RU2483189C1 - Rotary ram-type well head stripper - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: stripper includes a hollow cylindrical housing with a flange, upper and lower cover plates, a rotor with upper and lower supports, which is installed so that it can be rotated in the housing. The rotor supports are installed between the cover plates, and surfaces of the cover plates and supports of the rotor, which interact between themselves, are made in the form of concentric spheres. The device also includes a sealing element of a kelly stem, which is connected to the rotor and made in the form of movable sealing rams installed in a channel made in a diametrical plane of the rotor and interacting with stocks-pistons of hydraulic cylinders made in a diametrical plane of the rotor on both sides parallel to the channel for arrangement of rams. Besides, the rams are equipped with projections of various lengths, which provide the rotor turn for coincidence of ends of rams with ends of the kelly stem. Between the rotor and upper support there located is a hydraulic distributor with supply channels of fluid from a pump to piston and stock cavities of hydraulic cylinders.

EFFECT: improving reliability, safety and convenience of operation of a rotary well head stripper.

5 dwg

Description

The invention relates to equipment for sealing the wellhead during work associated with the rotation of the lead drill pipe and drill pipe string with a mechanical driven rotor.

A wellhead sealing device is known (RF patent No. 2142552, IPC ЕВВ 33/03, published on December 10, 1999), containing:

- a hollow cylindrical body with a through channel and with a flange,

- a sealing insert interacting with the body and made in the form of a rotor with a central through channel of square shape for the passage of the lead drill pipe and stator, consisting of two equal halves and equipped with an additional sealing element and its mount on the stator;

- in this case, the rotor is equipped with a sealing element of the lead drill pipe, in which there is a through channel of square shape, the side of which is less than the square of the lead pipe.

A disadvantage of the known device is the increased complexity of operation, due to the need for disassembly and assembly of the sealant when installed on the lead drill pipe before starting work, as well as to replace worn sealing element of the lead drill pipe or additional sealing element of the stator. This operation involves the complete disassembly of the stator, installation of the rotor with the sealing element on the lead drill pipe, installation on the rotor of the stator, installation of an additional sealing element on the stator and its fastening, which together require a significant investment of time.

In addition, the rotor sealing element, when installed on the drill pipe, experiences significant deformations and is subjected to intense abrasion, which reduces the overall service life of the sealing element and requires frequent replacement. This is due to the fact that the lead drill pipe is equipped with a lower cylindrical sub, the outer diameter of which significantly exceeds the side of the square of the lead pipe and is almost equal to the diagonal of the square section of the lead pipe. In this case, the sealing element has a through channel of square shape, the cross-sectional dimensions of which in the initial state should be less than the square section of the lead drill pipe for hermetic compression. Therefore, the process of installing it on the drill pipe is difficult because it is complicated by the initial tension of the sealing element on the cylindrical part of the lower sub, which implies a significant degree of stretching of the material of the sealing element and causes significant tensile stresses in it, which can lead to irreversible plastic deformation and rupture of the sealing element . In addition, given that the lower sub constantly interacts with the gripping elements of the drill keys when screwing the lead drill pipe with drill pipes, there are always traces of this interaction on the outer cylindrical surface in the form of scratches and scoring, which, in contact with the surface of the through channel of the sealing element will leave traces of wear on its surface in the form of similar scratches and scoring, which will lead to a possible leakage of the contact area of the sealing element with the leading ryl pipe during operation and, therefore, to its inoperability. The prevention of such consequences is possible only by preliminary disconnecting the lower sub with the lead drill pipe and then screwing it again after installing the rotor with the sealing element on the lead drill pipe, however, this operation is laborious and increases the time of unproductive preparatory work.

The disadvantages of the known device should also include the need to dismantle the plug-in sealing insert from the housing during hoisting operations, with the subsequent accurate centering and cleanliness of the surface of the housing opening for a tight fit of the stator into the housing during reverse installation, which also requires additional labor.

Thus, the combination of design features and technology of using the known device for sealing the wellhead leads to an increase in the complexity of its operation, a decrease in the reliability of operation and a small service life.

Known wellhead rotary sealant (RF patent No. 2347060, IPC ЕВВ 33/03, published on 02.20.2009), containing:

- a hollow cylindrical body with flanges and a cover,

- inside of which is placed the rotor, made in the form of a coupling of the sealant and equipped with persistent and radial plain bearings,

- a sealing element of the leading drill pipe connected to the lower part of the rotor and made in the form of an annular self-sealing cuff with a through square hole,

- and the lead drill pipe coupling mounted with the possibility of longitudinal movement on the lead drill pipe and interacting with rotation with the rotor.

