RU2788368C1 - Centralizer-stabilizer of the drill string with extendable rollers - Google Patents

Abstract

FIELD: mining industry.

SUBSTANCE: invention relates to the field of construction of oil and gas wells, namely to devices that provide centering and stabilization of the layout of the drill string in the wellbore. The downhole roller centralizer comprises a cylindrical housing with at least three longitudinal grooves equidistant from each other along its surface. In each groove on the axis parallel to the axis of the device, there is an extendable roller having a hinged connection with movable elements. The housings of the sliding rollers are made with the possibility of rotation relative to the axis. A through groove is made on each end side of the longitudinal groove. There are two hollow rods in the housing, when the rollers are extended, moving progressively towards each other. Each of the rods is spring-loaded with a return spring. On each hollow rod, cam pushers are fixed according to the number of rollers with eyelets and a piston with the possibility of translational movement of the hollow rod with a piston relative to the device housing in its through bore. One hollow rod hydraulically isolates through grooves made on one end side of the longitudinal grooves, and the other hollow rod hydraulically isolates through grooves made on the other end side of the longitudinal grooves. In each of the through grooves there is a double–arm lever mounted on the axis of rotation by means of a finger fixed in a transverse hole made in the device housing, and pivotally connected on one side to the eyelet of the cam pusher, and on the other side to the axis of the extendable roller by means of pins. The through grooves on the outside are closed with protective covers, and the extendable roller housings are rotatable relative to the axis by means of rolling bearings.

EFFECT: increase in the reliability of the device in the process of extending and returning the rollers to their original position by eliminating the impact of the external environment on the elements of the device involved in this process and reducing the number of moving links.

2 cl, 9 dwg

Description

The invention relates to the field of construction of oil and gas wells, namely, to devices for centering and stabilizing the assembly of the drill string (BHA) in the wellbore.

Known reamer bit cone (patent RU2105122, IPC E21B10/30, publ. 20.02.1998), containing a body having cones located in the corresponding grooves formed by walls longitudinal to the body. The device contains pairs of blocks, means for fixing blocks at the ends of said grooves, corresponding spindles installed between the blocks of each pair on said blocks, bearing surfaces between the spindle and blocks, walls forming a cylindrical channel axially located in each said spindle, additional walls forming a hole , located between the cylindrical channel and the outer surface of the spindle, a piston mounted for movement in the said channel between the outer end of the said channel and the said hole, and two pairs of seals, one pair at each end of the spindle, while the mentioned cone is mounted with the possibility of rotation on the outer surface of the spindle and with the possibility of transferring pressure from the outer end of the piston to the lubricant when it is in the said channel and with the possibility of driving the lubricant flow through the said hole to the said bearing surface, with one seal of each pair installed between the cutter and bearing surfaces of the spindle with supplied lubricant to prevent leakage of lubricant, and the other seal of each pair is installed between the spindle, block and cutter to prevent the penetration of abrasive material to the bearing surfaces.

The disadvantage of analogue is the low functionality due to the impossibility of changing the diameter of the device on the cutters (rollers), which are rigidly fixed in the device. This creates certain difficulties when lowering the tool into the well. So, for example, when passing through a narrowed section of the wellbore (the diameter of the wellbore is less than the nominal diameter of the bit), landings (puffs) of the drilling tool occur due to the contact of the cones with the borehole walls, which requires working through the wellbore. In expanded sections of the wellbore, where the diameter of the wellbore exceeds the nominal diameter of the bit, the cutters (rollers) do not touch the walls of the well, so the efficiency of the cutters in terms of centering the drill string and widening the wellbore is significantly reduced.

A downhole device with retractable roller bearings is known (patent RU2543010, IPC E21B 10/34, publ. 09/27/2013), intended for inclusion in the drill string and containing a housing with a longitudinal axis, at least one piston installed in the housing and moving radially relative to the longitudinal axis between a position in which the piston is retracted inward and an alternative position in which the piston is extended outward under the action of fluid pressure in the housing against the surface of at least one piston located inside the housing. At least one roller rotatably mounted on the piston or each of the pistons and capable of rolling along the wall of the wellbore when at least one piston is extended outward in its activated position to ensure stabilization of the drill string in which the specified downhole device is included , and reducing vibration and torque in it, and the device has a hole passing through at least one piston and having an axis perpendicular to the radius of the body, and at least one locking element, removable mounted in the body and protruding into the corresponding an opening, both in the retracted position of the piston and in the outwardly extended activated position of the piston, to prevent removal of the corresponding piston from the housing and counteract rotation of the piston relative to the housing.

