Magnetic fisher for shaft

Abstract

The invention relates to the technical field of petroleum and natural gas underground cleaning equipment, in particular to a magnetic fisher for a shaft, which comprises a magnet, a spline connecting shaft and an elastic telescopic stop lever, first mounting grooves are formed in two sides of spline teeth of the spline connecting shaft, a second mounting groove is formed in the magnet, and the elastic telescopic stop lever is arranged in the second mounting groove. The elastic telescopic stop lever is arranged in the second mounting groove, the elastic telescopic stop lever and the magnet are clamped into the first mounting groove together, the stop lever positioning groove is used for limiting the elastic telescopic stop lever in the first mounting groove, and the magnet embedding groove is used for limiting the magnet in the first mounting groove and preventing the magnet from disengaging from the first mounting groove. The fisher adopts the elastic stop lever to fix the magnet, so that the magnetic strip is convenient to mount, the surface is not exposed and shielded, the flowing state of fluid in the magnet mounting groove is changed, and scrap iron is easier to capture.

Description

Technical Field

[0001] The invention relates to the technical field of oil and natural gas downhole cleaning equipment, in particular to a magnetic salvage device used in a wellbore. Background Art

[0002] The casing of oil and gas wells is a barrier that supports the wellbore and constitutes the oil and gas channel. During the drilling, completion and repair process, a large amount of iron filings remain in the casing due to the friction and wear between the joints of the operating pipe string and the inside of the casing, the window opening of the milling tool, and the explosion of the perforating tool. It is difficult to carry out of the wellbore through fluid circulation. The iron filings accumulate at the locations where the wellbore changes in diameter and the casing is deformed, which brings major safety hazards to the movement of the subsequent operating pipe string. In serious cases, it causes problems such as the pipe string twisting and the wellbore misalignment.

[0003] Magnetic salvage is a common tool for cleaning ferromagnetic debris. It is generally composed of a center shaft, a permanent magnet, a centralizer, etc. A spline is usually machined on the center shaft. The permanent magnet is in the shape of a long strip or a block. There are two ways to install it: ① The strip magnet is machined into a wedge shape and embedded in the dovetail groove of the center shaft spline protrusion, and the two ends are axially limited by the centralizer. Because the centralizer is connected to the center shaft by threads, the outer diameter of the centralizer is much larger than the spline part where the magnet is installed. Whether GB thread or ACME standard is used, limit pins must be installed on the threaded joint to prevent loosening during operation. The thread size in GB or ACME standards cannot be selected arbitrarily. The strength of the mandrel and the centralizer should be balanced, and the flow channel of the centralizer should be kept at a reasonable depth. After the limit pin installation hole is reserved, the outer diameter of the centralizer will inevitably be more than 20% larger than the center shaft. On the one hand, the increase in the size of the centralizer makes it more difficult to lower and pull the tool into and out of the wellbore. On the other hand, the fluid circulation space is reduced, and the iron chips carried by the fluid are not easy to pass through the centralizer. ②The block magnet is first installed in the stainless steel protective cover. The protective cover is in the shape of a long strip with 3-5 mounting holes evenly distributed on it. Screw the bolts into the mounting holes to fix the magnets on the central axis. There are generally 6-8 magnetic strips, and usually about 30 bolts are required. The ends of the bolts are exposed outside the magnet strips, and the exposed ends of the bolts become obstacles that are difficult to handle when cleaning debris. In order to control costs, the bolts are generally GB threads, and this type of thread has no anti-loosening measures. During operation, the magnetic salvage device is subjected to tension and torque, and constantly rubs and collides with the well wall. The magnetic salvage device vibrates continuously, which may cause the bolts to fall off, causing complex problems underground.

[0004] The whole magnetic steel is used to make a salvage device, such as a magnetic steel for salvage disclosed in the patent document (China Patent Publication No. CN108571296B), which is set as an integral unit, and the debris is stored and salvaged through the depression between the salvage wings. The two ends are connected to the tool through joints or stabilizers. The cost is too high and the fluid is not easy to flow. Summary of the invention

[0005] The purpose of the present invention is to provide a magnetic salvage device for a wellbore, which uses an elastic retaining rod to fix the magnet, is convenient for the installation of the magnetic strip, has no exposed surface and is unobstructed, changes the fluid flow state in the magnet installation groove, and makes iron filings easier to capture.

