WO1999025951A1

WO1999025951A1 - Device for fixing a filtering cover inside a well

Info

Publication number: WO1999025951A1
Application number: PCT/FR1998/002352
Authority: WO
Inventors: Pierre-Yves Corre; James Leitghton; Jean-Louis Saltel
Original assignee: Drillflex
Priority date: 1997-11-17
Filing date: 1998-11-04
Publication date: 1999-05-27
Also published as: FR2771133A1; FR2771133B1; AU1159199A

Abstract

The invention concerns a device characterised in that it comprises: a flexible and inflatable tubular sleeve (2), radially expansible by the effect on an internal pressure (P) generated by a fluid; a series of ring-shaped elements (3) likewise radially expansible and enclosing said sleeve (2) by being spaced from one another, said elements (3) being made of an initially flexible material, but capable of being hardened by polymerisation; a tubular filtering cover (4), enclosing the series of ring-shaped elements (3), and also radially expansible; means for polymerising said ring-shaped elements (3) when the sleeve is inflated; said sleeve being detachable from the filtering cover (4) and from the polymerised ring-shaped elements (3), after it has been deflated. The invention is useful for fixing a filter in a well, in particular an oil well, to prevent the inflow of sand particles into the well.

Description

DEVICE FOR PLACING A FILTERING ENVELOPE

INSIDE A WELL

The present invention relates to a device for installing a filtering envelope inside a well, in particular an oil well, and more specifically inside the casing for consolidating the well.

In an oil production well, in the region of the subsoil which contains the hydrocarbons - commonly called "reservoir" - the lining which constitutes the actual wall of the well has perforations through which the hydrocarbons can penetrate inside. of Wells.

They are then transported to the surface (well head) through a tube coaxial with the liner, and of smaller diameter. The centering and sealing of this tube - which will be called hereinafter "production tubing" - in the liner are carried out by means of a shutter, commonly designated by the English term "packer".

It is quite common for particles of sand to be entrained by liquid hydrocarbons, from the reservoir to the interior of the well, through the perforations in the liner.

This is particularly the case when dealing with unconsolidated sandstone reservoirs, reservoirs with low cementation or shallow depths.

This can also happen with wells with a high flow rate, or in the event of the arrival of water due to the depletion of the reservoir, and for other reasons. The transfer of sand into the well poses significant technical problems, since it presents a risk of obstruction of the well and failure of the downhole equipment, which obviously leads to a reduction in productivity.

In addition, the sand particles cause erosion of the various materials used, which increases the maintenance costs of the well. To solve this problem, it is known to use metal strainers installed, either before the well is put into production, or after the start of production, when the aging well begins to produce sand.

By construction, the outside diameter of these strainers is close to the inside diameter of the wall to be treated. When the strainers are installed before the well is put into production, they are provided for in the architecture of the well; their installation therefore generally poses no problem, since it is carried out before the installation of the "production tubing". The present invention is not intended to replace these known techniques.

When the strainers have to be positioned after production, the problem is more complex. Indeed, on the one hand the wells were often not designed to receive this type of equipment and on the other hand the "production tubing", because of its small diameter, prevents, without its removal, the installation of the strainer.

In addition, the wells are generally not rectilinear, which makes it difficult to lower long and fragile metal strainers.

Obviously, the internal and external dimensions of these metal strainers prohibits any placement of a strainer through a strainer already installed, which greatly limits their use.

The present invention aims to overcome these difficulties by proposing a device for installing a filtering envelope inside the liner, the device thus being designed so that the installation can be done through the production tubing and, if necessary , through filters already in place.

This objective is achieved, in accordance with the invention, thanks to the fact that the device comprises:

- a flexible and inflatable tubular sleeve, radially expandable under the effect of an internal pressure generated by a fluid; - A series of annular elements also radially expandable and which surround said sleeve being axially spaced from each other, these elements being made of a material initially flexible, but hardenable by polymerization;

- a tubular filter envelope - possibly made up of several independent sections - surrounding the series of annular elements, and also radially expandable;

- Means for polymerizing said annular elements when the sleeve is inflated; said sleeve being detachable from the filtering envelope and from the polymerized annular elements, after deflation. Furthermore, according to a certain number of additional non-limiting characteristics of the invention:

- Said elements can be polymerized hot by the Joule effect, by means of heating resistors embedded in the sleeve;

- Said annular elements are housed in grooves formed in the external wall of the sleeve, the assembly having a cylindrical shape;

- The mutual spacing of the annular elements is substantially greater than their axial dimension; - the filter envelope is formed of braided wires which allow its axial retraction during its radial expansion;

- the filter envelope consists of one or more flexible and permeable sheet (s) wound on it (s) - itself (s) to form an unclosed tube; - The filtering envelope consists of several flexible and permeable sheets which are curved and fixed to the periphery of the annular elements so as to partially overlap, in the manner of tiles.

