RU2304694C2 - Drillable packer - Google Patents

Abstract

FIELD: oil and gas industry, particularly to plug hole annuity and to isolate productive reservoirs.

SUBSTANCE: packer comprises hollow cylindrical shaft with sealing member and extrusion washers, as well as upper and lower supports with conical surfaces installed on the shaft. Packer also has fixer, upper and lower slips made as annular sectors. Outer slip surfaces are provided with teeth. Fixer is made as body with boring adapted to receive a set of split spring washers pressed with nut. The nut is installed to cooperate with upper support. Split spring washers may contact with annular grooves made in outer surface of hollow cylindrical shaft. Annular sectors of upper and lower slips are connected with each other by means of connection rings and have annular grooves made in outer sides thereof. Longitudinal slots are made in inner slip surfaces to provide reliable serial breakage of connection rings because of decreased area of slip contact with conical surfaces of upper and lower supports.

EFFECT: increased reliability of hole annuity plugging and increased load-bearing ability of the packer.

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Description

The present invention relates to the oil and gas industry and is intended to overlap the annulus and the separation of one part of the wellbore from another.

A well-known drillable packer (see US Pat. RF No. 2128278, M. cl. ЕВВ 38/12, publ. 03/27/99, Bull. 9), consisting of a housing, an anchor assembly in the form of wedges with fixing teeth similar to notching teeth the barrel, the sealing elements, the pusher, covering the wedge, resting on the sealing element, which, in turn, through the wedge pusher interacts with bilateral wedge dies located between the sealing elements. Moreover, the wedge dies are made discontinuous, with an inner annular jumper connecting them.

Drill Packer Operation

The packer is planted using a special planting tool. Excess pressure is created in the tubing string. As a result, the sealing elements are deformed, and simultaneously through the pushers, they act on the bursting dies with the destruction of the jumper connecting them and moving to the casing wall with fixing the position of the packer in the well.

However, when using bursting dies from easily drilled materials, such as cast iron, aluminum or duralumin, the adhesion of the dies to the casing wall will not allow it to be firmly fixed in the axial channel, i.e. the pressure drop that can be sensed by the packer may be small, i.e. the device has a limited scope. The packer is designed for insulating work and well preservation, where the pressure drop of the working fluid can reach significant values that exceed the pressure at which the packer can be disrupted from the installation site.

Known drillable packer (see US Pat. RF No. 20111792, M. class. 5 EV 33/12, publ. 04/30/94 Bul No. 8), consisting of a barrel on which a sealing element with a lock of its position relative to the barrel with a plug, an inlet pipe with radial holes, a hydraulic cylinder with a piston, a sleeve, the cavity under which through radial holes communicates with a high pressure source, and an emphasis.

The latch is made in the form of spring-loaded cams placed in the radial holes of the barrel under the inlet pipe, and a sleeve with an inner conical surface, installed with the possibility of interaction with the cams.

The packer with the nodes of the used technical equipment is lowered into the well.

Carry out a hydraulic landing packer with the deformation of the sealing element in the axial direction, bringing to contact with slips with the wall of the casing.

After passing the sleeve under the cams, they occupy the initial position and fix the position of the sealing element relative to the barrel. At the end of the packer landing, the inlet pipe is disconnected from the barrel and removed with the hydraulic cylinder, bushing and stop.

The packer remains in the well to isolate the underlying unproductive or aquifers.

Disadvantage

- according to the manufacturing technology of a drillable packer, it should be made of readily destructible materials. At the same time, the slips must absorb the high axial force that exists from the action of the working medium, but it is impossible to hold the packer only due to the friction forces of the slips on the casing wall at high pressure.

The slips are cumulated into the sealing element, during the separation of which a gap is formed between the ends of each cam of the slip, there is no support from the expanding cone and there are no extrusion washers, the presence of a large gap between the slips leads to rubber leakage, which reduces the reliability of overlapping the annular gap by the sealant.

