FR3038336B1 - MOBILE WELL INTERVENTION UNIT - Google Patents

Abstract

The invention relates to a mobile well intervention unit comprising: a rolling platform (1), a heating tool (20) intended to be lowered into a well (6), a cable storage device comprising a drum (8). ) and a motor (15) coupled to the drum for driving the drum in rotation in both directions, a multifunctional cable (9) wound on the drum, and a connector (21) for detachably connecting the cable to the tool for heating, a mobile return device comprising a return pulley (10), and a handling device (14) mounted on the platform adapted to move the return device between a storage position (13) in which the return device is placed at a predetermined location on the rolling platform, and a service position in which the mobile return device is vertical to the wellbore.

Description

TECHNICAL FIELD The invention relates to the field of intervention equipment intended to be lowered into an underground well, in particular an oil well, and more particularly to the field of heating equipment for such a well.

Technological background

It is well known that in primary recovery, oil recovery can usually be performed only up to 10-20% of the contents of the geological reservoir for various reasons. Phenomena that may reduce the productivity of a well include paraffin buildup and Joule-Thompson cooling.

There is therefore a need for treatment equipment that can improve the productivity of an underground well, particularly for the production of oil, methane, potassium hydroxide, saline solution or other. summary

An idea underlying the invention is to heat an underground layer to evaluate its production potential and recovery. Another idea underlying the invention is to provide a practical equipment of use for this.

According to one embodiment, the invention provides a mobile well intervention unit comprising: a rolling platform, an induction heating tool intended to be lowered into a wellbore for heating an underground layer, a storage device for cable comprising a support frame fixed on the platform, a drum pivotally mounted on the support frame and a motor coupled to the drum to drive the drum in rotation in both directions, the pivot axis of the drum extending in one direction transverse platform of the rolling platform, a multifunctional cable at least partially wound on the drum, the multifunctional cable comprising at least one support rope and at least one power supply cord, a first end of the multifunctional cable carrying a connector for connecting the detachable way the multifunctional cable to the induction heating tool, a return device oi mobile, the return device comprising a support bearing and a return pulley pivotally mounted on the support bearing, and a handling device mounted on the platform, the handling device comprising a motorized arm adapted to move the return device between a storage position in which the deflection device is placed at a predetermined location on the rolling platform, and a service position in which the mobile return device is placed in alignment with the rolling platform beyond a longitudinal end of the rolling platform to be vertical to the wellbore where the induction heating tool is to be lowered and in which the pivot axis of the idler pulley extends parallel to the pivot axis of the drum.

With such a mobile unit, all the equipment required for the well heating treatment can be brought to the site and easily deployed for a shorter or longer duration of intervention, typically of a few days.

According to advantageous embodiments, such a device may have one or more of the following characteristics:

In one embodiment, the support frame of the cable storage device is located in a forward longitudinal portion of the platform and the handling device is mounted in a rear longitudinal portion of the platform, the service position of the return device. movable being located beyond a rear longitudinal end of the platform.

In one embodiment, the rolling platform has a horizontal upper support surface, the pivot axis of the reel and the pivot axis of the idler pulley in the service position being located above the support surface. . Preferably, a height of the pivot axis of the reel and a height of the pivot axis of the deflection pulley relative to the support surface are adjacent to each other; for example, the difference between the height of the pivot axis of the reel and the height of the pivot axis of the return pulley is less than the diameter of the return pulley. Thanks to these characteristics, the vertical space and the wind resistance of the intervention unit can be relatively limited, which promotes the good stability of the intervention unit, especially during a long-term intervention .

In one embodiment, the support frame and the reel of the cable storage device comprise contact elements held in sliding electrical contact during rotation of the reel, the multifunctional cable having a second end coupled to the contact element of the reel. drum to receive electrical power supply through the contact elements.

In one embodiment, the mobile unit further comprises a generator arranged on the platform and connected to the contact element of the support frame for supplying electrical power supply through the contact elements. embodiment, the electric power supply power is provided by an electrical network external to the mobile unit.

In one embodiment, the reel has an inner cylindrical core for winding the multifunctional cable into at least one inner layer resting on the inner cylindrical core and a removable outer cylindrical shell adapted to be disposed around the inner cylindrical core coaxially with the core. internal cylindrical for winding the multifunctional cable into at least one outer layer resting on the outer cylindrical shell. Thanks to these characteristics, it is possible to store, wind and unroll a large diameter cable of great length in the form of several layers whose radial load is taken separately by the inner cylindrical core and the outer cylindrical shell respectively, which avoids generating excessive crushing forces on the inner cable layer (s).