- The filter envelope is subdivided into several independent sections placed end to end, and whose end zones overlap said annular elements. Other characteristics and advantages of the invention will appear from the description and the appended drawings which represent, by way of non-limiting examples, possible embodiments. In the figures:

- Figure 1 is a schematic view, in axial section, of an oil well which it is desired to fill with a filter envelope;

- Figure 2 shows, still in axial section, a device according to the invention;

- Figures 3 and 4 show, very schematically, the filter envelope which is provided with the device of Figure 1, respectively before and after its radial expansion;

- Figures 5 to 10 are diagrams showing the different steps of setting up the filter envelope in the well using this device;

- Figures 11 and 12 show very schematically, and in perspective, a first variant of the envelope, respectively in the radially unexpanded and expanded state;

- Figure 13 is a view similar to that of Figure 11, which shows a second variant of the filter envelope.

- Figure 14 is a view in axial half-section, which shows a possible embodiment of the envelope, composed of several independent sections. In FIG. 1, the well lining has been designated by the reference C, by the reference T the production tubing, by the reference OH the obturator (or "packer") which ensures its centering in the well, by TP the head wells where the surface equipment is located, and by R the reservoir, ie the subsoil area in which the hydrocarbons to be extracted are found. At the level of the tank, the lining C is pierced with a multitude of perforations A through which the hydrocarbons enter the well, as symbolized by the arrows i. When there is a problem with the arrival of sand, it is desirable to fill a portion of the liner located in this area with a filter, so as to prevent the passage of sand particles through the perforations A.

Of course, the porosity of the filter must be adapted to the grain size of the sand.

The casing C and the production tubing P are, for example, cylindrical steel tubes.

The diameter D of the liner is significantly larger than the diameter D ₀ of the production tubing. As an indication, Do is for example between 50 and 110 mm, while D is between 54 and 160 mm.

The objective of the invention is to garnish with a filtering element the portion of the lining situated at the level of the reservoir R without having to remove the production tubing T.

The device shown in Figure 2 allows this operation to be carried out. This device, referenced 1, has a generally cylindrical shape, with a free end 12 in the shape of a warhead. It is this end which is intended to be directed towards the bottom of the well when the device is used.

The device is fixed to the end of a control rod 10, by means of a connection member 11. The rod 10 is tubular, and is suitable for bringing a liquid under pressure, for example water and / or hydrocarbons pumped into the well, inside the device, and more specifically inside the hollow sleeve 2 which will be described later.

In one possible embodiment, the rod 10, which goes up to the wellhead, has the function of guiding the device during its descent or its ascent, of bringing a liquid under pressure from the surface to the device interior, and has electrical power cables. These are symbolized by a dotted line referenced 100. Their function will be explained below.

According to a variant, the rod 10 can be connected to a suitable tool making it possible to pump the liquid from the well towards the interior of the device, said tool being itself connected to the well head by electrical supply cables.

In its natural form, which is that illustrated in FIG. 2, the diameter d of the device 1 is slightly less than the diameter D ₀ of the production tubing.

This device comprises a tubular sleeve 2, generally cylindrical, made of flexible and elastic material, for example synthetic rubber (elastomer). This sleeve has a central bore 21 which is closed at the end 12 (bottom end), into which the tubular rod 10 opens at the opposite end (in the upper part), via the connector 11.

As an indication, the wall thickness of the sleeve 2 is between 5 and 20 mm.

By introducing a pressurized fluid into the channel 21, it causes a radial expansion of the sleeve.

The characteristics of the material constituting the sleeve and its wall thickness are chosen so that the sleeve has the capacity, in the inflated state, to reach at least the diameter D of the liner.

In the outer wall of this sleeve 2 is hollowed out a series of annular recesses - or grooves - 22 regularly distributed over the entire length of the sleeve.

In the illustrated embodiment, these recesses have a rectangular section, the depth of which corresponds approximately to half the thickness of the sleeve.

The axial dimension a of the recesses 22 is substantially smaller, for example half, by the value of their mutual spacing b.

As an indication, a is of the order of 10 to 50 mm, while b is of the order of 20 to 100 mm.

The total length L of the sleeve is chosen, of course, as a function of the length of the lining section to be treated.

As an indication, it is between 2 and 20 meters.

The annular recesses 22 are lined with a material 3 which is initially flexible, and also, radially expandable, but which is thermally and / or chemically curable.

