Patent Publication Number: US-10781661-B2

Title: Isolation device for a well with a breaking disc

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     The present application is a national phase entry under 35 U.S.C. § 371 of International Application No. PCT/EP2016/066937 filed Jul. 15, 2016, published in French, which claims priority from French Patent Application No. 1501488 filed Jul. 15, 2015, all of which are incorporated herein by reference. 
     FIELD OF THE INVENTION 
     The present invention relates to a device for controlling and isolating a tool, in the form of an expanding liner for treating a well or a pipe, this tool being connected to a casing feeding a fluid under pressure and being interposed between said casing and the wall of said well or of the pipe. 
     Expressed differently, it relates to a downhole system allowing the isolation of the upstream space from the downstream space of an annular region comprised between a casing and the formation (in other words subsurface rocks) or between the same casing and the inner diameter of another casing already present in the well. This isolation must be accomplished while still preserving the integrity of the entire casing string, i.e. to say the steel column comprised between the formation and the well head. 
     It will be noted that it is necessary to distinguish the integrity of the annular space and the integrity of the casing, both being essential to the integrity of the well. 
     The annular space previously mentioned is generally sealed by using a cement which is pumped in liquid form into the casing from the surface, then injected into the annular space. After injection, the cement hardens and the annular space is sealed. 
     The quality of the cementation of this annular space assumes a very great importance for the integrity of the well. 
     In fact, this sealing protects the casing from the salt water zones contained underground, which can corrode and damage them and possibly bring about the loss of the well. 
     Moreover, this cementation protects the aquifers from pollution that could occur from nearby formations containing hydrocarbons. 
     This cementation constitutes a barrier protecting from the risks of eruption caused by gas at high pressure which can migrate into the annular space between the formation and the casing. 
     In practice, there are numerous reasons which can lead to an imperfect cementation process, such as the large size of a well, its horizontal zones, difficult circulation or loss zones. The result is poor sealing. 
     It will also be noted that wells are deeper and deeper, that a good number of them are drilled “offshore” above water depths which can reach more than 2000 m, and that the latest hydraulic fracturing technologies in which pressures can reach more than 15,000 psi (1000 bars) subject these sealed annular zones to very high forces. 
     From the preceding, it is clear that the cementation of the annular space(s) is particularly important and any weakness in its accomplishment, when the pressures in question are very high (several hundred bars), can cause damage which can lead to the loss of the well and/or cause considerable ecological damage. 
     The pressures in question can come from: 
     the inside of the casing toward the outside, i.e. from inside the well toward the annular space; 
     the annular space toward the inside of the casing. 
     The casing (or casing string), the length whereof can attain several thousand meters, consist of casing tubes, with unit lengths comprised between 10 and 12 m, assembled to one another by sealed threads. 
     The nature and the thickness of the material constituting the casing are calculated to withstand very high inner bursting pressures or outer collapsing pressures. 
     Moreover, the casing must be sealed throughout the duration of the life of the well, i.e. during several decades. Any detection of a leak leads systematically to repair or abandonment of the well. 
     Technical solutions are currently available to accomplish sealing of said annular space. 
     PRIOR ART 
     Numerous isolation systems have already been proposed and are current used for this purpose. 
     Document U.S. Pat. No. 7,571,765 describes a system comprising a rubber ring compressed and expanded radially by hydraulic pressure via a piston, to come into contact with the wall of the well. In use, however, these systems do not allow sealing a well having a section that is not a cylinder of revolution and are very sensitive to variations in temperature. 
     Mechanical isolation systems have been proposed based on swellable elastomers made of a polymer of the rubber type activated into swelling by contact with a fluid (oil, water or other, depending on the formulations). To avoid blockage of the tube during insertion down the well, the swelling must be relatively slow and may sometimes require several weeks for the isolation of the zone to be effective. 
     Other types of isolation systems are made of an expandable metal liner deformed by the application of liquid under pressure (see article SPE 22 858 “Analytical and Experimental Evaluation of Expanded Metal Packers For Well Completion Services (D. S. Dreesen et al—1991), U.S. Pat. Nos. 6,640,893, 7,306,033, 7,591,321, EP 2 206 879, EP 2 435 656). 
     Shown schematically is the general structure of a known system of this type in the appended  FIGS. 1 and 2 . 
     As can be seen in  FIG. 1 , to create an annular isolation system intended for sealingly isolating two adjoining annular spaces, referred to as EA 1  and EA 2 , of a well or formation, the wall whereof is referred to as P, one known technique consists of positioning a deformable ductile membrane  10  of cylindrical geometry around a casing  20  at the desired position. 
