Method and apparatus for sealing an undesirable formation zone in the wall of a wellbore

Abstract

An apparatus for sealing a section of a wall of a wellbore adjoining a target zone containing undesirable fluids for preventing penetration of the undesirable fluids into the wellbore is described. The apparatus includes an inflatable balloon deployable in the wellbore, a coiled tubing for deploying the inflatable balloon into the wellbore and an inflating assembly tool for inflating the balloon to form a seal over the adjacent target zone of the well bore wall.

Claims

1. An apparatus for sealing a section of a wall of a wellbore adjoining a target zone containing undesirable fluids for preventing penetration of the undesirable fluids into the wellbore, the apparatus comprising: an inflatable balloon deployable in the wellbore, the balloon comprising a central section, and upper and lower sections located, respectively, on opposite ends of the central section, each section configured to inflate in response to receiving formation plugging fluid, wherein the central section comprises a plurality of weakened areas configured to rupture during inflation to discharge the formation plugging fluid; a coiled tubing for deploying the inflatable balloon into the wellbore; and an inflating assembly tool for inflating the balloon to form a seal over the adjacent target zone of the well bore wall.

2. An apparatus for sealing a section of a wall of a wellbore adjoining a target zone containing undesirable fluids for preventing penetration of the undesirable fluids into the wellbore, the apparatus comprising: an inflatable balloon deployable in the wellbore, the balloon comprising a central section, and upper and lower sections located, respectively, on opposite ends of the central section; a coiled tubing for deploying the inflatable balloon into the wellbore; and an inflating assembly tool for inflating the balloon to form a seal over the adjacent target zone of the well bore wall, wherein the assembly tool comprises an inflating container filled with a formation plugging fluid and having at least three pressure-operated inflating valves for passing pressurized plugging fluid into the respective sections of the balloon.

3. An apparatus according to claim 2, wherein the central section of the balloon has a plurality of weakened areas configured to rupture during inflation to discharge plugging fluid.

4. An apparatus according to claim 2, wherein the downhole end of the coiled tubing is secured in fluid communication to a timed circulation valve, the timed circulation valve being programmed to be open for a predetermined time to circulate wellbore fluid into the coiled tubing while the balloon is lowered to a predetermined target zone, the timed circulation valve being set to close at a predetermined time required for pumping a fluid reactant via the coiled tubing from the surface to the circulation valve depth.

5. An apparatus according to claim 4, wherein an outlet of the circulation valve is in fluid communication with a chemical container containing a chemical reactant that produces an exothermic reaction upon addition of the fluid reactant, the chemical container in fluid communication with the timed circulation valve via a pressure-operated inlet valve programmed to open at a predetermined pressure to allow the fluid reactant to enter the chemical container, whereby a controlled explosive reaction occurs, the chemical container having a pressure-operated exit valve set to open under the pressure generated by the chemical reaction to admit reaction products into the inflating container, the inflating valves opening at a predetermined pressure in the inflating container to admit formation plugging fluid to inflate the sections of the balloon.

6. An apparatus according to claim 2, in which the inflating valves for the upper and lower sections are configured to provide a greater flow rate of the plugging fluid into the upper and lower balloon sections than the flow rate of plugging fluid into the central section, whereby the upper and lower sections are inflated more rapidly than the central section to provide fluid-tight seals against the wall of the well bore at opposite ends of the central section.

7. An apparatus according to claim 2, wherein upper and lower inflatable packers are secured and positioned above and below the inflatable balloon in axial alignment with the coiled tubing.

8. An apparatus according to claim 7, wherein each of the inflatable packers includes an electric pump in fluid communication with fluid in the wellbore.

9. An apparatus according to claim 7, wherein the inflatable assembly tool comprises an inflating container filled with a formation plugging fluid and at least one pressure-operated inflating valve for passing pressurized plugging fluid into the inflatable balloon.

10. An apparatus according to claim 9, wherein the balloon has a plurality of weakened areas configured to rupture during inflation to discharge plugging fluid.

11. An apparatus according to claim 9, which includes a timed circulation valve positioned below the upper inflatable packer in fluid communication with the coiled tubing, the timed circulation valve being programmed to be open for a predetermined time to circulate wellbore fluid into the coiled tubing while the balloon is lowered to a predetermined target zone, the timed circulation valve being set to close at a predetermined time required for pumping a fluid reactant via the coiled tubing from the surface to the circulation valve depth.

12. An apparatus according to claim 11, wherein an outlet of the circulation valve is in fluid communication with a chemical container containing a chemical reactant that produces an exothermic reaction upon addition of the fluid reactant, the chemical container in fluid communication with the timed circulation valve via a pressure-operated inlet valve programmed to open at a predetermined pressure to allow the fluid reactant to enter the chemical container, whereby a controlled explosive reaction occurs, the chemical container having a pressure-operated exit valve set to open under the pressure generated by the chemical reaction to admit reaction products into the inflating container, the inflating valve opening at a predetermine pressure in the inflating container to admit formation plugging fluid to inflate the balloon.

