FR2856456A1 - SEALING DEVICE FOR THE TEMPORARY SHUTTERING OF A WELL OR A PIPELINE. - Google Patents

Abstract

This device comprises a tubular membrane (3) of circular section, with a wall (30) made of waterproof, flexible and elastic material, for example rubber, inflatable and radially deformable outwards under the action of an internal fluid pressure. , this membrane (3) being mechanically reinforced by at least one sheet of flexible son (6; 7); it is remarkable in that it comprises at least one layer, and preferably a pair of adjacent and concentric cylindrical fibrous layers (8, 9), embedded within the wall (30), internally with respect to the web of flexible threads (6; 7), and whose structure acts as an anti-extrusion barrier, limiting the flow of the material of the wall (30)) and preventing it from passing between said reinforcing threads (6, 7), from the inside to the outside, under the effect of the pressure generated by the inflation fluid Temporary sealing of oil well casings and various pipelines.

Description

I

  The present invention relates to a sealing device intended to ensure the temporary sealing of a well, in particular of oil, or of a pipeline.

  Such a device, well known in the technical field of drilling and exploitation of petroleum deposits, is usually designated by the English term "packer".

  It is intended to temporarily separate one from the other two contiguous portions of the well or the pipeline, for example to carry out investigations or repairs in one of these portions.

  The invention relates more particularly to such a sealing device in the form of an inflatable bladder, carried by a support intended to be introduced into the well or the pipe, comprising an inflatable tubular membrane, of circular section, with a wall in waterproof, flexible and elastic material, radially deformable towards the outside under the action of an internal fluid pressure, in order to be applied hermetically against the wall of the well or the pipe.

  At rest, the diameter of the device and of the membrane is less than that of the well or the pipe.

  Once the device has been positioned in the desired area, the inflation of the membrane is generally carried out by pumping a liquid, in particular water, a hydrocarbon, and / or the mud present inside the well or pipeline.

  This fluid is brought to a high pressure, capable of causing the expansion of the membrane and pressing it firmly against the wall of the zone in question in order to seal it hermetically temporarily.

  Once the investigation and / or repair operations have been completed, the membrane is deflated and the device is removed.

  It can of course be used again later to close off a new area of the same well or the same pipe, or be transferred to another site, in a new well or in a new pipe, to fulfill the same function there.

  As an indication, in an application in the petroleum field, the membrane generally has a length of the order of approximately 1 to 4 m, an initial external diameter (non-swollen membrane) comprised within a range of approximately 70 mm to 150 mm, and a wall thickness (non-swollen membrane) within a range of approximately 15 mm to 25 mm.

  The material of the membrane is generally natural or synthetic rubber.

  Proper inflation of the membrane requires the implementation of a relatively high internal pressure, the value of which, still for information only, is usually of the order of 3,107 to 4,107 Pascal (30 to 40 MPa).

  The wall of the membrane is therefore exposed during inflation to very high forces which risk damaging it, or even causing it to explode.

  This is why it is generally reinforced mechanically. Conventionally, this reinforcement is provided by at least one ply of flexible wires, for example of steel, embedded in the thickness of its wall, this ply being inscribed in a cylindrical surface of revolution coaxial with said membrane.

  In a known embodiment, there is provided a pair of concentric reinforcement plies, each composed of a series of parallel flexible wires (or cables), for example of steel, wound helically with a high pitch (that is 20 to - say with a slight inclination relative to the longitudinal axis of the device), the inclinations of the wires of the two layers having an inclination with a value of an angle which is close, but in opposite directions.

  This angle is initially (non-swollen membrane) of the order of 15 for example; it increases during inflation of the membrane to reach a final value of the order of 35 to 40.

  In the devices developed, there is provided at least a third similar ply (auxiliary ply), arranged coaxially with the other two, towards the inside of the membrane, but composed of threads thinner and closer to each other than those of the plies. (main) exterior.

  The function of this auxiliary sheet is to oppose the so-called extrusion phenomenon, linked to the creep of the material constituting the wall of the membrane, from the inside to the outside, under the action of internal pressure very high, which risks causing the formation of a hernia passing through the interstices between certain reinforcing wires of the main plies and leading to a rupture of the wall.

