Well bottom tool for removing sections of metal piping.

Abstract

WELL-DOWN TOOL FOR REMOVING METAL PIPE SECTIONS. A well-down tool for removing metal pipe sections, said well-down tool comprising at least one conductive element arranged to corrode a metal pipe section using an electrolytic process, said conductive element being made of electrically conductive material, an apparatus for establishing a connection to the metal pipe, and a source of electrical power.

Description

49 Well bottom tool for removing sections of metal piping. Field of invention

[001] The present invention relates to a downhole tool to be used for corroding long entire sections of metal piping in order to open a window in this metal piping without the use of a drilling rig. Fundamentals of the invention

[002] Standards for well integrity in drilling and well operations require that, when a well is permanently abandoned, the barriers placed in the well to prevent leaks extend across the entire cross-section of the well. The purpose of the plug or cross-section barrier is to ensure isolation from permeable formations, reservoirs, and other sources of inflow.

[003] Currently, this requirement is met by cutting and extracting the tubing and inner tubing in one region of the well, followed by the placement of a cement plug, which can then extend from the formation on one side to the formation on the other side of the well. This operation can be problematic because the inner tubing string can become stuck due to particle settling. Multiple cutting and extraction operations may be necessary to remove the inner tubing. Traditionally, cutting and extracting the inner tubing is done with a drilling rig. Performing this operation can therefore be time-consuming, expensive, and can produce a considerable amount of CO2, especially in subsea wells.

[004] In order to reduce the considerable environmental footprint and the high costs associated with permanent P&A operations, the service industry has been challenged to find alternative ways to open a transverse window in the inner tubing and to set and verify permanent transverse barriers in the well without the use of a probe. Petition 870260033280, dated 10 / 04 / 2026, page 11 / 164 / 49

[005] The invention offers a new method for opening the cross-section window in the inner tubing without the use of a probe using electrical power to accelerate the dissolution or corrosion of long sections of the inner tubing or metal tubing.

[006] The method described here is based on the use of an electric current to stimulate a non-spontaneous reaction in the metal pipe in order to transform the pipe material back to its original condition. This process is carried out using an electrochemical cell comprising an external power source, a conductive solution or electrolyte, and two electrodes (anode and cathode). The cathode is part of the invented downhole tool, which can be operated and powered from the surface via a drilling cable or from a downhole hydroelectric power source or a downhole battery. The electrolyte is an electrically conductive solution and may comprise water or brine already present in the well (a solution with a high salt concentration). The anode is the metal pipe in which a window is to be opened. Description of the state of the art

[007] US 4144936 A describes an apparatus for milling metal or cutting the upper ends of pipes and inner tubing in drilling operations or in abandoning and plugging a well. The tool is for cutting the pipes and inner tubing using electrochemical machining or milling. It includes radially movable electrically conductive elements, which form the cathodes of an electrochemical machining operation for metal removal. The tool element additionally includes an abrasive material (cutting element) so that it can mechanically cut or mill through the cement layers between the inner tubing. An electric current is applied through the tool and adjacent pipe or inner tubing, and saltwater is circulated around the tool and the inner wall of the inner tubing and serves as an electrolyte. Petition 870260033280, dated 10 / 04 / 2026, page 12 / 164 / 49

[008] The subject matter of the invention differs from the description in US 4144936 A, in that the invention corrodes entire long sections of pipes and tubing using a downhole tool that is powered by a downhole power source, such as a battery, or connected to the surface via a cable. In contrast, the system described in US 4144936 A achieves a cut through the inner tubing using a powered downhole apparatus connected to the surface via a hollow drill string. It is also necessary to subsequently use a drilling rig to extract this inner tubing. By corroding entire long sections of inner tubing using the downhole tool described herein, there is no need to extract this inner tubing to meet the requirements for plugging and abandoning oil and gas wells.Therefore, the invention allows a window to be opened in the internal piping without using equipment, substantially reducing cost and CO2 emissions compared to probe-based methods.

[009] WO 2012 / 170806 A1 describes a double-column section milling tool, which includes a cutting block deployed in a single pass in an axial recess in a tool body. The cutting block is configured to extend radially outward and retract radially inward toward the tool body. The cutting block is further configured to remove a cement layer in a wellbore. The milling tool is deployed in a tool string and rotated in the wellbore so that the blades make a circumferential cut in the metallic inner pipe string. The tool string is then driven to the bottom of the well while rotation continues so as to axially mill the inner pipe string to the desired length.

[0010] US 2015 / 101812 A1 describes a double internal pipe window milling cutter for use in a wellbore that includes a Petition 870260033280, dated 10 / 04 / 2026, p. 13 / 164 / 49 tubular housing and a plurality of eccentrically arranged cavities formed in one wall thereof and an arm disposed in each cavity. Each arm has a body portion and a blade portion that extends from an outer surface of the body portion and is movable between an extended and a retracted position. The milling cutter additionally includes cutters disposed along each blade portion and a block disposed in each cavity and connected to the housing. The milling cutter additionally includes an actuator to extend the arms towards the internal tubing.

[0011] The subject matter of the invention differs from the description in WO 2012 / 170806 A and US 2015 / 101812 A1, in that the invention uses electrolysis as the primary method for corroding the inner tubing or metal piping.

[0012] WO 2016 / 048157 A1 describes two electrochemical methods for removing iron-containing inner tubing from a wellbore as part of a plugging and abandonment procedure. The first method uses the outer surface of a conductive fluid line as a cathode. The fluid line is connected to an electrical current source and to a tank containing electrolyte located at the surface. The fluid line is placed between two temporary plugs. These plugs are placed at the top and bottom of the interval from which the iron-containing tubing is to be removed. A conductive electrolyte is then pumped through the fluid line while very high electrical currents from the surface are applied to this fluid line. The electrolytic process will occur in the electrolyte-containing interval between the two plugs, resulting in the removal of the iron-containing inner tubing between the two plugs.

[0013] The second method also uses the outer surface of a conductive fluid line as a cathode, through which very high electric currents are applied from the surface. In this second method, the fluid line is partially electrically conductive and partially insulated with Petition 870260033280, dated 10 / 04 / 2026, page 14 / 164 / 49 a non-conductive coating. The electrically conductive section of the fluid line is placed adjacent to the internal piping containing iron to be removed.

[0014] The subject matter of the invention differs from the description in WO 2016 / 048157 A1, in that the invention corrodes long entire sections of pipes and internal tubing using a downhole tool that is powered and connected to the surface by means of a cable. The downhole tool may contain a power unit that allows the electrical current to the cathode to be transferred through a highly conductive cable in the form of high voltage / low current to be subsequently converted back to high current / low voltage. This is much more efficient than providing high current directly to a long fluid line or pipe, in which case much of the electrical current will be dissipated as heat before reaching the section comprising the cathode.

[0015] Another difference is that while the system described in WO 2016 / 048157 A1 uses heavy fluid lines as cathodes that require a rig or at least a reel tubing unit to be operated, the invented downhole tool can be operated with drill cable equipment, making it more efficient and environmentally friendly and allowing a plugging and abandonment operation to be completed without a rig.

[0016] The downhole tool described here is capable of ensuring bottom-to-top internal tubing removal as well as cathode centering. Where the parts of the internal tubing closest to the top of the wellbore are dissolved first, this can result in portions of the internal tubing becoming electrically isolated so that they do not continue to dissolve, therefore a bottom-to-top removal of the internal tubing is advantageous, as is a centered cathode resulting in uniform dissolution of the internal tubing in a radial direction. Petition 870260033280, dated 10 / 04 / 2026, page 15 / 164 / 49

[0017] New methods for optimizing power consumption during electrolysis (such as using different cathode surface shapes) are described here. None of these descriptions are described in WO 2016 / 048157 A1.

[0018] According to a first aspect of the present invention, a downhole tool is provided for removing sections of metal piping, said downhole tool comprising: one or more conductive elements arranged to corrode a section of metal piping using an electrolytic process, said one or more conductive elements being formed of electrically conductive material, an apparatus for establishing a connection between one or more conductive elements and the metal piping, and a power unit configured to provide an electric current to one or more conductive elements. The power unit may be configured to carry or relay current from the surface or from a battery to the conductive elements and, in some examples, may convert the supplied current as described in more detail below.

[0019] In embodiments, one or more conductive elements are made of electrically conductive material, such as steel, stainless steel, aluminum, copper, titanium, graphite, nickel, or another alloy or coating that reduces the overvoltage between the conductive elements and an electrolyte.

[0020] In modalities, at least one main conductive element is placed centrally in the tool.

[0021] In embodiments, several conductive elements are coupled to the power unit and these conductive elements are mounted on expandable rails configured to move them closer to or toward and away from the metal piping. In embodiments, several conductive elements are coupled to the power unit and these conductive elements are Petition 870260033280, dated 10 / 04 / 2026, page 16 / 164 / 49 mounted on expandable rails configured to move them in a direction perpendicular to the longitudinal geometric axis of the metal pipe.

[0022] In embodiments, the surface of one or more conductive elements is molded with patterns of notches or grooves.

[0023] In embodiments, the surface of one or more conductive elements comprises longitudinal grooves or helical grooves or combinations thereof.

[0024] In embodiments, the surface area size of the conductive element is between 0.8 and 4 times the internal surface area of ​​the metal tubing.

[0025] In embodiments, the tool comprises one or more non-conductive spacers that are configured to rest against the inner surface of the metal pipe during the corrosion process, and wherein at least a portion of the tool is configured to rotate so that the spacers move against the pipe surface.

[0026] In embodiments, one or more conductive elements comprise the non-conductive spacers.

[0027] In embodiments, non-conductive spacers provide a clearance of 0.05 mm to 30 mm between one or more conductive elements and the metal tubing.

[0028] In modalities, at least a portion of the tool is configured to rotate back and forth in an oscillating motion.

