CN111379528A - An expansion casing joint with improved liquid sealing performance - Google Patents

Abstract

The invention discloses an expansion casing joint for improving liquid sealing performance, comprising a male threaded joint and a female threaded joint; the male threaded joint is sequentially provided with a first negative angle torque shoulder and a first API circle from the end to the outside. Thread and first barb-shaped thread, the female threaded joint is sequentially provided with a second negative angle torque shoulder, a second API round thread and a second barb-shaped thread matched with the male threaded joint from the inward end. thread; a sealing structure is arranged between the first API round thread and the first barb thread. The joint is suitable for the joint structure of the expansion casing. It adopts the combination of the barb thread with strong connection and the API round thread with good sealing performance, and provides an expansion casing joint suitable for expanding the diameter for the expansion casing. The casing joint has high strength, good sealing performance and easy processing.

Description

An expansion casing joint with improved liquid sealing performance

technical field

The invention belongs to the field of oil and gas exploration and development, and particularly relates to an expansion casing joint for improving liquid sealing performance.

Background technique

In the process of oil and gas exploration and development, there are a large number of deep wells, ultra-deep wells and special wells with complex strata, and the level of the running casing increases with the increase of the well depth, resulting in the continuous reduction of the diameter of the wellbore and the lack of space for subsequent operations. , and ultimately cannot achieve the desired purpose layer economically. In order to overcome this problem, the expansion casing technology has emerged. The expansion casing technology is a technology that uses the expansion cone to expand the diameter to meet the engineering requirements through cold extrusion and expansion in the downhole, with the ultimate goal of realizing a single well diameter. This technology can increase the depth of drilling, effectively reduce the loss of well diameter, and shorten the time of well construction and the cost of drilling.

One of the core and difficult points of expansion casing technology is expansion casing connection, which requires that the pipe threaded joint connecting the casing still has a certain connection strength and sealing ability to liquid after the expansion and deformation of the casing pipe body. Common standard pipe threads and current special thread joints for conventional casings cannot meet this requirement.

Currently known expansion casing joints mainly rely on rubber rings to achieve sealing, and a schematic diagram of the structure is shown in Figure 1 . The joint consists of a male threaded joint with barbed threads and a female threaded joint, and the male threaded joint is also provided with a sealing groove and a torque shoulder. The connection performance of the joint structure is realized by the barb thread, the sealing performance is mainly realized by the sealing rubber ring, and the torque control is realized by the torque shoulder. During the expansion process of the casing string, this expansion casing joint sealed with an elastic sealing ring has the following disadvantages: (1) the rubber ring is easily squeezed out of the sealing groove by the end of the male thread during the casing make-up process; (2) After the expansion diameter of the casing becomes larger, the rubber ring is easy to break. These factors make the reliability of this elastic rubber ring sealing method low, and the sealing performance of the expansion casing joint cannot be ensured during the on-site construction process. After the sealing problem, the expected liquid pressure in the expansion casing cannot be achieved, which can easily lead to the casing. Inflation failed.

Therefore, it is necessary to develop an expansion casing joint with good sealing performance, high connection strength and easy processing.

SUMMARY OF THE INVENTION

In order to solve the problem of poor sealing performance in the prior art, the present invention provides an expansion casing joint with improved liquid sealing performance. The combination of the improved API round thread provides an expansion casing joint suitable for diameter expansion for the expansion casing. The expansion casing joint has high strength, good sealing performance and is easy to process.

In order to achieve the above object, the present invention adopts the following technical solutions:

An expansion casing joint with improved liquid sealing performance, comprising a male threaded joint and a female threaded joint;

The male threaded joint is sequentially provided with a first negative angle torque shoulder, a first API round thread and a first barb thread from the end outward, and the female threaded joint is sequentially provided with the a second negative angle torque shoulder, a second API round thread and a second barb thread that are matched with the male threaded joint; an elastic sealing structure is arranged between the first API round thread and the first barb thread; The first API round thread and the second API round thread are in interference fit.

As a further improvement of the present invention, the wall thickness of the male threaded joint is greater than the wall thickness of the female threaded joint.

As a further improvement of the present invention, the circular thread structure includes a tooth top, a tooth bottom and a tooth flank connected in sequence, and the first tooth top of the male threaded joint and the second tooth bottom of the female threaded joint form a metal-to-metal sealing structure the interference fit and produce a close contact on the flanks of the teeth.

