WO1996001937A1

WO1996001937A1 - Preform, device and method for casing a well

Info

Publication number: WO1996001937A1
Application number: PCT/FR1995/000902
Authority: WO
Inventors: Jean-Louis Saltel; Frédéric SIGNORI
Original assignee: Drillflex
Priority date: 1994-07-07
Filing date: 1995-07-06
Publication date: 1996-01-25
Also published as: FR2722239A1; FR2722239B1; AU2930095A

Abstract

A preform comprises, distributed along its wall, annular curable zones (3) which are radially and outwardly deformable so that they apply against the wall (20) of the well (2), or of the conduit, and which form, after curing, anchoring and sealing locks for the casing. Application: casing of wells, particularly oil wells, or conduits, without using cement.

Description

PREFORM, DISPOSITI F AND METHOD FOR TUBING A WELL

The present invention relates to a flexible preform which is radially unfoldable, and curable in situ, after it has been placed in a well, in particular an oil well, or in a pipe, to form a cylindrical casing there. The invention also relates to the method for setting up, anchoring this preform in the well or in the pipe, and creating a seal between the preform and the well or the pipe.

Preforms are already known, the wall of which is made of flexible material, capable of being folded back on itself so as to have a radial bulk that is significantly smaller than the diameter of the well or of the pipe to be tubed, or to be lined in the case. localized repair. The preform is introduced into the well or into the pipe in the folded state. Once it has been positioned in the desired location, it is deformed radially towards the outside, by introduction inside the preform of an inflation fluid. Under the effect of internal pressure, it takes a cylindrical shape, that is to say a circular section. The preform thus expanded is anchored inside the well or the pipeline by means of a cement which is poured into the annular space separating the external wall of the cylindrical preform from the wall of the well or of the pipeline. The hot curing, by polymerization, of the wall constituting the preform can be carried out either by introduction of a hot liquid inside the preform, or by Joule effect by means of suitable electrical resistors arranged in the preform, by example of electrical wires forming part of the frame of the wall of the preform, impregnated with theπnosetting resin.

International patent application WO 94/21887 relates to the cementing of casing of this type. The cementing of such a preform of this type poses several problems.

First of all, it requires a relatively sophisticated and expensive cementing installation.

Furthermore, the quality of the cement must be perfect, in order to be able to be inserted correctly, and in a homogeneous manner, in the annular interstices, the thickness of which may be very small, separating the wall of the preform from the wall of the well or the pipeline. Finally, cementing is not always very reliable because it is poorly controlled over long lengths.

The objective of the present invention is to propose a preform of the kind described above, which can be put in place and anchored inside the well or the pipe, without having to make use of a cement.

This objective is achieved, in accordance with the invention, thanks to the fact that the preform comprises, along its wall, curable annular zones capable of deforming radially outward to come to bear against the wall of the well or the pipe and which form, after hardening, anchoring and sealing locks for the casing.

Furthermore, according to a certain number of additional, non-limiting characteristics of the invention:

- The preform includes a reserve of hot-polymerizable resin disposed on the inside and capable of migrating radially outward through the wall under the effect of internal pressure;

- It has an elastically deformable outer skin, certain sections of which in the form of sleeves have a capacity for radial deformation which is clearly greater than that of the rest of the skin, these sections producing said latches;

- the easily deformable sections are made of unreinforced elastomer, while the rest of the skin is made of reinforced elastomer;

- Said reserve consists of annular pockets located opposite said sections of easily deformable outer skin;

- Said reserve extends all along the preform, including facing areas of the outer skin that are not easily deformable; the wall of the preform is composed of a core of heat-polymerizable resin and of two skins of elastomeric material, one interior, the other exterior, said reserve containing the resin being delimited by the core and by the skin interior;

- The preform is provided with annular seals surrounding the hardenable zones intended to constitute the locks. The method according to the invention, intended for the installation, the anchoring, and the sealing of a preform as described above inside a well or a pipe , comprises the following steps: a) the preform is introduced in the folded state into a well or a cylindrical pipe, the diameter of which is slightly greater than that of the preform when it is radially deployed; b) a pressurized fluid is introduced inside the preform to bring it to one state which is highly cylindrical; c) causing said annular zones to be deformed towards the outside in order to apply them against the wall of the well or of the pipe; d) the preform and the annular zones are hardened. Advantageously, in step c) the resin contained in the annular pockets is heated so as to liquefy it and cause it to migrate outward under the effect of internal pressure and, in step d), maintains this resin and that constituting the wall of the preform at the polymerization temperature for a sufficient time to obtain the hardening of the assembly.