Preferably in this case, the reel further comprises two end plates arranged at the two axial ends of the inner cylindrical core and extending radially protruding from the inner cylindrical core, the outer cylindrical shell being formed of a plurality of plates having an arcuate profile and having two longitudinal ends respectively attachable to the two end flanges of the drum.

In one embodiment, the induction heating tool comprises a connection head having a threaded cylindrical housing and electrical connection pins located at the bottom of the threaded cylindrical housing, the connector comprising a threaded outer bushing that can be screwed into the socket. cylindrical housing threaded with the connection head to take up the weight of the tool and a female electrical connector adapted to cooperate with the electrical connection pins located at the bottom of the cylindrical housing to establish an electrical connection between a heating circuit of the tool induction heater and said at least one multifunctional cable power supply cable. For example, the connection pins are male connection pins. With these features, the induction heating tool can be easily connected and disconnected from the cable with each use, for easy storage and transport of the tool.

In one embodiment, the multifunctional cable has a length greater than 1000 m, an outer diameter greater than 20 mm and a permanent minimum bending radius greater than 140 mm, and the reel has a diameter greater than 3 m. Thanks to these characteristics, a high power power supply can be transported in the cable to develop a high heat output.

According to one embodiment, the invention also provides a method of operating the aforementioned mobile unit, comprising: arranging the rolling platform near the head of a wellbore where the induction heating tool is to be down, the return device being in the storage position, introduce the induction heating tool in the wellhead with the motorized arm of the handling device to an intermediate position in which the connection head of the induction heating tool remains outside the wellhead attach the induction heating tool to the wellhead in the intermediate position by means of a static fastener, move the motorized arm to release the space between the reel and the idler pulley, place the return device in the service position using the motorized arm of the handling device, lay the multifunctional cable on the idler pulley to bring the connector close to the connection head of the induction heating tool, connect the connector to the connection head of the induction heating tool, release the tool inductively heating the static securing device to suspend the induction heating tool from the multifunctional cable, and lowering the induction heating tool into the wellbore using the multifunctional cable.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be better understood, and other objects, details, features and advantages thereof will become more clearly apparent from the following description of several particular embodiments of the invention, given solely for the purposes of the invention. illustrative and not limiting, with reference to the accompanying drawings. - Figure 1 is a schematic side view of a mobile intervention unit on a well according to one embodiment of the invention, the mobile return device being in the service position. FIG. 2 is a schematic view from above of the mobile unit of FIG. 1. FIG. 3 is a schematic side view of a second embodiment of the mobile return device. - Figure 4 is a sectional view of a connector arranged at the end of a multifunctional cable, the connector being shown in a connected state with an induction heating tool of the mobile unit of Figure 1. - FIG. 5 is a sectional view of a multifunctional cable of the mobile unit of FIG. 1, the end of which is connected to the connector of FIG. 4, along the axis VV. - Figure 6 is a sectional view of the connector of Figure 4 along the axis VI-VI. - Figure 7 is a sectional view of the connector of Figure 4 along the axis VII-VII. - Figure 8 is a sectional view of the connector of Figure 4 along the axis VIII-VIII. - Figure 9 is a sectional view of a head of the induction heating tool of Figure 4 along the axis IX-IX. FIG. 10 is a schematic side view in section of a step of connection or disconnection between the connector and the induction heating tool.

Detailed description of embodiments

Figures 1 and 2 show a rolling platform made here in the form of a trailer 1 for heavy trucks 12m long by 2m60 wide, on which are arranged different elements for carrying out operations in a well, to achieve heating an underground area.

The trailer 1 comprises a plate 2 made of steel of substantially rectangular shape mounted on three axles. The plate 2 comprises a hooking system 7 for attachment to a motorized vehicle, in order to be able to move the trailer 1 in order to approach a well 6. The plate 2 also comprises movable feet 3 adjustable by crank to stabilize the trailer 1 on the ground 5 during operations in the well 6.

A reel support frame 4 is disposed on the front of the tray 2 and a movable return device 11 carrying a return pulley 10 can be arranged in its storage position on the rear of the tray 2.

