Diamond coating on cones for expandable tubes

Abstract

An expansion cone 2 for expanding an expandable tube 3, the expansion cone comprising: a base material 20 selected from the group consisting of an alloy steel, a tungsten carbide coated alloy steel and sintered tungsten carbide; an intermediate buffer layer 26; and a coating layer 25 deposited on an outer surface of the intermediate buffer layer; wherein an intermediate buffer layer is deposited between the outer surface of the steel alloy base material and the coating, wherein the intermediate buffer layer is one or more selected from the group consisting of silicon (Si), titanium (Ti) and silicon carbide (SiC); wherein the coating is a diamond-containing coating.

Description

Background Art

[0001] The expansion tube technology is generally used to repair damaged casing, plug water leakage areas, plug lost circulation areas, increase the inner diameter of the casing to speed up production, save casing in single-hole casing design, and improve sand control efficiency due to the reduction of the annular space between the expansion filter and the borehole.

[0002] In order to reduce the loss of inside diameter each time a new casing string or liner is installed, a cold working process was developed whereby the casing or liner can be expanded in diameter by up to 20% after running downhole. To do this, an expansion cone that exceeds the required expansion of the inside diameter of the pipe is forced through the pipe. This can be done hydraulically by applying mud pressure or mechanically by pulling on the expansion cone. The expansion needs to be reliable, especially when expanding thousands of feet below the surface.

[0003] As shown in Figure 1, the main components of the expandable pipe system include the pipe to be expanded 3 and the expansion cone 2 used to push the pipe, as described above. During the expansion process, the outer diameter of the cone 2 exerts a force on the inner diameter of the pipe 3. The pipe 3 then expands outward and undergoes permanent plastic deformation within a range determined by the geometry and material properties of the pipe and cone. As the expansion cone 2 moves through the pipe 3, the unexpanded section 3a is processed by the cone, expanding the pipe into a pipe section 3b with a larger inner diameter.

[0004] During the interaction between the expansion cone and the expandable tube, the friction between the expansion cone and the expandable tube can be high, especially along the transition section 3c, where most of the force is applied to the tube. The friction is determined by several factors, including material, cone angle, surface roughness, lubrication, load level, etc. In some cases, the friction is high enough to cause adverse friction damage to the cone and the tube. In some other cases, wear occurs between the expansion cone and the expandable tube, especially in applications used to expand stainless steel tubes, aluminum tubes, or nickel-based alloy tubes. Wear can also cause damage to the cone and tube as a kind of cold weld between the two components.

[0005] Therefore, a coating between the expansion cone and the expandable tube is necessary to reduce the friction and wear tendency between the cone and the tube. Without a coating, the alloy steel of the cone may have a relatively high coefficient of dynamic friction relative to the carbon steel or stainless steel of the tube. When stainless steel, aluminum alloy or nickel-based alloy rubs vigorously against other steel parts, the surface oxide layer will be destroyed and the new steel matrix will be exposed, which can react with other steel parts under high compressive forces to produce cold welds.

[0006] In order to possibly reduce the friction and wear tendency between the cone and the tube and increase the life of the expansion cone, the conventional expandable tube technology applies a tungsten carbide (WC) layer as a hard coating on the steel substrate of the expansion cone. In this case, under the Vickers hardness test, the hardness of the WC layer can range from Vickers pyramid number (HV) 850 to HV 1350, depending on the material, grain structure and application process.

[0007] However, in some cases, large WC particles in the hard coating can damage the inner surface of the expandable tube. In other cases, the WC layer is formed by thermally spraying a WC-based coating on a steel cone, where the grain size of the WC is only about a few microns and the coating surface is polished to minimize erosion. The damage to the expandable tube by the WC grains on the cone is minimized, but the coating can still have a relatively high coefficient of friction. Therefore, in expandable tube applications, a WC hard coating alone on the steel substrate of the expansion cone is not a favorable protection.

[0008] Another method of reducing the friction caused by the contact between the expansion cone and the expandable tube is to increase the lubricity of the drilling mud. In industrial drilling operations, attempts have been made to reduce friction mainly by using water-based and / or oil-based lubricants containing various types of expensive and often environmentally unfriendly additives. Diesel and / or mineral oils are also often used as lubricants, but the handling of lubricants is problematic. Certain minerals, such as bentonite, which are known to help reduce friction between drill pipe components and materials such as Teflon, have also been used to reduce friction. However, these materials also lack durability and strength. Other additives used include vegetable oils, asphalt, graphite, detergents, and walnut shells, but each additive has its own limitations. Summary of the invention

[0009] In general, in one aspect, embodiments of the present invention relate to an expansion cone for expanding an expandable tube. The expansion cone includes: a base material selected from the group consisting of alloy steel, alloy steel coated with tungsten carbide, and sintered tungsten carbide; an intermediate buffer layer; and a coating deposited on the outer surface of the intermediate buffer layer. The intermediate buffer layer is deposited between the outer surface of the steel alloy base material and the coating, wherein the intermediate buffer layer is one or more selected from the group consisting of silicon (Si), titanium (Ti), and silicon carbide (SiC). The coating is a diamond-containing coating.

