Multifunctional three-tube thermal recovery wellhead device for heavy oil horizontal well with electric heating assisted gravity drainage

Abstract

The present invention relates to the technical field of oil well exploitation, and provides a multifunctional three-tube thermal recovery wellhead device for electric heating assisted gravity drainage of heavy oil horizontal wells, comprising: an oil tree, and a tubing head and a casing head installed on the oil tree from top to bottom, the oil tree comprising a first four-way, one end of which is provided with a test channel and an electric heating channel, the oil tubing head comprising a second four-way, and a sealing device 1 is provided in the second four-way; the present invention provides a test channel and an electric heating channel, and respectively passes a test pipeline and an electric heating pipe into the oil tree from the test channel and the electric heating channel, thereby reducing installation and maintenance costs; the pressure difference between the oil pipe and the casing is monitored by a pressure sensor provided on the oil pipe and the casing, and when the pressure difference increases, a sealing ring 1 is squeezed outward, thereby increasing the friction between the sealing ring 1 and the oil pipe head, thereby increasing the sealing performance.

Description

Technical Field

[0001] The invention relates to the technical field of oil well exploitation, in particular to a multifunctional three-tube thermal recovery wellhead device for heavy oil horizontal well electric heating assisted gravity oil drainage. Background Art

[0002] Due to its high viscosity, heavy oil has extremely poor fluidity under conventional mining conditions, resulting in low mining efficiency. Traditional mining methods such as mechanical pumping and water injection are often ineffective and costly when dealing with heavy oil. Electric heating technology injects electrical energy into the heating element in the oil layer, and the resistance in the heating element generates heat to heat the oil layer, reduce the viscosity of the heavy oil, and thus improve its fluidity. This technology has been applied in many oil fields and has shown good mining results. At the same time, under the action of gravity, the heavy oil flows to the production well, and the casing and oil pipe are connected to the well through the three-tube thermal recovery wellhead device to achieve multiple functions such as oil production and testing.

[0003] Due to its versatility, the multifunctional three-tube thermal recovery wellhead device needs to design multiple auxiliary pipes (such as electric heating pipes and test pipes) to realize monitoring, testing and other functions. Most of the auxiliary pipes are installed at the tubing head at an angle, which reduces the difficulty of installing the auxiliary pipe in the main pipeline (such as it is difficult to ensure its sealing when the auxiliary pipe passes through the tubing hanger). However, the pipeline needs to be tilted during installation, which is easy to damage the pipeline. In the existing wellhead device, the sealing between the tubing and the casing is ensured by the sealing ring of the tubing hanger and the sealing ring on the casing head. However, long-term pressure changes may cause the sealing ring on the tubing hanger and the sealing ring on the casing head to loosen, and cause oil leakage. Summary of the invention

[0004] The invention provides a multifunctional three-tube thermal recovery wellhead device for heavy oil horizontal well electric heating assisted gravity oil drainage, which solves the problems existing in the background technology by strengthening the sealing performance between the oil pipe and the casing.

[0005] The technical solution of the present invention is as follows:

[0006] A multifunctional three-tube thermal recovery wellhead device for heavy oil horizontal well electric heating assisted gravity drainage, comprising: a Christmas tree, and a tubing head and a casing head installed on the Christmas tree from top to bottom;

[0007] The Christmas tree comprises a first four-way, a test channel and an electric heating channel are installed at one end of the first four-way, a main gate is installed at the other end of the first four-way, the test channel and the main gate are respectively located at the two ends of the first four-way, and the main gate is used to control the outflow of oil;

[0008] The tubing head comprises a second four-way pipe, a tubing hanger is installed in the second four-way pipe, a tubing is hung in the tubing hanger, one end of the tubing is connected to a connecting pipe, the connecting pipe is located in the Christmas tree, two fixing heads are arranged on the tubing hanger, the fixing heads fix and seal the pipes passing through the test channel and the electric heating channel, the tubing hanger is externally threaded with a plurality of sealing blocks, a sealing ring is arranged between every two sealing blocks, a sealing device is arranged in the second four-way pipe, the sealing device moves the sealing ring according to the pressure change, so that the sealing device always keeps close contact with the tubing head;

[0009] The casing head comprises a third four-way cross-piece, a casing hanger is installed in the third four-way cross-piece, casing is hung in the casing hanger, and a second sealing device is arranged in the third four-way cross-piece, and the second sealing device seals the casing and the tubing head.

