Corrosion-resistant and eccentric-wear-resistant coupling and sucker rod

Abstract

A first mounting groove is formed in the end face of a metal body, and a first circular bead and a second circular bead are formed on the portions, on the side wall of a first cavity, of the top and the bottom of the first mounting groove respectively; a first annular sealing groove is formed in the side wall of the first mounting groove, and the first fluororubber sealing ring is arranged in the first annular sealing groove; the two ends of the polytetrafluoroethylene connecting piece are a first connecting end and a second connecting end respectively, the first connecting end is in interference fit in the first mounting groove, and the second connecting end is used for being connected with a sucker rod; an annular boss is arranged on the outer side wall of the polytetrafluoroethylene connecting piece, and the two end faces of the annular boss abut against the first circular bead and the end face of the sucker rod connecting end in a clamped mode respectively. The sucker rod coupling can prevent well fluid from corroding the connecting part of the coupling and the sucker rod, is convenient to install, can prevent eccentric wear, and prolongs the service life of the sucker rod and the coupling.

Description

Technical Field

[0001] The utility model relates to a coupling and a sucker rod, in particular to a coupling and a sucker rod with anti-corrosion and anti-eccentric wear properties. Background Technique

[0002] In an oilfield drilling device, sucker rods are connected to each other through couplings. In a production well, hundreds of sucker rods need to be connected and lowered into the wellbore, and each sucker rod needs to be connected with a special sucker rod coupling. It goes deep into the underground oil well to pump out crude oil. Due to the complexity of the wellbore trajectory of a directional well, the original straight pipe string structure becomes a multi-directional bent pipe string. Therefore, during the production process of the oil well, the sucker rods in the wellbore will inevitably undergo eccentric wear with the tubing, especially at the connection part of the sucker rod coupling, where the wear is particularly serious. When the sucker rod coupling wears to a certain extent, the connection fails, resulting in the disconnection and breakage of the sucker rod, making the oil well unable to produce normally.

[0003] Under the production well, the composition of the well fluid is very complex, including oil, water, salt, acid and alkali, with strong corrosiveness. The coupling and the sucker rod are connected to each other through threads. Generally, the surface of the coupling has an anti-corrosion coating. However, due to the stress and long-term contact with the well fluid at the threaded connection, the coating is easy to fall off and is easy to be corroded. Especially when subjected to bending stress, the force is uneven, the local stress and deformation become larger, resulting in eccentric wear of the sucker rod, reducing the service life and the operation efficiency.

[0004] The application document of the Chinese utility model patent CN206000475U discloses an anti-corrosion device for the push-bearing surface of a sucker rod coupling and a sucker rod joint, and designs a cylindrical anti-corrosion device or a gasket-type cylindrical anti-corrosion device with symmetric grooves up and down and a circular hole in the center, which is installed at the push-bearing surface of the sucker rod and the coupling, and the end face of the anti-corrosion device is sealed by pressing the coupling and the sucker rod, and its function is similar to that of a sealing gasket, belonging to end face sealing. However, in the case of a bent sucker rod, gaps are likely to appear at the plastic-metal joint, resulting in the leakage of well fluid to the threaded part. The thermal shrinkage rates of plastic and metal are very different. When the well depth is relatively large, the temperature difference can reach about 200 °C, and the thermal expansion and contraction will also cause gaps at the plastic-metal joint. Therefore, it is difficult to ensure the sealing performance. Content of the Utility Model

[0005] The purpose of the utility model is to provide a coupling and a sucker rod with anti-corrosion and anti-eccentric wear properties, which solves the problem of poor sealing effect at the connection between the existing coupling and the sucker rod, can avoid the corrosion of the well fluid to the connection part of the coupling and the sucker rod, is easy to install, can prevent eccentric wear, and prolongs the service life of the sucker rod and the coupling.