As a further improvement of the present invention, the elastic sealing structure includes a sealing groove, a sealing surface and a sealing body, the sealing groove is filled with and presses the sealing body outward, and the sealing body presses the sealing surface to form a seal.

As a further improvement of the present invention, the sealing groove is arranged on the male threaded joint, and the sealing surface is arranged on the female threaded joint.

As a further improvement of the present invention, the sealing body is an elastic sealing ring, soft metal or thread grease.

As a further improvement of the present invention, the barb thread is a single hook thread with a negative angle, comprising a barb thread hook surface, a barb thread hook tip and a barb thread guide surface connected in sequence.

As a further improvement of the present invention, the bearing surface angle of the hook surface of the barb-shaped thread is -15°～-20°, the taper of the thread is 1:(20-25), the hook tip of the barb-shaped thread is an arc surface, The declination angle of the hook thread guide surface is 10°～25°.

Preferably, the bearing surface angle of the barb-shaped thread hook surface is -18°, and the off-angle of the barb-shaped thread guide surface is 20°.

As a further improvement of the present invention, the first negative-angle torque shoulder of the male threaded joint is in interference contact with the second negative-angle torque shoulder of the female threaded joint; the angle of the first negative-angle torque shoulder is −20 °～﹣25°.

Compared with the existing technology, it has the following advantages:

The joint structure of the present invention has a triple sealing structure in total, wherein the API round thread is the main metal seal, the negative angle torque shoulder is the auxiliary metal seal, and the seal in the sealing groove is an elastic seal. The combination of the barb thread with strong connection and the API round thread with good sealing performance is adopted to provide an expansion casing joint suitable for expanding the diameter of the expansion casing. The expansion casing joint has high strength and good sealing performance. Also easy to process. The improved API round thread in this joint is an improvement on the basis of the API standard round thread, and retains the advantages of mature API standard round thread technology, simple processing and measurement, high processing efficiency, low cost and convenient maintenance. At the same time, it avoids the disadvantage that the diameter of the API threaded coupling becomes larger.

Further, the API round thread is improved on the geometric structure of the API round thread. There is a gap between the first tooth top and the second tooth bottom after the API round screw is screwed up, and this gap becomes the leakage channel of the fluid.

Further, the improved API round thread in the joint fills the leakage channel of the API standard round thread. After the diameter is expanded, the improved API round thread tooth top and tooth bottom form a metal-to-metal sealing structure, which has the advantages of a metal-to-metal sealing structure. , which improves the sealing performance of the connection.

Further, the hook-shaped internal and external threads of the negative angle in the joint are tightly engaged, which can eliminate stress concentration, and has strong connection strength and high anti-slipping ability.

Further, the negative angle torque shoulder in the joint can not only enhance the anti-torsion ability of the joint, but also play an auxiliary sealing role. During the expansion process, the inner pipe wall will not be uneven due to the rebound deformation of the end of the male thread. Keep the structure reliable.

Description of drawings

Figure 1 is a schematic structural diagram of a common expansion casing joint.

Figure 2 is a schematic view of a single lateral cross-sectional view of a joint structure suitable for an expansion casing.

Figure 3 is a schematic transverse cross-sectional view of a male threaded joint of a joint structure suitable for expansion sleeves.

Fig. 4 is an enlarged cross-sectional view of part A in Fig. 3 of the present invention.

Fig. 5 is an enlarged cross-sectional view of part B in Fig. 4 of the present invention.

Fig. 6 is an enlarged cross-sectional view of part C in Fig. 4 of the present invention.

Figure 7 is an API standard thread drawing.

In the figure, 1. Male threaded joint, 2. Female threaded joint, 3. Seal structure, 4. Barb thread, 5. API round thread, 6. Negative angle torque shoulder, 7. Seal groove, 8. Seal surface , 9. Sealing body, 10. Barb thread hook surface, 11. Barb thread hook tip, 12. Barb thread guide surface, 13. API round thread top, 14. API round thread bottom, 15 .API round thread flank, 16. Seal ring, 17. Torque shoulder.

The above technical features are described with the male threaded joint as the main body. In order to distinguish the specific description, "first" represents the feature on the male threaded joint, and "second" represents the feature on the female threaded joint.

Detailed ways

In order to make those skilled in the art better understand the technical solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described The embodiments are only some of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without creative work shall fall within the protection scope of the present invention.

