RU2080969C1 - Machine for pipe cutting - Google Patents

Abstract

FIELD: mining industry, oil and gas industry. SUBSTANCE: invention deals with pipe cutting by lowering of machine into interpipe clearance of string of pipes to be out. Fluid from pipe conduit goes to central conduit, then goes into ring space through radial conduit, comes through conduits from body into interpipe clearance and rises through it to well-head. Pressure of fluid caused by velocity head acts on piston since summary passage of radial conduits is less than passage of pipe conduit. Under action of force caused by this velocity head piston moves downwards and presses on cutters with its end forcing them turn about axes. Cutters come out of grooves with turn. Cutters acts on pusher which moves together with stepped shank in axial hole. Moving pusher compresses spring which rests against thrust plate with other end. Cutting process starts from moment of touching of internal surface of cut casing with cutters. EFFECT: improved cutting efficiency. 2 dwg

Description

 The invention relates to drilling and can be used for cutting pipes by feeding the device into the in-pipe space of the cut pipe string.

A device for cutting pipes, containing equipped with a thrust plate and channels for the exit of the working fluid into the pipe space, a detachable hollow body, in the radial grooves of which are installed cutters and a piston located in the housing with a Central channel [1]
The known device has the following disadvantages:
1. Low reliability. Piston pumps are used in drilling, most often two-cylinder, rarely three-cylinder. Such pumps supply the working fluid with jerks. The pulsation of the working fluid pressure causes a pulsating expansion-contraction of the pipe string in the radial direction, which in turn causes a pulsating elongation-shortening of the string. With a large column length which can reach 5000 m or more, the amplitude of the column oscillations along its axis reaches significant values. Since the device for cutting pipes is suspended in the lower part of the string, the cutters after cutting into the cut-off casing pipe will necessarily be broken, since the load will be directed perpendicular to them; the installation of cutters in straight guides made in the form of radial channels in the housing does not allow the cutters to move in the direction of oscillation of the column.

 In the process of cutting, the working fluid is pumped through the pipe channel, passes through the central channel of the piston and enters the annulus through the openings available in the device body. The movement of the piston occurs due to the high-pressure head of the jet of working fluid due to the fact that the passage of the central channel of the piston is less than the passage of the pipe channel of the drill pipe string, on which the device is suspended. To judge the end of the process of cutting the production casing string can be the beginning of the movement of fluid along the annulus between the production and mechanical casing. However, some time elapses between the beginning of the movement of the fluid and the moment when this movement can be recorded, since before the fluid begins to flow through the crosspiece, the fluid level in the annulus should increase by 3-4 m by this amount, the well is usually drained when installing blowout equipment for the possibility of welding. In this time period, the cutters already do not resist the movement of the piston; the piston starts to move quickly and at the end of its stroke blocks the central channel, which causes a water hammer in the pipe channel, which will lead to a breakdown of the pump, rupture of the drill pipe string or manifold.

 2. The complexity of the operation.

 To replace worn cutters, you must completely disassemble the device; it is especially difficult to remove the cutters from the spring having a wavy shape, and then put new cutters on it, passing the spring into the holes on the tool holders.

 The basis of the invention is the task of improving the device for cutting pipes, in which due to the possibility of rotation of the cutters on the axes relative to the housing and due to the restriction of the piston stroke, the cutters are protected from loads arising from the vertical oscillation of the drill pipe string caused by uneven supply of working fluid by piston pumps , technological effectiveness of installation and dismantling of incisors in the device is ensured, prevention of water hammer in the system is ensured when the piston is committed full speed, which improves the manufacturability of the service and the reliability of the device.

 The execution of the piston is stepped, the presence of radial channels connecting the annular cavity between the outer surface of the piston and the inner surface of the housing with the central channel, the connection of the channels for the output of the working fluid with the annular cavity and the execution of the pusher stepped ensures the continuity of the flow of working fluid from the pipe channel into the annulus at any position parts of the device. This ensures that there is no water hammer in the system after the end of the cutting process.

 The installation of cutters on the axes with the possibility of rotation relative to the housing allows you to transfer lateral loads to the toolholders of the cutters, due to vertical vibrations of the column, elastic systems, spring and fluid in the pipe channel. This leads to a significant reduction in normal stresses in the tool holder and, therefore, to avoid their breakage.

 In addition, the installation of cutters on the axles significantly improves the serviceability of maintenance, since to replace worn cutters it is enough to remove the axes, replace the cutters and put the axes in place. It does not require complete disassembly of the device.

 The spring-loaded pusher of the cutters ensures the return of the device to the transport position after the end of the pipe string segment, and during the cutting process it helps to avoid random fluctuations of the cutters by continuously pressing them to the piston.