[0006] To achieve the above object, the present utility model provides a coupling with anti-corrosion and anti-eccentric wear, which comprises: a metal body, a polytetrafluoroethylene connector and a first fluororubber sealing ring; the metal body and the polytetrafluoroethylene connector are located at the same position as the central axis of the sucker rod.

[0007] Wherein, the metal body has a through first cavity in the center, and first mounting grooves are opened on both end faces thereof. An internal thread is provided on the inner side wall of the first cavity close to the first mounting groove, and the internal thread is adapted to the external thread at the connection end of the sucker rod; a first shoulder and a second shoulder are respectively formed on the side wall of the first cavity at the top and bottom of the first mounting groove; a first annular sealing groove is opened on the side wall of the first mounting groove, and the first fluororubber sealing ring is arranged in the first annular sealing groove; the polytetrafluoroethylene connector has a through second cavity in the center, and its two ends are respectively a first connection end and a second connection end. The first connection end is press-fitted in the first mounting groove, and the second connection end is used for connecting with the sucker rod; an annular boss is arranged on the outer side wall of the polytetrafluoroethylene connector between the first connection end and the second connection end, and both end faces of the annular boss are respectively abutted against the first shoulder of the metal body and the end face of the connection end of the sucker rod; the end face of the first connection end of the polytetrafluoroethylene connector is abutted against the second shoulder.

[0008] Preferably, both the metal body and the polytetrafluoroethylene connector are of an annular cylindrical structure, and the annular boss is arranged around the circumference in the middle of the outer side wall of the annular cylindrical structure of the polytetrafluoroethylene connector.

[0009] Preferably, an internal thread is provided on the inner side wall of the first cavity.

[0010] Another object of the present utility model is to provide a sucker rod with anti-corrosion and anti-eccentric wear, which comprises: a sucker rod body and a second fluororubber sealing ring; the sucker rod body has a through third cavity in the center, and a connecting pipe is extended in the center of the connection end of the sucker rod body. An external thread adapted to the internal thread of the first cavity is provided on the outer side wall of the end of the connecting pipe; an annular second mounting groove is opened on the end face of the connection end of the sucker rod body around the circumference of the connecting pipe, and the second connection end of the polytetrafluoroethylene connector is in transitional fit with the second mounting groove; a second annular sealing groove is opened on the side wall of the second mounting groove, and the second fluororubber sealing ring is arranged in the second annular sealing groove.

[0011] The coupling with anti-corrosion and anti-eccentric wear and the sucker rod of the present utility model solve the problem of poor sealing effect at the connection between the existing coupling and the sucker rod, and have the following advantages:

[0012] (1) The present utility model belongs to axial sealing, and realizes sealing through the pre-compression of the sealing ring by the sealing groove, and is not affected by thermal expansion and contraction and bending;

[0013] (2) One end of the polytetrafluoroethylene connecting piece of the present utility model is connected by interference fit, and the other end is connected by transition fit to ensure that the sucker rod and the coupling will not rotate or slip when installed and connected.

[0014] (3) The present utility model uses a fluororubber sealing ring, which has high temperature resistance and corrosion resistance, and has high sealing reliability, and can effectively isolate the corrosion of well fluid. Description of the Drawings

[0015] Figure 1 It is a schematic connection diagram of the coupling and the sucker rod for anti-corrosion and anti-eccentric wear of the present utility model.

[0016] Figure 2 It is a schematic structural diagram of the metal body of the present utility model.

[0017] Figure 3 It is a schematic structural diagram of the polytetrafluoroethylene connecting piece of the present utility model.

[0018] Figure 4 It is a schematic structural diagram of the sucker rod of the present utility model. Detailed Embodiments

[0019] Next, the technical solutions in the embodiments of the present utility model will be described clearly and completely. Obviously, the described embodiments are only a part of the embodiments of the present utility model, rather than all the embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without making creative efforts shall fall within the protection scope of the present utility model.