A drum 8 is pivotally mounted on the support frame 4, along an axis Y perpendicular to the direction of the length of the plate 2, represented by an axis X. The drum 8 has a diameter of approximately 3m. Around the drum 8 is wound a multifunction cable 9, for example 1500 meters long. The return pulley 10 is also pivotally mounted on a support bearing 12 of the movable return device 11 along an axis y. The multifunction cable 9 extends substantially horizontally from the drum 8 to the return pulley 10 around which it is returned vertically. The end of the multifunction cable 9 is equipped with a connector 21 to suspend the multifunction cable 9 a heating tool 20.

Referring again to FIGS. 1 and 2, the movable return device 11 is movable in both directions from a first position, which is a service position, shown in FIGS. 1 and 2, to a second position 13, which is a transport position, shown in dashed lines in FIG. 2. The handling of the mobile return device 11 from the first position to the second position 13 is enabled by the use of a pivoting crane 14 also arranged on the plate 2. The crane 14 is eccentric with respect to the axis X so as not to hinder the passage of the cable 9. When not in use, its arm is folded for the same reasons. In use, its arm carries a pulling cable, not shown, on which is suspended the mobile return device 11. The crane 14 pivots from the first position to the second position 13 to move the mobile return device 11. In the first position, the support bearing 12 is fixed to the plate 2 by an attachment 47, so that the support bearing 12 protrudes from the plate 2 longitudinally. Thus, the axis y of rotation of the pulley 10 is perpendicular to the axis X. The support bearing 12 is therefore in alignment with the plate 2. The support bearing 12 makes it possible to position the output of the multifunction cable 9 of the pulley 10 opposite the inlet of the well 6 so that the multifunction cable 9 is returned to the well 6.

The reel 8 makes it possible to deliver an adjustable length of multi-function cable 9 to the pulley 10 in order to introduce at controlled speed an adjustable length of multi-function cable 9 into the well 6. An operator can thus introduce the heating tool 20 in the well 6. To do this, the drum 8 and the pulley 10 are each respectively driven by a respective motorized pulley 15 by means of transmission belts 16. The two motorized pulleys 15 are synchronized so that the multifunction cable 9 undergo no elongation. The drum 8 can also be driven in the opposite direction to wind the multifunction cable 9 to extract the heating tool 20 from the well 6, for example at a speed of 15 meters / minute. The motorized pulleys 15 are rotated by hydraulic motors, powered by hydraulic pumps 17 also arranged on the plate 2. These hydraulic pumps 17 are supplied with electrical power by a diesel generator 18 also disposed on the plate 2. The diesel generator 18 is for example a three-phase generator of nominal power equal to 40KVA operating at 480volt and 60Hz for the Americas, but 400V, 50Hertz in Europe. A diesel fuel tank, not shown, having a capacity sufficient to allow 72 hours of operation is also provided on the plate 2. The diesel generator 18 is enclosed in a sealed housing with oil circuits and protection at low temperature and lockable access panels. A control booth 19 arranged on the plate 2 makes it possible to control the power supply and the direction of rotation of the drum 8. It preferably has windows for a visual monitoring of the operations. Now, again with reference to Figures 1 and 2, the drum 8 will be described in more detail.

The drum 8 consists of a central cylindrical core 24 of Y axis bounded on either side by concentric circular lateral flanges of Y axis. The strands of cables 9 are cut in a first layer so that the winding of the multifunction cable 9 on the central cylindrical core 24 has contiguous turns. The diameter of the core 24, which is 3m, is chosen so that the radius of curvature of the multifunction cable wound around the central cylindrical core 24 is greater than the minimum radius of curvature of the multifunction cable 9. In order to wind a second layer of cable multifunction 9 without crushing the strands of the first layer, five or six spacer plates 124, each in the form of a shell of a fifth or a sixth cylinder, are placed above the first layer of 9 multifunction cable multifunction to cover substantially the first layer. The spacer plates 124 are integral with the flanges 25 and provide an orifice for the passage of the multifunction cable 9 between the first layer and the second layer. When the multifunction cable 9 is unwound to the first layer, the spacers 124 are dismounted manually and stored on the plate 2 in a dedicated housing 34. The multifunction cable 9 can be wound up to three times around the central cylindrical core 24 , as required.

