Oil casing thread joint

Abstract

This invention provides a threaded connector for an oil casing pipe. The threaded connector includes: an external threaded connector; and an internal threaded connector, threadedly connected to the external threaded connector. Along the axial direction of the threaded connector, an external sealing portion, a threaded portion, and an internal sealing portion and a shoulder portion are sequentially formed between the external threaded connector and the internal threaded connector from the outside to the inside. The external sealing portion includes a first external sealing surface disposed on the external threaded connector and a second external sealing surface disposed on the internal threaded connector, with the first external sealing surface and the second external sealing surface sealingly mating. The distance from the midpoint of the second external sealing surface to the pipe end face of the internal threaded connector is L20, and the nose length of the internal threaded connector is L21, wherein L20 and L21 satisfy the following relationship: 0.15 ≤ L20 / L21 ≤ 0.75. In the technical solution of this invention, the threaded connector for an oil casing pipe can achieve independent internal and external double sealing, resulting in more reliable sealing.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of petroleum pipe engineering, in particular to an oil casing thread joint. BACKGROUND

[0002] With the increasingly complex development environment of oil and gas fields, the sealing performance of the oil casing thread joint is required to be more stringent, that is, it can still maintain excellent sealing robustness and excellent compression performance under various complex and harsh working conditions such as tension, compression, internal pressure, external pressure, bending and occasional external factors.

[0003] At present, most oil casing thread joints only set an inner sealing structure for one-time sealing, and the sealing effect is unreliable. SUMMARY

[0004] The main purpose of the present application is to provide an oil casing thread joint which can realize independent inner and outer double sealing and is more reliable in sealing.

[0005] In order to achieve the above purpose, the present application provides an oil casing thread joint, comprising: an outer thread joint; an inner thread joint threadedly connected with the outer thread joint; along the axial direction of the oil casing thread joint, an outer sealing part, a threaded part and an inner sealing and shoulder part are sequentially formed between the outer thread joint and the inner thread joint from the outer side to the inner side; wherein the outer sealing part comprises a first outer sealing surface arranged on the outer thread joint and a second outer sealing surface arranged on the inner thread joint, and the first outer sealing surface is sealingly matched with the second outer sealing surface; the distance from the midpoint of the second outer sealing surface to the pipe end surface of the inner thread joint is L20, and the length of the nose end of the inner thread joint is L21, wherein L20 and L21 satisfy the following relationship: 0.15≤L20 / L21≤0.75.

[0006] Further, the first outer sealing surface has an included angle a1 with the axial direction of the oil casing thread joint, the included angle a1 satisfies the following relationship: 3.50°≤a1≤9.90°; the second outer sealing surface has an included angle b1 with the axial direction of the oil casing thread joint, the included angle b1 satisfies the following relationship: 3.50°≤b1≤9.90°; and the included angle a1 and the included angle b1 both satisfy the following relationship: 0°≤a1-b1≤1.5°.

[0007] Further, along the axial direction of the oil casing thread joint, the length of the second outer sealing surface is L22, and L22 satisfies the following relationship: 2mm≤L22≤5mm.

[0008] Further, the inner thread joint is further provided with a first connecting surface, one end of the first connecting surface is connected with the pipe end surface, and the other end of the first connecting surface is connected with the second outer sealing surface; the first connecting surface comprises at least one of a conical surface, a cylindrical surface and an arc surface.

[0009] Further, the first outer sealing surface and the outer peripheral surface of the body of the male threaded joint have a second connecting surface therebetween; the second connecting surface is not on the same circumferential surface as the first outer sealing surface; or the second connecting surface is on the same circumferential surface as the first outer sealing surface.

[0010] Further, the threaded portion comprises: a first thread arranged on the outer wall surface of the male threaded joint; a second thread arranged on the inner wall surface of the female threaded joint; the first thread and the second thread are threadedly engaged to threadedly connect the male threaded joint and the female threaded joint; wherein, when the first thread and the second thread are threadedly engaged, a first thread tooth of the first thread and a second thread tooth of the second thread are engaged, and an adjacent first thread tooth and second thread tooth have a thread side gap d, d satisfies the following relationship: 0.02mm≤d≤0.15mm.

[0011] Further, the inner sealing and shoulder portion comprises a first inner sealing surface arranged on the male threaded joint and a second inner sealing surface arranged on the female threaded joint, the first inner sealing surface and the second inner sealing surface are sealingly engaged; a nose length of the male threaded joint is L10, a distance from a midpoint of the second inner sealing surface to a first butt shoulder surface of the female threaded joint is L23, wherein L10 and L23 satisfy the following relationship: 0.25≤L23 / L10≤0.9.

[0012] Further, the first inner sealing surface and the axial direction of the oil casing threaded joint have an included angle α2, the included angle α2 satisfies the following relationship: 3.50°≤α2≤9.90°; the second inner sealing surface and the axial direction of the oil casing threaded joint have an included angle β2, the included angle β2 satisfies the following relationship: 3.50°≤β2≤9.90°; and the included angle α2 and the included angle β2 both satisfy the following relationship: 0°≤β2-α2≤1.5°.

[0013] Further, along the axial direction of the oil casing threaded joint, a length of the second inner sealing surface is L24, L24 satisfies the following relationship: 2mm≤L24≤5mm.

