Method and system for reducing friction in radial drilling operations and jet drilling operations

Abstract

A method for reducing friction in a radial drilling application is disclosed. The method includes coating at least one lubricant (70) inside a deflector shoe (52). Lubrication of the deflector shoe (52) can be achieved by applying a dry lubricant inside the deflector shoe, curing the dry lubricant, and then applying a wet lubricant on top of the cured dry lubricant. The inner surface (80) of the deflector shoe (52) may be roughened before application of the lubricant. The method may further include coating a hose (54) and / or a jet nozzle (64), and passing the hose and / or jet nozzle through the coated inside of the deflector shoe (52). The method may further include coating a milling part, and passing the milling part through the coated inside of the deflector shoe. An apparatus for reducing friction in a radial drilling application is also disclosed.

Description

Technical Field

[0001] The present invention relates to the operation of a deviated well / oil well / gas well apparatus from the surface. More specifically, the present invention relates to a deflector shoe used in a deviation operation. Even more specifically, the present invention relates to reducing friction in a deflector shoe.

Background Art

[0002] In hydrocarbon drilling operations where a drilling tool turns its orientation sideways through the side of a wellbore, a deviated well apparatus known as a "deflector shoe" is commonly used, which is attached to the lower end of a work string or production tube to "deflect" a case mill tool or a drilling tool sideways. When drilling multiple lateral boreholes from a wellbore, it is also common to operate the work string or production tube (hereinafter collectively referred to as the "tube" or "production tube") from the surface, for example, by rotating and / or raising and lowering the tube to operate an indexing device that rotates the deflector, thereby changing the orientation of the deflector device. In these methods, it is necessary to install an expensive, slow-moving, and / or difficult-to-move machine on the surface to lift the entire production tube.

[0003] One such indexing deflector device is described in the applicant's U.S. Patent No. 7,669,672.

[0004] FIG. 1 schematically shows such a prior art indexing deflector assembly, which typically includes a retractable tube anchor 22, a deflector shoe 20, an indexer tool 18, and a tube segment or connector or landing profile 17 for connecting the deflector shoe to the production tube 14. A milling tool or a drilling tool, for example, a jet nozzle 16a, descends through a coiled tube string 16 to be operably engaged with the deflector shoe 20. The tube 14 may be directly connected to the deflector shoe 20.

[0005] Details of such a deflector assembly are known to those skilled in the art and are not necessary for an understanding of the present invention. However, contextually, the tube anchor 22 is a device that mounts a slip device biased outwardly so as to "bite" into contact with the side wall of the wellbore casing 12. The tube anchor 22 is mechanically operated by rotation of the production tube 14 from the surface or hydraulically operated by fluid pressure. The deflector shoe 20 is a tubular component having a curved groove or passage 20a machined therethrough from its upper end, the groove entering from the upper end of the deflector shoe 20 having an orientation parallel to the major axis of the deflector shoe 20 and exiting from the side surface of the deflector shoe perpendicular to the major axis. The shoe 20 has its lower end connected to the indexer 18 and the tube anchor 22 and its upper end connected to the production tube 14. The indexing tool 18 changes the orientation of the deflector shoe 20 within the wellbore 10 in response to a combination of reciprocating up and down movement and rotation of the production tube 14, whereby case milling devices such as 16a and borehole drilling devices are connected to the deflector shoe 20 so as to change the radial direction in which they engage the wellbore casing 12 and the surrounding formation 11 through the deflector shoe 20 as its orientation changes.

[0006] The Applicant has developed a whipstock tube shift tool and method as shown in U.S. Patent No. 8,813,856 that overcomes the prior art problems associated with changing the orientation of a deflector device and reduces the time, cost, and difficulty associated with such a change in orientation. This is achieved by using hydraulic pressure and the tool to rotate the diverter shoe via an indexer.