The multifunction cable 9 is wound on the drum 8 so that the end of the multifunction cable 9 is extracted from the top of the drum 8, and the multifunction cable 9 runs in a substantially longitudinal direction, in the direction from the front of tray 2 towards the rear of tray 2. Now, again with reference to FIGS. 1 and 2, a first embodiment of movable forwarding device 11 will be described in more detail. In this first embodiment, the multifunction cable 9 is stretched substantially horizontally from the top of the drum 8 to the top of the pulley 10 around which it winds about a quarter of a circle with a radius of curvature identical to pulley diameter 10. Thus, the multifunction cable 9 is returned from a horizontal position to a vertical position, in order to enter the well 6 which is vertical from the rear of the pulley 10, at the end of the bearing 12. The multifunction cable 9 will be described later in more detail with reference to FIGS. 5 to 9. The minimum radius of curvature of the multifunction cable 9 is close to

Ι, Η-ΟΙΙΙ. IUHUUHUIUUIUUHUUHUIUIUIUIUIUIUIUIUIUIUIUIUIUIUIHUIUIHUIHUIHUIHUIHUIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII In the first case, the radius of curvature is the minimum radius of curvature, equal to 1.48 m. In the second case, the radius of curvature is less. Thus, the diameter of the pulley, 3m, is chosen so that the radius of curvature of the multi-function cable 9 wound around the pulley 10 is greater than or equal to the minimum radius of curvature of the multi-function cable 9, or 1.48 m. The drive pulley 15 is disposed on the support bearing 12 between the pulley 10 and the drum 8. Now, with reference to FIG. 3, an alternative embodiment of the mobile return device 11 will be described in more detail. . Similar items are designated by the same reference numbers. In this second embodiment, the pulley 10 is unchanged and the support bearing 12 also. On the other hand, the multifunction cable 9 is stretched substantially horizontally from the top of the drum 8 towards the bottom of the pulley 10 around which it wraps around an almost complete circle with a radius of curvature identical to the radius of the pulley 10. Thus, the multi-function cable 9 is returned from a horizontal position to a vertical position in order to be able to penetrate into the well 6 which is vertical via an orifice formed in the support bearing 12 on the side of the support bearing. 12 which is fixed to the plate 2. The drive pulley 15 is disposed on the support bearing 12 in front of the pulley 10 at the rear end of the support bearing 12 in order not to hinder the passage of the multifunction cable 9 by the orifice. Now that the rolling platform 1 carrying all the elements necessary to introduce into a vertical shaft 6 a heating tool 20 suspended on a multifunction cable 9 has been described, the structure of the multifunction cable 9, the connector 21 and the heating tool 20 will be described in more detail.

Figure 10 schematically shows an assembly operation of the multifunction cable 9 and the heating tool 20 via the connector 21 to allow operations in the well 6. The heating tool 20 is first introduced into the head well 22 of the well 6 with the crane 14. The wellhead 22 is equipped with a Blow Out Preventer (BOP) 25 which prevents the return of material that may overflow the well 6. To facilitate the attachment of the heating tool 20 on the connector 21, a temporary holding system 23 is used. For example, the system 23 is in the form of a fork whose teeth hold the heating tool 20. Thus, the heating tool 20 has an accessible end out of the earth and an end inside the well. 6 and is positioned vertically so as to descend into the well 6, while the temporary holding system 23 prevents it from being driven by gravity in the well 6. The operator can then fix the connector 21 on the heating tool 20. The connector 21 is detachable so that the reverse operation is possible. When the connector 21 is fixed on the heating tool 20, the operator can remove the system 23 and the heating tool 20 is then suspended by the multifunction cable 9 which carries its weight. Then, the operator can activate the rotation of the drive pulleys 15 in order to lower the heating tool 20 by delivering a controlled length of multifunction cable 9 at a controlled rate from the control booth 19.

The mobile return device 11 according to the invention is particularly advantageous in terms of safety, compared to previous systems for passing a casing from horizontal to vertical on a derrick. Indeed, the heating tool 20 is positioned vertically and then only fixed to the multifunction cable 9 already verticalized by the pulley 10. Now, with reference to Figures 5 to 9, the structure of the multifunction cable 9 and the connector 21 will be described in more detail.

As shown in FIG. 5, multifunction cable 9, of diameter 25 mm and length 1500 m, comprises support ropes 32 and power supply ropes 33 integrated in cross-linked polyethylene insulating plastic allowing insulation up to 90 °. C. The support ropes 32 are three in number as are the power supply ropes 33. The support ropes 32 are arranged alternately with the power supply ropes 33 inside the multifunction cable 9, so that their centers form a hexagon on the cross section of the multifunction cable 9 shown in FIG. 5.