[0010] In general, in another aspect, embodiments herein relate to an expansion cone for expanding an expandable tubular. The expansion cone comprises: a base material having an upper cylindrical section, a lower cylindrical section, and a conical section therebetween; a plurality of recesses formed at least within the conical section of the steel alloy base material; a plurality of inserts disposed within the plurality of recesses. The plurality of inserts comprises an outer surface layer or coating selected from the group consisting of nanocrystalline diamond, amorphous diamond, diamond-like carbon, and mixtures thereof.

[0011] In general, in yet another aspect, embodiments herein relate to a method for forming an expansion cone for expanding an expandable tube. The method includes: forming a base expansion cone having an upper cylindrical section, a lower cylindrical section, and a conical section therebetween; forming a plurality of recesses in the conical section of the base expansion cone; and disposing a plurality of inserts in the plurality of recesses. The plurality of inserts are selected from the group consisting of unleached diamond-cobalt compacts, leached diamond-cobalt compacts, diamond-silicon compacts, binderless diamond compacts, diamond-boron nitride composite compacts, and combinations thereof.

[0012] Other aspects and advantages will be apparent from the following description and the appended claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] FIG. 1 is a schematic diagram of an expansion cone in an expandable tubular system without a coating used in the prior art.

[0014] 2a-2b are schematic diagrams of expansion cones according to embodiments herein.

[0015] 3a-3f are schematic diagrams of expansion cones according to embodiments herein, and FIG. 3b is a cross-sectional view.

[0016] 4a-4e are schematic diagrams of expansion cones in an expandable tubular system according to embodiments disclosed herein.

[0017] Figure 5 is a schematic diagram of an expansion cone according to an embodiment disclosed herein. DETAILED DESCRIPTION

[0018] In view of the required expansion properties of expandable tubes, and the deficiencies of the above-mentioned prior art methods of reducing friction, a low friction coating with improved properties is needed. Considering the operating environment of these applications, which typically includes high loads and severe abrasive conditions, traditional and conventional low friction coatings (e.g., graphite, MoS2, WS2) may not meet the durability requirements in some cases. Therefore, one or more embodiments of the present disclosure are directed to an expansion cone, which includes a coating or insert for reducing friction between an expansion cone and an expandable tube.

[0019] In one aspect, embodiments of the present disclosure relate to an expansion cone that includes a diamond-containing coating to reduce friction between the expansion cone and the expandable tube. The diamond-containing coating, for example, can be a diamond coating or a diamond-like coating (DLC). By including a diamond-containing coating on the expansion cone, advantages such as increased hardness of the cone, reduced coefficient of friction, increased wear resistance, and extended life of the cone can be achieved.

[0020] Referring now to FIG. 2 a, a schematic diagram of an expansion cone according to an embodiment of the present invention is illustrated. Since the present disclosure relates to the outer surface of the expansion cone, the connections and one or more internal flow paths within the expansion cone are not illustrated. The expansion cone 20 may include a base material 23 having an upper cylindrical section 23 a, a lower cylindrical section 23 b, and a conical section 23 c therebetween. In some embodiments, the base material may be a steel alloy. In a particular embodiment, the steel alloy may be selected from the group consisting of alloy steel, alloy steel coated with tungsten carbide, and sintered tungsten carbide.

[0021] Diamond or diamond-like coating 25 can be arranged on at least a portion of the outer surface of the base material. In some aspects, the diamond coating can be made of nanocrystalline diamond, amorphous diamond or a mixture thereof. The diamond coating can be obtained by chemical vapor deposition (CVD), and chemical vapor deposition (CVD) includes filament-assisted thermal CVD, electron-assisted thermal CVD, laser-assisted thermal CVD, radio frequency plasma CVD, microwave plasma CVD, combustion flame-assisted CVD, DC arc plasma jet CVD and other processes known in the art. In other aspects, the coating can be made of diamond-like carbon (DLC). DLC can be obtained by ion beam deposition, sputtering deposition, plasma-assisted chemical vapor deposition, electron-excited plasma CVD (EEP-CVD), pulse cathode arc deposition and magnetron sputtering ion plating process, etc.