13. A method of sealing a section of a wall of a well bore adjoining a target zone containing undesirable fluids for preventing penetration of the undesirable fluids into the well bore, the method comprising the steps of: deploying an inflatable balloon in the wellbore using a coiled tubing; initiating an exothermic reaction to form reaction products; flowing the reaction products into the balloon; inflating, by the reaction products, the balloon to expand against and form a seal with the wall of the target zone; and contacting the reaction products with the interior of the inflated balloon to melt and separate the portion of the balloon in contact with the wall of the wellbore.

14. A method according to claim 13, wherein the inflatable balloon is deployed with a timed circulation valve which is programmed to keep the timed circulation valve open for a predetermined time necessary to circulate wellbore out of the well bore while the balloon is lowered to the predetermined target zone, introducing a fluid reactant into the coiled tubing and pumping said fluid reactant until it reaches the timed circulation valve, closing the timed circulation valve at the end of a predetermined time period required to pump the fluid reactant to the depth of the timed circulation valve, increasing pressure of the fluid reactant in the coiled tubing to a level sufficient to open a pressure-operated inlet valve that is located downstream of the timed circulation valve.

15. A method according to claim 14, comprising the steps of providing a chemical container containing a chemical reactant that produces an exothermic chemical reaction upon addition of a fluid reactant, introducing the fluid reactant into the chemical container to produce an exothermic controlled explosive reaction, and passing pressurized reaction products at a predetermined pressure into the inflating container, thereby displacing the formation plugging fluid and inflating the sections of the balloon.

16. A method according to claim 15, wherein the heat from the exothermic reaction softens and melts the portion of the central balloon that is in contact with the well bore wall and causes its separation from the remaining portions of the central balloon extending to their ends which remain secured to the inflating container.

17. A method according to claim 16 which includes increasing the internal pressure on the fluid in the inflating container from the surface via the coiled tubing to rupture the upper and lower balloons whereby the containers and the balloon remnants can be withdrawn through the production tubing.

18. A method according to claim 14, which includes positioning upper and lower inflatable packers above and below the balloon, inflating the inflatable packers with well bore fluids by activating electrical pumps associated with each of the packers, and forming fluid-tight seals with the wall of the well bore prior to inflating the balloon.

19. A method according to claim 18, wherein the step of inflating the balloon comprises providing an inflating container filled with a formation plugging fluid and having at least one inflating valve in fluid communication with the balloon and securely disposing the balloon around the inflating container for joint deployment of the balloon and inflating container.

20. A method according to claim 19, comprising the step of forming at least one weakened area in the balloon rupturing the at least one weakened area upon inflation of the balloon with formation plugging fluid, the upper and lower inflatable packers forming fluid-tight seals with the wall of the wellbore adjacent the balloon.

21. The method according to claim 20, wherein the formation plugging fluid passes through the rupture in the at least one weakened area of the balloon and is forced into the formation between the seals formed by the upper and lower inflatable packers as the balloon expands to the wall.

22. A method according to claim 19, comprising the steps of providing a chemical container containing a chemical reactant that produces an exothermic chemical reaction upon addition of a fluid reactant, introducing the fluid reactant into the chemical container to produce an exothermic controlled explosive reaction, and passing pressurized reaction products at a predetermined pressure into the inflating container, thereby displacing the formation plugging fluid and inflating the balloon.

23. A method according to claim 22, wherein the heat from the exothermic reaction softens and melts the portion of the balloon that is in contact with the well bore wall and causes its separation from the remaining portions of the balloon extending to their ends which remain secured to the inflating container.

24. A method according to claim 23, which includes deflating each of the expanded packers after the melted portion of the balloon has been separated from the inflating container by activating each of the electric pumps associated with the packers, and withdrawing the containers, deflated packers, and balloon remnants from the wellbore via the coiled tubing.

25. A method according to claim 13, wherein the balloon has a central section, and upper and lower sections located, respectively, on opposite ends of the central section and wherein the inflating step comprises providing an inflating container filled with a formation plugging fluid and having three inflating valves in fluid communication with the respective sections of the balloon for inflating them, and securely disposing the balloon around the inflating container for joint deployment of the balloon and inflating container.

26. A method according to claim 25, comprising the step of forming at least one weakened area in the central section, rupturing the at least one weakened upon inflation of the balloon with formation plugging fluid, the upper and lower sections forming fluid-tight seals with the wall of the wellbore adjacent the central section.

27. A method according to claim 25, wherein the inflating step comprises inflating the upper and lower sections more rapidly than the central section, whereby fluid-tight seals are provided against the wall of the well bore at the opposite ends of the central section.

