RU2225494C2 - Device for disengaging tools from operating string of piping - Google Patents

Abstract

FIELD: underground well maintenance equipment. SUBSTANCE: device has body, upper and lower switchers connected to the body. Upper switcher and body are connected by means of non-self-braking threaded couple. Inside the body below lower switcher a piston with through passage is placed. Piston is axially moveable. Piston includes a saddle for dropping ball. Piston is spring-loaded and fixed relative to the body to prevent crank. On the end of upper switcher and the upper end of piston cam half-couplings are made. During pressure forming on the piston after dropping the ball into the saddle cam half-couplings are disengaged. Then non-self-braking threaded couple is disengaged during rejection of upper switcher from the body. EFFECT: assured disengagement of device without crank and tensioning of string, possibility of repeated engagements of device parts without their removal from the well. 3 dwg

Description

The invention is intended for use in the process of underground repair of wells, mainly with the use of a continuous column of flexible pipes wound on a drum.

In field practice, devices are used for attaching a downhole tool to a string of flexible pipes (GT), which provide for the release of the GT string from a seized tool. In the simplest version, the said device consists of an upper sub attached to the GT column and a lower sub mounted on the downhole tool. The upper and lower sub are fixed between each other by a destructible element, for example, shear screws.

The disadvantages of this device are as follows:

- to release the GT column from the tool, it is necessary to apply a significant axial force that destroys the screws. However, in practice, such an opportunity is not always available, and sometimes undesirable, for example, when repairing violations in the casing by installing a sleeve (liner), adhesives, and other similar methods;

- the inability to reconnect the parts of the device without removing them to the surface to remove the destroyed screws and reassemble with new screws.

The closest prototype of the present invention can take the known device - the so-called hydraulic disconnector [1], comprising a housing, connected to it by the upper and lower sub, placed in the housing below the upper sub piston with a through channel, mounted with axial movement and made with a saddle under the reset ball. The lower sub is connected to the housing using the left-hand thread and is locked relative to it using a cotter pin interacting with the movable piston. To disconnect the device, a ball is dropped into it through the pipe string, which overlaps the seat in the piston channel. When pumping fluid under the action of a pressure differential, the piston moves down and disengages the cotter pin from the housing and the lower sub, thereby freeing the left thread between them from locking. After this, by rotating the working string of pipes to the right, the device is disconnected in the indicated left threaded connection.

The disadvantage of the described device is the need to rotate the working column to disconnect, which does not allow to use it complete with a column of flexible pipes.

Another disadvantage of the device is that after disconnection, the device cannot be reconnected until its lower part is removed from the well.

The aim of the invention is the separation of the device without rotation and tension of the column and the possibility of re-engagement of the disconnected parts of the device without removing them from the well.

In the proposed device, the goal is achieved by the fact that the upper sub and the housing are connected by means of a non-self-locking threaded pair, the piston is spring-loaded and fixed against twisting relative to the housing, and cam half-couplings are made at the end of the upper sub and at the upper end of the piston to interact with each other and to disengage when creating pressure on the piston after dropping the ball into the seat and subsequent separation of the non-self-braking threaded pair when the upper sub is diverted from the housing .

On the issue of compliance of the claimed device with the criterion of "inventive step" we report the following.

The first analogue of the device mentioned above, although it allows disconnecting the working string from the downhole tool without turning (rotating) the string, is devoid of two fundamental advantages of the proposed device, namely:

- to disconnect the analogue, an axial force is required, but not in the proposed device;

- to reconnect the analogue, it must be raised to the surface to replace the destroyed screws, and the proposed device can be reconnected and disconnected several times.

At the same time, in oilfield practice, devices of a similar purpose are also used to connect a string of pump rods to a pump plunger in cases where, for one reason or another, the pump plunger must be lowered and raised separately from the rod string. Among them, one can point to a device for connecting deep sucker rods to a pump plunger containing collet clamps [2].

The disadvantage of this device is its low reliability due to breakage of the gripper collet.

There is another device for connecting rods with underground equipment in a well that does not contain a collet grip [3].

However, this device has a complex structure with a large number of interacting parts, which reduces its reliability.

Note that the last two described devices do not have an internal channel, i.e. partially solve the problem, namely, only in terms of coupling and uncoupling of the tool with the working string, therefore it is not suitable for full use with the working string having an internal hydraulic channel.

