A double-piston composite double-gate blowout preventer and a method for hanging an oil pipe and sealing a wellhead

Abstract

The present invention discloses a double-piston composite double-gate blowout preventer and a method for hanging an oil pipe and sealing a wellhead, comprising a shell, in which a shear full-sealed gate assembly for closing the wellhead after cutting the oil pipe and a hanging semi-sealed gate assembly for hanging the oil pipe and sealing the wellhead are symmetrically installed from top to bottom, the shear full-sealed gate assembly is connected to a first drive device, the hanging semi-sealed gate assembly is connected to a second drive device, the second drive device includes a hanging piston drive mechanism and a semi-sealed piston drive mechanism; the hanging semi-sealed gate assembly includes: a hanging gate body, a semi-sealed front seal and a floating slip are installed in the hanging gate body; the semi-sealed front seal is connected to the semi-sealed piston drive mechanism, and the slip is connected to the hanging piston drive mechanism. The invention can realize that when the hanging gate is closed, the semi-sealed front seal and the floating slip seem to be a whole but have their own division of labor and do not interfere with each other, so as to realize the hanging of the oil pipe and the sealing of the wellhead, and more importantly, the sealing is reliable and not easy to clamp the continuous oil pipe.

Description

Technical Field

[0001] The present invention relates to the technical field of coiled tubing workover operations, and particularly to a double-piston composite double ram preventer and a method for hanging coiled tubing and sealing the wellhead. Background Art

[0002] The coiled tubing preventer is a well control device during coiled tubing operations. Its function is to quickly close the rams hydraulically, seal the wellhead pressure, and prevent blowouts. The conventional coiled tubing preventer consists of four layers of rams, from top to bottom: full-closed ram, shear ram, hanging ram, and half-closed ram. This structure of the preventer is large in volume and high in cost. Subsequently, an ordinary composite double ram preventer emerged, but its high-pressure sealing is unreliable, and the slips are likely to pinch the coiled tubing when the pressure is high. Therefore, this conventional composite double ram preventer has not been widely used in the market. Summary of the Invention

[0003] Aiming at the above defects or deficiencies, the purpose of the present invention is to provide a double-piston composite double ram preventer and a method for hanging coiled tubing and sealing the wellhead, which achieve reliable high-pressure sealing and the slips are not likely to pinch the coiled tubing when the pressure is high.

[0004] To achieve the above purpose, the technical solution of the present invention is as follows:

[0005] A double-piston composite double ram preventer includes a housing. Inside the housing, a shear full-closed ram assembly for closing the wellhead after cutting the tubing and a hanging half-closed ram assembly for hanging the tubing and sealing the wellhead are symmetrically installed from top to bottom. The shear full-closed ram assembly is connected to a first driving device, and the hanging half-closed ram assembly is connected to a second driving device. The second driving device includes a hanging piston driving mechanism and a half-closed piston driving mechanism. The hanging half-closed ram assembly includes a hanging ram body, and a half-closed front seal and floating slips are installed inside the hanging ram body. The half-closed front seal is connected to the half-closed piston driving mechanism, and the floating slips are connected to the hanging piston driving mechanism.

[0006] The hanging half-closed ram assembly further includes a slip push block arranged behind the floating slips.

[0007] The mounting surface of the floating slips has a clearance fit with the half-closed front seal and the hanging ram body, and the floating slips are located above the half-closed front seal. A limit hole is provided on the upper end surface of the floating slips, and a screw is installed in the limit hole. One end of the screw is fixed to the hanging ram body, and the other end is located in the limit hole. The limit hole and the screw have a clearance fit. A slip push block is fixedly connected to the rear side of the floating slips, and a gap is left between the rear end surface of the floating slips and the hanging ram body. The slip push block has a clearance fit with the hanging ram body. The half-closed front seal is fixedly connected to the hanging ram body.

[0008] The second suspension piston driving mechanism includes a second hydraulic cylinder and a suspension piston rod with an inner cavity structure. One end of the suspension piston rod is matched with the second hydraulic cylinder, and the other end is connected to a slip through a slip push block. A hydraulic cylinder cover is installed at the end of the second hydraulic cylinder. The second half-sealing piston driving mechanism includes a half-sealing piston rod, which is connected to a half-sealing front seal through a suspension gate body. The half-sealing piston rod is located inside the cavity of the suspension piston rod. When driving the half-sealing piston rod, one end of the half-sealing piston rod extends out of the inner cavity of the suspension piston rod and is matched with the suspension gate body. The other end of the half-sealing piston rod is connected with a double locking device.

