Abstract:
Tools and methods for completing a wellbore that comprise an isolation packer with a particulate filter and inflatable element. The isolation packer is adapted to direct a gravel laden slurry to the particulate filter, where the filter removes a substantial amount of the particulate matter from the gravel laden slurry thereby producing an inflating fluid that is substantially free of particulate matter. The inflating fluid then inflates the inflatable element thereby creating a seal in the wellbore.

Description:
TECHNICAL FIELD  
       [0001]     This invention generally relates to inflatable packers used to complete subterranean wells and in particular to hydraulically actuated inflatable packers. More specifically, this invention relates to hydraulically actuated inflatable packers that are inflated by a fluid filtered from a gravel laden slurry or other fluid with suspended solids.  
       BACKGROUND OF THE INVENTION  
       [0002]     Oil and natural gas may be obtained from subterranean geologic formations, referred to as reservoir, by drilling wells that penetrate hydrocarbon-bearing formations. In order to obtain hydrocarbons from a wellbore, the well usually must be completed.  
         [0003]     Well completion involves the design, selection, and installation of equipment and materials in or around a wellbore for conveying, pumping, or controlling the production or injection of fluids from and/or to the wellbore. After a well has been completed, production of oil and gas may begin. Sand or silt flowing into the wellbore from unconsolidated formations may lead to an accumulation of fill within the wellbore which may cause a reduction of production rates and damage to surface and subsurface production equipment. The fill, often referred to as migrating sand, has the possibility of packing off around subsurface production equipment, or may enter the production tubing and therefore enter production equipment. Sand is highly abrasive, and if it enters production streams, it may cause the erosion of tubing, flowlines, valves and other processing components and equipment. Erosion and abrasion caused by sand production often increases operational and maintenance expenses, and in severe cases may lead to a total loss of the well. Gravel packing is a means of controlling sand production. Gravel packing is the placement of relatively large sand (i.e., “gravel”) around the exterior of a sand screen or liner, which includes slotted sand screens, perforated sand screens, and various other liner types and screens. The gravel acts as a filter to remove formation fines and sand from oilfield fluids.  
         [0004]     A gravel pack completion known in the art comprises a sand screen that is placed in the wellbore and positioned within an unconsolidated formation. The sand screen may be connected to a tool that includes a production packer and a cross-over. The tool is connected to a work string or a production tubing string. Gravel is then pumped in a slurry down the tubing and through the cross-over, thereby flowing into the annulus between the sand screen and the wellbore. The slurry comprises a liquid supporting suspended solids. The solids are often referred to as “gravel”. The liquid leaks off into the formation and/or through the sand screen, which is sized to prevent the solids in the slurry from flowing through. Thus the solids are deposited in the annulus around the sand screen where it forms a gravel pack. The sand screen prevents the gravel pack from entering into the production tubing. The gravel must be sized for proper containment of the formation sand, and the sand screen must be designed in a manner to prevent the flow of the gravel through the sand screen.  
         [0005]     Often during well completions there is a need to seal off sections of the wellbore. One reason to seal off a section of a wellbore is the need to isolate those areas in which an adequate gravel pack can not be obtained, such as below the bottom of the gravel pack screens where adequate circulation is difficult to achieve. Another reason to seal off a section of a wellbore is that in some formations, such as across a major or minor shale section, a gravel pack completion is not desirable. Still another reason to seal off a section of a well bore is because when one or more sections are to be completed and another section is not going to be completed, the non-completed section often needs to be isolated from the sections that will be completed. This is due to the fact that when non-completed sections are not isolated, the gravel, which is tightly packed around the gravel pack screens after a gravel pack, may be able to migrate to these non-completed sections, thereby limiting the effectiveness of the gravel pack completion. Another reason to isolate a section of the wellbore is to prevent or limit acceleration of the gravel migration effect due to the flow of produced fluids. Sand screens exposed to gravel migration due to the flow of produced fluids may experience direct production of formation sand which could result in equipment damage, formation collapse and even the loss of the well.  
         [0006]     Well known in the art are inflatable packers, usually comprising an annular elastomeric bladder, which have been used to seal off sections of wellbores for the reasons discussed above. When the bladder is filled by a by a pressurized fluid, it inflates the packer causing the exterior of the elastomeric body to seal against the wellbore. This produces a wellbore seal that prohibits fluid flow past the packer.  