The multifunction cable 9 is resistant to supporting its own weight, 1T / km, and support additionally the weight of the heating tool 20, for example up to 400 kg.

The power supply ropes 33 are copper XLPE R90 conductive leads supporting 1000 volts covered with an outer sheath of XLPE. Their outer diameter is 6mm.

The support ropes 32 are intended to support the weight of the heating tool 20. The power supply ropes 33 are intended to supply the heating tool 20 electrically from the diesel generator 18 and to transmit the information acquired by the heating tool 20 to the control booth 19, and to transmit the control instructions of the control booth 19 to the heating tool 20.

As shown in FIG. 4, the connector 21 is composed of several pieces of steel of revolution of axis x: a rigid tubular piece 26, an outer sleeve 27, an inner sleeve 29, a piece for stopping the traction lines 28 and a female connector 30.

The outer sleeve 27 has a tube 36 and a flange 37. The end of the multifunction cable 9 is surrounded by the rigid tubular piece 26 which cooperates with the tube 36 of the outer sleeve 27 through O-rings 35 ensuring the sealing of the device. The pull-wire stopping piece 28 is a part comprising a tubular part for receiving the multi-function cable 9 and a perforated solid part to provide through holes for the three support ropes 32 and the three power supply ropes 33 The orifices 40 dedicated to the support ropes 32 are slightly frustoconical and the end of the traction ropes 32 is distressed and embedded in the resin inside these dedicated frustoconical orifices 40, in order to ensure the strength of the binding between the multi-function cable 9 and the stop part of the traction cables 28.

The stop piece of the traction lines 28 is connected to the rigid tubular piece 26 by means of a thread 38 present on the end of the rigid tubular piece 26. The threading 26 is a male thread, and the threading 38 is a female thread.

The inner sleeve 29 has a head in the form of a narrowed ring. Thus, the inner sleeve 29 has an outer shoulder 45 and an inner shoulder 42. The flange 37 of the outer sleeve 27 has an inner shoulder 39 which cooperates with the outer shoulder 45 of the head of the inner sleeve 29. The shoulder internal 42 of the inner sleeve 29 cooperates with an outer shoulder 46 of the stop piece of the traction lines 28. The inner sleeve 29 further has at its other end a thread 43 which is screwed into the head of the female connector 30.

Thus, the female connector 30 is fixed to the inner sleeve 29 which is fixed to the stop piece of the traction lines 28 which is screwed into the thread 38 of the rigid tubular piece 26. The rigid tubular piece 26 and the multifunction cable 9 are arranged to ensure their tightness.

Furthermore, the head of the heating tool 20 is screwed into a thread 44 of the outer collar of the outer sleeve 27 which is in abutment with the inner sleeve 29 via the respective shoulders 39 and 45. The inner sleeve 29 is itself in abutment with the stop piece of the traction cords 28 via the respective shoulders 46 and 42. Thus, the load of the heating tool 20 is transferred to the traction cords 32. heating tool 20 comprises a male connector 31 which has on its upper part three plugs intended to connect in the three sockets 41 of the female connector 30 to allow the power supply via the power supply cables 33. On the 4, to the right of the male connector 31, the heating tool 20 comprises a heating circuit not shown. This heating circuit makes it possible to heat by induction. This heating circuit is electrically powered by the power supply cables 33. The heating tool 20 is for example a MxL Induction tool provided by the company MADIS xL Ltd., Calgary, Alberta, 10 centimeters in diameter over 10 meters long configured to electromagnetically heat a subsurface zone of the oil well 6 to melt the frozen petroleum residues and reactivate the production of the well 6.

In one embodiment, the heating tool 20 is assembled with several other tools, for example temperature and pressure sensors. The use of the verb "to include", "to understand" or "to include" and their conjugated forms does not exclude the presence of other elements or steps other than those set out in a claim. The use of the indefinite article "a" or "an" for an element or a step does not exclude, unless otherwise stated, the presence of a plurality of such elements or steps.

In the claims, any reference sign in parentheses can not be interpreted as a limitation of the claim.