     The membrane  10  is attached and sealed at its ends on the surface of the casing  20 . A liner in the form of a ring between the outer surface of the casing  20  and the inner surface of the membrane  10  is thus defined. The inside of the casing  20  and the inner volume of the liner formed by the membrane  10  communicate with one another through a passage  22  passing through the wall of the casing  20 . 
     The membrane  10  is then expanded radially toward the outside until it is in contact with the wall P of the well, as can be seen in  FIG. 2 , by increasing the pressure P 1  in the casing  20 . The membrane  10  forms a seal on this wall P, and the two annular spaces EA 1  and EA 2  defined between the wall P and the formation and the wall of the casing  20  are then isolated. 
     The membrane  10  can be made of metal or out of elastomers, reinforced with fibers or not. 
     Although they have already led to much research, systems of the type illustrated in appended  FIGS. 1 and 2  have several disadvantages. 
     If the membrane  10  is made of elastomers and the circulation of the inflating fluid is accomplished without a valve in the passage  22 , the membrane resumes a shape near to its initial state if pressure is released inside the casing after having inflated it. The membrane  10  then no longer serves to isolate the annular space. 
     If the membrane  10  is metallic and the circulation of the inflating fluid between the inside of the membrane  10  and the inside of the casing  20  is accomplished directly, once permanently deformed, the membrane  10  retains in principle its shape, and its function as a barrier in the annular space is also retained when the pressure in the casing  20  is released. If, however, the pressure increases in the annular space, on the side EA 1  for example, the pressure differential between EA 1  and the inside of the membrane  10  can be sufficient to collapse the metallic membrane  10 . This will then no longer retain its role of isolating the annular space. 
     To avoid this, in the case of a membrane  10  made of metal or elastomers, the opening  22  allowing the circulation of the inflating fluid between the inside of the casing  20  and the inside of the membrane  10  can be provided with a non-return valve. This valve traps the inflating volume under pressure inside the membrane  10  at the conclusion of inflation. Nevertheless, if the temperature and/or the pressure in the annular space change, the volume inside the membrane can also change. If the pressure decreases, the membrane  10  can collapse or lose its sealing contact with the wall P of the well. The function of isolation of the annular space is then no longer ensured. If, on the other hand, the pressure increases, the membrane  10  can deform to the breaking point. If the membrane  10  does not break, there is a risk that the pressure will increase enough inside the membrane  10  to collapse the wall of the casing  20 . 
     To avoid this risk there has been proposed, for example in document US 2003/0183398, in addition to the first opening  22  provided with a non-return valve, a second opening provided between the membrane  10  and the high pressure zone EA 1 , which incorporates a valve. The latter allows creation of an opening between the inside of the membrane  10  and the high pressure zone EA 1  at the conclusion of inflation. In this manner, the changes in the temperature of the well or of the pressure on the side EA 1  no longer have an effect on the pressure inside the membrane  10  because the membrane  10  is in communication with the annular space. 
     During inflation, the pipes are held open using rupturing pins which are configured to yield when a limiting value of shear is attained. 
     Nevertheless, these rupturing pins have reliability problems. Document SPE-169190-MS ( Improved Zonal Isolation in Open Hole Applications,  2014) gives dimensions comprised between 1.15 and 1.30 mm for breaking pressures comprised between 4500 and 6800 psi (310 and 470 bars). The diameter of the pins is therefore very small, thus creating technical difficulties in manufacture. In addition, it is noted that, for a given value, important dispersions are observed (for example, for 1.19 mm pin, breaking pressures of the samples tested extend from 4600 to 5100 psi (320 to 350 bars)). 
     Due to their relatively small dimensions (on the order of a millimeter), it has thus proven difficult to obtain pins for which the breaking pressure is known with precision. 
     OBJECT OF THE INVENTION 
     The goal of the invention is to propose a device that makes it possible to resolve the aforementioned problems. 
     The invention proposes a fluid control device for treating a well, comprising an expandable liner placed on a casing and an assembly adapted to control the feeding of the inner volume of the liner using a fluid under pressure coming from the casing through a passage passing through the wall of the casing, to expand the liner radially outward, the assembly comprising a valve, said valve comprising:
         a body which defines a chamber into which lead
           a communication pipe associated with the inside of the casing,   a pipe associated with the inside of the expandable liner and   a pipe associated with the annular space located outside the casing, said pipe being located in the extension of the chamber,   
           a piston translatably mounted in said chamber and   releasable immobilization means which can break, on which, in an initial state, one end of the piston comes into abutment and which, in an initial position, close the pipe associated with the annular space, the immobilization means being releasable under the influence of the pressure of the fluid in the chamber which is equal to the pressure of the fluid in the liner,   a closure member translatably mounted in said chamber, configured to open or close the communication pipe with the inside of the casing, said closure member being, in the initial state, in contact with another end of the piston which holds it in the open position,   so that, in the initial state, the piston allows only communication between the pipes associated with the inside of the casing and the inside of the expandable liner,   then, after breaking of the releasable immobilization means, the piston is released in translation through the releasable immobilization means,   so that, in the final state the pipe associated with the annular space located outside the casing is open and the closure member is no longer held in the open position by the piston.       

