Threaded joint for oil casing

Abstract

The utility model provides an oil casing pipe screwed joint. The oil casing threaded connector is provided with an axis and comprises an inner threaded connector, at least part of the outer surface of the inner threaded connector is an inclined surface, the inclined surface extends from the pipe end of the inner threaded connector to the direction where a pipe body of the inner threaded connector is located along the axis, and the distance between the inclined surface and the axis is gradually decreased. At least part of the external thread connector extends into the internal thread connector, the external thread connector is connected with the internal thread connector, and a thickening part is arranged on the inner surface of at least part of the external thread connector along the axis so as to increase the area of the dangerous section of the external thread connector. According to the technical scheme, the oil casing pipe screwed joint can increase the annular clearance of a pipe column and improve the connection strength of the oil casing pipe screwed joint.

Description

Technical Field

[0001] The utility model relates to the technical field of oil casing, in particular to an oil casing threaded joint. Background Art

[0002] In the prior art, the outer peripheral surface of the internal threaded joint of the special clearance oil casing threaded joint or the straight connection oil casing threaded joint is a cylindrical surface, the size of which is a certain value, and the outer seal has a certain interference (such as Figure 7 As shown), when the internal threaded joint 1 expands outward after being screwed together (as shown Figure 8 f), the outer diameter of the internal threaded joint increases, resulting in a reduction in the annular gap; at the same time, the dangerous cross-section of the external threaded joint 2 of the prior art is small (as shown in FIG. Figure 8 h and g), thus limiting the improvement of connection strength.

[0003] Chinese patent publication number CN219774077U discloses a threaded joint for oil casing, which includes an external threaded joint and an internal threaded joint, and has both an external sealing structure and an internal sealing structure. When screwed together, the internal threaded joint 1 expands outward, increasing the outer diameter of the internal threaded joint and reducing the annular space gap. In addition, the inner surface dangerous cross-sectional area of ​​the external threaded joint 2 is small, thereby limiting the improvement of the connection strength. Utility Model Content

[0004] The main purpose of the utility model is to provide an oil casing threaded joint, which can increase the annular space gap of the pipe column and improve the connection strength of the oil casing threaded joint.

[0005] In order to achieve the above-mentioned purpose, the utility model provides an oil casing threaded joint, which has an axis and includes: an internal threaded joint, at least a portion of the outer surface of the internal threaded joint is an inclined surface, along the axis, the inclined surface extends from the pipe end of the internal threaded joint toward the direction of the pipe body of the internal threaded joint, and the distance between the inclined surface and the axis gradually decreases; an external threaded joint, at least a portion of the external threaded joint extends into the internal threaded joint, the external threaded joint is connected to the internal threaded joint, and along the axis, at least a portion of the inner surface of the external threaded joint is provided with a thickened portion to increase the area of ​​the dangerous cross-section of the external threaded joint.

[0006] Furthermore, the outer surface of the internal threaded joint includes a cylindrical surface and an inclined surface. Along the axis, the inclined surface extends from the pipe end of the internal threaded joint to the cylindrical surface and is connected to the cylindrical surface.

[0007] Furthermore, the outer surface of the internal thread joint is an inclined surface.

[0008] Furthermore, the inclined surface has an inclination angle θ, and the inclination angle θ ranges from 0.3° to 5°.

[0009] Furthermore, a length L1 of the inclined surface on the axis ranges from 30 mm to 100 mm.

[0010] Furthermore, along the axis, the thickened portion extends from the pipe end of the external threaded joint to the pipe body of the external threaded joint.

[0011] Furthermore, the thickened portion is connected to the inner surface of the external threaded joint, and a thickness D of the thickened portion in a radial direction of the oil casing threaded joint ranges from 1% OD to 10% OD.

[0012] Furthermore, the length L2 of the thickened portion on the axis ranges from 50 mm to 200 mm.

[0013] Furthermore, along the axis, an outer sealing portion, a threaded portion and an inner sealing portion are sequentially formed between the external thread joint and the internal thread joint. The external thread joint and the internal thread joint are connected through the threaded portion, and the external thread joint and the internal thread joint are interference fit to form the outer sealing portion and the inner sealing portion.