A disadvantage of the known device is the increased complexity of its preparation for operation, due to the need to separate the lower sub from the lead drill pipe to install the lead drill pipe coupling, which requires additional labor costs and leads to accelerated wear of the threaded connection between the lead drill pipe and the lower sub. In addition, the high complexity and complexity of the execution has the operation of replacing the self-sealing cuff when it is worn, since this requires complete disassembly of the known device. This, in turn, requires preliminary extraction of the known drill pipe from the rotor, its separation from the drill pipe string lowered into the well and sealing of both the wellhead and the upper pipe of the drill pipe string to prevent an open fountain.

The disadvantages of the known sealant should also include low reliability due to intensive wear of the surfaces of the square holes of the annular self-sealing cuff during operation and the associated probability of loss of tightness in its contact with the lead drill pipe. This is due to the fact that the diameter of the drill pipe locks passing during hoisting operations through the annular self-sealing collar is always larger than the size of the side of the square hole in it, and therefore the lock will be tightened through the square hole, subjecting the sealing element to significant tensile deformation. As a result of this, after pulling through a ring self-sealing collar several pipes with locks having scores and scratches on their outer cylindrical surface from the gripping elements of the drill key, radial wear notches will form on the sides of the square through hole of the self-sealing collar due to interactions with the locks, the presence of which does not provide reliable sealing flat faces of the lead pipe with a sealing element.

In addition, the likelihood of leaky closing of the mouth can arise as a result of the mismatch of the longitudinal axes of the descent lead pipe and the sealant housing due to inaccurate centering of the rig tower relative to the wellhead or due to the straightness of the descent pipes. Such a mismatch may occur during operation as the pipes are lowered due to the increase in the weight of the drill string, which leads to uneven settlement of the towers of the tower block and skew of the tower. The resulting radial displacement of the pipe and its one-sided impact on the sealing element causes its increased wear at the contact point and a decrease in the force of elastic compression of the lead pipe on the diametrically opposite side of the cuff, which can cause leakage of the contact and termination of flushing at the bottom of the well with the exit of fluid at the wellhead sealant body.

Leakage in the contact of the self-sealing sleeve with the lead pipe can also occur due to the mismatch of the faces of the square hole of the sleeve and the faces of the square cross-section of the lead drill pipe when the lead pipe enters the rotor of the known device. This is due to the impossibility of visual control of the position of the cuff hole and the adjustment of the rotor to match the faces, since the rotor hole after the lower lead of the lead pipe enters the cuff is closed, and also because of the lack of the known device for ensuring the coincidence of the faces of the square holes in the sleeve of the lead pipe and in a self-sealing cuff. As a result of this, irreversible deformation of the cuff, for example, in the form of tears, leading to its inoperability and the need to replace it, or gaps in the contact of the cuff with the lead pipe, may result in irreversible deformation of the cuff leading into the cuff, as a result of which when the pump is turned on, the flushing fluid will pour out well-known sealant body, not reaching the bottom of the well.

The combination of these design features reduces the reliability, safety and ease of operation of the well-known wellhead rotary sealant.

The objective of the invention is to provide a technical solution for a wellhead rotary sealant, devoid of the above disadvantages.

The technical result of solving this problem is to increase the reliability, safety and ease of operation of the wellhead rotary sealant.

To ensure this result, the known wellhead rotary sealant containing

- a hollow cylindrical body with a flange and a top cover,

- a rotor with upper and lower supports mounted rotatably in the housing,

- and a sealing element of the lead drill pipe connected to the rotor,

according to the invention

- additionally equipped with a bottom cover associated with the housing,

- installed between the rotor and the upper support valve,

- at the lower end of which there are annular grooves provided with sealing rings and interacting with mating annular protrusions made at the upper end of the rotor and forming annular gaps between the bottom of the grooves and the ends of the protrusions,

- the sealing element is made in the form of movable sealing dies installed in the channel made in the diametrical plane of the rotor and interacting with the piston rod pistons of the hydraulic cylinders made in the diametrical plane of the rotor from two sides parallel to the channel for placing the dies,

- in this case, channels are provided in the hydraulic distributor for supplying fluid from the pump to the piston and rod cavities of the hydraulic cylinders,

- and the dies are equipped with protrusions of different lengths that interact when moving with the faces of the lead pipe and provide rotation of the rotor to match the faces of the dies with the faces of the lead pipe,

- moreover, the size of the pharynx between the protrusions of the dies corresponds to the value of the diameter of the circle inscribed in the cross section of the polygon of the leading drill pipe,

- rotor bearings are installed between the covers,

- and the interacting surfaces of the covers and rotor supports are made in the form of concentric spheres.

