CN210714506U

CN210714506U - Casing gas sealing threaded joint for shale gas well

Info

Publication number: CN210714506U
Application number: CN201921251042.7U
Authority: CN
Inventors: 王鹏; 冯耀荣; 韩礼红; 吉楠; 罗金恒; 邝献任
Original assignee: China National Petroleum Corp; CNPC Tubular Goods Research Institute
Current assignee: China National Petroleum Corp; CNPC Tubular Goods Research Institute
Priority date: 2019-08-02
Filing date: 2019-08-02
Publication date: 2020-06-09
Anticipated expiration: 2029-08-02

Abstract

The utility model discloses a casing gas-tight sealing threaded joint for shale gas wells, which adopts a small negative angle bearing surface, improves the tensile resistance of thread teeth, is suitable for lifting operation in the process of descending a shale gas well long-distance horizontal and big dog leg degree borehole casing, and is suitable for the characteristic of deep shale gas reservoir burial in China; the thread tooth form adopts a low positive angle guide surface, is easy to thread and buckle, has the anti-thread-buckling advantage, simultaneously takes the effect of increasing the thread compression load into consideration, and is suitable for the downward pressing operation of the shale gas well long-distance horizontal and big dog leg degree well casing in the downward entering process.

Description

Casing gas sealing threaded joint for shale gas well

[ technical field ] A method for producing a semiconductor device

The utility model belongs to the technical field of screwed joint, concretely relates to shale is airtight screwed joint of sleeve pipe for gas well.

[ background of the invention ]

The shale gas development in China has the characteristics of low cost control, long-distance horizontal well, big dogleg degree of well body, high-pressure large-displacement multi-stage fracturing, casing operation, well completion and the like. The whole service period of the casing bears the effects of rotary bending during running down, repeated lifting and running down, repeated liquid high internal pressure circulation during fracturing, non-uniform external pressure and shearing load of stratum and long-term gas low internal pressure during production. The shale gas well has comprehensive high-performance requirements on special threads of a sleeve and considering economical efficiency: anti-thread gluing, high torsion resistance, high compression resistance, non-uniform external pressure and shearing resistance, fatigue resistance and high pressure water/low pressure air sealing performance. The metal-metal main sealing structure, the tooth form and tooth flank clearance, the shoulder angle and the sealing surface interference amount and other thread key parameters need to be subjected to targeted optimization design. The conventional casing special thread applied to the shale gas well has the disadvantages of excessive or insufficient performance indexes, poor working condition applicability and high cost, and cannot meet the engineering requirements of safe and efficient development of shale gas.

[ Utility model ] content

The utility model aims to overcome the defects of the prior art and provide a casing gas-tight sealing special threaded joint for a shale gas well; the connector replaces the existing special casing threads, and has the comprehensive high-performance characteristics of thread gluing resistance, high torsion resistance, high compression resistance, non-uniform external pressure and shearing resistance, fatigue resistance, high-pressure water/low-pressure air tightness and the like aiming at the working condition characteristics of shale gas well drilling, casing running, volume fracturing and production.

In order to achieve the above purpose, the utility model adopts the following technical scheme to realize:

the casing air-tight seal threaded connector for the shale gas well comprises a casing coupling and a casing which are coaxial, wherein the casing coupling is sleeved outside the casing, and the casing coupling and the casing are in threaded fit; along the axial direction of the casing, the contact parts of the casing coupling and the casing are a first contact part, a second contact part and a third contact part which are connected in sequence; in the second contact part, the included angle between the external thread bearing surface of the sleeve and the radial direction of the sleeve is-3 degrees, and the included angle between the external thread guide surface of the sleeve and the radial direction of the sleeve is 12 degrees.

The utility model discloses a further improvement lies in:

preferably, in the first contact part, a first crest gap is arranged between the crest of the external thread of the casing and the root of the internal thread of the casing coupling; in the second contact part, a second crest gap is arranged between the crest of the external thread of the casing and the root of the internal thread of the casing collar, and the width of the first crest gap is greater than that of the second crest gap.

Preferably, the width of the second crest gap ranges from 0.05mm to 0.2 mm.

Preferably, a flank clearance is provided between the male thread guide surface of the casing and the female thread guide surface of the casing collar.