[0014] By applying the technical solution of the present invention, after the oil casing threaded joint is tightened, the problem of the outer diameter of the internal threaded joint becoming larger due to the outward expansion of the internal threaded joint can be avoided, thereby increasing the annular space gap of the pipe column; at the same time, the inner surface of the external threaded joint is provided with a thickened portion (such as Figure 1 As shown in b, a certain range of the inner surface of the external threaded joint is thickened), so that the area of ​​the dangerous section of the external threaded joint (as shown in e) is increased, thereby improving the connection strength of the oil casing threaded joint. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The drawings constituting part of this application are provided to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are provided to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0016] Figure 1 A structural schematic diagram of an embodiment of an oil casing threaded joint of the present utility model is shown;

[0017] Figure 2 Shown Figure 1 A schematic structural diagram of an internal threaded joint of an oil casing threaded joint;

[0018] Figure 3 Shown Figure 1 Schematic diagram of the structure of the external threaded joint of the oil casing threaded joint;

[0019] Figure 4 Shown Figure 1 The enlarged view of the c point of the oil casing threaded joint;

[0020] Figure 5 Shown Figure 1 The enlarged view of point d of the oil casing threaded joint;

[0021] Figure 6 The figure shows the structure of the embodiment of the oil casing threaded joint after being screwed together;

[0022] Figure 7 Shows the structural diagram of the existing patented oil pipe threaded joint;

[0023] Figure 8 The diagram shows the structure of the existing patented oil pipe threaded joint after being screwed together.

[0024] The above drawings include the following reference numerals:

[0025] 1. Internal thread joint; 2. External thread joint; 3. Inclined surface; 4. Thickened portion; 5. External sealing portion; 6. Threaded portion; 7. Internal sealing portion. DETAILED DESCRIPTION

[0026] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments in this application can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0027] It should be noted that the oil casing threaded joint (petroleum pipe threaded joint) of the embodiment of the present utility model is applicable to special clearance oil casing threaded joints and direct connection oil casing threaded joints.

[0028] like Figures 1 to 6 As shown, an embodiment of the present invention provides an oil casing threaded joint. The oil casing threaded joint has an axis L and includes: an internal threaded joint 1, at least a portion of the outer surface of the internal threaded joint 1 is an inclined surface 3, along the axis L, the inclined surface 3 extends from the pipe end of the internal threaded joint 1 toward the pipe body of the internal threaded joint 1, and the distance between the inclined surface 3 and the axis L gradually decreases (as shown in FIG. Figure 1 As shown in a); the external threaded joint 2, at least part of the external threaded joint 2 extends into the internal threaded joint 1, the external threaded joint 2 is connected to the internal threaded joint 1, along the axis L, at least part of the inner surface of the external threaded joint 2 is provided with a thickened portion 4, to increase the area of ​​the dangerous section e of the external threaded joint 2.

[0029] In the above technical solution, after the oil casing threaded joint is tightened, the problem of the outer diameter of the internal threaded joint 1 becoming larger due to the outward expansion of the internal threaded joint 1 can be avoided, thereby increasing the annular space gap of the pipe column; at the same time, the inner surface of the external threaded joint 2 is provided with a thickened portion 4 (such as Figure 1As shown in b, a certain range of the inner surface of the external threaded joint 2 is thickened), so that the area of ​​the dangerous section of the external threaded joint 2 (as shown in e) is increased, thereby improving the connection strength of the oil casing threaded joint.

[0030] The oil casing threaded joint of the embodiment of the utility model can increase the annular space gap based on the need to limit the size of the oil casing joint, thereby improving the cementing quality, and at the same time can also maximize the connection strength of the oil casing joint to meet the needs of complex oil and gas wells.

[0031] Specifically, in the embodiment of the present invention, the threads of the internal threaded joint 1 are processed inside the pipe end, and the threads of the external threaded joint 2 are processed outside the pipe end or the coupling.

[0032] like Figure 1 and Figure 2 As shown, in the embodiment of the present invention, the outer surface of the internal threaded joint 1 includes a cylindrical surface and an inclined surface 3. Along the axis L, the inclined surface 3 extends from the pipe end of the internal threaded joint 1 to the cylindrical surface and is connected to the cylindrical surface.

[0033] In the above technical solution, when the internal threaded joint 1 and the external threaded joint 2 are tightened, the design of the inclined surface 3 can avoid excessive increase in the outer diameter of the internal threaded joint 1, thereby avoiding the reduction of the annular space gap due to the increase in the outer diameter of the internal threaded joint 1, maintaining sufficient annular space, which is conducive to improving the cementing quality and the operating efficiency of the oil well.

[0034] In one embodiment, the outer surface of the internal threaded joint 1 is entirely an inclined surface 3. In this way, an excessive increase in the outer diameter of the internal threaded joint 1 can also be avoided.

[0035] like Figure 2 As shown, in the embodiment of the present invention, the inclined surface 3 has an inclined angle θ, and the range of the inclined angle θ is 0.3° to 5°.

[0036] In the above technical solution, the selection of the tilt angle θ is crucial for controlling the degree of expansion of the internal threaded joint 1 during the tightening process. When the degree of expansion is minimal during the tightening process, a larger tilt angle (e.g., 5°) can be selected, while when the degree of expansion is maximum during the tightening process, a smaller tilt angle (e.g., 0.3°) can be selected, thereby precisely controlling the change in the outer diameter of the internal threaded joint and preventing a reduction in the annular gap.

