RU2772031C1 - Hydraulic borehole expander - Google Patents

Abstract

FIELD: oil and gas wells construction.

SUBSTANCE: invention relates to the field of construction of oil and gas wells, namely, to devices for expanding the wellbore. The hydraulic borehole reamer contains a body with longitudinally made through grooves, in which retractable blades are pivotally mounted on the axes, reinforced on the outside with hard alloy, a spring-loaded hollow rod with a piston fixed on it, having flushing holes, an annular conical thickening, made on the outer surface of the hollow rod with the possibility blade interaction. The device contains lugs radially directed to the blades, and in each blade there are internal grooves - a longitudinal one for the corresponding lug and a shaped transverse groove for the guide pin installed in the through hole of the upper part of the lug. The base of each lug is fixed in the conical thickening of the hollow rod, and the upper part is articulated with the corresponding blade of the device by means of a guide pin on one side and internal grooves of the blade on the other side. The figured transverse groove of the blade has an arcuate shape, ensuring constant mating of the working surface of the lug with the inner surface of the groove of the blade when it is extended and returned to its original position.

EFFECT: forced return of the blades of the device from the working position to the transport is achieved.

1 cl, 7 dwg

Description

The invention relates to the field of construction of oil and gas wells, and in particular to devices for expanding the wellbore.

A retractable borehole expander is known (patent RU203929, IPC E21B 7/28, publ. 04/28/2020), including a body, inside of which there is a pusher with a piston screwed on it, compressing the spring, and a hard-alloy bushing, fixed by a lid, on which the upper centralizer. There is a stop for the piston, the blades equipped with PDC plates are fixed, while the bottom sub is screwed onto the body, equipped with a latch fixed with stoppers to prevent spontaneous lapel, and the blades are fastened with fingers in the grooves of the body and are made with a recess in the inner part, on the pusher are installed pull-out elements fixed with screws. The lower sub, the pusher and the latch are made with through central hydraulic channels of rounded shape with a diameter of 0.05-0.3 of the diameter of the expander body.

The disadvantage is the absence of radial flushing channels directed to the blades of the device, as well as the absence of a mechanism that ensures the return of the blades to their original position.

A retractable expander of an open wellbore is known (patent RU2299303, IPC E21B7/28, publ. 05/20/2007), including a sub, a pipe, sliding movable elements pivotally mounted in the longitudinal grooves of the housing with restrictive ledges, a piston on a movable hollow rod with a blocking an annular thickening on the outer surface and a jet nozzle. Moreover, the housing is equipped with a lower guide pipe, in the bottom of which there is a jet nozzle. In the cylindrical bore of the lower guide pipe there is a piston with longitudinal channels made along the perimeter, in which additional jet nozzles are placed. The stem is spring-loaded relative to the adapter. The blocking annular thickening on the rod is made in the form of a cone corresponding to the counter inner surface of the sliding movable elements.

The disadvantage is that the return movement of the blades of the device to the initial position is carried out without the interaction of the blades with the piston, i.e. the blades are engaged only on one upper side (freely suspended), and if there are caverns or local expansions in the wellbore, they can remain in an open, extended position, which is unacceptable due to the possible entry of cuttings into the device cavity with its subsequent a jam and the impossibility of extracting the expander from the well.

Closest to the claimed is an expander for simultaneous drilling and expansion on the casing string (patent RU2719880, IPC E21B 7/28, publ. 04/23/2020), consisting of a housing with through grooves, in which blades reinforced with hard alloy are placed on the axes , a spring-loaded piston with a central rod and an expanding cone at the end, which interacts with the blades, made with a protrusion and installed with the possibility of its contact with the surface of the expanding cone. The body is made integral with the coupling lower thread and is provided with flushing holes, in which nozzles are installed, aimed at the carbide cutters of the blades in the working position. The piston is made integral with the expansion cone and is installed so that under the action of the pressure drop it moves down relative to the housing. A retaining ring is installed on the outer surface of the piston, which interacts with the inner groove of the body in the working position. The blades have a cutting profile that makes it possible to evenly distribute the load on the cutters, and in the upper inner part they are equipped with shanks that interact with the upper end surface of the expander cone and hold the blades in the transport position.