[0007] Various patents have been issued in the past related to radial drilling and jet drilling applications, including several patents owned by the applicant. For example, U.S. Patent No. 9,145,738, issued on September 29, 2015, describes a method and apparatus for forming a borehole. This patent specifically discloses a jet nozzle for forming a borehole or removing other tubular formations, with a vibration-inducing mechanism that maximizes penetration rate and enlarges the diameter of the borehole. The vibration-inducing mechanism may be an internal turbine that responds to the flow of pressurized jet fluid through the nozzle. The nozzle has a forward opening that defines a swirling axial spray pattern of the fluid jet exiting the nozzle. The nozzle may also have a pointed tip configured to penetrate the formation. Vibration also reduces friction between the fluid supply hose and the borehole being penetrated and ejected by the nozzle. Systems and methods for forming a borehole using the jet nozzle are also disclosed.

[0008] U.S. Patent No. 8,590,637, issued on November 26, 2013, describes an apparatus and method for controlling the feed rate of a high-pressure hose in jet drilling operations. Specifically, this patent discloses a jet hose that is drawn into the tip of a tube string (coiled tube) for conveyance downhole and for jetting a lateral borehole from a main shaft. This apparatus allows the operator to sense the rate at which the jet hose and nozzle penetrate the formation and adjust the feed rate of the coiled tube string accordingly, thereby optimizing both the direction and length of the lateral borehole relative to the main shaft.

[0009] The first step of the two-step process of radial jet drilling is a casing milling process that utilizes the system described above and in FIG. 1 or an improved version thereof. This process is important to enable the nozzle of the jet drilling system to exit the casing and initiate cutting of the formation.

[0010] The second step of the radial jet excavation process is a water jet cutting process or a jet process. In this step, the assembly of the hose and the jet nozzle passes through the deflector shoe and changes its direction horizontally before emerging from the casing and cutting through the formation material.

[0011] From Figure 2, it can be seen how the jet nozzle 22 connected to the flexible hose 24 extends within the deflector shoe 20. When the jet nozzle 22 is pushed inside the deflector shoe 20, it necessarily contacts the wall of the deflector shoe 20. As shown in Figure 2, the flexible hose is connected to a plurality of sub - units 28 and ultimately to a coiled tube string 26 within the casing 12.

[0012] Figure 3 shows a prior - art example of a type of sampler nozzle sub - assembly that may be used in radial jet excavation operations. As can be seen from Figure 3, the sampler nozzle sub - assembly 30 includes a flexible hose 24 connected to a hose crimp 32, a turbine jet sub - unit 34, a rotor jet sub - unit 36, and finally a jet nozzle 22. Since several different types of jet nozzles and assemblies can be utilized in radial jet excavation operations, the amount of friction between each assembly and the inner wall of the deflector shoe will be different.

[0013] Ultimately, the friction between the components passing through the deflector shoe shortens the service life of the components and increases the power consumption of the motors and pumps used in these operations.

[0014] Accordingly, an object of the present invention is to provide a method for reducing friction in radial excavation applications and jet excavation applications.

[0015] Another object of the present invention is to provide a method for reducing the power consumption in radial jet excavation applications and jet excavation applications.

[0016] Another object of the present invention is to provide a method for extending the service life of each component used in radial drilling applications and jet drilling applications.

[0017] Another object of the present invention is to provide a method for reducing the costs and time associated with radial drilling applications and jet drilling applicant applications.

[0018] Yet another object of the present invention is to provide a method for reducing friction in radial drilling applications and jet drilling applications that is relatively simple and inexpensive.

[0019] Finally, an object of the present invention is to provide a method for reducing friction in radial drilling applications and jet drilling applications that is applicable in the field.

[0020] These and other objects and advantages of the present invention will become apparent upon reading the accompanying specification and claims.

Summary of the Invention

[0021] The present invention is a method for reducing friction in radial drilling applications, which includes coating at least one lubricant inside the deflector shoe. In one embodiment, the method includes applying a wet lubricant, which is a liquid mixed with a friction reducer, to the wellbore and inside the deflector shoe. The coating step may include applying a dry lubricant inside the deflector shoe, curing the applied dry lubricant, and applying a wet lubricant to the cured dry lubricant.

[0022] In one embodiment, the method further includes coating at least one lubricant on a hose and / or a jet nozzle, and passing the hose and / or the jet nozzle through the coated inside of the deflector shoe.

