A heat-insulated and backflow-proof oil casing

Abstract

This utility model discloses a heat-insulated anti-backflow oil casing, relating to the field of petroleum equipment technology. It features good sealing performance during connection, ensuring the effectiveness of the anti-backflow system for the entire circuit. It includes an inner tube and an outer tube, with a vacuum heat-insulating cavity formed between them. An insulation layer is provided within the heat-insulating cavity. The left side of the outer tube contracts inward to form a left connecting section, and the right end of the inner tube expands outward to form a right connecting section. An external sealing structure is provided on the left connecting section, and an internal sealing structure corresponding to the external sealing structure is provided on the right connecting section. A check valve is provided on the side of the inner tube closest to the internal sealing structure.

Description

Technical Field

[0001] This utility model relates to the field of petroleum equipment technology, specifically to a heat-insulated and backflow-preventing oil casing. Background Technology

[0002] In the process of extracting heavy oil through steam injection or injection of other hot fluids, heat is easily lost. Therefore, insulated tubing is often used to reduce heat loss. Insulated tubing strings are the most commonly used tubing strings for steam injection in heavy oil thermal recovery processes. Insulated tubing consists of two parts: insulated tubing and couplings. Several insulated tubings are mainly connected by couplings. In the oilfield development field, tubing needs to withstand high temperature, high pressure, and corrosive media environments for a long time. Therefore, tubing needs to have excellent heat insulation, corrosion resistance, and backflow prevention performance.

[0003] For example, Chinese patent CN219472037U discloses a special threaded oil casing with high heat insulation performance, including a casing body and a coupling used in conjunction with the casing body. The casing body includes an outer layer tube, a middle layer tube, and an inner layer tube that are fixedly sleeved from the outside to the inside. The outer layer tube and the middle layer tube form a first sealed heat insulation cavity, and the middle layer tube and the inner layer tube form a second sealed heat insulation cavity. The second sealed heat insulation cavity is filled with heat insulation material, and the first sealed heat insulation cavity is a vacuum cavity. An annular heat insulation block is provided in the middle part of the inner side of the coupling. The oil casing includes a casing body and a coupling, wherein the coupling is provided with a heat insulation block. The inner layer tube in the casing body only contacts the heat insulation block, while the middle layer tube and the outer layer tube are insulated by the sealed heat insulation cavity, thereby greatly reducing heat loss.

[0004] In this patent, in order to ensure thermal insulation performance, an outer layer pipe, a middle layer pipe, and an inner layer pipe of the casing are set up. The structure is complex and the connection is made by ordinary threaded connection. It relies on only a single sealing surface and is prone to leakage under thermal stress cycle, which can lead to the mutual flow of annular fluid or the backflow of external medium. At the same time, it lacks a passive anti-backflow design, which can easily cause well control risks when the main valve fails. Utility Model Content

[0005] The technical problem to be solved by this utility model is to overcome the defects of the existing technology and provide a heat-insulating anti-backflow oil sleeve with good sealing performance during connection, which can ensure the effectiveness of the anti-backflow system of the entire circuit.

[0006] To solve the above-mentioned technical problems, the technical solution of this utility model is: a heat-insulating and anti-backflow oil casing, comprising an inner tube and an outer tube, wherein a vacuum heat-insulating cavity is formed between the inner tube and the outer tube, and a heat-insulating layer is provided in the heat-insulating cavity; the left side of the outer tube contracts inward to form a left connecting section, and the right end of the inner tube expands outward to form a right connecting section; an outer sealing structure is formed on the left connecting section, and an inner sealing structure corresponding to the outer sealing structure is formed on the right connecting section; a check valve is provided on the side of the inner tube near the inner sealing structure.

[0007] Furthermore, the external sealing structure includes a first external sealing shoulder, an external thread section, and a second external sealing shoulder connected in sequence. The first external sealing shoulder includes a first external sealing plane disposed at the end of the outer tube and a first external sealing inclined surface connected thereto. The other end of the first external sealing inclined surface is connected to the external thread section. The second external sealing shoulder includes an external sealing arc surface connected to the external thread section, a second external sealing inclined surface, and a second external sealing plane. The two ends of the second external sealing inclined surface are respectively connected to the external sealing arc surface and the second external sealing plane.