[0009] The double locking device includes a half-sealing cap screw connected to one end of the half-sealing piston rod. A suspension cap screw is sleeved on the half-sealing cap screw. A hand wheel is fixedly connected to the end of the suspension cap screw away from the half-sealing piston rod. The other end of the suspension cap screw is connected with a piston sleeve, and the piston sleeve is sleeved outside the half-sealing piston rod and the half-sealing cap screw. The other end of the piston sleeve is fixedly connected to the end face of the opening of the inner cavity of the suspension piston rod, and the piston sleeve is located inside the hydraulic cylinder cover to form a hydraulic cavity. A through hole is opened on the piston sleeve, and the through hole communicates the cavity of the suspension piston rod with the hydraulic cavity. An external thread of the suspension cap screw is connected with a cap screw seat, and the cap screw seat is fixedly installed on the outside of the hydraulic cylinder cover.

[0010] The suspension piston rod is T-shaped, the inner cavity structure of the suspension piston rod is T-shaped, the half-sealing piston rod is cross-shaped, and the T-shaped inner cavity of the suspension piston rod is matched with the half-sealing piston rod.

[0011] A piston hanger is sleeved on one end of the suspension piston rod close to the suspension gate body. A gate hanger is correspondingly sleeved on the piston hanger. When the piston is closed, the piston hanger and the gate hanger are in contact with the rear end of the suspension gate body.

[0012] The suspension half-sealing gate assembly further includes a second top seal circumferentially installed on the suspension gate body. A limit hole is opened on the upper end face of the slip, and a screw is arranged in the limit hole. One end of the screw is fixed to the suspension gate body, and the other end is located in the limit hole. A sealing groove is opened on the outer wall of the slip push block, and an O-ring is installed in the sealing groove. The half-sealing front seal is fixedly installed on the suspension gate body through a key.

[0013] The shear fully sealed gate assembly includes a left shear gate body and a right shear gate body, and shear blades and seals are installed on the left shear gate body and the right shear gate body. The shear blades include a first shear blade and a second shear blade, and the second shear blade is fixedly installed on the right shear gate body by screws, and the first shear blade is floatingly installed on the left shear gate body by screws, and the screw hole on the first shear blade is matched with the screw clearance; the seal includes a fully sealed front seal installed between the first shear blade and the left shear gate body, and a top seal circumferentially arranged on the left shear gate body and the right shear gate body, and the fully sealed front seal is embedded in the left shear gate body; when the oil pipe is cut off, the right shear gate body and the second shear blade are matched with the left shear gate body for docking and sealing, and the left shear gate body and the first shear blade are matched with the right shear gate body for docking and sealing.

[0014] A double-piston composite double-gate blowout preventer and a method for hanging an oil pipe and sealing a wellhead:

[0015] 1) The suspension piston driving mechanism of the second driving device drives the suspension semi-closed gate assembly to move toward the center;

[0016] 2) The semi-sealed piston driving mechanism pushes the semi-sealed front seal to straighten and clamp the oil pipe first;

[0017] 3) The hydraulic pressure of the suspension piston drive mechanism then pushes the floating slips to further clamp the oil pipe, suspend the oil pipe, and seal the wellhead at the same time;

[0018] 4) When the coiled tubing is operating in the well and an emergency occurs in the well and the tubing needs to be cut and the seal opening needs to be sealed, the first drive device is started to drive the shear full-seal gate assembly to move toward the center of the wellhead and cut the tubing. After the tubing is cut, the shear full-seal gate assembly is matched and docked to seal the wellhead.

[0019] Compared with the prior art, the beneficial effects of the present invention are:

[0020] The present invention provides a double-piston composite double-gate blowout preventer device, in which the power control of the suspended semi-closed gate is a double-piston structure, which pushes the slips to move toward the wellbore under the action of the hydraulic control force; because the semi-closed piston rod is installed in the inner cavity of the suspension piston rod, the hydraulic pressure causes the semi-closed piston rod to drive the semi-closed front seal to first straighten and clamp the oil pipe, and then the hydraulic pressure controls the suspension piston rod to drive the slips to further clamp the oil pipe, suspend and seal the oil pipe, and it looks like a whole but has its own division of labor and does not interfere with each other. At the same time, when the gate is closed, the floating slips are pushed by the slip push block, and the floating design structure of the metal rigid floating slips can avoid floating when the gate is closed. The slip seal will not pinch the oil pipe when the wellhead contacts the oil pipe, and the semi-sealed front seal is pushed by the gate body to compress and seal the oil pipe. When the gate is closed, they do not interfere with each other, so that the wellhead seal is reliable and the continuous oil pipe is not easily pinched. Since the second shear blade on the right shear gate is designed as a fixed blade and the first shear blade on the left shear gate body is designed as a floating blade, the floating blade can continue to compress the full front seal on the rear side after shearing the oil pipe, so that the seal is more reliable. The device of the present invention presses and limits the hanging piston rod and the semi-sealed piston rod through the double locking device of the hanging semi-sealed gate assembly, so as to ensure the continuous good sealing performance when the hanging gate body is closed and clamped.