[0023] In one embodiment, the coating step includes coating the contact surface between the deflector shoe and the hose and / or the jet nozzle.

[0024] In one embodiment, the method further includes coating at least one lubricant on the milling part and passing the coated milling part through the coated inner side of the deflector shoe.

[0025] In one embodiment, the lubricant is selected from the group consisting of tire shine, fluoropolymer coating, tungsten disulfide coating, Never Seez (registered trademark), polytetrafluoroethylene, molybdenum disulfide, graphite, silicone, and epoxy.

[0026] In one embodiment, the method further includes roughening the inner side of the deflector shoe before the coating step. The roughening may be achieved by rubbing the inner side of the deflector shoe with sandpaper or by creating indentations on the surface in another way.

[0027] The present invention also relates to a method for reducing friction in radial drilling applications, the method including roughening the inner side of a deflector shoe, coating at least one lubricant on the inner side of the deflector shoe, passing a hose through the coated inner side of the deflector shoe, and applying a wet lubricant to the deflector shoe during the passing step.

[0028] In one embodiment, the at least one lubricant applied to the deflector shoe includes a cured dry lubricant having a wet lubricant layer thereon.

[0029] In one embodiment, the method further includes coating at least one lubricant on the outer side of the hose before the passing step.

[0030] In one embodiment, the method further includes coating at least one lubricant on the jet nozzle and passing the jet nozzle through the coated inner side of the deflector shoe.

[0031] In one embodiment, the method further includes coating at least one lubricant on the milling part and passing the coated milling part through the coated inner side of the deflector shoe.

[0032] The at least one lubricant may be selected from the group consisting of tire shine, fluoropolymer coating, tungsten disulfide coating, polytetrafluoroethylene, molybdenum disulfide, graphite, silicone, epoxy, and Never Seez®.

[0033] In one embodiment, the step of applying the wet lubricant is continuous during the excavation process, and the wet lubricant is a liquid mixed with a friction reducer.

[0034] The present invention is also a device for reducing friction in radial excavation applications. The device includes a deflector shoe having an inner surface and at least one lubricant applied to the inner surface of the deflector shoe. In one embodiment, the inner surface of the deflector shoe is roughened before the application of the at least one lubricant. In one embodiment, the at least one lubricant is a wet lubricant. In other embodiments, the at least one lubricant is a dry lubricant. In a preferred embodiment, the at least one lubricant is a cured dry lubricant having a wet lubricant layer thereon. The at least one lubricant may be selected from the group consisting of tire shine, fluoropolymer coating, tungsten disulfide coating, polytetrafluoroethylene, molybdenum disulfide, graphite, silicone, epoxy, and Never Seez®.

[0035] The foregoing description in this section is, among other things, intended to describe preferred embodiments of the present invention. It is understood that variations of this preferred embodiment can be made within the scope of the claims of this patent. Accordingly, this section should not be construed as limiting the broad scope of the present invention in any way. The present invention should be limited only by the following claims and their legal equivalents.

Brief Description of the Drawings

[0036] Figure 1 is a schematic view showing a prior art indexing deflector assembly with a deflector shoe.

[0037] Figure 2 is a schematic view of a jet drilling process showing a jet nozzle passed through a deflector shoe.

[0038] Figure 3 is an example of a prior art sampler nozzle subassembly used in a radial jet drilling operation.

[0039] Figure 4 shows the method and system of the present invention.

[0040] Figure 5 shows Graph 1, which shows that the test results indicate that the force required to pull a hose through a shoe increases as the internal pressure of the hose increases.

[0041] Figure 6 shows Graph 2, which shows how the required force changes depending on different coatings of the hose.

[0042] Figure 7 shows Graph 3, which shows the test results when the hose is coated with Never Seez (registered trademark).

[0043] Figures 8A and 8B show the interface between the hose and the surface of the deflector shoe at the microscopic level.

[0044] Figure 8C shows the interface between the hose and the deflector shoe when the surface of the deflector shoe is lubricated and roughened.

