Wellhead device of coiled tubing velocity string and using method thereof

Abstract

The invention relates to the technical field of oil and gas field development, in particular to a coiled tubing velocity string wellhead device and a using method thereof, and aims to solve the technical problem of low suspension and installation efficiency of a velocity string in related technologies. According to the coiled tubing velocity string wellhead device, the descending velocity string can be fastened through the suspension mechanism, and the annulus between the velocity string and the outer barrel can be sealed through the sealing mechanism; the driving assembly is controlled to drive the rotating tool rest to rotate, the shifting fork piece synchronously rotates forwards or backwards along with the rotating tool rest, and when passing through the shifting piece gear, the shifting fork piece correspondingly rotates around the axis of the rotating shaft, so that the cutting knife is driven through the transmission assembly, and the cutting knife moves forwards to cut a speed tubular column or retreats to be separated from the end face of the speed tubular column. By the adoption of the coiled tubing velocity string wellhead device, operation under pressure can be carried out, well killing is not needed, stratum pollution is avoided, and meanwhile tedious operation such as induced flow activation after well completion of a conventional velocity string is overcome.

Description

Technical Field

[0001] The present invention relates to the technical field of oil and gas field development, and particularly relates to a coiled tubing velocity string wellhead device and a using method thereof. Background Art

[0002] In gas wells, water-bearing gas wells or production wells in bottom water gas reservoirs, during the middle and late production stages, along with the attenuation of formation pressure, the decrease in gas volume and the increase in water production, the gas flow velocity in the production string decreases, resulting in slippage loss in the string, poor liquid-carrying capacity, causing liquid accumulation at the bottom of the well and forming a water column of a certain height in the bottom section of the well, leading to a decrease in production pressure difference, resulting in a decrease in gas production or even a blowout and production suspension, that is, the original string has poor liquid-carrying capacity or can no longer meet the liquid-carrying requirements. Using a velocity string is an effective means to solve this problem. Its principle is to reduce the pipe diameter, so that the fluid velocity on the flow cross-section increases, increasing the gas (well fluid) flow velocity, improving and enhancing the liquid-carrying capacity. This method of velocity string is the most effective means to quickly resume gas well production, and there is no other effective means to replace it.

[0003] Currently, there are many patents related to coiled tubing velocity strings, but their hanging and installation methods are basically connecting a plug at the bottom, lowering it to the appropriate position of the operation window, cutting the coiled tubing, hanging the velocity string well, and then knocking out the plug, etc. It includes the following steps: 1. Install wellhead equipment, including a wellhead production tree cross, a blowout preventer, an operation window, a blowout prevention pipe, and an injection head connected in sequence from bottom to top; 2. After lowering the coiled tubing string with an internal plugging tool installed at the end to the target depth at the bottom of the well, hang the coiled tubing through the wellhead blowout preventer and seal the annulus formed by the coiled tubing and the production tubing; 3. Open the operation window and cut the coiled tubing at an appropriate position, and install a hanging packer between the upper section of the coiled tubing and the lower section of the coiled tubing after cutting; 4. Release the wellhead hanging of the coiled tubing by the blowout preventer and the sealing of the annulus; 5. Lower the hanging packer to a predetermined distance below the wellhead through the injection head, set and test the hanging packer; 6. Close the operation window; 7. Remove the wellhead cross and all equipment above it; 8. Knock out the bottom plugging tool. Existing defects: 1. In most cases, well killing is required; 2. It is necessary to use a plugging tool to plug the inner cavity of the velocity string and it needs to be knocked out after construction; 3. Cutting, etc. needs to be operated within the operation window; 4. String adjustment is difficult; 5. The efficiency is low. Summary of the Invention

[0004] The purpose of the present invention is to provide a coiled tubing velocity string wellhead device and a using method thereof to alleviate the technical problem of low hanging and installation efficiency of the velocity string in related technologies.

[0005] To solve the above technical problems, the technical solution provided by the present invention lies in:

[0006] In a first aspect, the present invention provides a coiled tubing velocity string wellhead device, comprising: a sealing and hanging assembly, a cutting and releasing assembly, an oil outlet four-way joint, and a flap gate valve;

[0007] The sealing and hanging assembly includes an outer cylinder body, a sealing mechanism, and a hanging mechanism;

[0008] Both ends of the outer cylinder body are provided with connecting flanges for connecting to the wellhead gas production tree and the cutting and releasing assembly respectively. A partition joint is provided in the middle of the outer cylinder body. The partition joint serves as an isolation structure between the sealing mechanism and the hanging mechanism and cooperates with a limit retaining ring threadedly connected to the inner wall of the outer cylinder body to fix the sealing mechanism and the hanging mechanism;

[0009] The sealing mechanism is arranged inside the outer cylinder body and is used to seal the annulus formed between the outer cylinder body and the velocity string;

[0010] The hanging mechanism is arranged inside the outer cylinder body and is used to fasten the velocity string to the outer cylinder body;

[0011] The cutting and releasing assembly includes a flange cylinder body housing, a power mechanism, and a cutting mechanism;

[0012] The flange cylinder body housing is in a cylindrical shape, and fixed flanges are respectively provided at both ends thereof for connecting to the oil outlet four-way joint and the connecting flange of the outer cylinder body. A retaining piece stop is provided on the inner wall of the flange cylinder body housing;

[0013] The power mechanism is located inside the flange cylinder body housing and includes a rotating tool holder and a driving assembly. Among them, the rotating tool holder is provided with a receiving channel passing through itself and extending along the axial direction of the flange cylinder body housing for passing through the velocity string. The driving assembly is fixed to the flange cylinder body housing and is in transmission connection with the rotating tool holder to drive the rotating tool holder to rotate forward or backward around the axis of the receiving channel;

[0014] The cutting mechanism is located inside the flange cylinder body housing and is arranged on the side wall of the rotating tool holder, and includes a fork piece, a cutting tool, and a transmission assembly;

[0015] The fork piece is rotatably matched with the rotating tool holder through a rotating shaft and is also in transmission connection with the cutting tool through the transmission assembly. The fork piece can pass through the retaining piece stop under the working conditions of the forward or backward rotation of the rotating tool holder and rotate correspondingly around the axis of the rotating shaft under the blocking of the retaining piece stop;

[0016] The transmission assembly is configured to drive the cutting tool to move in a direction perpendicular to the axis of the flange cylinder body housing under the working condition that the fork piece rotates correspondingly around the axis of the rotating shaft, so as to move forward into the receiving channel or retreat out of the receiving channel;

[0017] The flap gate valve is connected to the oil outlet four-way flange so as to be in an open state when the velocity string is put into operation and in a closed state when the velocity string is pulled out.