[0006] The purpose of the present invention can be achieved through the following technical solutions:

[0007] A magnetic salvage device for a wellbore comprises a magnet, a spline connecting shaft and an elastic telescopic baffle rod, wherein the spline teeth of the spline connecting shaft are provided with first mounting grooves on both sides, the first mounting grooves comprise a baffle rod positioning groove and a magnet embedding groove, the magnet is provided with a second mounting groove, the elastic telescopic baffle rod is provided in the second mounting groove and is inserted into the first mounting groove together with the magnet, the baffle rod positioning groove is used for limiting the elastic telescopic baffle rod in the first mounting groove, and the magnet embedding groove is used for limiting the magnet in the first mounting groove, so as to prevent the magnet from falling out of the first mounting groove.

[0008] In a further solution, the elastic telescopic blocking rod includes a first blocking rod, a spring and a second blocking rod which are arranged in sequence, and the first blocking rod and the second blocking rod are respectively inserted into the first installation groove under the action of the spring.

[0009] In a further embodiment, the spline tooth groove of the spline connecting shaft is wider at one end and narrower at the other end.

[0010] In a further embodiment, the width of the wide end of the spline teeth of the spline connecting shaft is twice that of the narrow end.

[0011] In a further embodiment, the magnet comprises a whole bar magnet, and the second mounting grooves are evenly distributed on the whole bar magnet.

[0012] In a further solution, the magnet includes a plurality of bar magnets, which are cold-embedded into a stainless steel shell, and are connected to the stainless steel shell by the elastic telescopic blocking rod so as to be inserted into the first mounting groove together.

[0013] In a further embodiment, the number of spline teeth of the spline connection shaft is greater than or equal to three.

[0014] In a further embodiment, the spline connection shaft is overall conical in shape.

[0015] In a further solution, a centralizer is integrally provided at the end of the spline connection shaft.

[0016] In a further solution, both ends of the spline connection shaft are provided with connection joints for connecting drill pipes and oil pipes.

[0017] Beneficial effects of the present invention:

[0018] The invention uses springs and baffles to install long magnets, without increasing the size of the centralizer or bolts. It is easier to maintain than conventional bolts, centralizers and other installation methods, and the installation speed is greatly improved. The overall size is compact and the annular flow channel is large. The magnet is long and has a larger effective area than ordinary magnets. The flow channel formed by the spline is a gradually expanding river channel, and the solid phase is easy to deposit during the flow of the fluid.

[0019] Long strip magnets can be used, which are about five times the volume of common button magnets, so the magnetic field strength is significantly enhanced.

[0020] The maximum outer diameter of the centralizer can be made small. For example, the maximum outer diameter of the centralizer is about 10% larger than that of the outer surface of the spline teeth. The centralizer can also be omitted, and the overall conical setting of the conical spline connecting shaft can be used as the centralizer to ensure that the overall outer diameter of the salvage device is small. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0022] Figure 1 It is a schematic diagram of the internal connection of a magnetic fishing device used in a wellbore in an embodiment of the present invention;

[0023] Figure 2 is a schematic diagram of a fluid passing through a spline connection shaft tooth groove in an embodiment of the present invention;

[0024] Figure 3 Schematic diagram of the connection between the whole bar magnet and the elastic telescopic blocking rod in an embodiment of the present invention;

[0025] In the figure: 1, magnet; 11, second mounting groove; 2, spline connecting shaft; 21, first mounting groove; 3, elastic telescopic blocking rod; 31, first blocking rod; 32, spring; 33, second blocking rod. DETAILED DESCRIPTION

[0026] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] like Figure 1As shown, a magnetic salvage device for a wellbore comprises a magnet 1, a spline connecting shaft 2 and an elastic telescopic blocking rod 3. The spline teeth of the spline connecting shaft 2 are provided with first mounting grooves 21 on both sides. The first mounting groove 21 comprises a blocking rod positioning groove and a magnet embedding groove. The blocking rod positioning groove is used to limit the elastic telescopic blocking rod 3 in the first mounting groove 21. The magnet embedding groove is used to limit the magnet 1 in the first mounting groove (21). The magnet 1 is provided with a second mounting groove 11. The elastic telescopic blocking rod 3 is arranged in the second mounting groove 11 and is inserted into the first mounting groove 21 together with the magnet 1 to prevent the magnet 1 from falling out of the first mounting groove 21.

