Integral dual tubing wellhead and Christmas tree assembly

Abstract

The application relates to a whole double-tube wellhead and Christmas tree device, which comprises a lower wellhead, a bearing step arranged on the inner wall of the lower wellhead, a bearing ring abutting against the bearing step, a locking seat abutting against the bearing ring, the outer side of the locking seat being threadedly connected with the lower wellhead, the inner side of the locking seat being threadedly connected with an upper whole wellhead, the inner wall top of the locking seat being provided with an inner plug-in part, the outer wall top of the locking seat being provided with an outer plug-in part, the top of the lower wellhead being provided with a first plug-in groove matched with the bottom profile of the outer plug-in part, the bottom outer wall of the upper whole wellhead being provided with a second plug-in groove matched with the top profile of the inner plug-in part, and the first plug-in groove and the outer plug-in part bottom abutting part and the second plug-in groove and the inner plug-in part top abutting part being respectively provided with a first sealing ring. The application is favorable for solving the problem that the cooperation degree of the thread connection action and the sealing effect is poor in some devices.

Description

Technical Field

[0001] This invention relates to the field of oil and gas development equipment, and in particular to an integrated dual-tube wellhead and wellhead system. Background Technology

[0002] Oil and gas wellhead equipment, also known as completion wellhead equipment, mainly includes the wellhead (tree), tubing head, casing head, and related accessories. It is used for suspension, support, control, and adjustment of oil and gas production equipment. As crucial equipment in oil and gas production, its performance directly affects the safe and efficient production of oil and gas wells. With the continuous development of the petroleum industry, higher demands are placed on the reliability and controllability of wellhead equipment and valves, prompting continuous improvement and development of wellhead equipment.

[0003] A search revealed that patent application number CN202310231059.0 discloses an integrated dual-tube wellhead and Christmas tree device, comprising a lower wellhead, an upper integrated wellhead, a first casing hanger, a second casing hanger, a sealing device, a dual tubing hanger, and an integrated dual-tube Christmas tree. A first bearing step is provided on the inner wall of the lower wellhead for installing the first casing hanger. The upper integrated wellhead is sealed to the lower wellhead. A second bearing step and a third bearing step are respectively provided inside the upper integrated wellhead. The second bearing step is used to install the second casing hanger. The sealing device is installed on the second casing hanger and locked inside the upper integrated wellhead by a first locking mechanism. The third bearing step is used to install the dual tubing hanger, which is locked inside the upper integrated wellhead by a second locking mechanism. The integrated dual-tube Christmas tree connects two tubings through the dual tubing hanger.

[0004] In this technical solution, a bearing ring is threaded to the outer side of the lower end of the upper integral wellhead, and a fourth bearing step is provided on the inner wall of the upper end of the lower wellhead for installing the bearing ring. A locking seat is threaded to the upper end of the lower wellhead, and the lower end of the locking seat presses the bearing ring onto the fourth bearing step. The inner and outer walls of the locking seat are sealed to the upper integral wellhead and the lower wellhead through inner and outer sealing rings, respectively. Because the locking seat has threaded connections both inside and outside, and the sealing effect is achieved directly between its inner and outer walls and the connecting components through sealing rings, the tightening action of the threads is accompanied by relative axial displacement between the locking seat and the connecting components. This can cause the sealing ring in the connection gap to easily shift and slide out of the sealing groove. This not only increases the tightening resistance of the threaded connection, making tightening difficult, but also deviates from the expected sealing effect, significantly affecting the sealing performance. Summary of the Invention

[0005] This invention provides an integrated dual-tube wellhead and Christmas tree device, which helps to solve the problem of poor matching between the threaded connection action and sealing effect in some existing devices.

[0006] This invention is implemented as follows:

[0007] An integrated dual-tube wellhead and Christmas tree assembly includes a lower wellhead, with a surface casing sealed to the bottom of the lower wellhead. A bearing step is provided on the inner wall of the lower wellhead, a bearing ring abuts against the bearing step, and a locking seat abuts against the bearing ring. The outer side of the locking seat is threaded to the lower wellhead, and the inner side of the locking seat is threaded to an upper integrated wellhead. Two tubings are connected inside the upper integrated wellhead. An internal insertion portion is provided at the connection between the top of the inner wall of the locking seat and the upper integrated wellhead. The top of the outer wall of the locking seat... An external insertion part is provided at the connection with the lower wellhead. The longitudinal section of the internal insertion part is narrow at the top and wide at the bottom. The longitudinal section of the external insertion part is wide at the top and narrow at the bottom. The top of the lower wellhead is provided with a first insertion groove that matches the bottom contour of the external insertion part. The outer wall of the bottom of the upper integral wellhead is provided with a second insertion groove that matches the top contour of the internal insertion part. A first sealing ring is respectively provided at the abutment of the first insertion groove with the bottom of the external insertion part and at the abutment of the second insertion groove with the top of the internal insertion part.