Preferably, the width of the interproximal space ranges from 0.02mm to 0.1 mm.

Preferably, in the third contact part, the casing coupling comprises a complete thread section, a partial thread groove, a transition section and a conical surface section which are connected in sequence, and the casing comprises an inclined plane section and an arc surface section which are connected in sequence; the inclined plane section is contacted with the complete thread section, and the cambered surface section is simultaneously matched with a part of tooth socket, the transition section and the conical surface section.

Preferably, a gap is arranged between the arc surface section and the partial tooth socket, and a gap is arranged between the arc surface section and the transition section.

Preferably, the sum of the lengths of the partial alveolus and the transition section in the axial direction of the cannula is a pitch of 0.8 to 1.5 times.

Preferably, the cambered surface section is contacted with the conical surface section, and the cambered surface section and the conical surface section form a cambered-conical surface metal radial interference sealing structure.

Preferably, the bottom contact surface of the engagement of the casing and the casing collar is a shoulder surface, and the included angle between the shoulder surface and the radial direction of the casing is-4 to-10 degrees.

Compared with the prior art, the utility model discloses following beneficial effect has:

Furthermore, no matter the first contact part or the second contact part, gaps are formed between the tooth top and the tooth bottom, gaps are also formed between the guide surfaces, and large gaps can effectively reduce the load of the external thread teeth, reduce the deformation of the thread teeth and improve the anti-thread gluing performance.

Further, in the third section contact portion, the casing collar is divided into four portions according to the requirements of assembly, and the casing is divided into two portions which are respectively matched to form different corresponding structures.

Furthermore, gaps are formed among the arc surface section, the partial tooth sockets and the transition section, the common length of the partial tooth sockets and the common length of the transition section are limited, the thread grease is conveniently stored, the cutter is withdrawn during thread machining, and the bearing area of the dangerous section of the coupling is increased.

Furthermore, the cambered surface section is in contact with the conical surface section to form a tight sealing structure, so that the sealing performance is improved, Gaussian distribution sealing contact pressure is formed, the sealing contact part is far away from the shoulder, the mechanical damage risk in the screwing-on process is reduced, the sealing contact pressure and the sealing contact width are kept under the action of a composite load, the water sealing performance of the fracturing load cycle of the shale gas well and the conditions of non-uniform external extrusion and shearing load is improved, and the requirement on the air sealing performance of the shale gas well in the production stage is met.

Furthermore, the low negative angle shoulder is adopted, the mechanical performance of the threaded joint is guaranteed, the nose deformation is controlled, the stress concentration is reduced, the compression resistance of the joint is improved, the sealing robustness of the joint is considered, the upper buckling position control is facilitated, the over-torque resistance is improved, and the cleaning is easy.

[ description of the drawings ]

Fig. 1 is a schematic view of a cross-sectional structure of a threaded joint according to the present invention;

fig. 2 is a schematic view of the thread and seal form of the threaded joint of the present invention;

FIG. 3 is a cloud of equivalent stress distributions for a threaded joint seal and shoulder structure after make-up installation.

Wherein: 1-casing collar; 2-a sleeve; 3-partial alveolus; 4-a radial interference seal structure; 5-shoulder surface; 6-external thread bearing surface; 7-external thread guide surface; 8-second crest gap; 9-flank space; 10-a first contact portion; 11-a second contact portion; 12-a third contact portion; 13-internal thread guide surface; 14-first crest gap; 15-inclined plane section; 16-arc surface section; 17-a complete thread segment; 18-a transition section; 19-conical surface section.

[ detailed description ] embodiments

The present invention will be described in further detail with reference to the accompanying drawings and specific embodiments.

