Composite ram assembly for coiled tubing operation and blowout preventer using the same

Abstract

The present disclosure relates to a composite gate assembly for continuous pipe operation and a blowout preventer using the same. The composite gate assembly includes at least a basic insurance structure and an emergency insurance structure, which can realize the semi-sealing, oil pipe hanging, oil pipe cutting and full sealing functions that meet the requirements of continuous pipe operation; the basic insurance structure includes a moving block, a slip plate, a moving block screw and a number of sealing rubber cores; the emergency insurance structure includes a gate body, an emergency V-shaped knife, a V-shaped knife fixing screw and a number of sealing rubber cores; the blowout preventer also includes a blowout preventer shell and two sets of symmetrically distributed side door structures, the side door structure includes a number of cylinder heads, cylinder barrels and pistons; the blowout preventer shell is provided with oil pipe through holes, gate cavity through holes and a number of hydraulic oil interfaces; the composite gate assembly can perform linear motion along the axis in the gate cavity. This type of blowout preventer drives the composite gate assembly by two pairs of hydraulic cylinders, and has only one gate cavity, which can reduce the loss of hydraulic oil and reduce the vertical size of the blowout preventer.

Description

Technical Field

[0001] The present disclosure relates to a blowout preventer, in particular to a wellhead blowout preventer suitable for continuous tubing operation. Background Art

[0002] BOP is a kind of equipment used in drilling operations. It needs to be able to quickly start and shut down the well in case of emergency situations such as overflow, well kick, blowout, etc. to avoid blowout accidents. At present, the gate blowout preventers used in coiled tubing operations are mainly four-gate blowout preventers and composite double-gate blowout preventers, but each of them has some technical problems that need to be solved urgently:

[0003] As shown in document CN212479156U, there is an ultra-high pressure continuous tubing blowout preventer, which is a four-gate blowout preventer. The structural components include: shell, full-sealed gate assembly, shear gate assembly, slip gate assembly, pipe gate assembly, etc.; the full-sealed gate assembly, shear gate assembly, slip gate assembly, and pipe gate assembly are arranged on the shell from top to bottom in sequence; since the gate cavity on the shell needs to cooperate with the gate, the sealing performance requirements are very high, so the processing accuracy of the gate cavity is very high. In addition, the design of the four-layer gate cavity greatly increases the processing cost of the blowout preventer shell; the four pairs of gate assemblies are all equipped with oil cylinders, and the cylinder side door seal and gate locking mechanism are installed on the oil cylinder; this design can realize the four functions required by the continuous pipe operation, but the gate assembly is driven by four pairs of oil cylinders, which greatly increases the consumption of hydraulic oil and has a large energy loss.

[0004] As shown in document CN214886967U, an ultra-high pressure composite function continuous tubing blowout preventer is a double gate blowout preventer, and its structure is as follows: a shear full-sealed gate assembly and a slip half-sealed gate assembly are symmetrically installed from top to bottom in the shell. This blowout preventer shell has two gate cavities; its shear full-sealed gate assembly is connected to a shear hydraulic cylinder assembly, which includes a shear oil cylinder and a hand wheel, one end of the shear oil cylinder is connected to the shear full-sealed gate assembly, and the other end is connected to a series oil cylinder; the slip half-sealed gate assembly is connected to the slip hydraulic cylinder assembly; the two composite gate assemblies are driven by three pairs of oil cylinders, of which two pairs of oil cylinders jointly drive the shear full-sealed gate, and there is still a large consumption of hydraulic oil and energy loss.

[0005] In addition, the common defects of these two types of blowout preventers are: bulky structure and large size, which on the one hand affect the efficiency of on-site operations, and on the other hand also lead to excessively high processing and transportation costs. Summary of the invention

[0006] In order to solve the technical problems existing in the background technology, the present disclosure proposes a composite gate assembly for coiled tubing operation and a blowout preventer using the same. By using the blowout preventer, more than two functions required for coiled tubing operation can be achieved through the composite gate assembly, and the composite gate assembly is driven by only two pairs of hydraulic cylinders. Compared with four-gate and double-gate blowout preventers, the use of hydraulic oil is greatly reduced, the energy loss is reduced, and the blowout preventer housing of the composite gate assembly has only one gate cavity, which reduces the size of the blowout preventer and also greatly reduces the processing cost.

[0007] In a first aspect of the present disclosure, a composite gate assembly for coiled tubing operation is provided, comprising a basic insurance structure and an emergency insurance structure, wherein:

[0008] The composite gate assembly can realize the functions of hanging and cutting the oil pipe required for coiled tubing operations;

[0009] The basic insurance structure includes a moving block, a slip plate and a moving block screw as the main bearing body of the parts;

[0010] A semi-cylindrical groove for placing the slip plate is processed on the moving block; an anti-rotation pin is processed on the cylindrical surface of the semi-cylindrical mounting groove; the anti-rotation pin can cooperate with the anti-rotation pin hole on the outer cylindrical surface of the slip plate to prevent the slip plate from rotating during operation; a second piston matching notch is provided on the bottom surface of the moving block for matching and connecting with the second piston;

[0011] A guide structure is provided on the slip plate to center the oil pipe before the slip plate clamps the oil pipe;

[0012] The motion block screw is screwed in from the bottom of the motion block to fix the position of the slip plate on the motion block;

[0013] The emergency insurance structure includes a gate body as a main bearing body of the parts, an emergency V-shaped knife and a V-shaped knife fixing screw; the middle part of the lower surface of the emergency V-shaped knife lower shear knife is milled, and the size of the notch milled on the lower surface matches the specification of the coiled tubing; the emergency V-shaped knife is fixed to the gate body by the V-shaped knife fixing screw; the bottom surface of the gate body is provided with a first piston matching notch for matching and connecting with the first piston;

[0014] The gate body and the moving block are fitted together through the matching surface of the gate body and the matching surface of the moving block, and the two can slide relatively along the matching surfaces.