As shown in Fig. 2 to Fig. 3 , the present invention is an expansion casing joint that improves the liquid sealing performance. The joint structure suitable for expansion casing adopts a direct-connected thread structure, and is composed of a male threaded joint 1 and a female threaded joint 2 , the wall thickness of the male threaded joint 1 is slightly larger than the wall thickness of the female threaded joint 2; the male threaded joint 1 is sequentially provided with negative angle torque shoulder 6, API round thread 5, sealing groove 7 and barb thread 4 from the end inward; The female threaded joint 2 is provided with a barb thread, a sealing surface, an API round thread and a negative angle torque shoulder at a position corresponding to the male threaded joint; the joint has a triple sealing structure in total, wherein the improved API round thread is the main metal seal , the negative angle torque shoulder is an auxiliary metal seal, and the seal in the seal groove is an elastic seal.

Among them, the wall thickness of the male thread joint is slightly larger than the wall thickness of the female thread.

As a preferred embodiment, the barb thread of the threaded joint is a single hook thread with a negative angle, the bearing surface angle is -15°～-20°, the thread taper is 1:20～1:25, and the thread The hook tip of the barb thread is an arc surface, and the declination angle of the thread guide surface is 10° to 25°; the hook-shaped inner and outer threads with a negative angle are tightly engaged, which can eliminate stress concentration and mainly play a connection role.

As a preferred embodiment, the API round thread has improved the geometric structure of the API round thread. The traditional API round thread has a gap between the tooth crest and the tooth bottom after screwing up, and this gap becomes the leakage channel of the fluid. , can not effectively carry out liquid sealing.

The principle of the present invention is:

(1) The improved API round thread of the present invention increases the tooth height of the male and female threads, and the increase range is about 0.076mm to 0.13mm. After the tooth height is increased, the tooth top and the tooth bottom of the male and female threads are crossed after the joint is buckled. The positive contact fills the gap between the tooth top and the tooth bottom of the API round thread, and eliminates the leakage channel of the API round thread;

(2) According to the improved API round thread structure of the present invention, when the casing expands, the male thread squeezes the female thread from the inside to the outside. At the same time, since the wall thickness of the female threaded joint is smaller than the wall thickness of the male threaded joint, the axial shrinkage of the female thread If it is larger than the male thread, the contact between the thread surfaces of the male and female threads is tighter, the contact stress is further increased, and the sealing effect is further achieved.

There are three schemes for the sealing body between the sealing groove of the male threaded joint and the metal sealing surface of the female threaded joint: elastic sealing ring, soft metal or thread grease, just choose one.

The elastic sealing ring/soft metal is fixed in the sealing groove of the male threaded joint. It adopts a rectangular cross-section, and the height is flush with the thread tops on both sides, which does not affect the installation. Squeeze the elastic sealing ring/soft metal so that it continues to extrude the sealing surface of the female threaded joint to play an auxiliary sealing role; the thread grease fills the gap between the two sections of the female threaded joint with different thread profiles, and the casing expands. When the diameter is increased, the male threaded joint is extruded first, and the thread grease is extruded outward to fill the gap of the third sealing part, which plays the role of auxiliary sealing.

The negative-angle torque shoulder at the end of the male threaded joint is in interference contact with the negative-angle torque shoulder at the inner end of the female threaded joint when the casing expands to form a metal seal, which plays an auxiliary sealing role, and its angle is - 20°～﹣25°.

Example

Taking a joint structure suitable for expansion casing as an example, the present invention will be further described in detail.

Referring to Figure 2, the joint structure suitable for the expansion casing is mainly composed of a male threaded joint 1 and a female threaded joint 2.

Referring to FIG. 3 , the expansion sleeve male threaded joint 1 is, from the outside, a negative angle torque shoulder 6 , an API round thread 5 , a sealing groove 7 and a barb thread 4 .

Referring to Fig. 2, the negative angle torque shoulder 6 of the male threaded joint 1 cooperates with the negative angle torque shoulder 6 of the inner end of the female threaded joint 2, and the interference contacts when the diameter is expanded, which plays the role of the first auxiliary sealing.

Referring to Figures 2 and 6, the improved API round thread 5 of the male threaded joint 1 is matched with the improved API round thread 5 of the female threaded joint 2. When the diameter is expanded, the tooth top 13 and tooth bottom 14 of the male and female threaded joints form metal to metal The interference fit of the sealing structure produces close contact on the flanks 15 of the internal and external threads. The whole section of the improved API round thread 5 plays the role of the second seal and is also the main seal.