28. A method according to claim 27, wherein the plugging fluid is forced into the formation between the seals formed by the upper and lower sections as the central balloon expands to the wall.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Preferred embodiments of the invention are described in more detail below and with reference to the drawings in which:

(2) FIG. 1 is an elevation view, partially in cross-section, of an apparatus constructed according to the present invention, the chemical balloon having three inflatable sections being deployed in an open-hole section of wellbore supported by coiled tubing and positioned below the end of the production tubing, the wellbore having an undesirable water zone and being filled with formation fluid or other completion fluid denoted herein as wellbore fluid;

(3) FIG. 2A is an enlarged partial cross-sectional view of an upper portion of the apparatus of FIG. 1, illustrating the displacement of wellbore fluid through the circulation valve once the apparatus has been lowered to the target zone;

(4) FIG. 2B is an enlarged partial cross-sectional view of the components of the apparatus of FIG. 1, illustrating the mechanism used for initiating the chemical reaction which expands the central balloon;

(5) FIG. 3 is an enlarged side elevation view of the multi-section chemical balloon which forms part of the apparatus of FIG. 1 and delivers formation plugging fluid to the target zone;

(6) FIG. 4 is an enlarged fragmentary view of a section of the central balloon shown in FIGS. 1 and 3, illustrating one of several weakened sections of the balloon that permit wall formation plugging fluid material to pass from the inflating container and through the weakened sections of the central balloon to penetrate the formation and seal the target zone while the balloon is inflating;

(7) FIG. 5 is a cross-sectional view, taken along lines 5-5 of FIG. 4, showing a portion of the weakened central balloon wall having a reduced thickness;

(8) FIG. 6 is a partial cross-sectional view of a portion of the central balloon wall shown in FIGS. 4 and 5, when ruptured during inflation allowing the pressurized formation plugging material reaction products to pass through the balloon wall into the annulus to seal the target zone;

(9) FIG. 7 is a cross-sectional view, taken along lines 7-7 of FIG. 3, illustrating an embodiment of the invention in which two or more expandable ratchet rings are embedded in the central balloon to provide circumferential rigidity to selected portions of the balloon as it expands during the chemical reaction and to maintain it in the fully expanded position against the wellbore wall following expansion;

(10) FIG. 8 is an enlarged view of the indicated portion of FIG. 7 illustrating the engagement of the ratchet rings;

(11) FIG. 9 is a cross-sectional view, taken along lines 9-9 of FIG. 7, of one embodiment of a rigid reinforcing band in the form of a diamond-shaped mesh metal strip embedded in the central balloon material to provide rigidity in the longitudinal direction to complement the circumferential rigidity provided by the expandable ratchet rings shown in FIGS. 3 and 7;

(12) FIG. 10 is an enlarged elevation view of a timed circulation valve secured in fluid communication via a pressure-operated valve to the chemical container filled with a reactant material;

(13) FIG. 11 is a cross-sectional view of the chemical container shown in FIGS. 2 and 10 in the process of initiating the reaction prior to discharging the pressurized reaction products via the lower pressure valve to inflate the balloons;

(14) FIG. 12 is a cross-sectional view similar to FIG. 11 showing the lower pressure-operated valve advanced to the open position to permit entry of the reaction products from the chemical container to the inflating container to thereby displace the formation plugging material while separately inflating the three chemical balloons;

(15) FIG. 13 is a cross-sectional view similar to FIGS. 11 and 12, illustrating the inflating of the three balloons at an intermediate stage with the upper and lower barrier balloons fully inflated in sealing contact with the wellbore wall to form a compartment with the central balloon partially inflated;

(16) FIG. 14 is a cross-sectional view similar to FIG. 13 illustrating the sequential entry of the reacting chemicals and displacement of the formation plugging fluid into the central balloon via the inflating valves located in the sides of the inflating container that supports the balloons, to expand the upper and lower balloons, and permit the plugging fluid to pass through the ruptured weakened portions of the central balloon and penetrate the formation after which the hot reaction product softens and melts the balloon while it is against the wall of the well to seal off the target water zone;

(17) FIG. 15 is a cross-sectional view, taken along lines 15-15 of FIG. 14, illustrating the expanded and separated melted portion of the central balloon and the corresponding expansion of the toothed ratchet ring outwardly to a position which stabilizes and maintains the expanded diameter of the separated portion of the central balloon, with the diamond mesh providing stability in the longitudinal direction;

(18) FIG. 16 is a cross-sectional view similar to FIG. 14 showing the completion of the wall sealing process and the partial withdrawal into the production tubing of the coiled tubing, the inflating container, the chemical container, and the residual material of the upper and lower balloons following their rupture.