[0014] Further, the female threaded joint is further provided with a second connecting surface, one end of the second connecting surface is connected with the second inner sealing surface, and the other end of the second connecting surface is connected with the first butt shoulder surface; the second connecting surface comprises at least one of a tapered surface, a cylindrical surface and an arc surface.

[0015] Further, the inner seal and shoulder further comprises a first shoulder surface arranged on the end surface of the external threaded joint and connected with the first inner sealing surface, the first shoulder surface is in interference fit with the first pair of shoulder surfaces; wherein the first shoulder surface has an included angle a3 with the vertical direction, the included angle a3 satisfies the following relationship: 0°≤a3≤15°; the first pair of shoulder surfaces has an included angle b3 with the vertical direction, the included angle b3 satisfies the following relationship: 0°≤b3≤15°; and the included angle a3 and the included angle b3 both satisfy the following relationship: 0°≤b3-a3≤1°.

[0016] By the technical scheme of the present application, the external threaded joint and the internal threaded joint are in threaded connection. Along the axial direction of the oil casing threaded joint, the external threaded joint and the internal threaded joint are sequentially provided with an outer seal portion, a threaded portion and an inner seal and shoulder portion from the outer side to the inner side. The first outer sealing surface of the external threaded joint and the second outer sealing surface of the internal threaded joint are in radial interference fit, thereby generating an outer sealing effect; the first inner sealing surface of the external threaded joint and the second inner sealing surface of the internal threaded joint are in radial interference fit, thereby generating an inner sealing effect. In the embodiment of the present application, the independent inner and outer double sealing can be realized by the outer seal portion and the inner seal and shoulder portion, and the sealing is more reliable. BRIEF DESCRIPTION OF DRAWINGS

[0017] The accompanying drawings, which form a part of the present application, are used to provide further understanding of the present application, and serve as an aid in explaining the present application. The schematic embodiments of the present application and their descriptions are used to explain the present application, and do not constitute an improper limitation on the present application. In the drawings:

[0018] Figure 1 A structure schematic view of an embodiment of the oil casing threaded joint according to the present application is shown;

[0019] Figure 2 A structure schematic view of the external threaded joint of the oil casing threaded joint of Figure 1 is shown;

[0020] Figure 3 A structure schematic view of the internal threaded joint of the oil casing threaded joint of Figure 1 is shown;

[0021] Figure 4 An enlarged view of a1 of the external threaded joint of Figure 2 is shown;

[0022] Figure 5 An enlarged view of a2 of the internal threaded joint of Figure 3 is shown;

[0023] Figure 6 An enlarged view of b of the oil casing threaded joint of Figure 1 is shown;

[0024] Figure 7 An enlarged view ofFigure 1 Enlarged view of c of the oil casing thread joint of the present application;

[0025] Figure 8 An enlarged view of c1 of the pin joint of the present application is shown; Figure 2

[0026] Figure 9 An enlarged view of c2 of the box joint of the present application is shown; Figure 3

[0027] Figure 10 A graph showing the relationship between the quantitative index of the sealing performance based on finite element analysis and L20 / L21 of the oil casing thread joint of the present application; and

[0028] Figure 11 A graph showing the relationship between the quantitative index of the sealing performance based on finite element analysis and L23 / L10 of the oil casing thread joint of the present application.

[0029] In the above drawings, the following reference signs are used:

[0030] 1, pin joint; 10, outer peripheral surface of the body; 11, first outer sealing surface; 12, first thread; 13, first inner sealing surface; 14, first shoulder surface; 15, inclined surface; 2, box joint; 20, pipe end surface; 21, first connecting surface; 22, second outer sealing surface; 23, second thread; 24, second inner sealing surface; 25, second connecting surface; 26, first stabbing shoulder surface. DETAILED DESCRIPTION

[0031] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict. The present application will be described in detail below with reference to the drawings and in combination with the embodiments.

[0032] It should be noted that, unless otherwise specified, all the technical and scientific terms used in the present application have the same meaning as that generally understood by the ordinary skilled in the art to which the present application belongs.

[0033] In the present application, unless otherwise specified, the orientation words such as "upper", "lower", "top", "bottom" are generally directed to the directions shown in the drawings, or are directed to the vertical, perpendicular or gravity directions of the components themselves; similarly, for the convenience of understanding and description, "inner" and "outer" refer to the inner and outer relative to the contour of the components themselves, but the above orientation words are not used to limit the present application.

[0034] With the increasingly complex development environment of oil and gas fields, the sealing performance of oil casing thread joints is required to be more stringent, i.e. to maintain excellent sealing robustness and excellent compression performance under various complex and harsh working conditions such as tension, compression, internal pressure, external pressure, bending and other occasional external factors.​​

[0035] Standard API (American Petroleum Institute) threaded oil casing has design defects, which result in low connection strength of threaded joints, poor resistance to combined load, and no gas sealing performance, and thus cannot be used in harsh well conditions, and is mainly used in shallow wells, low pressure wells and other well conditions with low requirements.

[0036] A Chinese patent (publication number CN 203925329U) discloses a utility model patent named "gas sealing oil casing joint", the threaded joint of which has an involute structure, the tooth top and tooth bottom are parallel to the threaded generatrix, the outer threaded joint end is designed with a first positioning shoulder and a first sealing surface, the inner threaded joint is designed with a corresponding second positioning shoulder and a second sealing surface, and the first sealing surface and the second sealing surface are conical surfaces with an inclination angle β, wherein 0.1≤tanβ≤1.8. The sealing structure of this relatively traditional structure is close to the shoulder, and the sealing performance is seriously affected by the stress state of the positioning shoulder, and the stability of the sealing performance is not high.