     Thanks to this device, it is possible to dispense with the use of a breaking pin thanks to a disc configured to hold the piston and also to break under the influence of the pressure of the fluid. 
     The use of the disc that breaks under the influence of the pressure in the chamber (and therefore in the inner volume of the liner) allows good precision, while still retaining the abutment role of the rupturing pin of the prior art. 
     The device can comprise the following features, taken alone or in combination:
         The device also comprises a spring which drives the closure member into the closing position to close the communication pipe with the inside of the casing when the immobilization means are broken,   the device further comprising a measurement system configured to measure the position of the piston in said chamber, so that it is possible to know the state of the device,   the measuring system comprises a magnet located in the piston and a sensor located in the housing, said sensor being capable of measuring a displacement of said magnet.       

     In addition, this device is advantageously inserted into a double back to back non-return valve system which prevents, once inflation is concluded, any communication between the inside of the casing and the liner and which allows communication of the liner with the annular space. 
     For this purpose, the invention proposes an isolation system for treating a well, comprising a device as previously described and characterized by the fact that said assembly comprises a non-return valve placed in a passage which connects the inner volume of the casing to the inner volume of the liner, said fluid control device and said non-return valve forming, after switching, two valves mounted in series and with opposite directions in the passage connecting the inner volumes of the casing and the liner. 
     The system can comprise the following characteristics, taken alone or in combination:
         the non-return valve placed in the passage connecting the inner volume of the casing to the inner volume of the liner is a valve biased elastically to closure, which opens under a fluid pressure which is exerted in the direction running from the inner volume of the casing to the inner volume of the liner.   the valves are non-return valves in which a metal closure member rests on a metal seat,   the valves are non-return valves with a conical seat,   the valves comprise a seal adapted to rest against a complementary bearing when the valve is in its closing position or near its closing position,   the seal is provided on the closure member and is adapted to rest against a complementary bearing formed on the body housing the valve and forming the seat, or is provided on the body housing the valve and forming a seat and is adapted to come into contact against a complementary bearing formed on the closure member,   the non-return valve placed in the passage which connects the inner volume of the casing to the inner volume of the liner and the device are formed from two distinct sub-assemblies,   the non-return valve placed in the passage which connects the inner volume of the liner and the device are placed in distinct parallel longitudinal channels formed in the body of the assembly.       

     The invention also proposes an assembly comprising in combination a non-return valve and a device as described previously, forming, after switching, two valves mounted in series and with opposite directions, back to back, on the passage connecting the inner volumes of a casing and a liner of a well isolation device. 
     The valves can be non-return valves in which a metal closure member rests on a conical metal seat. 
     Finally, the invention proposes a method for isolating two annular zones of a well, implementing 
     a step of feeding an expandable liner placed on a casing using a fluid under pressure coming from the casing, to expand the liner radially outward, characterized by the fact that it comprises the steps of 
     feeding the inner volume of the expandable liner by means of a non-return valve placed in a passage which connects the inner volume of the casing to the inner volume of the liner, then 
     carrying out the switching of a system as previously defined between an initial state in which a connection is established between the inner volume of the casing and the inner volume of the liner to expand said liner and a final state in which the connection between the inner volume of the casing and the inner volume of the liner is interrupted and a connection is established between the inner volume of the liner and an annular volume of the well outside of the liner and of the casing, said device and said non-return valve forming, after switching, two valves mounted in series and with opposite directions on the passage connecting the inner volumes of the casing and the liner. 
    
    
     
       PRESENTATION OF THE FIGURES 
       Other features, aims and advantages of the present invention will appear upon reading the detailed description which follows, and with respect to the appended drawings, given by way of non-limiting examples and in which: 
         FIGS. 1 and 2  described previously show an annular isolation device conforming to the prior art, respectively before and after expansion of the expandable liner, 
         FIGS. 3, 4 and 5  show a device conforming to the present invention respectively at the initial state, in the expansion phase of the expandable liner by communication between the inner volume of the casing and the inner volume of the liner, then in the final sealed state after switching of the three-way valve providing the connection between the inner volume of the liner and the annular volume of the well outside of the liner and of the casing. 
