RU2798532C1 - Wellhead rotary stripper - Google Patents

Abstract

FIELD: well drilling.

SUBSTANCE: invention relates to equipment for sealing a wellhead during activities related to tripping operations with a drill string and its rotation by a kelly. A wellhead rotary stripper is claimed, comprising a hollow cylindrical body with a central through channel for passing pipes with process equipment, equipped with lower and upper flanges for fastening to equipment at the wellhead and for fastening process equipment, respectively, locking covers with a central hole for centering the lowered or raised string pipes installed in a hollow cylindrical body from above and below, a rotor comprising a rotor body installed in a hollow cylindrical housing of the stripper, inside which a sealing collar and elements of its connection with the rotor body are installed. The rotor is equipped with one rotation support in the form of a rolling bearing. The stripper also comprises a working hydraulic chamber in the form of an annular cavity between the housing and the sealing element, filled with a working agent, a device for controlling the force of pressing the sealing collar to the pipe, hydraulically connected to the working hydraulic chamber, and hydraulic channels. In addition, the stripper is also equipped with a movable support installed between the rotation support and the locking cover on the side of the upper flange. The movable support is made in the form of a metal or composite washer comprising at least one sealing groove for installing a sealing ring and a structural element in the form of a shaped groove, or a shaped protrusion, or a hole, or a pin for interacting with a counter structural element in the form of a shaped protrusion, or a shaped groove, or a pin, or a hole, respectively, made in the locking cover and restricting the movable support from turning around the central axis of the rotor, but not preventing the free movement of the movable support in a plane perpendicular to the central axis of the rotor during their interaction.

EFFECT: expanded operational capabilities, increased reliability and service life, reduced operating costs and, as a result, increased the reliability of wellhead sealing during activities related to tripping operations with a drill string and its rotation by a kelly.

2 cl, 1 dwg

Description

The invention relates to equipment for sealing the wellhead during work related to the performance of tripping operations with a drill string and its rotation by a Kelly.

A wellhead sealing device is known (RU 68581 U1, IPC: E21B 33/03, publ. 11/27/2007), containing a housing with a through axial channel, having upper and lower flanges and configured to install the lower flange hermetically on the flange of the wellhead assembly, the node rotation, located in the axial channel of the body and containing coaxially installed between themselves and with the central axis of the through channel of the body, a cover with a central through hole for the passage of the kelly and a rotor mounted in the cover by means of a bearing assembly and having a central through hole for the kelly, sealing a cuff on which the rotor rests, having a central through hole in the form of a kelly and a carrier for transferring rotation to the rotor from the kelly.

The disadvantage of the known device is its limited operational capabilities, due to the fact that:

- the sealing collar can seal only a certain size of the drill pipe, for example, a section of 80×80, and with a certain shape of the ribs, which must correspond to the configuration of the hole in the sealing collar.

- the dock shelter is not designed to work with the use of power swivels, where it is necessary to seal the lead pipe of circular cross section.

Also, this device is unreliable in operation, since with constant contact of the sealing collar with the outer surface of the kelly to be sealed and the elements of the drill string (pipes, couplings, locks), intensive wear of its contacting surfaces will occur, especially during tripping operations, which may soon lead to loss of tightness at high pressure at the wellhead, to solution overflows, as well as to oil and gas intrusion.

Known wellhead sealing head (RU 2068488 C1, IPC: E21B 33/06, including: a hollow cylindrical body with a central through channel for passing pipes with technological equipment, a sealing element installed in the body on a rotation support in the form of a thrust ball bearing in the lower removable flange , a working hydraulic chamber formed by the lower annular cavity between the body and the sealing element, a chamber for adjusting the preload of the sealing element to the pipe, formed by the upper cavity of the body and a piston associated with the sealing element, hydraulic channels with a working agent connecting the working hydraulic chamber and the preload adjustment chamber with injection pump.

The disadvantages of the known device include the increased complexity of operation associated with:

- with the complexity of control during operation, caused by the need to establish a balance by selecting pressures in the return chamber and the working hydraulic chamber relative to the pressure at the wellhead using hydraulic control and distribution equipment that do not have sufficient pressure supply flexibility;

- the complexity of disassembling and assembling the device.

In addition, the known device has low reliability due to the fact that its design does not provide automatic adjustment of the pressure force of the sealing element to the pipe, depending on the pressure at the wellhead, which must be set by selecting a certain balance of pressure of the working agent in the chambers relative to the pressure at the wellhead. . Therefore, when the pressure at the wellhead changes, which can also change abruptly, a situation is possible when the pressure in the working hydraulic chamber is less than the pressure at the wellhead, as a result of which the tightness in the contact of the sealing element and the pipe will be broken and a breakthrough of well fluids will occur. In a situation where the pressure in the working hydraulic chamber will significantly exceed the pressure at the wellhead, intensive wear of the working surface of the sealing element during operation is possible, which will lead to its destruction at high pressure at the wellhead, to overflow of the solution, as well as to oil and gas intrusion. In addition, as a result of excessive friction in the zone of contact of the seal with the leading pipe during its axial movement of the column upwards, the axial load will increase, intensive wear of parts and lifting mechanisms of the lift, as well as a decrease in the load from the tool during the movement of the tool down (descent), which can lead to a decrease in drilling efficiency and the occurrence of emergency situations.