With an uncontrolled inner diameter of the casing, at the packer’s landing site and a fixed stroke size of the stem — the barrel and the associated cam retainer extending beyond the end of the sleeve after deformation of the seal, there is a possibility of the cams not coming out over the end of the sleeve due to the smaller casing’s inner diameter the columns.

When drilling a packer, it is likely that the packer can rotate with the tool - milling cutter, which leads to an increase in the time for drilling.

Known drillable packer (see AS No. 1832148, M. class. E21B 33/12, publ. 07.08.93, Bull. 29), adopted by the authors for the prototype.

The drilled packer consists of a hollow cylindrical body with a threaded thread on the outer surface, a sealing element with upper and lower antiseak plugs and supports, upper and lower slips in the form of annular sectors connected by shear elements with supports, upper and lower pushers with a clamp associated with the lower pusher a nozzle with a shank, between which a shear ring is placed. The packer is equipped with slips, the upper ends of which are rigidly connected to the upper pusher, and the lower ends are made with hooks. The upper slips are made with radial grooves, in which the lower ends of the strips are placed and there are hooks for interacting with the hooks of the strips, and radial grooves are made at the ends of the supports equipped with anti-seals.

The packer works as follows.

Using a shear ring, it is connected to the planting tool and lowered into the well on the tubing string. When applying pressure, the landing tool acts on the pusher and through the shear ring and pipe to the lower pusher. As a result, cuffs with anti-seals are deformed, and screws that connect the upper and lower slips to the upper and lower supports are cut.

Upper slips under the influence of their own weight tend to fall down, but this is prevented by strips whose hooks interact with the hooks of the slips. In the subsequent operation of the planting tool, both the upper and lower slips move uniformly and set the packer concentrically relative to the casing. At the end of the cuff deformation and the engagement of the slips with the casing wall, a shear ring is cut off, by which the packer is connected to the planting device, and the latter is removed from the well.

The packer is removed from the wellbore by drilling.

The disadvantages of the design include the fact that it is made of materials that are easily drilled. But in this case, the bearing capacity of the slips will be low, i.e. with a pressure drop perceived by the packer from below, it is likely that the latter can be removed from the installation site with the pressure of the process.

The sequence of connection of the slips to the casing wall is a prerequisite for the operation of the packer.

The technical result that can be obtained by carrying out the present invention is as follows:

- the design of the packer drilled allows you to increase the reliability of the overlapping of the axial channel of the wellbore;

- to ensure the expansion of the technological capabilities of the packer due to the perception of greater pressure both from above and from below;

- the ability to drill the packer for a small period with the ability to perceive torque by the spring retaining rings of the anchor slips;

- the exit of the retaining rings on the anchor slips beyond the teeth on their outer surface to the design height allows the retaining rings to be inserted to the design depth into the casing wall while maintaining its integrity;

- the ability to ensure a consistent landing of the lower packer slips by sealing the annular gap with the sealant and fixing its stress state by the upper slips.

The technical result is achieved using the proposed device - drilled packer containing a hollow cylindrical rod with a latch installed on it, a sealing element with extrusion washers, lower and upper supports with a conical surface, upper and lower slips made in the form of ring sectors, on the outside of which teeth are made, the clamp is equipped with a nut installed above the upper slips, and is made in the form of a package of split spring washers installed in the bore of the clamp housing for interactions with annular grooves made on the outer surface of the hollow cylindrical rod; the annular sectors of the upper and lower slips are connected to each other by connecting rings and contain on the outside the annular grooves in which split spring rings are installed, the height of which is 0.2–0.4 mm higher than the teeth of the slips.

For guaranteed and consistent destruction of the connecting rings by reducing the contact area of the slips with the conical surfaces of the upper and lower supports, longitudinal grooves are made on the inner surface of the slips.

An analysis of the inventive step showed the following: the construction of a stuffing box (packer) made of easily drilled material is known (see A.D. Amirov, S.Ovnatanov, NB Sarkisov. "Overhaul of oil and gas wells." Aznefteizdat, 1953 , p. 238-241).