Referring to fig. 1, the utility model discloses a casing gas sealing screwed joint for shale gas well; the threaded joint comprises a casing coupling 1 and a casing 2, wherein the casing coupling 1 and the casing 2 are both steel casing joints; along the axial direction of the casing 2, the casing collar 1 and the casing 2 are divided into three parts according to different degrees of contact, namely a first contact part 10, a second contact part 11 and a third contact part 12; the external thread 13 gradually appears on the outer surface of the casing 2 in the first contact part 10, and the root of the external thread 13 gradually becomes deeper, so that the internal thread of the casing collar 1 and the external thread of the casing 2 are not completely meshed in the part, and a first crest gap 14 is arranged between the crest of the external thread and the root of the internal thread in the first contact part 10; the internal thread of the casing coupling 1 in the second contact part 11 is completely contacted with the external thread of the casing 2, the included angle between the external thread bearing surface 6 of each external thread in the second contact part 11 and the radial direction of the casing 2 is-3 degrees, the included angle between the external thread guide surface 7 of each external thread and the radial direction of the casing 2 is 12 degrees, and the thread profile of the thread guide surface 7 can improve the tensile property of the thread and give consideration to the thread buckling smoothness and the compression resistance. A second crest gap 8 is arranged between the bottom of the teeth of the internal thread of the casing coupling 1 and the crest of the external thread of the casing 2 in the second contact part 11, a flank gap 9 is arranged between the external thread guide surface 7 of the casing 2 and the internal thread guide surface 13 of the casing coupling 1, the range of the second crest gap 8 is 0.05 mm-0.2 mm, and the range of the flank gap 9 is 0.02 mm-0.1 mm; as can be seen with reference to fig. 1, the width of first crest gap 14 gradually decreases, but the width of first crest gap 14 is always greater than second crest gap 8; the big clearance structure in pin thread crest of this part improves and goes up the smooth and easy nature of detaining, effectively protects external screw thread.

Referring to fig. 2, the casing 2 in the third contact portion 12 includes an inclined plane section 15 and a cambered surface section 16 which are fixedly connected in sequence along the axial direction of the casing 2, and the third contact portion 12 of the casing collar 1 includes a complete thread section 17, a partial thread groove 3, a transition section 18 and a tapered surface section 19 which are connected in sequence. The inclined plane section 15 is matched with the complete thread section 17, because the inclined plane section 15 is inclined relative to the axis of the sleeve 2, a part of the thread groove of the complete thread section 17 is contacted with the inclined plane section 15, and a part of the thread top of the complete thread section 17 is contacted with the inclined plane end 17; the cambered surface section 16 is matched with the partial thread groove 3, the transition section 18 and the conical surface section 19, because the inclined plane section 17 is inclined relative to the axis of the casing 2, a gap is formed between the cambered surface section 16 and the casing coupling 1, namely a gap is formed between the partial thread groove 3 and the transition section 18 and the cambered surface section 16 along the radial direction of the casing 2, the gap enables the part to have the functions of tool withdrawal and thread grease storage, and the sum of the lengths of the partial thread groove 3 and the transition section 18 is 0.8-1.5 times of thread pitch; the transition section 12 comprises a part of crest and an inclined section, the inclined section is connected with the conical section 19, the conical section 19 is tightly contacted with the cambered section 16, and the cambered-conical metal radial interference sealing structure 4 is formed, wherein the plane of the part of the conical section 19 of the finger sleeve hoop 1 is inclined relative to the axis of the sleeve 2 to form the conical section 19, and the cambered section 16 is a circle with a larger radius, so that the part of the conical section 19 contacted with the cambered section 16 forms a sealing surface.

The final meshed bottom end surface of the sleeve 2 and the sleeve coupling 1 is a shoulder surface 5, the shoulder surface 5 adopts a low negative angle shoulder structure, and the low negative angle is specifically-4 degrees to-10 degrees; the low negative angle here is the angle between the contact surface of the shoulder and the radial direction of the sleeve 2.

The utility model discloses in, the big clearance structure of pin thread addendum improves and detains smooth and easy nature, effectively protects the external screw thread. The incomplete thread tooth socket effectively ensures reasonable distribution of thread grease at the sealing part, takes account of thread processing tool withdrawal and improves the dangerous cross-sectional area of the coupling. The cambered surface-conical surface metal sealing surface realizes Gaussian contact pressure distribution, improves the anti-thread gluing property of the sealing surface, reduces the risk of mechanical damage of the upper-thread sealing surface, and ensures the sealing performance of the joint in stretching, bending and non-uniform load states. The low negative angle circular bead is convenient to process, the deformation of the thread nose end is effectively controlled, the sealing robustness of the sealing surface is improved, the anti-over-twisting performance is improved, and the thread cleaning is facilitated. The inner surface of the joint is flat, so that the flow state of fluid in the pipe body at the joint part is stable, and the erosion resistance is improved. Furthermore, the pipe body butt joint position of the external thread of the sleeve and the internal thread of the sleeve is provided with an expanded conical surface which is parallel and level to the joint position of the inner surface of the coupling, so that the fluid erosion resistance of the inner surface of the joint is improved.