The disadvantage of the prototype is the lack of a mechanism for returning the blades to their original position. The cam engagement of the blade shank and expansion cone ensures that the blades are blocked from their possible movement in the initial (transport) position, but there is no constant interaction of the device blades with the piston, which ensures their joint movement when they return to the initial position. The mechanism for returning the blades from the working position, when the blades are maximally advanced, to the initial position, when the blades are pushed into the grooves, is carried out passively, without forced action on them. If cuttings get into the cavity of the device, this can lead to the impossibility of returning the blades to their initial position and the drilling tool jamming in the column shoe.

The technical problem solved by the invention is to increase the reliability of the expander by reducing the risk of non-return (jamming) of the blades due to the ingress of sludge into the cavity of the device.

EFFECT: provision of forced return of the blades of the device from the working position to the transport one.

The problem is solved, and the technical result is achieved by a hydraulic downhole expander, containing a body with longitudinally made through grooves, in which retractable blades are pivotally mounted on axes, reinforced from the outside with hard alloy, a spring-loaded hollow rod with a piston fixed to it, having flushing holes, an annular conical thickening, made on the outer surface of the hollow rod with the possibility of interaction with the blades. In contrast to the prototype , the device contains lugs radially directed to the blades, and in each blade there are internal grooves - a longitudinal one for the corresponding lug and a figured transverse groove for the guide pin installed in the through hole of the upper part of the lug, and the base of each lug is fixed in the conical thickening of the hollow rod , and the upper part is articulated with the corresponding blade of the device by means of a guide pin on one side and the internal grooves of the blade on the other side, while the figured transverse groove of the blade has an arcuate shape to ensure constant mating of the working surface of the lug with the inner surface of the groove of the blade when it is extended and return to the starting position.

The technical result is achieved by the fact that the device contains a forced mechanism for returning the blades to the initial (transport) position, which ensures constant interaction of the hollow rod of the device with the retractable blades when the device is activated, when the blades are extended to the working position, and deactivated (bringing the blades to the initial position). This is ensured by mating the working surface of the lugs installed in the annular conical thickening of the hollow rod with the blades having internal grooves with the mating surface. And also by means of guide pins installed in the holes of the lugs, having an articulated engagement with the figured transverse groove of the blades of the device. The shape of the figured transverse groove of the blades is made from the condition of ensuring constant mating (contact) of their inner surface with the guide fingers of the lugs, which makes it possible to achieve full interaction of the blades of the device with the spring-loaded piston during their joint forward and reverse movement and to ensure the return of the blades to their initial position when the blades are retracted into the grooves of the device. Thus, a complete (continuous) interaction of the blades of the device with the piston is carried out during their joint movement, and the mechanism for returning the blades to the housing grooves is implemented.

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

Fig. 1 a), b) - the device in the transport position;

a) longitudinal section of the device in the initial (transport) position;

b) cross section of the device (section A-A).

Fig. 2 a), b) - device in working position;

a) - longitudinal section of the device in the working position (blades extended);

b) - cross section of the device (section B-B).

Fig. 3 - eye fastening unit with an annular conical thickening (fragment);

a) - node profile; b) - side view.

The figures show:

1 - device body;

2 - through groove of the body;

3 - axis of the blade;

4 - blade;

5 - carbide cutter;

6 - hollow rod;

7 - return spring;

8 - piston;

9 - flushing holes of the piston;

10 - annular conical thickening;

11 - eye;

12 - eye hole;

13 - guide pin;

14 - longitudinal groove of the blade;

15 - figured transverse groove of the blade;

16 - thrust ring;

17 - fixing screw;

18 - movable sleeve;

19 - fixing screw;

20 - fixing screw;

21 - borehole wall.

The hydraulic borehole expander comprises a body 1 (Fig. 1) with longitudinally made through grooves 2, in which blades 4, reinforced with hard alloy (cutters 5), are pivotally mounted on axes 3, a hollow rod 6, spring-loaded by a spring 7, with a piston 8 fixed to it having flushing holes 9, and an annular conical thickening 10 with lugs 11 (Fig. 2.3), having through holes 12 for guide pins 13 to interact with the blades 4. For this purpose, a longitudinal inner groove 14 is made in the body of each blade 4 (Fig. 2, 3) under the eye 11 and the shaped transverse groove 15 for the guide pin 13 of the eye 11. The movement of the return spring 7 is limited from above by the thrust ring 16, fixed relative to the body by screws 17, from below by the movable sleeve 18, fixed by the screw 19 relative to the hollow stem 6. An annular conical thickening 10 is fixed on a hollow rod with 6 fixing screws 20. The device has a locking thread at the top and bottom for connection with a drilling th column from above and with a chisel from below (in Fig. not shown).