[0010] Preferably, the first four-way bypass is respectively installed with a pressure monitoring valve 1 and a production valve through a pipeline, and a production pressure monitoring valve is installed on the production valve.

[0011] Preferably, an upper flange 1 is provided at the other end of the main gate, and the sealing device 1 includes a threaded rod and a fixed disk, the fixed disk is fixedly connected to the inner wall of the upper flange 1, the threaded rod is rotatably connected to the fixed disk and passes through the sealing block, a plurality of pressure blocks are threadedly connected to the threaded rod, the pressure blocks are located between the sealing blocks and on the inner side of the sealing ring 1, the cross-sections of the pressure blocks and the sealing ring 1 are both right-angled trapezoids, and the trapezoidal slopes of the two match.

[0012] Preferably, a lower flange 1 is provided at one end of the second cross-way, the upper flange 1 is connected to the lower flange 1, and the sealing block is installed on the inner wall of the lower flange 1.

[0013] Preferably, a sleeve and a sealing sleeve are fixedly connected on both sides of the fixed disk, a sliding rod is slidably connected to the sleeve, one end of the sliding rod located in the sleeve is fixedly connected to piston 1, the other end of the sliding rod is fixedly connected to a sealing block, and piston 2 is slidably connected to the sealing sleeve. A sealing channel is provided in the fixed disk, and the sealing channel is communicated with the sealing sleeve and the inside of the sleeve respectively; one end of the piston 2 located outside the sealing sleeve is fixedly connected to a sliding block, and an arc-shaped sliding groove is provided at one end of the threaded rod, and the sliding block is slidably connected to the arc-shaped sliding groove. A ball is provided at one end of the sealing channel close to the sleeve, and a limiting block is fixedly connected in the sealing channel, and the limiting block is located above the ball.

[0014] Preferably, the fixed head passes through the fixed disk, and a sealing ring three is arranged inside the fixed head, an elastic sheet is arranged on the fixed head and on the outer wall of the sealing ring three, one end of the elastic sheet is fixedly connected to the fixed head, and the other end is fixedly connected to the threaded rod.

[0015] Preferably, a T-shaped block is fixedly connected to one side of the fixed plate, a T-shaped slot is provided in the tubing hanger, the T-shaped block is located in the T-shaped slot, and the space in the T-shaped slot is larger than that of the T-shaped block, and an elastic block is fixedly connected on the outer wall of the T-shaped block and located in the T-shaped slot.

[0016] Preferably, the second four-way bypass is equipped with a pressure-equalizing valve, and a second pressure monitoring valve is installed on the pressure-equalizing valve.

[0017] Preferably, an upper flange 2 is provided at the other end of the second four-way pipe, a lower flange 2 is provided at one end of the third four-way pipe, the casing hanger is fixedly connected to the inner wall of the lower flange 2, the sealing device 2 includes a sealing ring 4 fixedly connected to the inner wall of the upper flange 2, a heating tube is installed in the sealing ring 4, and the internal material of the sealing ring 4 is low-temperature expanded graphite material.

[0018] Preferably, the third four-way bypass is equipped with an injection valve and a pressure monitoring valve three.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] 1. The present invention provides a test channel and an electric heating channel. During installation, it is only necessary to pass the test pipe and the electric heating pipe into the Christmas tree from the test channel and the electric heating channel respectively. Compared with adding a secondary pipe channel, the difficulty of installation and maintenance is reduced.

[0021] 2. The present invention monitors the pressure difference between the oil pipe and the casing through the pressure sensor arranged on the oil pipe and the casing. When the pressure difference increases, the pressure block moves downward, squeezes the sealing ring outward, increases the friction between the sealing ring and the oil pipe head, and then increases the sealing performance, preventing the sealing ring from loosening due to excessive pressure difference, thereby causing oil leakage.