The invention is illustrated by drawings, where figure 1 shows a longitudinal vertical section of a sealer wellhead rotary ram in the pass position of the lead pipe with sub; figure 2 - view B with the upper cover removed in figure 1; figure 3 is a section aa in figure 1; figure 4 is a longitudinal vertical section of the sealant of the wellhead rotary die, closed on the lead pipe; figure 5 - position of the dies and the protrusions of the dies at the time of the beginning of the closure on the lead pipe.

The wellhead rotary ram sealant contains (Fig. 1) a housing 1 with a flange 2 and windows 3 and 4, an upper 5 and a lower 6 cover with spherical surfaces 7 and 8, a rotor 9 placed in supports 10 and 11 with spherical surfaces 12 and 13. The bearings 10 and 11 of the rotor 9 are installed between the covers 5 and 6 and interact with bearings 14 and 15. The spherical surfaces 7, 8 and 12, 13 are concentric.

The rotor 9, rotating in bearings 10 and 11, contains a channel 16 for accommodating dies 17, hydraulic cylinders 18 with rod pistons 19, channels 20 and 21 for supplying working fluid to the piston 22 and rod 23 cavities and ring protrusions of a larger 24 and a smaller diameter 25 at the top end.

The annular protrusions 24 and 25 of the rotor 9 are placed in the annular grooves of the valve 26 with the possibility of rotation and with the formation of annular gaps of a larger 27 and a smaller diameter 28. The tightness of the interacting surfaces of the annular protrusions 24 and 25 and the annular grooves of the valve 26 is provided by the sealing rings 29 of various diameters.

The control valve 26 contains channels 30 and 31 for supplying a control hydraulic fluid to the annular gaps 27 and 28, as well as protrusions 32 for interacting with the walls of the windows 3.

The dies 17 installed in the channel 16 of the rotor 9 (Fig. 2), when moving, after the ends of their opposite protrusions 33 and 34 are in contact with each other, are sealed with flat surfaces of the faces 35 leading drill pipe 37 being lowered through the through hole 36 of the rotor 9 with the lower sub 38. This movement of the dies 17 is carried out by the piston rod 19, with which the dies 17 are connected by links 39.

The interacting surface of the piston rod 19 (Fig. 1), the rotor 9, the support 11, the housing 1 and the cover 6 are sealed with sealing rings 40 of various diameters.

The channel 16 for accommodating the dies 17 (FIG. 3) is made in the diametrical plane of the rotor 9, and the piston rod 19 of the hydraulic cylinders 18 (FIG. 2) are placed in the diametrical plane of the rotor 9 from two sides parallel to the channel 16 for placing the dies 17. The dies 17 protrusions of different lengths: long 33 and shorter in length 34, when combined, the flat surfaces of faces 35 form an opening of square section. The size of the pharynx between the protrusions 33 and 34 of the dies 17 corresponds to the diameter of the circle inscribed in the cross section of the polygon of the leading drill pipe 37.

The inventive wellhead rotary ram seal works as follows (figure 1).

The device is hermetically installed at the wellhead (the hairpin connection and the landing flange of the downstream equipment are not shown). A hydraulic pump (not shown) feeds the working fluid through the channel 31 of the valve 26, the annular gap 28, the channel 20 of the rotor 9 into the piston cavity 22 of the hydraulic cylinders 18 to move the piston rods 19 and rams 17 connected to the piston rod 19 by links 39, in order to open the dies 17 until the passage hole 36 of the rotor 9 is completely released 9. This prevents wear of the dies 17 by the equipment launched into the well. After opening the through hole 36, a well assembly (not shown in the drawing) is lowered through the lead pipe 37 until the lower sub 38 comes under the dies channel 16. Then, the hydraulic fluid is supplied through the channel 30 of the valve 26 (Fig. 4), an annular gap 27, the channel 21 of the rotor 9 into the rod cavity 23 of the hydraulic cylinders 18 to move the piston rods 19 and rams 17 connected to the piston rod 19 by links 39 until the faces 35 of the rams 17 come into contact with the faces of the drive pipe 37.

Due to the fact that the sealing element is made in the form of movable sealing dies 17, the reliability of the device increases, since there will be no wear of the flat surfaces of the faces 35 by the drill pipe couplings and the descent equipment during tripping operations, the possibility of loss of tightness in the contact of the sealing dies 17 with the lead pipe 37 is eliminated and, therefore, increases the safety of work.

