Device For Sealing Off A Well And A Pipe And A Fitting Method

Abstract

The invention relates in particular to a device for sealing off a well or a pipe, that comprises a tubular sleeve that can be radially expanded by an inflating fluid, in order to press hermetically against the wall of the well or pipe, which sleeve is connected to end members, at least one of which comprises an annular skirt directed towards this sleeve. It is characterized essentially in that the skirt wall has a number of through-holes therein and in that the material of the sleeve surrounds said skirt in such a way as to cover its outside and inside faces, sealing said holes and leaving no gaps.

Description

The present invention relates to a sealing device intended to ensure temporary sealing-off of a well, notably an oil well, or of a duct.

It also relates to a method for mounting such a device and more particularly its tubular sleeve on an end member.

Such a sealing device, well-known in the technical field of drilling and ducts, is usually designated by the expression “inflatable obturator” or by the term of “packer”.

It is intended to temporarily separate either one of two contiguous portions of the well or of the duct, for example in order to carrying out investigations or repairs in one of its portions.

The invention more particularly is directed to a sealing device of this kind, as an inflatable sleeve or bladder which is borne by a support intended to be introduced into the well or the duct.

Such a device generally includes:

At the deformable area:

• • a tubular and inflatable “sealing membrane” with a circular section, in a flexible and elastic fluidproof material, radially deformable outwards under the action of internal fluid pressure, in order to be hermetically applied against the “mechanical structure”;
  • a “mechanical structure”, the function of which is to withstand the forces exerted by the inflation pressure applied to the sealing membrane, this mechanical structure may be equipped with a so-called “anti-extrusion” device, the function of which is to avoid extrusion of the sealing membrane through the mechanical structure;
  • a tubular “outer skin” in an elastic and flexible material radially deformable by the movement of the mechanical structure.

At its ends:

• • a “fluidproof connection” providing the seal of the sealing membrane with the end;
  • an “axial mechanical connection” providing attachment of the mechanical structure on the end and taking the whole of the axial component forces generated by the inflation pressure
  • a “radial hold ring” providing the radial hold of the mechanical structure when it is subject to the inflation pressure.

At rest, the diameters of the device and of the seal are less than that of the well or the duct.

Once the device has been positioned in the intended area, the inflation of the obturator is generally achieved by pumping a liquid, such as water, hydrocarbon and/or sludge present inside the well or the duct.

This fluid is brought to a high pressure, capable of causing expansion of the membrane and of the mechanical structure and of firmly applying the outer skin against the wall of the relevant area in order to hermetically seal it off either temporarily or definitively.

During the inflating, the obturator both dilates radially and shortens following the geometry for making the mechanical structure.

Once the investigation and/or repair operations are completed, the obturator is deflated and the device is removed.

Of course, it may be used again later on in order to then seal off a new area of the same well or of the same duct, or be transferred to another site, in a new well or in a new duct, in order to fulfil the same function there.

Such a sealing device, placed inside a well or a duct to be sealed off, before and respectively after inflation, is illustrated in a schematic axial sectional view in the appended FIGS. 1 and 2.

The wall of a well, for example for extracting oil, or of a duct, is designated therein by reference C.

This cylindrical wall with an axis X-X′, in the case of a well, may consist in the rough wall of the drilled well, or in the wall of a lining in steel or in a synthetic material if the well is tubed.

Its axis X-X′ is positioned horizontally on the figure for the simple reason of convenience of illustration.

Its orientation may of course be different, in particular vertical or oblique.

The sealing device 1 essentially comprises a cylindrical sleeve 2 centred on the axis X-X′, and borne by a pair of retaining members 3, 4.

The latter are rigid end washers, for example in steel, connected to each other through the sleeve 2.

This sleeve has a flexible and elastically deformable wall.

The representation of this assembly is purely illustrative.

Its ends are sealed off by washers 3 and 4, which are sealably attached thereto, for example by adhesive bonding.

The dimensions of such a device may be very different depending on the applications.

Purely as an indication, the (non-inflated) sleeve for example has a length “l” equal to 2.5 m, a diameter “d” equal to 120 mm, and a wall thickness “e” equal to 20 mm.

With an apparatus of a known type, not shown, the device may be moved inside the well in order to position it facing the area to be sealed off, and to introduce a high pressure inflation liquid inside the sleeve 2.

For this purpose, the washer 3 is provided with a conduit 30 for supplying the liquid.

Such is the schematic structure of such a device.

In FIG. 2, this introduction of pressurized liquid is symbolized by the arrow P, and the internal pressure has the effect of radially deforming the wall of the sleeve outwards, so that its central portion is firmly, sealably applied against the wall C, as this is symbolized by the arrows f in FIG. 2.

As an indication, the inflation pressure may reach a value of the order of about 3.10⁷ to 4.10⁷ Pascals.

The radial expansion of the sleeve causes a reduction in its length, which brings the washers 3 and 4 closer to each other.

The diametrical deformation rate of the sleeve may attain 3:1 (diameter is tripled).