         [0007]     A problem with inflatable packers known in the art is the difficulty of sending fluid to the bladder to inflate the bladder. The time consumed in using known inflatable packers includes the time needed for an extra step either prior to the gravel pack step or after the gravel pack step to send a specialized tool down the wellbore to inflate the packer.  
         [0008]     Thus, there is a need for an improved inflatable packer which reduces the known problems in sending fluid to the bladder to inflate the bladder, and eliminates the need for an extra step either prior to or after a gravel pack to inflate the bladder.  
       SUMMARY OF THE INVENTION  
       [0009]     The present invention describes tools and methods of completing a wellbore that comprise an isolation packer with a particulate filter and inflatable element. The isolation packer is adapted to direct a gravel laden slurry to the particulate filter, where the filter removes a substantial amount of the particulate matter from the gravel laden slurry thereby producing an inflating fluid that is substantially free of particulate matter. The inflating fluid then inflates the inflatable element thus creating a seal in the wellbore.  
         [0010]     This invention offers a number of benefits over conventional wellbore completion tools. Usually a pre-gravel pack trip would be undertaken to isolate a sump area, for instance, with a cement plug or an open hole packer. This pre-gravel pack trip comprise additional steps that are costly, time consuming and are often difficult to perform and unreliable in their outcome. The present invention provides a means of achieving the desired results in the same trip into the well as the gravel pack operation. The ability to inflate the inflatable isolation packer during a gravel pack completion can save time and expense by eliminating an additional trip into the well. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]     The above advantages as well as specific embodiments will be understood from consideration of the following detailed description taken in conjunction with the appended drawings in which:  
         [0012]      FIG. 1  is a cross section of a wellbore showing a prior art gravel pack completion apparatus.  
         [0013]      FIG. 2  is a cross section of a wellbore showing a gravel pack completion apparatus that includes an embodiment of the present invention.  
         [0014]      FIGS. 3A and 3B  are cross sections of a wellbore showing a gravel pack completion with both a typical isolation packer ( FIG. 3A ) and with a cup packer ( FIG. 3B ) with the particulate filter located near an uphole end of the conduit.  
         [0015]      FIG. 4  is a cross section of a wellbore showing an embodiment of the present invention with the inflatable element shown in an inflated state.  
         [0016]      FIG. 5  is a partial cut away view of another embodiment of the present invention comprising an alternative channel.  
         [0017]      FIG. 6  is a partial cut away view of the present invention comprising an alternative channel with the particulate filter located near an uphole end of the alternative channel.  
         [0018]      FIG. 7  is a partial cut away view of the alternative channel embodiment of the present invention showing the inflatable element in an inflated state.  
         [0019]      FIG. 8  is a cross section of a wellbore showing another embodiment of the present invention in an openhole completion.  
         [0020]      FIG. 9  is a cross section of a wellbore showing the embodiment of the present invention in an openhole completion with the inflatable element in an inflated state. 
     
    
       [0021]     References in the detailed description correspond to like references in the figures unless otherwise indicated.  
       DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0022]     Referring to the attached drawings,  FIG. 1  is a depiction of the prior art and illustrates a wellbore  10  that has penetrated a subterranean zone  12  that includes a productive formation  14 . The wellbore  10  has a casing  16  that has been cemented in place. The casing  16  has a plurality of perforations  18  which allow fluid communication between the wellbore  10  and the productive formation  14 . A well tool  20  is positioned within the casing  16  in a position adjacent to the productive formation  14 , which is to be gravel packed.  
         [0023]     The present invention can be utilized in both cased wells and open hole completions, as well as vertical wells and non-vertical wells. For ease of illustration of the relative positions of the producing zones in  FIGS. 1-4 , a cased well having perforations will be used. More detailed illustrations of the invention being utilized in an open hole completion are shown in  FIGS. 8-9 .  
         [0024]     Still referring to  FIG. 1 , the well tool  20  comprises a tubular member  22  attached to a production packer  24 , a closing sleeve  26 , and one or more sand screen elements  28 . Blank sections of pipe may be used to properly space the relative positions of each of the components. An annulus area  34  is created between each of the components and the wellbore casing  16 . The combination of the well tool  20  and the tubular string extending from the well tool to the surface can be referred to as the production string.  