[0029] In embodiments, the conductive elements are designed to overlap or contain additional conductive elements that reduce the surface clearance caused by the expanding rails approaching the metal pipe, which may be by the expanding rails moving perpendicular to the longitudinal geometric axis of the metal pipe.

[0030] In modalities, the power unit is configured to convert a low current / high voltage input from a source of Petition 870260033280, dated 10 / 04 / 2026, page 17 / 164 / 49 power in a high current / low voltage output for provision to the conductive elements.

[0031] In some modes, the said output electrical current is DC or pulsating current and may contain high levels of electrical noise.

[0032] In modalities, the input and output of the power unit are electrically isolated from each other.

[0033] In modalities, the input to the power unit is between 400 and 3,000 volts and the output current of the power unit is between 0 and 15,000 Amps.

[0034] In embodiments, the power unit comprises one or more power modules that are connected to one or more conductive elements through the same common conductors.

[0035] In embodiments, the power unit comprises more than one power module and the tool comprises more than one conductive element, and each of the power modules is independently connected to a different of the conductive elements.

[0036] In embodiments, the power unit comprises one or more power modules and the conductors connecting the power modules to the conductive elements are placed within the main chassis of the downhole tool.

[0037] In embodiments, the conductive element, or a composite element comprising more than one conductive element, has a smaller diameter at an upper end and a larger diameter at a lower end.

[0038] In embodiments, the conductive element or a composite element comprising more than one conductive element has a truncated conical shape.

[0039] In some embodiments, the conductive elements may be brought close to the metal tubing. In some embodiments, the conductive elements Petition 870260033280, dated 10 / 04 / 2026, page 18 / 164 / 49 can move in a direction perpendicular to the longitudinal geometric axis of the wellbore, independently of each other.

[0040] In embodiments, the conductive elements may move closer to the metal tubing to form a frustoconical composite conductive element, and the end of said frustoconical composite conductive element with the smaller radius is closest to the apparatus to establish a connection with the metal tubing. In embodiments, the conductive elements may move in a direction perpendicular to the longitudinal geometric axis of the wellbore to form a frustoconical composite conductive element, and the end of said frustoconical composite conductive element with the smaller radius is closest to the apparatus to establish a connection with the metal tubing.

[0041] In some forms, one or more conductive elements are configured to rotate continuously.

[0042] In some forms, one or more conductive elements are configured to rotate back and forth in an oscillating motion.

[0043] In embodiments, the conductive elements are shaped to avoid sharp edges, and in which the grooves formed on the surface of the conductive elements have a sinusoidal cross-sectional profile.

[0044] In some forms, the downhole tool is submerged in an electrolyte having a salt concentration between 2 and 30% by weight.

[0045] In embodiments, the tool comprises a device configured to obtain output current measurements from the power unit and the measurements are used to monitor corrosion of the metal piping.

[0046] In modalities, the tool is configured to be moved during the corrosion process from a deeper position to a shallower position in the well. Petition 870260033280, dated 10 / 04 / 2026, page 19 / 164 / 49

[0047] In embodiments, one or more conductive elements each comprise non-conductive spacers providing a clearance of 0.05 mm to 30 mm between the conductive element and the metal tubing.

[0048] In embodiments, the tool comprises components to actuate the circulation of fluid around the conductive elements and the power unit.

[0049] In modalities, the components are integral with the conductive elements.

[0050] In embodiments, the components for actuating fluid circulation are made of non-conductive abrasive material and are used as abrasive or milling elements, said abrasive elements are shaped to actuate fluid circulation.

[0051] In embodiments, the tool additionally comprises at least one device for providing vibration to the conductive element.

[0052] In embodiments, the tool comprises at least one clamping module comprising a mechanical, hydraulic or electromagnetic device for anchoring and centering the downhole tool and the conductive elements within and to the metal tubing.

[0053] In embodiments, the tool additionally comprises a profiling sensor to record the properties of the formation, cement, metal piping and the environment around the tool.

[0054] In embodiments, the tool further comprises a milling apparatus for cleaning the material deposited on the surface of the inner pipe and the cement behind said inner pipe.

[0055] In embodiments, the downhole tool comprises a mechanism configured to separate the downhole tool's conductive elements in response to user input.

[0056] In embodiments, the downhole tool comprises an apparatus configured to measure the progress of the corrosion process. Petition 870260033280, dated 10 / 04 / 2026, page 20 / 164 / 49 located on or adjacent to the bottom edge of the conductive elements, providing measurements of the thickness of the metal tube at a height that is located between a height of 100 mm above the bottom end of the conductive element and a height of 100 mm below the bottom end of the conductive element.

[0057] In embodiments, the power unit is supplied with power by means of a cable coupled to a surface power source or by a downhole battery or a downhole power generator.

[0058] In embodiments, the downhole tool comprises detection means configured to measure the progress of the corrosion process, the detection means located at or adjacent to the bottom end of one or more conductive elements.

[0059] In embodiments, the detection means are mechanical means comprising one or more protrusions that are movable towards the inner metal tubing and polarized in an outward direction, so that they rest against the section of the inner metal tubing that is being corroded.

[0060] In embodiments, the detection means comprise an ultrasound emitter and detector.

[0061] In embodiments, the detection means are located between 1,000 mm above the bottom edge of one or more conductive elements and 1,000 mm below the bottom edge of the conductive element, more preferably between 500 mm above the bottom edge or end of the conductive element and 500 mm below the bottom edge of the conductive element, and most preferably between 100 mm above the bottom edge of the conductive element and 100 mm below the bottom edge of the conductive element. The bottom edge refers to the bottom edge of the conductive element. If this is not located at the same height Petition 870260033280, dated 10 / 04 / 2026, page 21 / 164 / 49 all around, so the bottom end refers to the lowest point of the bottom edge of the conductor element when located inside the well.

[0062] According to a second aspect of the present invention, a method is provided for cutting a section of internal metal tubing in a wellbore using a downhole tool, the tool comprising one or more conductive elements, the method comprising: locating the downhole tool within and adjacent to a section of internal tubing; electrically coupling the one or more conductive elements to the internal metal tubing and providing an electric current to the one or more conductive elements so that the internal metal tubing is electrochemically corroded; using a sensor on the tool to determine that the internal tubing has been completely corroded along at least a portion of the length of the section of internal tubing; in response to the detection that a portion of the internal tubing has been corroded, moving the tool further up the wellbore to a position adjacent to a new section of internal tubing.The new section of internal piping may overlap the original section of internal piping.

[0063] In embodiments, the method may comprise anchoring the tool at the first location adjacent to the first section of the inner tubing and, in response to the detection that a portion of the first section of the inner tubing has been completely corroded, releasing the anchor and re-engaging the anchor to secure the tool adjacent to the new section of the inner tubing.

[0064] In embodiments, the method comprises detecting that a lower portion of the inner pipe section has been completely corroded. In embodiments, the method comprises locating the tool so that the conductive elements are closest to the inner surface of the inner pipe at a bottom end of the well.

[0065] In modalities, the method comprises locating the tool so that one or more conductive elements are centered within the Petition 870260033280, dated 10 / 04 / 2026, page 22 / 164 / 49 internal piping and aligned with a longitudinal geometric axis of the internal piping section, and the conducting element or conducting elements together have a larger diameter at a bottom end of the well, such that the bottom end of the well of the internal piping section corrodes more rapidly than the top end. Top and bottom are described here in relation to the wellbore (up being a direction towards the surface or the direction the wellbore needs to be followed to reach the surface) and to the tool as it is oriented when located inside the wellbore.

[0066] In embodiments, the detection means are mechanical means comprising one or more protrusions that are movable towards the inner metal tubing, which may represent movement in a direction perpendicular to the longitudinal geometric axis of the inner tubing section and / or the tool and polarized outwards so that they settle against the section of the inner metal tubing being corroded. The extent to which they are able to project or move outwards therefore provides information on how thin the inner tubing section has become or how much of the inner tubing has been corroded. The protrusions may be spaced around the lower circumference of the conductive element or elements and may be polarized outwards using one or more springs.

[0067] In embodiments, the means of detection comprise an ultrasound emitter and detector. The distance to the inner tubing can be determined by means of an echo which will indicate how thin the inner tubing is and how much it has corroded.

[0068] In embodiments, the sensor is located on or adjacent to the bottom edge of one or more conductive elements. In this way, when the bottom portion is corroding more rapidly, this is detected and, by gradually moving the tool upwards from the wellbore to the top, the corrosion can be reached. Petition 870260033280, dated 10 / 04 / 2026, page 23 / 164 / 49

[0069] According to a third aspect of the present invention, a downhole tool is provided for removing sections of metal piping comprising: one or more electrically conductive elements configured to corrode a section of metal piping using an electrolytic process; and a power unit configured to receive a high voltage, low current input and to convert it into a high current, low voltage output for supply to one or more conductive elements.

[0070] In some modalities, the high voltage and low current input power is carried from the surface by means of a drilling cable.

[0071] According to a fourth aspect of the present invention, a downhole tool is provided for removing sections of metal piping comprising: one or more electrically conductive elements configured to corrode a section of metal piping using an electrolytic process; and a power unit configured to provide power to one or more conductive elements, wherein the conductive elements have an outer surface comprising a molded surface having a smooth cross-sectional profile. In embodiments, the molded surface may comprise one or more grooves.

[0072] This additional surface structure increases the surface area of ​​the conductive elements, reducing current density and thus also power consumption. The use of a smooth cross-sectional profile means that sharp regions, which can become high current density regions in use, are avoided. Smoothness refers to the fact that there are no abrupt changes in the angle of the surface, and changes in the surface profile occur gradually (or are continuous) as you move along the surface. Petition 870260033280, dated 10 / 04 / 2026, page 24 / 164 / 49

[0073] In embodiments, the molded surface comprises one or more grooves and the cross-sectional profile of one or more grooves is sinusoidal. In embodiments, the grooves form depressions and peaks on the surface. In an embodiment in which depressions and peaks are present, the depressions and peaks may each have a semicircular cross-sectional profile.