[0018] Further, the transmission assembly includes a differential thread feed shaft and an advance / retract sliding tool holder;

[0019] A supporting tool holder is fixed to the side wall of the rotating tool holder;

[0020] The differential thread feed shaft constitutes the rotating shaft, and one end of the differential thread feed shaft is provided with two sections of lead screws with different pitches, namely left-handed and right-handed, the left-handed thread cooperates with the thread on the supporting tool holder, and the right-handed thread cooperates with the thread on the advancing / retreating sliding tool holder, and the other end is used to install the shift fork plate;

[0021] The advance / retreat sliding tool holder is slidably matched with the supporting tool holder, and the sliding path extends along the axial direction of the differential thread feed shaft and is perpendicular to the axis of the accommodating channel;

[0022] The cutting knife is fixed to the advance / retreat sliding knife holder.

[0023] Furthermore, a concave hole is provided at a portion of the support tool holder close to the left-handed thread of the differential thread feed shaft for cooperating with a spring top ball to form an anti-retraction top ball structure.

[0024] Furthermore, the shift fork piece includes a fixed ring and a plurality of shifting leaves;

[0025] The fixing ring is installed at one end of the differential thread feed shaft away from the cutting knife, and the inner wall of the fixing ring is matched with the side surface of the differential thread feed shaft through an anti-overload top bead structure;

[0026] One end of the moving blade is fixedly connected to the outer wall of the fixing ring, and the other end extends in the radial direction of the fixing ring toward a direction away from the fixing ring;

[0027] A plurality of the shifting blades are distributed at intervals along the circumference of the fixing ring.

[0028] Furthermore, a limit ring is provided on the inner wall of the rotating tool holder;

[0029] The limit stop ring is located on the sliding path of the advance / retreat sliding tool holder and can abut against the advance / retreat sliding tool holder after the cutting knife has cut the speed column.

[0030] Further, the drive assembly includes a motor hollow shaft / coupling and a hydraulic motor;

[0031] The hydraulic motor injects / circulates hydraulic oil through the hydraulic motor injection / circulation interface to provide power to make the motor hollow shaft / coupling rotate forward or reverse;

[0032] The hollow shaft / coupling of the motor is bolted to the rotary tool rest.

[0033] Furthermore, the sealing mechanism includes a first sealing retaining ring, a sealing piston sleeve, a semi-circular sealing assembly support body, and a semi-circular sealing rubber tube assembly;

[0034] There are two first sealing retaining rings, which are spaced apart and sleeved on the sealing piston sleeve, and are threadedly connected to the outer cylinder to enclose a first liquid chamber with the outer wall of the sealing piston sleeve and the inner wall of the outer cylinder;

[0035] Along the circumferential direction of the sealing piston sleeve, a first convex platform protrudes from the outer wall of the sealing piston sleeve, and the first convex platform abuts against the inner wall of the outer cylinder to divide the first liquid chamber into two non-communicating first sub-liquid chambers;

[0036] Two sealing mechanism injection / circulation interfaces are provided on the side wall of the outer cylinder, and the two sealing mechanism injection / circulation interfaces are respectively communicated with the two first sub-liquid chambers;

[0037] The semi-circular sealing assembly support body is a semi-circular ring-shaped body, and the two symmetric semi-circular sealing assembly support bodies enclose to form an outer seal for the velocity pipe string. A groove is transversely opened at the lower position of each semi-circular sealing assembly support body to install the semi-circular sealing rubber tube assembly;

[0038] The outer side of the upper position of each semi-circular sealing assembly support body is an inclined cone, and a dovetail tapered panel key is provided on the inclined cone;

[0039] The sealing piston sleeve is sleeved on the semi-circular sealing assembly support body, and its top end is provided with an inclined cone that matches the inclined cone of the semi-circular sealing assembly support body. A dovetail tapered panel groove is provided on the inclined cone of the sealing piston sleeve to cooperate with the two dovetail tapered panel keys of the semi-circular sealing assembly support body respectively;

[0040] The two conical surfaces of the semi-circular sealing assembly support body and the sealing piston sleeve are designed with a self-locking angle.

[0041] Furthermore, the suspension mechanism includes a second sealing retaining ring, a slip piston sleeve, and a slip body;

[0042] There are two second sealing retaining rings, which are spaced apart and sleeved on the slip piston sleeve, and are threadedly connected to the outer cylinder to enclose a second liquid chamber with the outer wall of the slip piston sleeve and the inner wall of the outer cylinder;

[0043] A second boss is formed on the outer wall of the slip piston sleeve along the circumference of the slip piston sleeve, and the second boss abuts against the inner wall of the outer cylinder to separate the second liquid storage chamber into two second sub-liquid storage chambers that are not connected to each other;

[0044] Two suspension mechanism injection / circulation interfaces are arranged on the side wall of the outer cylinder, and the two suspension mechanism injection / circulation interfaces are respectively connected to the two second sub-liquid chambers;

[0045] The slip body is a two-petal body, and the two symmetrical slip bodies enclose the speed column suspension. The inner surface of each slip body is provided with a bidirectional slip tooth to limit the movement of the speed column. The outer side of the slip body is an inclined cone, and the inclined cone is provided with a dovetail cone panel key;

[0046] The slip piston sleeve is sleeved on the slip body, and a sloped cone matching the sloped cone of the slip body is provided at the bottom end thereof, and dovetail cone panel grooves are respectively provided on the sloped cone of the slip piston sleeve to match the dovetail cone panel keys of the slip body respectively;

[0047] The two conical surfaces of the slip piston sleeve and the slip body are designed with self-locking angles.

[0048] Furthermore, the flap gate valve comprises a gate valve housing, a tongue-shaped gate plate and a return spring;

[0049] The gate valve housing is fixedly connected to one end of the oil outlet 4-way away from the flange cylinder housing, and is provided with a flow passage penetrating through the gate valve housing and communicating with the oil outlet 4-way;

[0050] The tongue-shaped gate is arranged in the gate valve housing in a posture of blocking the flow passage, and one side of the tongue-shaped gate is hinged to the gate valve housing through a gate core shaft;

[0051] The axis of the gate core shaft is perpendicular to the axis of the flow passage;

[0052] The reset spring is sleeved on the gate core shaft and is respectively connected to the gate valve housing and the tongue-shaped gate. The reset spring enables the tongue-shaped gate to rotate around the axis of the gate core shaft in the direction of blocking the flow channel.