         FIGS. 6 and 7  show schematically an assembly conforming to a first variant embodiment of the present invention comprising, in combination, a three-way valve and a non-return valve at the input, respectively at the initial position and in the final switched position, 
         FIG. 8  shows the equivalent schematic of the switched assembly illustrated in  FIG. 7 , 
         FIG. 9  shows an axial section view running through a channel which houses an input valve, 
         FIGS. 10 to 12  show a more general embodiment of the invention 
         FIG. 13  illustrates a head-to-tail assembly of two insulation devices conforming to one embodiment of the invention, on a casing, to guarantee isolation between two adjoining annular zones of a well, whatever changes occur relating to pressure in the two annular zones, 
         FIGS. 14 through 16  show a more general embodiment of the invention, 
         FIGS. 17 and 18  show an embodiment of the invention with a system for measuring the displacements of the piston. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The device that is the object of the invention finds application in a particular system of valves which will be described in detail as an illustration. Nevertheless, said device can be inserted into other types of systems, possessing other features. It will be described below. 
     An isolation system conforming to the present invention is observed in the appended  FIG. 3 , comprising an expandable liner  100  placed on a casing  200 , facing a passage  222  passing through the wall of the casing  200  and an assembly  300  adapted to control the expansion of the liner  100 . The assembly  300  comprises an input non-return valve  400  and a three-way valve  500  adapted to be switched once and forming, after switching, in combination with the input valve  400 , two non-return valves mounted in series and with opposite directions on a passage connecting the inner volume  202  of the casing  200  and the inner volume  102  of the liner  100 . 
     The liner  100  is advantageously formed from a cylinder of revolution metal envelope engaged on the outside of the casing  200  and of which the two axial ends  110 ,  112  are sealingly connected to the outer surface of the casing  200  at its two axial ends  110  and  112 . 
     Once the isolation system thus formed is introduced into a well P so that the liner  100  is placed between two zones EA 1  and EA 2  to be isolated, the assembly  300  is adapted to initially ensure the feeding of the inner volume  102  of the liner  100  using a fluid under pressure coming from the casing  200 , through the passage  222  passing through the wall of the casing  200 , to radially expand the liner  100  outward as can be seen in  FIG. 4 . 
     More precisely, according to the invention, said assembly  300  comprises a non-return valve  400  placed in the passage  222  which connects the inner volume  202  of the casing  200  to the inner volume  102  of the liner  100  and means  500  forming a three-way valve adapted to be switched only once between an initial state corresponding to  FIG. 4 , wherein a connection is established between the inner volume  202  of the casing  200  and the inner volume  102  of the liner  100  to expand said liner  100  and a final state corresponding to  FIG. 5 , wherein the connection between the inner volume  202  of the casing  200  and the inner volume  102  of the liner  100  is interrupted, while a connection is established between the inner volume  102  of the liner  100  and an annular volume EA 1  of the well P outside of the liner  100  and of the casing  200 , so as to avoid the collapse of the membrane composing the liner  100 , particularly under the pressure of the annular volume EA 1 . In fact, the inner volume  102  of the liner  100  being subjected to the same pressure as the annular volume EA 1 , the liner  100  is not affected by possible changes in pressure in the annular volume EA 1 . 
     An assembly  300  is noted in  FIG. 6  conforming to a first variant embodiment of the present invention comprising in combination a three-way, two position valve  500  and an input non-return valve  400 . 
     The non-return valve  400  is placed in a pipe coming from the inner volume  202  of the casing  200  and leading to a first path  502  of the valve  500 . It comprises a body which defines a conical seat  410  tapered moving away from the input coming from the inner volume  202  of the casing  200 , a closure member  420  placed downstream of the seat  410  with respect to a fluid feed direction extending from the inner volume  202  of the casing  200  toward the inner volume  102  of the liner  100  and a spring  430  which drives the closure member  420  into sealing contact against the seat  410  and thereby which biases the valve  400  to closure. 
     The seat  410  and the closure member  420  are advantageously made of metal defining a metal/metal valve  400  with sealing means. 
     At rest the valve  400  is closed under the bias of the spring  430 . When the pressure exerted from upstream to downstream by a fluid, applied from the inner volume  202  of the casing  200 , exceeds the setting force exerted by the spring  430 , this pressure presses back the closure member  420  and opens the valve  400 . On the other hand, any pressure exerted from downstream to upstream, i.e. from the inner volume  102  of the liner  100 , tends to reinforce the bias of the closure member  420  against its seat and therefore the valve  300  to closure. 
     The two other paths  504  and  506  of the valve  500  are connected respectively with the inner volume  102  of the liner  100  and the annular volume EA 1  of the well P. 
     In the initial state shown in  FIG. 6 , the valve  500  provides a connection between the paths  502  and  504  and consequently between the output of the valve  400 , i.e. the inner volume  202  of the casing  200 , when the valve  400  is open, and the inner volume  102  of the liner  100 . 