[0074] According to a fifth aspect of the present invention, a downhole tool is provided for removing sections of metal pipe comprising: at least two electrically conductive elements configured to corrode a section of metal pipe using an electrolytic process; and a power unit configured to provide power to one or more conductive elements, wherein the conductive elements are movable in a direction perpendicular to the longitudinal geometric axis of the pipe section when the tool is in place, and the tool comprises a conductive linking section between each of one or more pairs of adjacent conductive elements, such that when the conductive elements move radially, any gap between adjacent conductive elements is filled by the linking section.

[0075] In embodiments, the bonding section or sections comprise a mesh formed by a plurality of bonded conductive elements. The mesh may have a mesh-like structure. In embodiments, the bonding section comprises a thinner portion of one of the conductive elements that lies beneath adjacent conductive elements when the conductive elements are moved radially inward so that the adjacent elements overlap.

[0076] According to a sixth aspect of the present invention, a downhole tool is provided for removing electrically conductive pipe sections comprising: one or more electrically conductive elements configured to corrode a pipe section. Petition 870260033280, dated 10 / 04 / 2026, page 25 / 164 / 49 of metal using an electrolytic process; and a power unit configured to provide power to one or more conductive elements, wherein the tool comprises one or more non-conductive spacers that are configured to rest against the inner surface of the metal tubing during the corrosion process, and wherein at least a portion of the tool is configured to rotate so that the spacers move against the surface of the tubing. The spacers may move against the surface of the tubing to dislodge any reaction products that are deposited thereon. The electrically conductive tubing may be wholly or partially formed from metal.

[0077] In embodiments, spacers are coupled to one or more conductive elements to ensure a minimum clearance between the conductive elements and the metal tubing, and one or more conductive elements are configured to rotate. The conductive elements may rotate forward and backward.

[0078] In modalities, at least a portion of the tool is configured to rotate back and forth in an oscillating motion.

[0079] According to a seventh aspect of the present invention, a downhole tool is provided for removing sections of metal piping, said downhole tool comprising: one or more conductive elements arranged to corrode a section of metal piping using an electrolytic process, said one or more conductive elements being formed of electrically conductive material; an apparatus for establishing a connection between one or more conductive elements and the metal piping; and one or more components for actuating the circulation of fluid around the conductive elements and the power unit. The components may comprise angled vanes that push the fluid in a direction parallel to the tool housing and the wellbore when rotating. Petition 870260033280, dated 10 / 04 / 2026, page 26 / 164 / 49

[0080] In these forms, the components are self-contained components designed to drive fluid circulation.

[0081] In modalities, the components are integral with the conductive elements.

[0082] In embodiments, the components for actuating fluid circulation are made of non-conductive abrasive material and are used as abrasive or milling elements, said abrasive elements are shaped to actuate fluid circulation. Summary of the present invention

[0083] A downhole tool designed to remove single or multiple long sections of metal tubing in a wellbore is described herein. The downhole tool can be operated from the surface or also by means of a control unit located at the subsea installation so that a vessel is only required for installation and retrieval of the tool. The invention involves applying an electric current to electrically conductive elements or cathodes while they are submerged in a conductive brine to corrode surrounding metal tubing. The conductive elements may have a molded or patterned surface to increase the cathode surface area, which will decrease current density and power consumption. The molded surface may comprise one or a series of grooves formed on the surface.Generally, a reduction in power consumption is desirable along with a high current that will increase the rate at which pipe sections can be completely corroded. Molded conductive elements can also be attached to expansion rails that can be activated to position the conductive elements close to the metal pipe to be dissolved. A shorter distance between the conductive elements and the metal pipe will result in a further reduction in power consumption. Petition 870260033280, dated 10 / 04 / 2026, page 27 / 164 / 49

[0084] The shape of the conductive elements can also be such that the removal of the entire metal pipe section is guaranteed. This is achieved by using conductive elements with a substantially conical shape. The area of ​​the metal pipe closest to the conductive element will be removed more quickly than areas with greater distances between them. A conical cathode, with the region of larger diameter located at the bottom of the well, will therefore result in the corrosion of the lower region of the pipe more quickly. The cathode can be frustoconical or it can be stepped so that different diameter regions are provided along the length of the cathode, with the region of larger diameter located at the bottom of the well and the region of smaller diameter at the top.

[0085] The length of the internal pipe section that can be removed depends partly on the size of the conductor elements (although these can be moved progressively into the well to corrode a longer portion of the internal pipe). The size of the conductor elements can vary from a few centimeters to several meters.

[0086] The high levels of electrical current required to efficiently corrode metal tubing can be supplied to the conductive elements directly via a high-current-capacity cable connected to the surface. A high-voltage / low-current AC or DC input (preferably DC) can be supplied to a surface tool power unit via a drilling cable, and this can be converted by the power unit into a high-current / low-voltage DC output for transfer to the tool's conductive element. The required electrical currents are generally DC or pulsating and may contain high levels of electrical noise.

[0087] The invention relates to a coiled cable or pipe drilling tool that is designed to open windows in pipelines. Petition 870260033280, dated 10 / 04 / 2026, page 28 / 164 / 49 internal or other piping in wells that will be capped and abandoned without the need for a probe.

[0088] The invention can also be used to open metal piping for reasons other than plugging and abandoning, for example, for lateral tracking operations with coil piping, conventional corrosion drilling of oriented sections of piping or for crack repair operations.

[0089] The above objects are achieved using a downhole tool to remove sections of metal piping, comprising at least one power unit that can be placed on the surface or at the bottom of the well to provide electric current, at least one conductive element being arranged to corrode a section of metal piping using an electrolytic process, said conductive element in an example being a tube, pipe, plate or a combination thereof that is made of an electrically conductive material and is shaped to optimize power consumption and control the acceleration of corrosion at different positions of the metal piping, and an apparatus for establishing an electrical connection between the downhole tool and the metal piping.

[0090] The downhole tool described here can be placed in a well filled with a conductive brine or electrolyte that will provide the electrical connection between the conductive element and the section of metal pipe to be corroded. In some cases, no additional electrolyte solution needs to be provided.

[0091] The conductive elements of the downhole tool can be made from any electrically conductive material, such as steel, stainless steel, aluminum, copper, titanium, graphite, nickel, or another alloy or coating that reduces the overpotential between the conductive elements and the electrolyte. The conductive elements can be shaped to control the acceleration of corrosion at different positions in the metal tubing and, in Petition 870260033280, dated 10 / 04 / 2026, page 29 / 164 / 49, specifically, to optimize the relationship between the metal tubing and the surface areas of the conductive element. Shaping the surface of the conductive element or cathode can also reduce the tool's power consumption by increasing the cathode surface area and thus reducing the current density. Another method to reduce power consumption is to reduce the distance between the conductive elements and the metal tubing and thus reduce the amount of electrolyte between the conductive elements and the metal tubing. The conductive elements may comprise longitudinal grooves, helical grooves, or a combination thereof. Both configurations will increase the surface area of ​​the conductive element or cathode compared to a smooth cylindrical surface, for example.

[0092] If the downhole tool has a conductive element, it can be placed centrally on the main shaft of the tool. If the downhole tool configuration comprises multiple conductive elements, these can be attached to the main power source by means of expandable rails, to allow the conductive elements to be adjusted for optimal separation of metal pipes of different sizes.

[0093] The downhole tool will be designed to pass through components with the smallest IDs (Internal Diameters) likely to be present in a well. Since the component with the minimum ID may be different from the target metal tubing, the downhole tool, and especially the conductor elements, may have an OD (Outer Diameter) that is smaller or considerably smaller than the ID of the metal tubing. This will affect the amount of electrolyte between the conductor elements and the metal tubing, increasing power consumption. By reducing the distance between the conductor elements and the metal tubing (e.g., by mounting the conductor element or elements on expandable rails), the Petition 870260033280, dated 10 / 04 / 2026, page 30 / 164 / 49 the amount of electrolyte is also reduced, thus decreasing power consumption.

[0094] The conductive elements are fitted with non-conductive spacers that prevent the conductive elements from having direct contact with the metal tubing and therefore causing a short circuit.

[0095] The downhole tool is preferably powered from the surface via a cable, although it can also be powered by a downhole hydroelectric power source.

[0096] When powering the downhole tool via a cable, the high electrical current can be supplied directly from the surface power unit to the conductive elements by means of a high current capacity cable or by supplying a high voltage / low current from the surface via a drilling cable and converting the electrical power to a low voltage / high current DC output by a downhole power unit. Said output electrical currents are preferably direct or pulsating currents and may contain high levels of electrical noise. Said electrical power input may be AC ​​or DC.

[0097] The electrical circuit will be completed by the conductive electrolyte or brine and the connector between the downhole tool and the metal tubing. The negative pole of the power unit will be connected to the conductive element or elements, while the positive pole of the power unit will be connected to the metal tubing via the connector for the metal tubing module.

[0098] The metal pipe connector will be able to conduct the currents supplied by the power unit. This can be achieved using several expandable connectors that will physically connect the metal pipe to the downhole tool. These connectors can be made of highly conductive materials and will be designed to eliminate any electrical welding between the connectors and the metal pipe. The design can Petition 870260033280, dated 10 / 04 / 2026, page 31 / 164 / 49, includes the use of materials such as silver, and the connectors may have different shapes to increase the surface area of ​​the connector.

[0099] The connector for the metal pipe can also be fitted with a release mechanism that can be operated to retract the connectors if the tool fails.

[00100] The downhole tool may contain at least one clamping module comprising a mechanical, hydraulic or electromagnetic device for anchoring and centering the downhole tool. This may also be fitted with an operable release mechanism for disconnecting (e.g., retracting) the connectors should the tool fail.