[0015] A second aspect of the present disclosure provides a blowout preventer for coiled tubing operations, using the aforementioned composite ram assembly, as well as a blowout preventer housing and two sets of symmetrically distributed side door structures;

[0016] The composite gate assembly forms a pair, which are symmetrically distributed on both sides of the blowout preventer housing;

[0017] The side door structure includes a first cylinder head, a first cylinder barrel, a second cylinder head, a second cylinder barrel, a third cylinder head, a first piston, a second piston and a sealing member;

[0018] The blowout preventer housing is provided with an oil pipe through hole, a gate cavity through hole and four hydraulic oil interfaces, and the oil pipe through hole and the gate cavity through hole are orthogonally distributed; the structural dimensions of the gate cavity through hole match the profile of the composite gate assembly, and the composite gate assembly can perform linear motion along the axis in the gate cavity;

[0019] The first cylinder head, the first cylinder barrel, the second cylinder head, the second cylinder barrel, and the third cylinder head are sequentially arranged from the blowout preventer housing to the outside; the first piston is inserted into the first cylinder barrel, and the two ends of the first piston are respectively connected to the first cylinder head and the second cylinder head; the second piston is inserted into the second cylinder barrel, and the two ends of the second piston are respectively connected to the second cylinder head and the third cylinder head;

[0020] The piston rod diameter of the first piston is twice the piston rod diameter of the second piston, and a through hole is formed on the first piston, and the diameter of the through hole is the same as the piston rod diameter of the second piston;

[0021] The piston rod of the second piston close to the center side of the blowout preventer has a length greater than the sum of the total length of the first piston and the stroke of the basic safety structure;

[0022] A second piston matching structure is provided at the piston rod end of the second piston close to the center side of the blowout preventer. After the piston rod on this side passes through the through hole of the first piston, the second piston matching structure matches with the second piston matching notch of the moving block, so that the second piston is connected to the basic safety structure, and the basic safety structure is driven to move in the gate cavity;

[0023] A first piston matching structure is provided at the end of the piston rod of the first piston close to the center side of the blowout preventer, and the first piston matching structure matches with the first piston matching notch of the gate body, so that the first piston is connected with the emergency insurance structure, and the emergency insurance structure is driven to move in the gate cavity;

[0024] Four hydraulic oil interfaces are provided on the blowout preventer housing. When the first hydraulic oil interface passes hydraulic oil, the first piston is pushed close to the center of the blowout preventer; when the second hydraulic oil interface passes hydraulic oil, the second piston is pushed close to the center of the blowout preventer; when the third hydraulic oil interface passes hydraulic oil, the first piston is pushed away from the center of the blowout preventer; when the fourth hydraulic oil interface passes hydraulic oil, the second piston is pushed away from the center of the blowout preventer.

[0025] Furthermore, the basic insurance structure also includes a first sealing rubber core, a second sealing rubber core, a third sealing rubber core and a sealing rubber core pressing plate;

[0026] The first sealant core is a piece of nitrile rubber embedded in the groove at the bottom of the moving block. The sealant core pressing plate covers the bottom surface of the first sealant core. The sealant core pressing plate is fixed to the moving block by four moving block screws. By controlling the pre-tightening force of the moving block screws, the amount of the pressing plate pressing into the rubber is controlled to extrude the first sealant core, so that the exposed part of the first sealant core is squeezed into a convex curved surface.

[0027] The second sealing rubber core and the third sealing rubber core are used to seal the gaps on the side surface and the top surface of the moving block respectively to form a complete sealing belt.

[0028] Furthermore, the emergency insurance structure also includes a fourth sealing rubber core, a fifth sealing rubber core and a sixth sealing rubber core;

[0029] The fourth sealing rubber core is embedded in the cavity where the emergency V-shaped knife is installed;

[0030] The fifth sealing rubber core and the sixth sealing rubber core are used to seal the gaps on the side and top surfaces of the gate body respectively to form a complete sealing belt;

[0031] After cutting the oil pipe, the emergency V-shaped knife can squeeze the fourth sealing rubber core to achieve full sealing function.

[0032] Furthermore, the blade angle of the emergency V-shaped knife is 90 degrees, and the center of the blade is set to a rounded corner, and the size of the rounded corner matches the specifications of the continuous oil pipe; the middle part of the lower surface of the emergency V-shaped knife lower shear knife is milled, and a V-shaped knife safety groove whose size matches the specifications of the continuous oil pipe is milled on the lower surface.