[0008] Furthermore, an annular groove is formed on the second outer sealing inclined surface, and an annular sealing gasket is fixedly installed in the annular groove.

[0009] Further, the inner sealing structure includes a first inner sealing shoulder, an internal thread segment, and a second inner sealing shoulder that are corresponding to and sequentially connected to the outer sealing structure. The first inner sealing shoulder includes a first inner sealing plane corresponding to the first outer sealing plane and a first inner sealing slope corresponding to the first outer sealing slope. The first inner sealing plane and the first inner sealing slope are connected. The other side of the first inner sealing slope is connected to the internal thread segment. The second inner sealing shoulder includes an inner sealing arc surface corresponding to the outer sealing arc surface, a second inner sealing slope corresponding to the second outer sealing slope, and a second inner sealing plane corresponding to the second outer sealing plane. The two ends of the second inner sealing slope are respectively connected to the inner sealing arc surface and the second inner sealing plane. The other end of the inner sealing arc surface is connected to the internal thread segment. The second inner sealing plane is located at the end of the inner tube. A sealing groove corresponding to the annular sealing gasket is formed on the second inner sealing slope.

[0010] Furthermore, a sealing gasket is fixedly provided on the first inner sealing plane.

[0011] Furthermore, both the internal thread segment and the external thread segment have trapezoidal threads with an isosceles trapezoidal tooth profile and a tooth angle of 30°.

[0012] Furthermore, both the annular sealing gasket and the sealing washer are made of corrosion-resistant rubber.

[0013] Furthermore, a plurality of positioning blocks are fixedly provided on the inner wall of the outer tube along its circumference, and the outer wall of the inner tube abuts against the positioning blocks.

[0014] Furthermore, the right end of the inner tube extends outward to form a positioning boss, and the left end of the tube extends outward to form a positioning edge, the edge of which abuts against the side wall of the outer tube.

[0015] Furthermore, the insulation layer is an aerogel filled within the insulation cavity.

[0016] By adopting the above technical solution, this utility model has the following beneficial effects: the outer sealing structure and inner sealing structure of two adjacent oil casings cooperate to improve the sealing performance at the connection, effectively sealing the annulus and preventing unexpected fluid exchange and backflow between different annulus or between the annulus and the oil pipe. At the same time, the robust seal ensures that when the main channel is cut off, the fluid cannot find a bypass to backflow. Good sealing is the basis for implementing effective pressure control measures. The check valve is used to provide additional, passive unidirectional flow protection, further ensuring the effectiveness of the anti-backflow system of the entire circuit. The two complement each other and are indispensable. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of the heat-insulating and backflow-preventing oil casing of this utility model.

[0018] Reference numerals: 1. Outer tube; 2. Inner tube; 3. Insulation cavity; 4. Insulation layer; 5. Positioning block;

[0019] 6. External sealing structure; 7. Internal sealing structure; 8. Check valve; 21. Positioning boss; 22. Positioning edge;

[0020] 61. First outer sealing shoulder; 62. External thread section; 63. Second outer sealing shoulder; 611. First outer sealing plane;

[0021] 612. First outer sealing bevel; 631. Outer sealing arc surface; 632. Second outer sealing bevel;

[0022] 633. Second outer sealing plane; 634. Annular sealing gasket; 71. First inner sealing shoulder; 72. Internal thread section;

[0023] 73. Second inner sealing shoulder; 711. First inner sealing plane; 712. First inner sealing slope;

[0024] 713. Sealing gasket; 731. Inner sealing arc surface; 732. Second inner sealing bevel surface; 733. Second inner sealing plane;

[0025] 734. Sealing groove. Detailed Implementation

[0026] To make the contents of this utility model easier to understand, the present utility model will be further described in detail below with reference to specific embodiments and accompanying drawings.