[00101] The downhole tool may additionally comprise a coupling system for connection, communication and automated control of additional equipment to which the downhole tool is connected. The additional equipment may include downhole tractors, which would allow the downhole tool to be placed at the desired depth.

[00102] The downhole tool may further comprise an operable apparatus for providing vibration to the driving element and other sensors (such as annular pressure sensors or any suitable logging module containing sensors for recording formation properties) and the environment around the tool.

[00103] The downhole tool may additionally comprise a communication unit that provides attachment to a cable and connects the tool to a subsea installation or surface.

[00104] The downhole tool may further comprise a waste collector which may comprise a basket and an operable magnet for recovering solid metallic waste. Petition 870260033280, dated 10 / 04 / 2026, page 32 / 164 / 49

[00105] The downhole tool may also comprise components for driving fluid circulation around the conductive elements.

[00106] The downhole tool may additionally comprise a milling module that can be operated to clean the surface of the inner tubing as well as the cement behind the dissolved inner tubing. Description of the Figures

[00107] The embodiments of the present invention will now be described, by way of example only, with reference to the following Figures, in which: Figure 1 shows one embodiment of the cable-drilled downhole tool according to the invention with a centrally placed conductive element and two clamping elements.

[00108] Figure 2 shows another embodiment of a milling tool according to the invention with several conductive elements in closed position, a clamping element and the connector to the metal pipe also used as a clamp.

[00109] Figure 3 shows another embodiment of a milling tool according to the invention with several conductive elements in an extended position so as to reduce the distance between the conductive elements and the metal tubing.

[00110] Figure 4 shows a diagram of a power unit.

[00111] Figure 5 shows a diagram of a power unit with additional power modules.

[00112] Figures 6 to 8 show different power unit configurations for connecting the power modules.

[00113] Figure 9 shows examples of spacers with different shapes. Petition 870260033280, dated 10 / 04 / 2026, page 33 / 164 / 49

[00114] Figures 10 to 18 show the possible shapes and characteristics of the conductive elements.

[00115] Figures 19 to 22 show alternative solutions for reducing clearance when extending the conductive elements.

[00116] Figure 23 shows an example of caliper measurement.

[00117] Figure 24 shows an example of the optional milling device for removing cement after dissolving the inner pipe.

[00118] Figures 25 to 29 show the different configurations of the power unit for connecting the power modules, including optional through holes to provide flow within the power unit, communicating with or driving components below the power unit. Description of preferred embodiments of the invention

[00119] As seen in Figures 1, 2 and 3, the downhole tool comprises several components. In Figure 1, the tool is shown inserted into a metal pipe 2 of a wellbore, which contains a conductive brine. The tool comprises a surface connection 8, for example, a cable. The clamping elements 5 may be fitted with expandable parts that can apply a force inside the metal pipe 2 to hold and center the tool. An enclosure 17 is provided, which may contain a power unit 7 to convert the electrical power distributed by a surface power source (not shown) into the electrical current required to be distributed to the conductive elements 1,10 and other components.Enclosure 17 may also contain downhole batteries to provide power or an alternative source of electrical power for the downhole tool and conductive elements 1,10 and many of the additional components that may be required to operate the downhole tool. Among many other functions, these additional components may be used to establish communication with the downhole tool, provide downhole hydraulic power, acquire data, etc. Petition 870260033280, dated 10 / 04 / 2026, page 34 / 164 / 49 to control downhole systems and measure environmental conditions and the condition of metal piping or formations surrounding the downhole tool through sensors 9.

[00120] The tool may further comprise a device such as an expandable connector 4 for creating an electrical connection between the downhole tool and the metal pipe 2 and at least one conductive element such as a conductive element or cathode 1. Figure 2 shows various conductive elements 10 and Figure 3 shows said conductive elements 10 expanded so as to reduce the distance to the metal pipe. The conductive elements 10 may also rotate. Said conductive elements 1 and 10 are used to corrode the metal pipe using an electrolytic process.

[00121] Also included in Figure 1 is component 6, like a turbine, which drives the circulation of fluid around the tool to recirculate the electrolyte and assist in the heat transfer from the power unit 7 and the conductive elements 1 and 10 to the electrolyte. Component 6, like a turbine, is placed, for example, above and below the power source 7. Component 37 in Figure 1 is an operable instrument for measuring the diameter of the metal pipe 2, and component 38 is a device that centers the downhole tool below the conductive elements 1 and 10, both optional.

[00122] The spacers 3 are made of non-conductive material and are used to separate the conductive elements 1,10 from the metal tubing 2 to prevent a short circuit. Said spacers are shaped to reduce the contact area with the metal tubing 2, which in turn helps to minimize the current density on the surface of the conductive elements.

[00123] More details of the invention and its components will now be explained. Petition 870260033280, dated 10 / 04 / 2026, page 35 / 164 / 49

[00124] Clamping Elements: The tool will generally comprise at least one mechanical, hydraulic, or electromechanical clamping element 5 that can anchor and center the downhole tool to and within the metal tubing. Said clamping elements may be placed above or below the driving elements (or both). If placed below the driving element, the clamping elements may only be operable to center the downhole tool and not clamp the metal tubing 2. The clamping elements may be fitted with a release mechanism that will retract the connectors in case of tool failure. The downhole tool will normally include at least two clamping elements 5. One of these clamping elements may also act as a connector for metal tubing.

[00125] Connector for metal piping: The tool also contains at least one mechanical, hydraulic, or electromechanical coupling element 4 that electrically connects the downhole tool to the metal piping. Said connector may be placed above or below the conductive elements, but will generally be installed above the conductive elements. The coupling elements 4 for metal piping 2 may be equipped with a release mechanism that will retract the connectors should the tool fail. Said metal piping connector may also anchor and center the downhole tool in the metal piping 2, as seen in Figures 2 and 3, but may be dedicated solely to the electrical connection, as seen in Figure 1. One or more of the clamping elements 5 described above may therefore also act as coupling elements 4 to provide an electrical connection between the metal piping and the tool.

[00126] Power unit: The power unit 7 is generally located within a protective enclosure 17 and comprises, among other components, one or more power converter modules 11 that Petition 870260033280, dated 10 / 04 / 2026, page 36 / 164 / 49 convert the electrical power provided from the power source into the necessary high electrical current.

[00127] The downhole tool receives electrical power from the surface-located power source via wire cable or wire 8, or from a downhole hydroelectric power source, or from a downhole battery. Electrical power may be supplied to the downhole tool as high-current / low-voltage DC power, more preferably as high-voltage / low-current AC power, and even more preferably as high-voltage / low-current DC power.

[00128] By providing high current / low voltage DC power from the surface directly to the conducting elements 1,10, said electric currents may preferably be between 0 and 15,000 Amps, more preferably between 0 and 6,000 Amps, and even more preferably between 0 and 3,000 Amps. This method for providing electric current can be used at depths between 0 and 3,000 meters, more preferably between 0 and 1,000 meters, and even more preferably between 0 and 300 meters. When this method for transferring current to the conducting elements 1,10 is used (i.e., when power is provided directly to the conducting elements from the surface without conversion), a downhole power unit 7 may not be necessary, as the electric current will be provided directly to the conducting element 1,10 and other downhole tool components.However, a downhole power unit 7 can still be used to supply electrical power to other components within the downhole tool.

[00129] The provision of electrical power in the form of high-voltage / low-current AC power will not be further described, as it is very similar to the more preferable high-voltage / low-current DC transfer and conversion method which will be described below. The main differences will be the provision of electrical power in the form of AC voltage and current, in Petition 870260033280, dated 10 / 04 / 2026, page 37 / 164 / 49 instead of DC voltage and current. Therefore, an AC / DC power converter will need to be used instead of a DC / DC power converter to convert the AC power into an output current for input into the conductive elements. Said output electrical current is preferably DC or pulsating current (combination of AC and DC) and may contain high levels of electrical noise. AC current can be supplied instead of direct or pulsating current, but this will reduce the efficiency of the corrosion process. DC current is the most preferable.

[00130] The power provided from a downhole battery within enclosure 17 may be high voltage / low current DC power. The battery or batteries may be used to power the downhole tool components and / or the conductive elements 1,10. This method is preferred when using the downhole tool to open short sections of metal pipe at all operating depths. For longer pipe sections, however, an alternative power source may be required. The tool may be operated with power sources of both types to allow for easy switching between the two.

[00131] It is preferable to provide high-voltage / low-current DC power from the surface to the downhole tool. Generally, a DC voltage between 400 and 3,000 Volts is provided, more preferably between 600 and 1,500 Volts, and even more preferably between 700 and 1,000 Volts. The currents provided can result in available power ranging from 0 to 150 KVA, more preferably between 0 to 20 KVA, and even more preferably between 0 to 15 KVA. This method of providing electrical power from the surface (e.g., via a drilling cable) is preferable for all operating depths.

[00132] The bottomhole power unit 7 is operable to convert high voltage / low current electrical power supplied from the surface into low voltage / high current electrical power for Petition 870260033280, dated 10 / 04 / 2026, page 38 / 164 / 49 provision to conductive elements 1,10 in order to corrode the metal pipe section 2. The current supplied by the power unit 7 to the conductive elements 1,10 may vary between 0 and 15,000 Amps, more preferably between 0 and 6,000 Amps and even more preferably between 0 and 3,000 Amps. Said output currents are preferably DC or pulsating currents and may contain high levels of electrical noise. The voltages of the power unit 7 may be between 0 and 100 Volts, more preferably between 0 and 20 Volts and even more preferably between 0 and 10 Volts. These parameter ranges allow the corrosion rate to be maximized while remaining below the power usage required for the tool.

