Air-tight seal structure of oil casing

Abstract

The utility model relates to the technical field of sealing connection of pipe fittings, in particular to an air-tight sealing structure of an oil casing. Comprising a pipe fitting and a coupling, external threads are machined on a connecting section of the pipe fitting, internal threads are machined on a connecting section of the coupling, an external bevel contact surface and an internal bevel contact surface are machined at the end of the pipe fitting and in the coupling respectively, an annular groove is formed in the portion, on the outer side of the internal bevel contact surface, of the coupling, the section of the annular groove is in an inverted-L shape, and a sealing ring is installed in the annular groove. The outer bevel angle contact face is in sealing contact with the sealing ring, an upper flange is arranged at the upper end of the sealing ring, a side flange is arranged on the inner edge face, away from the inner thread, of the sealing ring, an upper groove and a side groove are formed in the groove wall of the annular groove, the upper flange is clamped in the upper groove, and the side flange is clamped in the side groove. The upper flange and the side flange of the sealing ring are clamped into the upper groove and the side groove of the annular groove respectively, so that bidirectional mechanical locking is formed, and the sealing ring is prevented from being separated from the annular groove due to vibration or pressure fluctuation.

Description

TECHNICAL FIELD

[0001] The utility model relates to a kind of pipe sealing connection technical field, specifically to a kind of oil casing gas seal structure. BACKGROUND

[0002] With the increase of buried depth of oil reservoir, the drilling and production conditions of oil are increasingly harsh, the load conditions of oil well pipe column are more and more complex, and the failure of oil well pipe threaded joint has become one of the main problems encountered by each oil field. The present application is to solve the problem of failure of threaded joint in ultra-deep gas well.

[0003] In the oilfield oil casing leakage and fracture accidents, the failure position is mostly at the oil pipe joint thread, stress and corrosion are the main reasons for the oil pipe fracture, and the different degrees of sticking in the oil pipe during the upper and lower opening lead to the threaded seal failure of the oil casing in the ultra-deep well.

[0004] A patent document with the application number CN200820222272.6 and the name "Threaded connection structure of oil well tubing or gas well casing" discloses a threaded connection structure with simple structure and good sealing performance. The main sealing structure is designed as an inner sealing cone surface and an outer sealing spherical surface, and the outer sealing spherical surface is smoothly transitioned, so that the sealing structure is easier to cooperate, the contact pressure distribution on the main sealing surface is uniform, and therefore the internal fluid of the casing can be effectively sealed. By setting a sealing groove and adding a sealing ring to engage with the outer thread, the elastic sealing structure is increased, and the external fluid of the casing can be effectively sealed. Not only can the internal fluid be sealed, but also the fluid from the outside of the casing can be sealed, and the sealing reliability is greatly increased, and the gas sealing resistance can reach the yield pressure of the inner wall of the pipe body. In the patent, a Teflon sealing ring is installed in the sealing groove of the coupling, and after tightening, the outer thread, outer sealing surface and outer shoulder on the pipe body form an interference fit with the inner thread, Teflon sealing ring, inner sealing cylindrical surface, inner sealing cone surface and inner shoulder on the coupling. After the inner and outer threads are engaged with each other, the two parts are connected together to ensure the connection strength of the joint part. The outer shoulder tightly contacts with the inner shoulder of the coupling to position the two components and prevent the interference amount of the inner and outer threads from being too large; the outer sealing surface on the pipe body and the inner sealing surface on the coupling form an interference fit, which can seal the internal pressure of the pipe body and prevent the fluid in the casing from leaking. At the same time, the outer thread teeth tightly embed the Teflon sealing ring in the sealing groove, the leakage channel is blocked, and the external pressure of the pipe body can be sealed to prevent the fluid outside the casing from entering the casing string. During the connection of the tubing, the tubing on the pipe rack is lifted by the pneumatic winch and clamped by the hydraulic tongs, and then the tubing clamped by the hydraulic tongs is connected with the coupling of the tubing in the well to form a tubing string. During the connection of the lifted tubing and the coupling of the tubing in the well, the tubing end sealing surface is easily scratched, i.e. the outer sealing cylindrical surface and the outer shoulder in the above patent are easily collided to cause sealing failure, which causes the scratched outer sealing cylindrical surface and the outer shoulder to be unable to effectively seal with the inner sealing cylindrical surface, the inner sealing cone surface and the inner shoulder on the coupling. During the operation of the tubing string, well fluid easily enters between the outer thread and the inner thread, which causes the inner thread and the thread to be corroded, thereby reducing the service life of the tubing. Therefore, it is necessary to optimize the threaded connection structure of the tubing and the coupling.