Other characteristics and advantages of the invention will appear from the description and the appended drawings, which represent, by way of non-limiting examples, preferred embodiments. In these drawings:

- Figure 1 is a schematic sectional view of a preform according to the invention, after introduction and radial deployment, but before anchoring, inside an oil well;

- Figures 2 and 3 are cross sections of the preform in the folded initial state, according to two different folding modes;

- Figure 4 is a view similar to that of Figures 2 and 3, which shows the radially deployed preform, to take a cylindrical shape; - Figure 5 is a partial view, in axial section, of the wall of the preform, at a curable annular zone intended to constitute an anchoring lock, before it has been deformed radially towards the outside;

- Figure 6 is a view similar to Figure 5, showing the preform after deformation and hardening of the lock; - Figure 7 is a schematic view of a stretch of preform deployed, which is equipped with several seals at the annular curable zone intended to constitute an anchor lock;

- Figure 8 is a longitudinal sectional view at the joint, after anchoring and hardening of the preform in a well. - Figures 9 and 10 are views similar to Figures 5 and 6 respectively¬ ment, showing a variant of the preform.

In Figure 1 there is shown a preform 1 according to the invention, which is placed inside an oil well 2, the cylindrical wall of which is referenced 20. The preform is of known type, made of thermosetting material , hot polymerizable, which before being placed inside the well is folded longitudinally so as to have a reduced radial size. The folding can be carried out in "U" as shown diagrammatically in FIG. 2, or in "snail" as represented in FIG. 3.

After positioning over the desired length, inside the well 2, the preform is deployed so as to take a cylindrical shape, as illustrated in FIGS. 1 and 4.

This radial expansion is done by introducing a pressurized fluid into the interior space 100 of the preform. For this, there is provided a pipe 4 sealingly entering the upper end of the preform, the fluid supply being from the surface S of the well. The fluid used can simply be the liquid mud extracted from the well.

The lower end 1b of the preform is naturally closed by suitable closing means.

In the deployed state, the wall 10 of the preform therefore has a strictly cylindrical shape, of calibrated diameter. The diameter of its outer surface is chosen so as to be very slightly less than the diameter of the wall of the well.

By way of non-limiting example, the external diameter of the preform will be 178 millimeters, while the diameter of the wall 20 will be 184 millimeters.

There is therefore an annular clearance j whose radial value is, for example, 3 millimeters. This free annular space over the entire height of the preform makes it possible to evacuate the mud during inflation.

According to an essential characteristic of the invention, the preform 1 is provided with several curable annular zones distributed along its wall, capable of deforming radially outward to come to bear against the wall 20 of the well so as to form , after hardening, anchoring and sealing locks for the casing. These locks are shown in broken lines and referenced 3 in FIG. 1.

The different latches 3 are spaced apart by predetermined distances Li, L ₂ , which are not necessarily equal.

As an indication, the preform has a length of up to 3000 meters.

The spacing of the locks 3 may be between 5 and 50 meters, for example.

The height of the locks will be of the order of 0.5 to 3 meters. In the embodiment shown in FIGS. 5 and 6, the wall 10 of the preform consists of a thermosetting core 5 sandwiched between an inner skin 6 and an outer skin 7. The core 5 is a heat-polymerizable resin, inside which is embedded a reinforcing reinforcement composed of fibers 50, such as glass or carbon fibers, some circumferential and others longitudinal.

The inner skin 6 is made of unreinforced elastomeric material (synthetic rubber). The outer skin 7 is made of elastomeric material, reinforced by a slightly stretchy fabric.

The annular zone intended to constitute the lock forms a reservoir (pocket) delimited on the one hand by the core 5 and on the other hand by a bulge 6 ′, directed towards the interior 100 of the preform, of the interior skin 6 This tank contains a resin 60, polymerizable hot.