[0037] Furthermore, the adjustable range of the tilt angle θ (0.3° to 5°) provides design flexibility, allowing the tilt angle to be adjusted to optimize the performance of the threaded joint according to different well conditions and operational requirements. For example, a smaller tilt angle can be used when a larger annular clearance is required.

[0038] like Figure 2As shown, in the embodiment of the present invention, the length L1 of the inclined surface 3 on the axis L is in the range of 30 mm to 100 mm.

[0039] In the above technical solution, the length L1 of the inclined surface 3 is designed to be 30mm to 100mm, which helps control the degree of expansion of the internally threaded joint 1 during tightening and avoids the reduction of the annular clearance caused by excessive expansion. A properly lengthed inclined surface 3 ensures that the joint remains within the design dimensional range during the contact and tightening process, thereby maintaining the expected annular clearance, facilitating smooth cementing operations and improving cementing quality.

[0040] like Figure 3 As shown, in the embodiment of the present invention, along the axis L, the thickened portion 4 extends from the pipe end of the external threaded joint 2 to the pipe body of the external threaded joint 2 .

[0041] In the above technical solution, the extension of the thickened portion 4 increases the shear and tensile strength, thereby ensuring the connection stability under high load conditions and reducing the risk of connection failure caused by uneven force. The setting of the thickened portion 4 directly increases the area of ​​the dangerous section e of the threaded joint, thereby improving the load capacity of the threaded joint.

[0042] like Figure 3 As shown, in the embodiment of the present invention, the thickened portion 4 is connected to the inner surface of the external threaded joint 2, and the thickness D of the thickened portion 4 in the radial direction of the oil casing threaded joint ranges from 1% OD to 10% OD.

[0043] In the above technical solution, the introduction of the thickened portion 4, especially the thickening in the radial direction, significantly increases the material volume of the external threaded joint 2, thereby improving the connection strength of the threaded joint. In this way, the threaded joint has better structural stability and fatigue resistance when subjected to high loads, such as tensile or rotational forces.

[0044] Furthermore, the range of the radial thickness D of the thickened portion 4 needs to be selected to find a balance between increasing material cost and improving performance. A suitable range of thickness D can control manufacturing costs while ensuring connection performance and improve economic benefits.

[0045] It should be noted that, in the embodiment of the present invention, OD is the outer diameter of the tube body.

[0046] like Figure 3 As shown, in the embodiment of the present invention, the length L2 of the thickened portion 4 on the axis L is in the range of 50 mm to 200 mm.

[0047] In the above technical solution, by controlling the length L2 of the thickened portion 4, the force distribution can be optimized when the threaded joint is tightened to avoid excessive local stress. The setting of the L2 range helps to disperse the stress of the threaded joint when it is subjected to tension, compression and torsional forces, reduce the stress concentration at the dangerous section e, reduce the risk of thread damage, and extend the service life of the threaded joint.

[0048] Furthermore, the design of oil pipe threaded joints often requires a balance between improved performance and size constraints. Setting the length L2 of the thickened portion 4 between 50 mm and 200 mm improves overall performance without significantly increasing the material required for the threaded joint, making it suitable for complex, size-constrained oil and gas well operations.

[0049] Specifically, in the embodiment of the present invention, by providing the inclined surface 3, after the oil casing threaded joint is tightened, the outer diameter of the internal threaded joint 1 caused by the outward expansion of the internal threaded joint 1 can be prevented from increasing, thereby ensuring that the outer diameter of the oil casing threaded joint is equal to the outer diameter of the coupling.

[0050] like Figure 1 、 Figure 4 and Figure 5 As shown, in an embodiment of the present invention, along the axis L, an outer sealing portion 5, a threaded portion 6 and an inner sealing portion 7 are sequentially formed between the external threaded joint 2 and the internal threaded joint 1. The external threaded joint 2 and the internal threaded joint 1 are connected by the threaded portion 6, and the external threaded joint 2 and the internal threaded joint 1 are interference fit to form the outer sealing portion 5 and the inner sealing portion 7.

[0051] In the above technical solution, the double sealing design can significantly improve the sealing performance of the threaded joint, effectively prevent oil and gas leakage even in a high-pressure environment, and improve the safety and efficiency of the operation; and through the connection of the threaded portion 6 and the interference fit of the outer sealing portion 5 and the inner sealing portion 7, the embodiment of the utility model enhances the connection strength between the external threaded joint 2 and the internal threaded joint 1, so that it can withstand greater tension, compression and torsional forces, ensure structural stability under complex geological conditions, and extend the service life of the threaded joint.