     In the final switched state shown in  FIG. 7 , the valve  500  provides a connection between the paths  504  and  506 . The connection between the output of the valve  400  and the inner volume  102  of the liner  100  is interrupted and a connection is established between the inner volume  102  of the liner  100  and the annular volume EA 1  of the well. 
     As will be described in more detail hereafter, the final state shown in  FIG. 7  is obtained after breaking of a disc  920  associated with the piston of the spool  500 . It will be observed that the pressure applied from the non-return valve  400  remains in the inner volume  102  of the liner  100  until breaking or degradation of the pin  590 . 
     As indicated previously, the valve  500  comprises a piston adapted to define in the final switched state a second valve  510  with a direction opposite that of the valve  400 , on the passage running from the inner volume  202  of the casing  200  to the inner volume  102  of the liner  100 . The equivalent schematic of the assembly  300  thus obtained in the final switched state is shown in  FIG. 8 . In this  FIG. 8  the valve  510  has been shown schematically comprising a body which defines a conical seat  512  tapered when approaching the input coming from the inner volume  202  of the casing  200 , a closure member  514  placed upstream of the seat  512  with respect to a fluid feeding direction running from the inner volume  202  of the casing  200  toward the inner volume  102  of the liner  100  and a spring  516  which biases the closure member  514  into sealed contact with the seat  512  and thereby which biases the valve  510  to closure. 
     The seat  512  and the closure member  514  are advantageously made of metal, defining a metal/metal valve  500  with sealing means. 
     In the initial state of the valve  500 , the valve  510  is open. During the switching of the valve  500  after breaking of the disc  920 , the valve  510  closes under the biasing from the spring  516 . The assembly then comprises two valves  400  and  510  with opposite directions, back to back, which prevent any circulation of fluid in any direction between the inner volume  202  of the casing  200  and the inner volume  102  of the liner  100 . 
     The three-way valve  500  can be subject to numerous modes of implementation. It preferably comprises a piston  550  equipped with and/or associated with a closure member  514  made of metal mounted with the ability to translate within a body  310  made of metal of the assembly. More precisely, the piston  550  is translatably mounted in a chamber  320  of the body  310  into which lead pipes corresponding to the paths  502 ,  504  and  506  and are connected respectively to the inner volume  202  of the casing  200 , to the inner volume  102  of the liner  100  and to the inner volume EA 1  of the well P. 
     In the remainder of the description of the concept, the term “body  310 ” must be understood without any limitation whatsoever, the body  310  comprising the whole of the housing which houses the functional elements of the three-way valve  500  and, if appropriate, of the input valve  400 , and possibly composed of several parts. 
     The chamber  320  and the piston  550  are stepped and the pipes  502  and  504  lead into locations distributed longitudinally in the inner chamber  320 . The pipe  506  is, for its part, located axially in the channel  340 , in the extension of the chamber  320 . 
     The valves  400  and  510  have been previously described, the seats  410 ,  512  whereof, and the closure member  420 ,  514  are advantageously made of metal, thus defining the valves  400 ,  510  as metal/metal with a seal  470 ,  570 . 
     The sealing means allow a reduction of any risk of loss of sealing between such a metal closure member and its associated metal seat. For example, these additional sealing means consist of an O-ring seal (or any equivalent means, for example an O-ring associated with a ring) adapted to rest on a complementary bearing when the valve is in its closing position or near its closing position. Thus the valve  400  and/or  510  is and remains sealed even if the closure member  420  or  514  is not resting perfectly against its associated seat  410  or  512 , for example in the event that the fluid conveyed is not correctly filtered. 
     Such an additional seal  470 ,  570  is provided by the closure member and is adapted to come into contact against a complementary bearing formed on the body housing the valve and forming the seat, when the valve is in its closing position or near its closing position. The seal can, as a variant, be provided on the body housing the valve and forming the seat, and then be adapted to come into contact with a complementary bearing formed on the closure member, when the valve is in its closing position or near its closing position. 
     In one embodiment, an additional seal  570  is mounted in a groove formed on the closure member  514 . This seal  570  is adapted to come into contact against a complementary bearing  511  formed at a cut-out on the body  310  housing the valve  510 , aligned with and upstream of the seat  512 . The diameter of the cut-out which forms the bearing  511  is, on the other hand, slightly smaller than the outer diameter at rest of the seal  570  to ensure the aforementioned sealing effect. 
     It will be noted that, preferably, the travel of the closure member  514  is such that in the initial position, the seal  570  is placed beyond the input pipe  316  so as not to perturb the flow of fluid providing for inflation of the liner  100 . In other words, the pipe  316  is located, in the initial position, between the seal  570  and the bearing  511 . 