[0021] The method for hanging the oil pipe and sealing the wellhead of the device of the present invention comprises the following steps: when closing the gate, the semi-sealed piston rod of the semi-sealed piston driving mechanism is used to push the semi-sealed front seal to straighten and clamp the oil pipe first; and then the hanging piston rod of the hanging piston driving mechanism pushes the floating slip to further clamp the oil pipe until the semi-sealed front seal and the slip reach the maximum pressing force under the driving of their respective corresponding pistons, thereby realizing the hanging of the oil pipe and sealing the wellhead at the same time; when the hanging gate body is closed and clamped, they do not interfere with each other; under the effect of well pressure auxiliary sealing, only the semi-sealed front seal will be compressed to increase the sealing force, and the slip will not be compressed, so the sealing is reliable under high well pressure and the continuous oil pipe is not easy to be clamped; when the continuous oil pipe is operating in the well, the well pressure is abnormal and the oil pipe and the seal opening need to be cut, the first driving device is started to drive the shearing full-sealed gate assembly to move toward the center of the wellhead and cut the oil pipe, and after the oil pipe is cut, the floating blade can continue to compress the front seal to make the sealing more reliable. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of the main structure of the device of the present invention;

[0023] Figure 2 It is a schematic diagram of the top view of the structure of the device of the present invention;

[0024] Figure 3 It is a left-side structural schematic diagram of the device of the present invention;

[0025] Figure 4 It is a schematic diagram of the structure of the suspended semi-closed gate assembly of the device of the present invention;

[0026] Figure 5 is a schematic structural view of the shear full-closed ram and components of the device of the present invention;

[0027] Figure 6 is a schematic structural view of the hanging half-closed end cover and components of the device of the present invention.

[0028] In the figure, 1 - housing; 2 - shear full-closed ram assembly; 3 - side flange assembly; 4 - balance valve assembly; 5 - hanging half-closed ram assembly; 6 - ram hanger; 7 - piston hanger; 8 - hanging half-closed end cover; 9 - shear full-closed end cover; 21 - left shear ram body; 22 - right shear ram body; 23 - top seal; 24 - full-closed front seal; 25 - shear blade; 26 - screw; 51 - hanging ram body; 52 - half-closed front seal; 53 - second top seal; 54 - floating slip; 55 - key; 56 - slip push block; 57 - screw; 58 - O-ring; 801 - hanging piston rod; 802 - slide rod hydraulic cylinder; 803 - slide rod; 804 - hydraulic cylinder; 805 - hydraulic cylinder cover; 806 - setscrew seat; 807 - hanging setscrew; 808 - handwheel; 809 - half-closed top screw; 810 - piston sleeve; 811 - half-closed piston rod. Specific embodiments

