) and the upper wedging surface (54a) in a direction towards each other provides radial expansion of the sealing element (<NUM>).