It is preferably a polymerizable resin under the effect of heat.

Inside the wall of the sleeve 2 are embedded one or more windings of heating wires referenced 20. These are suitably supplied with electrical energy via the cables 100 mentioned above.

It is thus possible to carry out the polymerization of the annular elements 3 by the Joule effect, the heat emitted by the heating wires being transmitted to the latter.

The wires 20 are wound within the wall of the sleeve and in a configuration which does not hinder the radial expansion of the device; this is the case of a helical winding, the radial expansion of which results in the reduction of the pitch. The external diameter of the annular elements 3 is identical to that of the non-recessed portions of the sleeve 2, so that the assembly forms a cylindrical part.

A filter envelope 4 is fitted onto this assembly. It is a thin cylinder, with a thin and flexible permeable wall, also capable of expanding radially in order to accompany the joint expansion of the sleeve 2 and of the elements. ring finger 3.

The porosity of the filter envelope 4 is naturally adapted to the particle size of the sand particles which it is desired to stop. As an indication, its mesh width is of the order of a few tenths of a millimeter.

The cylindrical envelope 4 consists for example of braided or woven threads or fibers.

In the embodiment illustrated very diagrammatically in FIG. 3, it is a braiding which comprises two series of threads or fibers intertwined 40,41.

Each series of threads or fibers is wound in a helix, and the two series have an opposite orientation, forming an angle α between them.

As an indication, the value of the angle α is approximately 30 to 50 °.

This kind of tubular structure of braided and interlaced wires or fibers has the property of being able to deform, by modifying the angle of the two series 40 and 41, its radial expansion resulting in an increase in the angle α and a shortening of its initial length.

This phenomenon is easily understood when comparing Figures 3 and 4; in this last figure, we have designated by d 'and 1' respectively the diameter (which has increased) and the length (which has decreased) under the effect of the internal pressure P which has caused the expansion of the envelope 4 .

As an indication, if we consider the values given above for α, the new angle α 'between the two series of wires or fibers 40 and 41 is of the order of 80 to 110 ° for example. The wires or fibers which constitute the braiding of the envelope 4 are of any material, having sufficient mechanical and anti-corrosion resistance to suit the required operating condition.

Mention may be made, as suitable materials, of metallic wires, carbon fibers, glass fibers, or Kevlar fibers. With reference to FIGS. 5 to 10, we will now explain how the filtering envelope is placed inside the well using the device which has just been described above. The envelope 4 can be simply fitted onto the elements 2 and 3, with little play, the friction of the envelope with its elements being sufficient to ensure their joining.

It is also possible to provide a fixing, for example by gluing, of the envelope 4 on the annular elements 3.

The device 1 is lowered into the well through the production tubing T of larger diameter, as illustrated in FIG. 5, the movement of descent of the device into the well being symbolized there by the arrow F.

The device is thus brought into the area to be treated, position illustrated in FIG. 6.

A pressurized fluid is then introduced inside the device, as illustrated by the arrows P in FIG. 7, which has the effect of inflating it.

Preferably, the inflation takes place gradually from one end to the other of the device, and more precisely from the end 12 in the direction of the other end, that is to say from the bottom to the top.

A special arrangement can be provided in the sleeve 2 so that the inflation takes place gradually from the bottom to the top.

An arrangement of this type is the subject of patent application FR-A-2 737 533, in the name of the applicant; according to this document, to which reference may be made if necessary, a series of frangible compression rings lining the sleeve ensures progressive inflation in the axial direction.

Thus, the sleeve 2, as well as the annular elements 3 which it carries, will, by expanding, force the envelope 4 to be applied intimately against the internal face of the wall of the lining C, including opposite the holes A. Figure 8 shows the assembly at the end of inflation; as already said, due to the radial expansion of the device, it also results in axial compression, that is to say a decrease in length. Other devices can allow radial expansion without reduction in length.

As a result of the braided structure of the filter envelope, the latter "accompanies" the device in its shortening.

While the device is maintained under the internal pressure P, the annular elements 3 are polymerized. This hardening treatment is carried out thermally, by the Joule effect, by supplying electric current to the heating wires.

Once the heat treatment has been completed, the sleeve 2 is deflated by placing it under internal vacuum symbolized by the arrow Q in FIG. 9. The sleeve therefore retracts radially, and it separates from the annular elements 3 which have become rigid. These remain in place, as well as the filter envelope 4, which remains adhere to the internal face of the cylindrical wall of the casing C.

The sleeve thus stripped can thus be withdrawn by pulling towards the surface, which is symbolized by the arrow Z in FIG. 9.