[0005] In order to solve the above technical problems, the patent file with publication number CN221799695U discloses an oil casing gas-tight joint, which comprises a tubing and a coupling, an outer thread, an outer sealing surface and an outer bevel contact surface are sequentially processed on the connecting section of the tubing, an inner thread, an inner sealing surface and an inner bevel contact surface are sequentially processed on the connecting section of the coupling, the outer sealing surface and the inner sealing surface are correspondingly arranged, the outer sealing surface comprises an outer taper surface and an outer sealing cylindrical surface connected with each other, the inner sealing surface comprises an inner taper surface and an inner sealing cylindrical surface connected with each other, the inner thread and the outer thread are threadedly connected, the inner taper surface and the outer taper surface are interference-fitted, the inner sealing cylindrical surface and the outer sealing cylindrical surface are interference-fitted, the outer bevel contact surface and the inner bevel contact surface are interference-fitted, a ring groove with an inverted L-shaped cross section is formed at the connecting position of the inner sealing cylindrical surface and the inner bevel contact surface, a combined rubber ring is arranged in the ring groove, and the outer sealing cylindrical surface and the outer bevel contact surface are in sealing contact with the combined rubber ring. By arranging the combined rubber ring, when the sealing surface at the end of the tubing is damaged, the sealing performance of the tubing and the coupling after being connected can be ensured. After the tubing and the coupling are connected, the inner sealing ring can be in sealing contact with the outer sealing cylindrical surface and the outer bevel contact surface, and two sealing surfaces can be increased by the inner sealing ring. The sealing effect of the tubing and the coupling is improved. However, the combined rubber ring is arranged in the ring groove, and is only limited by the upper groove wall of the ring groove, so the combined rubber ring is easy to be taken out of the ring groove. Practical new type content

[0006] The main purpose of the utility model is to provide an oil casing gas-tight sealing structure which has good sealing performance, can avoid the outer thread of the tubing and the inner thread of the coupling from being in contact with well fluid, can effectively protect the inner thread and the outer thread, and can improve the service life of the coupling and the tubing.

[0007] In order to achieve the above purpose, the technical scheme provided by the utility model is:

[0008] An oil casing gas-tight sealing structure, which comprises a tubing and a coupling, an outer thread is processed on the connecting section of the tubing, an inner thread is processed on the connecting section of the coupling, the inner thread and the outer thread are threadedly connected, an outer bevel contact surface and an inner bevel contact surface are respectively processed on the end of the tubing and the inner of the coupling, the outer bevel contact surface and the inner bevel contact surface are interference-fitted, a ring groove is formed on the outer side of the inner bevel contact surface of the coupling, the cross section of the ring groove is in an inverted L shape, a sealing ring is arranged in the ring groove, the outer bevel contact surface is in sealing contact with the sealing ring, an upper flange is arranged at the upper end of the sealing ring, a side flange is arranged on the inner edge surface of the sealing ring away from the inner thread, an upper groove and a side groove are formed on the groove wall of the ring groove, the upper groove corresponds to the upper flange, the side groove corresponds to the side flange, the upper flange is clamped in the upper groove, and the side flange is clamped in the side groove.