[00133] Instead of providing a conversion module, the power unit 7 can be constructed with one or more internal DC / DC (or AC / DC) modules 11 which, combined, provide the necessary current levels. This reduces manufacturing costs and unit complexity. Examples of possible embodiments of the power unit are shown in Figures 4 to 8. Figure 4 shows a power unit 7 with six power converter modules 11, while Figure 5 shows a power unit with nine power converter modules 11. These two configurations are preferable; however, any number of power converter modules 11 can be included in the power unit.When multiple power converter modules 11 are used, the outputs from these power converter modules 11 can be transferred individually to individual conductive elements 10, or a combination of two or more conductive elements, via a highly conductive cable, wire, plate or bar 12, 13, 14 as shown in Figures 6, 7, 8. The internal power converter modules 11 can alternatively all be connected to the same highly conductive elements, which can be wires, plates or bars, which are also connected to the conductive elements 1, 10 and the connector to the anode 4. In one embodiment, Petition 870260033280, dated 10 / 04 / 2026, page 39 / 164 / 49 The conducting elements are conducting bars having a rectangular cross-sectional shape 12, as seen in Figure 6. A more preferred cylindrical cross-sectional shape for the elements 13 is shown in Figure 7, and even more preferred is the triangular cross-sectional shape 14 shown in Figure 8. A mixture of different cross-sectional shapes for the bars may also be used. These conducting bars 12, 13, 14 are assembled together with a structure made of or containing electrically insulating material 15 to form the main chassis of the downhole tool. Said conducting elements may also contain through holes 47 as in Figure 27. The through holes 47 may also be positioned in the insulating material 15 as in Figures 25 and 26.The said through holes are intended to accommodate insulated electrical wires, hydraulic lines, or a combination thereof, in order to communicate with or actuate the tool components below the power unit 7. The number of through holes may vary depending on the number of components located below the power unit 7. Figures 28 and 29 also show a through hole 48 through which electrolyte may flow to assist electrolyte circulation within the power unit 7. One or more through holes may be provided and generally extend parallel to the longitudinal geometric axis of the tool housing. The through hole or holes may also potentially provide cooling to the power unit or provide additional cooling to the power unit.

[00134] The components of the power converter module 11 that generate heat can come into contact with the enclosure 17 by means of a highly thermally conductive element 16 to dissipate the heat. In embodiments, the dissipated heat can be used to increase the temperature around the conductive elements 1,10 which will increase the conductivity of the brine and therefore the rate of corrosion. Figures 4 to 8 show the Petition 870260033280, dated 10 / 04 / 2026, page 40 / 164 / 49 thermally conductive element 16, which can extend along all power converter modules 11.

[00135] All modules are placed inside an enclosure 17, which is capable of withstanding the bottom-of-well environment. The DC / DC modules (or AC / DC modules) will also come into contact with said enclosure 17 as a method of transferring heat to the electrolyte, metal tubing 2, and formation. The heat transfer will both cool the electronic components of the internal modules and increase the temperature of the electrolyte. The temperature increase will further increase the conductivity of the electrolyte.

[00136] Power unit 7 and all its modules 11 have galvanic isolation between the input and output. Among other benefits, this isolation will prevent the acceleration of corrosion of the drill cable wire that connects the tool to the surface. This unit will also be able to handle a short circuit caused by the connection of the conductive element 1,10 to the metal tubing 2.

[00137] Power unit 7 can also provide power to the other components of the downhole tool.

[00138] Electrolyte circulation module: the circulation component 6 is used to assist the circulation of electrolyte between the conductive elements 1, 10 and the metal piping 2, as well as the enclosure 17. It can be independent or form part of the expandable conductive elements 10. If component 6 is independent, it can be placed above or below the enclosure 17, as well as above or below the conductive elements 1, 10. It can provide flow rates that are preferably between 0 and 100 liters per minute, more preferably between 0 and 20 liters per minute, or even more preferably between 0 and 10 liters per minute. If the function of driving the fluid circulation is also performed using the expandable conductive elements 10, said expandable conductive elements 10 or portions of them Petition 870260033280, dated 10 / 04 / 2026, page 41 / 164 / 49 The tool or the entire tool will be able to rotate continuously or in an oscillating manner. The fluid circulation will then be aided by the movement of the non-conductive elements 3. The non-conductive elements 3 may also be made of abrasive material and be used as abrasive or milling elements, said abrasive elements having an ideal shape for conducting fluid circulation. Said elements may also function as spacers between the conductive elements and the metal tubing.

[00139] Spacers: The purpose of the spacers 3 is to maintain a physical separation between the conductive elements 1, 10 and the metal tubing 2 to prevent a short circuit. The non-conductive spacers 3 can provide a gap between 0.05 and 20 mm, more preferably between 0.05 and 10 mm, or even more preferably between 0.5 and 2 mm. Said non-conductive elements will be shaped to reduce the contact area with the metal tubing. Figure 9 shows several possible shapes for the spacers 18, 19, 20, and 21. Different shapes and positions for the spacers can be advantageous in different applications. For example, the shape shown in Figure 18 can be used when rotating conductive elements are used to assist in the circulation of the electrolyte. Figure 19 shows a spacer placed at an angle, which increases hydrogen escape between the conductive elements and the metal tubing when the electrolytic process is carried out in diverted wells.The shape of the spacers in Figure 21 has a minimal contact area with the conductive element compared to those shown in Figure 20 and is therefore generally preferable. A combination of spacers of different shapes can be used, but it is preferable that all spacers have the same shape and size. Where multiple conductive elements are used, each can include at least one spacer. The size of the spacers should be kept to a minimum while still providing the function of preventing a short circuit. Petition 870260033280, dated 10 / 04 / 2026, page 42 / 164 / 49 circuit between a conductive element and the piping or internal metal tubing.

[00140] Electrically conductive elements or cathodes 1,10: The function of the conductive elements or cathodes 1 and 10 is to corrode the metal tubing 2 in the wellbore using an electrolytic process. The downhole tool may contain one or more molded conductive elements 1 and 10. The conductive elements are positioned in the center of the well (around or along the longitudinal geometric axis of the wellbore and normally also around and equidistant from the longitudinal geometric axis of the tool itself), and may be formed from many conductive materials, such as, but not limited to, steel, stainless steel, aluminum, copper, titanium, graphite, nickel, or other alloy. The conductive element or elements may be provided with a coating that reduces the overpotential between the conductive elements and the electrolyte.

[00141] The conductive element or elements may also have different shapes which will result, among other things, in a controlled corrosion rate at different positions in the metal piping and in a reduction in power consumption during the electrolytic process, as described in more detail below.

[00142] One of the reasons for controlling the corrosion rate at different positions along metal tubing 2 is to corrode metal tubing 2 located at one end of the tool well bottom (which will normally also be on the opposite side of the tool from electrical connector 4) faster than metal tubing 2 closer to connector 4. This ensures that metal tubing 2 surrounding the conductive element(s) or cathode is, at all times during the corrosion process, electrically connected to connector 4. Failure to control the corrosion rate along metal tubing 2 may mean that sections of tubing that are not yet corroded become isolated due to Petition 870260033280, dated 10 / 04 / 2026, page 43 / 164 / 49 sections closest to the connector will corrode first. These sections of the tubing will lose the electrical connection with the anode 4 connector, which means they will not be completely corroded.

[00143] The preferred methods for controlling the rate of corrosion are: Use of a frustoconical conductive element: Using a frustoconical conductive element 1, as shown in Figure 10, results in a greater volume of electrolyte present between the smaller diameter part of the cone and the metal tubing (which is closer to connector 4 and is on the top part 22 of the tool) than between the larger diameter part of the cone and the metal tubing (which is further from connector 4 and closer to the bottom part 23 of the tool). This diverts more electrical current to the bottom part than to the top part of the metal tubing 2, so the bottom part of the metal tubing 2 corrodes faster than the top portion.

[00144] The preferred truncated conical (or frustoconical) shape has a radius 22 at the top that is between 1 and 50 mm smaller than the radius 23 at the bottom. The difference between the radii at the top and bottom is most preferably between 1 and 10 mm and even more preferably between 2 and 5 mm. The frustoconical shape may have a smooth surface as shown in Figure 10, or it may be formed by a series of cylinders of gradually increasing diameter.

[00145] Additional surface features can be provided on top of the molded conductive element. Figure 11 shows a molded conical conductive element with additional surface grooves.

[00146] The conical form method can also be applied when multiple conductive elements 10 are used. These elements will sit together to form a modular element having a substantially frustoconical shape, the diameter of which can be adjusted using extendable rails as described above. Means can be provided for Petition 870260033280, dated 10 / 04 / 2026, page 44 / 164 / 49 close any gaps between the conductive elements where a larger diameter modular element is required, as described in more detail below.

[00147] Controlled expandable rails: when using multiple conductive elements 10, these can be affixed to expandable rails that will allow adjusting the distance from the outer surface of each conductive element to the metal tubing 2. The expandable rails can also allow adjustment of the angle or shape of the elements. The expansion could be controlled to adjust the separation of the bottom portion of the conductive elements 10 to be closer to the metal tubing 2 than the top part (to configure the modular element as a truncated cone, for example).

[00148] Surface shape: altering the surface shape of the conductive elements 1,10 as shown in Figures 11 to 15 will result in changes in the current density on the outer surface of the conductive elements. The surface can therefore be shaped to adjust the current density on the top and bottom of the conductive element 1, 10 to control the corrosion rate along the length of the conductive elements.

[00149] Figure 11 shows a preferred sinusoidal surface pattern along the length of the conducting element 1,10. The grooves (which can be longitudinal, radial, or helical) increase the surface area of ​​the conducting element, which in turn reduces the current density on its surface and minimizes power consumption. Grooves with a smooth cross-sectional profile, such as a sinusoidal profile, avoid sharp edges that can result in areas of high current density.