[0029] The present invention will be described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of them. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0030] As Figure 1As shown in FIGS. 1-6, a double-piston composite double-gate blowout preventer includes a housing 1. Inside the housing 1, a shear full-closed gate assembly 2 for cutting the tubing and closing the wellhead, and a hanging half-closed gate assembly 5 for hanging the tubing and sealing the wellhead are symmetrically installed from top to bottom. The shear full-closed gate assembly 2 is connected to a first driving device and a locking device. The hanging half-closed gate assembly 5 is connected to a second driving device and a double-locking device for pressing and fixing the half-closed piston rod 811 and the hanging piston rod 801. The second driving device includes a hanging piston driving mechanism and a half-closed piston driving mechanism. The hanging half-closed gate assembly 5 includes a hanging gate body 51. Inside the hanging gate body 51, a half-closed front seal 52 and a floating slip 54 are installed. The half-closed front seal 52 is connected to the half-closed piston driving mechanism, and the floating slip 54 is connected to the hanging piston driving mechanism. Preferably, the hanging half-closed gate assembly 5 further includes a slip push block 56 arranged at the rear side of the floating slip 54. It should be noted that the mounting surface of the floating slip 54 has a clearance fit with the half-closed front seal 52 and the hanging gate body 51, and the floating slip 54 is located above the half-closed front seal 52. A limiting hole is provided on the upper end surface of the floating slip 54. A screw 57 is arranged in the limiting hole. One end of the screw 57 is fixed to the hanging gate body 51, and the other end is located in the limiting hole. A slip push block 56 is fixedly connected to the rear side of the floating slip 54, and a clearance is left between the rear end surface of the floating slip 54 and the hanging gate body 51. The slip push block 56 has a clearance fit with the hanging gate body 51. The clamping surface at the front end of the floating slip 54 is granular teeth. The half-closed front seal 52 is fixedly connected to the hanging gate body 51.The suspension semi-closed gate assembly 5 is driven by a double piston structure. In the first stage, due to the structure that the semi-closed piston rod 811 is arranged in the inner cavity of the suspension piston rod 801, and the cross-shaped semi-closed piston rod 811 cooperates with the T-shaped inner cavity of the suspension piston rod 801, the hydraulic end cavity of the suspension piston rod 801 has a gap for the semi-closed piston rod 811 to move. When the hydraulic pressure acts, the hydraulic oil enters the hydraulic oil cavity outside the piston sleeve 810 through the oil path in the hydraulic cylinder cover 805, and then passes through the piston sleeve 810. The through hole on the upper side enters the cavity of the suspension piston rod 801 and acts on the semi-sealed piston rod 811. The semi-sealed piston rod 811 moves first in the suspension piston rod 801. When the end face of the hydraulic end cavity of the suspension piston rod 801 contacts the end face of the semi-sealed piston rod 811, when the suspension piston rod 801 moves in the second hydraulic cylinder 804, the suspension piston rod 801 and the semi-sealed piston rod 811 simultaneously drive the suspension semi-sealed gate assembly 5 to move toward the center. The semi-sealed front seal 52 first straightens and clamps the oil pipe. The second stage Since the semi-sealed front seal 52 is a rubber semi-sealed front seal, the semi-sealed front seal 52 has a certain amount of compression and expansion, and the hydraulic pressure controls the semi-sealed piston rod 811 to drive the semi-sealed front seal 52 to increase the squeezing force on the oil pipe. As well as the design structure of the floating slip 54 in the suspended semi-sealed gate assembly 5, the hydraulic pressure continues to control the suspension piston rod 801 to drive the floating slip 54 to further clamp the oil pipe until the semi-sealed front seal 52 and the floating slip 54 reach the maximum clamping force under the drive of their respective corresponding pistons. Therefore, the double piston drive structure looks like a whole but has its own division of labor and does not interfere with each other. At the same time, when the suspended gate body 51 is closed, the floating slip 54 is driven by the suspended piston drive mechanism through the slip push block 56, and the semi-sealed front seal 52 is driven by the semi-sealed piston rod through the suspended gate body 51. When the suspended gate body 51 is closed, they do not interfere with each other. Under the action of well pressure auxiliary sealing, the semi-sealed front seal 52 is compressed, the sealing pressure is increased, and the floating slip 54 will not be compressed. Therefore, the sealing is reliable under high well pressure and it is not easy to clamp the continuous oil pipe.

[0031] In the present invention, the second suspension piston driving mechanism includes a second hydraulic cylinder 804 and a suspension piston rod 801 with an inner cavity structure, one end of the suspension piston rod 801 cooperates with the second hydraulic cylinder 804, and the other end is connected to the floating cava 54 through the cava push block 56, and the end of the hydraulic cylinder 804 is installed with a hydraulic cylinder cover 805, and a hydraulic oil circuit is arranged in the hydraulic cylinder cover 805; the second semi-sealed piston driving mechanism includes a semi-sealed piston rod 811, the semi-sealed piston rod 811 is connected to the semi-sealed front seal 52 through the suspension gate body 51, and the semi-sealed piston rod 811 is located in the cavity of the suspension piston rod 801. When the semi-sealed piston rod 811 is driven, one end of the semi-sealed piston rod 811 extends out of the inner cavity of the suspension piston rod 801 and cooperates with the suspension gate body 51, and the other end of the semi-sealed piston rod 811 is connected with a double locking device.

[0032] Further, the suspension piston rod 801 is T-shaped, the inner cavity structure of the suspension piston rod 801 is T-shaped, the half-sealing piston rod 811 is cross-shaped, and the T-shaped inner cavity of the suspension piston rod 801 cooperates with the half-sealing piston rod 811. Preferably, a piston hanger 7 is sleeved at one end of the suspension piston rod 801 close to the suspension gate body 51, and a gate hanger 6 is correspondingly sleeved on the piston hanger 7. When the piston is closed, the piston hanger 7 and the gate hanger 6 are in contact with the rear end of the suspension gate body 51.

[0033] In the present invention, the double locking device includes a half-sealing plug 809 connected to one end of the half-sealing piston rod 811. A suspension plug 807 is sleeved on the half-sealing plug 809, and the internal thread of the suspension plug 807 cooperates with the external thread of the half-sealing plug 809. A handwheel 808 is fixedly connected to the end of the suspension plug 807 away from the half-sealing piston rod 811. The other end of the suspension plug 807 is connected to a piston sleeve 810, and the piston sleeve 810 is sleeved on the outer sides of the half-sealing piston rod 811 and the half-sealing plug 809. The other end of the piston sleeve 810 is fixedly connected to the end face of the opening of the inner cavity of the suspension piston rod 801, and the piston sleeve 810 is located inside the hydraulic cylinder cover 805 to form a hydraulic cavity. A through hole is opened on the piston sleeve 810, and the through hole communicates the cavity of the suspension piston rod 801 with the hydraulic cavity; an external thread of the suspension plug 807 is connected to a plug seat 806, and the plug seat 806 is fixedly installed on the outer side of the hydraulic cylinder cover 805. When the suspension piston rod 801 and the half-sealing piston rod 811 reach the maximum pressing force through hydraulic pressure, the handwheel 808 is rotated. The external thread of the suspension plug 807 cooperates with the external thread of the plug seat 806, so that the suspension plug 807 can rotate and feed forward, and the suspension plug 807 acts on the piston sleeve 810, so that the piston sleeve 810 presses and limits the suspension piston rod 801 to achieve locking; the half-sealing plug 809 is rotated by a tool, and the internal thread of the suspension plug 807 cooperates with the internal thread of the half-sealing plug 809, so that the half-sealing plug 809 presses and limits the half-sealing piston rod 811 to achieve locking.

