Abstract:
This invention relates to a process for isolating one or more segments of a gravel packed well from other segments to treat the isolated segments and easily re-establish flow from the other segments after the treatment. The treatment includes techniques for enhancing or permanently blocking production from the isolated segment. The process includes the installation of a removable plug and a permeability poison that forms a fluid seal to prevent longitudinal fluid flow along the annular production space outside the tubular production pipe. With wireline or other low-cost wellbore workover systems, access is re-engaged with the secluded formation including removal of plugs and fluid seals within the tubular production pipe. The inventive process allows enhanced recovery of fluids by focusing treatments on problem areas without harming productive segments of the well.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a non-provisional application which claims benefit under 35 USC §119(e) to U.S. Provisional Application Ser. No. 61/148,747, filed Jan. 30, 2009, entitled “In-Situ Zonal Isolation For Sand Controlled Wells,” which is incorporated herein in its entirety. 
     
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
       [0002]    None. 
       FIELD OF THE INVENTION 
       [0003]    This invention relates to producing fluids from a gravel packed well. 
       BACKGROUND OF THE INVENTION 
       [0004]    In oil wells, it is common for sand or other solid gritty materials to be carried from the producing formation along with the oil into the wellbore. Sand or other grit causes problems and wear for the production equipment and preventing the introduction of such solids into the wellbore is very much desired. A common solution to prevent the production of such sand and grit is called “gravel-packing” the well. Gravel packing is basically the installation or packing of coarse sand or gravel material into the annular space between the production tubing/liner and the casing or the formation in an open-hole production arrangement. This gravel packed space extends along the outside of the production tubing/liner, may be the length of hundreds of pipe sections or joints. While most of the production tubing is impervious to liquid, the sections or joints adjacent the production zone are provided with slots or other pre-perforated openings in the peripheral wall. These joints allow the produced liquids to pass from the outside of the production tubing into the interior of the production tubing. These slotted or pre-perforated joints are often screened and/or pre-packed with sand control media and known to those skilled in the art as sand control screens. The interior of the production tubing is where a pump may be disposed to carry or drive the liquids to the surface. Those that are skilled in the art understand that there are a lot of different production methods including free flowing and plunger lift as well as several variations of artificial lift such as gas lift, rod pumps, rotary PC pumps, jet pumps, electric submersible pumps and there are other less common methods of production methods. 
         [0005]    The slotted or pre-perforated joints are commonly referred to as base pipe and typically includes holes or openings with a wire mesh, screen, or pre-packed sand control media around the outside to prevent the sand or gravel from leaking into the production tubing. There are other gravel packing arrangements where the base pipe has many small slits that are sized to prevent the passage of sand, but the function is substantially the same. Gravel packing essentially forms a filter barrier for the fine formation sand or grit, but allow the liquids to pass freely through the interstices into the production tubing and be carried to the surface. However, the sand or gravel does not discriminate between different fluids and there are times when undesirable fluids enter the gravel packing. For example, as a well is produced, water, especially salt water, often encroaches into the hydrocarbon production zone as hydrocarbons are extracted. Typically, hydrocarbons and water are found together underground with water below oil. As the hydrocarbons are withdrawn, the hydrocarbon/water interface rises and it is not uncommon for water to begin to comprise a significant portion of the total fluids produced. However, water can enter virtually anywhere in the completion in the well depending on the geological conditions. Water may enter the mid to upper sections of a producing zone when the upper sections have higher permeability and when the permeability ratios (vertical vs. horizontal) or natural formation fractures favor a situation where water may over-run the tighter producing zones and show up first in mid to upper areas of the completion. 