     According to another advantageous feature of the present invention, the input valve  400  and the valve  500  are preferably formed in distinct parallel longitudinal channels formed in the body  310  of the assembly  300  parallel to the longitudinal axis of the casing  200 , the aforementioned longitudinal channels being connected by transverse pipes. 
     The embodiment illustrated in  FIGS. 9 to 12  which correspond to a first embodiment of an assembly  300  conforming to the present invention will now be described, comprising a device  500  forming a three-way valve held initially by releasable immobilization means  900  and comprising, in the switched state, two opposite valves back to back,  400  and  510 . 
     In the remainder of the description, the terms “upstream” and “downstream” will be used with reference to the direction of displacement of a fluid from the inner volume  202  of the casing  200  to the inner volume  102  of the liner  100 . 
     According to this first example, the assembly  300  comprises, in the body  310 , two mutually parallel longitudinal channels  330  and  340  parallel to the axis O-O of the casing  200 . The channels  330  and  340  are located in different radial planes. The channel  330  houses the input valve  400 . The channel  340  houses the three-way valve  500 . 
     The longitudinal channel  330  communicates with the inner volume  202  of the casing  200 , at a first axial end, through a radial channel  312  closed at its radially outward end by a stopper  314 . 
     In proximity to its second axial end which receives the non-return valve  400 , the longitudinal channel  330  communicates with the second longitudinal channel  340  through a transverse passage  380 . 
     The longitudinal channel  340  has a second transverse passage (pipe)  318  which communicates with the inner volume  102  of the liner and an opening  350  which leads axially outward to the annular volume EA 1  of the well. 
     In practice, communication with the annular space EA 1  is accomplished by a plurality of radial openings in the longitudinal channel  340  beyond the opening  350 . 
     The passage  380 , the passage  318  and the opening  350  form respectively the three paths  502 ,  504  and  506  of the valve  500 . 
     The first longitudinal channel  330  has a conical zone  410  which diverges going away from the first end connected to the input radial channel  312  and which forms the aforementioned seat of the valve  400 . This conical zone  410  is located upstream of the pipe  316 . 
     As can be seen in  FIG. 9 , the channel  330  houses, facing this seat  410 , a closure member  420  including a complementary conical end urged to press against the seat  410  by a spring  430 . 
     As described previously with respect to  FIGS. 6 to 8 , such a valve  400  is closed when at rest and opens when, the valve  500  allowing passage between the inner volume  202  of the casing  200  and the inner volume  102  of the liner  100 , the pressure exerted on the closure member  420  by the fluid present in the casing  200  exceeds the force of the spring  430 . 
     The second longitudinal channel  340  has a conical zone  512  located axially between pipe  316  and passage  318 . The zone  512  diverges when approaching the first pipe  316  and forms the aforementioned seat of the valve  510 . 
     As can be seen in  FIGS. 10 to 12 , the channel  340  houses a piston  550  and a closure member  514  capable of translation. 
     The closure member  514  is placed upstream of the piston  550  and rests on the upstream end  556  of the piston  550 . It has, facing the seat  512 , a conical zone complementing the seat  512 . The closure member  514  is urged to press against the seat  512  by a spring  516 . 
     The diameter of the piston  550  is less than the diameter of the smallest section of the zone  512  which forms the seat of the valve  510 , so that the fluid can freely invade the chamber  320 . All the annular space around the piston  550  bathes in the fluid, which means that the chamber  320  is at the fluid pressure. 
     It is thus noted that, in the initial position, the pressure in the chamber  320  is equal to the pressure in the liner  100 . 
     In other words, it is important that, in the initial state there is absolutely no sealing effect between pipe  316  and passage  318  and the end of the chamber  320  where the releasable immobilization means  900  are located, so that the fluid can penetrate all of said chamber  320 . 
     At rest, however, in the initial position, the conical closure member  514  is held away from the seat  512  by the piston  550  and the immobilization means  900  placed in the bottom of the channel  340  facing one end  552  of the piston  550  aligned axially with the piston downstream of the closure member  514 . The piston  550  is resting on said releasable immobilization means  900 . 
     The closure member  514  is mounted movable in translation and is therefore, in the initial state, in contact with the end  554  opposite to the end  552  of the piston  550 , which in turn is in contact with said immobilization means  900  in the initial position. 
     The immobilization means  900  take the form of a valve  910  inserted between the chamber  320  and the opening  350  in communication with the annular volume EA 1 . In the initial state, a breaking disc  920  prevents any fluid communication between the chamber  320  and the opening  350 . In other words, said immobilization means  900  close the connection between the chamber  320  and communication to the opening  350 . 