Opposite the bulge 6 ', the outer skin 7 is interrupted to be replaced by a sleeve 8. The latter is suitably connected and fixed, for example by gluing, to the skin 7. The sleeve 8 is made of unreinforced elastomeric material. It is therefore radially expandable, unlike the rest of the outer skin 7. As an indication, the thickness of each of the skins 6, 7 is of the order of 2 millimeters, while the core 5 has a thickness of between 5 and 15 millimeters.

The resin 60 is chosen to have a high viscosity at room temperature, and a low viscosity at high temperature, for example from around 80 ° C. It then becomes liquid and capable of migrating through the core 5 and its frame 50, towards the outside.

The preform is anchored in the well as explained below.

We first proceed to the radial deployment of the preform, by introducing the liquid L, as already said above. The preform will therefore gradually take on a cylindrical shape, while the mud present inside the well is expelled from the annular space which remains free and rises to the surface. It is moreover this same mud which can be used as inflation fluid L, via an ad hoc pumping circuit.

The pressure of the liquid L is chosen so that there is a relatively high pressure difference, for example of the order of 10 bars, between the liquids inside and outside the preform. The preform is retained in its correct position inside the tube by an appropriate device installed on the surface, and not shown.

Next, the wall of the preform is heated, either by replacing the liquid L with a hot liquid, or by Joule effect, using appropriate electrical resistors mounted in the preform. This supply of heat will fluidize the resin 60 contained in the pockets 6 ′, as well as that of the core 5. Under the effect of the pressure p of the interior fluid, the liquid resin will then migrate from the interior to the exterior, while driving the resin constituting the core 5, through the latter to form annular hernias 61 which will be applied - by means of skin sections 8 which are easily deformable - against the wall 20, with a relatively high pressure. Of course, the capacity of the reservoirs and, correspondingly, the volume of the resin 60 are chosen to be sufficient to correctly fill the annular space corresponding to the clearance j, and sufficiently deform the latches 3 outwards against the wall 20. The sections 8, after radial expansion, are referenced 8 'in the drawings. We then continue to provide the preform and the lock with the necessary calories, for a sufficient time - generally a few hours - to obtain the polymerization of the entire wall, including that of the locks.

A rigid casing with a cylindrical inner wall is therefore obtained, the outer wall of which is formed of annular beads which constitute zones for anchoring and sealing the casing in the well 2.

The final operations consist in removing the liquid inside the preform, in removing the conduit 4, and in eliminating the ends of the high la and low lb preform.

The part 1a can be removed simply by transverse sawing. The lower part 1 b can be removed by axial drilling inside the casing.

It should be noted that the location of the latches 3 is perfectly controlled as a result of the presence of the sleeves 8, the aptitude for radial extension of which is greater than the rest of the outer skin 7.

The deformation of the inner skin 6 towards the outside, at the end of the migration of the resin towards the outside, is limited because this skin 7 will come to bear against the filamentary structure 50 of the core 5. Thus, one is ensured that the inner wall of the casing will have a strictly cylindrical shape over its entire height.

The annular locks will be positioned on demand, according to the physical characteristics of the tube well, along the preform, in particular according to the arrangement of certain aquifer zones.

To improve the seal between the preform and the wall of the well, it is possible to provide, at the locks 3, seals.

This possibility is illustrated in Figures 7 and 8. The expandable sleeves 8 are furnished with one or more seals 9, for example three in number. These are for example flexible seals, capable of deploying radially at the same time as the preform, to take a toric shape. After radial expansion and hardening of the latches, the seals are housed in an annular groove in the outer skin 8 ', ensuring a perfect seal at this level. This sealing technique is the subject of patent application no. ^C 94 03629 filed by the applicant on March 23, 1994. It is applied here to the anchoring zones of the preform.

It should be noted that the resin 60 can remain trapped for a long time inside the pockets 6 ′, without risk of degradation.

Thus, the preforms can be stored without damage, put in place at the right time, then anchored also at the right time. Moreover, it is not necessary to carry out the polymerization of the preform and of the latches just after the radial deployment of the preform. These operations can be carried out successively at the appropriate time, in particular depending on the availability of the personnel assigned to these tasks.