The device works as follows.

A bottomhole rotary assembly (BHA) is assembled, containing: a bit, an inventive reamer, a drill collar, a drill string, and lowered into the well below the casing shoe into an open hole. In this case, the expander is in the transport position (blades 4 are pushed into the grooves 2 of the body), which ensures its unhindered passage in the well (Fig. 1). Upon reaching a predetermined interval for the expansion of the wellbore, the rotary drive of the drilling rig is switched on, which ensures the rotation of the drill string together with the expander. Next, the mud pump is turned on and the flushing fluid is supplied inside the drill pipes with a capacity sufficient to create excess in-pipe pressure (equal to the excess of in-pipe pressure over the annulus). Under the action of excess pressure, the piston 8, together with the hollow rod 6 and the annular conical thickening 10 fixed on it, having lugs 11 (the connection element with the hole for inserting the guide pin, which provides rotation around the pin), begins to move upward, while exerting dynamic pressure with the conical part thickenings 10 on the inner surface of the blades 4. Due to the wedging effect, the blades 4 are moved apart in the radial direction until they stop with carbide cutters 5 into the wall of the well 21 and begin to destroy it and expand the wellbore (Fig. 2). In the process of longitudinal movement of the hollow rod 6 upwards under the action of excess pressure, the movable sleeve 18, fixed on its body, transfers dynamic pressure to the return spring 7 and compresses it. The magnitude of the dynamic pressure on the spring is determined by the difference between the areas of the transverse surface of the piston 8 at the inlet and outlet of the flushing fluid and the magnitude of the excess inline pressure. Depending on the expected design dynamic pressure, a compression return spring with the appropriate specifications is selected.

Upon reaching the final depth of the expansion of the wellbore, the rotation of the drill string is stopped and the supply of drilling fluid is stopped (the drilling pump is turned off). Due to the decrease in excess pressure, the spring 7 expands and returns the hollow rod 6 together with the movable sleeve 18 fixed on it and the annular conical thickening 10 with lugs 11 to the initial position. The guide pins 13 of the lugs 11 in this case perform a return longitudinal translational movement along the figured through groove (slide along the inner surface of the figured groove) and exert dynamic pressure on the blades 4. The blades 4 of the expander due to the existing relationship with the hollow rod 6, implemented by means of the articulation of the guide pins 13 eyes 11 with figured transverse grooves 15 of the blades 4, make a return movement into the grooves of the expander body 1. This happens forcibly, under the influence of dynamic pressure from the side of the compressed return spring 7 (due to the kinetic energy of the compressed spring).

In the process of expanding the wellbore, the drilling fluid supplied by the drilling pump passes through the drill string through the central channel of hydraulic communication and flows out through the bit (not shown in Fig.), and part of it flows out through the holes 9 of the piston 8 to the hard-alloy cutters 5 of the blades 4 through the technological the gap between the body 1 of the expander and its blades 4 (not marked in Fig.). This channel of hydraulic communication opens only when the expander blades 4 are extended and touched the well wall 21, and the annular conical thickening 10, having mating surfaces with the expander body 1, disengaged from the expander body 1 and opened the passage of the flushing fluid to the expander blades (Fig. 12). The flow rate of the flushing fluid directed to the bit and the piston is determined by calculation using well-known methods from the condition of ensuring high-quality cleaning of the wellbore from drill cuttings.

Thus, the inventive expander provides a forced return of the blades of the device from the working position to the transport. The reliability of the expander operation is increased by reducing the risk of non-return (jamming) of the blades due to the ingress of sludge into the cavity of the device.

Claims (1)

Hydraulic borehole expander, comprising a body with longitudinally made through grooves, in which retractable blades are pivotally mounted on the axes, reinforced on the outside with hard alloy, a spring-loaded hollow rod with a piston fixed to it, having flushing holes, an annular conical thickening made on the outer surface of the hollow rod with the possibility of interacting with the blades, characterized in that the device contains lugs radially directed to the blades, and in each blade there are internal grooves - a longitudinal one for the corresponding lug and a figured transverse groove for the guide pin installed in the through hole of the upper part of the lug, and the base of each lug is fixed in the conical thickening of the hollow rod, and the upper part is articulated with the corresponding blade of the device by means of a guide pin on one side and the internal grooves of the blade on the other side, while the figured transverse groove of the blade has an arc brazed form with the provision of constant pairing of the working surface of the lug with the inner surface of the groove of the blade when it is extended and returned to its original position.

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