[00150] In the example shown in Figure 11, the modular element or single element forms a tapered or conical shape. Figure 12 shows the preferred sinusoidal surface pattern placed across an element. Petition 870260033280, dated 10 / 04 / 2026, page 45 / 164 / 49 conductor 1,10 with a cylindrical shape. Figures 13 and 14 show the preferred sinusoidal surface pattern that forms a helical ridge or filament on the surface of the conductor element 1,10 (which may have any shape, such as frustoconical as in the other examples given above). Where a helical groove is present, the distance between the filaments on the top part of the conductor element 1,10 may be different from those on the bottom part, as shown in Figure 13.

[00151] The elements shown in Figures 10 to 14 can all be frustoconical (tapered) or they can have a cylindrical shape.

[00152] Figure 15 shows a preferred sinusoidal surface shape for grooves on the surface of the conductive element 1,10. An alternative method for controlling the corrosion rate uses different measurements of 24 to 28 at the top compared to the bottom to differentiate the average amount of electrolyte and surface area between the conductive elements 1,10 and the metal tubing 2.

[00153] The shape and materials of the conducting element 1,10 can also influence electrical power consumption. During electrolysis, hydrogen bubbles are formed on the surface of the conducting element 1,10, decreasing the effective surface area of ​​the conducting element 1,10 itself. The bubbles temporarily isolate areas of the conducting element 1,10 from the electrolyte, increasing the overall resistance and therefore increasing the voltage drop and power consumption.

[00154] This effect can also be represented as a function of current density: i=I / A where: i= Current Density, I=Current, A=Area.

[00155] When the effective surface area of ​​the conducting element 1,10 is decreased, the current density in the conducting element 1,10 increases. Higher current densities will result in greater power dissipation in the form of heat. Petition 870260033280, dated 10 / 04 / 2026, page 46 / 164 / 49

[00156] One method to reduce this effect is to increase the surface area of ​​the conductive element or elements 1,10 by machining grooves into its surface as exemplified in Figures 10 to 15. A larger surface area of ​​the conductive element 1,10 compensates for the area lost by bubble formation. A higher density of grooves or notches can be provided in regions of the element that are expected to be particularly susceptible to the effect of hydrogen bubble formation.

[00157] Figure 15 shows one of the preferred surface patterns in which a number of alternating longitudinal semicircular grooves with semicircular ridges are formed on the surface of the conductive element 1,10. The distance 24 between the ridges can be between 1 mm and 20 mm, more preferably between 2 and 10 mm and even more preferably between 2 and 5 mm. The distance 26, which represents a vertical portion (extending radially) of the curve between each groove and peak, can be between 0 mm and 20 mm, more preferably between 0 and 15 mm and even more preferably between 0 mm and 5 mm. The radii 27 and 28 of the semicircular grooves and peaks can be equal or different from each other and, in some examples, can be between 1 mm and 2 mm, although the radius may be outside this range. Distances 24, 25, 26, 27 and 28 may also be different at the top of the conductive element 1.10 compared to the bottom.

[00158] The inclusion of patterns on the surface of the conductive elements 1,10 results in a surface area of ​​the conductive element 1,10 that is larger than the internal surface area of ​​the surrounding metal tubing 2. Figure 16 shows as an example a 100 mm long conical cathode without grooves and with a surface area 29 of 32K mm2 surrounded by a 100 mm long metal tubing 2 with an internal surface area 31 of 36K mm2. The surface area 29 of the conical cathode is 0.9 times the size of the internal surface area 31 of the metal tubing 2. Figure 17, in contrast, shows a 100 mm long conical cathode with Petition 870260033280, dated 10 / 04 / 2026, page 47 / 164 / 49 sinusoidal surface grooves with a surface area 30 of 46K mm2 surrounded by a metal tube 2 of 100 mm length with an internal surface area 31 of 36K mm2. The surface area 30 of the conical cathode is 1.28 times the size of the internal surface area 31 of the metal tube 2.

[00159] The surface area of ​​the conductive element 1,10 is preferably between 0.7 and 4 times the size of the internal surface area 31 of the surrounding metal pipe 2, more preferably between 1 and 2 times and even more preferably between 1.1 and 1.8 times.

[00160] To avoid sharp edges and their associated high current density, the conducting elements 1,10 may also have curved bottom and / or top edges. An example showing curved edges 32 for a cathode with sinusoidal surface slots is shown in Figure 18.

[00161] The length of the conductive element 1,10 is preferably between 1 cm and 10 meters, more preferably between 1 and 5 meters and even more preferably between 1 and 2 meters.

[00162] Other methods for reducing energy consumption are: To increase the conductivity of the electrolyte: by increasing the concentration of ions in the solution, the conductivity will increase and the power consumption will decrease. A preferred method for increasing conductivity is to increase the salt content of the brine in the well. The preferred salt concentration in the electrolyte is between 2 and 30% by weight. The salts contained in the electrolyte may include NaCl, CaCl2, and KCl. A suitable electrolyte could be, for example, seawater with added NaCl.

[00163] Increasing the electrolyte temperature: Higher temperatures increase ion mobility, thus increasing conductivity. The higher the electrolyte temperature, the lower the resistivity and the lower the power consumption. The preferred electrolyte temperature is between 70 and 120 degrees Celsius. The preferred method for maintaining the electrolyte at this temperature Petition 870260033280, dated 10 / 04 / 2026, page 48 / 164 / 49. The desired objective is to transfer heat from the power unit 7, which may be present in enclosure 17, to the electrolyte using a temperature-conducting element 14 coupled to the Power Modules 11 in enclosure 17. The electrolyte can be cooled, if necessary, by recirculating the fluid around the tool using component 6 (or diverting heat from the power unit away from the electrolyte for a time). The electrolyte temperature can be monitored continuously or intermittently, and heating and cooling mechanisms used to correct any temperature drop or rise.

[00164] Controlled downhole tool positioning: Using methods (such as a frustoconical conductor element) to corrode the metal tubing 2 adjacent to the bottom 23 of the conductor element more rapidly than the metal tubing adjacent to the top 22 of the element will result in the total corrosion of the metal tubing at the bottom first. The portion of the conductor element 1,10 where the metal tubing 2 has been completely corroded will then not be surrounded by any metal tubing 2 or, if there is a second metal tube of larger diameter surrounding the inner tubing, it will be further away from said section of the conductor element 1,10. Both situations will result in increased power consumption. Moving the downhole tool above the recently completely corroded metal tubing 2 will keep the conductor element 1,10 fully surrounded by metal tubing 2 and therefore maintain efficient use of electrical power.

[00165] Cathode Material: The Activation Overpotential is the activation energy required to transfer an electron from an electrode to an electrolyte. A higher overpotential will result in higher power consumption. Choosing the right material for the conductive elements 1,10 can therefore help reduce power consumption. Preferred materials for constructing conductive elements may be steel, stainless steel, aluminum, Petition 870260033280, dated 10 / 04 / 2026, page 49 / 164 / 49 copper, titanium, graphite, nickel or other alloy or coating that reduces this overpotential between the conductive elements and the electrolyte.

[00166] Reducing the distance between the conductive element 1,10 and the metal tubing 2: even though the electrolyte surrounding the conductive elements 1,10 is conductive, it still offers some electrical resistance that causes power dissipation in the form of heat. Due to the internal diameter restrictions present in a well, the electrolyte present between the conductive elements 1,10 and the metal tubing 2 can substantially increase power dissipation. The preferred method for decreasing the distance between the conductive elements 10 and the metal tubing 2 is to use mechanical, hydraulic, or electromechanical actuators to move the conductive elements 10 from the center of the downhole tool towards the metal tubing 2. Figures 2 and 19 show examples of various conductive elements 10 in a closed position, while Figure 3 and Figure 20 show the same or similar conductive elements 10 extended to reduce the distance to the metal tubing.

[00167] One consequence of being able to move the conductive elements 10 from a closed position to an extended position is that, when extended, there will be areas of metal tubing 2 that will not be covered by the conductive elements 10. These gaps 34 in the covering can be seen in Figure 21 and will cause the metal tubing 2 to corrode unevenly.

[00168] To minimize this coverage gap and its effects, the following methods can be used: Overlapping cathode plates: the conducting elements 10 are designed to overlap each other. One possible method for providing overlapping conducting elements is shown in Figures 19 and 20, where each of the conducting elements 10 contains an extension 33 that projects from an edge causing the conducting elements 10 to overlap and Petition 870260033280, dated 10 / 04 / 2026, page 50 / 164 / 49 reduces the gap 34. The protruding portion lies below (or above) an adjacent element when the diameter of the composite element is reduced. The extension 33 may be made of a flexible conductive material and may also include surface features such as surface grooves to increase the surface area of ​​the extension.

[00169] Conductive network: a flexible conductive network 35 connects the different conductive elements 10. An example of said network is shown in Figure 22 where the network is made of small interconnected conductive rings. The network can be made of interconnected components with more complex shapes in order to increase the surface area of ​​the network. The network can be made of any of the preferred conductive materials and preferably will be of the same material as the conductive elements 10.

[00170] Rotating conductive elements: the conductive elements 10 can be configured to rotate so that the gap is not constantly located adjacent to an area of ​​the metal tube. This will therefore average the position of the gap in the tubing, resulting in uniform corrosion of the metal tubing 2. The rotation can be either continuous or oscillating. The conductive elements 10 can rotate independently or together with the entire tool, the power unit or some of its modules. Rotation can occur only while electrical power is applied to the conductive elements 10 or also when no electrical power is applied. In the latter case, current can be applied intermittently to provide the torque of rotation of the conductive elements in a certain amount each time current is applied and the elements can continue to rotate even when current is not being applied.