     In  FIGS. 10 to 13 , the assembly  300  comprises the housing  310  and a sub-part  319  wherein are comprised the immobilization means  900 . The housing  310  and the sub-part  319  can nevertheless consist of a single part. The division into two independent parts is convention for reasons of manufacture of the assembly. A seal  319   a  can be placed between the sub-part  319  and the housing  310  to prevent any leakage of fluid from the chamber  320  between the subpart  319  and the housing  310 . 
     As mentioned previously, the term body  310  will hereafter be employed as a generic term to designate a block or a block composed of several sub-parts. 
     Under the influence of the pressure of the fluid prevailing in the chamber  320 , the releasing means  900  can break and open, thus releasing the piston  550  in the process and consequently also releasing the closure member  514  which can now close the pipe  502 . In practice, it is necessary to take into account the pressure in the opening  350  toward to the annular space EA 1 , as well as the force exerted by the piston  550  on said means  900  due to the force exerted by the spring  516  on the closure member. 
     It is thus possible to define a threshold pressure difference ΔPs at which said means  900  break. Such a pressure difference ΔPs depends for example on the size of the breaking disc  920  and the effective surface area that it offers the fluid in the chamber  320 . Given the value of the pressure in the chamber  320 , it is possible to neglect the force due to the piston  550  which is pushed by the spring  516 . 
     In particular, the higher the effective surface area of the disc  920 , the more the forces connected with the thrust on the piston  550  from the spring  516  will be negligible. 
     After breaking under the joint effect of the pressure differential between the inner pressure of the liner  100  and the pressure of the annular volume EA 1  and the spring  560 , the immobilization means  900  are open, which opens the connection with the opening  350  and the piston  550  is no longer held in its initial position. Consequently, the spring  516  causes the piston  550  to undergo translation by means of the immobilization means  900  by means of the closure member  514 , and the latter can from now be pressed by said spring  516  against its seat  512 , thus closing the pipe  316 . 
     After releasing the means  900 , the piston  550  does not play any particular role and can, depending on the movements of the fluid, come back into contact with the closure member  514  or come into contact with the immobilization means  900  which have been broken (see  FIG. 12 ). 
     Whatever its position, said piston  550  does not isolate any portion of the chamber  320  from another, nor does it prevent any flow of fluid, because its diameter is less than the different cross-section diameters of the chamber  320 , comprising the seat  512 . 
     Inasmuch as the connection established in the final state between the passage  318  which communicates with the inner volume  102  of the liner and the opening  350  which communicates with the outer annular volume EA 1  serves to equalize pressure, the movements of fluid between these two volumes are small, and if they occur, the flow rate is low and/or slow. 
     The immobilization means  900 , and in particular the breaking disc  920 , thus have a dual function:
         The first is to hold in the initial position the piston  550  which in turn allows the closure member  514  to be held in the open position,   The second is to prevent, respectively allow, communication between the inner volume  102  of the liner  100  (via the chamber  320 ) and the outside in the annular volume EA 1  of the well (via the opening  350 ), in the initial state, respectively in the final state once a certain pressure is attained in the chamber  320 .
 
These two functions are interdependent, inasmuch as when the closure member  514  is held in the open position, communication toward the outside through the opening  350  is not allowed, and when the closure member  514  is no longer held in the open position, communication toward the outside through the opening  350  is allowed.
       

     In comparison to embodiments using breaking pins placed transversely, this technique allows better control and better precision in the breaking value, as well as greater reliability. In fact, it is essentially the pressure exerted by the fluid in the chamber  320  which causes the breaking of the breaking disc  920 . However, the forces induced by a fluid pressure are more easily calculated and predictable than the shearing forces in the pins, said forces being exerted by the displacement of the part wherein is inserted the breaking pin. 
     In addition, there exists a breaking disc industry which has extended knowledge of breaking prediction, unlike the pins which are generally of inner manufacture. 
     As mentioned previously, the greater the effective surface area of the breaking disc  920 , i.e. the greater the surface on which the pressure is able to exert an uncompensated force on the disc, the greater the reliability of the immobilization means  900  will be with respect to the piston  550  which exerts a force on the spring  516 . 
     The person skilled in the art will understand that according to all the embodiments conforming to the invention, the isolation system integrates a three-way valve  500  including a single switching piston  550  so that: 
     During a setting up phase of the annular isolation system in a well, the system is in communication with the inside of the casing  200  such that the pressures are balanced between the inside of the lining  100  and the inside of the casing  200 . On the other hand, there is not possible communication between the inner volume  102  of the liner  100  and the annular space EA 1  or EA 2  or between the casing  200  and the annular space EA 1  or EA 2 . 