         [0025]     Still referring to  FIG. 1 , in a gravel pack operation the packer  24  is set to ensure a seal between the tubular member  22  and the casing  16 . Gravel laden slurry is pumped down the tubular member  22 , exits the tubular member through ports in the closing sleeve  26  and enters the annulus area  34  below the production packer  24 . In one typical embodiment the particulate matter (gravel) in the slurry has an average particle size between about 40/60 mesh-12/20 mesh, although other sizes may be used. Slurry dehydration occurs when the carrier fluid leaves the slurry. The carrier fluid can leave the slurry by way of the perforations  18  and enter the formation  14 . The carrier fluid can also leave the slurry by way of the sand screen elements  28  and enter the tubular member  22 . The carrier fluid flows up through the tubular member  22  until the closing sleeve  26  places it in the annulus area  36  above the production packer  24  where it can leave the wellbore  10  at the surface. Upon slurry dehydration the gravel grains should pack tightly together. The final gravel filled annulus area is referred to as a gravel pack.  
         [0026]     An area that is prone to developing a void during a gravel pack operation is the area  42  below the lowest sand screen element  28 , sometimes referred to as the “sump”. A gravel pack void in the sump  42  is particularly problematic in vertical wells in that it can allow the gravel from above to settle and fall into the voided sump.  
         [0027]     Production of fluids from the productive formation  14  can agitate or “fluff” the gravel pack and initiate the gravel to migrate and settle within the sump  42 . This can lead to the creation of voids in the annulus areas  38  adjacent to the sand screen elements  28  and undermine the effectiveness of the entire well completion.  
         [0028]     As used herein, the term “sand screen” refers to wire wrapped screens, mechanical type screens and other filtering mechanisms typically employed with sand screens. Sand screens need to be have openings small enough to restrict gravel flow, often having gaps in the 60-12 mesh range, but other sizes may be used. Sand screens of various types are produced by Halliburton, among others, and are commonly known to those skilled in the art.  
         [0029]      FIG. 2  illustrates one particular embodiment of the present invention where an upper set of perforations  60  and a lower set of perforations  62  will be completed utilizing a gravel pack completion. The lower set of perforations  62  will be isolated from the upper set of perforations  60 . An inflatable isolation packer  50  is run into the wellbore  10  below the lowest sand screen element  28 . A conduit  52  extends from the gravel inflated isolation packer  50  and provides communication with the annulus area  38  that will be gravel packed. The conduit  52  may be generally referred to as a passageway, and more specifically referred to as a shunt tube. A second conduit  53  may be utilized below the isolation packer  50 .  
         [0030]     Between the conduit  52  and the gravel inflated isolation packer  50  is a particulate filter  54 . Likewise, a particulate filter  59  is placed between conduit  53  and the isolation packer  50 . In this way, either or both of the conduits  52 ,  53  allow gravel laden slurry to travel from the annulus area  38  to the particulate filters  54 ,  59  where the gravel laden slurry is filtered, thereby providing an inflating fluid. The inflating fluid is then communicated to an inflatable element  56  that provides the sealing mechanism between the tubular member  22  and the casing  16 . The inflatable element  56  may be an expandable bladder. The particulate filter  54  could be any device known in the art that separates the particulate matter in the gravel laden slurry from the carrying fluid. Some examples of particulate filters include, but are not limited to: wire-wrapped screens and wire meshes.  
         [0031]     A conduit, such as conduit  52  and/or conduit  53 , is just one way of enabling the communication of the gravel laden slurry to enter the inflatable isolation packer  50 . Other embodiments can be used, such as connecting the inflatable isolation packer  50  to a flow channel which is integral to the screen, or a shunt tube. All of these embodiments would include a particulate filter to prevent particulates such as gravel from entering the inflatable element  56 . In addition, all of these embodiments may include a check valve device to prevent any reverse flow out of the inflatable isolation packer  50 .  
         [0032]     The inflation of the inflatable element  56  will typically be done with a fluid that is filtered from a gravel laden slurry. This fluid will be an inflating fluid that is substantially free of particulates such as gravel. The inflation of the inflatable element  56  can be performed in conjunction with a gravel pack completion operation of the well.  