The disadvantage of the analogue is the absence of a forced mechanism for returning the rollers to their original position - the return of the rollers is carried out passively, by turning off the supply of the drilling pumps (stopping flushing), which causes a hydraulic pressure difference between the annular and tubular space, which forms a dynamic pressure to return the pistons and rollers. However, this effort may not be enough due to the abrasive downhole environment (sand, drill cuttings), which, clogging into the gaps between the piston and the device body, creates additional friction between them, which requires more effort. In addition, the disadvantage of analog is the complexity of the design, respectively, low reliability.

The closest technical solution to the claimed is a roller centralizer used in well drilling (patent US4693328, IPC E21B10 / 34, publ. 09/15/1987), which has the ability to expand from a position with retracted rollers to a position with rollers extended to a larger diameter , to maintain concentricity in a hole with insufficient width. A diagonal cam surface (pusher) is fixed on the body above each roller. Under each roller, a diagonal cam surface is installed on the piston with the possibility of axial movement. Applying hydraulic pressure to the piston forces the rollers outward into their extended position. Once the rollers are fully extended, the lower cam surface can move further such that the axially raised surfaces above and below each roller prevent the rollers from being squeezed towards the retracted position. Links pivotally connect the holder for such a roller, the housing and the lower cam surface, respectively, to hold the rollers. Such a link has an elongated opening so that the holder can move along diagonal and axially extending surfaces instead of being limited to a circular path.

The disadvantage of the prototype is that the roller extension assembly contains a plurality of movable links pivotally connected to each other, located in an open well environment that is not protected from the effects of drilling mud and well walls containing fractions of drill cuttings with sand. Clogging into the mating surfaces of the actuating elements, they prevent the return of the rollers to their original position. As a result, the nominal diameter of the device increases and creates certain difficulties when extracting the assembly of the drill string from the well, in particular, when passing through the casing shoe, which has a smaller bore than the device.

The technical problem solved by the invention is to improve the centering and stabilization of the drill string assembly (BHA) in the wellbore by increasing the reliability of the device.

EFFECT: increased reliability of the device operation in the process of extending and returning the rollers to their original position by eliminating the influence of the external environment on the elements of the device involved in this process and reducing the number of moving links.

The problem is solved, and the technical result is achieved by a downhole roller centralizer containing a cylindrical body with at least three longitudinal grooves equally spaced from each other along its surface, in each groove on an axis parallel to the axis of the device, there is a retractable roller having a hinged connection with movable elements, and the retractable roller housings are rotatable about the axis. In contrast to the prototype , a through groove is made on each end side of the longitudinal groove, and two hollow rods are located in the body, when the rollers moving progressively towards each other are extended, each of the rods is spring-loaded with a return spring, while cam followers are fixed on each hollow rod according to the number lugged rollers and a piston with the possibility of translational movement of the hollow rod with the piston relative to the device body in its central through hole, while one hollow rod hydraulically isolates the through grooves made on one end side of the longitudinal grooves, and the other hollow rod hydraulically isolates the through grooves made on the other end side of the longitudinal grooves, and in each of the through grooves there is a two-arm lever mounted on the axis of rotation by means of a pin fixed in a transverse hole made in the device body and pivotally connected on one side to the eye of the cam follower, and on the other side - with the axis of the retractable roller by means of pins, in addition, the through grooves on the outside are closed with protective covers, and the housings of the retractable rollers are made rotatable about the axis by means of rolling bearings.

According to the invention, the outer surface of each roller is reinforced with hard alloy.

The technical result is achieved by the fact that for the extension and return of the rollers to their original position, one movable link is used for each side of the roller - a two-arm lever having a swivel with the pusher eye on the piston side and a swivel with the axis of the retractable roller on the other side, and not two movable intermediate links, as in the prototype. This greatly simplifies the design of the roller extension units and increases the reliability of the device.

In order to protect against the effects of the external environment in an open wellbore (ledges in the wellbore, drilled cuttings, sand penetrating into the mating friction surfaces of the elements, which leads to a jam), the actuating elements involved in the extension of the rollers are located in the internal cavity of the device body - in through grooves, closed from above by protective covers. In the prototype, similar actuating elements (cam followers, moving links) are made in an open design with the outer surface of the device housing and are not protected from the external environment.