         [0006]    While the hydrocarbon/water interface may initially be confined to a single production zone, it is also not uncommon for an oil well to be drilled such that several oil bearing zones are accessed by the single well. Each of the hydrocarbon bearing zones may be isolated from one another by impermeable rock formations and each may have and hydrocarbon/water interface. The gravel packing may be exposed to several of these formations and fluids from one may translate along the gravel packing media to enter the production tubing at a different location. This can be a concern as allowing different isolated zones to communicate with one another may create undesirable problems in that one zone may contaminate another. The separate zones may extend for miles so cross contamination may have broad consequences. 
         [0007]    There have been several efforts to stop the production of water in gravel packed wells. Typically, the formation pressure that drives the hydrocarbons toward the low pressure well comes from salt water that is denser than hydrocarbons and, therefore, below the hydrocarbons. As such, the efforts have been focused on closing the gravel packed bed from the water at the bottom of the production zone. What hasn&#39;t been developed is a suitable and effective technique to seal the well from undesirable fluids that are above or in the middle of the target zone while permitting continues production from the target zone. 
       BRIEF SUMMARY OF THE DISCLOSURE 
       [0008]    The invention generally includes a process for isolating and treating a first fluid producing zone of an underground formation in an earthen well where the well includes a second fluid producing zone further into the ground than the first zone and a sand or gravel filter element within an annular production space between a tubular production pipe and the underground formation or casing pipe where access from the surface through the production pipe to the second fluid producing zone is preserved for subsequent production following the isolating and treating procedure. The process more particularly includes installing a wireline or coiled tubing removable plug into the tubular production pipe at a level further into the ground than the first fluid producing zone. A settable, low viscosity permeability poison is injected into the tubular production pipe above the plug and out into the sand or gravel element in the annular production space outside of the tubular production pipe and extending laterally to the casing pipe or formation to fill a longitudinal segment of the sand or gravel element in the annular production space between the first and second fluid producing zones to eventually separate and substantially seal the first and second zones from one another against fluid flow in the sand or gravel element in the annular production space. The low viscosity permeability poison is converted into a fluid seal forming a longitudinal barrier against flow within the sand control screen in the annular production space and a treatment is injected into the tubular production pipe onto the fluid seal and laterally through the annular production space and into the formation at the first fluid producing zone. The interior of the tubular production pipe is then opened up to regain access to the second fluid producing zone by removing portions of the treatment material, the fluid seal and the isolation material within the tubular production pipe so that fluids may enter the production pipe from the second zone and be extracted to the surface past the now treated first fluid producing zone. 
         [0009]    A variation of the present invention is a process for isolating and treating first and second fluid producing zones of an underground formation in an earthen well that includes a third fluid producing zone generally intermediate of the first and second zones where the second zone is most distant from the surface and the first zone is closest to the surface and the well also includes a sand or gravel filter element with an annular production space between a tubular production pipe and the underground formation or casing pipe where access from the surface through the production pipe to the third zone is preserved for subsequent production following the isolating and treating procedures of the first and second zones. This variation includes installing a wireline or coiled tubing removable plug into the tubular production pipe at a level further into the ground than the second fluid producing zone and injecting a treatment into the tubular production pipe which is sealed by at least the plug and laterally through the annular production space and into the formation at the second fluid producing zone. A layer of isolation material is deposited into the tubular production pipe above the plug to form a first low permeability layer therein where at top of the layer is at a level below the first fluid producing zone. A first settable, low viscosity permeability poison is injected onto the isolation material in the production pipe and out into the sand or gravel element in the annular production space outside of the tubular production pipe and extending laterally to the casing pipe or formation to fill a longitudinal segment of the sand or gravel element in the annular production space between the first and second fluid producing zones to eventually separate and substantially seal the first and second zones from one another against fluid flow in the sand