  This solution is relatively satisfactory, but does not however completely eliminate the risk of extrusion of the material nor, correlatively, deterioration of the membrane.

  The present invention aims to solve this problem by proposing to provide the membrane with a structure capable of eliminating, or practically eliminating, such a risk.

  To this end, and in accordance with the invention, the sealing device which is the subject thereof, comprises at least one fibrous layer, called filter layer, which also has a cylindrical shape of revolution, and is arranged concentrically and embedded within the membrane wall, internally with respect to the ply, or plies, of flexible wires, and this filter layer has a structure which acts as an anti-extrusion barrier, adapted to limit the creep of the material constituting the membrane wall and prevent it from passing between the reinforcing threads, from the inside to the outside, under the effect of the pressure generated by the inflation fluid.

  In a preferred embodiment, the device comprises at least one pair of adjacent fibrous layers, called filter layers, which also have a cylindrical shape of revolution, and are arranged concentrically one inside the other and are embedded within the membrane wall, internally with respect to the ply, or plies, of flexible son, and this pair of filter layers has a structure which acts as an anti-extrusion barrier, adapted to limit the creep of the constituent material of the wall of the membrane and prevent it from passing between the reinforcing threads, from the inside to the outside, under the effect of the pressure generated by the inflation fluid.

  Furthermore, according to other advantageous and non-limiting characteristics of the invention: - each of said filter layers is composed of a multitude of very fine fibers which extend parallel to one another, forming a helix with pitch very large, of direction slightly inclined with respect to the axis of revolution of the membrane; - The constituent fibers of the two filter layers are inclined at the same acute angle relative to said axis of revolution of the membrane, but in the opposite direction; - The acute angle that these fibers form with respect to said axis of revolution is between 5 and 15 o; - Said fibers are made of a material having a high mechanical tensile strength, such as, in particular, aramid, carbon or glass fibers; - Said fibers have a circular section whose diameter is between 5 and 20 micrometers approximately, and is preferably of the order of 10 to 12 micrometers; - considered in a cross sectional plane with said fibers, their density is of the order of 10 000 / mm2; each of said filter layers has a thickness of the order of 10 0.4 to 0.8 mm.

  Other characteristics and advantages of the invention will appear on reading the following description of a preferred embodiment of the invention.

  This description is made with reference to the accompanying drawings in which FIGS. 1 to 5 are intended to illustrate an explanation relating to the sealing devices of the same general type as that forming the subject of the invention, FIGS. 6 to 10 represent a mechanically reinforced membrane according to the state of the art and FIGS. 11 to 14 represent a membrane having the characteristics of the invention.

  - Figure 1 shows, axially cut, and very schematically, a sealing device which has been positioned inside a well or a pipe, in an area which must be closed, its membrane n 'not yet swollen; - Figure 2 is a view similar to that of Figure 1, after inflation; - Figures 3 and 4 are views showing the membrane before and after inflation, in cross section, the cutting planes being referenced respectively III-III and IV-IV in Figures 1 and 2; - Figure 5 is a view similar to Figure 2, which shows a variant of the device; - Figures 6 and 7 are partial views, in cross section, respectively before and after inflation, of the reinforced wall of a membrane of known type which is provided with a device as shown in the previous figures; - Figures 8 and 9 are diagrams illustrating the angular position of the reinforcing son of this wall, respectively before and after inflation; - Figure 10 is a view similar to that of Figure 7, intended to illustrate a phenomenon of material extrusion, a phenomenon which the invention proposes to eliminate; - Figures 11 and 12 are views similar to those of Figures 6 5 and 7, respectively, showing the reinforced wall of a membrane which is provided with a sealing device according to the invention; - Figures 13 and 14 are diagrams illustrating the angular position of the fibers of the filter layers, respectively before and after inflation of the membrane.

  In Figure 1, there is designated by the reference T a cylindrical casing or casing lining the interior of a well or a pipe, of axis Z-Z '.

  Although disposed horizontally in the figure, this axis can, of course, have any other orientation, in particular oblique or vertical.

  The sealing device 1 essentially comprises a support consisting of a pair of end washers 2a, 2b between which is arranged a membrane 3 in the form of a sleeve, of circular section.