(19) FIG. 17 is an elevation view, partly in cross-section of another embodiment illustrating the inclusion of an expandable wire stent device in the un-inflated balloon which will maintain the fully expanded central balloon against the wall of the wellbore.

(20) FIG. 18 is a cross-sectional view, taken along lines 18-18 of FIG. 17, showing the expandable wire stent device positioned between two extensible webs of a polymeric material that are embedded in the wall of the central balloon;

(21) FIG. 19 is a view similar to FIG. 17 illustrating the full expansion of the central balloon and the expanded wire stent device against the formation wall.

(22) FIG. 20 is an elevation view, partly in cross-section, of another embodiment which includes dual inflatable packers in place of the upper and lower balloons, illustrating the lowering of the apparatus into position in the target zone;

(23) FIG. 21 is an elevation view, partly in cross-section, similar to FIG. 20, illustrating the apparatus in position so that the central balloon is aligned with the target zone;

(24) FIG. 22 is an elevation view, partly in cross-section, similar to FIG. 21, illustrating inflation of the upper and lower inflatable packers by their respective electric pumps; and

(25) FIG. 23 is an elevation view, partly in cross-section, similar to FIG. 22, illustrating the passage of plugging fluid through the ruptured weakened portions of the inflated central balloon to penetrate the formation in the target zone.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(26) Referring now to the drawings, and specifically to FIG. 1, there is shown in elevation and partially in cross-section, an apparatus 10 constructed according to one embodiment of the present invention. The apparatus includes a resilient inflatable component, referred to generally as balloon 12, which is comprised of a plurality of sections and, as illustrated, of three sections, there being a central section 12a, referred to as the main or middle, or central balloon, an upper balloon 12b, and a lower balloon 12c. In the description which follows, reference to balloon 12 contemplates the balloon in its entirety, including the three sections, 12a, 12b and 12c, where balloon 12a is the central or middle balloon. The three sections are inflated according to a predetermined sequence as will be described in greater detail below.

(27) The un-inflated balloon 12 and related components described below are deployed in the wellbore 11 by coiled tubing 14 which passes through production tube 30 until it reaches target zone 16 of the wellbore. For purposes of describing this embodiment, target zone 16 will be denoted as an undesirable water zone. In FIG. 1, undesirable target zone 16 is located deeper in the wellbore 11 than the lowermost end 22 of production tubing 30 and well casing 18.

(28) The undesirable zone 16 may also represent a lateral drill hole which may be horizontal or angled, and which may have been partially damaged by one or more of a number of factors, including, but not limited to, contact with wellbore fluids used during drilling/completion and workover operations. It is a zone of reduced permeability within the vicinity of the wellbore 11 (i.e., skin), often the result of foreign fluid invasion into the reservoir rock.

(29) The three balloons 12a, 12b and 12c can be made of any suitable flexible thermoplastic expandable material, i.e., a polymer, and preferably rubber, natural or synthetic. Different flexible and resilient materials can be used for each of the three balloons and/or the individual balloons can be produced with different wall thicknesses, physical properties and means for attachment to their supporting surface. The thickness and resiliency of the walls, or sections of the walls of the respective balloons is sufficient to permit the expansion and secure contact with the adjacent wall surface.

(30) As will be described in greater detail below, the balloons 12 are inflated via an exothermic reaction in the chemical container 34 which is initiated by the pumping of a predetermined volume of a fluid reactant 33 (not shown) from the surface via the coiled tubing 14 and through the upper pressure-operated inlet valve 36 into the chemical container 34 and into contact with one or more reactant material(s) loaded in the chemical container 34 during preparation of the apparatus before it is lowered into the wellbore 11. The inflating container 24 is also filled at the surface with formation plugging fluid 25 and has at least three inflating ports. In the preferred embodiment, the three balloons are secured in position on the outside surface of the inflating container 24, e.g., by an adhesive. The central balloon preferably has a plurality of weakened areas that will rupture at the early stages of inflation. After rupturing, the weakened wall will allow the passage of the formation plugging fluid from the inflating container 24 while allowing the balloon 12 to inflate and expand radially into the annular space or compartment defined by the adjacent balloons.

(31) The upper and lower balloons 12b and 12c will inflate first to provide tight seals against the wall of the well at either end of the central balloon, thereby acting as barriers to the plugging fluid 25. This fluid-tight compartment will permit the formation plugging fluid 25 to be forced deep into the formation under the pressure produced by the hot rapidly expanding reaction product. As noted, initially, the wellbore 11 is filled with formation fluids or other completion fluids which are referred to herein as wellbore fluid.

(32) Referring now to FIGS. 2A and 2B in conjunction with FIG. 1, the balloon 12 is positioned and supported by inflating container 24, which includes a plurality of inflating valves 26, 27 and 28, which, when open, permit passage of the formation plugging fluid 25 under pressure, and expand the three sections 12a, 12b and 12c of balloon 12 when the reaction products from above enter the container 24 is described in greater detail in the discussion of FIGS. 11-14.