or gravel element in the annular production space. The low viscosity permeability poison is then converted into a fluid seal forming a longitudinal barrier against flow within the sand control screen in the annular production space. A treatment may then be injected into the tubular production pipe onto the fluid seal and laterally through the annular production space and into the formation at the first fluid producing zone and then the interior of the tubular production pipe is opened up to regain access to at least the third fluid producing zone by removing portions of the treatment material, the fluid seal and the isolation material within the tubular production pipe so that fluids may enter the production pipe from the third fluid producing zone and be extracted to the surface past the now treated first fluid producing zone. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]    A more complete understanding of the present invention and benefits thereof may be acquired by referring to the follow description taken in conjunction with the accompanying drawings in which: 
           [0011]      FIG. 1  is a vertical and fragmentary cross sectional view of a not to scale prior art production system in a borehole; 
           [0012]      FIG. 2  is a top and fragmentary cross sectional view of a not to scale prior art production system in a borehole; 
           [0013]      FIG. 3  is a vertical and fragmentary cross sectional view of a not to scale production system in a borehole showing the first steps in a process to isolate a non-preferred upper zone in the well 
           [0014]      FIG. 4  is a vertical and fragmentary cross sectional view of a not to scale production system in a borehole showing the completed process for isolating a non-preferred upper zone in the well where the preferred zone is below the isolated zone; 
           [0015]      FIG. 5  is a vertical and fragmentary cross sectional view of a not to scale production system in a borehole showing the first steps in a process to isolate a non-preferred upper zone and a non-preferred lower zone in the well; and 
           [0016]      FIG. 6  is a vertical and fragmentary cross sectional view of a not to scale production system in a borehole showing the completed process for isolating two non-preferred zones where the preferred zone is below at least one of the isolated zones. 
       
    
    
     DETAILED DESCRIPTION 
       [0017]    Turning now to the detailed description of the preferred arrangement or arrangements of the present invention, it should be understood that the inventive features and concepts may be manifested in other arrangements and that the scope of the invention is not limited to the embodiments described or illustrated. The scope of the invention is intended only to be limited by the scope of the claims that follow. 
         [0018]    Turning to  FIG. 1 , a wellbore  10  is shown to be formed deep into the earth  11 . Within the earth  11  are layers of various materials. Some of the layers are porous and permeable and permit fluids such as oil and water and natural gas to transit through the pores and interstitial voids. These layers are sometimes described as reservoir rock as the oil or hydrocarbons tend to move through permeable formations. Other layers in the earth are either without pores or have closed pores and do not permit fluids to easily pass through. These layers tend to seal one permeable layer from another and certain geological structures may capture and hold oil and other hydrocarbons in areas called “traps”. Those deciding where to drill tend to target these hydrocarbon traps and produce oil where it is found in quantities that justify the investment to produce it. 
         [0019]    In  FIG. 1 , a wellbore is generally indicated by the numeral  10  and is shown to have encountered three permeable zones, labeled A, B and C. Between zones A and B is shown an impermeable or substantially impermeable layer  12 . Between zones B and C is shown an impermeable or substantially impermeable layer  13 . The wellbore  10  was drilled with a diameter large enough to accommodate casing pipe  15 . As is well known in the oil business, casing pipe  15  is inserted into position in the wellbore  10  and sealed to the earth  11  and to all the various zones and layers that the wellbore  10  intersects by cement or other grout material that forms a layer  18  around the outside of the casing pipe  15 . The wellbore  15  is also shown to have been perforated by known perforating techniques that typically include shaped charges detonated to form a number of openings through the casing pipe  15  and through the cement layer  18  and also into the earth and into the various layers and zones therein. In the present illustration, the perforations are illustrated as conical shaped perforations  19  with the pointed ends extending into the earth in each of the permeable zones A, B and C. In actuality, perforations take various indescribable shapes with many fractures and fissures to allow and encourage fluids to drain from the formation into the wellbore  10 . With the perforations  19  extending through the wall of the casing pipe  15  and all the way into the formations of the earth  11 , oil and other fluids in the permeable zones A, B and C are able to move through from the permeable zones and into the wellbore  10  until the pressure of the fluid inside the wellbore equalizes with the pressure in the various permeable zones A, B and C. 