Claims (10)

1. mobile intervention unit on well comprising: a rolling platform (1), a cable storage device comprising a support frame (4) fixed on the platform (1), a drum (8) pivotally mounted on the frame a support and a motor (15) coupled to the drum for driving the drum in rotation in both directions, the pivot axis of the drum extending in a transverse direction of the rolling platform, a movable return device (11), the deflection device comprising a support bearing (12) and a return pulley (10) pivotally mounted on the support bearing (12), the deflection device (11) being movable between a storage position (13) in which the deflection device (11) is placed at a predetermined position on the rolling platform, and a service position in which the pivot axis of the return pulley extends parallel to the pivot axis of the reel, characterized in that what unites mobile interventional well comprises in addition: an induction heating tool (20) intended to be lowered into a wellbore (6) for heating an underground layer, a multifunctional cable (9) at least partially wound on the drum (8), the multifunctional cable having at least one support rope (32) and at least one power supply cord (33), a first end of the multifunctional cable carrying a connector (21) for detachably connecting the cable (9) multifunctional to the induction heating tool (20), and a handling device (14) mounted on the platform, the handling device comprising a motorized arm adapted to move the return device (11) between the position storage (13) and the operating position in which the mobile return device is placed in alignment with the rolling platform beyond a longitudinal end of the platform roulan te to be vertical to the wellbore (6) where the induction heating tool (20) is to be lowered. Mobile unit according to claim 1, wherein the support frame (4) of the cable storage device (8) is located in a forward longitudinal portion of the platform (1) and the handling device (14) is mounted. in a rear longitudinal part of the platform, the service position of the mobile return device being located beyond a rear longitudinal end of the platform. Mobile unit according to claim 1 or 2, wherein the rolling platform (1) has a horizontal upper support surface, the pivot axis of the drum (8) and the pivot axis of the return pulley (10). ) in the service position being located above the support surface. Mobile unit according to any one of claims 1 to 3, wherein the support frame (4) and the drum (8) of the cable storage device comprise contact elements held in sliding electrical contact during the rotation of the reel, the multifunctional cable having a second end coupled to the contact member of the reel for receiving electrical power supply through the contact elements. 5. Mobile unit according to claim 4, further comprising a generator (18) arranged on the platform and connected to the contact element of the support frame to provide the electrical power supply through the contact elements. 6. Mobile unit according to any one of claims 1 to 3, wherein the drum has an inner cylindrical core (24) for winding the multifunctional cable (9) into at least one inner layer resting on the inner cylindrical core and a shell removable cylindrical outer member (124) adapted to be arranged around the inner cylindrical core coaxially with the inner cylindrical core (24) for winding the multifunctional cable (9) into at least one outer layer resting on the outer cylindrical shell (124). 7. Mobile unit according to claim 6, wherein the drum (8) further comprises two end flanges (25) arranged at the two axial ends of the inner cylindrical core (24) and extending radially projecting from the core. internal cylindrical, the outer cylindrical shell (124) being formed of a plurality of plates having an arcuate profile and having two longitudinal ends respectively attachable to the two end flanges of the drum. Mobile unit according to any one of claims 1 to 7, wherein the induction heating tool (20) comprises a connection head having a threaded cylindrical housing and electrical connection pins located at the bottom of the threaded cylindrical housing. , the connector comprising a threaded outer sleeve (37) adapted to be screwed into the threaded cylindrical housing of the connection head to take up the weight of the tool (20) and a female electrical connector (30) adapted to cooperate with the pins electrical connection means located at the bottom of the cylindrical housing to establish an electrical connection between a heating circuit of the induction heating tool and said at least one power supply cord (33) of the multifunctional cable. 9. Mobile unit according to any one of claims 1 to 8, wherein the multifunctional cable (9) has a length greater than 1000 m, an outer diameter greater than 20 mm and a minimum permanent radius of curvature greater than 140 mm, and wherein the drum has a diameter greater than 3m. 10. A method of operating a mobile unit according to any one of claims 1 to 9, comprising: arranging the rolling platform (1) near the head (22) of a wellbore (6) where the induction heating tool (20) is to be lowered, the return device (11) being in the storage position (13), introducing the induction heating tool into the wellhead with the motorized arm (14) of the handling device to an intermediate position in which the connection head of the induction heating tool remains outside the wellhead, attaching the induction heating tool to the wellhead in the intermediate position by means of a static fixing device (23), moving the motorized arm so as to release the space between the reel (8) and the return pulley (10), placing the deflection device (11) ) in the service position using the motorized arm (14) of the handling device, engage the multifunctional cable (9) on the deflection pulley (10) to bring the connector (21) close to the connection head of the induction heating tool, connect the connector to the induction heating tool connection head, disengage the induction heater from the static fixture to suspend the induction heating tool from the multifunctional cable, and lower the induction heating tool into the wellbore using multifunctional cable.