(33) Referring again to FIGS. 2A and 2B in conjunction with FIG. 1, the assembly of the invention includes coiled tubing 14 deployed via production tubing 30 into the borehole which is attached at its lower end to timed circulation valve 32 which in turn, is attached to chemical container 34, which is secured in fluid communication via pressure valve 40 to inflating container 24. The circulation valve can be any type of programmable circulation valve which is manufactured for oil drilling applications, such as the Halliburton eRED-HS Remotely Operated Circulating Valve or the Omega Remote Completion Circulating valve. The timed circulation valve 32 is kept open while the tool is lowered into the borehole so that wellbore fluids enter the coiled tubing, thereby facilitating deployment of the assembly through production tubing 30.

(34) The chemical container 34 can contain any suitable chemical reactant(s) 38 that can be activated to produce an exothermic reaction and preferably provide a limited or controlled explosive expansion by the addition of a fluid reactant as an activating medium. In the present example, the chemical container 34 preferably houses a supply of pure solid reactant material, such as sodium metal 38, which can later be activated by an appropriate amount of water delivered via the coiled tubing from the surface under pressure to initiate the necessary reaction with sufficient force to rapidly expand the rubber balloons 12. For safe handling, the sodium metal can be submerged in kerosene or other non-reactive liquid in the sealed chemical container 34. Other appropriate known reactant materials are contemplated as within the scope of the invention, provided that they are capable of producing a rapid exothermic reaction.

(35) Once the balloon 12 reaches the target zone 16, a predetermined volume of activating fluid reactant 33 that is required to complete the highly exothermic reaction with the chemical(s) inside the chemical container 34 is pumped into the coiled tubing 14 from the surface. The fluid reactant is followed by a displacing liquid (not shown) which is pumped into the coiled tubing 14 to displace wellbore fluids 31 through the timed circulation valve 32 as is illustrated in FIG. 2A. The timed circulation valve 32 is programmed so that the circulation valve timer (not shown) accounts for the time required for the activating fluid reactant 33 to be pumped from the surface to the circulation valve depth. When the fluid reactant 33 reaches the timed circulation valve 32, pumping may be stopped while the timed circulation valve 32 automatically closes, after which, additional displacing fluid is pumped into the coiled tubing to raise the pressure to a sufficient level to open pressure-operated inlet valve 36 which is positioned on chemical container 34. Alternatively, the flow of fluids may be continuous and the circulation valve will automatically change the flow pattern to permit the fluid reactant to develop sufficient pressure to open valve 36.

(36) Referring again to FIG. 2B, the pressure-operated inlet valve 36 is set to open at a predetermined pressure, thereby allowing the activating fluid reactant 33 (e.g., water) to enter the chemical container 34 and react with the reactant chemical, e.g., sodium 38, initiating the controlled explosive reaction within chemical container 34.

(37) Pressure-operated exit valve 40 is positioned at the bottom of the chemical container 34 and communicates with the inflating container 24. The pressure-operated exit valve is set to open under the pressure generated by the chemical reaction and permit the hot pressurized reaction products to enter the inflating container 24.

(38) Upon entry of the reaction products into inflating container 24, the three pressure-operated inflating valves 26, 27, and 28 open to permit the formation plugging liquid 25 to exit the inflating container and begin inflating the three sections of the balloon 12 according to the predetermined sequence described above. The central balloon 12a inflates at a lower rate because of its relatively greater volume, while the adjacent smaller balloons 12b and 12c will be fully inflated first and provide the required seals with the wellbore wall to isolate the target zone 16. This filling sequence can also be achieved by varying the size or flow rate of the plugging fluid through the valves to the respective balloons 12b and 12c, and/or by lowering the pressure setting at which the valves 26 and 27 open. With reference to FIG. 3, the formation plugging fluid begins to pass through the weakened sections 47 in the central balloon 12a as the pressure and volume inside increases. As will be described in greater detail below, the expandable ratchet rings 44 also expand to provide circumferential support following the completed inflation of the central balloon 12a against the wall.

(39) The functioning of the weakened sections 47 in the central balloon 12a is illustrated in FIGS. 4-6. FIG. 4 is an enlarged view of weakened section 47 of the central balloon 12a. As shown in FIG. 5, a cross-sectional view taken along lines 5-5 of FIG. 4, the balloon wall is of a reduced thickness. As shown in FIG. 6, the rupturing of the weakened section 47 of the balloon wall allows formation plugging fluid to escape through the balloon wall 12a in order to seal the target zone.