[0022] While the coating is illustrated in Figure 2a as being deposited over the entire outer surface area of ​​the base material cone, embodiments herein contemplate coating only the cone segment 23c, since this is the portion of the cone that encounters the greatest amount of friction. Embodiments herein also contemplate coating the cone segment and portions of the upper cylindrical segment 23a and lower cylindrical segment 23b adjacent to the cone segment 23c, providing low friction areas for entering and exiting high friction zones.

[0023] In one or more embodiments, the expansion cone may further include a buffer layer between the base material and the coating to achieve better crystal bonding between the diamond or diamond-like coating and the base material matrix of the cone. Referring now to FIG. 2 b, the expansion cone may include a base material 23 having an upper cylindrical section 23 a, a lower cylindrical section 23 b, and a conical section 23 c therebetween. In some embodiments, the base material may be a steel alloy or sintered tungsten carbide. In a particular embodiment, the steel alloy may be selected from the group consisting of a free alloy steel and an alloy steel coated with tungsten carbide.

[0024] The intermediate buffer layer 26 may be disposed on at least a portion of the outer surface of the base material. As used herein, "intermediate buffer layer" and "buffer layer" are used interchangeably. The thickness of the buffer layer 26 may be, for example, as thin as 1 to 5 μm, but may also be as thick as 100 to 300 μm. The buffer layer may be formed of one or more selected from the group consisting of silicon (Si), titanium (Ti), and silicon carbide (SiC).

[0025] After depositing the buffer layer 26 on the base material 23 or a portion thereof, a diamond coating can be deposited on top of the buffer layer 26. The diamond or diamond-like coating 25 can be disposed on at least a portion of the outer surface of the buffer layer 26. In some aspects, the diamond coating can be made of nanocrystalline diamond, amorphous diamond, or a mixture thereof. In other aspects, the coating can be made of diamond-like carbon (DLC). As with the embodiment of FIG. 2a, the buffer layer and the diamond or diamond-like coating can be applied to all or a portion of the outer surface of the cone.

[0026] In another aspect, embodiments of the present disclosure relate to an expansion cone that includes an insert to reduce friction between the expansion cone and the expandable tube. The insert may be a diamond block or an insert including a diamond or diamond-like coating. By including such an insert on the expansion cone, advantages such as improved wear resistance, reduced coefficient of friction, and extended life of the cone may be achieved.

[0027] Referring now to FIGS. 3a-3f, schematic diagrams of expansion cones and inserts including inserts are shown. Similar to the above-described embodiments, the expansion cone 50 may include a base material having an upper cylindrical section 23a, a lower cylindrical section 23b, and a conical section 23c therebetween (see FIGS. 2a-2b). The expansion cone may also include a plurality of inserts 55 disposed within recesses 57 formed in the base material of the cone (FIG. 3b).

[0028] As shown in the embodiments of Figures 3a, 3c and 3d, the pockets 57 and inserts 55 can be disposed along the length of the tapered segment. Embodiments herein additionally contemplate the placement of inserts along the upper cylindrical segment, the lower cylindrical segment, a combination thereof, or portions thereof. For example, embodiments herein also contemplate the use of inserts in the tapered segment and portions of the upper and lower cylindrical segments adjacent to the tapered segment to provide low friction areas entering and exiting high friction zones.

[0029] The inserts, also referred to herein as diamond blocks, are illustrated in Figures 3a-3f as rectangles. Other shapes may be used for the inserts, including, for example, cylindrical, square, triangular, trapezoidal, and other shapes or combinations thereof, as those skilled in the art can easily envision. In addition, the inserts may be arranged on the expansion cone in a variety of ways, such as horizontally parallel (Figure 3a), vertically parallel (Figure 3b), or at an angle (Figure 3c). Other patterns, such as spiral or spiral patterns, etc., may be easily envisioned. In some embodiments, the inserts may be arranged so that there is an overlap between the rows in the vertical direction, thereby providing at least some friction reduction along all vertical paths of the conical section of the cone between the cone and the expandable tube being processed. In other embodiments, inserts of different shapes may be deposited on different sections of the cone, as those skilled in the art can easily envision. For example, a triangle may be deposited on an upper cylindrical section, while a rectangle may be deposited on a conical section. Other combinations may also be considered.

[0030] The insert and its corresponding recess may be sized, spaced and used in such a manner that the physical integrity of the base expansion cone is not compromised. The specific size and spacing may depend, for example, on the size and configuration of the expansion cone and other variables. The recess and insert may be further sized and configured such that the insert may be pressed into and retained within the recess. Optionally, the insert may be brazed into the recess.