[0034] Preferably, the suspension half-sealing gate assembly 5 further includes a second top seal 53 circumferentially installed on the suspension gate body 51. A sealing groove is opened on the outer wall of the slip push block 56, and an O-ring 58 is installed in the sealing groove; the half-sealing front seal 52 is fixedly installed on the suspension gate body 51 through a key 55.

[0035] In the present invention, the shear full-closed ram assembly 2 includes a left shear ram body 21 and a right shear ram body 22 that cooperate with each other. Shearing blades and seals are installed on both the left shear ram body 21 and the right shear ram body 22, and the seal is a rubber seal. The shearing blade includes a first shearing blade 25 and a second shearing blade 27. The second shearing blade 27 is fixedly installed on the right shear ram body 22 through a screw 26, and the first shearing blade 25 is floatingly installed on the left shear ram body 21 through a screw 26. The screw hole on the first shearing blade 25 is in clearance fit with the screw 26. The first shearing blade 25 is located at the lower end of the second shearing blade 27. The seal includes a full-closed front seal 24 installed between the first shearing blade 25 and the left shear ram body 21, and a top seal 23 circumferentially arranged on the left shear ram body 21 and the right shear ram body 22. The full-closed front seal 24 is installed on the left shear ram body 21 in an inlaid manner. When the left shear ram body 21 and the right shear ram body 22 move towards the center to shear the tubing, the first shearing blade 25 and the second shearing blade 27 slide relative to each other, and their contact surfaces are in close contact. After cutting the tubing, the right shear ram body 22 and the second shearing blade 27 are matched and docked with the left shear ram body 21 for sealing, and the left shear ram body 21 and the first shearing blade 25 are matched and docked with the right shear ram body 22 for sealing. Due to the floating installation structure of the first shearing blade 25, when the first shearing blade 25 is docked and extruded with the right shear ram body 22, a reaction force is applied to the full-closed front seal 24, extruding the full-closed front seal 24, increasing the sealing pressure of the contact surface between the full-closed front seal 24 and the right shear ram body 22, making the seal more reliable. At the same time, it can protect the right shear ram body 22 from being damaged by the first shearing blade 25 and avoid the phenomenon of blade breakage.

[0036] It should be noted that a shear full-closed ram assembly 2 and a hanging half-closed ram assembly 5 are installed in the housing 1. Shear full-closed end caps 9 and hanging half-closed end caps 8 are symmetrically installed on both sides of the housing. Both the shear full-closed end cap 9 and the hanging half-closed end cap 8 are connected to a hydraulic mechanism. The hydraulic mechanism includes a hydraulic cylinder and a piston rod. One end of the piston rod is connected to the hydraulic cylinder, and the other end is connected to the shear full-closed ram assembly 2 or the hanging half-closed ram assembly 5. The hanging half-closed ram assembly 5 includes a hanging ram body 51, a half-closed front seal 52, and a floating slip 54. A slip push block 56 is installed in a matching manner with the floating slip 54. The piston rod cooperating with the hanging half-closed end cap 8 includes a half-closed piston rod 811 for driving the half-closed front seal 52 and a hanging piston rod 801 for driving the floating slip 54. The present invention suspends and seals the tubing. Although it seems as a whole, each part has its own division of labor and does not interfere with each other. The seal is reliable and it is not easy to pinch the coiled tubing.

[0037] Furthermore, the housing 1 is a cuboid with an axial through-hole in the center. Two parallel radial through-holes are radially provided in the housing 1 from top to bottom, and both of the radial through-holes are communicated with the axial through-hole. The inner side of the shear full-closed end cover 9 has a first groove and a first through-hole, and the first groove is communicated with the first through-hole. The inner side of the hanging half-closed end cover 8 has a second groove and a second through-hole, and the second groove is communicated with the second through-hole. The first groove of the shear full-closed end cover 9 and the second groove of the hanging half-closed end cover 8 are respectively communicated with the two radial through-holes of the housing 1. The first groove of the shear full-closed end cover 9 is matched with the shear full-closed gate assembly 2, and the second groove of the hanging half-closed end cover 8 is matched with the hanging half-closed gate assembly 5.