[0037] A Chinese patent (publication number CN 2575286Y) discloses a utility model patent named "oil and casing threaded joint", the threaded joint of which has an improved involute structure, and the sealing structure adopts a structure in which the outer sealing surface is a cylindrical surface and the inner sealing surface is a spherical surface. The production, processing and detection of this sealing structure are difficult, and the sealing structure is prone to accidental damage.

[0038] A Chinese patent (publication number CN 100390454C) discloses an invention patent named "improved threaded pipe connection comprising at least one threaded element having an end lip", the threaded joint of which is designed with an "accessory" between the sealing surface and the shoulder, and the "accessory" is not on the same circumferential surface as the sealing surface. The sealing structure is complex to process, an additional "accessory" structure needs to be processed, and the sealing surface angle is at least 10 degrees. A too large sealing surface angle will cause the thickness of the shoulder to be too thin, and will affect the compression performance to some extent.

[0039] A Chinese patent (publication number CN 102313085A) discloses an invention patent named "threaded joint for pipes", the threaded joint of which adopts a sealing structure in which three arc surfaces are connected. The production, processing and detection of this sealing structure are difficult, and the sealing structure is prone to damage and sticking.

[0040] Most current oil casing threaded joints only have an inner sealing structure for one-time sealing, and the sealing effect is unreliable.

[0041] And, the sealing contact length being too long will result in sealing contact pressure being reduced, thereby affecting sealing performance; the sealing contact length being too short will result in sealing contact pressure being too high, which may cause the sealing surface to be stuck; and the distance between the sealing contact position and the pipe end affects the sealing contact state and compression performance of the oil casing thread joint.

[0042] To solve the above problems, the present application and the embodiments thereof provide an oil casing thread joint.

[0043] As shown in Figures 1 to 9 the embodiments of the present application, the oil casing thread joint comprises an external thread joint 1 and an internal thread joint 2, and the external thread joint 1 and the internal thread joint 2 are screwed together. The external thread joint 1 is machined on the outer surface of the pipe end, and the main structures from the steel pipe body to the pipe end are a first outer sealing surface 11, a first thread 12, a first inner sealing surface 13, a first shoulder surface 14 and an inclined surface 15 in sequence. The internal thread joint 2 is machined on the inner surface of the pipe end, and the main structures from the pipe end to the steel pipe body are a first connecting surface 21, a second outer sealing surface 22, a second thread 23, a second inner sealing surface 24, a second connecting surface 25 and a first stabbing shoulder surface 26 in sequence.

[0044] As shown in Figures 1 to 5 the embodiments of the present application, the oil casing thread joint comprises an external thread joint 1 and an internal thread joint 2, and the internal thread joint 2 is threadedly connected with the external thread joint 1; along the axial direction of the oil casing thread joint, the external thread joint 1 and the internal thread joint 2 are sequentially formed with an outer sealing portion a, a thread portion b and an inner sealing and shoulder portion c from the outer side to the inner side; wherein the outer sealing portion a comprises a first outer sealing surface 11 arranged on the external thread joint 1 and a second outer sealing surface 22 arranged on the internal thread joint 2, and the first outer sealing surface 11 is sealingly matched with the second outer sealing surface 22; the distance from the midpoint of the second outer sealing surface 22 to the pipe end surface 20 of the internal thread joint 2 is L20, and the nose length of the internal thread joint 2 is L21, wherein L20 and L21 satisfy the following relationship: 0.15≤L20 / L21≤0.75.

[0045] In the embodiments of the present application, the oil casing thread joint comprises an external thread joint 1 and an internal thread joint 2. The external thread joint 1 and the internal thread joint 2 are threadedly connected. Along the axial direction of the oil casing thread joint, the external thread joint 1 and the internal thread joint 2 are sequentially formed with an outer sealing portion a, a thread portion b and an inner sealing and shoulder portion c from the outer side to the inner side. The first outer sealing surface 11 of the external thread joint 1 and the second outer sealing surface 22 of the internal thread joint 2 are in radial interference fit, thereby generating a sealing effect to realize outer sealing; the inner sealing and shoulder portion can realize inner sealing.

[0046] In the embodiments of the present invention, independent internal and external double sealing can be achieved by the outer sealing part a (outer sealing structure) and the inner sealing and shoulder part c (inner sealing structure), making the sealing more reliable.

[0047] In embodiments of the present invention, the distance L20 from the midpoint of the second outer sealing surface 22 to the pipe end face 20 of the internal threaded connector 2 and the nose length L21 of the internal threaded connector 2 satisfy a set relationship. If the value of L20 / L21 is too large or too small, the sealing contact state will deteriorate due to the influence of the free pipe end expansion or external pressure, thus affecting the sealing performance.

[0048] The smaller the L20 / L21 value, the closer the second outer sealing surface 22 is to the pipe end, which will cause the second outer sealing surface 22 to be affected by the expansion of the free pipe end, thus affecting the sealing performance. The larger the L20 / L21 value, the more the contact state between the first outer sealing surface 11 of the external threaded joint 1 and the second outer sealing surface 22 of the internal threaded joint 2 tends to separate under external pressure, thus affecting the sealing performance.