[00171] There are many other possible reasons for uneven corrosion of metal piping 2. One reason is that the metal piping may have an oval shape instead of a circular one due to manufacturing quality or Petition 870260033280, dated 10 / 04 / 2026, page 51 / 164 / 49 deformation over time. Other reasons may involve the effects of non-conductive hydrogen bubbles. These bubbles displace the conductive electrolyte, reducing the available electrical path between the conductive elements 10 and the metal tubing 2, increasing the overall resistance. In inclined wells, the hydrogen bubbles produced during the electrolytic process will tend to float and accumulate on the upper part of the metal tubing 2. Differences in the concentration of hydrogen bubbles around the metal tubing 2 will result in different resistivities in the electrolyte around said metal tubing 2 and, therefore, more corrosion occurs on the side of the metal tubing 2 exposed to the less resistive electrolyte. In non-vertical wells, the lower side of the metal tubing 2 may corrode more rapidly than the upper side.

[00172] Methods for minimizing uneven corrosion of metal piping 2 include: Movable conductive elements independently: each of the expandable rails of the conductive elements 10 (or other means for adjusting the position of the elements) can be adjusted independently of each other, which can allow adjustment of the distance to the metal pipe 2 to compensate for uneven corrosion due to deformations of the metal pipe 2, or the effects of the accumulation of non-conductive byproducts in wells with high inclination. To assist in this process, the current outputs of each power module 11 connected independently to each conductive element 10 are measured. These measurements are then used to indicate the ideal separation for each conductive element 10. The adjustment can be performed automatically in response to current measurements indicating uneven erosion, or manual adjustments can be made from a user interface module on the surface.

[00173] Centering elements: for longer conductive elements 1.10, softening may occur towards the bottom end, Petition 870260033280, dated 10 / 04 / 2026, page 52 / 164 / 49 especially in non-vertical wells. This deformation of the conductive element 1,10 will result in faster corrosion on the underside of the metal pipe 2. To minimize this effect, a centering element 37 can be placed below the conductive element 1,10.

[00174] The said centering element may contain non-conductive expandable arms 38 with components 39 that assist in positioning the downhole tool at the desired depths. The centering element will reduce drag by reducing the contact area while the downhole tool is changing position within the well.

[00175] Monitoring the progress of metal pipe corrosion provides the necessary information to efficiently position the downhole tool in the ideal location and to precisely terminate the corrosion process in order to minimize any damage to the larger diameter metal pipe surrounding the target metal pipe 2. Several methods are available to monitor the corrosion process: Electrical measurements: Corrosion of metal pipe 2 will cause the distance between conductive element 1 and metal pipe 2 to increase. Greater distances will cause the voltage to increase. Furthermore, where sections of the metal pipe are completely corroded, conductive element 1 will have no surrounding metal pipe, further increasing the voltage drop. Monitoring the voltage will give an indication of the progress of the corrosion process.

[00176] Expandable conductive elements: when using expandable conductive elements 10, the conductive elements 10 will expand further as the wall thickness of the metal pipe 2 decreases. Measuring the position of the expandable conductive elements will provide information on the progress of corrosion. Petition 870260033280, dated 10 / 04 / 2026, page 53 / 164 / 49

[00177] Measuring the distance to the metal pipe: a measuring device can also be used to measure the thickness or distance to the metal pipe 2.

[00178] The said device may preferably use ultrasonic measuring means to measure the distance to the metal pipe 2 or its thickness. The time required for the return of the reflected signal will provide information about the distance to the metal pipe, because an increase in distance will be directly related to the amount of corroded material and therefore to the thickness. No reflected signal or a delayed reflected signal from the additional structure in the well will indicate that the metal pipe is completely corroded at the measuring depth. It is even more preferable to use an apparatus with non-conductive expandable strips 37 for the measurement. The expandable elements 40 may be located around the circumference of the tool at the lower end of the conductive elements. These may include a spring to polarize them in the extended position.A sensor is associated with each element and can determine whether the element is pushed through the metal tubing or fully extended, or it can be operated to determine the extent to which the elements are extended and thus the current width of the metal tubing at the depth of the elements. When the region of the metal tubing adjacent to the elements is completely corroded, the elements will be fully extended and their extension will be detected by the sensor. In response, the tool can be raised into the well until the elements are pushed through the metal tubing again, at which point the conductive elements are completely surrounded by the metal tubing again and efficient corrosion can begin anew.

[00179] A preferred position for the device is at or near the bottom of the conductive element 1,10, as seen in Figure 23. Said device will preferably provide measurements of the width or absence of the metal tubing 2 located 100 mm above the bottom end. Petition 870260033280, dated 10 / 04 / 2026, page 54 / 164 / 49 of the conductor element 1 to 10 to 100 mm below the bottom end 42 of the conductor element 1,10. More preferably, the instrument will provide measurements of the width or absence of metal tubing 2 located between 50 mm above the bottom end 41 of the conductor element 1 and 10 to 50 mm below the bottom end 42 of the conductor element 1,10. Even more preferably, the instrument will provide measurements of the width or absence of metal tubing 2 located between 20 mm above the bottom end 41 of the conductor element 1,10 and 20 mm below the bottom end 42 of the conductor element 1,10. The location of the measurement will result in an operational advantage by providing immediate information on the progress of corrosion and where the metal tubing is being corroded first.This information can be used to adjust the position of the tool within the well (i.e., moving it up into the well so that the conductive elements are completely surrounded by non-corrosive metal tubing) or to adjust the position of the conductive elements to compensate for uneven corrosion, if desired.

[00180] Generally, measuring devices are configured to provide an indication of whether the portion of the metal tube adjacent to the bottom end of the conductor elements has been completely corroded. If so, then the tool can be moved upwards into the wellbore in response. If measuring devices are not present or are not available for use, the tool can be moved upwards into the wellbore based on an estimated time to completely corrode an area of ​​the metal tube adjacent to the bottom of the conductor element. The tool can also be raised continuously or periodically according to predefined times.

[00181] The corrosion process is therefore carried out in stages, with the tool being lifted into the well before each stage in order to provide corrosion from the bottom to the top of the pipe section. This ensures a connection Petition 870260033280, dated 10 / 04 / 2026, page 55 / 164 / 49, requires that proper corrosion be maintained in the uppermost regions of the pipe in the well at all times and that the pipe be uniformly corroded.

[00182] Milling Module: The downhole tool may additionally contain an apparatus for cleaning crust or other materials deposited on the surface of the inner tubing to be dissolved. The milling apparatus may also be used to mill cement that may be behind the dissolved metal tubing. By including this apparatus in the downhole tool, the inner tubing can be cleaned and said inner tubing and cement can be removed at once, making the window opening operation more efficient. Figure 24 shows the rotary milling apparatus 43 at the bottom of the downhole tool. Said apparatus may contain expandable cutting blocks 44. These cutting blocks 44 are equipped with rigid milling components 46, such as PDC or tungsten cutters, among others, which can be operated to expand to remove cement behind the inner tubing.The milling apparatus 43 may also contain rigid milling components 46 placed in the bottom 45 of the milling apparatus to clean the inner tubing of crust or other material deposited on the surface of the inner tubing. The bottom 45 of the milling apparatus 43 may also be fitted with a conventional drilling bit.

[00183] Operation of the downhole tool: The brine contained in the well is conditioned to have the preferred conductivity.

[00184] The downhole tool is lowered into the well like a conventional cable drill tool. It is positioned at the desired depth and the clamps 5 and the connector for the internal metal tubing 4 are activated.

[00185] If the downhole tool is fitted with a milling device 43, said device may, at this stage, be used to Petition 870260033280, dated 10 / 04 / 2026, page 56 / 164 / 49 clean the internal piping of crust or other material deposits on its surface.

[00186] The conductive elements 1,10 are then supplied with the ideal electric current by a battery coupled to the power unit 7 or directly from the surface through the cable, at which point accelerated corrosion of the metal tubing 2 begins. The conductive elements 1,10 may also be supplied with vibration at an ideal frequency to allow the gas bubbles that form in the conductive element 1,10 to escape more quickly.

[00187] If only one conductive element 1 is used, it will be suspended in the center of the metal pipe when at least two clamps 4 / 5 are activated. Depending on the length of conductive element 1, the centralizer 37 may also be activated.

[00188] If multiple conductive elements 10 are present, expandable rails or other means may be used to position them, and the conductive elements 10 will be expanded to the desired distance from the metal tubing (although the distance is generally always limited by the non-conductive spacers 3). Once expanded to the ideal distance, the high electric current will be provided.

[00189] The temperature of the power unit 7 and the electrolyte is monitored, and heat from the power unit is transferred to the electrolyte to heat it, if desired. The direction and flow of the circulation module 6 (if present) can be adjusted both to cool the power unit 7, increase the temperature of the electrolyte surrounding the conductive elements 1,10, and to assist in the flow of hydrogen bubbles from the electrolytic process.

[00190] If the downhole tool is equipped with rotating conductive elements 10, then continuous or oscillating rotation will begin in order to level the corrosion in the metal pipe 2, to help to Petition 870260033280, dated 10 / 04 / 2026, page 57 / 164 / 49 clean the surface of the metal piping from corrosion products or assist the circulation of the electrolyte surrounding the conductive elements 1,10.

[00191] By using expandable conductive elements 10, the output of each power module 11 can be monitored. If any of the modules is providing a different current than the others, this may be an indication that the conditions around the conductive element 10 connected to said power module 11 are also different. The distance between each conductive element 10 and the metal tubing 2 can then be changed independently to modify the corrosion rate and overcome the consequences of the difference in electric current.

[00192] Geometric changes in the metal tubing 2, caused by corrosion, will result in changes in the electrolytic process conditions, affecting the voltage drop between the conductive elements 1,10 and the metal tubing 2, the electric current, and the power consumption. By monitoring these electrical measurements, the operator or software linked to the tool itself can determine whether the metal tubing has been partially or totally corroded. When using expandable conductive elements 10, measurements of how much the rails have expanded can provide information on the amount of metal tubing 2 that has been corroded.

[00193] If a caliper is used, this measurement can be made throughout the corrosion process.