[0031] Figures 3e and 3f illustrate embodiments of inserts or diamond blocks. The diamond blocks may include unleached diamond-cobalt compacts, leached diamond-cobalt compacts, diamond-silicon compacts, binderless diamond compacts, diamond-boron nitride composite compacts, and combinations thereof. Typical geometries may vary, such as a 10×5×5 mm rectangle, an OD 10×5 mm disk, etc. The diamond block may include a base block formed of a material that may be a steel alloy or sintered tungsten carbide in some embodiments. In a particular embodiment, the steel alloy may be selected from the group consisting of alloy steel and alloy steel coated with tungsten carbide.

[0032] Diamond or diamond-like coating can be arranged on at least a portion of the outer surface of the base material of the insert. In some aspects, the diamond coating can be made of nanocrystalline diamond, amorphous diamond or a mixture thereof. The diamond coating can, for example, be obtained by chemical vapor deposition (CVD), and chemical vapor deposition (CVD) includes filament-assisted thermal CVD, electron-assisted thermal CVD, laser-assisted thermal CVD, radio frequency plasma CVD, microwave plasma CVD, combustion flame-assisted CVD, DC arc plasma jet CVD and other processes known in the art. In other aspects, the coating can be made of diamond-like carbon (DLC). DLC can be obtained by ion beam deposition, sputtering deposition, plasma-assisted chemical vapor deposition, electron-excited plasma CVD (EEP-CVD), pulsed cathode arc deposition and magnetron sputtering ion plating process, etc.

[0033] In some embodiments, the buffer layer may be disposed on at least a portion of the outer surface of the base material. The thickness of the intermediate buffer layer, for example, may be as thin as 1 to 5 μm, but may also be as thick as 100 to 300 μm. The buffer layer may be formed of one or more selected from the group consisting of silicon (Si), titanium (Ti), and silicon carbide (SiC).

[0034] As described above, the diamond coating and the intermediate buffer layer may be disposed on at least a portion of the outer surface of the block. For example, the diamond coating may be applied only to the face of the block that will be exposed after insertion into the recess. In some embodiments, the diamond coating may be applied only to a portion of the face of the block that will be exposed after insertion into the recess. For example, the coating may be formed on one or more discrete areas and may be patterned along the surface, such as to form a pad or band of diamond coating on the surface of the insert. In one embodiment, the thickness of the diamond coating may be in the range of 1 to 50 microns. In another embodiment, the thickness of the diamond coating may be in the range of 5 to 25 microns. In yet another embodiment, the thickness of the diamond coating may be in the range of 10 to 20 microns.

[0035] In another aspect, embodiments of the present disclosure are directed to an expansion cone including a diamond insert. The insert may be 1 to 50 microns above the surface of the cone base material. In another embodiment, the insert may be 5 to 25 microns above the surface of the cone base material. In yet another embodiment, the insert may be 10 to 20 microns above the surface of the cone base material.

[0036] As described above, embodiments disclosed herein relate to an expansion cone that can be used to expand an expandable tube and can be used to reduce friction between the expansion cone and the expandable tube being processed. As described, embodiments of the expansion cone may include an alloy steel base material selected from alloy steel and alloy steel coated with tungsten carbide. Optionally, embodiments of the expansion cone may include sintered tungsten carbide. The expansion cone may also include a coating deposited on the outer surface of the expansion cone or an insert that provides a surface area with a coating exposed near the outer surface of the expansion cone. The expansion cone or insert may also include a buffer layer between the base material of the cone or insert and the coating.

[0037] Diamond or diamond-like coatings may have the beneficial properties of high hardness, low coefficient of friction and low wear tendency with steel. High hardness may provide high wear resistance to extend the life of the cone. Their coefficient of friction with other mating metal materials of the tube is typically much lower than that of the original material without the coating.

[0038] In one or more embodiments, the coating may be a diamond coating selected from the group consisting of nanocrystalline diamond, amorphous diamond, and mixtures thereof. The diamond coating has the beneficial properties of high hardness and wear resistance to extend the life of the cone. The friction coefficient of the diamond coating herein with other mating materials is generally lower than the friction coefficient of the raw material without the coating. In addition, with the coating on the cone, the wear tendency between the cone and the tube will be significantly reduced.

[0039] In other embodiments, the coating may be diamond-like carbon (DLC). DLC coatings have similar benefits as diamond coatings.