         [0020]    While there are situations where the formation pressure is sufficient to drive hydrocarbons to the surface, it is more typical for fluids in the wellbore  10  to be extracted through a production assembly that includes any of various forms of artificial lift including down hole pumps. The production assembly is generally indicated by the numeral  20  and the pump or other form of artificial lift is not shown. While conventional production systems can include a substantial number of elements and provide substantial capability at the bottom of a wellbore, the production assembly  20  is simplified to provide an explanation of the invention and the problems that the invention is intended to overcome. The simplified production assembly  20  includes a production pipe  21  having sand control screen base pipe  25  arranged to be in the vicinity of the producing zones of the wellbore  10 . The production pipe  21  and sand control screen base pipe  25  are connected end to end with an upper packer  22  and a lower packer  23  arranged to seal an annular production space  26  within the interior of the casing pipe  15  and around the sand control screen base pipe  25  possibly including part of the production pipe  21 . It should be noted that sand control base pipe is little more specialized than tubing in that sand control base pipe may include wrapping screens, sand, resin coated sand, sintered metal or other filter materials. A typical sand control screen&#39;s base pipe is perforated or slotted through the majority of the length of the pipe joint. While it is not clear from the drawings, a joint is typically thirty feet or so in length and the perforations and slots may extend the entire length but for several inches from each end so as not to interfere with the collars where the joints are connected. Filter media is applied over the pre-perforated or slotted base pipe and the ends of each joint of base pipe may be indistinguishable from regular tubing joints. In  FIG. 1 , the sand control base pipe  25  has apertures, holes, perforations, slots or similar to allow fluids to pass from the outside to the inside while the production pipe  21  has an impervious wall. The packers  22  and  23  are arranged so that all of the openings in the sand control base pipe  25  and all of the perforations  19  are open to the production space  26  defined between the packers  22  and  23  and no openings in the sand control base pipe  25  nor any perforations  19  are outside of the production space  26 . 
         [0021]    It should be noted that while the well  10  in the illustrated example is provided with casing pipe  15 , the invention is also applicable for open-hole production systems where the production space  26  extends from the production pipe  21  to the formation or to the inner wall of the wellbore  10 . Open-hole production is well known and generally much less expensive than cased production. However, for simplicity in the explanation, the invention is described with casing pipe  15  with the expectation that those skilled in the art will readily understand that the inside of the casing pipe  15  is a substitute for the inner wall of the wellbore  10  and that without the casing pipe  15 , the invention could be directly undertaken with the production space  26  extending fully to the inner wall of the wellbore  10 . 
         [0022]    The sand control base pipe  25  as illustrated includes three production sections  30  which are best explained in conjunction with  FIG. 2 . Turning to  FIG. 2 , base pipe  25  includes a large number of openings  31  to allow fluids to pass from the production space  26  into the interior  36  of the base pipe  25 . Around the outside of the base pipe  25  are a number of spacers  32  which are generally welded to the exterior of the base pipe  25 . Surrounding the base pipe  25  and spaced from the periphery thereof is a wire wrapped screen  34 . In other configurations, it should be noted do not include spacers and a space  35  around the sand control base pipe  25 , but the invention will still generally work the same. The wire wrapped screen  34  creates a large number of small channels through which oil or other fluids may transit from the production space  26  on a path toward the interior  36  of the sand control base pipe  25 . Between the casing pipe  15  and the wire wrapped screen  34  is the production space  26  that is typically packed with sand or gravel. It is preferred that the sand and gravel also fill the perforation tunnels  19  and the space  35 . It should be noted that in certain circumstances, it is very difficult and expensive to fully pack the space around the wire wrapped screen. In these circumstances the formation is allowed to collapse around those portions of the screen over time relying on the screen to keep the sand and grit out of the production tubing. While this is not optimal because the particle sizes against the wire wrapped screen are preferably of a common and selected size to provide maximum porosity while filtering the sand and grit, oil may still be profitably produced and the invention may still be used in this circumstance to isolate portions of the well from other portions. The production space  26  when packed with sand or gravel is sometimes called “gravel packing” or a “packed bed”. The mesh size of the wire wrapped screen  34  is determined in conjunction with the mesh size of the sand or gravel so that the sand or gravel will not pass through the wire wrapped screen  34 , but oil and other fluids may. The gravel or sand basically forms a filter cake that effectively filters any sand or other grit that may be carried by the produced fluids to the perforations  19 . The fluids continue to travel toward the interior  36  of the base pipe  25 , but the formation sand and grit is held back by the sand or gravel in the production space  26 . 