[0028] Its working principle or implementation method is that by inserting a magnet into the spline connection shaft 2, not only can the use of magnets be reduced to save costs, but also it is easy to install. The magnetic salvage device does not contain moving parts, and the blocking rod is hidden in the second installation groove of the magnet. After the magnet is installed, compared with the bolt installation method, the end of the bolt is exposed outside the magnetic strip. After installation using an elastic telescopic blocking rod, it still presents a relatively complete plane shape, which is easy to clean the adsorbed iron filings. The overall structure is compact, the maximum outer diameter is small, and it is easy to lift and lower, which is suitable for deep wells and ultra-deep wells.

[0029] According to the above working principle, some preferred embodiments or implementation structures are provided. As shown in the figure, the elastic telescopic bar 3 includes a first bar 31, a spring 32 and a second bar 33 which are arranged in sequence. The first bar 31 and the second bar 33 are respectively inserted into the first mounting groove 21 under the action of the spring 32. In this way, the elastic telescopic bar 3 can be easily inserted into the first mounting groove 21. As long as the lengths of the first bar 31 and the second bar 33 and the stiffness of the spring 32 are reasonably set, the magnet 1 can be ensured not to fall out of the first mounting groove 21. After the bar is installed, it is completely hidden in the magnet. Those skilled in the art should be able to imagine that the first bar 31 and the second bar 33 can also be connected in a mutually sliding relationship.

[0030] like Figure 2 As shown, the spline tooth groove of the spline connection shaft 2 is wide at one end and narrow at the other end. The width of the wide end is equal to twice the width of the narrow end. When the circulating fluid flows through the magnet from bottom to top, because the flow channel below is small and the flow channel above is large, the Bernoulli equation shows that the flow velocity of the fluid in the flow channel slows down, the pressure increases slightly, and even eddies are generated locally, making it easier for iron filings to deposit at the corresponding position and be salvaged and carried out of the wellbore.

[0031] like Figure 3 As shown, the magnet 1 comprises a whole bar magnet 1, and the second mounting grooves 11 are evenly distributed on the whole bar magnet.

[0032] A person skilled in the art should be able to imagine that the magnet includes a plurality of bar magnets 1, which are cold-embedded into a stainless steel shell. A stainless steel shell in which the bar magnets 1 can be embedded is formed through sheet metal bending processing. The plurality of bar magnets are embedded in the stainless steel shell, and an elastic telescopic barrier rod 3 is connected to the stainless steel shell so as to be inserted into the first mounting groove 21 together.

[0033] The number of spline teeth of the spline connection shaft 2 is greater than or equal to three. Those skilled in the art should be able to imagine that the number of spline teeth can also be 4, 5 or 6.

[0034] The spline connecting shaft 2 is in a cone shape as a whole, so that the spline connecting shaft 2 itself can play a role in straightening and guiding during the process of going down into the well.

[0035] A centralizer is integrally arranged at the end of the spline connection shaft 2. In this way, the outer diameter of the centralizer is enlarged by about 10% compared with the spline position to play a good centralizing and guiding role.

[0036] Both ends of the spline connection shaft 2 are provided with connection joints for connecting drill pipes and oil pipes. The connection joints can be joint threads machined at both ends of the spline connection shaft 2, with a male buckle at the lower end and a female buckle at the upper end, both of which are standard drill pipe buckles or oil pipe buckles. The grooves between the splines are arranged at non-equidistant intervals, with the end close to the male buckle as the inlet, which is narrow in size; the end close to the female buckle as the outlet, which is wide in size. The flow channel cross section between the inlet and the outlet is gradually enlarged. An installation groove is milled on the spline, and a long strip magnet is installed in the groove, and the magnet is fixed in the installation groove by a spring retaining rod.