Best Mode for Carrying Out the Invention

[0045] Referring to Figure 4, a diagram of the system and method of the present invention is shown. The deflector shoe 52 is associated with the well casing 62. The deflector shoe 52 has an inner side through which the flexible hose 54 passes. The flexible hose 54 has a jet nozzle 64 at its tip. Figure 4 also shows a work tube 53 having a coil tube 56 inside. This is connected to the flexible hose 54 by a connector 58. Also shown in Figure 4 is a centralizer 60 that helps position the deflector shoe within the casing 62.

[0046] A lubricant coating 70 is provided on the inner side of the deflector shoe 52. As can be seen from Figure 4, the lubricant coating 70 is provided on the inner surface of the deflector shoe 52, and importantly, it is provided on the contact surfaces between the flexible hose 54, the jet nozzle 64, and the inner side of the deflector shoe 52. The lubricant coating 70 may include a wet lubricant, a dry lubricant, or a combination of the two.

[0047] In the case of a wet lubricant, the lubricant coating 70 may be applied manually by a field worker. In the case of a dry lubricant, the lubricant coating is preferably sprayed onto the inner side of the deflector shoe 52 or applied manually by other means.

[0048] As used herein, the term "wet lubricant" may be any lubricant that persists in a wet, liquid, or non-cured state. For example, wet lubricants include lubricants with low viscosity such as water, and relatively high-viscosity liquids such as greases or liquids with the consistency of a paste. A wet lubricant may also be a combination of wet lubricants such as water or other liquids containing a friction reducer introduced into the water. The friction reducer may be a polyacrylamide-based polymer.

[0049] The term "dry lubricant" includes lubricants that harden by heat treatment or due to the nature of the lubricant. In the hardened state, these dry lubricants form a surface with a lower coefficient of friction than the exposed metal surfaces of deflector shoes or other devices. By applying the dry lubricant to the device and heat-treating it or hardening it by other means before introduction into the wellbore, it can be made to remain on the device during operation.

[0050] In the present invention, the flexible hose 54 and the jet 64 may be coated with the same or a different lubricant coating to further reduce friction between the components. It is also within the scope of the concept of the present invention that the lubricant can be coated on the milling parts before passing through the lubricated deflector shoe 52.

[0051] In a preferred embodiment of the present invention, both the wellbore (casing 62) and the excavation device (i.e., the flexible hose 54, the jet 64, and the mill) are lubricated. The wet lubricant is applied from the surface into the excavation hole. The wet lubricant applied to the excavation hole is preferably a liquid containing powder (e.g., brine or water) and is applied continuously during the excavation operation. The wet lubricant may also contain a friction reducer added to the liquid treatment fluid continuously pumped into the wellbore.

[0052] In one embodiment, the dry lubricant is applied to the cutting device and the deflector shoe such that their surfaces are completely covered. Either an epoxy-based lubricant or a spray-coated lubricant can be applied. Once the dry lubricant has cured, it is preferable to apply a wet lubricant (such as a grease-type lubricant) on top of the cured dry lubricant. It has been found that such an additional coating of lubricant causes the lubricant to remain on the device for a longer period of time.

[0053] In the systems and methods of the present invention, several different commercially available lubricants can be utilized, including tire shine, fluoropolymer coatings, tungsten disulfide coatings, polytetrafluoroethylene, molybdenum disulfide, graphite, silicone, epoxy, and Never Seez®. Substances can be added to and modified in commercially available lubricants to enhance lubricity.

[0054] Tire shine is a variety of products that use special polymer technology to produce a glossy finish on the tire surface. Such polymer compounds are formulated not only to improve the appearance of the tire (due to the glossy finish) but also to protect the tire from harmful ultraviolet rays and contaminants accumulated on the road surface. Typically, tire shine is a silicone-based lubricant.

[0055] (BOSTIK's) Never-Seez® product line extends to a variety of anti-seize compounds suitable for a wide range of anti-seize, anti-galling, and lubrication applications. Special greases carry specific fine particles (mainly of metal) that protect components even in high-temperature, high-pressure, and corrosive environments, thereby reducing wear and allowing components to operate longer. Not all compounds are suitable for every application. Never-Seez® lubricants are known to contain graphite, copper flakes, aluminum powder, and zinc oxide.