[0020] It should be noted that: for those conditions not specified in the embodiments, they shall be carried out according to the conventional conditions or the conditions recommended by the manufacturer. For those reagents or instruments without indicating the manufacturer, they are all conventional products that can be obtained through commercial purchase.

[0021] Embodiment 1

[0022] An anti-corrosion and anti-eccentric wear coupling, see Figures 1 to 3 , including: a metal body 1, a polytetrafluoroethylene connecting piece 2 and a first fluororubber sealing ring 4. Among them, the polytetrafluoroethylene connecting piece 2 is arranged at the end face of the metal body 1.

[0023] Among them, the metal body 1 has a through first cavity at its center, and first mounting grooves are provided at both end faces thereof. A first shoulder and a second shoulder are respectively formed on the side wall of the first cavity at the top and bottom of the first mounting groove. A first annular sealing groove 3 is provided on the side wall of the first mounting groove, and a first fluororubber sealing ring 4 is arranged in the first annular sealing groove 3. The first fluororubber sealing ring 4 has high temperature resistance and corrosion resistance, and its sealing reliability is high, which can effectively isolate the corrosion of well fluid.

[0024] The inner side wall of the first cavity close to the first mounting groove has internal threads or the inner side walls of the first cavity all have internal threads, and the internal threads are adapted to the external threads at the connection end of the sucker rod.

[0025] The center of the polytetrafluoroethylene connector 2 has a through second cavity. The two ends of the polytetrafluoroethylene connector 2 are respectively a first connection end and a second connection end. Its first connection end is in interference fit in the first mounting groove. The first connection end is used to connect with the metal body 1, and the second connection end is used to connect with the sucker rod. An annular boss is arranged on the outer side wall of the polytetrafluoroethylene connector 2 between the first connection end and the second connection end, and the two end faces of the annular boss respectively abut against the first shoulder of the metal body 1 and the end face of the connection end of the sucker rod.

[0026] Specifically, both the metal body 1 and the polytetrafluoroethylene connector 2 are of annular cylindrical structures, and bosses are arranged around the circumference in the middle of the outer side wall of the annular cylindrical structure of the polytetrafluoroethylene connector 2. The polytetrafluoroethylene connector 2 has strong corrosion resistance, self-lubricating property and strong wear resistance.

[0027] Embodiment 2

[0028] A sucker rod with anti-corrosion and anti-eccentric wear, see Figure 1 、 4 , which is adapted to the coupling of Embodiment 1, and includes: a sucker rod body and a second fluororubber sealing ring 7.

[0029] Among them, the center of the sucker rod body has a through third cavity, and the center of the connection end of the sucker rod body has an extended connecting pipe. External threads adapted to the internal threads of the first cavity are provided on the outer side wall of the end of the connecting pipe. An annular second mounting groove 5 is provided on the end face of the connection end of the sucker rod body around the circumference of the connecting pipe. The second connection end of the polytetrafluoroethylene connector 2 is matched with the second mounting groove 5 and is in transitional fit.

[0030] A second annular sealing groove 6 is provided on the side wall of the second mounting groove 5, and a second fluororubber sealing ring 7 is arranged in the second annular sealing groove 6. The second fluororubber sealing ring 7 has high temperature resistance and corrosion resistance, and its sealing reliability is high, which can effectively isolate the corrosion of well fluid.

[0031] The using method of the sucker rod and the coupling with anti-corrosion and anti-eccentric wear of the present utility model is as follows:

[0032] In use, the first connection end of the polytetrafluoroethylene connector 2 is press-fitted into the first installation groove of the metal body 1, the connecting pipe of the sucker rod is inserted into the second cavity of the polytetrafluoroethylene connector 2, and the connecting pipe is threadedly connected to the metal body 1 by screwing. The second connection end of the polytetrafluoroethylene connector 2 is connected and fitted with the second installation groove 5 of the sealing groove of the sucker rod as an interference fit.