[0009] Specific, the connecting section of the pipe is processed with an outer closed surface and an outer bevel contact surface, the connecting section of the coupling is processed with an inner closed surface and an inner bevel contact surface, the outer closed surface and the inner closed surface are correspondingly arranged, the outer closed surface comprises an outer taper surface and an outer sealing cylindrical surface connected with each other, the inner closed surface comprises an inner taper surface and an inner sealing cylindrical surface connected with each other, the inner taper surface and the outer taper surface are in interference fit, and the inner sealing cylindrical surface and the outer sealing cylindrical surface are in interference fit.

[0010] Specific, the outer sealing cylindrical surface is in sealing contact with the sealing ring.

[0011] Specific, the upper groove wall of the ring groove is an upper taper surface, the upper taper surface is inclined to the inner thread direction, the upper end surface of the sealing ring is an upper fitting taper surface, the upper fitting taper surface is fitted with the upper taper surface, and the upper groove is arranged on the upper taper surface.

[0012] Specific, the inner edge surface of the sealing ring close to the inner thread is a sealing taper surface, the sealing taper surface is inclined to the coupling center direction at the end far from the inner thread, and the sealing taper surface is equal in diameter to the end opposite to the inner sealing cylindrical surface.

[0013] Specific, the inner edge surface of the sealing ring far from the inner thread is a side fitting taper surface, the groove wall of the ring groove close to the coupling shaft center is a side taper surface, the side taper surface is inclined to the coupling outer side direction at the end close to the inner thread, the side fitting taper surface is fitted with the side taper surface, and the side groove is arranged on the side taper surface.

[0014] Specific, the sealing ring is internally provided with a rib ring with a reverse L-shaped section, the rib ring is made of elastic material, one end of the rib ring extends into the upper flange, and the other end of the rib ring extends into the side flange.

[0015] Specific, the rib ring is made of PVC material.

[0016] Compared with the prior art, the utility model has the advantages of:

[0017] 1. The upper flange and the side flange of the sealing ring are respectively clamped into the upper groove and the side groove of the ring groove, thereby forming bidirectional mechanical locking and avoiding the vibration or pressure fluctuation of the sealing ring from the ring groove.

[0018] 2. The interference fit between the outer sealing cylindrical surface and the sealing taper surface forms the first sealing, the interference fit between the outer bevel contact surface and the sealing ring forms the second sealing, and the interference fit between the inner taper surface and the outer taper surface and the inner sealing cylindrical surface and the outer sealing cylindrical surface provides the third and fourth sealing. The four redundant sealing layers can guarantee the overall sealing property even if the oil pipe end sealing surface is locally damaged due to knocking, and the air sealing pressure strength is more than 90% of the yield pressure of the pipe body, and is suitable for the high pressure and high temperature environment of super deep well.

[0019] 3. The outer bevel contact surface and the inner bevel contact surface are used as the main bearing structure, thereby reducing the stress concentration of the thread engagement area.

[0020] 4. The sealing ring is embedded with a reversed L-shaped PVC ring at the inside, which extends to the upper flange at one end and to the side flange at the other end. The ring provides elastic support, enabling the sealing ring to be moderately deformed to adapt to the ring groove during installation, while enhancing the shear resistance of the flange.

[0021] 5. The upper groove wall of the ring groove is designed as an upper taper surface, which matches the upper matching taper surface of the sealing ring; the side taper surface of the ring groove wall matches the side matching taper surface of the sealing ring. The taper surface matching forms a progressive compression, which automatically corrects the position of the sealing ring during assembly, reducing installation deviation. The inclined taper surface generates a radial force under high pressure, further enhancing the adhesion of the sealing ring to the groove wall. Therefore, the assembly efficiency is improved, and the uniformity of the sealing surface contact pressure distribution is improved. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 is a sectional view of the pipe and the coupling in a split structure.

[0023] Figure 2 is Figure 1 is an enlarged view of area A.

[0024] Figure 3 is a sectional view of the pipe and the coupling after being connected.

[0025] Figure 4 is Figure 3 is an enlarged view of area B.

[0026] Figure 5 is a partial structural sectional view of the coupling.