There therefore remains inside the concerned area of the lining C a filter formed by an envelope 4 held in place by the rings 3 (cf. FIG. 10).

During the subsequent exploitation of the well, the hydrocarbons can pass through the filter in the zones of the envelope which are not opposite the elements 3. On the contrary, the sand particles are stopped, and remain at the 'outside.

As the impermeable zones (corresponding to the annular elements 3) have a substantially smaller surface than the permeable zones (exposed areas of the envelope 4), the overall extraction process, and in particular the flow rate, is not affected in practical by the presence of this filter.

In the variant illustrated in Figures 11 and 12, the filter envelope is not expandable by elasticity in the radial direction; however it can deploy.

This envelope, designated 4 ′, is formed from a semi-rigid sheet in the form of a grid which is rolled up to form an unclosed cylinder. The two longitudinal edges of this cylinder largely overlap in the initial state, which allows

the "opening" of the cylinder under the effect of an internal pressure as illustrated in figure 12.

In the variant of FIG. 13, the filter 4 "is made up of several portions of semi-rigid sheets 40 ′, which have the shape of cylindrical arcs partially overlapping in the manner of tiles. One of the edges of each sheets 40 ", corresponding to a generator, is fixed to the elements 3 (only one of which is visible in the figure).

The opposite banks are free.

It is understood that thanks to this arrangement, under the effect of internal pressure the overlap of the different sheets 40 "will decrease, the expansion of the assembly remaining possible.

The sheets 40 "are for example perforated by a multitude of small holes which constitute the openings of the filter.

It goes without saying that the sheets 40 "could be constituted by grids similar to the sheet 4 'of FIGS. 11 and 12, and vice versa. The polymerization of the annular elements 3 is not necessarily carried out by Joule effect. It could be obtained using, for the inflation of the sleeve, a hot liquid capable of transmitting calories to said elements. In addition, the invention also relates to elements which can be polymerized other than by thermal means, in particular by chemical means. For this, it is sufficient to equip the device with means to cause the hardening in situ of said elements, by appropriate supply of a reagent. In the embodiment illustrated in FIG. 14, the filter envelope is made up of several independent sections (sleeves), two of which - referenced 4a, 4b - are shown. They are placed end to end, their end zones overlapping the annular elements 3.

Thanks to this arrangement, the radial expansion of the sections 4a, 4b, ... does not require their axial contraction concomitant with that of the sleeve 2; thus, if the structure of said sections does not allow their axial shortening, there is simply a reduction in the spacing (free space) separating two neighboring sections at the level of the annular elements 3.

This configuration of the envelope in several distinct parts is possible whatever its structure. It applies in particular to the embodiments of FIGS. 11 or 13. The fact that the envelope is interrupted opposite the annular elements is not a problem, these areas being in any case impermeable.

The invention can also be applied to wells other than petroleum, in particular to gas or water wells.

Claims

1. Device for placing a filter envelope inside a well, characterized in that it comprises:

- a flexible and inflatable tubular sleeve (2), radially expandable under the effect of an internal pressure (P) generated by a fluid; - A series of annular elements (3) also radially expandable and which surround said sleeve (2) being spaced from each other, these elements (3) being made of a material initially flexible, but curable by polymerization;

- a tubular filter envelope (4), surrounding the series of annular elements (3), and also radially expandable; - Means for polymerizing said annular elements (3) when the sleeve is inflated; said sleeve being detachable from the filter envelope (4) and from the annular elements (3) polymerized, after deflation.

2. Device according to claim 1, characterized in that said elements (3) can be polymerized hot by the Joule effect, by means of heating resistors (20) embedded in the sleeve (2).

3. Device according to one of claims 1 or 2, characterized in that said annular elements (3) are housed in grooves (22) formed in the outer wall of the sleeve (2), the assembly having a cylindrical shape .

4. Device according to one of claims 1 to 3, characterized in that the mutual spacing (b) of the annular elements (3) is substantially greater than their axial dimension (a).

5. Device according to one of claims 1 to 4, characterized in that the filter envelope (4) is formed of braided son (40, 41) which allow its axial retraction during its radial expansion.

6. Device according to one of claims 1 to 4, characterized in that the filter envelope (4 ') consists of a flexible and permeable sheet, wound on itself to form an unclosed tube.

7. Device according to one of claims 1 to 4, characterized in that the filter envelope (4 ") consists of several flexible and permeable sheets

(40 ") which are curved and fixed to the periphery of the annular elements (3) so as to partially overlap in the manner of tiles.

8. Device according to one of claims 1 to 7, characterized in that the filter envelope is subdivided into several independent sections (4a, 4b ...) placed end to end, and whose end zones overlap said said annular elements (3).