[0040] Thus, by applying a coating and a buffer layer to the substrate of an expansion cone or insert, the friction and chance of wear can be significantly reduced. While the coating can provide reduced friction, in some embodiments, the diamond or diamond-like coating can be configured to flake or partially flake during use, such as when the outer surface of the expansion cone engages the expandable tubing. In some embodiments, the flakes of the coating can act as a solid lubricant, providing further lubrication between the tubing and the expansion cone.

[0041] Turning now to Figures 4a-4e, schematic diagrams of embodiments of expansion cones disposed in and processed on an expandable tubular system are shown. Starting with Figure 4a, an expandable tubular 40 processed by an expansion cone 20 includes an unexpanded tubular section 43a, an expanded tubular section 43b, and a joint or transition zone 43c undergoing expansion.

[0042] The expansion cone 20 may be made of, for example, alloy steel, tungsten carbide coated alloy steel or sintered tungsten carbide material as described for Figures 2a-2b and 3a-3d. The expandable tube 40 may be made of, for example, expandable steel, braided steel, nickel-based alloys, aluminum alloys and non-metallic composite materials.

[0043] As described above, the expansion cone 20 can be pushed or pulled through the expandable tube using hydraulic or mechanical means. As shown in FIG1 , during the time when the fluid applies pressure to the expansion cone 20, causing the expansion cone to move through the expandable tube, the expansion cone 20 exerts a force on the joint segment 43c and plastically deforms the tube, thereby causing the unexpanded tube segment 43a to expand to form the expanded tube segment 43b. The pressure generates friction between the expansion cone 20 and the expandable tube 40. When there is no diamond coating between the expansion cone 20 and the expandable tube 40, the friction force is directly applied to the area of ​​the joint 43c. Due to the material properties of the expansion cone 20 and the expandable tube 40, there is a high coefficient of friction between the surface of the expansion cone 20 and the surface of the expandable tube 40, resulting in a high tendency to wear. However, as shown in FIG4a , the expansion cone 20 has a diamond coating or diamond-like coating 25 deposited on the outer surface of the expansion cone 20. The high hardness property of the diamond coating 25 provides high wear resistance to extend the life of the expansion cone 20 and reduce the wear of the expansion cone 20 and the tube 40 during expansion. Furthermore, since the friction coefficient between the diamond coating 25 and other mating metal materials of the tube is much lower than the friction coefficient of the raw material without the coating, the wear tendency between the expansion cone 20 and the tube is significantly reduced.

[0044] Another advantage of applying the diamond or diamond-like coating 25 is that the diamond or diamond-like coating 25 can also act as a dry lubricant. The dry lubricant, although in a solid phase, can reduce the friction between the surface of the expansion cone 20 and the surface of the expandable tube 40 without the need for a liquid oil medium or other lubricant. In addition, even if there may be any flakes of the diamond coating 25, the flakes will not act as a harmful foreign body, but can act as an additional dry lubricant to facilitate the expansion process.

[0045] Reference is now made to Figures 4b-4e, which illustrate similar expansion processes using expansion cones according to other embodiments herein. Figure 4(b) illustrates the use of an embodiment of the expansion cone 20 of Figure 2(b) including an intermediate buffer layer 26 between the base cone material and the diamond or diamond-like coating 25. Figures 4c-4e illustrate the use of an embodiment of the expansion cone of Figures 3a, 3c and 3d including diamond blocks 55 to provide lubricity and wear resistance along the transition zone 43c during expansion of the tube 40, as well as other beneficial properties.

[0046] Embodiments herein also relate to methods for forming an expansion cone that can be used to expand an expandable tube. In one or more embodiments, a method for forming an expansion cone (e.g., the expansion cone 20 of FIG. 2b) includes forming a base expansion cone, such as a material selected from the group consisting of alloy steel, alloy steel coated with tungsten carbide, and sintered tungsten carbide. For example, the base expansion cone can be a solid expansion cone or a retractable expansion cone. After forming the base expansion cone, the method may include depositing a buffer layer 26 on at least a portion of the base expansion cone, and then depositing a diamond or diamond-like coating 25 on the buffer layer previously deposited on the base expansion cone.

[0047] In one or more embodiments, the diamond coating 25 can be applied by chemical vapor deposition (CVD). CVD is a vacuum deposition method for producing thin films. In some embodiments, the thickness of the diamond coating 25 can be in the range of 1 μm to 300 μm, for example, the coating thickness is in the range of 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 10 μm, 25 μm or 50 μm to an upper limit of 5 μm, 10 μm, 25 μm, 50 μm, 100 μm, 150 μm, 200 μm or 300 μm, wherein any lower limit can be combined with any upper limit. The diamond coating can be made of nanocrystalline diamond, amorphous diamond or a mixture thereof, and has the beneficial properties of high hardness, low friction coefficient and low wear tendency with steel. The cone is typically placed in a vacuum chamber. A carbon-containing gas precursor is injected into the chamber and dissociated by a thermal, plasma or combustion process to promote diamond nucleation and growth. Typical substrate temperatures may be between 500 and 1200°C.