[0033] By connecting one end of the polytetrafluoroethylene connector 2 with an interference fit and the other end with an interference fit, it is ensured that the sucker rod will not rotate and slip when installed and connected to the coupling.

[0034] The sucker rod is a slender rod. In a deep well, several sucker rods are connected together by couplings. The sucker rod is prone to deformation and bending during operation, which causes the connection between the existing sucker rod and the coupling to be corroded by well fluid in a flexed or bent state. The present utility model designs a polytetrafluoroethylene connector at the connection end of the sucker rod and the coupling, and a fluororubber sealing ring is provided on the side walls of the first installation groove and the second installation groove 5. Through axial sealing, the contact between the threaded part and the well fluid is completely isolated, and it is not easily corroded by the well fluid. Moreover, for high temperatures underground, thermal expansion and contraction will also cause gaps at the plastic-metal joint. The sealing of the present utility model is axial sealing, and the sealing is achieved by pre-compressing the sealing ring through the sealing groove, which is not affected by thermal expansion and contraction and bending.

[0035] Although the content of the present utility model has been described in detail through the above preferred embodiments, it should be recognized that the above description should not be considered as a limitation of the present utility model. After those skilled in the art have read the above content, various modifications and substitutions to the present utility model will be obvious. Therefore, the protection scope of the present utility model should be defined by the appended claims.

Claims

1. A coupling for corrosion resistance and eccentric wear resistance, characterized in that: The coupling comprises: a metal body (1), a polytetrafluoroethylene connector (2) and a first fluororubber sealing ring (4); the metal body (1) and the polytetrafluoroethylene connector (2) are located at the same position as the central axis of the sucker rod; The center of the metal body (1) has a through first cavity, and the end surfaces of both ends are provided with first mounting grooves. The inner side wall of the first cavity close to the first mounting groove has an internal thread, and the internal thread is adapted to the external thread of the connecting end of the sucker rod; the top and bottom of the first mounting groove form a first shoulder and a second shoulder on the side wall of the first cavity respectively; A first annular sealing groove (3) is provided on the side wall of the first installation groove, and the first fluororubber sealing ring (4) is arranged in the first annular sealing groove (3); The center of the polytetrafluoroethylene connector (2) has a through second cavity, and two ends thereof are respectively a first connecting end and a second connecting end, wherein the first connecting end is interference-fitted in the first mounting groove, and the second connecting end is used to be connected to the sucker rod; An annular boss is provided on the outer wall of the polytetrafluoroethylene connector (2) between the first connecting end and the second connecting end, and the two end faces of the annular boss are respectively clamped against the first shoulder of the metal body (1) and the end face of the sucker rod connecting end; the end face of the first connecting end of the polytetrafluoroethylene connector (2) is clamped against the second shoulder.

2. The coupling according to claim 1, characterized in that: The metal body (1) and the polytetrafluoroethylene connector (2) are both annular cylindrical structures, and the annular boss is arranged around the circumference of the middle part of the outer side wall of the annular cylindrical structure of the polytetrafluoroethylene connector (2).

3. The coupling according to claim 1, characterized in that: The inner side wall of the first cavity is provided with an internal thread.

4. A corrosion-resistant and anti-eccentric wear sucker rod, characterized in that: The sucker rod comprises: a sucker rod body and a second fluororubber sealing ring (7); The sucker rod body has a third cavity at its center, and the connecting end of the sucker rod body has an extended connecting pipe at its center, and an outer wall of the end of the connecting pipe is provided with an outer thread matching the inner thread of the first cavity as described in claim 1; An annular second mounting groove (5) is provided on the end surface of the connecting end of the sucker rod body around the circumference of the connecting pipe, and the second connecting end of the polytetrafluoroethylene connector (2) as described in claim 1 is transitionally matched with the second mounting groove (5); A second annular sealing groove (6) is provided on the side wall of the second installation groove (5), and the second fluororubber sealing ring (7) is arranged in the second annular sealing groove (6).

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