The device is therefore subject to significant mechanical stresses, this in a medium which is often aggressive and at high temperatures.

Further, such a device should be able to be used several times inside a same well or a same duct, for example around twenty times, during which it is possible to proceed with given investigations, for example measurement of the porosity of the wall, in different axially distant areas.

After each inflation-deflation cycle, the sleeve should return to a diameter close to its initial diameter, which assumes that it has good elastic properties.

Referring to FIG. 3, a portion of a retaining member 3 and of a sleeve to which it is connected is also illustrated as a schematic axial sectional view.

As this is well visible in the figure, the end member 3 ends with an annular skirt 31 which is directed towards the sleeve 2.

This skirt has reduced thickness and extends in the extension of the internal wall of the member 3. This means that there is a peripheral shoulder 32 which surrounds the skirt 31 and which is directed perpendicularly, i.e. circumferentially, with respect to the X-X′ axis of the member 3.

In the embodiment illustrated here and as shown only in the upper portion of FIG. 3, the tubular sleeve 2 has a structure analogous to the one detailed in the introduction of the present application. This means that it comprises from the inside to the outside, a sealing membrane 20, a mechanical structure 21 and an outer skin 22.

The sleeve 2 has suitable thickness and dimensions so that the sealing membrane 20 will be placed around the skirt 31, by encircling the latter, and longitudinally abutting against the aforementioned shoulder.

A radial hold ring 36, which is an integral part of the member 3, retains and confines the membrane 20 and the mechanical structure 21. The outer skin 22 will abut against this ring.

The connection between the skirt and the membrane 20 is generally made by adhesive bonding, but a difficulty consists of establishing a proper connection between the rubber of the membrane and the metal of the skirt.

This problem is even more concerning when dealing with a structure such as the one shown in FIGS. 4-6 and described hereafter.

For the sake of simplification, only the membrane 20 of the sleeve has been illustrated in these figures.

The end member 3 here also has an annular skirt 31 directed towards the sleeve. However the latter substantially extends at half thickness of the wall of the member 3, which generates two peripheral and concentric shoulders 32 and 34 positioned on either side of the skirt 31.

When the sleeve 2 is inflated, under the effect of the increasing internal pressure, the rubber begins to stretch. This phenomenon is illustrated in FIG. 5 by the arrows f.

The more the sleeve inflates, the more the rubber is subject to a significant tensile force. Of course, this force is transferred to the connection between the sleeve and the skirt 31.

Insofar that the connection between both of these components is achieved with adhesive, under the effect of a generally high room temperature (which may attain 175° C.), the adherence properties of the adhesive are diminished, and because of the traction, the rubber of the sleeve 2 is detached at the connection with the skirt.

These preferential regions in which the sleeve is detached are marked in FIG. 6 by the letter A.

Such a sealing device configuration is notably described in document U.S. Pat. No. 4,886,117.

The structure illustrated in FIG. 7 is substantially analogous to the one already described with reference to FIG. 3.

However, the presence of an annular insert 35, preferably in metal, is noted, which is both engaged into the member 3 and into the sleeve 2.

Even with this structure, one is confronted with the same problems as those which were described with reference to FIGS. 4-6.

Such an assembly is notably described in document U.S. Pat. No. 6,230,798.

The present invention aims at solving these problems by proposing a sealing device in which the connection between the sleeve and the end member is achieved in such a way that even in the case of significant force due to inflation of the sleeve, the connection between both parts is satisfactorily maintained, without any risk of detachment or breakage.

The present invention also aims at achieving this goal by retaining a globally unchanged sealing device structure.

This is therefore a sealing device used for sealing off a well or a duct, which includes a tubular sleeve which is radially expansible under the action of an inflation fluid, so that it is hermetically applied against the wall of the well or of the duct, this sleeve being attached to end members, at least one of which includes an annular skirt directed towards this sleeve.

This device is essentially characterized by the fact that the wall of the skirt is pierced with a set of opening holes and that the material of the sleeve clads this skirt so as to cover the external and internal faces of it while sealing off the holes, this without any continuity solution.

In this way, the material of the sleeve is somewhat embedded into the skirt so that these holes provide maximum surface area to the rubber in order to oppose the traction of the inflated portion of the sleeve.

Moreover, according to other advantageous and non-limiting features:

• • the sleeve from the inside to the outside consists of an inner sealing membrane, a mechanical structure and an outer skin, and it is the material of said sealing membrane which clads said skirt;
  • said holes extend circumferentially on the wall of said skirt;
  • said skirt includes at least two distinct series of holes, shifted longitudinally;
  • the holes of a first series are shifted circumferentially relatively to the holes of the neighbouring series, so that the whole assumes, as seen from above, a staggered arrangement;
  • said holes have an oblong shape;
  • the external surface of said sleeve is in the alignment of the outermost surface of said end member.

The invention also relates to a method for mounting a tubular sleeve, radially expansible under the action of an inflation fluid, onto the annular skirt of an end member of a sealing device used for sealing off a well or a duct.