[0048] In the method of placing the diamond-like coating on the outer surface of the expansion cone 20, the method of applying the diamond-like coating may include ion beam deposition (IBD), sputtering deposition, plasma-assisted chemical vapor deposition (CVD), electron-excited plasma CVD (EEP-CVD), pulsed cathode arc deposition and magnetron sputtering ion plating processes, etc. The DLC coating is processed in a vacuum or atmospheric environment by decomposing hydrocarbon gas under a trigger source such as plasma, arc, ion beam and pressure. 2 Bonds can be made at low temperatures as low as 200°C on substrates with SP 3Bond mixing to form a DLC coating. The diamond-like coating can be made of diamond-like carbon, such as tetrahedral amorphous carbon. The properties of the diamond-like coating may depend on the deposition method and parameters used. The high hardness nature of the diamond-like coating provides high wear resistance to extend the life of the expansion cone. The friction coefficient of the diamond-like coating and other matching metal materials of the tube is typically much lower than the friction coefficient of the raw material without the coating. In addition, in the case of a coating on the expansion cone, the wear tendency between the expansion cone and the expandable tube can be significantly reduced. As described above, another advantage of applying a diamond-like coating is that the diamond-like coating can also act as a dry lubricant, thereby reducing the friction between the surface of the expansion cone and the surface of the expandable tube. The diamond-like coating as used herein also prevents wear due to its tribological properties. In particular, the diamond-like coating used herein exhibits enhanced wear resistance and abrasion resistance, making them suitable for applications subjected to extreme contact pressures and severe abrasive environments. In one or more embodiments, the thickness of the diamond-like coating may be in the range of 1 μm to 300 μm, for example, the coating thickness is in the range of a lower limit of 1 μm, 2 μm, 3 μm, 4 μm, 5 μm or 10 μm to an upper limit of 5 μm, 10 μm, 25 μm, 50 μm or 100 μm, where any lower limit may be combined with any upper limit.

[0049] A buffer layer may be placed between the expansion cone substrate and the diamond or diamond-like coating to obtain better bonding and / or high hardness zones. The buffer layer in the embodiments herein may be made of silicon (Si), titanium (Ti) and silicon carbide (SiC) or a mixture thereof. The thin buffer layer may be applied by physical vapor deposition (PVD) or CVD. Both PVD and CVD are vacuum deposition methods for producing thin films. PVD may be a line of sight coating process that allows thin coatings and sharp edges, while CVD may generally be thicker and better protected from heat. Either method may be applied when depositing the buffer layer 6 to achieve better crystal bonding with both the steel substrate and the subsequent diamond coating 5. The PVD process evaporates material from a condensed phase into a gas phase. It then condenses back into a condensed phase on the substrate of the target portion to form a coating.

[0050] In one or more embodiments, the thickness of the intermediate buffer layer can be in the range of 1μm to 300μm, for example, the coating thickness is in the range of a lower limit of 1μm, 2μm, 3μm, 4μm, 5μm, 10μm, 25μm or 50μm to an upper limit of 5μm, 10μm, 25μm, 50μm, 100μm, 150μm, 200μm or 300μm, where any lower limit can be combined with any upper limit.

[0051] In yet another embodiment, the buffer layer may be a WC-based coating. For example, the WC-based coating may be applied to the steel substrate of the expansion cone by thermal spraying. The hardness of the WC-based thermal spray coating is typically as high as HV 850 to 1350 to improve the wear resistance of the expansion cone. The coefficient of friction with the casing may still be as high as 0.45 under dry conditions and as high as 0.12 in water-based drilling mud. In one or more embodiments disclosed herein, an additional thin diamond or diamond-like coating may be deposited on top of the WC-based coating, allowing a significant reduction in the coefficient of friction against the pipe without sacrificing the strength and toughness of the cone substrate. In such an embodiment, the coefficient of friction may be as low as 0.05.

[0052] In one or more embodiments, the buffer layer may include multiple coatings. For example, the buffer layer may include an additional adhesion layer that can be used to enhance the overall toughness of the coating and improve the compatibility between the base layer and the Si, Ti or SiC buffer layer or between the Si, Ti or SiC buffer layer and the diamond or diamond-like coating.