[0033] The third aspect of the present disclosure provides two methods of applying the aforementioned blowout preventer:

[0034] Method 1 is applicable to the working condition that only the annulus needs to be sealed and the oil pipe does not need to be cut. The working condition 1 includes annulus pressurization or well testing. The method is carried out according to the following steps:

[0035] Connect the second hydraulic oil interface to the hydraulic oil, and connect the other hydraulic oil interfaces to the oil tank, and the pressure is free;

[0036] Driven by the hydraulic oil, the second piston drives the basic safety structure close to the center of the blowout preventer to achieve semi-sealing;

[0037] When the BOP is finished and needs to be opened half-sealed, the fourth hydraulic oil interface is connected to the hydraulic oil, and the other hydraulic oil interfaces are connected to the oil tank, and the pressure is free;

[0038] Driven by the hydraulic oil, the second piston drives the basic safety structure away from the center of the blowout preventer to release the semi-seal.

[0039] Method 2, under the working condition 2 where the oil pipe needs to be hung and the well needs to be sealed after the oil pipe is cut, the working condition 2 includes a blowout, and the following steps are performed:

[0040] Connect the second hydraulic oil interface to the hydraulic oil, and connect the other hydraulic oil interfaces to the oil tank, and the pressure is free;

[0041] The hydraulic oil pushes the second piston to drive the basic safety structure close to the center of the blowout preventer to achieve a closed annular space and suspended oil pipe;

[0042] Make the first hydraulic oil interface and the second hydraulic oil interface pass hydraulic oil, and connect the other hydraulic oil interfaces to the oil tank, and the pressure is free;

[0043] The hydraulic oil pushes the first piston to drive the emergency insurance structure close to the center of the blowout preventer, cutting the oil pipe. The staff then lifts up the cut upper section of the pipe string to completely seal and shut down the well.

[0044] After confirming that the pressure in the well is safe, when the well needs to be opened again, the cut lower section of the pipe string is lifted up;

[0045] Connect the second and third hydraulic oil interfaces to hydraulic oil, and connect the remaining hydraulic oil interfaces to the oil tank, and the pressure is free;

[0046] The second hydraulic oil interface is passed with hydraulic oil to maintain the basic insurance structure to prevent the cut lower section of the oil pipe from falling into the well; the third hydraulic oil interface is passed with hydraulic oil, and the hydraulic oil pushes the first piston to drive the emergency insurance structure away from the center of the blowout preventer to open the full seal;

[0047] Use tools to fix the cut lower section of the oil pipe, so that the fourth hydraulic oil interface is connected to the hydraulic oil, and the remaining hydraulic oil interfaces are connected to the oil tank, and the pressure is free;

[0048] The hydraulic oil pushes the second piston to drive the basic safety structure away from the center of the blowout preventer, thereby releasing the suspension of the oil pipe.

[0049] At least one of the above technical solutions adopted in one or more embodiments of this specification can achieve the following beneficial effects:

[0050] First, the composite gate assembly used in the blowout preventer proposed in the present disclosure can realize more than two functions required for continuous pipe operation, and the blowout preventer housing dedicated to the gate assembly has only one gate cavity, which reduces the vertical size of the blowout preventer while reducing the processing cost, and also greatly reduces the weight of the blowout preventer, reducing the transportation cost and installation cost.

[0051] Secondly, the composite gate assembly used in the blowout preventer proposed in the present disclosure is driven by two pairs of hydraulic cylinders, which reduces the use of hydraulic oil and energy loss compared with the existing four-gate and double-gate blowout preventers. In specific implementation, the hydraulic control pressure requirement can be reduced by increasing the area of ​​the first piston, thereby further reducing energy loss.

[0052] Thirdly, the blowout preventer provided in the present invention has strong structural applicability and can realize more than two functions required for continuous pipe operation. The internal functional components can be combined arbitrarily with a high degree of freedom and can be used in conjunction with other well control equipment with different functions.

[0053] In addition, the first sealant core in the blowout preventer basic safety structure provided by the present invention has a lower processing accuracy requirement for the sealant core after adopting an optimized implementation method of adding a sealant core pressure plate and adjusting the preload force by screws, thereby reducing the manufacturing cost and improving the sealing accuracy.

[0054] It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the disclosure.

[0055] Further features and aspects of the present disclosure will become apparent from the following detailed description of exemplary embodiments with reference to the attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] The drawings herein are incorporated into the specification and constitute a part of the specification. These drawings illustrate embodiments consistent with the present disclosure and are used to illustrate the technical solutions of the present disclosure together with the specification.

[0057] Figure 1 It is a schematic diagram of the structure of the composite gate described in the present invention.

[0058] Figure 2 This is an exploded view of the emergency safety structure described in the present disclosure.

[0059] Figure 3 It is a bottom and side view of the emergency safety structure described in the present disclosure.

[0060] Figure 4 It is a schematic diagram of partial milling of the bottom surface of the emergency V-shaped knife in the emergency safety structure disclosed in the present invention.

[0061] Figure 5 It is an exploded view of the basic safety structure described in the present disclosure.

[0062] Figure 6 It is a bottom side view of the basic safety structure described in the present disclosure.

[0063] Figure 7 It is a quarter-cut perspective view of the blowout preventer disclosed in the present invention.

[0064] Figure 8 It is a cutaway view of a side door of the blowout preventer disclosed in the present invention.

[0065] Fig. 9 It is a partial cutaway view of the blowout preventer disclosed in the present invention.

[0066] Fig.10 It is a front view of the blowout preventer disclosed in the present invention.

[0067] Fig.11 It is a schematic diagram of the cross-sectional structure of the blowout preventer disclosed in the present invention along the AA direction.