[0049] After finite element analysis, such as Figure 10 As shown, P represents the sealing contact pressure, and x represents the sealing contact length. Since the sealing performance is determined by both the sealing contact pressure and the sealing contact length, the quantitative index of sealing performance is expressed by integrating the sealing contact pressure P over the sealing contact length x. x Pdx shows that when 0.15≤L20 / L21≤0.75, the oil casing threaded joint has good sealing performance and excellent sealing quantification index. Therefore, in the embodiments of the present invention, the distance L20 and the nose length L21 satisfy the following relationship: 0.15≤L20 / L21≤0.75.

[0050] Preferably, the distance L20 and the nasal tip length L21 satisfy the following relationship: 0.40≤L20 / L21≤0.50.

[0051] It should be noted that, in the embodiments of the present invention, the midpoint of the second outer sealing surface 22 refers to the exact midpoint of the second outer sealing surface 22, which is equidistant from the two endpoints of the second outer sealing surface 22.

[0052] In the embodiments of the present invention, the oil casing threaded joint is an oil casing threaded joint with excellent external pressure sealing performance, internal pressure sealing performance and compression performance. The threaded joint still has good structural integrity and sealing integrity under various complex and harsh load conditions, and at the same time has excellent sealing robustness. It can be applied to oil and gas wells with complex geological conditions such as high temperature, high pressure and ultra-deep.

[0053] like Figure 4 and Figure 5As shown, in the embodiment of the present application, the first outer sealing surface 11 has an included angle a1 with the axial direction of the oil casing threaded joint, the included angle a1 satisfies the following relationship: 3.50°≤a1≤9.90°; the second outer sealing surface 22 has an included angle b1 with the axial direction of the oil casing threaded joint, the included angle b1 satisfies the following relationship: 3.50°≤b1≤9.90°; and the included angle a1 and the included angle b1 both satisfy the following relationship: 0°≤a1-b1≤1.5°.

[0054] In the embodiment of the present application, the included angle a1 corresponding to the first outer sealing surface 11 of the external threaded joint 1 satisfies the angle range: 3.50°≤a1≤9.90°, the included angle b1 corresponding to the second outer sealing surface 22 of the internal threaded joint 2 satisfies the angle range: 3.50°≤b1≤9.90°, and the included angle a1 and the included angle b1 both satisfy the following relationship: 0°≤a1-b1≤1.5°. In this way, the reduction of the sealing contact pressure on the side close to the pipe end due to the pipe end necking of the internal threaded joint and the external pressure can be compensated, so that the sealing contact pressure is uniformly distributed, and a stable sealing effect is achieved. Through the above setting, the oil casing threaded joint has excellent sealing distribution state and good sealing surface anti-sticking performance.

[0055] Preferably, the included angle a1 and the included angle b1 both satisfy the following relationship: 0.2°≤a1-b1≤0.5°.

[0056] As shown in the drawings, Figure 5 In the embodiment of the present application, along the axial direction of the oil casing threaded joint, the length of the second outer sealing surface 22 is L22, and L22 satisfies the following relationship: 2mm≤L22≤5mm.

[0057] In the embodiment of the present application, the length L22 of the second outer sealing surface 22 of the internal threaded joint 2 satisfies the length range: 2mm≤L22≤5mm. In this way, a comprehensive optimal sealing contact pressure and sealing contact length can be achieved.

[0058] As shown in the drawings, Figure 5 In the embodiment of the present application, the internal threaded joint 2 is further provided with a first connecting surface 21, one end of the first connecting surface 21 is connected with the pipe end surface 20, and the other end of the first connecting surface 21 is connected with the second outer sealing surface 22; the first connecting surface 21 includes at least one of a conical surface, a cylindrical surface and an arc surface.

[0059] In the embodiment of the present application, the circumferential surface between the second outer sealing surface 22 and the pipe end surface 20 of the pin 2 forms a first connecting surface 21, the first connecting surface 21 is not on the same circumferential surface with the second outer sealing surface 22, and the first connecting surface 21 can be composed of various line segments and / or arc surfaces. In this way, the rigidity of the first connecting surface 21 is reduced, the rigidity of the second outer sealing surface 22 is increased, the rigidity of the outer sealing part is improved, the outer sealing contact can maintain stable close contact, and thus the oil casing thread joint has excellent outer sealing performance.

[0060] In the embodiment of the present application, the distance L20 from the midpoint of the second outer sealing surface 22 of the pin 2 to the pipe end surface 20 of the pin 2 satisfies a certain relationship with the nose length L21 of the pin 2, and the circumferential surface between the second outer sealing surface 22 and the pipe end surface 20 (i.e. the first connecting surface 21) is not on the same circumferential surface with the second outer sealing surface 22, and the first connecting surface 21 can be composed of various line segments and / or arc surfaces. In this way, the rigidity of the outer sealing part is improved, which is beneficial to improve the sealing performance of the oil casing thread joint under external pressure.

[0061] As shown in Figure 4 , in the embodiment of the present application, the first outer sealing surface 11 and the body outer peripheral surface 10 of the box 1 have a second connecting surface; the second connecting surface between the first outer sealing surface 11 and the body outer peripheral surface 10 of the box 1 can be not on the same circumferential surface with the first outer sealing surface 11, or can be on the same circumferential surface with the first outer sealing surface 11 (as shown by the dashed line in Figure 4 ).