[0053] As described above, the intermediate buffer layer(s) and the diamond or diamond-like coating may be applied to all or a portion of the outer surface of the expansion cone. For example, the buffer layer and the diamond or diamond-like coating may be disposed only on the outer surface region of the transition zone of the expansion cone. In some embodiments, the buffer layer and the diamond or diamond-like coating may be disposed only on the outer surface region of the transition zone of the expansion cone and one or both of the upper and lower cylindrical segments or a portion of one or both of the upper and lower cylindrical segments. For example, Figure 5 As shown, the intermediate buffer layer 26 and the diamond or diamond-like coating 25 may extend into a portion of the upper cylindrical segment 23a and the lower cylindrical segment 23b, and in some embodiments, the buffer layer 26 may extend further into the cylindrical segment than the coating 25. In embodiments where the layer extends to the upper cylindrical segment and / or the lower cylindrical segment, the buffer layer 26 and / or the diamond coating 25 may cover as little as 1% to as much as 100% of the outer surface area of ​​the (one or more) cylindrical segments, such as from 1%, 5%, 10% or 25% to 15%, 25%, 50%, 75% or 100% of the surface area, where any lower limit may be combined with any upper limit.

[0054] Table 1 is a comparison of the friction coefficient and wear tendency of different materials (alloy steel, tungsten carbide, diamond coating and DLC) measured under dry conditions. As shown in Table 1, the friction coefficient of the expansion cone with diamond coating and DLC is significantly lower than that of the alloy steel expansion cone or the expansion cone with an external tungsten carbide layer. In addition, the wear tendency of the expansion cone with diamond coating and DLC is also very low.

[0055] Table 1 Friction coefficient and wear tendency of various materials (under dry conditions)

[0056]

[0057] Other embodiments herein relate to a method for forming an expansion cone that can be used to expand an expandable tube, wherein the expansion cone includes a diamond block, as shown in Figures 3a-3f. The method may include forming a basic expansion cone having an upper cylindrical section, a lower cylindrical section, and a conical section therebetween. A recess may be formed in the basic expansion cone. In some embodiments, the recess may be formed only in the conical section. In other embodiments, the recess may be formed in the conical section and one or both of the upper and lower cylindrical sections or portions thereof. When formed only in a portion of the cylindrical section, the recess may be formed in an area adjacent to the conical section and may include portions or areas similar to those described above with respect to the coating and buffer layer.

[0058] After forming a base expansion cone with pockets formed therein, the method may include placing an insert in each pocket. The insert may include a diamond block, or may be an insert having an outer surface layer or coating selected from the group consisting of nanocrystalline diamond, amorphous diamond, diamond-like carbon, or mixtures thereof.

[0059] The method for forming an expansion cone with an insert may also include a step for forming the insert. For example, forming the insert may include a step of forming a base insert such as a material selected from the group consisting of alloy steel, alloy steel coated with tungsten carbide, and sintered tungsten carbide. Forming the insert may also include depositing a buffer layer on at least a portion of the base insert and depositing an outer surface layer or coating on the buffer layer. The buffer layer and the coating may be formed using the process described above and may have similar thicknesses and properties.

[0060] The high hardness properties of the plurality of diamond blocks 55 provide high wear resistance to extend the life of the expansion cone or reduce wear on the tube. Their coefficient of friction with other mating metal materials of the tube is typically much lower than that of the raw material without the coating, and may be as low as described in Table 1 above. In addition, with the coating on the diamond blocks, the wear tendency between the expansion cone and the tube can be significantly reduced.

[0061] Another advantage of applying the plurality of diamond chunks is that the plurality of diamond chunks can also act as a dry lubricant. Although in a solid phase, the coating on the plurality of diamond chunks can act as a dry lubricant and can reduce the friction between the surface of the expansion cone and the surface of the expandable tube without the need for a liquid oil medium. Furthermore, even if any flakes of the plurality of diamond chunks are present, the flakes do not act as harmful foreign matter, but can act as a dry lubricant to facilitate the expansion process.

[0062] As shown in Figures 3a-3f, the pockets may be arranged in any number of configurations along the expansion cone. Multiple diamond blocks may be set in the pockets by pressing. Optionally, the blocks may be brazed into the pockets. The diamond blocks may include unleached diamond-cobalt compacts, leached diamond-cobalt compacts, diamond-silicon compacts, binderless diamond compacts, diamond-boron nitride composite compacts, and combinations thereof. Typical geometries may vary, such as a 10×5×5 mm rectangle, an OD 10×5 mm disk, etc.