(40) Again referring to FIG. 2B, in a further preferred embodiment, inflating valves 26, 27 and 28 can be of different sizes and/or permit different flow rates in order to more rapidly inflate balloons 12b and 12c. The inflating valves 26, 27 and 28 are opened by controlled explosive force of the chemical reaction, and permit the reaction products to displace the plugging fluid and the balloons 12b, 12c and 12a to displace the formation plugging liquid in the inflating container 24, and to inflate to their positions in contact with the wall of the wellbore 11 as best shown in FIG. 13. Upper and lower balloons 12b, 12c are end balloons which inflate faster than central balloon 12a and provide stability to the entire installation while sealing the upper and lower spaces between the inflating container 24 and the wellbore 11. Although pressure-operated inflating valves 26, 27 can open at the same time as pressure-operated valve 28, expansion of central balloon 12a is not to be as rapid as upper and lower balloons 12b and 12c.

(41) It should be noted that alternative valve arrangements, such as pre-programmed RFID tags operated by radio frequency and pumped tags provided from the surface with prior art electronically actuated valves such as Omega valves, can also be incorporated into the present invention by one of ordinary skill in the art. However, the pressure-operated valves as described above, are presently preferred. The pressure operated valve is a conventional injection-pressure-operated valve such as those manufactured by Schlumberger and Halliburton.

(42) As noted above, the openings 47 in the sidewall of the body of the central balloon 12a will allow the passage of the pressurized formation plugging fluid from the inflating container 24 into the annulus between expanding balloon 12a and the wellbore wall, while also causing the balloon to inflate at a slower rate than the upper and lower balloons, 12b and 12c.

(43) The formation plugging fluid 25 is initially in the inflating container 24. As shown in FIG. 14, the formation plugging fluid 25 is displaced to the inflating container through inflation valves 26, 27 and 28 by the force or pressure produced by chemical reactants 29 coming from the chemical container 34 above it and with which it is in fluid communication. As it is displaced, the formation plugging fluid 25 and the chemical reactants 29 inflate the balloons 12a, 12b and 12c, and enter the annulus through the one or more openings 47 in the central balloon. The formation plugging 25 fluid can be of any suitable known type that is consistent with and functions to seal the particular formation well under the prevailing conditions. The wellbore fluid originally in the annulus 19 will be displaced into the pores and fissures of the adjacent reservoir rock by the formation plugging fluid 25 as it enters the annulus 19 from the openings 47 in the central balloon 12a.

(44) As shown in FIG. 16, after inflation of the central balloon 12a, and forcing the formation plugging fluid 25 into the formation wall, the hot reaction products 29 will cause the central balloon 12a to burst at its upper and lower periphery, soften and melt against the wall of the wellbore 11. A large portion of the central balloon 120a will be melted and in full contact with the wall of the well after its maximum inflation. The longitudinal portion of the central balloon is thus separated from attachment to the exterior of the inflating container.

(45) With reference to FIG. 14, the structure of the upper and lower balloons 12b, 12c are stronger than the structure of the central balloon 12a due to the plurality of weakened sections 47 which are ruptured when the reaction takes place. The weakened sections 47 in the central balloon 12a will also permit the wall plugging fluid to pass through the ruptured portions and penetrate the wall behind the elastomeric polymer material of the central balloon 12a.

(46) Referring to the stage illustrated in FIG. 15, as the central balloon 12a expands, it pushes the original wellbore fluid and the formation plugging fluid that was inside the inflating container 24 deep into the formation.

(47) At this stage of the process, the body of the central balloon 12a is fully exposed to the heat generated in the exothermic chemical reaction from chemical container 34 directly above it. As noted, the heat of the reaction product melts the central balloon 12a against the wall of the well, and at the same time, it will be retained in position by the expandable ratchet rings 44 and supported longitudinally by the rigid bands or straps 42.

(48) The upper and lower balloons 12b, 12c are not affected by the exothermic reaction because they are initially fully inflated by the formation plugging fluid and there is no aperture in either of these annulus-sealing balloons through which the plugging fluid can escape.

(49) Again referring to FIG. 16, after the completion of the wall sealing or plastering step, pressurized fluid is pumped from the surface through the coiled tubing to rupture the upper and lower balloons 120b (not shown), 120c to enable the apparatus to be retrieved through the production tubing 30.

(50) After the parting of the central balloon 120a and the bursting of the upper and lower balloons 120b, 120c, the coiled tubing can be withdrawn from the wellbore 11 with the remnants of the central, upper and lower balloons 120b, 120c, leaving the principal portion of central balloon 120a in position to seal the undesirable water zone of the wellbore 11.

(51) Referring to FIGS. 7-9, at least the central balloon is preferably strengthened both circumferentially and longitudinal by the addition of reinforcing components. For longitudinal rigidity, a plurality, e.g., four or more rigid reinforcing bands or straps 42, e.g., of metal diamond mesh, are embedded in the polymeric material in spaced-apart relation about the periphery as shown in FIGS. 7-9.