[0062] It should be noted that the second connecting surface includes at least one of a conical surface and a cylindrical surface, and an arc surface. Of course, the second connecting surface can only include at least one of a conical surface and a cylindrical surface.

[0063] As shown in Figure 6 , in the embodiment of the present application, the threaded part b includes a first thread 12 arranged on the outer wall surface of the box 1 (as shown at b1 in Figure 2 ) and a second thread 23 arranged on the inner wall surface of the pin 2 (as shown at b2 in Figure 3 ); the first thread 12 and the second thread 23 are threadedly connected to threadedly connect the box 1 and the pin 2; wherein when the first thread 12 and the second thread 23 are threadedly connected, the first thread teeth of the first thread 12 and the second thread teeth of the second thread 23 are engaged, and the adjacent first thread teeth and second thread teeth have a thread side gap d, and d satisfies the following relationship: 0.02mm≤d≤0.15mm.

[0064] In the embodiment of the present application, the tooth side gap d between the first thread teeth of the first thread 12 on the pin 1 and the second thread teeth of the second thread 23 on the box 2 meets a given range. If d is too small, the thread teeth are prone to damage and sticking during operation; if d is too large, the compression performance of the oil casing thread joint is affected; the reasonable range of the tooth side gap d is 0.02mm≤d≤0.15mm, so that the oil casing thread joint has good make-up operation performance and compression performance at the same time.

[0065] As shown in Figure 8 and Figure 9 In the embodiment of the present application, the internal seal and shoulder portion c includes a first internal seal surface 13 arranged on the pin 1 and a second internal seal surface 24 arranged on the box 2, and the first internal seal surface 13 and the second internal seal surface 24 are in sealing cooperation; the nose length of the pin 1 is L10, and the distance from the midpoint of the second internal seal surface 24 to the first butt shoulder surface 26 of the box 2 is L23, wherein L10 and L23 meet the following relationship: 0.25≤L23 / L10≤0.9.

[0066] In the embodiment of the present application, the first internal seal surface 13 of the pin 1 and the second internal seal surface 24 of the box 2 are in radial interference fit, thereby generating a sealing effect.

[0067] In the embodiment of the present application, the distance L23 from the midpoint of the second internal seal surface 24 to the first butt shoulder surface 26 of the box 2 and the nose length L10 of the pin 1 meet a given relationship.

[0068] The smaller the value of L23 / L10, the closer the internal seal contact area is to the shoulder, which will cause the internal seal contact state to be easily affected by the adjacent force shoulder (the interference fit between the first shoulder surface 14 and the first butt shoulder surface 26), thereby affecting the sealing performance; at the same time, the smaller the value of L23 / L10, the closer the internal seal contact area is to the shoulder contact position, and the shorter the compression deformation energy storage length between the internal seal contact area and the shoulder contact position when the oil casing thread joint is subjected to compression, thereby affecting the compression performance. At the same time, the smaller the value of L23 / L10, the closer the internal seal contact area is to the pipe end, and the more the first internal seal surface 13 of the pin 1 tends to shrink under external pressure, causing the contact state between the first internal seal surface 13 of the pin 1 and the second internal seal surface 24 of the box 2 to tend to separate, thereby affecting the sealing performance. The larger the value of L23 / L10, the more the internal seal surface of the box 2 tends to expand under internal pressure, and the more the contact state between the first internal seal surface 13 of the pin 1 and the second internal seal surface 24 of the box 2 tends to separate, thereby affecting the sealing performance.

[0069] Through finite element analysis, as shown inFigure 11 As shown, P represents the sealing contact pressure, and x represents the sealing contact length. Since the sealing performance is determined by the sealing contact pressure and the sealing contact length, the sealing performance is quantified by integrating the sealing contact pressure P with respect to the sealing contact length x. x Pdx, it can be seen that when 0.25≤L23 / L10≤0.9, the sealing quantification index is better. Therefore, the reasonable range of L23 / L10 is 0.25≤L23 / L10≤0.9. In this way, the oil casing thread joint has good sealing performance and compression performance at the same time.

[0070] Preferably, 0.65≤L23 / L10≤0.85.

[0071] As shown in Figure 8 and Figure 9 In the embodiment of the present application, the first inner sealing surface 13 has an included angle α2 with the axial direction of the oil casing thread joint, the included angle α2 satisfies the following relationship: 3.50°≤α2≤9.90°; the second inner sealing surface 24 has an included angle β2 with the axial direction of the oil casing thread joint, the included angle β2 satisfies the following relationship: 3.50°≤β2≤9.90°; and the included angle α2 and the included angle β2 both satisfy the following relationship: 0°≤β2-α2≤1.5°.

[0072] In the embodiment of the present application, the included angle α2 corresponding to the first inner sealing surface 13 of the external thread joint 1 satisfies the angle range: 3.50°≤α2≤9.90°, the included angle β2 corresponding to the second inner sealing surface 24 of the internal thread joint 2 satisfies the angle range: 3.50°≤β2≤9.90°, and the included angle α2 and the included angle β2 both satisfy the following relationship: 0°≤β2-α2≤1.5°. In this way, the sealing contact pressure near the pipe end side caused by the pipe end necking of the external thread joint and the internal pressure can be compensated, so that the sealing contact pressure is uniformly distributed, and stable sealing effect is achieved. Through the above setting, the oil casing thread joint has excellent sealing distribution state and good sealing surface anti-sticking performance.