[0038] The first driving device includes a first hydraulic cylinder and a first piston rod. The first piston rod is matched with the first hydraulic cylinder. One end of the first piston rod is connected to the right shear gate body 22 and the left shear gate body 21 of the shear full-closed gate assembly 2 through the first through-hole of the shear full-closed end cover 9. Preferably, a locking device is connected to the other end of the first piston rod. Specifically, the locking device includes a piston rod setscrew threadedly connected to one end of the first piston rod. A setscrew seat is sleeved on the piston rod setscrew, and the setscrew seat is fixedly installed on the outer side of the hydraulic cylinder cover of the first hydraulic cylinder. The first driving device and the second driving device further include a slide bar 803 and a slide bar hydraulic cylinder 802 for guiding. One end of the slide bar hydraulic cylinder 802 on the second driving device is connected to the hanging half-closed end cover 8, and one end of the slide bar hydraulic cylinder 802 on the first driving device is connected to the shear full-closed end cover 9. The other ends of the slide bar hydraulic cylinders 802 are both connected to a hydraulic cylinder cover 805. The slide bar 803 is located in the cavity of the slide bar hydraulic cylinder 802. One end of the slide bar 803 is connected to the hydraulic cylinder cover 805, and the other end passes through the hanging half-closed end cover 8 or the shear full-closed end cover 9 and is connected to the housing 1. The second hydraulic cylinder 804 is located inside the slide bar hydraulic cylinder 802, and the hanging piston rod 801 is located between the grouped second hydraulic cylinders 804.

[0039] In addition, side flange assemblies 3 for pumping in and discharging liquids and balance valve assemblies 4 for balancing the pressures in the upper and lower cavities of the gate are installed on both sides of the device of the present invention. When the coiled tubing is operating in the well and special situations such as abnormal well pressure occur and it is necessary to cut the tubing, the shear gate can be used to cut the tubing, and at the same time, the full-closed gate can be used to seal the well, and the liquid can be pumped into the well through the pipe manifold connected by the side flange. The balance valve assembly 4 is used to open the blowout preventer only after the pressures above and below the gate body are balanced by opening the balance valve when it is necessary to open the blowout preventer.

[0040] The working principle of the present invention:

[0041] The double-piston composite double-gate blowout preventer includes a hanging semi-closed gate assembly 5, a shear full-closed gate assembly 2 and a hanging semi-closed end cap assembly. Among them, the hanging semi-closed gate assembly 5 and the shear full-closed gate assembly 2 are installed in the gate cavity of the shell 1 of the blowout preventer. The hanging semi-closed gate 5 is used to hang the oil pipe and seal the wellhead when there is a continuous oil pipe in the well. The hanging semi-closed front seal and the hanging slip are driven by the slip push block and the gate body respectively. The shear full-closed gate 2 is used to cut the oil pipe and seal the wellhead; the hanging semi-closed end cap assembly is a double piston structure, which pushes the hanging semi-closed gate to move toward the wellbore under the action of the hydraulic control force.

[0042] The housing 1 is installed on the wellhead device through a flange. When the coiled tubing is in operation, the corresponding specification of the hanging semi-sealed gate can be used to seal the well. In the first stage: when the hydraulic pressure acts, the semi-sealed piston rod 811 moves first in the hanging piston rod 801, and then when the hanging piston rod 801 moves in the second hydraulic cylinder 804, the hanging piston rod 801 and the semi-sealed piston rod 811 simultaneously drive the hanging semi-sealed composite gate body 5 to move toward the center, and the semi-sealed front seal 52 firstly straightens and clamps the tubing; in the second stage, the semi-sealed After the squeezing force of the front seal 52 on the oil pipe increases, the hydraulic pressure continues to control the suspension piston rod 801 to drive the floating slip 54 to further clamp the oil pipe until the suspension and the semi-seal reach the maximum clamping force under the drive of their respective corresponding pistons. Therefore, the dual piston drive structure looks like a whole but each has its own division of labor and does not interfere with each other. At the same time, when closing the suspension gate body 51, the slip 54 is driven by the suspension piston drive mechanism through the slip push block 56, and the semi-seal front seal 52 is driven by the semi-seal piston rod mechanism through the suspension gate body 51. The floating slips 52 are compressed under the action of well pressure to increase the sealing pressure, so the sealing is reliable and the coiled tubing is not easy to be clamped under high well pressure. When the coiled tubing is operating in the well, when an abnormal situation occurs in the well and the tubing needs to be cut and the seal is opened, the first drive device is started to control the left shearing ram body 21 and the right shearing ram body 22 of the shearing full-sealing ram assembly 2 to move toward the center of the wellhead at the same time, so that the shear blade 25 To cut the oil pipe, the top seals 23 on the left shear ram body 21 and the right shear ram body 22 are tightly attached to the sealing surface of the ram cavity of the shell 1, and the top seal 23 and the fully sealed front seal 24 work together to achieve sealing and control the wellbore pressure. Since the shear blade 25 on the right shear ram body 22 is designed as a fixed blade and the shear blade 25 on the left shear ram body 21 is designed as a floating blade, the reaction force of the floating blade can continue to squeeze and compress the fully sealed front seal 24 on the rear side after shearing the oil pipe, making the sealing more reliable.