[0027] Figure 6 is Figure 5 is an enlarged view of area C.

[0028] Figure 7 is a sectional view of the sealing ring.

[0029] Figure 8 is Figure 7 is an enlarged view of area D.

[0030] The names of the components in the drawings are as follows: 1, external thread, 2, internal thread, 3, external sealing cylindrical surface, 4, internal sealing cylindrical surface, 5, external bevel contact surface, 6, internal bevel contact surface, 7, external taper surface, 8, internal taper surface, 9, coupling, 10, pipe, 11, sealing ring, 12, ring, 13, ring groove, 14, upper groove, 15, side groove, 16, upper flange, 17, side flange, 18, upper taper surface, 19, side taper surface, 20, upper matching taper surface, 21, side matching taper surface, 22, sealing taper surface. DETAILED DESCRIPTION

[0031] The technical solutions in the embodiments of the utility model will be clearly and completely described below with reference to the drawings in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, rather than all the embodiments.

[0032] Embodiment one: refer to Figures 1-8 As shown in figure 1, a kind of oil casing gas seal structure, including pipe fittings 10 and coupling 9, the connecting section of pipe fittings 10 is processed with outer thread 1, the connecting section of coupling 9 is processed with inner thread 2, inner thread 2 and outer thread 1 are threadedly connected, the end of pipe fittings 10 and the inner of coupling 9 are respectively processed with outer bevel contact surface 5 and inner bevel contact surface 6, outer bevel contact surface 5 and inner bevel contact surface 6 are interference fit, ring groove 13 is set up on the coupling 9 outside of inner bevel contact surface 6, the section of ring groove 13 is inverted L shape, sealing ring 11 is installed in ring groove 13, outer bevel contact surface 5 and sealing ring 11 sealing contact, the upper end of sealing ring 11 is provided with upper flange 16, the inner edge surface of sealing ring 11 away from inner thread 2 is provided with side flange 17, upper recess 14 and side recess 15 are set up on the groove wall of ring groove 13, upper recess 14 corresponds with upper flange 16, side recess 15 corresponds with side flange 17, upper flange 16 is clamped in upper recess 14, side flange 17 is clamped in side recess 15.

[0033] The connecting section of pipe fittings 10 is processed with outer closed surface and outer bevel contact surface 5, the connecting section of coupling 9 is processed with inner closed surface and inner bevel contact surface 6, outer closed surface and inner closed surface are correspondingly arranged, outer closed surface includes outer taper surface 7 and outer sealing cylinder surface 3 connected, inner closed surface includes inner taper surface 8 and inner sealing cylinder surface 4 connected, inner taper surface 8 and outer taper surface 7 are interference fit, inner sealing cylinder surface 4 and outer sealing cylinder surface 3 are interference fit.The outer sealing cylinder surface 3 and sealing ring 11 sealing contact.

[0034] The upper groove wall of ring groove 13 is upper taper surface 18, upper taper surface 18 outer side is inclined to inner thread 2 direction, the upper end surface of sealing ring 11 is upper fit taper surface 20, upper fit taper surface 20 is fitted with upper taper surface 18, upper recess 14 is set up on upper taper surface 18.

[0035] The inner edge surface of sealing ring 11 close to inner thread 2 is sealing taper surface 22, the end of sealing taper surface 22 away from inner thread 2 is inclined to the center direction of coupling 9, the diameter of the end of sealing taper surface 22 opposite to inner sealing cylinder surface 4 is equal.

[0036] The inner edge surface of sealing ring 11 away from inner thread 2 is side fit taper surface 21, the groove wall of ring groove 13 close to the axis of coupling 9 is side taper surface 19, the end of side taper surface 19 close to inner thread 2 is inclined to the outside direction of coupling 9, side fit taper surface 21 is fitted with side taper surface 19, side recess 15 is set up on side taper surface 19.