The low reliability of the operation of the known device is also due to the fact that the lower thrust bearing is not protected from the impact of a well fluid containing a solid phase, as a result of which intense abrasive wear of the bearing bodies and raceways is possible with the occurrence of a torque directed in the opposite direction with a loss of synchronous rotation with a rotating sealing element, which will lead to its destruction and loss of tightness of the device with a breakthrough of well fluids and drilling fluid, followed by a possible transition of the well into open flowing.

The known device has an increased overall height due to the presence in the design of the return chamber with an annular piston and a removable flange, which increases operating costs, as it increases the cost of installing a drilling rig, in cooperation with which the known device will be used. This is due to the fact that for ease of operation of the known device during tripping operations, it is necessary to install additional bases for the drilling rig or install additional scaffolds for maintenance personnel on the rig block around the wellhead.

Also, the known device has a complex design due to the presence of a return chamber with an annular piston, the introduction of which into the design is not functionally justified, since:

- reduction of the contact pressure between the sealing element and the pipe and, consequently, the compression force of the pipe can be achieved by reducing the pressure in the working hydraulic chamber;

- the return of the sealing element to its original state after reducing the pressure in the working hydraulic chamber can be ensured due to the elastic properties of the elastic material of the sealing element.

And, finally, the known device has a rigidly centered rotor, which leads to cyclic deformation of the elastic sealing element with the occurrence of increased alternating radial loads on the bearings due to the lack of a common center at the wellhead axis and the rotation axis of the leading pipe, which will lead to a significant reduction in service life sealing element and bearing units.

Thus, the known device has an increased complexity of operation, low reliability, increased operating costs, a complex design and a low service life of the product as a whole.

The objective of the invention is to create a device for sealing the wellhead, devoid of these disadvantages.

The technical result of solving this problem is to expand operational capabilities, increase reliability and service life, reduce operating costs and, as a result, increase the reliability of wellhead sealing during work related to tripping operations with the drill string and its rotation by the Kelly.

To ensure these results, the claimed device for sealing the wellhead, including:

- a hollow cylindrical body with a central through channel for passing pipes with process equipment, equipped with upper and lower flanges for mounting process equipment and equipment at the wellhead, respectively;

- locking covers with a central hole for centering the string of lowered or raised pipes, installed in the body from above and below;

- a rotor installed in a housing, containing a rotor housing, inside which a sealing collar and elements of its connection with the rotor are installed, equipped with at least one rotation support in the form of a rolling bearing,

- a working hydraulic chamber in the form of an annular cavity between the housing and the sealing element, filled with a working agent;

- a device for controlling the force of pressing the sealing collar to the pipe, hydraulically connected to the working hydraulic chamber;

- hydraulic channels;

ACCORDING TO THE INVENTION

- additionally contains at least one movable support installed between the rotation support and the locking cover, made in the form of a metal or composite washer containing at least one sealing groove for installing a sealing ring in order to ensure tightness between the locking cover and the cavity of the working chamber, and also at least one structural element in the form of a shaped groove, or a shaped protrusion, or a hole, or a pin for interacting with a counter structural element, made in the form of a shaped protrusion, or a shaped groove or a pin, or a hole made in the locking cover, respectively, fixing movable support from rotation around the central axis of the rotor, which does not prevent the movement of the movable support in a plane perpendicular to the central axis of the rotor;

- the sealing cuff is made of an elastic material in the form of a replaceable rotor sleeve with sealing protrusions or cavities on both ends.

- the unit for controlling and adjusting the magnitude of the force of pressing the sealing collar to the pipe contains a connected hydraulic pump or a hydraulic station with any type of drive, as well as a hydraulic accumulator included in the control unit when couplings are passed under pressure.

The invention is illustrated in the drawing.

The inventive wellhead rotary seal shown in FIG. 1, contains a hollow cylindrical body 1 with upper 2 and lower 3 flanges, has a through axial channel 4 for passing pipes 5 with couplings 6, which is closed from above and below by locking covers 7 with a central hole 8 for centering the string of lowered or raised pipes 5 with couplings 6 .

The locking covers 7 are installed in the body 1 by means of a threaded or bayonet connection and interact with the movable supports 9 containing grooves 10 in the form of guide keyways, which include pins 11 protruding from the locking covers 7 to protect the movable supports 9 from rotation around the central axis 12 .