[0022] 3. The present invention monitors the pressure difference between the oil pipe and the casing by means of pressure sensors arranged on the oil pipe and the casing. When the pressure difference increases, the heating tube in the second sealing device is turned on to heat the graphite material in the second sealing device to expand it, thereby increasing the sealing performance between the casing and the oil pipe head. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is a perspective view of the device of the present invention;

[0024] Figure 2 is a cross-sectional view of the device of the present invention;

[0025] Figure 3 The present invention Figure 2 A partial enlarged view of middle A;

[0026] Figure 4 is a cross-sectional view of the connection between the tubing head and the casing head of the present invention;

[0027] Figure 5 The present invention Figure 4 A partial enlarged view of B in the middle;

[0028] Figure 6 The present invention Figure 5 A partial enlarged view of middle C;

[0029] Figure 7 It is a structural stereogram of the fixed disk of the present invention;

[0030] Figure 8 The present invention Figure 7 A partial enlarged view of D in the middle;

[0031] Fig. 9 It is a structural stereogram of the oil pipe hanger of the present invention.

[0032] In the figure:

[0033] 1. Christmas tree; 11. First four-way; 12. Test channel; 13. Electric heating channel; 14. Main gate; 15. Pressure monitoring valve 1; 16. Production valve; 17. Production pressure monitoring valve; 110. Upper flange 1; 2. Tubing head; 21. Second four-way; 22. Tubing hanger; 221. Tubing; 222. Connecting pipe; 23. Fixed head; 24. Sealing block; 25. Sealing ring 1; 26. Sealing device 1; 261. Threaded rod; 262. Fixed plate; 263. Pressure block; 264. Sleeve; 265. Sealing cylinder; 266. Sliding rod; 267. Piston 1; 268. Plug 2; 269, sealing channel; 2610, slider; 2611, arc-shaped slide groove; 2612, ball; 2613, limit block; 27, lower flange 1; 28, sealing ring 3; 29, elastic sheet; 210, T-block; 211, T-slot; 212, elastic block; 213, flat pressure valve; 214, pressure monitoring valve 2; 215, upper flange 2; 3, casing head; 31, third four-way; 32, casing hanger; 321, casing; 33, sealing device 2; 34, lower flange 2; 35, sealing ring 4; 36, heating tube; 37, injection valve; 38, pressure monitoring valve 3. DETAILED DESCRIPTION

[0034] The following embodiments of the present invention are described in further detail in conjunction with the accompanying drawings and examples. The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0035] Embodiment 1:

[0036] like Figure 1-8As shown, the present invention provides a multifunctional three-tube thermal recovery wellhead device for heavy oil horizontal well electric heating assisted gravity drainage, comprising: a Christmas tree 1, and a tubing head 2 and a casing head 3 installed on the Christmas tree 1 from top to bottom;

[0037] The Christmas tree 1 includes a first four-way pipe 11, and a test channel 12 and an electric heating channel 13 are installed at one end of the first four-way pipe 11. Compared with the inclined auxiliary pipe, the pipeline is directly installed from the vertical direction, and the auxiliary pipe is fixed by a fixing head 23 installed on the oil pipe hanger 22, which reduces the difficulty of installation and prevents damage to the pipeline during installation. The sealing ring 28 and the elastic sheet 29 ensure the sealing of the auxiliary pipe when it passes through the oil pipe hanger 22. The other end of the first four-way pipe 11 is provided with a main gate 14. The test channel 12 and the main gate 14 are respectively located at the two ends of the first four-way pipe 11, and the main gate 14 is used to control the outflow of oil;

[0038] The tubing head 2 comprises a second cross-piece 21, in which a tubing hanger 22 is installed, in which a tubing 221 is suspended, and one end of the tubing 221 is connected to a connecting pipe 222, which is located in the Christmas tree 1. Two fixing heads 23 are arranged on the tubing hanger 22, and the fixing heads 23 fix and seal the pipes passing through the test channel 12 and the electric heating channel 13. The tubing hanger 22 is externally threadedly connected to a plurality of sealing blocks 24, and a sealing ring 25 is arranged between every two sealing blocks 24. By disassembling The seal block 24 is removed to facilitate the replacement of the worn seal ring 25. By moving the seal ring 25, the tightness of the annular fit between the seal ring 25 and the oil pipe 221 is increased to prevent the oil pressure and casing pressure from changing and causing the oil pipe hanger 22 to be impacted, causing the seal ring 25 to be worn and then to have a gap with the lower flange 27, resulting in oil leakage to the oil pipe head 2 outside the oil pipe 221. A seal device 26 is provided in the second cross-piece 21. The seal device 26 moves the seal ring 25 according to the pressure change, so that it always keeps close contact with the oil pipe head 2.