[0068] Fig.12 It is a schematic diagram of the cross-sectional structure of the blowout preventer disclosed in the present invention in the BB direction.

[0069] In the figure, 1- BOP housing, 101- first hydraulic oil interface, 102- second hydraulic oil interface, 103- third hydraulic oil interface, 104- fourth hydraulic oil interface, 2- emergency insurance structure, 201- gate body, 202- emergency V-shaped knife, 203- V-shaped knife fixing screw, 204- fourth sealing rubber core, 205- fifth sealing rubber core, 206- sixth sealing rubber core, 207- gate body matching surface, 208- first piston matching notch, 209- V-shaped knife safety groove, 3- basic insurance structure, 301- moving block, 302- slip tooth plate, 303-movement block screw, 304-first sealing rubber core, 305-second sealing rubber core, 306-third sealing rubber core, 307-sealing rubber core pressure plate, 308-guide structure, 309-anti-rotation pin, 310-movement block matching surface, 311-second piston matching groove, 4-side door structure, 401-first cylinder head, 402-first cylinder barrel, 403-second cylinder head, 404-second cylinder barrel, 405-third cylinder head, 406-first piston, 407-second piston, 408-first piston matching structure, 409-second piston matching structure. DETAILED DESCRIPTION

[0070] Various exemplary embodiments, features and aspects of the present disclosure will be described in detail below with reference to the accompanying drawings. The same reference numerals in the accompanying drawings represent elements with the same or similar functions. Although various aspects of the embodiments are shown in the accompanying drawings, the drawings are not necessarily drawn to scale unless otherwise specified.

[0071] In addition, in order to better illustrate the present disclosure, numerous specific details are given in the following specific embodiments. It should be understood by those skilled in the art that the present disclosure can also be implemented without certain specific details. In some examples, methods and means well known to those skilled in the art are not described in detail in order to highlight the main purpose of the present disclosure.

[0072] First, the composite gate assembly used in the specific implementation of the present disclosure is introduced, which can realize two functions required for continuous tubing operations: hanging the oil pipe and cutting the oil pipe.

[0073] like Figure 1 As shown, the composite gate assembly includes a basic safety structure 3 and an emergency safety structure 2. The basic safety structure 3 includes a moving block 301, a slip plate 302, and a moving block screw 303; the emergency safety structure 2 includes a gate body 201, an emergency V-shaped knife 202, and a V-shaped knife fixing screw 203.

[0074] like Figure 5 As shown, in the basic insurance structure 3, the moving block 301 is the main carrier of the remaining parts, which are installed on the moving block 301 and move with the moving block 301; Figure 2 As shown, in the emergency insurance structure 2, the gate body 201 is the main carrier of the remaining parts, which are installed on the gate body 201 and move with the gate body 201; Figure 3 and Figure 5 As shown, the gate body 201 and the moving block 301 are attached together through the gate body matching surface 207 and the moving block matching surface 310, and the two can slide relative to each other along the matching surface; in addition, as shown Figure 3 As shown, the bottom surface of the gate body 201 is also processed with a first piston matching groove 208 for connecting with the first piston 406. Figure 6 As shown, the bottom surface of the moving block 301 is processed with a second piston matching groove 311 for matching with the second piston 407 .

[0075] like Figure 5 As shown, a semi-cylindrical groove for placing the slip plate 302 is processed on the motion block 301, and an anti-rotation pin 309 is processed on the cylindrical surface of the semi-cylindrical mounting groove, which cooperates with the anti-rotation pin hole on the outer cylindrical surface of the slip plate 302 to prevent the slip plate 302 from rotating during operation; a guide structure 308 is also designed and processed on the slip plate 302, which is used to center the oil pipe before the slip plate 302 clamps the oil pipe. The motion block screw 303 is screwed in from the bottom of the motion block 301 to fix the position of the slip plate 302 on the motion block 301.

[0076] like Figure 2 and Figure 4As shown, the blade angle of the emergency V-shaped knife 202 is 90 degrees, and a fillet is set at the center of the blade, and the size of the fillet matches the specification of the continuous oil pipe; the middle part of the lower surface of the shear knife under the emergency V-shaped knife 202 is milled, and a V-shaped knife safety groove 209 whose size matches the specification of the continuous oil pipe is milled on the lower surface, so as to avoid that when the oil pipe is cut, the emergency V-shaped knife 202 is close to the slip plate 302, which causes the oil pipe to deform and exerts too much force on the slip plate 302, resulting in suspension failure and danger; the remaining thickness of the milled part should be able to ensure the strength and durability of the emergency V-shaped knife 202; the emergency V-shaped knife 202 is fixed to the gate body 201 by the V-shaped knife fixing screw 203, and the split design facilitates the replacement of the emergency V-shaped knife 202.

[0077] like Figure 7 As shown, the blowout preventer dedicated to the composite gate assembly can drive the composite gate assembly to independently realize the two functions, and the oil pipe needs to be hung first and then cut off; the composition of the blowout preventer dedicated to the composite gate assembly includes a blowout preventer housing 1 and two sets of symmetrically distributed side door structures 4, and the side door structure 4 includes a first cylinder head 401, a first cylinder barrel 402, a second cylinder head 403, a second cylinder barrel 404, a third cylinder head 405, a first piston 406, a second piston 407 and various sealing components.