[0073] Preferably, 0.2°≤β2-α2≤0.5°.

[0074] As shown in Figure 9 In the embodiment of the present application, the length of the second inner sealing surface 24 along the axial direction of the oil casing thread joint is L24, and L24 satisfies the following relationship: 2mm≤L24≤5mm.

[0075] In the embodiment of the present application, the length L24 of the second inner sealing surface 24 of the internal thread joint 2 is in the range of 2mm≤L24≤5mm. In this way, the sealing contact pressure and the sealing contact length can be comprehensively optimized.

[0076] As Figure 9 shown, in the embodiment of the present application, the internal thread joint 2 is further provided with a second connecting surface 25, one end of the second connecting surface 25 is connected with the second inner sealing surface 24, and the other end of the second connecting surface 25 is connected with the first abutting shoulder surface 26; the second connecting surface 25 comprises at least one of a tapered surface, a cylindrical surface and an arc surface.

[0077] In the embodiment of the present application, the circumferential surface between the second inner sealing surface 24 and the first abutting shoulder surface 26 forms the second connecting surface 25, the second connecting surface 25 is not on the same circumferential surface with the second inner sealing surface 24, and the second connecting surface 25 can be composed of various line segments and / or arc surfaces, etc. This arrangement improves the rigidity of the inner sealing part (the first inner sealing surface 13 and the second inner sealing surface 24 are in radial interference fit), and the inner sealing contact pair can maintain stable and close contact, thereby making the oil casing thread joint have excellent inner sealing performance.

[0078] As Figure 7 and Figure 9 shown, in the embodiment of the present application, the second connecting surface 25 of the internal thread joint 2 and the first inner sealing surface 13 of the external thread joint 1 can be non-contact or partially contact (as shown by the dashed line in Figure 7 ).

[0079] In the embodiment of the present application, the distance L23 between the midpoint of the second inner sealing surface 24 and the first abutting shoulder surface 26 of the internal thread joint 2 and the nose length L10 of the external thread joint 1 satisfy a set relationship, and the circumferential surface between the second inner sealing surface 24 and the first abutting shoulder surface 26 (i.e. the second connecting surface 25) is not on the same circumferential surface with the second inner sealing surface 24, and the second connecting surface 25 can be composed of various line segments and / or arc surfaces, etc. This arrangement improves the rigidity of the inner sealing part, and is beneficial to improve the sealing performance of the oil casing thread joint under internal pressure.

[0080] As Figure 8 and Figure 9 shown, in the embodiment of the present application, the inner sealing and shoulder part c further comprises a first shoulder surface 14 arranged on the end face of the external thread joint 1 and connected with the first inner sealing surface 13, and the first shoulder surface 14 is in interference fit with the first abutting shoulder surface 26; wherein the first shoulder surface 14 has an included angle α3 with the vertical direction, the included angle α3 satisfies the following relationship: 0°≤α3≤15°; the first abutting shoulder surface 26 has an included angle β3 with the vertical direction, the included angle β3 satisfies the following relationship: 0°≤β3≤15°; and the included angle α3 and the included angle β3 both satisfy the following relationship: 0°≤β3-α3≤1°.

[0081] In the embodiment of the present application, the first shoulder surface 14 and the first abutting shoulder surface 26 are in interference contact with each other, which plays a role of screwing positioning and compression resistance.

[0082] In the embodiments of the present invention, the included angle α3 corresponding to the first shoulder surface 14 of the external threaded connector 1 satisfies the angle range of 0°≤α3≤15°, and the included angle β3 corresponding to the first paired shoulder surface 26 of the internal threaded connector 2 satisfies the angle range of 0°≤β3≤15°, and both included angles α3 and β3 satisfy the following relationship: 0°≤β3-α3≤1°. This setting compensates for the reduction in interference fit near the inner side of the shoulder caused by the necking of the pipe end of the external threaded connector, making the shoulder surface more uniformly stressed after interference contact between the shoulders, thereby giving the oil sleeve threaded connector good compression performance, and also benefiting good contact between the first inner sealing surface 13 and the second inner sealing surface 24.

[0083] Preferably, 0.2°≤β3-α3≤0.8°.

[0084] like Figure 8 As shown, in an embodiment of the present invention, the external threaded connector 1 has an inclined surface 15, which is disposed on a portion of the inner wall surface of the external threaded connector 1. Along the axial direction of the oil casing threaded connector, the inclined surface 15 gradually moves away from the axis of the oil casing threaded connector and connects to the first shoulder surface 14.

[0085] In embodiments of the present invention, the inclined surface 15 can be a single conical surface or a composite surface composed of a cylindrical surface and a conical surface. By setting and processing the inclined surface 15, the uneven circumferential wall thickness of the rolled steel pipe can be prevented from causing an uneven and unstable contact state to the inner sealing contact pair (the first inner sealing surface 13 and the second inner sealing surface 24). At the same time, the external threaded joint 1 and the internal threaded joint 2 are kept flush at the inner hole where the shoulder contacts, preventing turbulence.