[0027] like Figure 1 As shown, in this embodiment, a heat-insulating and anti-backflow oil casing is provided, including an inner tube 2 and an outer tube 1. A vacuum heat-insulating cavity 3 is formed between the inner tube 2 and the outer tube 1. A heat-insulating layer 4 is provided in the heat-insulating cavity 3. The left side of the outer tube 1 contracts inward to form a left connecting section, and the right end of the inner tube 2 expands outward to form a right connecting section. The left connecting sections and right connecting sections of two adjacent oil casings cooperate to connect the oil casings. An outer sealing structure 6 is formed on the left connecting section, and an inner sealing structure 7 corresponding to the outer sealing structure 6 is formed on the right connecting section.

[0028] In this embodiment, the outer sealing structure 6 includes a first outer sealing shoulder 61, an external thread section 62, and a second outer sealing shoulder 63 connected sequentially on the outer tube 1. The first outer sealing shoulder 61 includes a first outer sealing plane 611 disposed at the end of the outer tube 1 and a first outer sealing inclined surface 612 connected thereto. The other end of the first outer sealing inclined surface 612 is connected to the external thread section 62. The second outer sealing shoulder 63 includes an outer sealing arc surface 631 connected to the external thread section 62, a second outer sealing inclined surface 632, and a second outer sealing plane 633. An annular groove is formed on the second outer sealing inclined surface 632, and an annular sealing gasket 634 is fixedly disposed in the annular groove. The two ends of the second outer sealing inclined surface 632 are respectively connected to the outer sealing arc surface 631 and the second outer sealing plane 633.

[0029] In this embodiment, the inner sealing structure 7 includes a first inner sealing shoulder 71, an internal thread section, and a second inner sealing shoulder 73, which are disposed on the inner tube 2 and are corresponding to and sequentially connected to the outer sealing structure 6. The first inner sealing shoulder 71 includes a first inner sealing plane 711 corresponding to the first outer sealing plane 611 and a first inner sealing slope 712 corresponding to the first outer sealing slope 612. A sealing gasket 713 is fixedly disposed on the first inner sealing plane 711, and the first inner sealing plane 711 and the first inner sealing slope 712 are connected. The other side of the first inner sealing slope 712 is connected to the internal thread section. The second inner sealing shoulder 73 includes an inner sealing arc surface 731 corresponding to the outer sealing arc surface 631, a second inner sealing inclined surface 732 corresponding to the second outer sealing inclined surface 632, and a second inner sealing plane 733 corresponding to the second outer sealing plane 633. The two ends of the second inner sealing inclined surface 732 are respectively connected to the inner sealing arc surface 731 and the second inner sealing plane 733. The other end of the inner sealing arc surface 731 is connected to the internal thread section. The second inner sealing plane 733 is located at the end of the inner tube 2. A sealing groove 734 corresponding to the annular sealing gasket 634 is provided on the second inner sealing inclined surface 732.

[0030] In this embodiment, both the annular sealing gasket 634 and the sealing washer 713 are made of corrosion-resistant rubber.

[0031] In this embodiment, both the internal thread segment and the external thread segment 62 are trapezoidal threads with an isosceles trapezoidal tooth profile and a tooth profile angle of 30°. The internal and external threads are tightly fitted with a tapered surface, making them less prone to loosening. The 30° trapezoidal thread has a thicker and stronger pitch diameter than ordinary 60° or 55° threads. It is more wear-resistant, has better strength, adjustable clearance, and better process performance than other threads. In this solution, the length of the internal thread segment and the external thread segment 62 is 200mm-220mm. Compared with the traditional process, extending the thread segment and connecting with only one thread segment can improve the connection strength.

[0032] In this embodiment, the insulation layer 4 is the insulation material filled in the insulation cavity 3. The insulation material can be rigid polyurethane foam, rock wool, glass wool, calcium silicate, or flexible foam rubber and plastic, aerogel, etc. The insulation material used in this solution is aerogel. Aerogel has a low thermal conductivity, good heat preservation performance, and long service life.