[0039] The casing head 3 includes a third spool 31 in which a casing hanger 32 is installed. A casing 321 is suspended in the casing hanger 32. A second sealing device 33 is provided in the third spool 31 to seal the casing 321 and the tubing head 2 to prevent oil from leaking out of the casing 321.

[0040] The first four-way valve 11 bypasses the pipeline and is respectively installed with a pressure monitoring valve 15 and a production valve 16. The pressure monitoring valve 15 can monitor the oil pressure in the connecting pipe 222 in real time through the pressure sensor installed inside. The production valve 16 can communicate with the connecting pipe 222 through the internal pipeline to discharge the oil and control the flow rate of the produced oil. The production valve 16 is installed with a production pressure monitoring valve 17 to monitor the pressure of the produced oil.

[0041] like Figure 2-6 As shown, an upper flange 110 is provided at the other end of the main gate 14, and a sealing device 26 includes a threaded rod 261 and a fixed disk 262, wherein the fixed disk 262 is fixedly connected to the inner wall of the upper flange 110, the threaded rod 261 is rotatably connected to the fixed disk 262, and passes through the sealing block 24, and a plurality of pressing blocks 263 are threadedly connected to the threaded rod 261, and the pressing blocks 263 are located between the sealing blocks 24 and on the inner side of the sealing ring 25, and the cross-sections of the pressing blocks 263 and the sealing ring 25 are both right-angled trapezoids, and the trapezoidal slopes of the two match.

[0042] A lower flange 27 is provided at one end of the second cross-piece 21, an upper flange 110 is connected to the lower flange 27, a sealing block 24 is threadedly connected to the lower flange 27 via a plurality of connecting columns, and the tubing hanger 22 is mounted on the lower flange 27 via the sealing block 24, thereby facilitating the disassembly of the tubing hanger 22 and the sealing ring 25.

[0043] A sleeve 264 and a sealing sleeve 265 are fixedly connected to both sides of the fixed disk 262, respectively; a slide rod 266 is slidably connected in the sleeve 264; a piston 1 267 is fixedly connected to one end of the slide rod 266 located in the sleeve 264; the other end of the slide rod 266 is fixedly connected to a sealing block 24; a piston 268 is slidably connected in the sealing sleeve 265; a sealing channel 269 is provided in the fixed disk 262; the sealing channel 269 is communicated with the inside of the sealing sleeve 265 and the sleeve 264 respectively; a slider 2610 is fixedly connected to one end of the piston 268 located outside the sealing sleeve 265; an arcuate slide groove 2611 is provided at one end of the threaded rod 261; the slider 2610 is slidably connected to the arcuate slide groove 2611; a ball 2612 is provided at one end of the sealing channel 269 close to the sleeve 264; a limiting block 2613 is fixedly connected in the sealing channel 269; and the limiting block 2613 is located above the ball 2612.

[0044] like Figure 2-6As shown, when the oil pressure and the casing pressure change, the tubing hanger 22 will generate an axial impact, causing the sealing block 24 to vibrate up and down, and causing fatigue damage to the connecting column connecting the sealing block 24 and the lower flange 27, thereby aggravating the friction between the sealing ring 25 and the lower flange 27, thereby causing the sealing ring 25 to wear and generate a gap between the lower flange 27, reducing the sealing performance. Therefore, the sealing ring 25 is movably arranged between the sealing blocks 24, so that the position of the sealing ring 25 can be adjusted by the sealing device 26 to keep it in close contact with the inner wall of the lower flange 27. The sealing block 24 is connected by a sliding rod 266. When the sealing block 24 moves, it drives the sliding rod 266 to move, thereby causing the piston 267 to move up and down. When the piston 267 moves downward, the volume of the space above the sleeve 264 increases, the pressure decreases, and the space below the sleeve 264 is compressed. It is connected to the external space through the upper flange 110 to provide air for the sleeve 264. When the piston 1 267 moves upward, the volume above the sleeve 264 becomes smaller, and the air is pressed into the sealing tube 265, and the piston 268 is pushed upward, thereby driving the slider 2610 on the piston 268 to move upward. Because the slider 2610 is slidably connected in the arc-shaped slide groove 2611 of the threaded rod 261, and the vertical position of the slider 2610 remains unchanged, the slider 2610 slides in the arc-shaped slide groove 2611 when it rises, and pushes the threaded rod 261 to rotate; because the threaded rod 261 is threadedly connected to the pressure block 263, and the pressure block 263 is located between the sealing blocks 24, the rotation of the threaded rod 261 drives the pressure block 263 to move downward, so that the pressure block 263 squeezes the sealing ring 25 toward the inner wall of the lower flange 27.