  This sleeve is made of a composite material, comprising a mechanical reinforcement frame embedded in a matrix of flexible and elastically deformable material, for example rubber. Its end portions are tightly fixed to the washers 2a, 2b, which close these ends.

  Means not shown, of known type, allow, on the one hand, to move the device inside the tube T, in order to be able to position it opposite the area to be closed, and, on the other hand, to introducing a fluid, in particular a liquid, under a high pressure inside the tubular membrane 3, via a channel 20 drilled for this purpose in one (2a) of the washers.

  As illustrated in FIG. 2, in which the introduction of the liquid is symbolized by the arrow F, the pressure Pi developed by the latter has the effect of expanding the membrane radially outwards, so that it s' apply firmly and intimately against the internal wall of the tube T. The desired obturation is thus obtained. During this radial expansion, a decrease in the length of the membrane is observed, by mutual approximation of the two end washers 2a, 2b, as well as a decrease in the thickness of the membrane.

  Its initial diameter Do (see Figure 3) increases, the diameter D after inflation being of the order of 1.5 x Do to about 2 x Do.

  In the variant of FIG. 5, the device comprises a tubular central mandrel 4 which carries the end washers 40a, 40b, between which the membrane 3 is mounted. The inflation fluid is introduced into the mandrel and arrives at the inside the membrane via radial holes 41 formed in the wall of the mandrel. The end washers 40a, 40b can slide in leaktight manner on this mandrel to adapt to the axial shortening of the membrane during its inflation.

  As shown in Figure 6, the wall 30 of the membrane 3 is reinforced.

  It comprises three plies of flexible wires 5, 6 and 7 embedded in the thickness of its wall.

  These plies each fit into a cylindrical surface of revolution coaxial with the membrane 3, that is to say of axis Z-Z '.

  The wires 5, 6 and 7 are for example steel wires of circular section.

  The inner ply is made of threads 5 whose diameter is significantly smaller than that of the threads 6 of the central ply and 7 of the outer ply.

  As an indication, the diameter of the wires 5 is of the order of 0.5 mm; that of the wires 6 and 7 is of the order of 3 mm.

  In each of the reinforcement plies, the wires which compose it are arranged parallel next to each other, practically in contact with each other, and are wound in a helix around the longitudinal axis ZZ ′ with a high pitch, that is to say with a slight inclination relative to this axis.

  This angle, designated a0 in FIG. 6 initially has (a non-swollen membrane) a value of the order of 15 for example; it increases during inflation of the membrane to reach a final value a (FIG. 9) of the order of 35 to 40.

  As shown in FIGS. 8 and 9, the inclinations of the wires 6 and 7 are substantially the same angle, these having similar values, but the wires are oriented in the opposite direction.

  The finer threads S of the inner ply have an orientation similar to that of the threads 7 of the outer ply.

  It will be observed from FIGS. 6 and 7 that the inflation induces an increase in the radius of curvature of the section of the membrane and a decrease in its thickness, which goes from a value e0 to a smaller value e.

  It also induces, as indicated above, a reduction in its axial length.

  The inclined arrangement of the reinforcing wires 5, 6 and 7 allows the latter to accompany the multidirectional deformation of the wall of the membrane in which they are embedded. These threads oppose an uncontrolled deformation of the membrane by absorbing the very large forces generated by the internal pressure Pi. We also observe an increase in the mutual spacing of two neighboring threads within the same ply.

  The inner layer of threads 5, thinner but denser, has 10 essentially the function, not of absorbing the forces generated by the inflation, but of opposing the phenomenon of extrusion mentioned above.

  However, it does not always do this effectively. With reference to Figure 10, this problem can be explained. The rubber mass is subjected to a very high internal fluid pressure 15 Pi, of the order of 40 MPa, which acts against its internal wall 300.

  In addition, it is often also exposed to high heat, especially in oil drilling applications, which tends to soften it.

  For these reasons, it may happen that in a region of this internal wall 20, the material flows and is discharged towards the outside, by forming a pocket 301.

  This localized thrust of material can first of all cause the mutual spacing of two adjacent wires 5, a spacing which propagates to the neighboring wires 5 and creates a breach in an area 31 of the wall, through the first ply.