If the faces of the square leading pipe 37 in the bore 36 of the rotor 9 after descent are not parallel to the flat surfaces of the faces 35 (Fig. 5), then the dies 17, moving, abut the longer protrusions 33 against the driving pipe 37 and create a torque that provides rotation the rotor 9 or the leading drill pipe 37 until the edges of the leading drill pipe 37 and the faces 35 of the dies 17 coincide, and the shorter protrusion 34 will not interfere with the rotation. After ensuring the parallelism of the faces 35 and the faces of the driving pipe 37, the dies 17 during further movement are hermetically closed and pressed by the flat surfaces of the faces 35 to the walls of the driving pipe 37 of square cross section.

Thus, after the descent of the lead drill pipe 37 of square cross section in the case of non-parallelism of its faces and faces 35 of the dies 17, the possibility of leakage in the contact of the faces of the faces 35 of the sealing dies 17 with the faces of the faces of the lead pipe 37 is excluded due to their forced coincidence and, therefore, the safety is increased device operation.

After closing the dies 17 (figure 4), work is started with the supply of drilling fluid by rotation of the lead pipe 37 and its simultaneous vertical movement towards the bottom of the well.

The rotation of the lead pipe 37 is transmitted through the surfaces of the faces 35 to the dies 17 and, further, to the rotor 9. The hydrodistributor 26 remains stationary (Fig. 1), the reactive moment is perceived by the protrusions 32 abutting against the walls of the windows 3 of the housing 1. The annular protrusions 24 and 25 of the rotor 9 rotate in the annular grooves of the directional control valve 26. The loads arising during operation from pressure forces are perceived by thrust bearings 14, 15, bearings 10, 11 and covers 5, 6.

If the axis of the borehole and the axis of the descent leading pipe 37 are not parallel, or the latter is not linear, the dies 17 interacting with the surfaces of the faces 35 with the sealing surface of the leading pipe 37 will be displaced by its bends and deviations and act on the rotor 9, deflecting it with supports 10 and 11 spherical surfaces 7 and 8 of the covers 5 and 6, self-installing interacting parts and thereby ensuring parallelism and coaxiality of the rotating rotor 9 and its nodes of the axis of the descent drive pipe 37. Due to this, cyclic, on each revolution of the pipe 37, alternating radial loads on the bearings 14 and 15 and bearings 10 and 11 are significantly reduced and the sealing surfaces of the faces 35 of the dies 17 and the surface of the sealed leading drill pipe 37 are parallelized, thereby reducing the wear rate of the dies and increasing their service life . The area of interaction in the contact of the dies 17 with the pipe 37 thus reaches a maximum value, thereby increasing the tightness and, therefore, the reliability of the inventive device.

If it is necessary to carry out tripping operations, the flow of drilling fluid is stopped and the rotation of the lead pipe 37 and the ram 17 are opened by supplying the working fluid to the piston cavity 22.

If it is necessary to replace the dies 17 during the work, the links 39 (Fig. 1) are installed by turning the rotor 9 in the perimeter of the windows 4, the sealant opens by supplying the working fluid. After removing the links 39, the dies 17 are removed from the channel 16 of the rotor 9. The new dies are installed in the reverse order.

The replacement operation of the sealing element, made in the form of dies 17, does not require disassembly of the sealant, thereby ensuring ease of operation and maintenance during operation of the inventive device.

Thus, the use of the inventive sealant provides ease of operation and maintenance during operation, improving the reliability and safety of work, as well as expanding operational capabilities compared to the analogue and prototype.

Claims (1)

A rotary diehead wellhead sealant comprising a hollow cylindrical body with a flange and an upper cover, a rotor with upper and lower supports mounted rotatably in the body, and a leading drill pipe sealing element connected to the rotor, characterized in that it is further provided with a lower cover connected with a housing installed between the rotor and the upper support of the hydraulic distributor, at the lower end of which there are annular grooves provided with sealing rings and interacting with the reciprocal ring protrusions made on the upper end of the rotor and forming annular gaps between the bottom of the grooves and the ends of the protrusions, the sealing element is made in the form of movable sealing dies installed in a channel made in the diametrical plane of the rotor and interacting with the piston rod pistons made in the diametrical plane the rotor on both sides parallel to the channel for placing the dies, while in the valve there are channels for supplying fluid from the pump to the piston and rod cavities of the guide cylinders, and the dies are equipped with protrusions of different lengths that interact when moving with the faces of the lead pipe and provide rotor rotation to match the faces of the dies with the faces of the lead pipe, and the size of the pharynx between the protrusions of the dies corresponds to the diameter of the circle inscribed in the cross section of the polygon of the lead drill pipe, the rotor support installed between the covers, and the interacting surfaces of the covers and rotor bearings are made in the form of concentric spheres.

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