[0086] like Figure 8 Figure 8 As shown, in an embodiment of the present invention, the inclined surface 15 of the external threaded connector 1 and the axial direction of the oil sleeve threaded connector have an included angle α4, and the included angle α4 satisfies the following relationship: 6°≤α4≤20°.

[0087] In embodiments of the present invention, the oil-jacket threaded joint has the following advantages:

[0088] 1. The first outer sealing surface 11 of the external threaded connector 1 and the second outer sealing surface 22 of the internal threaded connector 2 are radially interference-fitted, thereby producing a sealing effect and achieving an external seal; the first inner sealing surface 13 of the external threaded connector 1 and the second inner sealing surface 24 of the internal threaded connector 2 are radially interference-fitted, thereby producing a sealing effect and achieving an internal seal. The use of both internal and external sealing structures achieves independent internal and external double sealing, resulting in more reliable sealing.

[0089] 2. Based on finite element analysis, the optimized sealing surface structure parameters are adopted, and the sealing integrity and sealing robustness of the threaded joint are greatly improved;

[0090] 3. The setting of the outer sealing surface angle relationship, the inner sealing surface angle relationship and the shoulder surface angle relationship compensates the influence of uneven pressure at the contact position, and realizes the stable sealing effect and good compression performance.

[0091] In the embodiment of the present application, the oil casing threaded joint is a high-performance oil casing threaded joint, mainly used in well conditions with high requirements for external pressure gas sealing performance, internal pressure gas sealing performance and compression performance. The oil casing threaded joint is a threaded joint mainly used in oil casing in the petroleum industry, and is a tubular connecting element in the field of oil pipe technology.

[0092] The technical solution of the present application is applied:

[0093] Embodiment one

[0094] In the embodiment one of the present application, the pipe body adopts 244.48x11.99mm specification casing, the steel grade is P110, the coupling outer diameter is regulated according to API standard, and the material performance meets the requirements of API standard.

[0095] The threaded joint geometric parameters are: L20 / L21=0.45, L22=2.50mm, α1=7.1°, β1=6.7°, d=0.4mm, L23 / L10=0.75, L24=3.5mm, α3=8°, β3=8.5°, α4=10°.

[0096] The connection strength of the casing threaded joint reaches 6641kN, the compression resistance reaches 6641kN, the internal pressure sealing performance reaches more than 65Mpa, the external pressure performance reaches more than 37Mpa, the bending resistance reaches more than 20° / 30m, and the requirement of not sticking for three times of make-up and break-out is met. The casing threaded joint has excellent internal pressure sealing performance, external pressure sealing performance and compression performance.

[0097] Embodiment two

[0098] In the embodiment two of the present application, the pipe body adopts 88.9x9.52mm specification tubing, the steel grade is P110, the coupling outer diameter is regulated according to API standard, and the material performance meets the requirements of API standard.

[0099] The outer threaded joint geometric parameters are: L20 / L21=0.50, L22=2.40mm, α1=7.1°, β1=6.7°, d=0.3mm, L23 / L10=0.80, L24=3.5mm, α3=8°, β3=8.5°, α4=10°.

[0100] The connecting strength of the casing thread joint reaches 1800kN, the compression resistance reaches 1800kN, the internal pressure sealing performance reaches above 142Mpa, the external pressure sealing performance reaches above 145Mpa, the bending resistance reaches above 45° / 30m, and the requirement of 10 times of make-up and unmake-up without sticking is met. The tubing thread joint has excellent internal pressure sealing performance, external pressure sealing performance and compression performance.

[0101] From the above description, it can be seen that the above-mentioned embodiments of the present application achieve the following technical effects: the external thread joint and the internal thread joint are threadedly connected. Along the axial direction of the oil casing thread joint, the external thread joint and the internal thread joint are sequentially formed with an external sealing portion, a threaded portion and an internal sealing and shoulder portion from the outside to the inside. The first external sealing surface of the external thread joint and the second external sealing surface of the internal thread joint are in radial interference fit, thereby generating a sealing effect to realize external sealing; the first internal sealing surface of the external thread joint and the second internal sealing surface of the internal thread joint are in radial interference fit, thereby generating a sealing effect to realize internal sealing. In the embodiments of the present application, independent internal and external double sealing can be realized through the external sealing portion and the internal sealing and shoulder portion, and the sealing is more reliable.

[0102] Obviously, the above-mentioned embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor should belong to the scope of protection of the present application.

[0103] It should be noted that the terms used herein are only intended to describe specific embodiments, and are not intended to limit the exemplary embodiments according to the present application. As used herein, the singular form is intended to include the plural form, unless the context clearly indicates otherwise, and it should be understood that when the terms "comprise" and / or "include" are used in the specification, there is a reference to the presence of a feature, step, work, device, component and / or combinations thereof.

[0104] It should be noted that the terms "first", "second" and the like in the specification and claims of the present application and the above-described drawings are used to distinguish similar objects, and do not necessarily indicate a specific order or sequence. It should be understood that the data used in this way can be interchanged under appropriate circumstances, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein.