[0052] Specifically, in the embodiment of the present invention, the threaded joint has an outer sealing portion 5 (such as Figure 1 As shown in c), the threaded joint has an inner sealing portion 7 with a certain amount of interference (as shown in Figure 1 (as shown in d).

[0053] Specifically, if Figure 4 As shown, in the embodiment of the present invention, the interference amount δ of the outer sealing portion 5 ranges from 0.3 mm to 1.1 mm.

[0054] In one specific embodiment, the pipe body utilizes a φ293.45×23.55mm casing with a steel grade of 140HC, limiting the outer diameter of the coupling to 310mm. A certain range of the outer surface of the end of the internal threaded joint 1 is designed as an inclined surface, with an inclination angle θ of 0.5° and an inclined surface length L1 of 85mm. A certain range of the inner surface of the external threaded joint 2 is thickened, with a thickening length L2 of 160mm. After the internal threaded joint 1 and the external threaded joint 2 are screwed together, the outer diameter of the joint does not exceed 310mm of the outer diameter of the coupling, achieving a connection efficiency of 75% of the pipe body, a connection strength and compressive strength of 14474kN, an internal pressure airtightness exceeding 139Mpa, an external pressure resistance exceeding 145Mpa, and a bending resistance exceeding 20° / 30 meters.

[0055] From the above description, it can be seen that the above embodiment of the present invention achieves the following technical effects: after the oil casing threaded joint is tightened, the problem of the outer diameter of the internal threaded joint becoming larger due to the outward expansion of the internal threaded joint can be avoided, thereby increasing the annular space gap of the pipe column; at the same time, the inner surface of the external threaded joint is provided with a thickened portion (such as Figure 1 As shown in b, a certain range of the inner surface of the external threaded joint is thickened), so that the area of ​​the dangerous section of the external threaded joint (as shown in e) is increased, thereby improving the connection strength of the oil casing threaded joint.

[0056] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that the present invention is susceptible to various modifications and variations. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A threaded joint for oil casing, characterized in that: The oil casing threaded joint has an axis (L), and the oil casing threaded joint comprises: An internal threaded joint (1), wherein at least a portion of the outer surface of the internal threaded joint (1) is an inclined surface (3), and along the axis (L), the inclined surface (3) extends from the pipe end of the internal threaded joint (1) toward the pipe body of the internal threaded joint (1), and the distance between the inclined surface (3) and the axis (L) gradually decreases; An external threaded joint (2), at least a portion of which extends into the internal threaded joint (1), is connected to the internal threaded joint (1), and along the axis (L), at least a portion of the inner surface of the external threaded joint (2) is provided with a thickened portion (4) to increase the area of ​​a dangerous section (e) of the external threaded joint (2).

2. The oil casing threaded joint according to claim 1, characterized in that: The outer surface of the internal threaded joint (1) comprises a cylindrical surface and the inclined surface (3), and along the axis (L), the inclined surface (3) extends from the pipe end of the internal threaded joint (1) to the cylindrical surface and is connected to the cylindrical surface.

3. The oil casing threaded joint according to claim 1, characterized in that: The outer surface of the internal thread joint (1) is the inclined surface (3).

4. The oil casing threaded joint according to claim 1, characterized in that: The inclined surface (3) has an inclination angle θ, and the inclination angle θ ranges from 0.3° to 5°.

5. The oil casing threaded joint according to claim 1, characterized in that: The length L1 of the inclined surface (3) on the axis (L) ranges from 30 mm to 100 mm.

6. The oil casing threaded joint according to any one of claims 1 to 5, characterized in that: Along the axis (L), the thickened portion (4) extends from the pipe end of the external threaded joint (2) to the pipe body of the external threaded joint (2).

7. The oil casing threaded joint according to any one of claims 1 to 5, characterized in that: The thickened portion (4) is connected to the inner surface of the external threaded joint (2), and the thickness D of the thickened portion (4) in the radial direction of the oil casing threaded joint ranges from 1% OD to 10% OD.

8. The oil casing threaded joint according to any one of claims 1 to 5, characterized in that: The length L2 of the thickened portion (4) on the axis (L) ranges from 50 mm to 200 mm.

9. The oil casing threaded joint according to any one of claims 1 to 5, characterized in that: Along the axis (L), an outer sealing portion (5), a threaded portion (6) and an inner sealing portion (7) are sequentially formed between the outer threaded joint (2) and the inner threaded joint (1); the outer threaded joint (2) and the inner threaded joint (1) are connected via the threaded portion (6); the outer threaded joint (2) and the inner threaded joint (1) are interference-fitted to form the outer sealing portion (5) and the inner sealing portion (7).

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