[0078] The blowout preventer housing 1 is provided with an oil pipe through hole, a gate cavity through hole and four hydraulic oil interfaces, and the oil pipe through hole and the gate cavity through hole are orthogonally distributed; the structural dimensions of the gate cavity through hole match the profile of the composite gate assembly, and the composite gate assembly performs linear motion along the axis in the gate cavity.

[0079] like Figure 7 As shown, the first cylinder head 401, the first cylinder barrel 402, the second cylinder head 403, the second cylinder barrel 404, and the third cylinder head 405 are sequentially distributed from the blowout preventer housing 1 to the outside; the first piston 406 is inserted into the first cylinder barrel 402, and the two ends of the first piston 406 are respectively connected to the first cylinder head 401 and the second cylinder head 403; the second piston 407 is inserted into the second cylinder barrel 404, and the two ends of the second piston 407 are respectively connected to the second cylinder head 403 and the third cylinder head 405;

[0080] like Figure 8 and Fig. 9As shown, the piston rod diameter of the first piston 406 is twice the piston rod diameter of the second piston 407. The first piston 406 is provided with a through hole, and the diameter of the through hole is the same as the piston rod diameter of the second piston 407. The piston rod of the second piston 407, which is close to the center of the blowout preventer, has a length greater than the sum of the total length of the first piston 406 and the stroke of the basic safety structure 3. The stroke of the basic safety structure 3 varies with the specifications of the coiled tubing. The piston rod end of the second piston 407, which is close to the center of the blowout preventer, is processed with a second piston matching structure 409. The piston rod of this side passes through the first After the through hole of the piston 406 is formed, the second piston matching structure 409 matches with the second piston matching notch 311 of the moving block 301, so that the second piston 407 is connected to the basic insurance structure 3, and the basic insurance structure 3 is driven to move in the gate cavity; the piston rod end of the first piston 406 close to the center side of the blowout preventer is processed with a first piston matching structure 408, and the first piston matching structure 408 matches with the first piston matching notch 208 of the gate body 201, so that the first piston 406 is connected to the emergency insurance structure 2, and the emergency insurance structure 2 is driven to move in the gate cavity;

[0081] The blowout preventer housing 1 is provided with four hydraulic oil interfaces, such as Fig.11 As shown, when the first hydraulic oil interface 101 passes through hydraulic oil, the first piston 406 can be pushed close to the center of the blowout preventer, and when the second hydraulic oil interface 102 passes through hydraulic oil, the second piston 407 can be pushed close to the center of the blowout preventer; Fig.12 As shown, when the third hydraulic oil interface 103 passes through hydraulic oil, the first piston 406 can be pushed away from the center of the blowout preventer, and when the fourth hydraulic oil interface 104 passes through hydraulic oil, the second piston 407 can be pushed away from the center of the blowout preventer.

[0082] By using the composite gate assembly, in an emergency, the basic safety structure 3 can be used to suspend the oil pipe, and the emergency safety structure 2 can be used to cut the oil pipe to ensure the safety of the operation.

[0083] Furthermore, on the basis of the basic solution, a first sealing rubber core 304, a second sealing rubber core 305 and a third sealing rubber core 306 are added to the composite gate assembly to obtain an optimized solution 1:

[0084] The composite gate assembly adds a third function on the basis of the basic solution: a semi-sealing function. The optimized basic insurance structure 3 includes: a moving block 301, a slip plate 302, a moving block screw 303, a first sealing rubber core 304, a second sealing rubber core 305, a third sealing rubber core 306 and a sealing rubber core pressure plate 307.

[0085] like Figure 5As shown, the first sealant core 304 is a piece of nitrile rubber cut into a certain shape and embedded in the groove at the bottom of the moving block 301. The sealant core pressing plate 307 covers the bottom surface of the first sealant core 304. The sealant core pressing plate 307 is fixed to the moving block 301 by four moving block screws 303. By controlling the pre-tightening force of the moving block screws 303, the amount of the sealant core pressing plate 307 pressed into the first sealant core 304 is controlled to extrude the first sealant core 304, so that the exposed part of the first sealant core 304 is squeezed into a convex curved surface, overcoming the problem of low processing precision of nitrile rubber, making the closed annular space more reliable. The second sealant core 305 and the third sealant core 306 respectively seal the gaps on the side and top of the moving block 301 to form a complete sealing belt.

[0086] After adding the first sealing rubber core 304, the second sealing rubber core 305 and the third sealing rubber core 306, when the basic insurance structure 3 is used alone, it has a semi-sealing function, and can seal the annulus when there is a coiled tubing in the blowout preventer; if the pressure in the well cannot be controlled, the emergency insurance structure 2 can also be used to cut the tubing; at this time, the slip plate 302 of the basic insurance structure 3 clamps the tubing to play the role of hanging the tubing.

[0087] Further, on the basis of the optimization scheme 1, a fourth sealing rubber core 204, a fifth sealing rubber core 205 and a sixth sealing rubber core 206 are added to the composite gate assembly to obtain the optimization scheme 2:

[0088] The composite gate assembly adds a fourth function: full sealing function, based on the optimization scheme 1. The optimized emergency insurance structure 2 includes: a gate body 201, an emergency V-shaped knife 202, a V-shaped knife fixing screw 203, a fourth sealing rubber core 204, a fifth sealing rubber core 205 and a sixth sealing rubber core 206.

