Reusable downhole swivel

Abstract

This utility model relates to reusable downhole swivels. The technical result is to expand the functionality of the downhole swivel. The downhole swivel consists of a base and an upper housing, connected to each other for rotation around a common axis by means of upper and lower bearings. The upper and lower bearings, with an intermediate nut located between them, are positioned between the base and the upper housing, supported by the middle housing, and form a bearing assembly bounded by seals within an oil-filled cavity. A compensating piston is located in the upper part of the oil-filled cavity, maintaining the operability of the bearing assembly. The intermediate nut is designed to withstand tensile and compressive loads.A movable housing is mounted on the base, allowing the swivel to be controlled by moving the locking pins along corresponding two-position shaped grooves in the rotary assembly, which is mounted between the base and the middle housing. The middle housing is designed to engage with the splines of the movable housing and disengage from them under the action of a pressure differential using a compression spring, which is covered by a cover. 1 ref. f-ly, 2 fig.

Description

[0001] The utility model relates to the oil and gas production industry and can be used in drilling and completing directional and horizontal wells, in particular when lowering into the well lower completion assemblies - liners, filters and other downhole equipment that require rotation of only the upper part of the string without transmitting rotation to the lowered liner.

[0002] A swivel sub is known for installation in a working string between a drill string and downhole equipment (according to patent US 8511392 B2, class E21B 23 / 04, published 08 / 20 / 2013), including a first cylindrical body with a sleeve portion having teeth, a second cylindrical body partially located inside the sleeve portion with the possibility of relative rotation, and a sliding sleeve with teeth interacting with the teeth of the sleeve portion and moving in the axial direction between the disengaged and engaged positions due to the pressure difference created in the sub, wherein the pressure difference is created by dropping a ball into a seat.

[0003] The disadvantage of this solution is that the pressure difference is created by dropping the ball into the seat, as a result of which the tool's flow channel narrows or completely closes, and switching from the disengaged to the engaged position is a one-time and irreversible process, which does not allow the swivel to be repeatedly locked and unlocked during the descent.

[0004] A rotary tool for use in a well is known (according to patent US 20200141202 A1, class E21B 31 / 00, E21B 17 / 07, E21B 43 / 10, E21B 17 / 05, published on 07.05.2020), comprising a tool body and a mandrel configured to be axially movable relative to the tool body, as well as a locking element movable between a first position in which the mandrel rotates relative to the tool body and a second position in which the mandrel and the tool body are rotationally connected; the locking element is configured to move between said positions in response to a mechanical axial force and a rotational force applied to the mandrel.

[0005] The disadvantage of this solution is that switching the swivel between operating positions requires mechanical manipulation of the string - applying tension while simultaneously rotating the mandrel at a specified number of revolutions, which complicates tool control and is not always feasible in directional and horizontal wells due to frictional losses along the wellbore, and also entails the risk of spontaneous swivel locking.

[0006] The closest thing to the proposed utility model (prototype) is a well swivel (according to patent RU 200883 U1, cl. E21B 17 / 046, E21B 17 / 02, published 11 / 17.2020), consisting of upper and lower cores connected to each other so as to allow rotation; a support with internal splines formed at the bottom is mounted on the upper core without the possibility of mutual rotation; the lower core is rigidly connected to the housing in the upper part; an upper bearing is mounted between the housing and the upper core, and a lower bearing is mounted between the housing and the support; a piston with external splines formed in its upper part is movably mounted on the upper core under the support, made with the possibility of axial movement inside the lower core without the possibility of mutual rotation and fixed with shear pins; when excess pressure is created under the piston, the pins are sheared, the piston moves, and its external splines engage with the internal splines of the support, providing a rigid connection of the upper and lower cores for transmitting torque.

[0007] A disadvantage of the prototype is its one-time, irreversible locking: the piston is held and released by shear pins, making it impossible to unlock and reuse the swivel after locking during a single run. Furthermore, the prototype's bearings are located within reach of the wellbore fluid (drilling mud), which contains abrasive particles, limiting their service life.

[0008] The objective of the proposed utility model is to expand the arsenal of technical means that ensure reliable and trouble-free multiple use in the process of lowering into a well.

[0009] The technical result of the declared technical solution is the expansion of the functional capabilities of the well swivel by ensuring its multiple locking and unlocking by a pressure drop without blocking the full-bore channel while maintaining its wear resistance.

[0010] The stated problem is solved, and the technical result is achieved by a well swivel consisting of a base and an upper housing, connected to each other with the possibility of rotation around a common axis by means of upper and lower bearings, in which, unlike the prototype, the upper and lower bearings with an intermediate nut placed between them are located between the base and the upper housing with support on the middle housing and form a bearing unit, limited by an oil-filled cavity by means of seals, in the upper part of the oil-filled cavity there is a compensating piston with the possibility of maintaining the operability of the bearing unit, while the intermediate nut is designed with the possibility of perceiving tensile and compressive loads;a movable housing is installed on the base with the ability to control the swivel by moving the locking pins along the corresponding two-position shaped grooves, which are made in the rotary unit, which is installed between the base and the middle housing, wherein the middle housing is designed with the ability to engage with the splines of the movable housing and disengage from them under the action of a pressure difference using a compression spring, which is closed by a lid.

[0011] In addition, the upper body has a coupling threaded connection, and the base has a nipple threaded connection.

[0012] The essence of the claimed utility model is explained by drawings, where Fig. 1 shows a longitudinal section of a well swivel in an unlocked state, and Fig. 2 - in a locked state.

[0013] The downhole swivel (Fig. 1) comprises an upper body 1 with a coupling threaded connection for connection to a drill string and a base 2 with a nipple threaded connection for connection to a downhole completion assembly. The upper body 1 and the base 2 are connected to each other so as to be rotatable around a common axis by means of an upper bearing 3 and a lower bearing 4.