Movable bearings 9 have an axial bore, in which radial bearings 13 and sealing rings 14 are installed, as well as an outer cylindrical neck 15, on which thrust bearings 16 are installed.

The rotor housing 17 has hydraulic channels 18 in the form of openings for the passage of the working agent 19. Inside the rotor housing 17, a sealing cuff 20 is installed, hermetically pressed by the rotor bushings 21 on both sides due to the threaded connection 22. The rotor bushings 21 are protected from unscrewing from the rotor housing 17 by locking screws 23.

The rotor housing 17 with the sealing collar 20, the rotor bushings 21, the locking screws 23 as an assembly, as well as the movable supports 9 with radial bearings 13, sealing rings 14 and bearings 16 as an assembly, are installed in the housing 1 and clamped with locking covers 7 to ensure tightness during operation. pressure with the minimum gap in the assembled package. The locking covers 7 protect against unscrewing from the housing 1 with locking screws 24.

Sealing cuff 20, sealing rings 14, 25 and 26 provide tightness between the axial channel 4 inside the body 1 by the external environment, forming a working chamber filled with a working agent 19. To remove air from the axial channel of the body 4 when it is filled with a working agent 19 through the hydraulic channel 27 use a screw 28 with a bypass channel 29 and a ball 30 interacting with the surface of the conical hole in the hydraulic channel 29 at the top of the device.

The control of the pressure inside the housing 1 is carried out by the pressure gauge 31, installed in any place convenient for reading the readings of the injection line of the working agent 19.

The inventive wellhead sealing device operates as follows.

In the position shown in the drawing, the device filled with a working agent is hermetically installed with the lower flange 3 on the upper flange of the wellhead equipment and secured with studs and nuts. The screw 28 is slightly unscrewed from the top cover 7, the sealer is connected to the high pressure line or the high pressure pump by means of a quick coupling and air is removed from the inner cavity of the sealer by supplying the working agent 19 to the sealer housing 1 until a certain amount of the working agent exits without the presence of air bubbles from the hydraulic channel 29. Next, screw 28 is tightened with the required torque into the cover 7. The necessary technological equipment is mounted to the upper flange 2, for example, a rotor for rotating the kelly. Through the central hole 8, pipes 5 with couplings 6 are lowered or lifted together with process equipment as part of the column. After the kelly is connected to the upper sleeve 6 of the lowered tubing string, various technological operations are carried out, including milling, drilling with direct or reverse flushing, including simultaneous lowering or lifting of the rotating drill string, flushing the wellbore, pressure testing of the casing string, BOP leak testing or well annulus sealing to prevent foreign objects from entering the well during work breaks.

The sealing of the wellhead in the event of an increase in pressure and overflow of the solution is carried out by supplying the working agent 19 with a high-pressure pump through the channel 27 with pressure control on the pressure gauge 31. As a result, the working agent 19 from the channel 27 enters the working cavity 4 of the housing 1 and through the hydraulic channels 18 and increases the volume of the working agent 19 in the internal channel 4 of the body 1 and elastically deforms the sealing element 20, which covers the pipe 5, the coupling 6 or the leading pipe, blocking the possibility of overflowing the solution through the inventive device due to the absence of a gap between the pipe 5, the coupling 6 or the leading pipe and the sealing element 20. Thus, the initial sealing of the wellhead is achieved, after which the supply of the working agent is stopped, the pressure in the internal cavity 4 of the housing 1 will begin to increase by the pressure of the fluid in the well. Thus, the crimping force in contact with the replaceable seal 20 with the pipe 5 will automatically, without the participation of maintenance personnel and manual control of the pressure balance, simultaneously change in proportion to the magnitude of the change in pressure in the well, which is achieved in comparison with the prototype as an increase in the reliability of the proposed device, and reducing the complexity of its operation.

During tripping operations associated with pushing and passing the couplings 6 through the sealing element 20 under pressure, a hydraulic accumulator is connected to the high pressure supply line. So, when lowering or raising a string of pipes 5 at a pressure on the wellhead, the locking joint 6, being larger in diameter than the diameter of the pipes 5, when passing through the inventive device acts on the sealing element 20, increasing its inner diameter and reducing the volume of the working hydraulic chamber 4. At the same time the working agent 19 will be forced out of the housing 1 through the channel 27 into the cavity of the hydraulic accumulator set to the required pressure. This reduces the wear of the replaceable seal 20, which increases its durability and increases the reliability of the proposed device. After the passage of the locking connection 6, the process of restoring pressure in the working hydraulic chamber 4 is automatically repeated in reverse order.