[0043] A double-piston composite double-gate blowout preventer and a method for hanging an oil pipe and sealing a wellhead:

[0044] 1) The suspension piston driving mechanism of the second driving device drives the suspension semi-enclosed gate assembly 5 to move toward the center; specifically, due to the structure that the semi-enclosed piston rod 811 is arranged in the inner cavity of the suspension piston rod 801, when the hydraulic pressure acts, the semi-enclosed piston rod 811 first moves in the suspension piston rod 801, and when the hydraulic end of the semi-enclosed piston rod 811 contacts the end surface of the cavity of the suspension piston rod 801, the other end of the semi-enclosed piston rod 811 extends out of the inner cavity of the suspension piston rod 801 by a certain distance, and then the suspension piston rod 801 and the semi-enclosed piston rod 811 simultaneously drive the suspension semi-enclosed composite gate body 5 to move toward the center;

[0045] 2) The semi-sealed piston rod 811 of the semi-sealed piston driving mechanism pushes the semi-sealed front seal 52 to first straighten and clamp the oil pipe;

[0046] 3) The suspension piston rod 801 of the suspension piston driving mechanism then pushes the floating slip 54 to further clamp the oil pipe until the semi-sealed front seal 52 and the slip 54 reach the maximum clamping force under the drive of their respective corresponding pistons, thereby suspending the oil pipe and sealing the wellhead at the same time;

[0047] 4) When the coiled tubing is operating in the well and an emergency occurs in the well and it is necessary to cut the tubing and seal the wellhead, the first drive device is started to drive the shear full-seal gate assembly 2 to move toward the center of the wellhead and cut the tubing. After the tubing is cut, the reaction force of the floating blade on the shear full-seal gate assembly 2 can continue to squeeze and compress the full front seal 24 on the rear side, making the seal more reliable; at the same time, the floating blade can protect the full front seal 24 from being damaged during the movement toward the center of the wellhead.

[0048] It is obvious to those skilled in the art that the above-mentioned specific examples are only preferred embodiments of the present invention. Therefore, the improvements and changes that may be made by those skilled in the art to certain parts of the present invention still embody the principles of the present invention and achieve the purpose of the present invention, and all belong to the scope of protection of the present invention.

Claims

1. A double-piston composite double-gate blowout preventer, characterized in that, It includes a housing (1). Inside the housing (1), a shear full-closed ram assembly (2) for closing the wellhead after cutting the tubing and a hanging half-closed ram assembly (5) for hanging the tubing and sealing the wellhead are symmetrically installed from top to bottom. The shear full-closed ram assembly (2) is connected to a first driving device, and the hanging half-closed ram assembly (5) is connected to a second driving device. The second driving device includes a hanging piston driving mechanism and a half-closed piston driving mechanism; the hanging half-closed ram assembly (5) includes a hanging ram body (51). Inside the hanging ram body (51), a half-closed front seal (52) and a floating slip (54) are installed; the half-closed front seal (52) is connected to the half-closed piston driving mechanism, and the floating slip (54) is connected to the hanging piston driving mechanism; the mounting surface of the floating slip (54) is in clearance fit with the half-closed front seal (52) and the hanging ram body (51), and the floating slip (54) is located above the half-closed front seal (52). A limiting hole is provided on the upper end surface of the floating slip (54), and a first screw (57) is installed in the limiting hole. One end of the first screw (57) is fixed to the hanging ram body (51), and the other end is located in the limiting hole. The limiting hole is in clearance fit with the first screw (57). A slip push block (56) is fixedly connected to the rear side of the floating slip (54), and a gap is left between the rear end surface of the floating slip (54) and the hanging ram body (51). The slip push block (56) is in clearance fit with the hanging ram body (51); the half-closed front seal (52) is fixedly connected to the hanging ram body (51); the hanging piston driving mechanism includes a second hydraulic cylinder (804) and a hanging piston rod (801) with an inner cavity structure. One end of the hanging piston rod (801) is matched with the second hydraulic cylinder (804), and the other end is connected to the floating slip (54) through the slip push block (56). A hydraulic cylinder cover (805) is installed at the end of the second hydraulic cylinder (804), and a hydraulic oil circuit is provided inside the hydraulic cylinder cover (805); the half-closed piston driving mechanism includes a half-closed piston rod (811). The half-closed piston rod (811) is connected to the half-closed front seal (52) through the hanging ram body (51). The half-closed piston rod (811) is located inside the cavity of the hanging piston rod (801). When the half-closed piston rod (811) is driven, one end of the half-closed piston rod (811) extends out of the inner cavity of the hanging piston rod (801) and is matched with the hanging ram body (51). The other end of the half-closed piston rod (811) is connected to a double-locking device, and the hanging piston rod (801) and the half-closed piston rod (811) are pressed and limited through the double-locking device.