[0037] After the sealing ring 11 is installed into the ring groove 13, the upper flange 16 is clamped into the upper groove 14, and the side flange 17 is clamped into the side groove 15. Due to the fact that the upper taper surface 18 is inclined outwardly toward the inner thread 2, the upper end surface of the sealing ring 11 is an upper abutting taper surface 20, the upper abutting taper surface 20 abuts against the upper taper surface 18, and the side taper surface 19 is inclined outwardly from the end close to the inner thread 2 toward the outside of the coupling 9, and a side abutting taper surface 21 abuts against the side taper surface 19. The upper taper surface 18 and the side taper surface 19 can clamp the sealing ring 11, and the stability of the sealing ring 11 in the ring groove 13 can be improved.

[0038] After the pipe fitting 10 is connected to the coupling 9, the interference fit of the inner taper surface 8 and the outer taper surface 7, the interference fit of the inner sealing cylindrical surface 4 and the outer sealing cylindrical surface 3, and the interference fit of the outer bevel contact surface 5 and the inner bevel contact surface 6 can enable the pipe fitting 10 and the coupling 9 to be sealingly connected.

[0039] After the outer bevel contact surface 5 and the inner bevel contact surface 6 are sealingly abutted, the interference amount of the inner thread 2 and the outer thread 1 can be effectively prevented from being too large to cause damage to the inner thread 2 and the outer thread 1.

[0040] During the connection of the pipe fitting 10 and the coupling 9, the outer sealing cylindrical surface 3 can be in sealing contact with the sealing taper surface 22 of the sealing ring 11. Since the diameter of the end of the sealing taper surface 22 opposite to the inner sealing cylindrical surface 4 is equal, during the rotation of the pipe fitting 10 into the coupling 9, the outer sealing cylindrical surface 3 can be smoothly in sealing contact with the sealing taper surface 22, and as the pipe fitting 10 is continuously rotated into the coupling 9, the extrusion force of the outer sealing cylindrical surface 3 on the sealing taper surface 22 gradually increases.

[0041] As the pipe fitting 10 is continuously rotated into the coupling 9, the interference fit of the outer bevel contact surface 5 and the inner bevel contact surface 6 is completed, and at this time, the outer bevel contact surface 5 is in abutment with the sealing ring 11, and the outer bevel contact surface 5 is in sealing contact with the sealing ring 11.

[0042] When the sealing surface of the end of the pipe fitting 10 is damaged, the sealing performance of the pipe fitting 10 and the coupling 9 after being connected can be ensured. After the pipe fitting 10 and the coupling 9 are connected, the sealing ring 11 can be in sealing contact with the outer sealing cylindrical surface 3 and the outer bevel contact surface 5, and two sealing surfaces can be increased by the sealing ring 11, and the sealing effect of the pipe fitting 10 and the coupling 9 is improved.

[0043] Example Two: Based on Example One, referring to Figure 7 and Figure 8As shown, the sealing ring 11 is provided with a rib ring 12 in inverted L-shaped cross section, the rib ring 12 is made of elastic material, one end of the rib ring 12 extends into the upper flange 16, the other end of the rib ring 12 extends into the side flange 17. The rib ring 12 is made of PVC material. The elastic support of the rib ring 12 can offset the deformation of the sealing ring 11 under high pressure. The rib ring 12 maintains the geometric stability of the sealing ring 13 under high pressure, avoids the upper flange 16 from being separated from the upper groove 14 and the side flange 17 from being separated from the side groove 15 due to deformation, and can compensate for the wear of the sealing surface.

[0044] By arranging the rib ring 12, the structural strength of the sealing ring 11 can be improved. The rib ring 12 is made of elastic material, which ensures that the sealing ring 11 can be deformed and installed in the ring groove 13.

[0045] One end of the rib ring 12 extends into the upper flange 16, and the other end of the rib ring 12 extends into the side flange 17, which can improve the structural strength of the upper flange 16 and the side flange 17, and can avoid the upper flange 16 from being easily withdrawn from the upper groove 14 and the side flange 17 from being easily withdrawn from the side groove 15. The stability of the sealing ring 11 in the ring groove 13 is further improved.