[0053] In a second aspect, the present invention further provides a method for using a coiled tubing velocity string wellhead device, the method is based on the coiled tubing velocity string wellhead device described above, and comprises the following steps:

[0054] S1: Establish and install velocity string;

[0055] S101: Connect the coiled tubing velocity string wellhead device to the original wellhead gas (oil) tree;

[0056] S102: Lower the velocity string to a predetermined depth;

[0057] S103: Select the injection / circulation interface of the suspension mechanism to inject liquid into the corresponding second sub-chamber, so that the two sub-slip bodies are tightened, and lock after confirming the suspension;

[0058] S104: Select the injection / circulation interface of the sealing mechanism to inject liquid into the corresponding first sub-chamber, so that the two sub-semicircular sealing assembly carriers are tightened, and then pressure test according to the standard;

[0059] S105: Select the injection / circulation interface of the corresponding hydraulic motor to inject liquid into the hydraulic motor. After the load of the injected hydraulic oil decreases, lift the velocity string to confirm that the velocity string is cut off;

[0060] S106: Pull out the remaining velocity string;

[0061] S107: Install the surface production process according to the production function, and start production after the pressure test is qualified;

[0062] S2: Replace or remove the velocity string;

[0063] S201: Insert the coiled tubing fishing joint with a positive one-way flow function into the coiled tubing velocity string wellhead device, and dock with the velocity string remaining in the wellbore;

[0064] S202: After the injection head lifts the load to confirm the fishing, pressure test in sequence to open the sealing mechanism and the suspension mechanism;

[0065] S203: Lift the fished velocity string and the coiled tubing fishing joint to the ground.

[0066] Based on the above technical solutions, the beneficial effects of the present invention are:

[0067] Without moving the wellbore string and without killing the well, lower the coiled tubing to the completion position, retain the coiled tubing and the tools carried thereon in the well and install them to form a velocity string, improve the gas-oil-water flow pattern in the wellbore, so as to achieve the purpose of increasing the gas-liquid flow velocity, reducing the bottom-hole liquid accumulation and reducing the slip loss, and restoring the production of the gas well. The beneficial effects are:

[0068] 1. The wellhead is integrated and compact, with characteristics such as flange connection, large diameter, and no operation window, and can withstand a relatively high pressure.

[0069] 2. A large-tonnage suspension capacity, a large-size coiled tubing can be used as the velocity string, and tool fishing, flow control and other operations can be carried out inside the velocity string.

[0070] 3. The work under pressure has an essential difference in superiority from the conventional velocity string. Since there is no need to kill the well, it avoids formation contamination and overcomes the cumbersome operations such as induced blowout activation after the completion of the conventional velocity string.

[0071] 4. The adjustment and removal of the velocity string are convenient and fast and do not require well killing, which is different from the adjustment and removal of the conventional velocity string that requires well killing, lifting the wellhead, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0072] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0073] Figure 1 It is a schematic structural diagram of the coiled tubing velocity string wellhead device provided by the embodiment of the present invention;

[0074] Figure 2 It is a cross-sectional view of the cutting and releasing assembly provided by the embodiment of the present invention;

[0075] Figure 3 It is a transmission schematic diagram of the cutting tool provided by the embodiment of the present invention;

[0076] Figure 4 It is a connection schematic diagram of the fork piece and the differential thread feed shaft provided by the embodiment of the present invention;

[0077] Figure 5 It is Figure 4 a partial cross-sectional view of;

[0078] Figure 6 It is a cross-sectional view of the seal suspension assembly provided by the embodiment of the present invention;

[0079] Figure 7 It is a schematic structural diagram of the semi-circular seal assembly support body provided by the embodiment of the present invention;

[0080] Figure 8 It is a cross-sectional view of the semi-circular seal assembly support body provided by the embodiment of the present invention;

[0081] Figure 9 It is a cross-sectional view of the slip piston sleeve provided by the embodiment of the present invention;

[0082] Figure 10 It is a schematic structural diagram of the slip body provided by the embodiment of the present invention;

[0083] Figure 11 It is a top view of the slip body provided by the embodiment of the present invention;

[0084] Figure 12 It is a cross-sectional view of the slip body provided by the embodiment of the present invention;

[0085] Figure 13 It is a cross-sectional view of the flap gate valve provided by the embodiment of the present invention.

[0086] Icon: 1 - Sealing suspension assembly; 101 - Outer cylinder; 102 - First sealing retaining ring; 103 - Sealing piston sleeve; 104 - Semi-circular sealing assembly carrier; 105 - Annular sealing rubber barrel assembly; 106 - First boss; 107 - Sealing mechanism injection / circulation interface; 108 - Second sealing retaining ring; 109 - Slip piston sleeve; 110 - Slip body; 111 - Second boss; 112 - Suspension mechanism injection / circulation interface; 113 - Limit retaining ring; 114 - Connecting flange; 115 - Partition joint; 116 - Sealing ring;

[0087] 2 - Cutting and releasing assembly; 201 - Flange cylinder housing; 202 - Paddle stop; 203 - Rotary tool holder; 204 - Fork piece; 205 - Cutting tool; 206 - Differential thread feed shaft; 207 - In / retreat sliding tool holder; 208 - Support tool holder; 209 - Anti-retreat top bead structure; 210 - Anti-overload top bead structure; 211 - Limit retaining ring; 212 - Hydraulic motor injection / circulation interface; 213 - Motor hollow shaft / coupling; 214 - Hydraulic motor; 215 - Fixing bolt; 216 - Fixing flange;

[0088] 3 - Velocity string; 4 - Oil outlet four-way;

[0089] 5 - Flap gate valve; 501 - Gate valve housing; 502 - Tongue-shaped gate plate; 503 - Return spring; 504 - Gate plate core shaft; 505 - Flap sealing ring. Detailed implementation manners

[0090] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, 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 embodiments are some but not all of the embodiments of the present invention. Usually, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0091] Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed present invention, but merely represents the selected embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0092] The following will describe in detail some embodiments of the present invention with reference to the accompanying drawings. Without conflict, the following embodiments and the features in the embodiments can be combined with each other.

[0093] In most cases, when the velocity string is suspended and installed, well killing is required, and it must be cut within the operation window, which increases the operation difficulty and results in low efficiency.