[0056] The inventors' experiments have shown that treating the contact surface between the hose and the deflector shoe with a lubricant helps significantly reduce the force required to pull the hose through the deflector shoe. This has led to a reduction in the propulsion force required from the nozzle and the flow rate required for the nozzle itself to pull the hose. The maximum force required to pull a hose pressurized at 5600 psi through a deflector shoe was found to be reduced by 65% from 25 pound-feet when pulling a dry hose to 8 pound-feet when pulling a tire shine or oil-coated hose through a shoe coated with Never Seez (registered trademark).

[0057] The inventors conducted experiments using combinations of wet lubricants, which are detailed below. First, a pull-through shoe test was conducted. Specifically, the force required to pull a pressurized hose through shoes with different surface conditions was tested. This test was conducted to analyze how much force is required to pull the hose through the deflector shoe by varying the pressure magnitude at different surface conditions. The hose was placed between two steel deflector shoe pieces. The hose was pulled out at a continuous speed, and the maximum force required was recorded. The tests were conducted in various hose conditions, namely, (1) a dry hose, (2) a hose wet with water, (3) a dry hose through a shoe piece coated with a commercially available lubricant, and (4) an oil-coated hose through a shoe piece coated with a commercially available lubricant. Commercially available hoses were used. In this test, the commercially available lubricant was Never Seez (registered trademark).

[0058] The test results are shown in Graph 1 (see Figure 5). Graph 1 shows that the force required to pass the hose through the shoe increases as the internal pressure of the hose increases. The maximum pressure applied to the hose was 5600 p.s.i. However, by lubricating the surface of the hose, the required tensile force is reduced by approximately 50% from the case of using a dry hose to the case of using an oil-coated hose and a shoe coated with a commercially available lubricant.

[0059] By reducing the friction on the hose, more force can be effectively transmitted. Further experiments were conducted using different coatings. Graph 2 (see Figure 6) shows three additional conditions, namely, (5) when the hose coated with tire shine was passed through the deflector shoe, (6) when the hose coated with tire shine and oil was passed through the deflector shoe, and (7) when the hose coated with tire shine and oil was passed through the shoe coated with Never Seez (registered trademark). It was found that the maximum force required to pull a 5600 p.s.i. hose through the deflector shoe decreased from 8.4 lbft for the tire in condition (7), that is, when the hose coated with tire shine and oil was passed through the shoe coated with Never Seez (registered trademark).

[0060] Also, as shown in Graph 3 (see Figure 7), when the hose was coated with Never Seez (registered trademark), a difference occurred in the average force required to pull the hose through the deflector shoe.

[0061] The experiments detailed above were conducted using wet lubricants that can be applied by hand. Further experiments have shown that dry lubricants are also likely to adhere to the inside of the deflector shoe over time, thereby maintaining a reduction in friction. These dry lubricants can be sprayed or applied by hand and dried and / or heat-treated, and can also be used for a longer period. The inventors expect similar or better results for dry lubricants from the perspective of the difference in tensile force.

[0062] The present invention may also include the step of roughening the surface of the deflector shoe 52, and in the case of an apparatus or system, a roughened deflector shoe 62 may be provided. FIG. 8A shows the interface between the metal surface 80 of the deflector shoe 62 and the irregular surface 82 of the rubber hose at the microscopic level. FIG. 8B shows the interface when the hose is stretched and pressurized. From FIG. 8B, it can be seen how the flattened surface 82 of the hose abuts against the metal surface 80. This mode may generate a vacuum between their surfaces and cause a higher resistance force. The vacuum is generated between the contact points of the hose and the metal surface 80. An increase in the resistance force may also be caused by an increase in the contact area between the surfaces.

[0063] As a solution to this problem, in the present invention, the originally smooth and shiny metal surface of the deflector shoe may be roughened before installation and lubricant coating. Roughening can be achieved by several methods including polishing with various grades of sandpaper. The rough surface 80 may also be generated by creating depressions on the surface in another way.