The packer consists of a barrel, on the outer surface of which there are conical cast-iron bushings, a rubber sleeve, upper and lower slips connected by shear pins to the barrel. An annular notch is made on the inner side of the barrel for interaction and fixation of the deformed seal inside the axial channel of the well.

The design uses upper and lower slips, connected to each other by a ring that is destroyed when the packer is planted.

A device for mechanical installation of the packer is known, which is aimed at ensuring reliable fixation of the locking elements of the packer relative to the casing.

The packer is bundled with a device to install it.

The packer contains a barrel, upper and lower slips, stops (wedges), between which there is a seal, breakable slips covering the lower wedge.

When the tension force of the mounting barrel of the landing device increases to the breaking force of the slips, they are introduced into the casing. At the same time, the seal is deformed with the annulus overlapping.

The disadvantage is the uncontrolled deformation of the seal, since when the barrel is tensioned and the lower wedge interacts with explosive cams, it becomes necessary to determine the seal deformation force. Based on this, determine the force of the gap - the destruction of the ring connecting the cams. Nevertheless, in the case of closing the annular gap with the sealant and putting the cams in contact with the casing for fixing the packer, there is low reliability of the packer, with such a design and interaction with the casing with the teeth of the cams made of easily destructible material, there is no reliable fixation of the upper cams with lift pipe string for the same reason.

A device is known for mechanical installation of a packer (see US Pat. RF No. 219150, M. cl. ЕВВ 33/12, publ. 10/20/2002 Bull. No. 29), consisting of two main components of the device for mechanical installation of a packer, and directly the packer itself, which consists of a trunk, an abutment, an upper wedge on the trunk, breakable cams in the lower part, catching the lower wedge, and a sealant installed between the upper and lower wedges.

Packer landing - rotation of the pipe string with axial movement of the barrel of the device for a mechanical installation with upsetting. In this case, the locking cams, when interacting with the outer cone of the upper wedge, are bred in the diametrical direction with the casing being brought into interaction with the wall.

At the same time, the sealant deforms to contact with the casing pipe wall. By lowering the string of pipes and the installation shaft, the lower wedge will finally introduce breaking cams into the casing wall.

Packer design flaw

The packer is seated and the cams break when the tearing dies are pulled and moved along the cone with axial force transmitted to the sealing element.

Additional loading of the axial force of the packer barrel carries out the introduction of the teeth of the bursting dies in the casing.

It should be noted the complexity of the design and installation with the landing device of the next packer.

Thus, the achieved technical result is due to the unknown properties of the parts of the device under consideration, which allow the descent and installation of it in the well, disconnect the pipe string from it after installation, and also ensure, if necessary, its drilling with the exception of its rotation in the axial channel of the wellbore.

The invention does not explicitly follow from the prior art, i.e. meets the criterion of "inventive step".

In the patent and scientific literature, no drillable packer design was found in which at least two annular slots are made on the outer surface of the upper and lower slips to increase the reliability of adhesion to the casing, while maintaining its integrity and stability of the position of the packer in the axial channel bores with split spring rings installed in them having a triangular profile.

The constructive design of anchor slips was not found, in which split spring rings were used that protrude beyond the teeth on the surface of the slips by an amount sufficient to ensure that the latter penetrate the wall of the casing pipe to the design depth and keep the drilled packer in working position when the pressure drop is perceived as above so from below.

In addition, it is not known to use an adapter connecting the drillable packer to the pipe string, in which an external annular groove is made to form an annular bridge, which is destroyed when the pipe string is disconnected from it after landing.

The design of the drilled packer for separation of the wellbore is illustrated by drawings, where:

figure 1 presents the design of the device in section in the initial transport position;

figure 2 - design of the device when it is planted in the axial channel of the wellbore.

The inventive device consists of a hollow rod 1, at the lower end of which a support 2 is installed, which seals the axial channel 3 of the hollow rod 1.