  The fault having been formed, the creep of the material can continue, and progress rapidly towards the outside, in the same way separating the wires 6, then 7 from the other layers.

  This creep, which is similar to an extrusion, symbolized by the arrow E in FIG. 10, ends up causing the rupture of the wall and the bursting of the membrane.

  The arrangement according to the invention, schematically illustrated by Figures 11 to 14, solves this problem.

  We find in the structure of the wall a reinforcing reinforcement which, in the example illustrated, is identical to that previously described, composed of two layers of wires 6, 7.

  However, this is not a mandatory provision.

  According to the invention, the inner ply of threads 5 has been replaced by a pair of adjacent fibrous layers 8, 9, which will conventionally be called "filter layers", because they have the function of opposing a barrier filtering the flow of matter to prevent initiation and, correspondingly, the formation of the phenomenon of extrusion which has just been explained.

  These filter layers also have a cylindrical shape of revolution, are arranged concentrically one inside the other, and are embedded within the wall 30 of the membrane 3, internally with respect to the plies of wires 6 and 7. .

  The filter layer 8 is arranged just inside the filter layer 7, which means that there is no material constituting the wall between them.

  They are adjacent, possibly bonded to each other by means of an adhesion film.

  The portions of the wall 30 which are internal and, respectively, external, to the bilayer 8, 9 have been designated by the references 30i and 30e.

  The wires 6, 7 are embedded in the portion 30e, which is adhered around the filter layer 9.

  The portion 30 ;, devoid of reinforcing reinforcement is adhered to the interior of the filter layer 8.

  Each of the filter layers 8, 9 is composed of a multitude of very fine fibers 80, respectively 90, which extend parallel to each other, forming a helix with very large pitch, of direction slightly inclined with respect to the axis of revolution ZZ 'of the membrane (see Figure 13).

  The fibers 80 and 90 are inclined by the same acute angle, or by a neighboring angle, o with respect to said axis of revolution Z-Z 'of the membrane 3, but in the opposite direction.

  This angle / o is advantageously between 5 and 15 O. It is therefore notably smaller than the oro angle of the wires 6 and 7. These fibers are made of a material which is both very flexible and has a high mechanical resistance to traction.

  As a particularly suitable material, mention may be made of aramid fiber.

  The fibers preferably have a circular section and a diameter of the order of 10 to 12 gim. When viewed from a cross-sectional plane, their density is in the order of 10,000 / mm2.

  As an indication, each of these filter layers 8, 9 has a thickness of the order of 0.4 to 0.8 mm.

  The fibers are long filaments grouped into several flat bundles, forming sort of strings in the form of very thin strips (very thin), 5 helically wound one on the other and next to each other, over the entire length of the membrane, this to form each of the two filter layers.

  Because of their low initial inclination / go, the fibers remain loose after radial expansion of the preform, which caused the increase in this inclination, at angle s (see FIG. 80). They are not under tension, 10 unlike the reinforcement wires 6 and 7.

  If we again consider the appearance of the extrusion phenomenon that we wish to combat, the material of the wall portion 30; which is exposed to high pressure and, if necessary, to high heat, tends to creep outward. However, it collides with the fibrous barrier formed by the layer 8. Each fiber 80 absorbs part of the thrust and transmits it to the surrounding fibers. Because of the density of these fibers, the material flow is forced, in order to pass, to clear a baffled path through the microinterstices between fibers. In addition, its pressure decreases due to the absorption of forces by these fibers. The migration of the material is therefore considerably slowed down, or even prevented.

  The second layer 9 supports the first 8. Given the disposition inclined in the opposite direction of its fibers, the radial forces exerted by the first layer 8 are distributed homogeneously over the second 9, which in turn absorbs them.

  As a result of the crossed orientation of the fibers 80 and 90, there is no - or practically no - risk that the fibers are separated from one another in the axial direction, leaving room for the formation of a hernia.

  Matter cannot form a breach. The desired barrier or filter effect is therefore well achieved. In fact, the thrust of the material from the inside to the outside (from part 30i to part 30e) has been controlled, distributed and absorbed upstream by the pair of filter layers 8 and 9.