[0037] During installation, first carefully place the long magnet 1 into the first installation groove 21 on either side of the spline teeth of the spline connecting shaft 2, and then insert the first stopper 31, the spring 32 and the second stopper 33 into the second installation groove 11 one by one, and then directly push them into the first installation groove 21 after pressing. The first stopper 31 and the second stopper 33 are stuck between the inner wall of the first installation groove 21 and the magnet 1 under the action of the spring, and are blocked and limited by the outer side of the first installation groove 21. The elastic retractable stopper and the magnet are completely hidden, and there is no obvious protrusion or exposure on the outside.

[0038] See also Figure 3 When the circulating fluid flows from bottom to top through the spline groove of the spline connection shaft 2, since the lower flow channel is small and the upper flow channel is large, iron filings are more likely to be deposited at the corresponding position and be salvaged and carried out of the wellbore.

[0039] It should be noted that the terms "first", "second" etc. in the present application are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequential order. It should be understood that the data used in this way can be interchanged in appropriate circumstances, so that the embodiments of the present application described here. In the present application, the orientation or positional relationship indicated by the terms "upper", "lower", "left", "right", "front", "back", "top", "bottom", "inside", "outside", "middle", "vertical", "horizontal", "lateral", "longitudinal" etc. are based on the orientation or positional relationship shown in the accompanying drawings.

[0040] In the description of this specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0041] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, and these changes and improvements all fall within the scope of the present invention to be protected.

Claims

1. A magnetic fishing device for a wellbore, It is characterized in that The invention comprises a magnet (1), a spline connecting shaft (2) and an elastic telescopic blocking rod (3), wherein the spline teeth of the spline connecting shaft (2) are provided with first mounting grooves (21), the first mounting grooves (21) comprising blocking rod positioning grooves and magnet embedding grooves, the magnet (1) is provided with a second mounting groove (11), the elastic telescopic blocking rod (3) is arranged in the second mounting groove (11) and is inserted into the first mounting groove (21) together with the magnet (1), the blocking rod positioning groove is used for limiting the elastic telescopic blocking rod (3) in the first mounting groove (21), and the magnet embedding groove is used for limiting the magnet (1) in the first mounting groove (21).

2. A magnetic fishing device for a wellbore according to claim 1, It is characterized in that The elastic telescopic blocking rod (3) comprises a first blocking rod (31), a spring (32) and a second blocking rod (33) which are arranged in sequence, and the first blocking rod (31) and the second blocking rod (33) are respectively inserted into the blocking rod positioning groove under the action of the spring (32).

3. A magnetic fishing device for a wellbore according to claim 1, It is characterized in that The spline tooth groove of the spline connecting shaft (2) is wide at one end and narrow at the other end.

4. A magnetic fishing device for a wellbore according to claim 3, It is characterized in that The width of the spline tooth wide end of the spline connecting shaft (2) is equal to twice that of the narrow end.

5. A magnetic fishing device for a wellbore according to claim 1, It is characterized in that The magnet (1) comprises a whole bar magnet (1), and the second mounting grooves (11) are evenly distributed on the whole bar magnet.

6. A magnetic fishing device for a wellbore according to claim 1, It is characterized in that The magnets include a plurality of bar magnets (1), which are cold-inserted into a stainless steel housing and connected to the elastic telescopic blocking rod (3) on the stainless steel housing so as to be inserted into the first mounting groove (21) together.

7. A magnetic fishing device for a wellbore according to claim 1, It is characterized in that The number of spline teeth of the spline connection shaft (2) is greater than or equal to three.

8. A magnetic fishing device for a wellbore according to claim 1, It is characterized in that The spline connection shaft (2) is in a cone shape as a whole.

9. A magnetic fishing device for a wellbore according to claim 1, It is characterized in that A centralizer is integrally provided at the end of the spline connection shaft (2).

10. A magnetic fishing device for a wellbore according to claim 1, It is characterized in that Both ends of the spline connection shaft (2) are respectively provided with connection joints for connecting a drill pipe and an oil pipe.

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