[0045] It should be noted that, because piston 1 267 vibrates up and down by connecting to sealing block 24, piston 268 is driven to rise a certain distance, so that threaded rod 261 rotates a few tenths of a turn, and sealing ring 25 is squeezed toward the inner wall of upper flange 110 through pressure block 263, thereby compensating for the wear of sealing ring 25, so that sealing ring 25 and lower flange 27 always maintain close contact, thereby enhancing the sealing performance of sealing ring 25; when slider 2610 on piston 268 moves to the top of arc-shaped slide groove 2611, it squeezes the pressure alarm above threaded rod 261, and the pressure alarm sends an alarm message to the staff, indicating that the number of rotations of threaded rod 261 has reached the limit, and the staff disassembles and replaces threaded rod 261, thereby increasing the service life of sealing device 26.

[0046] It should be noted that if Figure 6As shown, when the air in the sleeve 264 enters the sealing cylinder 265, the ball 2612 is pushed upward to make it contact with the limit block 2613, so that the air enters from the gap between the ball 2612 and the limit block 2613; when the air in the sleeve 264 does not push the ball 2612, the air in the sealing cylinder 265 pushes the ball 2612 downward to make it fit with the bottom of the sealing channel 269, thereby closing the sealing channel 269 and preventing the air in the sealing cylinder 265 from leaking, while preventing the threaded rod 261 from being blocked and pressing the air in the sealing cylinder 265 into the sleeve 264.

[0047] It should be noted that piston 267 is made of elastic material. When piston 267 moves upward to compress the air, piston 267 expands outward and fits against the inner wall of sleeve 264 to prevent air leakage above sleeve 264. When sealing ring 25 is less worn, threaded rod 261 is subject to greater resistance and cannot rotate to push pressure block 263 to move, and piston 268 cannot continue to rise. Therefore, piston 267 cannot squeeze the air in sleeve 264 into sealing cylinder 265 when it rises. Because piston 267 is made of elastic material, the compressed gas in sleeve 264 squeezes piston 267 in the opposite direction, causing piston 267 to deform, thereby causing the air above sleeve 264 to flow from the gap between piston 267 and sleeve 264 to the space below sleeve 264, thereby preventing sealing ring 25 from being over-extruded, thereby causing further wear of sealing ring 25 and reducing the sealing performance.

[0048] The second four-way bypass 21 is provided with a pressure-equalizing valve 213 , which balances the oil pressure and the casing pressure by injecting air or water into the tubing head 2 . A second pressure monitoring valve 214 is installed on the pressure-equalizing valve 213 .

[0049] like Figure 4 As shown, the other end of the second four-way pipe 21 is provided with an upper flange 215, and the one end of the third four-way pipe 31 is provided with a lower flange 234. The casing hanger 32 is fixedly connected to the inner wall of the lower flange 234. The sealing device 233 includes a sealing ring 435 fixedly connected to the inner wall of the upper flange 215. A heating pipe 36 is installed in the sealing ring 435. The internal material of the sealing ring 435 is low-temperature expanded graphite material. The pressure difference between the oil pipe 221 and the casing 321 is monitored by the pressure sensor provided on the oil pipe 221 and the casing 321. When the pressure difference increases, the sealing ring 435 may be deformed. The heating pipe 36 in the sealing device 233 is turned on to heat the low-temperature expanded graphite material in the sealing device 233 to expand it, thereby increasing the contact area between the sealing ring 435 and the casing 321, thereby increasing the sealing performance of the casing 321 and the tubing head 2; at the same time, the oil temperature can be increased by heating to prevent the paraffin in the petroleum from cooling and solidifying in the oil pipe 221.