     During an inflation phase, the inner volume  102  of the liner  100  is in communication with the inside of the casing  200 . Thus, when the pressure increases in the casing  200 , the pressure increases likewise in the liner  100 . On the other hand, there is no possible communication between the inner volume  102  of the liner  100  and the annular space EA 1  or between the casing  200  and the annular space EA 1 . 
     At the conclusion of inflation, the movement of the piston  550  is released by the breaking of the immobilization means  900  caused by the increase in the pressure differential which makes it possible to inflate the system. The breaking of the immobilization means  900  definitively releases the movement of the piston  550  and closes communication between the casing  200  and the inner volume  102  of the liner  100 , and opens at the same time communication between the inner volume  102  of the liner  100  and the annular volume EA 1 . After breaking of said means  900 , it is no longer possible to inflate the isolation system from the casing. 
     The valve  500  is constituted in such a fashion that the reverse movement of the piston  550  plays no part even if a pressure differential, positive or negative, exists between the annular space EA 1  and the inside of the casing  200 . 
     When a pressure differential is applied from EA 1  to EA 2  such that P EA1 &gt;P EA2 , the fluid, and hence the pressure, communicates inside the expandable liner  100  through passage  318  and opening  350  of the valve  500 . The inner pressure of the expandable membrane  100  is identical to the pressure in the annular zone EA 1 , which confers on it excellent zone isolation properties. 
     If the annular pressure varies over time and can be alternatively: pressure of EA 1 &gt;pressure of EA 2  or pressure of EA 2 &gt;pressure of EA 1 , mounting two zone isolation systems head-to-tail can be mounted as illustrated in  FIG. 13 . 
     Of course, the present invention is not limited to the embodiments which have just been described, but extends to any variant conforming to its spirit. 
     The valves  400  and  510  have been described previously the seat whereof  410 ,  512  and the closure member  420 ,  514  are advantageously made of metal thus defining metal/metal valves  400 ,  510 . 
     As indicated at the beginning of the description, the device  500  can be used within a larger scope. 
     In particular, in one embodiment the valve  500  is independent of the non-return valve  400  and consists of a three-way valve in which, in the initial state, a communication between the inside of the casing and the inside of the liner is allowed by immobilization means  900  which hold the closure member in the open position and, in the final state, communication toward the outside annular volume is allowed thanks to the opening of the opening  350  following the breaking of the immobilization means  900 . 
     The invention is not limited to a closure member  540  held in the closing position by the spring  560 . In fact, it is possible to provide, in an architecture other than that previously presented, that the closure member  540  is free in its translations depending on the pressures in the pipes, so that they can be alternately open or closed even when the immobilization means  900  are in the final position. 
       FIGS. 14 to 16  show a device without the spring  560 . 
       FIGS. 17 and 18  show a measurement system  1000  implemented in the device and intended to evaluate the position or the state of the device  500  (first position, initial state, second position, final state). This system can be implemented in all the embodiments. 
     The measuring system  1000  allows measurement of the longitudinal displacement of the piston  550  inside the chamber  320 . 
     To this end, said system  1000  comprises
         a magnet  1100  placed inside the piston  550 . Preferably and as shown in  FIGS. 17 and 18 , for positioning reasons, the magnet  1100  is located at the end  552 , i.e. the end which is in contact with the breaking means  900  in the initial state,   a sensor  1200 , placed in the housing  310  surrounding the piston  550  and configured to acquire the longitudinal position (or abscissa) of the magnet  1100 , and thus to know the longitudinal position of the piston  550 . In  FIGS. 17 and 18 , the sensor extends substantially along the breaking means  900  so as to be able to acquire the position of the magnet  1100  when the piston  550  passes through the breaking disc  920 .       

     In  FIG. 17 , the device  500  is in the initial state, i.e. the breaking means  900  have not broken. 
     In  FIG. 18 , the device  500  is in the final state, i.e. the breaking means  900  have broken. The sensor  1200  has thus detected a longitudinal displacement of the magnet  1100  indicating that the device is in the final state. 
     The measuring system  1000  thus makes it possible to know if the disc  920  has broken, and therefore if the connection between the inner volume  102  of the liner  100  and the annular space EA 1  outside the casing is allowed and therefore, particularly in the presence of the spring  516 , whether the closure member  514  is on its seat and closes the pipe  316  associated with the inside of the casing. 
     By way of an example, the displacement of the piston  550  is 15 mm between the two states. 
     The recovery of the sensor data is accomplished by means of a tool (called a “wireline”) held by a cable, which is lowered into the well (not shown in the figures). If necessary, the tool is associated with a tractor which allows displacement of the tool in the horizontal portions. 
     The cable has a mechanical role (for dropping and raising the tool) and an electronic one (for transmitting the data and controlling the tool/the tractor). 
     Transmission of data from the measuring system  1000  is accomplished wirelessly.