(52) For circumferential strength, an expandable ratchet ring 44 is positioned within opened-ended tube 45 which is embedded in, or bonded to the interior surface of the circumference of the central balloon 12c. It is preferable to position ratchet right ring at either end of the central balloon to hold it firmly in position when expanded against the wall above and below the target zone. One or more additional transverse ratchet rings can be provided based on the longitudinal length of the target zone that must be covered by central balloon 12c.

(53) The expandable ratchet ring 44 is comprised of two metal rings 44a, 44b, having overlapping teeth on the inner facing sides as best shown in FIG. 8. The teeth are generally uniform, but asymmetric, with each tooth having a moderate angular slope 46 on one side, and a steeper slope 48 on the other side. The moderate angular slope 46 on one side allows the overlapping teeth to slide over each other during expansion of the balloon 12, and the steeper slope 48 prevents the ring 44 from collapsing after expansion of balloon 12, and retains the supporting ring 44 in the expanded configuration. As noted, and as best shown in FIG. 8, the ratchet ring 44 is contained inside an open-ended flexible circular tube 45, the ends of the opening 50 initially facing each other. The flexible tube 45 constrains the ratchet ring 44 and keeps the teeth of the ratchet ring 44 in engagement at all times after expansion of the central balloon 12a. The opening 50 of the tube 45 allows the expansion of the ring inside the tube, as the two facing ends of the tube opening move away from each other.

(54) Referring to FIGS. 17-19, in another embodiment of the invention an expandable wire stent device 70 is utilized to maintain the fully expanded central balloon against the wall of the wellbore. FIG. 17 illustrates the embodiment utilizing the expandable wire stent device 70, prior to initiation of the chemical reaction described above, where central balloon 12a and expandable stent device 70 have not yet been expanded by passage of formation plugging fluids from the inflating container 24 into the central balloon 12a through pressured-operated inflation valve 28.

(55) As shown in the enlarged cross-sectional video of FIG. 18, the expandable wire stent 70 is positioned between two webs 72a, 72b and embedded in the walls of the central balloon 12a. Similarly to the embodiment illustrated in FIGS. 7-9, additional longitudinal support may be provided by rigid reinforcing bands or straps 42 which are also embedded in the walls of the central balloon 12a.

(56) With reference to FIG. 19, upon initiation of the chemical reaction as discussed above with reference to FIG. 2B, the formation plugging fluid 25 is forced through pressure-operated inflation valves 26, 27, 28, thereby expanding the balloons 12a, 12b, 12c. As the central balloon 12a expands so does the extendable wire stent device 70 and the webs 72a and 72b. The webs 72a and 72b are fabricated from an extensible material that will stretch as the balloon and the wire stent expands. Polymers and copolymers of vinyl, polyethylene and polypropylene can be used. When the pressure in the central balloon 12a reaches a sufficient level, formation plugging fluids 25 pass through the ruptured weakened portions 47 of the central balloon, after which they penetrate the formation in the target zone 16. As in the embodiment described in FIG. 15, once the central balloon 12a and expandable stent device 70 are fully expanded against the wall surface, the heat of the reaction product softens and melts the central balloon 12a against the wall of the well, and is maintained in position by the expandable wire stent 70 and supported longitudinally by the rigid bands or straps 42 shown in FIG. 18.

(57) Referring to FIGS. 20-23, in an alternative embodiment of the invention, the upper and lower balloons used to isolate target zone 16 are replaced by a dual inflatable packer system which includes an upper inflatable packer 80a and a lower inflatable packer 80b, each of which are inflated with wellbore fluid 31 by separate electric pumps 82a and 82b. The packers are constructed of a reinforced rubber composition for durability during repeated usage of the assembly. Electrical wiring (not shown) extends from each of the packers to the wellhead where controls for the pumps are provided. Inflatable packers are well known in the art and can be adapted by one of ordinary skill for use in this configuration of the present invention.

(58) FIG. 20 illustrates the lowering of the assembly utilizing the dual inflatable packer system through the production tubing 30 via the coiled tubing (not shown). The apparatus is lowered until the inflating container 24 and central balloon 12a are aligned with the target zone 16. As explained with respect to FIGS. 2A and 2B, the circulation valve 32 (not shown) is kept open while the tool is lowered into the borehole so that wellbore fluids enter the coiled tubing, thereby facilitating deployment of the assembly through the production tubing 30.

(59) With reference to FIG. 21, the upper inflatable packer 80a and its electric pump 82a are positioned above the circulation valve 32. The lower inflatable packer 80b and its associated electric pump 82b are positioned below the inflating container 24.