This method is essentially characterized by the fact that an end member is used, the skirt of which is pierced with a set of opening holes and the material of the sleeve is overmoulded on the skirt, so as to cover the external and internal faces of it while sealing off the holes, this without any continuity solution.

According to advantageous features of this method:

• • an end member is used, the holes of which extend circumferentially on the wall of said skirt;
  • said skirt includes at least two distinct series of holes, shifted longitudinally;
  • the holes of a first series are shifted circumferentially relatively to the holes of the neighbouring series, so that the whole assumes, as seen from above, a staggered arrangement.

Other features and advantages of the present invention will become apparent upon reading the description which follows of a particular embodiment, this description will be made with reference to the appended drawings wherein:

FIG. 8 is a top view of an end member of a sealing device according to the invention;

FIG. 9 is a simplified longitudinal sectional view of a member analogous to the one of FIG. 8 to which is attached a partly illustrated sleeve;

FIG. 10 is a view analogous to FIG. 9 showing the behaviour of the sleeve of the sealing device when it is inflated.

The end member illustrated in FIG. 8 has a similar structure to the one which has already been described with reference to the prior art.

Indeed, this member has a terminal annular skirt 31 directed towards the sleeve. It extends at half-thickness of the wall of the member 3.

According to the invention, the wall of the skirt 31 is pierced with a set of opening holes referenced as 5.

As shown in this figure, these holes 5 extend circumferentially on the wall of the skirt. In other words, they are positioned along circles parallel with each other which extend perpendicularly to the X-X′ axis and to the generatrices of the skirt.

Here, one is dealing with three series S₁, S₂, and S₃ of holes, these series being longitudinally shifted relatively to each other. Of course, in other embodiments not shown, this number is different, for example larger.

Moreover, it is seen that the distribution of the holes is peculiar. Indeed, the holes of the first series S₁ are shifted circumferentially relatively to the holes of the neighbouring series S₂. The same is also true for the hole of this series S₂ relatively to the third series S₃, so that the whole assumes, as seen from above, a staggered arrangement.

The benefit of such a layout will be explained further on in the description.

With reference to FIGS. 9 and 10, a skirt 31 which only includes two series of holes 5 is illustrated.

According to the invention, the material of the sleeve 2, in this case the material of the internal membrane, clads the skirt 3 so as to cover both the external face 310 and the internal face 311 of it, while sealing off the holes 5, this without any continuity solution.

In other words, the material of the sleeve forms one body with the skirt 31 of the member 3, this material being somewhat embedded into the skirt.

The mounting of the sleeve 2 on the skirt 3 is preferably achieved by overmoulding.

The rubber which preferentially is the material of the sleeve 2, confines the skirt from the inside and from the outside.

As the holes 5 preferably have an oblong shape, they then provide the maximum surface area to the rubber in order to oppose the attraction of the sleeve during its inflating.

This tensile force is then divided between a reactive force at the holes and an adherence force at the adhesively bonded portion on the skirt.

The rubber of the sleeve therefore no longer slides on the skirt actually where the adhesive was not able to retain this movement leading to detachment.

Finally, it will be noted that the end portion of the skirt has a rounded profile in order to avoid any shearing of the rubber during the inflating phase.

Claims

1. A sealing device used for sealing off a well or a duct comprising a tubular sleeve radially expansible under the action of an inflation fluid, in order to be hermetically applied against the wall of the well or of the duct, this sleeve being attached to end members, at least one of which includes an annular skirt directed towards this sleeve wherein the wall of said skirt is pierced with a set of opening holes and said material of the sleeve clads said skirt so as to cover the external and internal faces of it while sealing off said holes without any continuity solution.

2. The device according to claim 1, wherein said sleeve from the inside to the outside, consists of an inner sealing membrane, a mechanical structure and an outer skin, wherein the material of said sealing membrane clads said skirt.

3. The device according to claim 1, wherein said holes extend circumferentially on the wall of said skirt.

4. The device according to claim 3, wherein said skirt includes at least two distinct series of holes, shifted longitudinally.

5. The device according to claim 4, wherein the holes of a first series are shifted circumferentially relatively to the holes of the neighbouring series so that the whole assumes, as seen from above, a staggered arrangement.

6. The device according to claim 1, wherein said holes have an oblong shape.

7. The device according to claim 1, wherein the external surface of said sleeve is in the alignment of the outermost surface of said end member.

8. A method for mounting a tubular sleeve, radially expansible under the action of an inflation fluid, onto the annular skirt of an end member of a sealing device used for sealing off a well or a duct comprising using an end member, the skirt of which is pierced with a set of opening holes and overmolding the material of said sleeve on said skirt, so as to cover the external and internal faces while sealing off said holes, without any continuity solution.

9. The method according to claim 8, wherein the end member is used, the holes of which extend circumferentially on the wall of said skirt.

10. The method according to claim 9, wherein said skirt includes at least two distinct series of holes, shifted longitudinally.

11. The method according to claim 10, wherein the holes of a first series are shifted circumferentially relatively to the holes of the neighbouring series so that the whole assumes, as seen from above, a staggered arrangement.