The special screwed joint can adapt to the selection of sleeves with different outer diameters, wall thicknesses and steel grades, the numerical control machine tool is adopted for machining, and the thickness of the internal thread coating layer of the sleeve coupling 1 is controlled within the range of 15-25 um. When the universal casing pipe is buckled, universal casing pipe thread grease is evenly smeared at two ends, the clamping thread is close to the pipe body side, the coupling is close to the factory end side, and the optimal control torque is adopted for buckling on site.

The above description is only a preferred embodiment of the present invention, and should not be taken as limiting the invention, and any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. The casing air-tight seal threaded connector for the shale gas well is characterized by comprising a casing coupling (1) and a casing (2) which are coaxial, wherein the casing coupling (1) is sleeved outside the casing (2) and is in threaded fit with the casing (2); the contact parts of the casing joint (1) and the casing (2) are a first contact part (10), a second contact part (11) and a third contact part (12) which are connected in sequence along the axial direction of the casing (2); in the second contact part (11), an included angle between the external thread bearing surface (6) of the sleeve (2) and the radial direction of the sleeve (2) is-3 degrees, and an included angle between the external thread guide surface (7) of the sleeve (2) and the radial direction of the sleeve (2) is 12 degrees.

2. The shale gas well casing gas sealing threaded joint as claimed in claim 1, characterized in that a first crest gap (14) is arranged between the crest of the external thread of the casing (2) and the root of the internal thread of the casing collar (1) in the first contact part (10); in the second contact part (11), a second crest gap (8) is arranged between the crest of the external thread of the casing pipe (2) and the root of the internal thread of the casing pipe coupling (1), and the width of the first crest gap (14) is larger than that of the second crest gap (8).

3. The shale gas well casing gas sealing threaded joint as set forth in claim 2, wherein the width of the second crest gap (8) ranges from 0.05mm to 0.2 mm.

4. The shale gas well casing gas sealing threaded joint as claimed in claim 1, characterized in that a flank clearance (9) is provided between the externally threaded guide surface (7) of the casing (2) and the internally threaded guide surface (13) of the casing collar (1).

5. The shale gas well casing gas sealing threaded joint as claimed in claim 4, wherein the width of the flank gap (9) ranges from 0.02mm to 0.1 mm.

6. The shale gas well casing gas sealing threaded joint as claimed in claim 1, characterized in that in the third contact part (12), the casing collar (1) comprises a complete thread section (17), a partial thread groove (3), a transition section (18) and a conical section (19) which are connected in sequence, and the casing (2) comprises an inclined plane section (15) and a cambered surface section (16) which are connected in sequence; the inclined plane section (15) is contacted with the complete thread section (17), and the cambered surface section (16) is simultaneously matched with the partial tooth socket (3), the transition section (18) and the conical surface section (19).

7. The shale gas well casing gas-tight threaded joint as claimed in claim 6, characterized in that a gap is provided between the cambered section (16) and the partial socket (3), and a gap is provided between the cambered section (16) and the transition section (18).

8. The shale gas well casing gas sealing threaded joint as claimed in claim 6, wherein the sum of the lengths of the partial thread groove (3) and the transition section (18) in the axial direction of the casing (2) is a pitch of 0.8 to 1.5 times.

9. The shale gas well casing gas-tight threaded joint as set forth in claim 6, characterized in that the cambered surface section (16) and the conical surface section (19) are in contact, and both form a cambered-conical metal radial interference sealing structure (4).

10. The shale gas well casing gas sealing threaded joint according to any one of claims 1 to 9, characterized in that the bottom end contact surface where the casing (2) and the casing collar (1) are engaged is a shoulder surface (5), and the included angle between the shoulder surface (5) and the radial direction of the casing (2) is-4 ° to-10 °.