The listed features of the proposed device, in our opinion, give it advantages in comparison with both the prototype and the well-known analogues discussed above, which allows attributing its distinguishing features to the criterion of “inventive step”.

The device in the connected position is shown in figure 1, a longitudinal section; figure 2 is a section through the cam coupling halves; figure 3 is a cross-section at the level of the details of the piston-housing.

The device is attached to the flexible pipe (GT) 1 through the upper sub 2, which is connected via a non-self-locking threaded pair 3 to the housing 4. The gap between the sub 2 and the housing 4 is sealed with a rubber ring 5. In the housing 4 there is a piston 6 with a seal 7 and a through channel 8 The piston 6 in the housing 4 is mounted on the slots 9, which allow the piston 6 to move in the axial direction without turning. The piston 6 is spring-loaded with a spring 10 and has cam halves 11 at the upper end that engage with cam halves 12 located at the end of the upper sub 2. The device is connected to the tool 14 through the lower sub 13, from which it may be necessary to disconnect the GT 1 column at or other reasons.

The operation of the device is as follows.

In the process of downhole operations, the hydraulic communication of the GT 1 cavity with the tool 14 is carried out through the channel 8 of the piston 6 and the cavity of the housing 4 and the sub 2 and 13. The tightness of the non-self-locking threaded pair 3 between the upper sub 2 and the housing 4 is achieved using the sealing ring 5. Torque (reactive moment), if it occurs when using downhole tools (for example, when drilling with a downhole motor), is transmitted from the tool 14 to the flexible pipe 1 through the slots 9 and cam the coupling halves 11 and 12. In the case when it is necessary to disconnect with the tool 14, the ball 15 is discharged into the device through the GT 1, which blocks the channel 8 in the piston 6. Subsequently, by creating pressure on the piston 6, its cam coupling 11 is disengaged from the cam coupling 12 of the upper sub 2, after which the threaded pair 3 gets the possibility of rotation and therefore is disconnected by withdrawing the upper sub 2 from the housing 4. In this case, the rotation of the upper sub 2 with self-drainage of thread 3 occurs due to torsion of GT 1 by 2-3 turnover within its elasticity. If necessary, the connection can be re-closed again, which can be done either using the same GT column, for example, after washing, re-feeding the sub 2 down, or in the case when the tool is seized by lowering the upper sub 2 on a stronger column 1, for example, on drill pipes, which make it possible to exert great tensile forces on the tool 14 for its subsequent release and rise to the surface. The process of reconnecting occurs as follows.

The upper sub 2, when the GT column is lowered down, is screwed into the housing 1 due to the non-self-braking property of the threaded pair, while the sub 2 is rotated 2-3 turns also within the elastic deformation of the column 1. During the connection, the ends of the cams of the coupling half 12 of the upper sub 2 rest against the ends of the cams of the coupling half 11 of the piston 6 and move the piston 6 downward, depressing the spring 10. At the same time, the cam coupling 12 is rotated relative to the piston 6 and its cam coupling half 11, and the piston 6 slides down about the slots 9 without turning. After combining the cams of the coupling halves to the connection position as a result of their rotation relative to each other, the spring-loaded piston 6 moves up to the height of the cams, ensuring their engagement in the tangential direction. Thus, the non-self-braking threaded pair 3 is blocked from the possibility of turning the sub 2 necessary to unscrew it, therefore, the connection becomes closed.

The authors believe that the primary field of application of the proposed device is underground well repair using aggregates with flexible tubing. Another area of possible application may be oil production by rod pumps using hollow rods, when it becomes necessary to couple hollow rods to the pump plunger under downhole conditions, when they are run separately.

Literature

1. A.S. No. 438774.

2. Abstract scientific and technical collection “Machines and oil equipment”, 1972, No. 7.

3. A.S. No. 283122.

Claims (1)

A device for uncoupling a tool from a working string of pipes, comprising a housing, upper and lower sub connected to it, a piston with a through channel located below the upper sub, installed with axial displacement and made with a saddle for a ball being dropped, characterized in that the upper sub and the housing are connected by means of a non-self-locking threaded pair, the piston is spring-loaded and fixed against rotation relative to the housing, and at the end of the upper sub and at the upper end of the piston olneny cam coupling part for cooperation with each other and disengaging when creating the pressure on the plunger after the dropping of the ball into the saddle and the subsequent separation of vapors by threaded nesamotormozyascheysya abduction top sub from the casing.

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