[0008] Based on the above technical solution, the inner end face of the inner insertion part and the internal thread end face of the locking seat are located on the same longitudinal plane.

[0009] Based on the above technical solution, the second insertion groove is provided with a flange portion that is narrow at the bottom and wide at the top on the radial outer side, and the inner sidewall of the flange portion can form a beveled fitting structure with the outer sidewall of the inner insertion portion after locking.

[0010] Based on the above technical solution, the inner wall of the first insertion slot near the locking seat body and the inner wall of the locked outer insertion part form a sloped fitting structure.

[0011] Based on the above technical solution, the first insertion slot and the bottom abutment of the outer insertion part, and the second insertion slot and the top abutment of the inner insertion part are located at the same horizontal position.

[0012] Based on the above technical solution, a pre-fixed connection structure is provided between the first sealing ring and the inner or outer insertion part.

[0013] Based on the above technical solution, the pre-fixed connection structure is adhesive tape.

[0014] Based on the above technical solution, the first sealing ring has a skeleton inside, the skeleton includes a rigid core with a circular structure, a number of radially extending ribs are evenly distributed on the outer periphery of the rigid core, and an elastic wrapping layer is provided on the outer periphery of the skeleton.

[0015] Based on the above technical solution, the elastic wrapping layer is provided with several hollowed-out parts.

[0016] Based on the above technical solution, a second sealing ring is provided at the inclined surface fitting structure.

[0017] Compared with the prior art, the present invention has at least the following advantages:

[0018] This invention effectively solves the problem of poor matching between threaded connection action and sealing effect in existing technologies through a unique plug-in structure and beveled fitting design. The upper-narrow and lower-wide structure of the inner and outer plug-in parts, along with their matching with the corresponding plug-in groove, makes the installation position of the first sealing ring more reliable and stable, reducing the possibility of sealing ring displacement. At the same time, the inner and outer end faces of the locking seat maintain a longitudinal end face in the threaded structure area, and the separation layout from the installation position of the first sealing ring effectively avoids the mutual interference between the threaded connection action and the sealing ring extrusion deformation action, further improving sealing performance and ensuring the safety and reliability of the oil and gas extraction process. Attached Figure Description

[0019] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained from these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the integrated double-tube wellhead and Christmas tree in Example 1;

[0021] Figure 2 for Figure 1 A magnified view of part A in the image;

[0022] Figure 3 for Figure 2 A partial schematic diagram of the installation structure of the first sealing ring;

[0023] Figure 4 This is a three-dimensional structural diagram of the first sealing ring in Example 2 with the bottom facing upwards;

[0024] Figure 5 This is a partial schematic diagram of the installation structure of the first sealing ring in Example 2;

[0025] Figure 6 This is a cross-sectional view of the first sealing ring in Example 3;

[0026] Figure 7 This is a cross-sectional view of the first sealing ring in Example 4;

[0027] Figure 8 This is a partial schematic diagram of the installation structure of the first sealing ring in Example 5.

[0028] The diagram is labeled as follows: 1. Lower wellhead; 101. First insertion groove; 2. Upper integral wellhead; 201. Flange; 202. Second insertion groove; 203. Second sealing groove; 3. First casing hanger; 4. Second casing hanger; 5. Sealing device; 6. Dual tubing hanger; 7. Integral dual tubing Christmas tree; 8. Surface casing; 9. Surface casing hanger; 10. Bearing step; 11. Bearing ring; 12. Locking seat; 1201. Inner insertion part; 1202. Outer insertion part; 1203. First sealing groove; 13. First sealing ring; 1301. Adhesive tape; 1302. Skeleton; 1303. Hollowed-out part; 14. Second sealing ring. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention.

[0030] In the description of this invention, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0031] It should be noted that when an element is referred to as being "fixed to" another element, it can be directly on the other element or there may be an intervening element. When an element is referred to as being "connected to" another element, it can be directly connected to the element or there may be an intervening element. The terms "vertical," "horizontal," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only possible implementation.