         [0033]     The inflatable element  56  may be constructed utilizing an inner elastomeric element that retains the pressurized fluid that is used to inflate the packer. The inflatable element may comprise more than one layer of material, such as utilizing an expandable mesh as an outer layer for durability. Often a plurality of metal reinforcing members can be located in the annulus between the elastomeric element and the outer expandable mesh, these provide additional strength to the packer and can improve reliability. The typical construction can be in the manner of conventional packers, these methods and materials being well known to those skilled in the art.  
         [0034]      FIGS. 3A and 3B  illustrate alternate embodiments of the invention where the particulate filter  54  is no longer located adjacent to the inflatable element  56 , but rather is now located near the uphole end of the conduit  52 . The particulate filter  54  may be located at various locations on the well tool  20  so long as the particulate filter is able to filter the particulates from the gravel slurry so that an inflating fluid is produced that is substantially free of particulate matter and can be used to inflate the inflatable element  56 . Multiple conduits may be used, one or more with ports as depicted in  FIG. 2  in addition to one or more without ports as shown in  FIG. 3A , as long as at least one conduit supplies inflating fluid through a particulate filter that can inflate the inflatable element.  
         [0035]      FIG. 3B  shows the use of a cup packer  55  placed below the entrance to conduit  52  but above the first opening of sand screen elements  28 . As is known in the arts, the use of a cup packer, such as cup packer  55 , creates a pressure seal between well tool  34  and the well bore wall  16  except for the passage way through the conduit, such as conduit  52 , or the conduits allowing a forced flow through the conduit or conduits.  
         [0036]      FIG. 4  illustrates the embodiment of the invention as described in  FIG. 2  after a gravel pack operation has been performed. The inflatable element  56  of the inflatable isolation packer  50  is expanded and provides a seal between the tubular member  22  and the casing  16 . The upper and lower set of perforations  60  and  62  have been properly gravel packed and protected from the producing formation  14 . The inflatable isolation packer  50  acts to isolate the gravel pack completed lower set of perforations  62  from the gravel pack completed upper set of perforations  60 . Also shown in  FIG. 4  is the use of a second isolation packer  150  which can be used and operated in a manner similar to isolation packer  50 .  
         [0037]     For ease of installation and to ensure proper placement relative to the components of the well tool  20 , the conduit  52  that extends from the inflatable isolation packer  50  will typically be attached to the exterior of the well tool  20  in some manner, such as by welding. It is also possible for the conduit  52  to be replaced by a fluid pathway forming an alternative channel within a sand screen element, as described with respect to  FIGS. 5-7 . Also, the particulate filters may be located adjacent or near the inflatable element  56 .  
         [0038]     Referring now to  FIG. 5 , there is depicted a partial cut away view of an apparatus  64  that is an alternative channel embodiment of the invention. Apparatus  64  has an outer tubular  66 . A portion of the side wall of outer tubular  66  is an axially extending production section  68  that includes a plurality of openings  70 . Another portion of the side wall of outer tubular  66  is an axially extending nonproduction section  72  that is distinguished from the production section  68  by the lack of openings  70 . It should be noted by those skilled in the art that even though  FIG. 5  has depicted openings  70  as being circular, other shaped openings may alternatively be used without departing from the principles of the present invention. In addition, the exact number, size and shape of openings  70  are not critical to the present invention, so long as sufficient area is provided for fluid production therethrough and the integrity of outer tubular  66  is maintained.  
         [0039]     Still referring to  FIG. 5 , disposed within outer tubular  66  and on opposite sides of each other is one or more channels  74 , only one channel  74  being visible. Channels  74  provide circumferential fluid isolation between production section  68  and nonproduction section  72  of outer tubular  66 . Channels  74  may be generally referred to as passageways.  