After sealing the wellhead, technological work is carried out in its wellbore with the movement of the pipe string on the leading pipe, well flushing and, if necessary, rotation of the leading pipe, which, being compressed by the sealing element 20, drags it along into rotation. And since the sealing element 20 is connected by the rotor bushings 21, and they, in turn, are installed between the movable supports 9 through the thrust bearings 16, it also starts to rotate. Due to the fact that the radial bearings 13 and thrust bearings 16 are separated from the external environment, namely the atmosphere from above and the well fluids from below by the sealing elements 20, 14, 25, 26 and are located in the cavity 4 of the housing 1, filled with a working agent, which, as a rule, machine or hydraulic oils are used, they will be constantly lubricated and cooled, without being exposed to borehole fluids and abrasive wear compared to the prototype. This eliminates the increased wear of thrust bearings 16 and the possibility of their jamming during operation, which prevents premature wear and destruction of the sealing element 20 during operation and increases the reliability of the proposed device. In addition, the service life of sealing rings 14 and radial bearings 13, operating in pressure lubrication, is significantly increased. In this case, the working agent will not mix with the well fluid, since the pressure in the cavity 4 of the housing 1 will always be higher than the pressure of the well fluid in the well by the pressure value at which the initial elastic deformation of the sealing element 20 occurs, which is required to cover the pipe 5, the coupling 6 or a square from the unloaded free state of the sealing element 20 at atmospheric pressure, which at this moment has a full bore central hole equal to the bore diameter in the covers 7 of the sealer, which prevents contamination of the working agent with the solid phase of well fluids.

With an excessively low pressure at the wellhead, a situation is possible when this pressure is not enough to reliably crimp the pipe 5 with the sealing element 20, and gaps may appear in the contact between them, through which the well fluid can flow. In this case, the working agent 19 is pumped until tight contact between the sealing element 20 and the pipe 5 is obtained and the compression force of the pipe 5 by the sealing element 20 is increased, which excludes the possibility of the well fluid overflow.

During the operation of sealers in wells with a significant, more than 2 mm, mismatch between the axis of rotation of the string 12 of the rotated pipes 5 and the axis of the wellhead flange of the well, including with the axis of the wellhead, blowout and other technological equipment mounted on it, this misalignment causes the occurrence of large radial loads both on the sealing element, and on bearing units during their operation, which significantly reduces their service life. In order to increase the service life of the components of the proposed sealer, the effect of misalignment is minimized due to the design of the sealer. The sealing element 20, the rotor housing 17, the rotor covers 21, the radial bearings 13 and the sealing rings 14 rotate in the movable supports 9. The movable supports 9 cannot rotate together with the pipe string 5 during the rotation of the pipe string 5, but can only be displaced in the radial direction in the internal cavity 4 of the body 1, that is, "float" in a horizontal plane, since they are fixed from rotation around their axis due to the interaction of their guide keyways 10 with the pins 11 installed on the contact surface of the locking covers 7. Thus, increased radial loads are excluded and increased wear of the sealing element 20, as well as radial bearings 13.

After carrying out work in the well, the pressure in the working hydraulic chamber 4 is relieved by depressurizing the high-pressure pump tank to zero, the readings are monitored by the pressure gauge 31. In this case, the sealing element 20, due to the elastic properties of the material, returns to its original position, opening the central through channel 8 of the housing 1 for passing pipes 5, couplings 6 and technological equipment.

Claims (2)

1. Wellhead rotary shelter, containing a hollow cylindrical body with a central through channel for passing pipes with process equipment, equipped with lower and upper flanges for fastening to equipment at the wellhead and for fastening process equipment, respectively, locking covers with a central hole for centering the run or lifted pipes installed in a hollow cylindrical housing from above and below, a rotor containing a rotor housing installed in a hollow cylindrical housing of the shelter, inside which a sealing collar and elements of its connection with the rotor housing are installed, while the rotor is equipped with one rotation support in the form of a rolling bearing, a working hydraulic chamber in the form of an annular cavity between the body and the sealing element, filled with a working agent, a device for controlling the force of pressing the sealing collar to the pipe, hydraulically connected to the working hydraulic chamber, and hydraulic channels, characterized in that it is equipped with a movable support installed between the rotation support and a locking cover on the side of the upper flange, made in the form of a metal or composite washer, containing at least one sealing groove for installing a sealing ring and a structural element in the form of a shaped groove, or a shaped protrusion, or a hole, or a pin for interacting with a counter structural element in the form of a shaped protrusion, or a shaped groove, or a pin, or a hole, respectively, made in the locking cover and restricting the movable support from turning around the central axis of the rotor, but not preventing the free movement of the movable support in a plane perpendicular to the central axis of the rotor during their interaction. 2. The shelter according to claim 1, characterized in that it is equipped with an additional rotation support and an additional movable support that interacts with the locking cover from the side of the lower flange.

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