The essence of the invention is illustrated by drawings, which show:

Fig. 1 – longitudinal section of the device in the transport position (the rollers are retracted into the grooves of the body);

Fig. 2 - cross section of the device in the transport position in section A-A;

Fig. 3 - cross section of the device in the transport position in the section B-B;

Fig. 4 - longitudinal section of the device in the working position (rollers are radially extended);

Fig. 5 - cross section of the device in the working position in the section В-В;

Fig. 6 - cross section of the device in the working position in the section Г-Г;

Fig. 7 - longitudinal section of the roller;

Fig. 8 - general view of the roller;

Fig. 9 - General view of the two-arm lever.

The figures show:

1 – device case;

2 - longitudinal groove of the body;

3 – roller axis;

4 – roller body;

5 - reinforced surface of the roller body;

6 - hollow rod;

7 - piston;

8 - return spring;

9 - thrust ring;

10 - fixing screw;

11 - cam follower;

12 - cam follower eye;

13 - two-arm lever;

14 - a finger of a fixed axis of a two-arm lever;

15 - through groove of the body;

16 - central through hole of the device;

17 - protective cover;

18 – hydrochamber outlet;

19 - roller thrust bearing:

20 - roller sealing unit.

The inventive device comprises a housing 1 with at least three longitudinally spaced grooves 2 equally spaced from each other, in which rollers 4 with a reinforced outer surface 5 are pivotally mounted on axes 3 (parallel to the axis of the device), rotating on thrust rolling bearings 19. Retractable roller 4 has a sealing assembly 20 (assembly 20 includes a sealing sleeve and an o-ring, not shown in the figures).

At the ends of the longitudinal grooves 2 in the body 1 of the device, through grooves 15 are made (a through groove on each end side of the longitudinal groove). Two hollow rods 6 (spring-loaded by springs 8) are installed in the housing, with the extension of the rollers moving progressively towards each other, while on each hollow rod cam followers 11 are fixed according to the number of rollers with lugs and a piston 7 with the possibility of translational movement of the hollow rod 6 with the piston 7 relative to the body 1 of the device in its central through hole, while one hollow rod 6 hydraulically isolates the through grooves 15 made on one end side of the longitudinal grooves 2, and the other hollow rod 6 hydraulically isolates the through grooves 15 made on the other end side of the longitudinal grooves 2. The through grooves are closed from the outside with protective covers 17 (each through groove has its own protective cover), fastened with screws. The casings 17 may be made of steel plate, for example.

The movement of the return spring 8 is limited by the thrust ring 9, fixed relative to the housing 1 by the screw 10. The pusher 11, by means of the eye 12 and pins (not shown in Fig.), has a hinged connection with the two-arm lever 13, which, in turn, also through the existing holes and pins ( in Fig. not shown) is articulated with the axis 3 of the roller 4 on the other side. Each two-arm lever 13 is placed in a through groove 15 and is movably fixed on the device body 1 on a fixed axis formed by inserting a pin 14 into the opening of the two-arm lever itself and into a hole corresponding to the location of the finger in the device body (made across the longitudinal axis of the body). Each roller has two levers, which are pivotally connected to the roller axis on both sides.

The device works as follows.

The proposed device is included in the drill string so that the device (one or more) is located in the inclined part of the wellbore. This is necessary to center the drill string relative to the axis of the well and create favorable operating conditions for drilling equipment. During the descent of the drill string, in a given interval of the inclined shaft, a centralizer-stabilizer (one or more) is installed, the number of which is determined by calculation using specialized programs for engineering calculations in drilling (for example, Bursoftproekt). The device does not require preliminary preparation before lowering into the well. In the transport position (Fig. 1), the retractable rollers 4 are retracted into the longitudinal grooves 2 of the body 1, while the diameter of the circle in the cross section of the device along the rollers 4 does not exceed the nominal diameter of the bit, and does not prevent the descent and free passage of the device in the well. In the working position, the rollers are extended in the radial direction until reaching the diameter of the circle corresponding to the diameter of the bit and touching the borehole wall (Fig. 4).

The principle of operation of the roller centralizer - stabilizer consists in the forced extension of the rollers in the radial direction to center the drill string relative to the axis of the well. The extension of the rollers is carried out hydraulically, by creating excess in-line pressure and maintaining it in the process of rotary or turbine drilling. In this case, the drill string lying on the lower wall of the inclined wellbore rises, which creates favorable conditions for cleaning the wellbore from cuttings and significantly reduces the friction-resistance forces of the drill string against the borehole walls. Rollers running on rolling bearings further reduce the amount of torque required to rotate the entire drill string.