In the variant of preform illustrated in FIGS. 9 and 10, in which the same references as in FIGS. 5 and 6 have been used to designate identical or similar elements, the reserve of hot-polymerizable resin 600 is not confined in pockets. On the contrary, it occupies an annular space, between core 5 and inner skin 6, which extends all along the preform 7, including vis-à-vis reinforced outer skin areas, and not easily deformable (see figure 9). During the application of the internal pressure p, the liquid resin will migrate inside the core 5. However, towards the outside, it will only emerge in relation to the easily deformable sections 8, forming at this level the anchoring beads 8 '.

This variant of preform has a lower cost price than that of a pocket preform.

As an indication, the outer skin 7 has a thickness of the order of 2 to 3 mm, the core 5 a thickness of between 5 and 15 mm, the resin 600 a thickness of the order of 0.4 mm and the inner skin 6 a thickness of the order of 2 mm.

Although in the embodiment of the invention which has just been described with reference to the drawings, we are dealing with casing of a vertical well, and more precisely of an oil well, the present invention s 'also applies to the casing of underground wells, which are not necessarily vertical, and to the casing of pipelines, for example pipelines or gas pipelines with a view to their repair in situ by fitting an internal lining.

Claims

1. Flexible preform unfoldable radially and curable in situ after installation in a well or a pipe to form a cylindrical casing, characterized in that it comprises along its wall annular zones hardened (3) capable of deform radially outwards to come to bear against the wall (20) of the well (2) or of the pipe and which form, after hardening, anchoring and sealing locks for the casing.

2. Preform according to claim 1, characterized in that it comprises a reserve of heat-polymerizable resin (60, 600) disposed on the inner side and capable of migrating radially outward through the wall (10), under the effect of internal pressure (p).

3. Preform according to one of claims 1 or 2, characterized in that it comprises an elastically deformable outer skin (7) of which certain sections (8, 8 ') in the form of sleeves, have a capacity for radial deformation significantly larger than that of the rest of the skin (7), these sections producing said latches (3).

4. Preform according to claim 3, characterized in that the easily deformable sections (8, 8 ') are made of unreinforced elastomer, while the rest of the skin (7) is made of reinforced elastomer.

5. Preform according to claim 2 on the one hand, and 3 or 4 on the other hand, taken in combination, characterized in that said reserve consists of annular pockets located opposite said sections (8) of easily deformable outer skin .

6. Preform according to claim 2 on the one hand, and 3 or 4 on the other hand, taken in combination, characterized in that said reserve (600) extends all along the preform, including opposite the zones of outer skin not easily deformable.

7. Preform according to one of claims 5 or 6, characterized in that the wall of the preform is composed of a core (5) of heat-polymerizable resin and two skins of elastomeric material, one inside (6) , the other exterior (7), said reserve containing the resin (60, 600) being delimited by the core (5) and by the interior skin (6).

8. Preform according to claim 7, characterized in that the core (5) comprises a filamentary reinforcement (50) embedded in the resin.

9. Preform according to one of claims 1 to 8, characterized in that it is provided with annular seals (9) surrounding the hardenable zones (3) intended to constitute the latches.

10. Method for setting up, anchoring and sealing a preform according to one of the preceding claims in a well or a cylindrical pipe, according to which: a) the preform (1) is introduced in the state folded in the well (2) or the pipe, the diameter of which is slightly larger than that of the preform when it is radially deployed; b) introducing a pressurized fluid inside the preform (1) to bring it to the strictly cylindrical state; c) causing said annular zones (3) to be deformed towards the outside in order to apply them against the wall (20) of the well (2) or of the pipe; d) causing the preform (1) and the annular zones (3) to harden.

1 1. Method according to claim 10, applied to a preform according to one of claims 5 or 6, characterized in that in step c) the resin (60) contained in the annular pockets is heated so as to liquefy it and migrate it outwards under the effect of internal pressure (p) and that in step d) this resin and that constituting the wall of the preform are kept at the polymerization temperature for a sufficient time to harden the whole.