(60) FIG. 22 illustrates the inflation of the upper and lower inflatable packers 80a and 80b via electric pumps 82a, 82b which draw wellbore fluid 31 from the wellbore and discharge it under pressure into the inflatable packers 80a, 80b. When inflated, the upper and lower packers 80a, 80b expand into secure contact with the wellbore wall surface to maintain the assembly in a fixed position and to isolate the target zone 16 from wellbore fluids above and below the assembly.

(61) With reference to FIG. 23, once the upper and lower inflatable packers 80a, 80b have been inflated, the inflation of the central balloon 12a is initiated in the same manner as described above with respect to FIG. 2B. The central balloon 12a is inflated by the reaction products (not shown) which force the formation plugging fluids 25 out of the inflating container and into the balloon so that the weakened sections 47 of the central balloon 12a rupture, allowing the formation plugging fluids 25 to flow through the ruptured weakened sections 47 and penetrate the formation in the target zone 16. The inflated central balloon 12a continues to expand and is softened and is melted by the heat of the reaction in the same manner that was described above with respect to FIG. 15 so that inflated central balloon 12a, which is in contact with the walls of the target zone 16, melts against the wall of the well, thereby sealing the target zone 16. In this embodiment, the central balloon 12a is supported against the wall of the well by one or more of the above-described structural elements such as the straps or bands of rigid high tensile material 42, the expandable ratchet ring 44, and the expandable metal stent 70. The remnants of the central balloon are separated along the circumferentially weakened lines.

(62) After the target zone 16 has been sealed, the upper and lower inflatable packers 80a, 80b are deflated by the electric pumps 82a, 82b, which withdraw the wellbore fluid 31 from their respective packers and return it to the wellbore. Once the upper and lower packers 80a, 80b are sufficiently deflated, the apparatus is removed from the wellbore through the production tubing 30 via the coiled tubing 14.

(63) The sequence of process steps can be summarized in conjunction with reference the drawings as follows:

(64) FIG. 1 shows the apparatus in the initial state of its downhole deployment adjacent to the target zone 16 in the wellbore 11.

(65) FIGS. 2A and 2B show the function of the timed circulation valve 32 which is kept open to facilitate deployment of the apparatus 10, while the tool is lowered into the borehole so that wellbore fluids 31 enter the coiled tubing 14. Once the balloon 12 reaches the target zone, the activating fluid reactant 33 pressurized by the displacing liquid (not shown) are pumped from the surface into the coiled tubing 14 to displace the wellbore fluids 31 through the timed circulation valve 32. Once the activating fluid reactant 33 reaches the circulation valve 32 depth and the wellbore fluids 31 have been displaced, the circulation valve 32 automatically closes. Additional displacing fluid is pumped into the coiled tubing 14 from the surface in order to increase the pressure to a sufficient level to open the pre-set pressure-operated upper inlet valve 36. As shown in FIG. 10, when valve 36 opens, the activating fluid reactant 33 enters the chemical container 34 to produce the reaction with the chemical(s) 38.

(66) As shown in FIG. 11, the fluid reactant 33 enters the chemical container 34 via upper pressure-operated inlet valve 36 to initiate the reaction. The pressure of the reaction causes pressure-operated exit valve 40 to open, allowing the reaction products 29 to enter the inflating container tool 24.

(67) In FIG. 12, the hot reaction products 29 from the chemical container 34 enter the inflating container tool 24 through the lower pressure-operated valve 40 displacing the plugging fluid 25 into the balloons 12. The reaction products 29 pass through the pressure-operated inflation valves 26, 27 and 28 and the sequential full expansion of the balloon sections 12b, 12c and then 12a occurs as described in detail above in the discussion of FIGS. 13 and 14. Initially, upper balloon 12b and lower balloon 12c expand until they reach the wall surface and seal the adjoining annulus, while stabilizing the entire device during completion of the expansion of central balloon 12a, and its eventual melting and rupturing to secure the remnants to the wall of the wellbore.

(68) FIG. 15 shows the path of the plugging fluid 25 and the reaction products 29 through the pressure-operated inflation valves 28. Specifically, the reaction products 29 force the plugging fluid 25 through the pressure-operated inflation valves 28 and then through the weakened sections of the balloon 47 (not shown). The reaction products 29 follow the same path through the pressure-operated inflation valves 28 and the weakened section of the balloon 47 (not shown).

(69) FIG. 16 illustrates the removal of the apparatus from the wellbore 11 through production tube 30 after the wall has been plastered with, and sealed by the melted balloon 120a and end balloons 120b, 120c have been ruptured. It is noted that the remaining portions of the end balloon, 120b (not shown) and 120c which are attached to inflating container 24 are removed with the coiled tubing 14 (not shown).

(70) The method and system of the present invention have been described above and in the attached drawings; however, modifications derived from this description will be apparent to those of ordinary skill in the art and the scope of protection for the invention is to be determined by the claims that follow.