[0094] In view of this, the present invention provides a coiled tubing velocity string wellhead device, which includes a sealing and hanging assembly 1 and a cutting and releasing assembly 2; the sealing and hanging assembly 1 includes an outer cylinder 101, a sealing mechanism and a hanging mechanism; both ends of the outer cylinder 101 are provided with connecting flanges 114 for connecting the wellhead gas production tree and the cutting and releasing assembly 2 respectively, and a partition joint 115 is arranged in the middle of the outer cylinder 101. The partition joint 115 serves as an isolation structure between the sealing mechanism and the hanging mechanism, and cooperates with a limit retaining ring 113 screwed on the inner wall of the outer cylinder 101 to fix the sealing mechanism and the hanging mechanism; the sealing mechanism is arranged in the outer cylinder 101 and is used to seal the annulus formed between the outer cylinder 101 and the velocity string 3; the hanging mechanism is arranged in the outer cylinder 101 and is used to fasten the velocity string 3 to the outer cylinder 101; the cutting and releasing assembly 2 includes a flange cylinder housing 201, a power mechanism and a cutting mechanism; the flange cylinder housing 201 is in a cylindrical shape, and fixed flanges 216 are respectively arranged at both ends thereof for connecting with the oil outlet four-way 4 and the connecting flange 114 of the outer cylinder 101, and a flap stop 202 is arranged on the inner wall of the flange cylinder housing 201; the power mechanism is in the flange cylinder housing 201 and includes a rotary tool rest 203 and a driving assembly. Among them, the rotary tool rest 203 is provided with a receiving channel penetrating through itself and extending along the axis of the flange cylinder housing 201 for passing through the velocity string 3, and the driving assembly is fixed to the flange cylinder housing 201 and is in transmission connection with the rotary tool rest 203 to drive the rotary tool rest 203 to rotate forward or backward around the axis of the receiving channel; the cutting mechanism is in the flange cylinder housing 201 and is arranged on the side wall of the rotary tool rest 203, and includes a fork piece 204, a cutting tool 205 and a transmission assembly; the fork piece 204 is rotationally matched with the rotary tool rest 203 through a rotating shaft, and is also in transmission connection with the cutting tool 205 through the transmission assembly. The fork piece 204 can pass through the flap stop 202 under the working conditions of the forward or reverse rotation of the rotary tool rest 203, and rotate correspondingly around the axis of the rotating shaft under the blocking of the flap stop 202; the transmission assembly is configured to drive the cutting tool 205 to move in a direction perpendicular to the axis of the flange cylinder housing 201 when the fork piece 204 rotates correspondingly around the axis of the rotating shaft, so as to advance into the receiving channel or retreat out of the receiving channel; the flap gate valve 5 is flange-connected to the oil outlet four-way 4 and is configured to be in an open state when the velocity string 3 is inserted and in a closed state when the velocity string 3 is withdrawn.

[0095] In the coiled tubing velocity string wellhead device, the suspension mechanism can fasten the velocity string 3 that has been lowered, thereby hanging the velocity string 3; the sealing mechanism can seal the annulus between the velocity string 3 and the outer cylinder 101, thereby blocking the annulus; after the velocity string 3 is hung and sealed, the rotation direction of the rotating tool holder 203 is driven by controlling the driving assembly, and the fork piece 204 rotates forward or reversely synchronously with the rotating tool holder 203, and when passing through the fork piece block 202, the fork piece 204 also rotates correspondingly around the axis of the rotating shaft, thereby driving the cutting knife 205 through the transmission assembly, so that the cutting knife 205 moves forward or backward; when the cutting knife 205 moves forward, the velocity string 3 is cut, and when the cutting knife 205 moves backward, it is separated from the end face of the velocity string 3.

[0096] It can be seen that without moving the tubing in the well or killing the well, the coiled tubing is lowered to the completion site, and the coiled tubing and the tools carried are retained and installed in the well to improve the gas, oil and water flow state in the wellbore, thereby increasing the gas and liquid flow rate, reducing the bottom hole liquid accumulation, reducing the slip loss, and resuming production of the gas well. Its beneficial effects are:

[0097] 1. The wellhead is compactly integrated, with flange connection, large diameter, no operation window and other features, and can withstand higher pressure.

[0098] 2. For large tonnage suspension, large-size continuous tubing can be used as the velocity string, and operations such as tool casting and flow control can be carried out in the velocity string.

[0099] 3. The advantages of pressure-operated operation are essentially different from those of conventional velocity strings. Since there is no need to kill the well, formation pollution is avoided and tedious operations such as activation of induced blowout after completion of conventional velocity strings are overcome.

[0100] 4. The adjustment and removal of the velocity string is convenient and quick without well killing, which is different from the adjustment and removal of the conventional velocity string, which requires well killing and pulling up the wellhead.

[0101] The following combination Figures 1 to 13 The structure and shape of the coiled tubing velocity string wellhead device provided in this embodiment are described in detail:

[0102] Regarding the cutting release assembly 2, specifically:

[0103] refer to Figures 1 to 5The upper and lower ends of the flange cylinder shell 201 are respectively connected to the oil outlet 4 and the outer cylinder 101 by the fixed flange 216; the driving assembly, i.e., the power part, is mainly composed of a hydraulic motor 214 and a motor hollow shaft / coupling 213. The hydraulic motor 214 is installed on the flange cylinder shell 201 by fixing bolts 215. The power is provided by injecting hydraulic oil into the hydraulic motor injection / circulation interface 212 of the hydraulic motor 214, so that the motor hollow shaft / coupling 213 of the hydraulic motor 214 rotates. The direction of rotation of the fork piece 204 around the axis of the rotating shaft is adjusted by forward and reverse rotation, so that the cutting knife 205 moves forward for cutting or moves backward for retracting. Here, the inner space of the motor hollow shaft / coupling 213 is mainly to allow the speed column 3 to pass through.

[0104] In accordance with the above, the transmission assembly includes a differential thread feed shaft 206 and an advance / retract sliding tool holder 207, and a support tool holder 208 is fixed to the side wall of the rotating tool holder 203; the differential thread feed shaft 206 constitutes a rotating shaft, and along the axial direction of the differential thread feed shaft 206, the differential thread feed shaft 206 is divided into a transmission section and a connecting section that are distributed at intervals, wherein the transmission section is connected to the advance / retract sliding tool holder 207 through a first thread, and optionally, the thread on the transmission section is right-handed, and the connecting section is connected to the support tool holder 208 through a second thread. Optionally, the thread on the connecting section is left-handed; a shift fork is installed at the right end of the differential thread feed shaft 206, and a pit is provided for cooperating with a spring top ball to form an anti-overload top ball structure 210; the support tool holder 208 is close to the left-handed thread portion of the differential thread feed shaft 206, and a recess is provided for cooperating with a spring top ball to form an anti-retraction top ball structure 209; the advance / retract sliding tool holder 207 is placed in the front end cavity of the support tool holder 208, and is restricted by a sliding limit key to only move forward and backward in the key slot of the support tool holder 208.