         [0040]     Still referring to  FIG. 5 , disposed within channels  74  is a sand control screen assembly  78 . The sand control screen assembly  78  may include a base pipe  80  that has a plurality of openings  82  which allow the flow of production fluids into the production tubing. The exact number, size and shape of openings  82  are not critical to the present invention, so long as sufficient area is provided for fluid production and the integrity of base pipe  80  is maintained. Positioned around base pipe  80  is a fluid-porous, particulate restricting, sintered metal material such as plurality of layers of a wire mesh that are sintered together to form a porous sintered wire mesh screen  84 . Sand screen  84  is designed to allow fluid flow therethrough but prevent the flow of particulate materials of a predetermined size from passing therethrough. It should be understood by those skilled in the art that other configurations of the sand screen assembly  78  may be used in conjunction with the alternative channel embodiment  64  of the invention, for instance, the sand screen assembly may also have a screen housing located between the channels  74  and the sand screen  84 , or different screening materials may be used in stead of the sand screen  84 .  
         [0041]     Still referring to  FIG. 5 , in this embodiment, the channels  74  are analogous to the conduit  52  from  FIGS. 2-4 , in that a gravel laden slurry may travel down the channels  74  to a particulate filter  54 , which filters out particulates such as gravel. Once the gravel laden slurry is filtered, a substantially particulate-free fluid thereby communicates with an inflatable isolation packer  50  and expands inflatable element  56 .  FIG. 6  shows another embodiment of the alternative channel apparatus  64  wherein the particle filter  54  is located nearer the uphole end of the alternative channel  74 , instead of being adjacent to the inflatable isolation packer  50 .  FIG. 7  shows the alternative channel apparatus  64  with the inflatable element  56  expanded to form a seal with the casing  16  to isolate the annular area  38  from the space  86  below the packer  
         [0042]      FIG. 8  illustrates an embodiment of the gravel inflated isolation packer  50  utilized in an openhole environment. This embodiment comprises a tubular member  22 , a conduit  52 , two particulate filters  54 , an expandable element  56 , an upper packer head  88 , and a lower packer head  90 . This illustration shows an embodiment of the present invention wherein the conduit  52  extends out both the upper packer head  88  and the lower packer head  90 . The conduit  52  provides two pathways, one for communication to the expandable element  56 , and the second for communication to annular areas  92  and  94 .  
         [0043]      FIG. 9  shows the inflatable isolation packer  50  as illustrated in  FIG. 8  and described above with the inflatable element  56  in an inflated state and filled with inflating fluid. The inflated inflatable element  56  forms a seal between in the wellbore thereby isolating annular area  92  from annular area  94 .  
         [0044]     The inflatable isolation packer  50  acts to isolate a first zone from a second zone within the well. In  FIG. 4 , an annulus area that is gravel packed is being isolated from a lower annulus area of the well that is also gravel packed. Other embodiments can be used to separate a gravel packed annulus area from a non-gravel packed annulus area, a gravel packed annulus area from a sump area or other combinations such as these. In other embodiments, a lateral wellbore may be isolated from a main wellbore, multiple lateral wellbores may be isolated from each other, and length of a lateral wellbore being gravel packed may be effectively shortened. The ability to inflate the inflatable isolation packer  50  during a gravel pack completion can save time and expense by eliminating an additional trip into the well.  
         [0045]      FIGS. 1-3  shows the invention used between two gravel packed zones, whereby the invention is isolating the two gravel packed zones from each other. This embodiment can be used to selectively work on or produce from the separate zones.  
         [0046]     In another embodiment the invention may be placed below the lowest perforation or at the bottom of the well. This embodiment may be used to isolate the lower areas from the completed zones without permanently reducing the total depth of the well. Thus, the well could be functionally plugged back to where the inflatable isolation packer was located and leaving open the option of removing the inflatable isolation packer for the completion of deeper zones in the future.  
         [0047]     The discussion and illustrations within this application may refer to a vertical wellbore that has casing cemented in place, or is an openhole bore, and comprises casing perforations to enable communication between the wellbore and the productive formation. It should be understood that the present invention can also be utilized with wellbores that have an orientation that is deviated from vertical.  
         [0048]     The particular embodiments disclosed herein are illustrative only, as the invention may be modified and practiced in different but equivalent manners apparent to those skilled in the art having the benefit of the teachings herein. Furthermore, no limitations are intended to the details of construction or design herein shown, other than as described in the claims below. It is therefore evident that the particular embodiments disclosed above may be altered or modified and all such variations are considered within the scope and spirit of the invention. Accordingly, the protection sought herein is as set forth in the claims below.