After lowering the drilling tool to a predetermined depth, the mud pump is switched on and flushing fluid is supplied inside the drill pipes with a capacity sufficient to create in-line overpressure. In this case, the hydraulic pressure acts on the pistons 7 fixed on the hollow rods 6, and together with the cam followers 11 the rods move towards each other. In this case, the lug 12, which has a hinged connection with the two-arm lever 13, exerts dynamic pressure on it, which leads to the angular rotation of the two-arm lever 13 relative to its fixed axis formed by the pin 14. The two-arm lever, in turn, through the existing articulated connection with the axis 3 roller 4, exerts dynamic pressure on the roller 4, and the roller moves in the radial direction (extends) from the groove 2 of the body 1 of the device to a certain length limited by the protrusion of the body 1. In the process of longitudinal movement of the hollow rods 6, the pistons 7 transmit dynamic pressure to the return springs 8 and compress them. The magnitude of the dynamic pressure on the spring 8 is determined by the cross-sectional area of the piston 7 and the magnitude of the excess inline pressure. Calculated data show that at the value of in-pipe overpressure in the range ΔР=30…60 kgf/cm2, the pull-out force of the rollers is 945…1578 kgf, which ensures separation and lifting of the drill string from the bottom wall of the inclined wellbore. During drilling, retractable rollers 4, by touching the walls of the wells with the outer surface 5, rotate relative to their own axis 3 on rolling bearings 19, center the drill string and contribute to its “sliding” when the drilling tool is fed. The speed of rotation of the rollers exceeds the rotation frequency of the drill string by about 5 times and contributes to a better cleaning of the hole from drilled cuttings and the removal of "sludge pads".

At the end of drilling, the supply of flushing fluid is stopped (the mud pump is turned off). Due to the decrease in the amount of excess pressure, the return springs 8 open and return the hollow rods 6 together with the pistons 7 fixed to them and the cam followers 11 to their original position. This happens forcibly, under the influence of dynamic pressure from the compressed springs 8 (due to the kinetic energy of the compressed spring). Accordingly, the rollers also return to their original position.

EFFECT: increased reliability of operation when extending and returning the rollers to their original position by eliminating the impact of the external environment on the actuating elements and reducing the number of moving links. In addition, in the claimed device, the annular cavity of the hydrochamber is formed between the inner wall of the housing and the hollow rods installed inside the housing (in the prototype, the annular cavity is formed between the device housing and the annular cylinder installed and fixed on the device housing by means of a "many bolts", which complicates the design) .

The claimed device improves the efficiency of the drilling process, including due to:

- reduction of torque for rotation of the drill string with the BHA and dynamic loads (longitudinal and transverse vibrations, vibration) during the operation of the drilling tool;

- improving the cleaning of an inclined wellbore from cuttings by centering the drill string relative to the axis of the well;

- increasing the depth of drilling of the well and achieving the maximum deviation of the bottomhole by reducing the friction-resistance forces that prevent the movement of the drill string in the well;

- increasing the service life of the drill string and drilling equipment by creating favorable conditions for their operation.

Claims (2)

1. A downhole roller centralizer containing a cylindrical body with at least three longitudinal grooves equally spaced from each other along its surface, in each groove on an axis parallel to the axis of the device, there is a retractable roller having a swivel connection with movable elements, and the body retractable rollers are made with the possibility of rotation about the axis, characterized in that a through groove is made on each end side of the longitudinal groove, and two hollow rods are located in the body, when the rollers are extended, moving translationally towards each other, each of the rods is spring-loaded by a return spring, while on each hollow rod is fixed with cam followers according to the number of rollers with lugs and a piston with the possibility of translational movement of the hollow rod with the piston relative to the device body in its central through hole, while one hollow rod hydraulically isolates the through grooves made on one end side of the longitudinal grooves, and the other P a bare rod hydraulically isolates through slots made on the other end side of the longitudinal slots, and in each of the through slots there is a two-arm lever mounted on the axis of rotation by means of a pin fixed in a transverse hole made in the device body and pivotally connected on one side with an eye cam follower, and on the other hand - with the axis of the retractable roller by means of pins, in addition, the through grooves on the outside are closed with protective covers, and the housings of the retractable rollers are made rotatable about the axis by means of rolling bearings. 2. Downhole roller centralizer according to claim 1, characterized in that the outer surface of each roller is reinforced with hard alloy.

Images