On the hollow rod 1, lower slips 4 are connected in series, connected to each other by an annular jumper 5, on the outside of which teeth 6 and annular grooves are made 7. In the annular grooves 7, split spring rings are installed 8. A support 9 with a conical surface is inserted inside the lower slips 4 10, on which the extrusion washer 11 is mounted, the sealing element 12 with the upper extrusion washer 13. The upper support 14 is supported on the upper extrusion washer 13 with a conical surface 15 that interacts with the upper flange 16 themselves, which are connected to each other by a connecting ring 17. On the outer side of the upper slips 16, teeth 18 are made, facing upwards, and annular grooves 19 in which shear spring rings are mounted 20. On the outer side of the hollow rod 1, annular grooves 21 are made.

The upper slots 16 are pressed against the conical surface 15 of the upper support 14 by a nut 22 connected to the housing 23 of the retainer, which is made in the form of a package of split spring washers 24 installed in the bore 25 of the housing 23. The split spring washers 24 with sharp edges 26 facing the ring grooves 21 on hollow stem 1.

Inside the axial channel 3 of the hollow rod 1, a connecting thread 27 is made in the upper part, in which an adapter 28 is fixed, equipped with an annular groove 29 of the estimated depth with the formation of a tared annular jumper 30.

To ensure guaranteed and consistent destruction of the annular jumpers 5 on the lower 4 and upper 16 slips on the inner surface, longitudinal grooves of a rectangular profile and alternating longitudinal grooves of a cylindrical profile are made, which reduces the contact area of the slips 4 and 16 with the conical surfaces 10 and 15 of the lower 9 and top 14 legs.

For the descent and landing of the drilled packer into the well, a hydraulic landing tool is used that is attached to the adapter 28 and introduced into the axial channel of the casing pipes to the estimated depth. Overpressure of the working fluid creates an axial force in the housing of the hydraulic landing tool and move the housing 23 of the retainer relative to the hollow rod 1.

When this split spring washers 24 in the package interact with the mating annular grooves 21 on the outer surface of the hollow rod 1.

The axial force is communicated through the slips 16, the upper support 22, the sealing element 12, the lower support 9 with the conical surface of the lower slips 4. In this case, the ring 5 connecting the lower slips 4 is destroyed and the sharp edges of the split spring rings engage with the casing wall 8 with ensuring contact during their implementation, teeth 6 of the lower slips 4.

By further loading, the sealing element 12 is deformed to contact the casing pipe wall and the annular gap between the packer and the pipe is closed. Upon reaching the specified contact stresses between the sealing element 12 and the pipe wall, the connecting ring 17 of the upper slips 16 is destroyed and the split spring rings 20 are introduced into the interaction with the casing wall with the introduction of sharp edges to the calculated depth. This position of the upper pin 16 and the sealing element 12 is fixed by entering the split retainer spring washers 24 into the annular grooves 21 on the hollow stem 1.

The pipe string is disconnected from the drillable packer by breaking the calibrated ring jumper 30 of the adapter 28, after which part of the adapter 28 together with the pipe string is removed to the surface.

If it is necessary to remove the device from the axial channel of the wellbore, it can be removed by drilling and removing chips from the wellbore.

Claims (1)

A drillable packer comprising a hollow cylindrical rod with a sealing element mounted thereon with extrusion washers, upper and lower supports with conical surfaces, a retainer, upper and lower slips in the form of annular sectors, on the outer surface of which teeth are made, characterized in that the retainer is made in in the form of a housing with a bore, in which a package of split spring washers is located, pressed by a nut installed with the possibility of interaction with the upper support, and split spring washers with ring grooves on the outer surface of the hollow cylindrical rod, and the annular sectors of the upper and lower slips are connected to each other by connecting rings and contain on the outside the annular grooves provided with split spring rings, the height of which is 0.2-0.4 mm higher than the teeth of the slips, and to ensure guaranteed and consistent destruction of the connecting rings, by reducing the contact area of the slips with the conical surfaces of the upper and lower supports, on the inner surface of the slips are made single grooves.

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