[0033] In this embodiment, multiple positioning blocks 5 are fixedly provided on the inner wall of the outer tube 1 along its circumference. During installation, the inner tube 2 is placed in the outer tube 1, and the outer wall of the inner tube 2 abuts against the positioning blocks 5, so that the inner tube 2 can always be centered and coaxial with the outer tube 1, thereby allowing the heat insulation material to be evenly filled between the outer tube 1 and the inner tube 2.

[0034] In this embodiment, the right end of the inner tube 2 extends outward to form a positioning boss 21. A certain gap is left between the end of the outer tube 1 and the positioning boss 21 of the inner tube 2 to fill the gap with heat insulation material and vacuum treatment. The left end of the inner tube 2 extends outward to form a positioning edge 22. The edge of the positioning edge 22 abuts against the side wall of the outer tube 1. The connection between the outer tube 1 and the inner tube 2 is fixedly connected by welding.

[0035] In this embodiment, a check valve 8 is provided on the side of the inner tube 2 near the inner sealing structure 7. The outer sealing structure 6 and the inner sealing structure 7 work together to improve the sealing performance at the connection, effectively sealing the annulus and preventing unexpected fluid exchange and backflow between different annulus or between the annulus and the oil pipe. At the same time, the robust seal ensures that when the main channel is cut off, the fluid cannot find a bypass to backflow. Good sealing is the basis for implementing effective pressure control measures. The check valve 8 is used to provide additional, passive unidirectional flow protection, further ensuring the effectiveness of the anti-backflow system of the entire circuit. The two complement each other and are indispensable.

[0036] The present invention provides a high-strength direct-connection threaded heat-insulating oil pipe, the processing and connection method and advantages of which are as follows: the inner tube 2 is placed inside the outer tube 1, the outer wall of the inner tube 2 abuts against the positioning block 5, and the edge of the positioning edge 22 of the inner tube 2 abuts against the side wall of the outer tube 1. One end of the positioning edge 22 of the inner tube 2 is welded and fixed to the outer tube 1. Heat-insulating material is filled between the outer tube 1 and the inner tube 2 through the gap between the other end of the outer tube 1 and the positioning boss 21 of the inner tube 2, and a vacuum treatment is performed. After the treatment is completed, the inner tube... The positioning boss 21 of the 2 is welded to the end of the outer tube 1; according to the usage requirements, a certain number of oil casings are connected together. Specifically, the left connecting section of the first adjacent oil casing is matched with the right connecting section of the second oil casing to complete the connection of the oil casings. After the connection is completed, the first outer sealing plane 611 of the first oil casing abuts against the sealing gasket 713 of the second oil casing, so that the first outer sealing slope 612 of the first oil casing fits against the first inner sealing slope 712 of the second oil casing. The internal and external thread sections 62 of the casing and tubing are fitted together to complete the threaded connection. The outer sealing arc surface 631 of the first casing and tubing abuts against the inner sealing arc surface 731 of the second casing and tubing, so that the second outer sealing slope of the first casing and tubing fits against the second inner sealing slope 732 of the second casing and tubing. The annular sealing gasket 634 is inserted into the sealing groove 734. The second outer sealing plane 633 of the first casing and tubing abuts against the second inner sealing plane 733 of the second casing and tubing. The outer sealing structure 6 and the inner sealing structure 7 of the two adjacent casing and tubing work together to improve the sealing performance at the connection, effectively sealing the annulus and preventing unexpected fluid exchange and backflow between different annulus or between the annulus and the tubing. At the same time, the robust seal ensures that when the main channel is cut off, the fluid cannot find a bypass to backflow. Good sealing is the basis for implementing effective pressure control measures. The check valve 8 is used to provide additional, passive unidirectional flow protection, further ensuring the effectiveness of the anti-backflow system of the entire circuit. The two complement each other and are indispensable.