[0105] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A tubing-casing threaded joint characterized by, The oil jacket pipe threaded joint comprises: an external threaded joint (1); an internal threaded joint (2) threadedly connected with the external threaded joint (1); along the axial direction of the oil jacket pipe threaded joint, the external threaded joint (1) and the internal threaded joint (2) are sequentially provided with an external sealing part (a), a threaded part (b) and an internal sealing and shoulder part (c) from the outside to the inside along the axial direction of the oil jacket pipe threaded joint; wherein the external sealing part (a) comprises a first external sealing surface (11) arranged on the external threaded joint (1) and a second external sealing surface (22) arranged on the internal threaded joint (2), the first external sealing surface (11) is sealingly matched with the second external sealing surface (22), and no shoulder surface is arranged at the external sealing part (a); the distance from the midpoint of the second external sealing surface (22) to the pipe end surface (20) of the internal threaded joint (2) is L20, and the nose length of the internal threaded joint (2) is L21, wherein L20 and L21 satisfy the following relationship: 0.15≤L20 / L21≤0.75; the first external sealing surface (11) has an included angle α1 with the axial direction of the oil jacket pipe threaded joint, and the included angle α1 satisfies the following relationship: 3.50°≤α1≤9.90°; the second external sealing surface (22) has an included angle β1 with the axial direction of the oil jacket pipe threaded joint, and the included angle β1 satisfies the following relationship: 3.50°≤β1≤9.90°; and the included angle α1 and the included angle β1 both satisfy the following relationship: 0°≤α1-β1≤1.5°; the internal sealing and shoulder part (c) comprises a first internal sealing surface (13) arranged on the external threaded joint (1) and a second internal sealing surface (24) arranged on the internal threaded joint (2), the first internal sealing surface (13) is sealingly matched with the second internal sealing surface (24); the first internal sealing surface (13) has an included angle α2 with the axial direction of the oil jacket pipe threaded joint, and the included angle α2 satisfies the following relationship: 3.50°≤α2≤9.90°; the second internal sealing surface (24) has an included angle β2 with the axial direction of the oil jacket pipe threaded joint, and the included angle β2 satisfies the following relationship: 3.50°≤β2≤9.90°; and the included angle α2 and the included angle β2 both satisfy the following relationship: 0°≤β2-α2≤1.5°.

2. A tubing-casing threaded joint according to claim 1, characterized in that, along the axial direction of the oil jacket pipe threaded joint, the length of the second external sealing surface (22) is L22, and L22 satisfies the following relationship: 2mm≤L22≤5mm.

3. A tubing-casing threaded joint according to claim 1, characterized in that, the first connecting surface (21) of the internal threaded joint (2) is connected with the pipe end surface (20) at one end and connected with the second external sealing surface (22) at the other end; the first connecting surface (21) comprises at least one of a conical surface, a cylindrical surface and an arc surface.

4. A tubing-casing threaded joint according to claim 1, characterized in that, the first external sealing surface (11) and the body outer peripheral surface (10) of the external threaded joint (1) have a second connecting surface; the second connecting surface and the first external sealing surface (11) are not on the same circumferential surface; or, The second connecting surface is on the same circumferential surface as the first outer sealing surface (11).

5. A tubing-casing thread joint according to any one of claims 1 to 4, characterized in that The threaded portion (b) comprises: a first thread (12) arranged on an outer wall surface of the outer threaded joint (1); a second thread (23) arranged on an inner wall surface of the inner threaded joint (2); the first thread (12) and the second thread (23) are threadedly engaged to threadedly connect the outer threaded joint (1) and the inner threaded joint (2); wherein, when the first thread (12) and the second thread (23) are threadedly engaged, first thread teeth of the first thread (12) and second thread teeth of the second thread (23) are engaged, and adjacent first thread teeth and second thread teeth have a flank clearance d between them, d satisfies the following relationship: 0.02mm≤d≤0.15mm.

6. A tubing-casing thread joint according to any one of claims 1 to 4, characterized in that A nose length of the outer threaded joint (1) is L10, and a distance from a midpoint of the second inner sealing surface (24) to the first butt shoulder surface (26) of the inner threaded joint (2) is L23, wherein L10 and L23 satisfy the following relationship: 0.25≤L23 / L10≤0.

9.

7. A tubing-casing threaded joint according to claim 1, characterized in that, In an axial direction of the oil casing threaded joint, a length of the second inner sealing surface (24) is L24, L24 satisfies the following relationship: 2mm≤L24≤5mm.

8. A tubing-casing threaded joint according to claim 6, characterized in that, The inner threaded joint (2) is further provided with a second connecting surface (25), one end of the second connecting surface (25) is connected with the second inner sealing surface (24), and the other end of the second connecting surface (25) is connected with the first butt shoulder surface (26); the second connecting surface (25) comprises at least one of a tapered surface, a cylindrical surface and an arc surface.

9. A tubing-casing threaded joint according to claim 6, characterized in that, The inner sealing and shoulder portion (c) further comprises a first shoulder surface (14) arranged on an end surface of the outer threaded joint (1) and connected with the first inner sealing surface (13), the first shoulder surface (14) is interference-fitted with the first butt shoulder surface (26); wherein, The first shoulder surface (14) has an included angle α3 with a vertical direction, and the included angle α3 satisfies the following relationship: 0°≤α3≤15°; The first butt shoulder surface (26) has an included angle β3 with the vertical direction, and the included angle β3 satisfies the following relationship: 0°≤β3≤15°; And the included angle α3 and the included angle β3 both satisfy the following relationship: 0°≤β3-α3≤1°.

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