[00194] Once the measurements correspond to the desired levels, the clamps 4,5 are released, if they contain expandable conductive elements 10, said conductive elements are closed and the tool can be moved to the desired position to continue the process.

[00195] The downhole tool preferably moves from a deeper to a shallower position in the well, resulting in preferable deep-to-shallow etching of the metal tubing 2. The downhole tool can be moved in several ways. How Petition 870260033280, dated 10 / 04 / 2026, page 58 / 164 / 49 examples, the tool can be moved by extracting the drilling cable or reel tubing connected to the downhole tool or by activating the connected downhole tractor or any other apparatus installed to move the tool in or along the wellbore.

[00196] Once the desired length of metal tubing 2 has been etched and the desired window size opened, the tool is extracted to the surface.

[00197] Depending on the well configuration, there may be cement behind the internal tubing that has dissolved. If the downhole tool is equipped with a milling device, this can be used to remove said cement.

[00198] In some wells, the metal tubing 2 will be surrounded by the formation. By corroding sections of the metal tubing 2, access to the formation will be obtained. Depending on the type of formation and the stability of the wellbore, said formation may trap the exposed conductive elements 1,10. Therefore, the downhole tool may, in some instances, contain a release mechanism that can be operated to separate the conductive elements 1,10 from the remainder of the downhole tool, so that parts of the tool can be extracted to the surface while the remaining components of the tool can become part of the cross-section barrier. Petition 870260033280, dated 10 / 04 / 2026, page 59 / 164

Claims

1 / 7 CLAIMS 1. A downhole tool for removing sections of metal pipe (2), the downhole tool comprising: one or more conductive elements (1, 10) arranged to corrode a section of metal pipe (2) using an electrolytic process, the one or more conductive elements (1, 10) being formed of electrically conductive material, an apparatus (4) for establishing a connection between the one or more conductive elements (1, 10) and the metal pipe (2), and a power unit (7) configured to provide an electric current to the one or more conductive elements (1, 10), characterized in that it further comprises one or more non-conductive spacers (3) configured to maintain a physical separation between the conductive elements (1, 10) and the metal pipe (2), and configured to seat against an inner surface of the metal pipe (2) during a corrosion process,and wherein at least a portion of the tool is configured to rotate and oscillate at least one of them so that the spacers (3) move against the pipe surface.

2. Well bottom tool according to claim 1, characterized in that the surface area size of the conductive element (1, 10) is between 0.8 and 4 times the internal surface area of ​​the metal pipe (2).

3. Downhole tool according to claim 1, characterized in that one or more conductive elements (1, 10) comprise non-conductive spacers (3).

4. Downhole tool according to claim 1, characterized in that the non-conductive spacers (3) provide a clearance of 0.05 mm to 30 mm between one or more conductive elements (1, 10) and the metal tubing (2). Petition 870260033280, dated 10 / 04 / 2026, p. 60 / 164 2 / 7 5. A downhole tool according to claim 1, characterized in that at least one portion of the tool is configured to rotate back and forth in an oscillating motion.

6. Downhole tool according to claim 1, characterized in that one or more conductive elements (1, 10) are made of electrically conductive material, such as steel, stainless steel, aluminum, copper, titanium, graphite, nickel or other alloy or coating that reduces the overvoltage between the conductive elements (1, 10) and an electrolyte.

7. Downhole tool according to claim 1, characterized in that at least one conductive element (1, 10) is centrally placed in the tool.

8. Downhole tool according to claim 1, characterized in that several conductive elements (1, 10) are coupled to the power unit (7) and mounted on expandable rails configured to move the conductive elements (1, 10) closer to the metal pipe (2).

9. Well bottom tool according to claim 8, characterized in that the conductive elements (1, 10) are configured to overlap each other or contain additional conductive elements (1, 10) that reduce the surface clearance caused by the expandable rails moving perpendicular to the longitudinal geometric axis of the metal pipe (2).

10. Downhole tool according to claim 8, characterized in that the conductive elements (1, 10) move closer to the metal tubing (2), independently of each other.

11. Downhole tool according to claim 8, characterized in that the conductive elements (1, 10) move closer to the metal tubing (2) to form a frustoconical composite conductive element and one side of the frustoconical composite conductive element with a smaller radius is closer to the apparatus (4) to establish a connection with the metal tubing (2).

12. Well bottom tool according to claim 1, characterized in that the surface of one or more conductive elements (1, 10) is molded with patterns of one of these notches or grooves.

13. Downhole tool according to claim 12, characterized in that the surface of one or more conductive elements (1, 10) comprises at least one of longitudinal grooves or helical grooves.

14. Well bottom tool according to claim 13, characterized in that the conductive elements (1, 10) are shaped to avoid sharp edges, and in that the grooves formed on the surface of the conductive elements (1, 10) have a sinusoidal cross-sectional profile.

15. Downhole tool according to claim 1, characterized in that the power unit (7) is configured to convert a low current / high voltage input from a power source into a high current / low voltage output for provision to the conductive elements (1, 10).

16. Downhole tool according to claim 15, characterized in that the output electric current is either DC or pulsating current and has high levels of electrical noise.

17. Downhole tool according to claim 15, characterized in that the inlet and outlet of the power unit (7) are electrically isolated from each other.

18. Downhole tool according to claim 15, characterized in that the input to the power unit (7) is between 400 and 3,000 volts and the output current from the power unit (7) is between 0 and 15,000 Amps.

19. Downhole tool according to claim 15, characterized in that the power unit (7) comprises one or more power modules (11) that are connected to one or more conductive elements (1, 10) through the same common conductors.

20. Downhole tool according to claim 15, characterized in that the power unit (7) comprises more than one power module (11) and the tool comprises more than one conductive element (1, 10), and each of the power modules (11) is independently connected to a different of the conductive elements (1, 10).

21. Downhole tool according to claim 15, characterized in that the power unit (7) comprises one or more power modules (11) and the conductors connecting the power modules (11) to the conductive elements (1, 10) are placed within the main chassis of the downhole tool.

22. Downhole tool according to claim 1, characterized in that the conductive element (1, 10), or a composite element comprising more than one conductive element (1, 10), has a smaller diameter at an upper end and a larger diameter at a lower end.

23. Downhole tool according to claim 22, characterized in that the conductive element (1, 10), or a composite element comprising more than one conductive element (1, 10), has a truncated conical shape.

24. Downhole tool according to claim 1, characterized in that one or more conductor elements (1, 10) are configured to rotate continuously.

25. Downhole tool according to claim 1, characterized in that the downhole tool is submerged in an electrolyte having a salt concentration between 2 and 30% by weight.

26. Downhole tool according to claim 1, characterized in that the tool is configured to be moved during the corrosion process from a deeper position to a shallower position in the well.

27. Downhole tool according to claim 1, characterized in that it comprises components for actuating fluid circulation around the conducting elements (1, 10) and the power unit (7).

28. Downhole tool according to claim 27, characterized in that the components are integral with the conductive elements (1, 10).

29. A downhole tool according to claim 27, characterized in that the components for actuating fluid circulation are made of non-conductive abrasive material and are used as abrasive or milling elements, the elements being shaped to actuate fluid circulation.

30. Downhole tool according to claim 1, characterized in that it contains at least one clamping module comprising a mechanical, hydraulic or electromagnetic device for anchoring and centering the downhole tool and the conductive elements (1, 10) in the metal pipe (2).

31. Downhole tool according to claim 1, characterized in that the tool further comprises a profiling sensor for recording the properties from Petition 870260033280, dated 10 / 04 / 2026, page 64 / 164 6 / 7 of the formation, cement, metal piping (2) and environment around the tool.

32. Downhole tool according to claim 1, characterized in that it comprises a mechanism configured to separate the conductive elements (1, 10) of the downhole tool in response to user input.

33. Well bottom tool according to claim 1, characterized in that it comprises an apparatus configured to measure the progress of the corrosion process located on or adjacent to the bottom edge of the conductive elements (1, 10), providing measurements of a thickness of the metal pipe (2) at a height that is located between a height of 100 mm above the bottom end of the conductive element (1, 10) to a height of 100 mm below the bottom end of the conductive element (1, 10).

34. Downhole tool according to claim 1, characterized in that the downhole tool is provided with power by means of one of a wire coupled to a surface power source or a downhole battery or a downhole power generator.

35. Downhole tool according to claim 1, characterized in that one or more non-conductive spacers (3) are placed at an angle relative to a longitudinal geometric axis of the tool.

36. Downhole tool for removing metal pipe sections (2), the downhole tool comprising: one or more conductive elements (1, 10) arranged to corrode a metal pipe section (2) using an electrolytic process, the one or more conductive elements (1, 10) being formed of electrically conductive material, Petition 870260033280, dated 10 / 04 / 2026, page.65 / 164 7 / 7 an apparatus (4) for establishing a connection between one or more conductive elements (1, 10) and the metal pipe (2), a power unit (7) configured to provide an electric current to one or more conductive elements (1, 10), characterized in that the power unit (7) is configured to convert a low current / high voltage input from a power source into a high current / low voltage output for provision to the conductive elements (1, 10), and the tool comprises a device configured to obtain measurements of the output current from the power unit (7) and the measurements are used to monitor the corrosion of the metal pipe (2).

37. Downhole tool for removing sections of metal piping (2), the downhole tool comprising: one or more conductive elements (1, 10) arranged to corrode a section of metal piping (2) using an electrolytic process, the one or more conductive elements (1, 10) being formed of electrically conductive material, an apparatus (4) for establishing a connection between the one or more conductive elements (1, 10) and the metal piping (2), a power unit (7) configured to provide an electric current to the one or more conductive elements (1, 10), characterized in that the tool further comprises at least one device for providing vibration to the conductive element (1, 10). Petition 870260033280, dated 10 / 04 / 2026, p. 66 / 164

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