[0105] Continuing with the above, the shift fork plate includes a fixed ring and a plurality of shifting leaves; the fixed ring is installed on the right end of the differential thread feed shaft 206; one end of the shifting leaf is fixedly connected to the outer wall of the fixed ring, and the other end extends in the radial direction of the fixed ring away from the fixed ring; the plurality of shifting leaves are distributed at intervals along the circumference of the fixed ring.

[0106] When the hydraulic motor 214 is running, the fork piece rotates with the rotary tool rest 203 (assuming it is rotating forward at this time). Every time it passes the blade stop 202, where the blade stop 202 can be designed as a stop block, the moving blade will interfere with the stop block, so that the fork piece drives the differential thread feed shaft 206 to rotate a certain angle, making the differential thread feed shaft 206 advance axially by a left-handed pitch. At the same time, the in / out sliding tool rest 207 rotates right-handed and axially retreats by a left-handed pitch. Here, the different thread pitches and helix directions of the two form a differential relationship, generally causing the cutting tool 205 to advance for cutting. Additionally, it should be added that the limit retaining ring 211 installed on the rotary tool rest 203 can prevent the differential thread feed shaft 206 from axially displacing excessively; when the differential thread feed shaft 206 reaches the position and cannot retreat further, the fork piece and the differential thread feed shaft 206 will rotate relative to each other under the action of the anti-overload ball structure 210, protecting the fork piece from being damaged and completing the retraction of the tool. Under the action of the anti-retraction ball structure 209, the differential thread feed shaft 206 and the support tool rest 208 also rotate relative to each other. It should be noted here that both the anti-overload ball structure 210 and the anti-retraction ball structure 209 belong to the prior art, and their structures and functions are well-known, so no specific elaboration will be made on them.

[0107] When changing the direction of the hydraulic oil in and out of the injection / circulation interface 212 of the two hydraulic motors of the hydraulic motor 214, the rotary tool rest 203 will rotate in reverse. Through the cooperation of the fork piece and the stop block, the differential thread feed shaft 206 will retreat along its axis, and the cutting tool 205 will retreat to complete the tool retraction action. The injection / circulation interface 212 of the hydraulic motor can adopt an insertable self-sealing two-way valve quick connector, which is in an open state when inserted and in a closed state otherwise.

[0108] Regarding the seal suspension assembly 1, specifically:

[0109] Refer to Figure 6 , from top to bottom, the outer cylinder 101 is divided into an upper cylinder, a partition joint 115, and a lower cylinder. The upper end of the upper cylinder and the lower end of the lower cylinder are respectively connected to the flange cylinder housing 201 and the wellhead gas production tree flange. The partition joint 115 serves as an isolation structure between the sealing mechanism and the suspension mechanism, and bears the entire weight of the wellbore velocity string 3. And it is sealed with the upper cylinder and the lower cylinder through sealing rings 116; positioning sealing threads are provided at the upper and lower positions near the flange inside the outer cylinder 101 for installing sealing retaining rings to fix all accessories.

[0110] Refer to Figures 6 to 8, the sealing mechanism includes a first sealing retaining ring 102, a sealing piston sleeve 103, a semi-circular sealing assembly carrier 104, and an annular sealing rubber cylinder assembly 105; there are two first sealing retaining rings 102, which are spaced apart and sleeved on the sealing piston sleeve 103, and are sealed with the outer cylinder 101 and the sealing piston sleeve 103 through sealing rings 116 respectively, and are also threadedly connected to the outer cylinder 101 to enclose a first liquid chamber with the outer wall of the sealing piston sleeve 103 and the inner wall of the outer cylinder 101; along the circumference of the sealing piston sleeve 103, a first boss 106 protrudes from the outer wall of the sealing piston sleeve 103, the first boss 106 abuts against the inner wall of the outer cylinder 101, and a sealing ring 116 is provided between the first boss 106 and the inner wall of the outer cylinder 101 to divide the first liquid chamber into two non-communicating first sub-liquid chambers; two sealing mechanism injection / circulation interfaces 107 are provided on the side wall of the outer cylinder 101 at intervals, and the two sealing mechanism injection / circulation interfaces 107 are respectively communicated with the two first sub-liquid chambers; the semi-circular sealing assembly carrier 104 includes two sub-semi-circular sealing assembly carriers, the two sub-semi-circular sealing assembly carriers are symmetrically distributed and enclose a sealing channel for passing through the velocity string 3; the sealing piston sleeve 103 is sleeved on the semi-circular sealing assembly carrier 104 and is slidably matched with the two sub-semi-circular sealing assembly carriers through a dovetail groove structure, and forms a wedge mechanism with the two sub-semi-circular sealing assembly carriers, and the sealing piston sleeve 103 is also slidably matched with the first sealing retaining ring 102 to drive the first boss 106 to move between the two sealing mechanism injection / circulation interfaces 107 along the axial direction of the outer cylinder 101; the annular sealing rubber cylinder assembly 105 is divided into two sub-rubber cylinders, both of the two sub-rubber cylinders are semi-circular rings and are respectively embedded in the inner walls of the two sub-semi-circular sealing assembly carriers.

[0111] Specifically, taking Figure 6 as an example, liquid is injected into the corresponding first sub-liquid chamber through one of the sealing mechanism injection / circulation interfaces 107, that is, thrust is provided to move the sealing piston sleeve 103 upward or downward. Correspondingly, the two sub-semi-circular sealing assembly carriers move toward or away from each other in the horizontal direction; when the two sub-semi-circular sealing assembly carriers move toward each other, the sub-rubber cylinders are pressed, and the sub-rubber cylinders rely on their elastic deformation to seal the velocity string 3. When the two sub-semi-circular sealing assembly carriers move away from each other, the sub-rubber cylinders are separated from the velocity string 3. It should be added here that the two conical surfaces of the cooperation between the sub-semi-circular sealing assembly carrier and the sealing piston sleeve 103 are designed with a self-locking angle. Without moving the sealing piston sleeve 103, the sealing mechanism maintains the pressing and sealing state of the velocity string 3.