[0063] Although the present disclosure has been described in conjunction with its specific exemplary embodiments, it is apparent that, based on the above description, many changes, modifications and variations will be apparent to those skilled in the art without departing from the spirit or scope of the present disclosure. Therefore, the present disclosure is intended to cover all such changes, modifications and variations described in detail above.

[0064] When numerical lower limits and numerical upper limits are listed herein, ranges from any lower limit to any upper limit, including intermediate points therebetween, are contemplated.

Claims

1. An expansion cone for expanding an expandable tube, the expansion cone comprising: a base material selected from the group consisting of alloy steel, alloy steel coated with tungsten carbide, and cemented tungsten carbide; Intermediate buffer layer; and a coating deposited on an outer surface of the intermediate buffer layer; wherein the intermediate buffer layer is deposited between the outer surface of the steel alloy base material and the coating layer, wherein the intermediate buffer layer is one or more selected from the group consisting of silicon (Si), titanium (Ti) and silicon carbide (SiC); The coating is a diamond-containing coating.

2. The expansion cone according to claim 1, wherein the coating is a diamond coating selected from the group consisting of nanocrystalline diamond, amorphous diamond and mixtures thereof.

3. The expansion cone according to claim 1, wherein the coating is a diamond-like coating (DLC) made of diamond-like carbon.

4. The expansion cone according to any one of claims 1 to 3, further comprising an upper cylindrical section, a lower cylindrical section and a conical section between the upper cylindrical section and the lower cylindrical section, wherein the intermediate buffer layer and the coating are deposited on at least the outer surface of the conical section.

5. An expansion cone according to any one of claims 1 to 4, wherein the coating has a coefficient of friction measured against steel of between 0.02 and 0.

25.

6. An expansion cone according to any one of claims 1 to 5, wherein the coating is configured to flake during use, and the flakes of the coating are configured to act as a dry lubricant.

7. An expansion cone for expanding an expandable tube, the expansion cone comprising: A base material having an upper cylindrical section, a lower cylindrical section, and a tapered section therebetween; a plurality of pockets formed in at least said tapered section of said steel alloy base material; A plurality of inserts are disposed within the plurality of pockets, wherein the plurality of inserts include an outer surface layer or coating selected from the group consisting of nanocrystalline diamond, amorphous diamond, diamond-like carbon, and mixtures thereof.

8. The expansion cone of claim 7, wherein the insert further comprises: a base material selected from the group consisting of alloy steel, alloy steel coated with tungsten carbide, and cemented tungsten carbide; and A buffer layer is deposited between the outer surface layer or coating and the insert base material, wherein the buffer layer is selected from the group consisting of silicon (Si), titanium (Ti), and silicon carbide (SiC).

9. An expansion cone according to claim 7 or claim 8, wherein the plurality of inserts are selected from the group consisting of unleached diamond-cobalt compacts, leached diamond-cobalt compacts, diamond-silicon compacts, binderless diamond compacts and diamond-boron nitride composite compacts.

10. An expansion cone according to any one of claims 7 to 9, wherein an upper surface of each of the plurality of inserts is 1 to 50 microns above an outer surface of the base material.

11. A method for forming an expansion cone for expanding an expandable tube, the method comprising: forming a base expansion cone from a material selected from the group consisting of alloy steel, alloy steel coated with tungsten carbide, and cemented tungsten carbide; depositing a buffer layer on at least the conical portion of the base expansion cone; and depositing a coating on the buffer layer; The buffer layer is formed of a material selected from another group consisting of silicon (Si), titanium (Ti) and silicon carbide (SiC).

12. The method of claim 11, further comprising depositing the buffer layer by physical vapor deposition (PVD) or chemical vapor deposition (CVD), and depositing the coating by CVD.

13. A method for forming an expansion cone for expanding an expandable tube, the method comprising: forming a base expansion cone having an upper cylindrical section, a lower cylindrical section, and a conical section therebetween; forming a plurality of recesses in the conical section of the basic expansion cone; A plurality of inserts are disposed within the plurality of pockets, wherein the plurality of inserts are selected from the group consisting of unleached diamond-cobalt compacts, leached diamond-cobalt compacts, diamond-silicon compacts, binderless diamond compacts, diamond-boron nitride composite compacts, and combinations thereof.

14. The method of claim 13, further comprising forming the plurality of inserts, the forming the plurality of inserts comprising: forming a base insert from a material selected from the group consisting of alloy steel, alloy steel coated with tungsten carbide, and cemented tungsten carbide; depositing a buffer layer on at least a portion of the base insert; and The outer surface layer or coating is deposited on the buffer layer.

15. The method of claim 13 or claim 14, wherein the plurality of inserts are disposed within each of the plurality of pockets by press fitting or brazing.

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