         [0023]    The process of installing the casing pipe  15 , the production assembly  20  including the gravel bed in the production space is all well known. It is only illustrated to set forth what may be accomplished by the present invention. And the primary concern that the present invention addresses is the circumstance when one or more of the production zones A, B or C begins to deliver amounts of undesirable fluids that justify investments into the well to reduce the production of such undesirable fluids. Typically, when an oil or gas well produces a large percentage of water, the costs of lifting, separating and disposing of the produced water can justify the costs of re-working a well to reduce the percentage of produced water at the bottom of the wellbore  10 . By the present invention any portion of the earth formation may be isolated from the production assembly  20  whether the preferred production zone is above, below or between un-preferred production zones. Water production in either oil or gas wells negatively impacts the production rate of the preferred hydrocarbons. Water can take up a large percentage of the flow path reducing the amount of hydrocarbons produced in a given amount of time, and increasing frictional pressure drop and increasing density of the produced fluids thereby reducing the amount of production due to reduced pressure drop at the formation face. It should also be noted that isolating portions of wells is not limited to hydrocarbon production. In wells that are drilled for fresh water, it is possible to have salt water or contaminated fluid in adjacent formations that can be isolated from the desired zone by the present invention. 
         [0024]    To most clearly explain the invention, the illustrated wellbore  10  will be sealed off from zone A and will continue to produce only zones B and C after zone A has been fully closed off from the production assembly  20 . This would be appropriate if zone A had suffered a water breakthrough where very little hydrocarbons could be extracted. At the same time, the production from zones B and C would need to be deemed sufficiently profitable to continue producing from those zones through wellbore  10 . Issues of profitability for zones B and C include current and projected prices for hydrocarbons, the quality of the hydrocarbons, the contaminants that may make the hydrocarbons less valuable, the remaining water cut or percentage of water in the hydrocarbons, the depth of the well and the cost of isolating zone A, the cost of transporting the produced fluids to market and perhaps a dozen other issues. Regardless, human judgment would dictate which wells and which zones would have the inventive procedure implemented thereon. 
         [0025]    Turning to  FIG. 3 , the process of isolating zone A would begin by installing a removable plug  41 . Preferably, removable plug  41  may comprise a material that can be washed away with a chemical treatment such as an acid wash. Alternatively, a plug that may be retrieved with a wireline device is suitable or the plug may be drilled/milled out. The plug  41  is positioned below the zone to be isolated. In  FIG. 3 , the plug  41  is shown to be below the impermeable layer  12  and therefore below zone A. A layer  42  of isolation material such as fine grain sand, ground calcium carbonate, salt, or other materials including even dense fluids, is then deposited upon the plug  41 . The layer  42  of isolation material forms a very low permeability or density balanced barrier to prevent materials that are delivered into the wellbore subsequent to the installation of layer  42  from binding to the plug and complicating the subsequent removal of the plug. The isolation material may be washed out later by circulating fluid or jetting fluid to allow access to the plug as will be discussed later. 