[0112] Refer to Figure 6 and Figures 9 to 12The suspension mechanism includes a second sealing retaining ring 108, a slip piston sleeve 109 and a slip body 110; two second sealing retaining rings 108 are provided, and the two second sealing retaining rings 108 are spaced apart and are both sleeved on the slip piston sleeve 109, and are sealed with the outer cylinder 101 and the slip piston sleeve 109 by a sealing ring 116, and are also threadedly connected to the outer cylinder 101 to enclose the outer wall of the slip piston sleeve 109 and the inner wall of the outer cylinder 101 to form a second liquid-containing cavity; along the circumference of the slip piston sleeve 109, a second boss 111 is protruded on the outer wall of the slip piston sleeve 109, and the second boss 111 is in conflict with the inner wall of the outer cylinder 101, and a sealing ring 116 is provided between the second boss 111 and the inner wall of the outer cylinder 101 to separate the second liquid-containing cavity into two second bosses that are not connected to each other. Sub-liquid chamber; two suspension mechanism injection / circulation interfaces 112 are arranged at intervals on the side wall of the outer cylinder 101, and the two suspension mechanism injection / circulation interfaces 112 are respectively connected to the two second sub-liquid chambers; the cava body 110 includes two sub-cava bodies, the two sub-cava bodies are symmetrically distributed, and enclose a suspension channel for penetrating the velocity column 3, and the inner wall of the sub-cava body is provided with bidirectional cava teeth; the cava piston sleeve 109 is sleeved on the cava body 110, and is slidably matched with the two sub-cava bodies through a dovetail groove structure, and forms an inclined wedge mechanism with the two sub-cava bodies, and the cava piston sleeve 109 is also slidably matched with the second sealing retaining ring 108, so as to drive the second boss 111 to move between the two suspension mechanism injection / circulation interfaces 112 along the axial direction of the outer cylinder 101.

[0113] Specifically, Figure 6 For example, liquid is injected into the corresponding second sub-liquid chamber through one of the injection / circulation interfaces 112 of the suspension mechanism, that is, thrust is provided to move the slip piston sleeve 109 upward or downward, and correspondingly, the two sub-slip bodies move toward or away from each other in the lateral direction; when the two sub-slip bodies move toward each other, the two-way slip teeth engage with the speed column 3 to limit the movement of the speed column 3, and when the two sub-slip bodies move away from each other, the two-way slip teeth separate from the speed column 3. It should be added here that the two conical surfaces matched between the sub-slip body and the slip piston sleeve 109 are designed as self-locking angles, and the slip mechanism maintains the clamping state of the speed column 3 without moving the slip piston sleeve 109.

[0114] It should be added here that the sealing mechanism injection / circulation interface 107 and the suspension mechanism injection / circulation interface 112 are both plug-in type self-sealing bidirectional valve quick connectors, which are in an open state when inserted and in a closed state otherwise. Figure 6A limit stop ring 113 is also threadedly connected inside the outer cylinder 101. Two limit stop rings 113 are provided. The upper limit stop ring 113 is used to prevent the slip piston sleeve 109 from moving downward excessively and the slip body 110 from moving up and down. The lower limit stop ring 113 is used to prevent the sealing piston sleeve 103 from moving upward excessively and the semicircular sealing assembly supporting body 104 from moving up and down.

[0115] refer to Figure 13 The flap gate valve 5 includes a gate valve housing 501, a tongue-shaped gate plate 502 and a reset spring 503; the lower end of the gate valve housing 501 is flange-connected to the oil outlet 4, and the upper end is used to be flange-connected to the coiled tubing blowout preventer; a plurality of sealing rings are provided on the tongue-shaped gate plate 502 for sealing the wellhead pressure, and one side of the tongue-shaped gate plate 502 is hinged to the gate valve housing 501 through a gate plate core shaft 504; the axis of the gate plate core shaft 504 is perpendicular to the axis of the flow passage; optionally, the reset spring 503 is a torsion spring, which is sleeved on the gate plate core shaft 504 and is respectively connected to the gate valve housing 501 and the tongue-shaped gate plate 502, and the reset spring 503 makes the tongue-shaped gate plate 502 have a tendency to rotate around the axis of the gate plate core shaft 504 and in the direction of blocking the flow passage.

[0116] When the velocity string 3 is lowered, the tongue-shaped gate plate 502 compresses the reset spring 503 and swings downward to form a passage through the velocity string 3. When the velocity string 3 is pulled out, the reset spring 503 is reset, forcing the tongue-shaped gate plate 502 to tilt upward and press against the outer shell, and form a seal under the action of the flap seal ring 505. The higher the pressure in the well, the greater the upward force and the better the seal, thereby ensuring that the wellhead fluid flows out of the oil outlet spool 4 in a controlled manner.

[0117] By adopting the above design, without moving the tubing in the well and without killing the well, the velocity string 3 is lowered to the completion position, and the coiled tubing velocity string wellhead device is retained and installed in the well. The velocity string 3 and the coiled tubing velocity string wellhead device act as the completion production string, which can improve the gas, oil and water flow state in the wellbore, so as to achieve the purpose of increasing the gas flow and liquid flow rate, reducing the bottom hole accumulation, reducing the slip loss, and resuming the production of the gas well. In addition, by adopting this design, the wellhead is compactly integrated, and the characteristics of flange connection, large diameter, and no operation window enable the device to withstand higher pressure; with a large tonnage suspension volume, a large-size coiled tubing can be used as the velocity string 3, and operations such as tool casting and flow control can be performed in the velocity string 3; it can operate under pressure, and its superiority is essentially different from the conventional velocity string 3, because there is no need to kill the well, so as to avoid formation pollution, and overcome the cumbersome operations such as the need to induce spray activation after the completion of the conventional velocity string 3; the adjustment and removal of the velocity string 3 are convenient and quick, and there is no need to kill the well.

[0118] The present invention also provides a method for using a coiled tubing velocity string wellhead device. The method is based on the above coiled tubing velocity string wellhead device and comprises the following steps:

[0119] S1: Establish and install the velocity string 3; S101: Connect the coiled tubing velocity string wellhead device to the original wellhead gas (oil) production tree; S102: Lower the velocity string 3 to a predetermined depth; S103: Select the injection / circulation interface 112 of the suspension mechanism to inject liquid into the corresponding second sub-chamber to tighten the two sub-slip bodies, and lock it after confirming the suspension; S104: Select the injection / circulation interface 107 of the sealing mechanism to inject liquid into the corresponding first sub-chamber to tighten the two sub-semicircular sealing assembly carriers, and then conduct a pressure test according to the standard; S105: Select the injection / circulation interface 212 of the corresponding hydraulic motor to inject liquid into the hydraulic motor 214. After the load of the injected hydraulic oil decreases, lift the velocity string 3 to confirm that the velocity string 3 is cut off; S106: Pull out the remaining velocity string 3; S107: Install the surface production process according to the production function, and start production after the pressure test is qualified; S2: Replace or remove the velocity string 3; S201: Lower the coiled tubing plugging and fishing joint with a positive one-way flow function into the coiled tubing velocity string wellhead device and dock it with the velocity string 3 remaining in the wellbore; S202: After the injection head lifts the load to confirm the capture, apply pressure in sequence to open the sealing mechanism and the suspension mechanism; S203: Lift the captured velocity string 3 and the coiled tubing plugging and fishing joint to the ground.