[0032] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0033] Example 1: This example discloses an integrated dual-tube wellhead and Christmas tree device to effectively solve the problem of poor matching between threaded connection action and sealing effect in some existing devices, improve the sealing performance and connection stability of the wellhead device, and ensure the safety and efficiency of the oil and gas extraction process.

[0034] Combination Figure 1 As shown, the integrated dual-tube wellhead and Christmas tree device in this embodiment includes a lower wellhead 1, with a sealed connection at the bottom of the lower wellhead 1 to the surface casing 8, providing basic support and connection to the formation for the entire device. A first casing hanger 3 is connected inside the lower wellhead 1, used to suspend the intermediate casing. The lower end of the upper integrated wellhead 2 is sealed to the upper end of the lower wellhead 1, sealing the annulus between the surface casing 8 and the intermediate casing. A second casing hanger 4 is installed inside the upper integrated wellhead 2, used to suspend and seal the inner casing. A sealing device 5 is installed on the second casing hanger 4, used to seal the annulus between the intermediate casing and the inner casing. A dual tubing hanger 6 is also installed on the upper integrated wellhead 2, used to suspend and seal the two internal tubings respectively, sealing the space between the upper integrated wellhead 2 and the two internal tubings. The integrated dual-tube wellhead 7 is connected to the upper end of the upper integrated wellhead 2. The dual channels in the integrated dual-tube wellhead 7 are connected to two tubings respectively through the dual tubing hangers 6. The surface casing hanger 9 has an inverted slip structure. The slips are fixedly connected to the bottom of the lower wellhead 1 by bolts, locking and suspending the surface casing 8. It should be noted that the main structure of the above-mentioned integrated dual-tube wellhead and wellhead device is prior art. Its specific structure and working principle can be found in the content disclosed in the existing patent CN202310231059.0, and will not be repeated here. Those skilled in the art can select and implement from the prior art according to the actual operation.

[0035] Combination Figure 2 and Figure 3 As shown, a bearing step 10 is provided on the inner wall of the lower wellhead 1, and a bearing ring 11 abuts against the bearing step 10. The bearing ring 11 serves to transfer and distribute the load. A locking seat 12 abuts against the bearing ring 11, and the outer side of the locking seat 12 is threadedly connected to the lower wellhead 1, achieving initial fixation between the locking seat 12 and the lower wellhead 1. The inner side of the locking seat 12 is threadedly connected to the upper integral wellhead 2, and two oil pipes are connected inside the upper integral wellhead 2 for oil and gas transportation.

[0036] To address the issues of sealing and connection stability, an inner insertion part 1201 is provided at the connection between the top of the inner wall of the locking seat 12 and the upper integral wellhead 2, and an outer insertion part 1202 is provided at the connection between the top of the outer wall of the locking seat 12 and the lower wellhead 1. The longitudinal section of the inner insertion part 1201 is narrower at the top and wider at the bottom, and the longitudinal section of the outer insertion part 1202 is wider at the top and narrower at the bottom. This structure offers unique advantages. The top of the lower wellhead 1 is provided with a first insertion groove 101 that matches the bottom contour of the outer insertion part 1202, and the outer wall at the bottom of the upper integral wellhead 2 is provided with a second insertion groove 202 that matches the top contour of the inner insertion part 1201. First sealing rings 13 are respectively clamped at the bottom abutting point of the first insertion groove 101 and the outer insertion part 1202, and at the top abutting point of the second insertion groove 202 and the inner insertion part 1201. In fact, the first sealing ring 13 is horizontally placed after installation. This is a separate layout from the longitudinal end face of the thread structure on the inner and outer walls of the locking seat 12. The two are not in a related longitudinal plane relationship. The longitudinal displacement during the thread locking process will not affect the longitudinal position of the first sealing ring 13. Therefore, unlike the traditional structure, there will be no longitudinal displacement, which would increase the locking resistance and reduce the sealing effect due to misalignment of the sealing position. That is, through this insertion structure and the setting of the sealing ring, the sealing performance of the connection part can be effectively improved.

[0037] like Figure 3 As shown, a recessed first sealing groove 1203 is provided at the top center of the first insertion groove 101, and a second sealing groove 203 is provided at the corresponding position on the top end face of the second insertion groove 202. Both the first sealing groove 1203 and the second sealing groove 203 are annular grooves with a semi-circular profile in longitudinal section, used to hold the upper and lower ends of the first sealing ring 13.