 A special hole in the thrust plate serves to guide the shank of the pusher during its reciprocating movements, which ensures the normal operation of parts of the device.

 Figure 1 shows a device for cutting pipes in a transport position; figure 2 is the same in the cutting end position.

 The pipe cutting device comprises a detachable hollow body 1, in the lower part of which a thrust plate 2 is rigidly connected with it, in which an axial hole 3 is made. In the body 1, channels 4 and radial grooves 5 are made, in which they are rotatably mounted on the axes 6 relative to the housing 1, the cutters 7. In the housing 1 is placed with the possibility of reciprocating movement of the step piston 8 with a Central channel 9 and radial channels 10 made between the Central channel 9 and the annular cavity 11 formed internally surface of the housing 1 and the outer surface of the piston 8 at stage.

 In the cylindrical bore of the housing 1 there is a pusher 12, rigidly connected with a stepped shank 13, mounted with the possibility of reciprocating movement in the hole 3. On the shank is placed with the possibility of interaction with the pusher 12 and the base plate 2 spring 14.

 The device operates as follows. Screw the device onto the drill pipe, mount the pipe string and lower it to a predetermined depth. Rotate the pipe string and at the same time feed the working fluid under pressure into the pipe channel.

 The fluid from the pipe channel enters the central channel 9, then through the radial channels 10 it enters the annular cavity 11, through the channels 4 it leaves the body into the annulus and rises to the wellhead through it. Due to the fact that the total passage of the radial channels 10 is less than the passage of the pipe channel, the fluid pressure due to the pressure head acts on the piston 8. Under the action of the force caused by this pressure, the piston 8 moves downward and presses the cutters 7 with its end, forcing them to rotate around the axes 6. When turning, the cutters 7 come out of the radial grooves 5. In this case, the cutters 7 act on the pusher 12, which moves with stepped shank 13 in the axial hole 3. The pusher 12, moving, compresses the spring 14, which at the other end abuts against the thrust plate 2.

 From the moment the cutters 7 touch the inner surface of the cut casing, the cutting process begins. The movement of the piston 8 is slowed down and is now determined by the speed of introduction of the cutters 7 into the cut pipe. The working fluid emerging from the channels 4, washes the cutters 7 and helps to remove chips from the cutting zone.

 Vertical vibrations of the drill pipe string are monitored by cutters 7, which, due to vertical movements of the housing 1, make reciprocating movements around the axles 6, periodically lifting the piston 8. The spring-loaded plunger 12 contributes to the continuity of contact between the cutters 7 and the piston 8.

 As they are introduced into the pipe to be cut, the cutters 7 are rotated relative to the housing 1 to an ever greater angle, gradually compressing the spring 14 through the pusher 12.

 After cutting, when, thanks to the separation of the production casing into two parts, the annulus is connected with the space between the production casing and the technical casing, the working fluid flows through the latter to the wellhead and, after raising the level by 3-4 m, it is poured out through the outlet of the crosspiece, signaling the end of the process cutting.

 If the pumps supplying the working fluid are not stopped in time, the stepped shank 13, having made a full stroke, abuts against the end face of the thrust plate 2, thereby restricting the movement of the piston 8 through the pusher 12 and cutters 7. In this position of the device, the annular cavity 11 retains some final the volume and flow of the working fluid from the pipe channel through the axial channel 9, radial channels 10, annular cavity 11 and channels 4 will continue, which eliminates the phenomenon of water hammer.

 After stopping the pumps supplying the working fluid, the pressure above and below the piston 8 is balanced and the force acting on the piston 8 from above disappears. Previously compressed spring 14 pushes the pusher 12 with the stepped shank 13 up, the cutters 7 rotate on the axes 6, enter the grooves 5 of the housing 1, and the piston 8 rises to the upper position until it stops in the housing 1; the device takes the transport position, after which it is lifted and removed from the drill pipe.

 To replace the worn cutters 7, the axles 6 are removed from the housing 1, the worn cutters 7 are replaced with new ones, and then the axles 6 are replaced.

Claims (1)

 A device for cutting pipes, comprising a detachable hollow body equipped with a thrust plate and channels for the outlet of the working fluid into the pipe space, in which radial grooves are mounted cutters, and a piston with a central channel located in the housing, characterized in that the piston is stepped with formation between the outer surface the piston and the inner surface of the cone of the annular cavity, in the piston of the device are made communicating with the central channel of the piston and with the annular cavity radial channels, channels for output p barrels of liquid into the tube space are connected with the annular cavity, an axial hole is made in the thrust plate of the device body, the cutters are mounted in radial grooves of the body on the axes with the possibility of rotation relative to the body, the device is equipped with a spring-loaded pusher of the cutters, the pusher of the cutters is equipped with a stepped shank mounted with the possibility of return translational movement in the axial hole of the thrust plate.

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