         [0026]    A low viscosity permeability poison is injected into the production tubing  21  and delivered onto the layer  42  so as to flow out of the base pipe  25  and into the annular production space  26  all the way to the inside of the casing pipe  15  to form a fluid seal  44 . The fluid seal  44  is preferably formed by materials that flow through the gravel packing and preferably seal against the interior of the casing pipe  15  and fill the interstices of the sand or gravel. There are known materials that are able to serve the purpose that with the addition of small amounts of a setting compound, heat, or time will rapidly set from a low viscosity fluid to a very high viscosity or crystalline structure. Essentially, this poison converts permeable sand or gravel into impermeable sand or gravel. Preferred materials include sodium silicate or sodium metasilicate which is a stable and low viscosity liquid in neutral solutions, but in acidic or alkaline solutions converts to form a solid precipitate or high viscosity fluid that that kills or poisons the permeability of the gravel pack rendering it nearly impermeable to flow fluid. With fluid seal  44  set in place, the production space  26  is now divided. As such, the upper zone A is available for treatment independent of zone B. Some treatments, such as an acid wash or fracturing with additional proppant enhance fluid production. For example, asphalts build up in the formation and perforations slowing down production. In other circumstances, it is desired to slow or stop fluid production. Such production stopping may include the application of substantial forces that may be applied after the fluid seal is fully set. 
         [0027]    A permanent barrier to prevent the flow of fluids in zone A from entering production assembly  20  is shown in  FIG. 3 . Rather than direct the low viscosity materials of the fluid seal  44  into the formation accessed by the perforations  19  into the earth at zone A, the fluid seal  44  is arranged below the lowest perforations in zone A. With the fluid seal  44  in place and set to have a very high viscosity or crystalline fluid seal  44 , the production blocker  45  may be squeezed at a very high pressure to overcome the inherent formation pressure within zone A and drive the formation blocker  45  through the interstices of the gravel packing and deep into the crevices and fractures within perforations  19 . The production blocker may comprise a micro cement, a resin and may also comprise sodium silicate. Under the higher pressure that may be applied with fluid seal  44  in place, the production blocker  45  is able to more fully fill the production spaces including the perforations  19  even if the materials are the same. It should be noted that it is preferred that the space  35  includes the sand and permeability poison to isolate the zones so that fluids are not able to bypass the seal and pass longitudinally along the sand control base pipe  25  in space  35 . 
         [0028]    The next steps of process relate to opening up fluid communication between the production pipe  21  and the sand control base pipe  25 . Referring now to  FIG. 4 , the materials that form the production blocker  45  are removed from inside the base pipe  25  preferably by irrigation with a circulation of liquids. Chemical treatments such as by directing a stream of suitable acid or caustic through a coiled tubing string or other work string where the dissolved portions of the production blocker  45  and fluid seal  44  are washed up to the surface through the annulus of the production pipe formed outside the coiled tubing string. It should be noted that if water is a suitable material for removing the barrier or production blocker within the interior of the base pipe  25 , water would be preferred over other more expensive and harsher chemicals. Moreover, these elements may also be drilled out. The coiled tubing string or other work string is not shown, but rather the results of the removal of the portions of the production blocker  45 , the fluid seal  44 , the isolation layer  42  and the plug  41  within the production pipe are removed. At the same time, the perforations  19  in zone A are blocked from further production and the system for blocking does not allow fluids from zone A to bypass the fluid seal  44  and blocker  45  because of the cement  18 , the permeable layer  12 . Leaving the fluid seal  44  in place provide extra confidence that fluids in zone A are not allowed to move along a narrow interface of the blocker  45  and the lowest perforations  19  and then descend within the gravel pack to be then drawn into the base pipe  25  through a production section  30 . 