[0120] In the above, in step S103, after the suspension mechanism is seated by hydraulic pressure, the injection head releases the load, tests and verifies the suspension. Observing that the hook load is zero indicates successful suspension; in step S104, during the pressure test, apply pressure from the production gate on the wellhead assembly of the velocity string 3, test and verify its sealing performance. Observing that the pressure does not drop indicates successful suspension sealing.

[0121] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A coiled tubing velocity string wellhead device, characterized in that, Comprising: A sealing and hanging assembly (1), a cutting and releasing assembly (2), an oil outlet four-way (4) and a flap gate valve (5); The sealing and hanging assembly (1) includes an outer cylinder body (101), a sealing mechanism and a hanging mechanism; Both ends of the outer cylinder body (101) are provided with connecting flanges (114) for connecting to the wellhead gas production tree and the cutting and releasing assembly (2) respectively. A partition joint (115) is provided in the middle of the outer cylinder body (101). The partition joint (115) serves as an isolation structure between the sealing mechanism and the hanging mechanism and cooperates with a limit retaining ring (113) threadedly connected to the inner wall of the outer cylinder body (101) to fix the sealing mechanism and the hanging mechanism; The sealing mechanism is arranged inside the outer cylinder body (101) for sealing the annulus formed between the outer cylinder body (101) and the velocity string (3); The hanging mechanism is arranged inside the outer cylinder body (101) for fastening the velocity string (3) to the outer cylinder body (101); The cutting and releasing assembly (2) includes a flange cylinder shell (201), a power mechanism and a cutting mechanism; The flange cylinder shell (201) is in a cylindrical shape, and fixed flanges (216) are respectively provided at both ends thereof for connecting to the oil outlet four-way (4) and the connecting flange (114) of the outer cylinder body (101). A flap stop (202) is provided on the inner wall of the flange cylinder shell (201); The power mechanism is inside the flange cylinder shell (201) and includes a rotary tool rest (203) and a driving assembly. Among them, the rotary tool rest (203) is provided with a receiving channel passing through itself and extending along the axial direction of the flange cylinder shell (201) for passing through the velocity string (3). The driving assembly is fixed to the flange cylinder shell (201) and is in transmission connection with the rotary tool rest (203) to drive the rotary tool rest (203) to rotate forward or backward around the axis of the receiving channel; The cutting mechanism is inside the flange cylinder shell (201) and is arranged on the side wall of the rotary tool rest (203), and includes a fork piece (204), a cutting tool (205) and a transmission assembly; The fork piece (204) is rotationally matched with the rotary tool rest (203) through a rotating shaft and is also in transmission connection with the cutting tool (205) through the transmission assembly. The fork piece (204) can pass through the flap stop (202) under the working conditions of the forward or backward rotation of the rotary tool rest (203) and rotate correspondingly around the axis of the rotating shaft under the blocking of the flap stop (202); The transmission assembly is configured to drive the cutting tool (205) to move in a direction perpendicular to the axis of the flange cylinder shell (201) under the working condition that the fork piece (204) rotates correspondingly around the axis of the rotating shaft, so as to move forward into the receiving channel or retreat out of the receiving channel; The flap gate valve (5) is flange-connected to the oil outlet four-way (4) and is configured to be in an open state when the velocity string (3) is inserted and in a closed state when the velocity string (3) is withdrawn.

2. The coiled tubing velocity string wellhead device according to claim 1, wherein, The transmission assembly comprises a differential thread feed shaft (206) and an advance / retract sliding tool holder (207); A supporting tool holder (208) is fixed to the side wall of the rotating tool holder (203); The differential thread feed shaft (206) constitutes the rotating shaft, and one end of the differential thread feed shaft (206) is provided with two sections of lead screws with different pitches, namely left-handed and right-handed, the left-handed thread cooperates with the thread on the supporting tool holder (208), and the right-handed thread cooperates with the thread on the advancing / retreating sliding tool holder (207), and the other end is used for mounting the shift fork plate (204); The advance / retreat sliding tool holder (207) is slidably matched with the supporting tool holder (208), and the sliding path extends along the axial direction of the differential thread feed shaft (206) and is perpendicular to the axis of the accommodating channel; The cutting knife (205) is fixed to the advancing / retreating sliding knife holder (207).

3. The coiled tubing velocity string wellhead device according to claim 2, wherein, A concave hole is provided at a left-handed threaded portion of the support tool holder (208) close to the differential thread feed shaft (206) for cooperating with a spring top ball to form an anti-retraction top ball structure (209).

4. The coiled tubing velocity string wellhead device according to claim 2, wherein The shift fork piece (204) comprises a fixing ring and a plurality of shifting leaves; The fixing ring is installed at one end of the differential thread feed shaft (206) away from the cutting knife (205), and the inner wall of the fixing ring is matched with the side surface of the differential thread feed shaft (206) via an anti-overload ball structure (210); One end of the moving blade is fixedly connected to the outer wall of the fixing ring, and the other end extends in the radial direction of the fixing ring toward a direction away from the fixing ring; A plurality of the shifting blades are distributed at intervals along the circumference of the fixing ring.

5. The coiled tubing velocity string wellhead device according to claim 2, wherein, The inner wall of the rotating tool holder (203) is provided with a limit ring (211); The limit stop ring (211) is located on the sliding path of the advance / retreat sliding knife holder (207), and can come into contact with the advance / retreat sliding knife holder (207) after the cutting knife (205) has cut the velocity column (3).

6. The coiled tubing velocity string wellhead device according to claim 1, wherein The drive assembly includes a motor hollow shaft / coupling (213) and a hydraulic motor (214); The hydraulic motor (214) injects / circulates hydraulic oil through the hydraulic motor injection / circulation interface (212) to provide power to make the motor hollow shaft / coupling (213) rotate forward or reverse; The motor hollow shaft / coupling (213) is bolted to the rotating tool holder (203).