[0050] It should be noted that low-temperature expanded graphite is a graphite product that uses perchloric acid as an intercalating agent and potassium permanganate as an oxidant, and controls the reaction temperature, time, and drying temperature to react with graphite to increase the distance between graphite layers, thereby reducing its initial expansion temperature. It will not affect petroleum.

[0051] The third four-way bypass 31 is installed with an injection valve 37 and a pressure monitoring valve 38. Cement is injected into the annular ring of the casing 321 through the injection valve 37 to fix the casing 321, and the pressure of the annular ring of the casing 321 is monitored through the pressure monitoring valve 38.

[0052] Embodiment 2:

[0053] like Fig. 9 As shown, a T-shaped block 210 is fixedly connected to one side of the fixed plate 262, a T-shaped slot 211 is provided in the tubing hanger 22, the T-shaped block 210 is located in the T-shaped slot 211, and the space in the T-shaped slot 211 is larger than that of the T-shaped block 210, and an elastic block 212 is fixedly connected on the outer wall of the T-shaped block 210 and located in the T-shaped slot 211. When the pressure difference causes the tubing hanger 22 to move, the T-shaped block 210 on the fixed plate 262 is arranged in the T-shaped slot 211, so that the elastic block 212 on the T-shaped block 210 buffers the tubing hanger 22, thereby reducing the axial pressure on the tubing hanger 22 and the torsional force caused by the unstable pressure difference, reducing the damage to the sealing ring 25 in the tubing hanger 22, and further improving the sealing performance.

[0054] Embodiment three:

[0055] like Figure 7-8 As shown, the fixed head 23 passes through the fixed disk 262, and a sealing ring 3 28 is arranged inside the fixed head 23, and an elastic sheet 29 is arranged on the fixed head 23 and on the outer wall of the sealing ring 3 28, one end of the elastic sheet 29 is fixedly connected to the fixed head 23, and the other end is fixedly connected to the threaded rod 261; when the threaded rod 261 rotates, one end of the elastic sheet 29 is pulled, so that the elastic sheet 29 tightens the sealing ring 3 28, so that the sealing ring 3 28 is tightly fitted with the pipeline, thereby improving the sealing performance of the pipeline and the oil pipe hanger 22.

[0056] The embodiments of the present invention are provided for the purpose of illustration and description. Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations of the present invention. Ordinary technicians in this field can change, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. A multifunctional three-tube thermal recovery wellhead device for heavy oil horizontal well electric heating assisted gravity drainage, comprising: A Christmas tree (1), and a tubing head (2) and a casing head (3) installed from top to bottom on the Christmas tree (1), characterized in that: The Christmas tree (1) comprises a first cross-piece (11), one end of which is provided with a test channel (12) and an electric heating channel (13), and the other end of which is provided with a main gate (14), the test channel (12) and the main gate (14) being located at two ends of the first cross-piece (11), respectively, and the main gate (14) being used to control the outflow of oil; The tubing head (2) comprises a second cross-piece (21), a tubing hanger (22) is installed in the second cross-piece (21), a tubing (221) is suspended in the tubing hanger (22), one end of the tubing (221) is connected to a connecting pipe (222), the connecting pipe (222) is located in the Christmas tree (1), two fixing heads (23) are arranged on the tubing hanger (22), the fixing heads (23) fix and seal the pipeline passing through the test channel (12) and the electric heating channel (13), the tubing hanger (22) is externally threaded with a plurality of sealing blocks (24), a sealing ring (25) is arranged between every two sealing blocks (24), a sealing device (26) is arranged in the second cross-piece (21), the sealing device (26) moves the sealing ring (25) according to pressure changes, so that the sealing device (26) always maintains close contact with the tubing head (2); An upper flange (110) is provided at one end of the main gate (14); the sealing device (26) comprises a threaded rod (261) and a fixed disk (262); the fixed disk (262) is fixedly connected to the inner wall of the upper flange (110); the threaded rod (261) is rotatably connected to the fixed disk (262) and penetrates the sealing block (24); a plurality of pressing blocks (263) are threadedly connected to the threaded rod (261); the pressing blocks (263) are located between the sealing blocks (24) and on the inner side of the sealing ring (25); the cross-sections of the pressing blocks (263) and the sealing ring (25) are both right-angled trapezoids, and the trapezoidal slopes of the two are matched; The casing head (3) comprises a third cross-piece (31), a casing hanger (32) is installed in the third cross-piece (31), a casing (321) is suspended in the casing hanger (32), and a second sealing device (33) is arranged in the third cross-piece (31), the second sealing device (33) seals the casing (321) and the tubing head (2); An upper flange 2 (215) is provided at one end of the second four-way connection (21), a lower flange 2 (34) is provided at one end of the third four-way connection (31), the casing hanger (32) is fixedly connected to the inner wall of the lower flange 2 (34), the sealing device 2 (33) comprises a sealing ring 4 (35) fixedly connected to the inner wall of the upper flange 2 (215), a heating tube (36) is installed in the sealing ring 4 (35), and the internal material of the sealing ring 4 (35) is a low-temperature expanded graphite material.