         [0029]    A similar procedure may be used to isolate zone A and C from zone B where zone B is producing desirable fluids but zones A and C are in need of treatment to enhance production or to be shut off. Referring now to  FIG. 5 , a removable plug  51  is installed below the lowest perforation  19  in zone C. A low permeability isolation layer or high density fluid layer  52  may be installed on the plug  51  if there is further production lower in the wellbore. However, in the situation where zone C is the lowest producing formation and it is producing water in a hydrocarbon well, the need to protect the plug  51  with the low permeability isolation material is probably not necessary as the plug will unlikely ever be recovered. A treating string with a packer is positioned adjacent layer  13  and used to squeeze a treatment into zone C. In the drawings, the zone C is desired to be closed to further production and a production blocker  55  is formed by the high pressure insertion of material that extrudes through the gravel packing, the wire wrapped screen, the space between the wire wrapped screen and the periphery of the base pipe and preferably into the perforations  19  in zone C. Upon complete curing or reaction of the production blocker  55 , the wellhole  10  is completely isolated from any fluids in zone C. With the production blocker inside the base pipe  25 , and depending on the distance of the production blocker  55  from zone A, a second isolation layer  62  may be installed directly on the production blocker  55 . With the isolation layer  62  installed, a fluid seal  64  is installed as described previously with a production blocker  65  installed to seal zone A from the wellbore  10 . Again, with zone A sealed from zone B, zone A may alternatively be subjected to a treatment that enhances fluid production in zone A before fluid communication is re-established with zone B. As described in the first embodiment, the production blocker  65  and fluid seal  64  within the base pipe  25  are at least partially removed along with the isolation layer  62  to allow access to the base pipe adjacent zone B as shown in  FIG. 6 . It should be noted that while it is preferred to open the interior of the base pipe  25  using wireline tools or coiled tubing to minimize rig costs and other expenses, drilling out the production blocker  65  within the base pipe  25  is certainly an option that may be used. Also, if no production is intended in zone C or below, the production blocker  55  is not removed from the inside of the base pipe  25 . 
         [0030]    It should be noted that the process has been described to stop production in certain zones within the well, but in many other circumstances, it is desirable to stimulate certain formations without subjecting other zones to such stimulation. The technique for stimulating and isolated section begin by isolating the target zone from the non-target zone. Referring again to  FIG. 3 , if zone A were deemed to be in need of treatment for which it is desirable not to subject zones B and C to the same treatment, a removable plug  41  would be inserted into the base pipe  25  as described before. Layer  42  and fluid seal  44  would also be installed as described before. However, rather than install the production blocker  45 , a treatment such as fracturing materials and pressure may be applied or an acid treatment or various kinds of washing may be performed. The inventive technique of the present invention provides for isolation of zone A without forgoing subsequent production of zones B and C by removing the fluid seal within the base pipe  25  after the treatment of zone A has been completed. Production would then resume after removal of the fluid seal  44 , the layer  42  and the plug  41  as described before. As should be easily understood, the invention provides for isolating one zone from another and then being able to apply materials under pressure into isolated zones. The fluid seal  44  that remains outside of the base pipe  25  essentially operates as a packer within the casing  15  or to the formation when packers were not originally included in the completion. Once in place with the base pipe  25  opened to the desirable zones, production may be optimized. 
         [0031]    In closing, it should be noted that the discussion of any reference is not an admission that it is prior art to the present invention, especially any reference that may have a publication date after the priority date of this application. At the same time, each and every claim below is hereby incorporated into this detailed description or specification as additional embodiments of the present invention. 
         [0032]    Although the systems and processes described herein have been described in detail, it should be understood that various changes, substitutions, and alterations can be made without departing from the spirit and scope of the invention as defined by the following claims. Those skilled in the art may be able to study the preferred embodiments and identify other ways to practice the invention that are not exactly as described herein. It is the intent of the inventors that variations and equivalents of the invention are within the scope of the claims while the description, abstract and drawings are not to be used to limit the scope of the invention. The invention is specifically intended to be as broad as the claims below and their equivalents. 
       REFERENCES 
       [0033]    All of the references cited herein are expressly incorporated by reference. The discussion of any reference is not an admission that it is prior art to the present invention, especially any reference that may have a publication data after the priority date of this application.