7. The coiled tubing velocity string wellhead device according to claim 1, characterized in that, The sealing mechanism comprises a first sealing retaining ring (102), a sealing piston sleeve (103), a semicircular sealing assembly supporting body (104) and a semicircular sealing rubber cylinder assembly (105); Two first sealing baffle rings (102) are provided, and the two first sealing baffle rings (102) are spaced apart and are both sleeved on the sealing piston sleeve (103) and threadedly connected to the outer cylinder (101) to enclose the outer wall of the sealing piston sleeve (103) and the inner wall of the outer cylinder (101) to form a first liquid containing cavity; Circumferentially along the sealing piston sleeve (103), a first boss (106) protrudes from the outer wall of the sealing piston sleeve (103), and the first boss (106) abuts against the inner wall of the outer cylinder (101) to divide the first liquid chamber into two non-communicating first sub-liquid chambers; Two sealing mechanism injection / circulation interfaces (107) are provided on the side wall of the outer cylinder (101) and are spaced apart, and the two sealing mechanism injection / circulation interfaces (107) are respectively communicated with the two first sub-liquid chambers; The semi-circular sealing assembly carrier (104) is a semi-circular ring-shaped body, and the two symmetric semi-circular sealing assembly carriers (104) enclose to form an outer seal of the velocity string. A groove is transversely opened at the lower position of each semi-circular sealing assembly carrier (104) to install the semi-circular sealing rubber barrel assembly (105); The outer side of the upper position of each semi-circular sealing assembly carrier (104) is an inclined cone, and a dovetail tapered panel key is provided on the inclined cone; The sealing piston sleeve (103) is sleeved on the semi-circular sealing assembly carrier (104), and its top is provided with an inclined cone that cooperates with the inclined cone of the semi-circular sealing assembly carrier (104). A dovetail tapered panel groove is provided on the inclined cone of the sealing piston sleeve (103) to cooperate with the two dovetail tapered panel keys of the semi-circular sealing assembly carrier (104) respectively; The two conical surfaces of the semi-circular sealing assembly carrier (104) and the sealing piston sleeve (103) are designed with a self-locking angle.

8. The coiled tubing velocity string wellhead device according to claim 1, characterized in that, The suspension mechanism includes a second sealing retaining ring (108), a slip piston sleeve (109) and a slip body (110); There are two second sealing retaining rings (108), and the two second sealing retaining rings (108) are spaced apart and are both sleeved on the slip piston sleeve (109) and are threadedly connected to the outer cylinder (101) to enclose and form a second liquid chamber with the outer wall of the slip piston sleeve (109) and the inner wall of the outer cylinder (101); Circumferentially along the slip piston sleeve (109), a second boss (111) protrudes from the outer wall of the slip piston sleeve (109), and the second boss (111) abuts against the inner wall of the outer cylinder (101) to divide the second liquid chamber into two non-communicating second sub-liquid chambers; Two suspension mechanism injection / circulation interfaces (112) are provided on the side wall of the outer cylinder (101) and are spaced apart, and the two suspension mechanism injection / circulation interfaces (112) are respectively communicated with the two second sub-liquid chambers; The slip body (110) is a two-piece body, and the two symmetric slip bodies (110) enclose to form a velocity string suspension. A two-way slip tooth is provided on the inner surface of each slip body (110) to limit the movement of the velocity string. The outer side of the slip body (110) is an inclined cone, and a dovetail tapered panel key is provided on the inclined cone; The slip piston sleeve (109) is sleeved on the slip body (110), and a sloped cone matching the sloped cone of the slip body (110) is provided at the bottom end thereof, and dovetail cone panel grooves are respectively provided on the sloped cone of the slip piston sleeve (109) to match the dovetail cone panel keys of the slip body (110); The two conical surfaces of the slip piston sleeve (109) and the slip body (110) are designed with self-locking angles.

9. The coiled tubing velocity string wellhead device according to any one of claims 1 to 8, characterized in that, The flap gate valve (5) comprises a gate valve housing (501), a tongue-shaped gate plate (502) and a return spring (503); The gate valve housing (501) is fixedly connected to one end of the oil outlet spool (4) away from the flange cylinder housing (201), and is provided with a flow passage penetrating through the gate valve housing and communicating with the oil outlet spool (4); The tongue-shaped gate plate (502) is arranged in the gate valve housing (501) in a posture of blocking the flow passage, and one side of the tongue-shaped gate plate is hinged to the gate valve housing (501) via a gate plate core shaft (504); The axis of the gate core shaft (504) is perpendicular to the axis of the flow passage; The return spring (503) is sleeved on the gate core shaft (504) and is respectively connected to the gate valve housing (501) and the tongue-shaped gate (502). The return spring (503) enables the tongue-shaped gate (502) to have a tendency to rotate around the axis of the gate core shaft (504) and in a direction to block the flow channel.

10. A method for using a coiled tubing velocity string wellhead device, characterized in that, The coiled tubing velocity string wellhead device according to any one of claims 1 to 9 comprises the following steps: S1: Establish and install velocity string (3); S101: Connect the coiled tubing velocity string wellhead device to the original wellhead gas (oil) tree; S102: lowering the velocity string (3) to a predetermined depth; S103: Select the injection / circulation interface (112) of the suspension mechanism to inject liquid into the corresponding second sub-liquid chamber, so that the two sub-slip bodies (110) are tightened and locked after the suspension is confirmed; S104: Select the sealing mechanism injection / circulation interface (107) to inject liquid into the corresponding first sub-liquid chamber, so that the two sub-semicircular sealing assembly supporting bodies (104) are tightened, and then pressure test is performed according to the standard; S105: Select the corresponding hydraulic motor injection / circulation interface (212) to inject fluid into the hydraulic motor (214), and after the hydraulic oil load is reduced, lift the speed string (3) to confirm that the speed string (3) is cut off; S106: extract the remaining velocity column (3); S107: Install the surface production process according to the production function, and start production after the pressure test is qualified; S2: Replace or remove the velocity string (3); S201: lowering a coiled tubing plug-in fishing joint with a forward single-flow function into a coiled tubing velocity string wellhead device and docking it with the velocity string (3) retained in the wellbore; S202: After the load is lifted on the injection head to confirm the catch, pressure is applied in sequence to open the sealing mechanism and the suspension mechanism; S203: The salvaged velocity string (3) and the coiled tubing are connected to the salvage joint and lifted to the surface.

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