[0038] Furthermore, the inner end face of the inner insertion part 1201 and the internal thread end face of the locking seat 12 are located on the same longitudinal plane. This design makes the inner insertion part 1201 and the internal thread part of the locking seat 12 more structurally coordinated, and can better transmit force during installation and under stress. Its longitudinal displacement is smoother and more stable, avoiding stress concentration problems caused by structural mismatch, thereby improving the strength and stability of the entire connection part.

[0039] The second insertion groove 202 has a flange portion 201 that is narrower at the bottom and wider at the top on its radially outer side. The inner wall of the flange portion 201 can form a beveled fit structure with the outer wall of the locked inner insertion portion 1201. This beveled fit structure can generate a certain self-locking effect during the locking process. When the locking seat 12 is tightened to the upper integral wellhead 2 by threads, the beveled surfaces of the inner insertion portion 1201 and the flange portion 201 are pressed against each other, changing from a single longitudinal movement to a longitudinal and lateral limiting self-locking structure, making the connection tighter and less prone to loosening. At the same time, this structure can further enhance the sealing effect, because the beveled fit can better prevent oil and gas leakage.

[0040] The inner wall of the first insertion groove 101 near the main body of the locking seat 12 forms a beveled fit structure with the inner wall of the locked outer insertion part 1202. Similar to the above principle, this beveled fit structure can also improve the connection stability and sealing performance between the lower wellhead 1 and the locking seat 12. During the thread tightening process, the beveled surface of the outer insertion part 1202 and the first insertion groove 101 press against each other, enhancing the firmness of the connection and effectively preventing oil and gas leakage from the connection point.

[0041] In this embodiment, the abutment points of the first insertion groove 101 and the bottom of the outer insertion part 1202, and the abutment points of the second insertion groove 202 and the top of the inner insertion part 1201, are located at the same horizontal position. That is, the installation positions of the two first sealing rings 13 inside and outside the locking seat 12 are on the same horizontal plane. This design makes the force on the two sealing parts more uniform. During the thread tightening process, this helps to ensure that the two first sealing rings 13 inside and outside are subjected to longitudinal compression at a basically synchronous time and generate deformation resistance synchronously. When bearing internal pressure and external load, they can work together to improve the sealing reliability of the entire device. If the two sealing parts are not at the same horizontal position, it may lead to uneven force, with some sealing parts bearing excessive pressure, thereby affecting the sealing effect and service life. Furthermore, during the tightening process, if the compression deformation time of the two first sealing rings 13 is inconsistent, the resistance of a single first sealing ring 13 may change due to uncontrollable deformation, which may affect the stability of subsequent tightening actions.

[0042] Example 2: Based on Example 1, combined with Figure 4 and Figure 5 As shown, in this embodiment, a pre-fixed connection structure is provided between the first sealing ring 13 and the inner insertion part 1201 or the outer insertion part 1202. The function of the pre-fixed connection structure is to prevent the first sealing ring 13 from shifting during installation, ensuring that it can be accurately installed in the sealing position. In this invention, the pre-fixed connection structure uses adhesive tape 1301, which is placed at the bottom of the first sealing ring 13, so that it can always be firmly fixed in the first sealing groove 1203 before locking. The adhesive tape 1301 has a certain degree of adhesion, which can temporarily fix the first sealing ring 13 to the inner insertion part 1201 or the outer insertion part 1202. During the installation process, even if a certain vibration or displacement occurs, the first sealing ring 13 will not easily fall out of the predetermined position, thereby ensuring the accuracy and reliability of the sealing installation.

[0043] Example 3: Based on Example 1, combined with Figure 6As shown, in this embodiment, the first sealing ring 13 has a skeleton 1302 inside. The skeleton 1302 includes a rigid core with a circular ring structure. Several radially extending ribs are evenly distributed on the outer periphery of the rigid core. The rigid core and ribs are made of aluminum. An elastic wrapping layer made of rubber is provided around the skeleton 1302. The rigid core provides basic shape support for the first sealing ring 13, giving it a certain strength and rigidity, enabling it to withstand a certain amount of pressure without excessive deformation. The rib design further enhances the strength and stability of the skeleton 1302, while increasing the contact area with the elastic wrapping layer and improving the bonding force between the skeleton 1302 and the elastic wrapping layer. The elastic wrapping layer gives the first sealing ring 13 good elasticity and sealing performance, allowing it to elastically deform under pressure, filling the gaps in the connection area and achieving a good sealing effect.