[0089] like Figure 2 As shown, the fourth sealing rubber core 204 is embedded in the cavity where the emergency V-shaped knife 202 is installed. After the emergency V-shaped knife 202 cuts the oil pipe, it squeezes the fourth sealing rubber core 204 on the opposite side; and the fifth sealing rubber core 205 and the sixth sealing rubber core 206 respectively seal the gaps on the side and top surfaces of the gate body 201 to form a complete sealing belt.

[0090] After adding the fourth sealing rubber core 204, the fifth sealing rubber core 205 and the sixth sealing rubber core 206, when the emergency insurance structure 2 is used, after the oil pipe is cut, the emergency V-shaped knife 202 squeezes the fourth sealing rubber core 204 to achieve a full sealing function.

[0091] Furthermore, based on the optimization scheme 2, the diameters of the first piston 406 and the first cylinder 402 are increased to obtain the optimization scheme 3:

[0092] Since the piston rod diameter of the first piston 406 is twice the piston rod diameter of the second piston 407, and the use of the emergency safety structure 2 requires a larger hydraulic thrust, it is considered to increase the diameter of the first piston 406 and the first cylinder 402 so that when using the same hydraulic control pressure as the second piston 407, the first piston 406 can still have a thrust that is more than twice that of the second piston 407, thereby more reliably realizing the function of the emergency safety structure 2.

[0093] In specific implementation, the blade angle of the emergency V-shaped knife 202 is 90 degrees, and a fillet is set at the center of the blade, and the size of the fillet matches the specification of the coiled tubing; in addition, the middle part of the lower surface of the shearing knife under the emergency V-shaped knife 202 is milled, and a V-shaped knife safety groove 209 whose size matches the specification of the coiled tubing is milled on the lower surface, thereby avoiding that when the oil pipe is cut, the emergency V-shaped knife 202 is close to the slip tooth plate 302, which causes the oil pipe to deform and exerts too much force on the slip tooth plate 302, resulting in suspension failure. The remaining thickness of the milled part should be able to ensure the strength and durability of the emergency V-shaped knife 202; taking a 2-inch coiled tubing as an example, the blade angle of the emergency V-shaped knife 202 is 90 degrees, the radius of the blade center fillet should be 30mm, the milling width of the V-shaped knife safety groove 209 should be 65mm, and the milling remaining thickness should be above 10mm; the emergency V-shaped knife 202 is fixed to the gate body 201 by the V-shaped knife fixing screws 203, and the split design facilitates the replacement of the emergency V-shaped knife 202.

[0094] Since the piston rod diameter of the first piston 406 is twice the piston rod diameter of the second piston 407, and the use of the emergency safety structure 2 requires a larger hydraulic thrust, it is considered to increase the diameter of the first piston 406 and the first cylinder 402 so that when using the same hydraulic control pressure as the second piston 407, the first piston 406 can still have a thrust that is more than twice that of the second piston 407, and the function of the emergency safety structure 2 can be more reliably realized.

[0095] like Fig.11 As shown, after optimization, the diameter D1 of the first piston is 1.26 times the diameter D2 of the second piston.

[0096] The following introduces the working process and control method of the composite gate assembly and the blowout preventer using the composite gate assembly based on the two working conditions of the blowout preventer.

[0097] The first working condition of the BOP requires a closed annulus without cutting the tubing, such as annulus pressurization and well testing. In this condition, only the basic insurance structure 3 is required.

[0098] In this working condition, the first step requires the second hydraulic oil interface 102 to pass hydraulic oil, and the other hydraulic oil interfaces are connected to the oil tank, and the pressure is free; driven by the hydraulic oil, the second piston 407 drives the basic safety structure 3 to approach the center of the blowout preventer to achieve a semi-sealed function;

[0099] The second step of this working condition is that the BOP is completed and the semi-seal needs to be opened; at this time, the fourth hydraulic oil interface 104 needs to be connected to the hydraulic oil, and the other hydraulic oil interfaces are connected to the oil tank, and the pressure is free; under the push of the hydraulic oil, the second piston 407 drives the basic safety structure 3 away from the center of the BOP to release the semi-seal.

[0100] The second working condition of the blowout preventer is an emergency situation where the oil pipe needs to be hung, cut and sealed, such as when a blowout is about to occur; in this condition, the basic insurance structure 3 needs to be used first, and then the emergency insurance structure 2.

[0101] In this working condition, the first step requires that the second hydraulic oil interface 102 is connected to the hydraulic oil, and the other hydraulic oil interfaces are connected to the oil tank, and the pressure is free; the hydraulic oil pushes the second piston 407 to drive the basic safety structure 3 close to the center of the blowout preventer to achieve a closed annulus and suspended oil pipe.

[0102] In this working condition, the second step requires that the first hydraulic oil interface 101 and the second hydraulic oil interface 102 are connected to hydraulic oil, and the other hydraulic oil interfaces are connected to the oil tank, and the pressure is free; the hydraulic oil pushes the first piston 406 to drive the emergency insurance structure 2 close to the center of the blowout preventer, cuts the oil pipe, and the staff lifts up the cut upper section of the pipe string to completely seal and shut down the well.

[0103] After the first two steps are completed, the blowout preventer is fully sealed and shut down. After confirming that the pressure in the well is safe, the oil well needs to be opened again and the cut lower section of the pipe string needs to be lifted up.