[0046] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. Any modification, equivalent replacement and improvement within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A gas-tight structure for an oil casing, comprising a pipe fitting (10) and a coupling (9), wherein an external thread (1) is machined on the connecting section of the pipe fitting (10), and an internal thread (2) is machined on the connecting section of the coupling (9), the internal thread (2) and the external thread (1) are threaded together, an external oblique angle contact surface (5) and an internal oblique angle contact surface (6) are respectively machined on the end of the pipe fitting (10) and the inside of the coupling (9), the external oblique angle contact surface (5) and the internal oblique angle contact surface (6) are interference fit, an annular groove (13) is provided on the coupling (9) outside the internal oblique angle contact surface (6), the cross-section of the annular groove (13) is inverted L-shaped, a sealing ring (11) is installed in the annular groove (13), and the external oblique angle contact surface (5) and the sealing ring (11) are in sealing contact, characterized in that, The upper end of the sealing ring (11) is provided with an upper flange (16), and the inner edge surface of the sealing ring (11) away from the internal thread (2) is provided with a side flange (17). The groove wall of the ring groove (13) is provided with an upper groove (14) and a side groove (15). The upper groove (14) corresponds to the upper flange (16), and the side groove (15) corresponds to the side flange (17). The upper flange (16) is engaged in the upper groove (14), and the side flange (17) is engaged in the side groove (15).

2. The gas-tight structure for oil casing according to claim 1, characterized in that, The connecting section of the pipe fitting (10) is machined with an outer sealing surface and an outer oblique angle contact surface (5), and the connecting section of the coupling (9) is machined with an inner sealing surface and an inner oblique angle contact surface (6). The outer sealing surface and the inner sealing surface are respectively provided. The outer sealing surface includes an outer conical surface (7) and an outer sealing cylindrical surface (3) connected to each other. The inner sealing surface includes an inner conical surface (8) and an inner sealing cylindrical surface (4) connected to each other. The inner conical surface (8) and the outer conical surface (7) are interference fit, and the inner sealing cylindrical surface (4) and the outer sealing cylindrical surface (3) are interference fit.

3. The gas-tight structure for oil casing according to claim 2, characterized in that, The outer sealing cylindrical surface (3) is in sealing contact with the sealing ring (11).

4. The gas-tight structure for oil casing according to claim 1, characterized in that, The upper wall of the annular groove (13) is an upper conical surface (18), the outer edge of the upper conical surface (18) is inclined towards the internal thread (2), the upper end face of the sealing ring (11) is an upper fitting conical surface (20), the upper fitting conical surface (20) fits with the upper conical surface (18), and the upper groove (14) is opened on the upper conical surface (18).

5. The gas-tight structure for oil casing according to claim 2, characterized in that, The inner edge of the sealing ring (11) near the internal thread (2) is a sealing cone (22). The end of the sealing cone (22) away from the internal thread (2) is inclined toward the center of the coupling (9). The diameter of the end of the sealing cone (22) opposite to the inner sealing cylinder (4) is equal.

6. The gas-tight structure for oil casing according to claim 1, characterized in that, The inner edge of the sealing ring (11) away from the internal thread (2) is a side-fitting conical surface (21), the groove wall of the ring groove (13) near the axis of the coupling (9) is a side conical surface (19), the end of the side conical surface (19) near the internal thread (2) is inclined to the outside of the coupling (9), the side-fitting conical surface (21) fits with the side conical surface (19), and the side groove (15) is opened on the side conical surface (19).

7. The gas-tight structure for oil casing according to claim 1, characterized in that, The sealing ring (11) is provided with a rib ring (12) with an inverted L-shaped cross section. The rib ring (12) is made of elastic material. One end of the rib ring (12) extends into the upper flange (16), and the other end of the rib ring (12) extends into the side flange (17).

8. The gas-tight structure for oil casing according to claim 7, characterized in that, The reinforcing ring (12) is made of PVC material.

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