2. The multifunctional three-tube thermal recovery wellhead device for heavy oil horizontal well electrically heated and gravity-assisted oil drainage according to claim 1, characterized in that: The first four-way (11) bypass pipeline is respectively installed with a pressure monitoring valve (15) and a production valve (16), and the production valve (16) is installed with a production pressure monitoring valve (17).

3. The multifunctional three-tube thermal recovery wellhead device for heavy oil horizontal well electric heating assisted gravity drainage according to claim 1, characterized in that: The other end of the second cross-connection (21) is provided with a lower flange one (27), the upper flange one (110) is connected to the lower flange one (27), and the sealing block (24) is mounted on the inner wall of the lower flange one (27).

4. The multifunctional three-tube thermal recovery wellhead device for heavy oil horizontal well electric heating assisted gravity drainage as claimed in claim 3, characterized in that: The fixed disk (262) is fixedly connected to a sleeve (264) and a sealing cylinder (265) on both sides thereof, the sleeve (264) is slidably connected to a slide rod (266), one end of the slide rod (266) located in the sleeve (264) is fixedly connected to a piston 1 (267), the other end of the slide rod (266) is fixedly connected to a sealing block (24), the sealing cylinder (265) is slidably connected to a piston 2 (268), the fixed disk (262) is provided with a sealing channel (269), the sealing channel (269) is respectively connected to the sealing cylinder (2 65) and the interior of the sleeve (264) are communicated with each other, one end of the piston 2 (268) located outside the sealing cylinder (265) is fixedly connected with a slider (2610), one end of the threaded rod (261) is provided with an arc-shaped slide groove (2611), the slider (2610) is slidably connected to the arc-shaped slide groove (2611), and the sealing channel (269) is provided with a ball (2612) at one end close to the sleeve (264), and a limit block (2613) is fixedly connected in the sealing channel (269), and the limit block (2613) is located above the ball (2612).

5. The multifunctional three-tube thermal recovery wellhead device for heavy oil horizontal well electric heating assisted gravity drainage as claimed in claim 4, characterized in that: The fixed head (23) passes through the fixed disk (262), and a sealing ring three (28) is arranged inside the fixed head (23). An elastic sheet (29) is arranged on the fixed head (23) and on the outer wall of the sealing ring three (28). One end of the elastic sheet (29) is fixedly connected to the fixed head (23), and the other end is fixedly connected to the threaded rod (261).

6. The multifunctional three-tube thermal recovery wellhead device for heavy oil horizontal well electric heating assisted gravity drainage according to claim 1, characterized in that: A T-shaped block (210) is fixedly connected to one side of the fixed plate (262); a T-shaped slot (211) is provided in the tubing hanger (22); the T-shaped block (210) is located in the T-shaped slot (211); the space in the T-shaped slot (211) is larger than that in the T-shaped block (210); and an elastic block (212) is fixedly connected to the outer wall of the T-shaped block (210) and located in the T-shaped slot (211).

7. The multifunctional three-tube thermal recovery wellhead device for heavy oil horizontal well electric heating assisted gravity drainage according to claim 1, characterized in that: A pressure-equalizing valve (213) is installed in the bypass of the second four-way valve (21), and a second pressure monitoring valve (214) is installed on the pressure-equalizing valve (213).

8. The multifunctional three-tube thermal recovery wellhead device for heavy oil horizontal well electrically heated and gravity-assisted oil drainage according to claim 1, characterized in that: The third four-way valve (31) is bypassed with an injection valve (37) and a third pressure monitoring valve (38).

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