  There is therefore no risk, a fortiori, that the reinforcing wires 6, then 7, are spaced apart from one another in the axial direction, leaving room for the formation of a hernia.

  These wires 6, 7 can therefore fully play their role of reinforcements, mechanically reinforcing the membrane.

  Although the embodiment of the device which has just been described has a pair of filter layers, it would not go beyond the scope of the invention to provide it with a single filter layer or with more than two filter layers.

Claims (9)

  1. Sealing device (1) for the temporary sealing of a well or a pipe, which comprises, carried by a support (2a-2b; 4, 40a40b), an inflatable tubular membrane (3) of section circular, with wall (30) of tight, flexible and elastic material, radially deformable towards the outside under the action 5 of an internal fluid pressure, in order to be applied hermetically against the wall (T) of the well or the pipeline, this membrane (3) being mechanically reinforced by at least one ply of flexible wires (6; 7) embedded in the thickness of its wall, this ply being part of a cylindrical surface of revolution coaxial with said membrane, characterized by the fact that it comprises at least one fibrous layer (8, 9), called the filter layer, which also has a cylindrical shape of revolution, and is arranged concentrically and is embedded in the wall (30) of the membrane (3), internally with respect to said ply of flexible wires (6; 7), this filter layer (8, 9) having a structure which acts as an anti-extrusion barrier, adapted to limit the creep of the material constituting the wall (30) of the membrane (3) and prevent it from passing between the reinforcing wires (6, 7), from the inside to the outside, under the effect of the pressure (Pi) generated by the inflation fluid.   2. Sealing device (1) for the temporary sealing of a well or a pipe, which comprises, carried by a support (2a-2b; 4, 40a40b), an inflatable tubular membrane (3) of circular section, with wall (30) of tight, flexible and elastic material, radially deformable towards the outside under the action of an internal fluid pressure, in order to be applied hermetically against the wall (T) of the well or the pipe, this membrane (3) being mechanically reinforced by at least one ply of flexible wires (6; 7) embedded in the thickness 25 of its wall, this ply being part of a cylindrical surface of revolution coaxial with said membrane, characterized in that it comprises at least one pair of adjacent fibrous layers (8, 9), called filter layers, which also have a cylindrical shape of revolution, and are arranged concentrically one inside the other and are embedded in the wall (30) of the membrane (3), 30 internally with respect to said ply of flexible wires (6; 7), this pair of filter layers (8, 9) having a structure which acts as an anti-extrusion barrier, suitable for limiting the creep of the material constituting the wall (30) of the membrane (3) and preventing it from passing between the reinforcement wires (6, 7), from the inside to the outside, under the effect of the pressure (Pi) generated by the inflation fluid.   3. Sealing device according to claim 1, characterized in that the filter layer (s) (8, 9) is (are) composed of a multitude of 5 very fine fibers (80, 90) , which extend parallel to each other, forming a helix with very large pitch, of direction slightly inclined with respect to the axis of revolution (Z-Z ') of the membrane (3).   4. Sealing device according to claims 2 and 3 taken in combination, characterized in that the fibers (80, 90) constituting the two filter layers (8, 9) are inclined at the same acute angle (j / 0) relative to said axis of revolution (Z-Z ') of the membrane (3), but in the opposite direction.   5. Sealing device according to claim 4, characterized in that the acute angle (/ go) that the fibers form (80, 90) relative to said axis of revolution (Z-Z ') is between 5 and 15.   6. Sealing device according to one of claims 3 to 5, characterized in that said fibers (80, 90) are made of a material having a high mechanical tensile strength, such as, in particular, fibers of aramid, carbon or glass resin.   7. Sealing device according to claim 6, characterized in that the said fibers (80, 90) have a circular section whose diameter is between 5 and 20 micrometers approximately, and is preferably of the order of 10 at 12 micrometers.   8. Sealing device according to claim 7, characterized in that, considered in a section plane transverse to said fibers (80, 90), their density is of the order of 10 000 / mm2.   9. Sealing device according to one of the preceding claims, characterized in that each of said filter layers (8, 9) has a thickness of the order of 0.4 to 0.8 mm.