[0014] An intermediate nut 5 is installed between bearings 3 and 4, supporting them and supporting both tensile and compressive axial loads. Together, bearings 3, 4, and nut 5 form a bearing assembly, which is enclosed by seals in an oil-filled cavity (not shown in the drawings), which is hermetically sealed from the wellbore environment to increase the service life of the bearing assembly. A compensating piston 6 is located in the upper part of the oil-filled cavity, automatically compensating for the pressure, volume, and temperature within the cavity, thereby maintaining the operability of the bearing assembly.

[0015] A movable housing 7 is mounted on base 2. It is designed to allow axial movement under the influence of a pressure differential and is provided with splines. The middle housing 8 is positioned such that, during axial movement of the movable housing 7, its splines engage with the middle housing 8. This locks the upper housing 1 to base 2 from free, independent rotation around its axis, ensuring torque transmission from upper housing 1 to base 2.

[0016] To control the position of the movable housing 7, the swivel is equipped with a rotary unit 9, which has two-position shaped grooves along which the corresponding locking pins 10, installed in the movable housing 7, move. The first operating position of each shaped groove corresponds to the unlocked state of the swivel (free rotation relative to the lower part), the second operating position - to the locked state (transfer of rotation to the lower part). The return of the movable housing 7 to its original position is ensured by a compression spring 11. Compression spring 11 is protected from external mechanical influences by a cover 12.

[0017] The downhole swivel works as follows.

[0018] The swivel is installed in the assembly between the drilling tool, attached to the upper body 1, and the lower assembly (shank, filters, etc.), attached to the base 2.

[0019] In the unlocked state (Fig. 1), each locking pin 10 is in the first position of the corresponding shaped groove of the rotary assembly 9, the movable housing 7 is pressed by the compression spring 11, and its splines are disengaged from the middle housing 8. The upper housing 1 and the base 2 are connected only through bearings 3 and 4 and rotate freely relative to each other. When lowering into the well, the drill string, connected to the upper housing 1, rotates to overcome the frictional forces along the borehole, while no torque is transmitted to the base 2 and the lower assembly attached to it, which eliminates damage to complex and sensitive equipment.

[0020] To lock the swivel (transfer rotation to the lower assembly) in order to bring it to the locked state, a pressure difference is created in the tool, the value of which depends on the size of the tool (Fig. 2). Under the action of the pressure difference, the movable body 7 moves in the axial direction, each locking pin 10 moves to the second position of the corresponding shaped groove of the rotary unit 9, the splines of the movable body 7 engage with the middle body 8, and the upper body 1 is locked with the base 2. In the locked state, the rotation of the drill string is transmitted through the upper body 1, the movable body 7 and the middle body 8 to the base 2 and then to the lower assembly. To unlock the swivel, a repeated pressure difference is created, as a result of which each locking pin 10 returns to the first position of the corresponding shaped groove of the rotary unit 9, and the movable body 7, under the action of the compression spring 11, returns to its original position.The splines of the movable body 7 disengage from the middle body 8, and the swivel again ensures free rotation of the upper body 1 relative to the base 2.

[0021] The number of locking pins and the corresponding two-position shaped grooves is determined by the swivel size corresponding to the size of the equipment being lowered. For example, to lower a 101.6 mm diameter shank, the proposed swivel must contain two pins and two corresponding two-position shaped grooves; to lower a 168 mm diameter shank, four pins and four corresponding two-position shaped grooves; to lower a 178 mm diameter shank, six pins and six corresponding two-position shaped grooves. The pressure differential sufficient to lock the swivel for the given shank sizes ranges from 5 to 8 atm., respectively.

[0022] The absence of a full-bore channel blockage allows for drilling fluid circulation during liner running and continued running with the ability to repeatedly lock and unlock the swivel. In turn, drilling fluid circulation allows for flushing the wellbore during liner running, thereby reducing resistance during running by clearing cuttings.

[0023] Thanks to the rotary assembly 9 with its two-position shaped grooves and the return of the sliding housing 7 by the compression spring 11, the swivel can be locked and unlocked multiple times during a single run by simply changing the pressure without blocking the flow channel. The swivel's repeated use is further enhanced by its wear resistance, as the bearing assembly is located in a sealed, oil-filled cavity under the action of the compensating piston 6, preventing the abrasive borehole environment from entering the bearing assembly and ensuring stable lubrication conditions. The intermediate nut 5 supports axial loads in both directions (tensile and compressive), increasing the bearing capacity.

[0024] Thus, the proposed utility model ensures the achievement of a technical result - expansion of the functional capabilities of a well swivel by providing its multiple locking and unlocking by a pressure drop without blocking the full-bore channel while maintaining its wear resistance.

Claims

1. A downhole swivel consisting of a base and an upper housing, connected to each other with the possibility of rotation around a common axis by means of upper and lower bearings, characterized in that the upper and lower bearings with an intermediate nut located between them are located between the base and the upper housing with support on the middle housing and form a bearing unit, limited by an oil-filled cavity by means of seals, in the upper part of the oil-filled cavity a compensating piston is located with the possibility of maintaining the operability of the bearing unit, while the intermediate nut is designed with the possibility of perceiving tensile and compressive loads;a movable housing is installed on the base with the ability to control the swivel by moving the locking pins along the corresponding two-position shaped grooves, which are made in the rotary unit, which is installed between the base and the middle housing, wherein the middle housing is designed with the ability to engage with the splines of the movable housing and disengage from them under the action of a pressure difference using a compression spring, which is closed by a lid.

2. A well swivel according to claim 1, characterized in that the upper body has a coupling threaded connection, and the base has a nipple threaded connection.

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