[0037] The above-described specific embodiments of the second inner sealing shoulder 73 further illustrate the technical problems, technical solutions, and beneficial effects of this utility model. It should be understood that the above descriptions are merely specific embodiments of this utility model and are not intended to limit this utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. A heat-insulating and backflow-preventing oil casing, characterized in that: It includes an inner tube (2) and an outer tube (1), and a vacuum insulation cavity (3) is formed between the inner tube (2) and the outer tube (1). An insulation layer (4) is provided in the insulation cavity (3). The left side of the outer tube (1) contracts inward to form a left connecting section, and the right end of the inner tube (2) expands outward to form a right connecting section. An outer sealing structure (6) is formed on the left connecting section, and an inner sealing structure (7) corresponding to the outer sealing structure (6) is formed on the right connecting section. A check valve (8) is provided on the side of the inner tube (2) near the inner sealing structure (7).

2. The heat-insulating and backflow-preventing oil casing according to claim 1, characterized in that: The external sealing structure (6) includes a first external sealing shoulder (61), an external thread section (62), and a second external sealing shoulder (63) connected in sequence. The first external sealing shoulder (61) includes a first external sealing plane (611) disposed at the end of the outer tube (1) and a first external sealing inclined surface (612) connected thereto. The other end of the first external sealing inclined surface (612) is connected to the external thread section (62). The second external sealing shoulder (63) includes an external sealing arc surface (631), a second external sealing inclined surface (632), and a second external sealing plane (633) connected to the external thread section (62). The two ends of the second external sealing inclined surface (632) are respectively connected to the external sealing arc surface (631) and the second external sealing plane (633).

3. The heat-insulating and backflow-preventing oil casing according to claim 2, characterized in that: An annular groove is provided on the second outer sealing inclined surface (632), and an annular sealing gasket (634) is fixedly provided in the annular groove.

4. The heat-insulating and backflow-preventing oil casing according to claim 3, characterized in that: The inner sealing structure (7) includes a first inner sealing shoulder (71), an internal thread segment, and a second inner sealing shoulder (73) that are corresponding to and sequentially connected to the outer sealing structure (6). The first inner sealing shoulder (71) includes a first inner sealing plane (711) corresponding to the first outer sealing plane (611) and a first inner sealing slope (712) corresponding to the first outer sealing slope (612). The first inner sealing plane (711) and the first inner sealing slope (712) are connected. The other side of the first inner sealing slope (712) is connected to the internal thread segment. The second inner sealing shoulder (73) includes a first inner sealing shoulder (711) corresponding to the outer sealing slope (612). The inner sealing arc surface (731) is corresponding to the second outer sealing inclined surface (632), the second inner sealing inclined surface (732) is corresponding to the second outer sealing plane (633), and the second inner sealing plane (733) is corresponding to the second outer sealing plane (633). The two ends of the second inner sealing inclined surface (732) are respectively connected to the inner sealing arc surface (731) and the second inner sealing plane (733). The other end of the inner sealing arc surface (731) is connected to the internal thread section. The second inner sealing plane (733) is located at the end of the inner tube (2). The second inner sealing inclined surface (732) is provided with a sealing groove (734) corresponding to the annular sealing gasket (634).

5. The heat-insulating and backflow-preventing oil casing according to claim 4, characterized in that: A sealing gasket (713) is fixedly provided on the first inner sealing plane (711).

6. The heat-insulating and backflow-preventing oil casing according to claim 4, characterized in that: Both the internal thread segment and the external thread segment (62) have trapezoidal threads with an isosceles trapezoidal tooth profile and a tooth profile angle of 30°.

7. The heat-insulating and backflow-preventing oil casing according to claim 5, characterized in that: Both the annular sealing gasket (634) and the sealing washer (713) are made of corrosion-resistant rubber.

8. The heat-insulating and backflow-preventing oil casing according to claim 1, characterized in that: Multiple positioning blocks (5) are fixedly provided on the inner wall of the outer tube (1) along its circumference, and the outer wall of the inner tube (2) abuts against the positioning blocks (5).

9. The heat-insulating and backflow-preventing oil casing according to claim 1, characterized in that: The right end of the inner tube (2) extends outward to form a positioning boss (21), and the left end of the tube extends outward to form a positioning edge (22). The edge of the positioning edge (22) abuts against the side wall of the outer tube (1).

10. The heat-insulating and backflow-preventing oil casing according to claim 1, characterized in that: The heat insulation layer (4) is an aerogel filled in the heat insulation cavity (3).

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