[0064] The obtained rough surface 80 is shown in FIG. 8C. As can be seen, the effect of the rough surface 80 is that grooves are generated to release air and fluid, thereby releasing the vacuum. It was found that the generation of the grooves reduces the resistance force against the hose. The wet and / or dry lubricants applied to the hard hose reduce deformation, and the wet lubricant applied to the shaft further reduces the deformation of the hose and the friction between the surfaces. The rough surface 80 also improves the application and retention of the lubricant.

[0065] The method and system of the present invention can significantly reduce the friction between the excavation parts and the deflector shoe. As a result, the service life of the parts involved in these operations is prolonged. Furthermore, the reduction in friction enables a reduction in the power consumption of the equipment used to operate the tools in the excavation operation, contributing to a reduction in the costs involved in such operations.

[0066] The above disclosure and description of the present invention are for illustrative and explanatory purposes of the invention. Various changes in the details of the illustrated structure can be made within the scope of the present invention without departing from the true spirit of the present invention.

Claims

**Claim 1** A method for reducing friction in radial drilling applications, comprising coating at least one lubricant on the inside of the deflector shoe. **Claim 2** The method according to claim 1, further comprising applying a wet lubricant, which is a liquid mixed with a friction reducer, to the inside of the shaft and the deflector shoe. **Claim 3** The coating step comprises applying a dry lubricant to the inside of the deflector shoe, curing the applied dry lubricant, and applying a wet lubricant on top of the cured dry lubricant, the method according to claim 1. **Claim 4** coating at least one lubricant on a hose, and passing the hose through the coated inside of the deflector shoe, the method according to claim 1. **Claim 5** coating at least one lubricant on a jet nozzle, and passing the jet nozzle through the coated inside of the deflector shoe, the method according to claim 1. **Claim 6** coating at least one lubricant on a milling part, and passing the milling part through the coated inside of the deflector shoe, the method according to claim 1. **Claim 7** The at least one lubricant is selected from the group consisting of tire shine, fluoropolymer coating, tungsten disulfide coating, polytetrafluoroethylene, molybdenum disulfide, graphite, silicone, epoxy, and Never Seez® , the method according to claim 1. **Claim 8** The method according to claim 1, further comprising roughening the inside of the deflector shoe before the coating step. **Claim 9** The roughening step comprises sanding the inside of the deflector shoe with sandpaper, the method according to claim 8. **Claim 10** A method for reducing friction in radial drilling applications, comprising roughening the inside of the deflector shoe, coating at least one lubricant on the inside of the deflector shoe, passing a hose through the coated inside of the deflector shoe, and applying a wet lubricant to the deflector shoe during the passing step. **Claim 11** The method according to claim 10, wherein at least one lubricant applied to the deflector shoe comprises a cured dry lubricant having a wet lubricant layer thereon.

12. The method according to claim 10, further comprising coating at least one lubricant on the outside of the hose before the passing step.

13. Coating at least one lubricant on a jet nozzle, and The method according to claim 10, further comprising passing the jet nozzle through the coated inner side of the deflector shoe.

14. Coating at least one lubricant on a milling part, and The method according to claim 10, further comprising passing the milling part through the coated inner side of the deflector shoe.

15. The method according to claim 10, wherein the at least one lubricant is selected from the group consisting of tire shine, fluoropolymer coating, tungsten disulfide coating, polytetrafluoroethylene, molybdenum disulfide, graphite, silicone, epoxy, and Never Seez (registered trademark).

16. The step of applying the wet lubricant is continuous during the excavation process, and the wet lubricant is a liquid mixed with a friction reducer. The method according to claim 10.

17. An apparatus for reducing friction in a radial excavation application, comprising: A deflector shoe having an inner surface; and An apparatus comprising at least one lubricant applied to the inner surface of the deflector shoe.

18. The apparatus according to claim 17, wherein the inner surface of the deflector shoe is roughened before the application of the lubricant.

19. The apparatus according to claim 17, wherein the at least one lubricant comprises a cured dry lubricant having a wet lubricant layer thereon.

20. The apparatus according to claim 17, wherein the at least one lubricant is selected from the group consisting of tire shine, fluoropolymer coating, tungsten disulfide coating, polytetrafluoroethylene, molybdenum disulfide, graphite, silicone, epoxy, and Never Seez (registered trademark).

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