2. The double-piston composite double-gate blowout preventer according to claim 1, characterized in that, The double locking device includes a half-closed cap screw (809) connected to one end of the half-closed piston rod (811). A hanging cap screw (807) is sleeved on the half-closed cap screw (809). A hand wheel (808) is fixedly connected to the end of the hanging cap screw (807) away from the half-closed piston rod (811). The other end of the hanging cap screw (807) is connected to a piston sleeve (810). The piston sleeve (810) is sleeved on the outer sides of the half-closed piston rod (811) and the half-closed cap screw (809). The other end of the piston sleeve (810) is fixedly connected to the end face of the inner cavity opening of the hanging piston rod (801). The piston sleeve (810) is located inside the hydraulic cylinder cover (805) to form a hydraulic cavity. A through hole is formed in the piston sleeve (810), and the through hole communicates the cavity of the hanging piston rod (801) with the hydraulic cavity. An external thread of the hanging cap screw (807) is connected to a cap screw seat (806), and the cap screw seat (806) is fixedly installed on the outer side of the hydraulic cylinder cover (805).

3. A double-piston composite double-gate blowout preventer according to claim 1, characterized in that, The hanging piston rod (801) is T-shaped. The inner cavity structure of the hanging piston rod (801) is T-shaped. The half-closed piston rod (811) is cross-shaped. The T-shaped inner cavity of the hanging piston rod (801) is matched with the half-closed piston rod (811).

4. The double-piston composite double-gate blowout preventer according to claim 1 or 3, characterized in that, A piston hanger (7) is sleeved on one end of the hanging piston rod (801) close to the hanging gate body (51). A gate hanger (6) is sleeved on the piston hanger (7) in a matching manner. When the piston is closed, the piston hanger (7) and the gate hanger (6) are in contact with the rear end of the hanging gate body (51).

5. The double-piston composite double-blade blowout preventer according to claim 1, characterized in that, The hanging half-closed gate assembly (5) further includes a second top seal (53) circumferentially installed on the hanging gate body (51). A sealing groove is formed in the outer wall of the slip push block (56), and an O-ring (58) is installed in the sealing groove. The half-closed front seal (52) is fixedly installed on the hanging gate body (51) through a key (55).

6. The double-piston composite double-gate blowout preventer according to claim 1, characterized in that, The described shearing full-closed ram assembly (2) includes a left shearing ram body (21) and a right shearing ram body (22). Shearing blades and seals are installed on both the left shearing ram body (21) and the right shearing ram body (22). The shearing blades include a first shearing blade (25) and a second shearing blade (27). The second shearing blade (27) is fixedly installed on the right shearing ram body (22) through a second screw (26). The first shearing blade (25) is floatingly installed on the left shearing ram body (21) through the second screw (26). The screw hole on the first shearing blade (25) has a clearance fit with the second screw (26). The seal includes a full-closed front seal (24) installed between the first shearing blade (25) and the left shearing ram body (21), and a top seal (23) circumferentially arranged on the left shearing ram body (21) and the right shearing ram body (22). And the full-closed front seal (24) is installed on the left shearing ram body (21) in an inlaid manner. After the tubing is cut, the right shearing ram body (22) and the second shearing blade (27) are mated and sealed with the left shearing ram body (21), and the left shearing ram body (21) and the first shearing blade (25) are mated and sealed with the right shearing ram body (22).

7. A method for suspending a tubing string and sealing a wellhead of the double-piston composite double-ram blowout preventer according to claim 1: 1) The suspension piston drive mechanism of the second drive device drives the suspension half-closed ram assembly (5) to move towards the center; 2) The half-closed piston drive mechanism pushes the half-closed front seal (52) to first straighten and clamp the tubing string; 3) Then, the hydraulic pressure of the suspension piston drive mechanism pushes the floating slip (54) to further clamp the tubing string, suspend the tubing string, and at the same time seal the wellhead; 4) When coiled tubing is operating in the well and an emergency occurs in the well, when it is necessary to cut the tubing string and seal the wellhead, start the first drive device to drive the shearing full-closed ram assembly (2) to move towards the center of the wellhead, cut the tubing string, and after cutting the tubing string, the shearing full-closed ram assembly (2) is mated and sealed to seal the wellhead.

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