[0104] The third step of this working condition requires that the second hydraulic oil interface 102 and the third hydraulic oil interface 103 are connected to hydraulic oil, and the other hydraulic oil interfaces are connected to the oil tank, and the pressure is free; the purpose of the second hydraulic oil interface 102 being connected to hydraulic oil is to maintain the basic insurance structure 3 to prevent the cut lower section of the oil pipe from falling into the well; the third hydraulic oil interface 103 is connected to hydraulic oil, and the hydraulic oil pushes the first piston 406 to drive the emergency insurance structure 2 away from the center of the blowout preventer to open the full seal.

[0105] The last step of this working condition requires the on-site staff to use a specific tool to fix the cut lower section of the oil pipe, and then release the suspension of the oil pipe; this step requires the fourth hydraulic oil interface 104 to pass hydraulic oil, and the other hydraulic oil interfaces to be connected to the oil tank, and the pressure is free; the hydraulic oil pushes the second piston 407 to drive the basic safety structure 3 away from the center of the blowout preventer, and releases the suspension of the oil pipe.

Claims

1. A composite gate assembly for coiled tubing operation, comprising a basic safety structure (3) and an emergency safety structure (2), characterized in that: The composite gate assembly can realize the functions of hanging and cutting the oil pipe required for coiled tubing operations; The basic safety structure (3) comprises a moving block (301) as a main bearing body of the parts, a slip plate (302) and a moving block screw (303); A semi-cylindrical groove for accommodating the slip plate (302) is processed on the moving block (301); an anti-rotation pin (309) is processed on the cylindrical surface of the semi-cylindrical groove; the anti-rotation pin can cooperate with the anti-rotation pin hole on the outer cylindrical surface of the slip plate (302) to prevent the slip plate (302) from rotating during operation; a second piston matching notch (311) is provided on the bottom surface of the moving block (301) for matching and connecting with the second piston (407); A guide structure (308) is provided on the slip plate (302) for centering the oil pipe before the slip plate (302) clamps the oil pipe; The moving block screw (303) is screwed into the bottom of the moving block (301) to fix the position of the slip plate (302) on the moving block (301); The emergency safety structure (2) comprises a gate body (201) as a main bearing body of the parts, an emergency V-shaped knife (202) and a V-shaped knife fixing screw (203); the middle part of the lower surface of the shearing knife under the emergency V-shaped knife (202) is milled, and the size of the notch milled on the lower surface matches the specification of the coiled tubing; the emergency V-shaped knife (202) is fixed to the gate body (201) by the V-shaped knife fixing screw (203); the bottom surface of the gate body (201) is provided with a first piston matching notch (208) for matching and connecting with the first piston (406); The gate body (201) and the moving block (301) are fitted together via a gate body mating surface (207) and a moving block mating surface (310), and the two can slide relative to each other along the mating surfaces.

2. A blowout preventer for coiled tubing operation, using the composite gate assembly according to claim 1, characterized in that: The blowout preventer also includes a blowout preventer housing (1) and two sets of symmetrically distributed side door structures (4); The composite gate assembly forms a pair, which are symmetrically distributed on both sides of the blowout preventer housing (1); The side door structure comprises a first cylinder head (401), a first cylinder barrel (402), a second cylinder head (403), a second cylinder barrel (404), a third cylinder head (405), a first piston (406), a second piston (407) and a sealing member; The blowout preventer housing (1) is provided with an oil pipe through hole, a gate cavity through hole and four hydraulic oil interfaces, the oil pipe through hole and the gate cavity through hole are orthogonally distributed; the structural dimensions of the gate cavity through hole match the profile of the composite gate assembly, and the composite gate assembly can perform linear motion along the axis in the gate cavity; The first cylinder head (401), the first cylinder barrel (402), the second cylinder head (403), the second cylinder barrel (404), and the third cylinder head (405) are sequentially arranged from the blowout preventer housing (1) to the outside; the first piston (406) is inserted into the first cylinder barrel (402), and the two ends of the first piston (406) are respectively connected to the first cylinder head (401) and the second cylinder head (403); the second piston (407) is inserted into the second cylinder barrel (404), and the two ends of the second piston (407) are respectively connected to the second cylinder head (403) and the third cylinder head (405); The piston rod diameter of the first piston (406) is twice the piston rod diameter of the second piston (407), and a through hole is formed on the first piston (406), and the diameter of the through hole is the same as the piston rod diameter of the second piston (407); The piston rod of the second piston (407) close to the center side of the blowout preventer has a length greater than the sum of the total length of the first piston (406) and the stroke of the basic safety structure (3); A second piston matching structure (409) is provided at the piston rod end of the second piston (407) close to the center side of the blowout preventer. After the piston rod on this side passes through the through hole of the first piston (406), the second piston matching structure (409) matches with the second piston matching notch (311) of the moving block (301), so that the second piston (407) is connected to the basic safety structure (3), and the basic safety structure (3) is driven to move in the gate cavity; A first piston matching structure (408) is provided at the end of the piston rod of the first piston (406) close to the center side of the blowout preventer, and the first piston matching structure (408) matches with the first piston matching notch (208) of the gate body (201), so that the first piston (406) is connected to the emergency safety structure (2), and the emergency safety structure (2) is driven to move in the gate cavity; The blowout preventer housing (1) is provided with four hydraulic oil interfaces, wherein when the first hydraulic oil interface (101) passes hydraulic oil, the first piston (406) is pushed close to the center of the blowout preventer, and when the second hydraulic oil interface (102) passes hydraulic oil, the second piston (407) is pushed close to the center of the blowout preventer; when the third hydraulic oil interface (103) passes hydraulic oil, the first piston (406) is pushed away from the center of the blowout preventer, and when the fourth hydraulic oil interface (104) passes hydraulic oil, the second piston (407) is pushed away from the center of the blowout preventer.