Referring to Figure 4, the sealing structure 3 consists of a sealing groove 7, a sealing surface 8 and a sealing body 9. The sealing body 9 has three schemes: elastic sealing ring, soft metal or thread grease, just choose one. When the diameter is expanded, the sealing groove 7 is subjected to the outward pressing of the sealing body 9, and the sealing body 9 presses the sealing surface 8 to form a seal and play a third sealing role.

5, the off-angle of the barb-shaped thread hook surface 10 of the barb-shaped thread 4 is -18°, the barb-shaped thread hook tip 11 adopts an arc surface, and the off-angle of the barb-shaped thread guide surface 12 is 20°.

Referring to Figure 6, Figure 7 and Figure 1, the thread profile angle of the improved API round thread 5 is 60°, which is the same as that of the API standard round thread. The improved API round thread fills the gap of the API standard round thread. leak channel.

The technical features of the above embodiments can be combined arbitrarily. In order to make the description simple, all possible combinations of the technical features in the above embodiments are not described. However, as long as there is no contradiction in the combination of these technical features It is considered to be the range described in this specification.

The above examples only represent several embodiments of the present invention, and the descriptions thereof are more specific and detailed, but should not be construed as a limitation on the scope of the invention patent. It should be pointed out that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can also be made, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention should be subject to the appended claims.

It should be understood that the above description is for purposes of illustration and not limitation. From reading the above description, many embodiments and many applications beyond the examples provided will be apparent to those skilled in the art. The scope of the present teachings should, therefore, be determined not with reference to the above description, but should instead be determined with reference to the preceding claims, along with the full scope of equivalents to which such claims are entitled. The disclosures of all articles and references, including patent applications and publications, are incorporated herein by reference for the purpose of being comprehensive. The omission of any aspect of the subject matter disclosed herein in the preceding claims is not intended to disclaim such subject matter, nor should the applicant be considered as not considering such subject matter as part of the disclosed subject matter.

Claims (10)

1. an expansion casing joint improving liquid sealing performance, is characterized in that, comprises male threaded joint and female threaded joint; The male threaded joint is sequentially provided with a first negative angle torque shoulder, a first API round thread and a first barb thread from the end outward, and the female threaded joint is sequentially provided with the a second negative angle torque shoulder, a second API round thread and a second barb thread that are matched with the male threaded joint; an elastic sealing structure is arranged between the first API round thread and the first barb thread; The first API round thread and the second API round thread are in interference fit. 2 . The expansion casing joint according to claim 1 , wherein the wall thickness of the male threaded joint is greater than that of the female threaded joint. 3 . 3 . The expansion casing joint for improving liquid sealing performance according to claim 1 , wherein the circular thread structure comprises a tooth crest, a tooth bottom and a tooth flank connected in sequence, and the first tooth of the male threaded joint is 3 . The top and the second tooth bottom of the female threaded joint form an interference fit of the metal-to-metal sealing structure, and produce close contact on the flank of the tooth. 4. The expansion casing joint for improving liquid sealing performance according to claim 1, wherein the elastic sealing structure comprises a sealing groove, a sealing surface and a sealing body, and the sealing groove is filled and the sealing body is pressed outward, The sealing body presses the sealing surface to form a seal. 5 . The expansion casing joint with improved liquid sealing performance according to claim 4 , wherein the sealing groove is provided on the male threaded joint, and the sealing surface is provided on the female threaded joint. 6 . 6 . The expansion casing joint for improving liquid sealing performance according to claim 4 , wherein the sealing body is an elastic sealing ring, soft metal or thread grease. 7 . 7. The expansion casing joint for improving liquid sealing performance according to claim 1, wherein the barb thread is a single hook thread with a negative angle, comprising barb thread hook surfaces connected in sequence, Barbed thread tip and barbed thread guide. 8. The expansion casing joint for improving liquid sealing performance according to claim 7, wherein the bearing surface angle of the barb-shaped thread hook surface is -15°～-20°, and the thread taper is 1:( 20～25), the hook tip of the barb thread is an arc surface, and the declination angle of the guide surface of the barb thread is 10°～25°. 9 . The expansion casing joint according to claim 8 , wherein the bearing surface angle of the barb-shaped thread hook surface is -18°, and the off-angle of the barb-shaped thread guide surface is 9 . 20°. 10 . The expansion casing joint for improving liquid sealing performance according to claim 1 , wherein the first negative angle torque shoulder of the male threaded joint is in interference with the second negative angle torque shoulder of the female threaded joint. 11 . Contact; the angle of the first negative angle torque shoulder is -20°～-25°.

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