[0044] Example 4: Based on Example 3, combined with Figure 7 As shown, in this embodiment, the elastic wrapping layer has several perforated portions 1303. The perforated portions 1303 have larger perforated areas closer to the outer side to improve their flexibility. The perforated portions 1303 have multiple functions. On the one hand, they can reduce the weight of the first sealing ring 13, reducing the load on the entire device; on the other hand, the perforated portions 1303 can deform when the sealing ring is under pressure, forming a buffer space, reducing stress concentration, and improving the pressure resistance and service life of the sealing ring. In addition, the perforated portions 1303 can also improve the elastic properties of the sealing ring to a certain extent, allowing it to recover its original shape more quickly when pressure changes, maintaining a good sealing effect.

[0045] Example 5: Based on Example 1, combined with Figure 7 As shown, in this embodiment, two second sealing rings 14 are clamped at the inclined surface fitting structure. Sealing grooves are also provided on the upper and lower sides of the second sealing rings 14 for limiting and fixing. It should be noted that the longitudinal profile of the sealing groove is not a semi-circular structure, but an eccentric circular profile. This is to improve its pre-fixing effect and prevent displacement caused by the inclined end face. The second sealing rings 14 further enhance the sealing performance of the inclined surface fitting area. In the inclined surface fitting structure, although the compression of the inclined surface can prevent oil and gas leakage to a certain extent, small gaps may still exist due to factors such as processing precision and installation errors. The second sealing rings 14 can fill these small gaps, forming a double sealing guarantee, greatly improving the sealing reliability of the entire device.

[0046] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An integral double-tube wellhead and Christmas tree device, comprising a lower wellhead (1), the bottom of which is sealed and connected to a surface casing, a bearing step (10) is provided on the inner wall of the lower wellhead (1), a bearing ring (11) abuts on the bearing step (10), a locking seat (12) abuts on the bearing ring (11), the outer side of the locking seat (12) is threadedly connected to the lower wellhead (1), and the inner side of the locking seat (12) is threadedly connected to an upper integral wellhead (2), the upper integral wellhead (2) having two tubing connected inside, characterized in that, The top of the inner wall of the locking seat (12) is provided with an inner insertion part (1201) at the connection between the top of the inner wall and the upper integral wellhead (2), and an outer insertion part (1202) is provided at the connection between the top of the outer wall of the locking seat (12) and the lower wellhead (1). The longitudinal section of the inner insertion part (1201) is narrow at the top and wide at the bottom, and the longitudinal section of the outer insertion part (1202) is wide at the top and narrow at the bottom. The top of the lower wellhead (1) is provided with an outer insertion part. The bottom contour of the inner plug part (1202) is adapted to the first plug groove (101), and the bottom outer wall of the upper integral wellhead (2) is provided with a second plug groove (202) adapted to the top contour of the inner plug part (1201). The first plug groove (101) and the bottom of the outer plug part (1202) and the second plug groove (202) and the top of the inner plug part (1201) are respectively provided with a first sealing ring (13). A pre-fixed connection structure is provided between the first sealing ring (13) and the inner insertion part (1201) or the outer insertion part (1202); the pre-fixed connection structure is adhesive tape (1301). The inner end face of the inner insertion part (1201) and the inner thread end face of the locking seat (12) are located on the same longitudinal plane; the second insertion groove (202) is provided with a flange part (201) that is narrow at the bottom and wide at the top on the radial outer side, and the inner wall of the flange part (201) can form a beveled fitting structure with the outer wall of the inner insertion part (1201) after locking.

2. The integrated dual-tube wellhead and Christmas tree device according to claim 1, characterized in that, The inner wall of the first insertion groove (101) near the main body of the locking seat (12) forms an inclined surface fitting structure with the inner wall of the locked outer insertion part (1202).

3. The integrated dual-tube wellhead and Christmas tree device according to claim 1, characterized in that, The bottom abutment of the first insertion slot (101) and the outer insertion part (1202), and the top abutment of the second insertion slot (202) and the inner insertion part (1201) are located at the same horizontal position.

4. The integrated dual-tube wellhead and Christmas tree device according to claim 1, characterized in that, The first sealing ring (13) has a skeleton (1302) inside. The skeleton (1302) includes a rigid core with a circular structure. Several radially extending ribs are evenly distributed on the outer periphery of the rigid core. An elastic wrapping layer is provided on the outer periphery of the skeleton (1302).

5. The integrated dual-tube wellhead and Christmas tree device according to claim 4, characterized in that, The elastic wrapping layer has several hollowed-out sections (1303).

6. An integrated dual-tube wellhead and Christmas tree device according to claim 1 or 2, characterized in that, A second sealing ring (14) is provided at the inclined surface fitting structure.

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