3. A blowout preventer for coiled tubing operation according to claim 2, characterized in that: The basic insurance structure (3) further comprises a first sealing rubber core (304), a second sealing rubber core (305), a third sealing rubber core (306) and a sealing rubber core pressing plate (307); The first sealing rubber core (304) is a piece of nitrile rubber embedded in the groove at the bottom of the moving block (301). The sealing rubber core pressing plate (307) covers the bottom surface of the first sealing rubber core (304). The sealing rubber core pressing plate (307) is fixed to the moving block (301) by four moving block screws (303). By controlling the pre-tightening force of the moving block screws (303), the amount of the pressing plate pressing into the rubber is controlled to extrude the first sealing rubber core (304), so that the exposed portion of the first sealing rubber core (304) is squeezed into a convex curved surface; The second sealing rubber core (305) and the third sealing rubber core (306) are used to seal the gaps on the side and top surfaces of the moving block (301) respectively, so as to form a complete sealing belt.

4. A blowout preventer for coiled tubing operation according to claim 3, characterized in that: The emergency insurance structure (2) further comprises a fourth sealing rubber core (204), a fifth sealing rubber core (205) and a sixth sealing rubber core (206); The fourth sealing rubber core (204) is embedded in the cavity where the emergency V-shaped knife (202) is installed; The fifth sealing rubber core (205) and the sixth sealing rubber core (206) are used to seal the gaps on the side and top surfaces of the gate body (201) respectively, so as to form a complete sealing belt; After the oil pipe is cut, the emergency V-shaped knife (202) can squeeze the fourth sealing rubber core (204) to achieve a full sealing function.

5. A blowout preventer for coiled tubing operation according to claim 4, characterized in that: The blade angle of the emergency V-shaped knife is 90 degrees, and the center of the blade is set to be rounded, and the size of the rounded corner matches the specification of the coiled tubing; the middle part of the lower surface of the lower shear knife of the emergency V-shaped knife (202) is milled to mill a V-shaped knife safety groove (209) on the lower surface with a size matching the specification of the coiled tubing.

6. A blowout preventer for coiled tubing operation according to claim 5, characterized in that: The diameter of the first piston (406) is 1.26 times the diameter of the second piston (407).

7. A method for using any one of claims 3 to 6 of the blowout preventer, in a working condition where only the annulus needs to be sealed and the oil pipe does not need to be cut, wherein the working condition includes annulus pressurization or well testing, and the method is performed according to the following steps: The second hydraulic oil interface (102) is connected to hydraulic oil, and the other hydraulic oil interfaces are connected to the oil tank, and the pressure is free; Under the push of hydraulic oil, the second piston (407) drives the basic safety structure (3) close to the center of the blowout preventer to achieve semi-sealing; When the blowout preventer is finished and needs to be semi-sealed, the fourth hydraulic oil interface (104) is connected to hydraulic oil, and the other hydraulic oil interfaces are connected to the oil tank, and the pressure is free; Under the push of the hydraulic oil, the second piston (407) drives the basic safety structure (3) away from the center of the blowout preventer, thereby releasing the semi-seal.

8. A method for using any one of the blowout preventers of claims 4 to 6, in a second working condition where the oil pipe needs to be hung and the well needs to be sealed after the oil pipe is cut, wherein the second working condition includes a blowout, and the method is performed according to the following steps: The second hydraulic oil interface (102) is connected to hydraulic oil, and the other hydraulic oil interfaces are connected to the oil tank, and the pressure is free; The hydraulic oil pushes the second piston (407) to drive the basic safety structure (3) close to the center of the blowout preventer, thereby achieving a closed annular space and hanging the oil pipe; The first hydraulic oil interface (101) and the second hydraulic oil interface (102) are connected to hydraulic oil, and the other hydraulic oil interfaces are connected to the oil tank, and the pressure is free; The hydraulic oil pushes the first piston (406) to drive the emergency safety structure (2) close to the center of the blowout preventer, shearing the oil pipe, and the staff lifts up the sheared upper section of the pipe string to completely seal and shut down the well; After confirming that the pressure in the well is safe, when the well needs to be opened again, the cut lower section of the pipe string is lifted up; The second hydraulic oil interface (102) and the third hydraulic oil interface (103) are connected to hydraulic oil, and the remaining hydraulic oil interfaces are connected to the oil tank, and the pressure is free; The second hydraulic oil interface (102) is passed with hydraulic oil to maintain the basic safety structure (3) to prevent the cut lower section of the oil pipe from falling into the well; the third hydraulic oil interface (103) is passed with hydraulic oil, and the hydraulic oil pushes the first piston (406) to drive the emergency safety structure (2) away from the center of the blowout preventer to open the full seal; Use a tool to fix the cut lower section of the oil pipe, so that the fourth hydraulic oil interface (104) is connected to the hydraulic oil, and the remaining hydraulic oil interfaces are connected to the oil tank, and the pressure is free; The hydraulic oil pushes the second piston (407) to drive the basic safety structure (3) away from the center of the blowout preventer, thereby releasing the suspension of the oil pipe.

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