Patent Publication Number: US-6341654-B1

Title: Inflatable packer setting tool assembly

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates generally to a method of mixing fluids in a well bore so that the resultant mixture may be used to effectuate a change in a downhole tool. Specifically, the method of the present invention relates to setting an inflatable packing device or packer at a location in a well bore, and an apparatus or assembly usable for performing the method. 
     Many downhole devices are actuated or operated in response to the application of pressurized fluid. Examples of these devices include hydraulically set packers and liner hangers, hydraulic stage cementing collars, pressure actuated perforating gun firing heads, and inflatable packers. In all of these devices, the application of pressurized fluid, to the device, effectuates a change in the device. Hydraulically set packers and liner hangers deploy slips and packing elements in response to the proper application of pressurized fluid. Stage cementing collars shift internally so as to communicate the internal diameter of well bore casing with the outer diameter of that casing. Perforating gun firing heads initiate detonation in the gun in response to the application of fluid pressure. The common element in all of these types of devices is that when pressurized fluid is communicated to the device, that communication effectuates a utilitarian change to the device. Inflatable packing devices such as packers, plugs, bridge plugs, and the like are commonly utilized in the operation or maintenance of subterranean wells. These inflatable packing devices normally comprise an inflatable elastomeric bladder concentrically disposed around a central body portion such as a tube or mandrel. Typically, a sheath of reinforcing slats or ribs is concentrically disposed around the bladder and a thick-walled elastomeric packing cover is concentrically disposed around at least a central portion of the sheath. Such inflatable packing devices may be deployed in a well bore by using tubing or a downhole electric wireline to support the device and to lower the device to a location in the well bore. Typically the inflatable packing device is connected to the electric wire line or tubing at the bottom of a downhole pump device. An assembly of these components is lowered into the well bore at a location below the extent of the production tubing. 
     Pressurized fluid may be pumped to the inflatable packing device from the top of the well through a pumping line. Alternatively, the inflation fluid (e.g., fresh water) may be transported to the vicinity of the inflatable packing device and then pumped into the inflatable packer. After the inflatable packing device is sufficiently inflated to seal the well bore, it is released from the electric wireline or tubing, and the electric wireline or tubing is retrieved from the well bore 
     SUMMARY OF THE INVENTION 
     Among several objects of the invention, a general object of the invention is to provide an improved downhole apparatus for inflating and/or setting an inflatable packing device or packer in a well bore. It is another general object of the invention to provide an improved method of inflating and/or setting an inflatable packer in a well bore. It is yet another general object of the invention to provide a fluid supply housing adapted for use with existing downhole equipment and/or installations. 
     An inflatable packer setting tool assembly, according to the invention, is lowerable into a subterranean well bore and operable to set an inflatable packer therein. The tool assembly includes an inflatable packer setting tool and a fluid supply housing. The setting tool is releasably interconnected to an inflatable packer, and includes a pump that is fluidly interconnected with the inflatable packer and operable to inflate the inflatable packer. The setting tool may be one of variety of setting tools commercially available in the industry. In one aspect of the invention, at least one fluid supply housing is provided that is adaptable or retrofittable onto such a variety of existing setting tools. 
     The fluid supply housing is interconnected with the setting tool and includes an inflation fluid passageway that has an inlet and an outlet that is fluidly interconnected with a suction side of the pump. The inlet is fluidly interconnected to a source of first inflation fluid present in the well bore when the setting tool assembly is lowered into the well bore. The first inflation fluid source may be surrounding well bore fluid or may be a volume of fluid (e.g., bailed fluid) lowered from the surface (e.g., fresh water lowered with the setting tool assembly). Preferably, the supply housing includes a filter housing through which the second inflation fluid must pass prior to passing through the inflation fluid passageway. More preferably, the supply housing has an outer wall which has a fluid inlet (e.g., a plurality of apertures) that fluidly communicates the inflation fluid passageway with the source of the first inflation fluid. 
     The supply housing also includes a reservoir(s) for containing a second inflation fluid (e.g., a water-soluble oil). Preferably, the reservoir includes a spring-loaded movable piston that allows for the volume of the second inflation fluid in the reservoir to vary (e.g., due to thermal expansion of the second inflation fluid). The reservoir has an outlet that is interconnected with the inflation fluid passageway. Thus, the setting tool (i.e., the pump) is operable to draw first and second inflation fluids from the supply housing and to deliver a mixture of the first and second inflation fluids to the inflatable packer so as to inflate inflatable packer. The fluid passageway may be configured so as to pass or deliver a predetermined concentration of one inflation fluid to a second inflation fluid (e.g., 5 to 1, or 10 to 1). This may be done by sizing certain components accordingly, employing one or more metering orifices, and/or employing a venturi device or other fluid control devices (e.g., a dedicated injection pump). 
     A fluid supply housing, according to the invention, is retrofittable onto an existing setting tool and/or an existing electrical wireline. In one embodiment, the supply housing includes an adapter that may be fluidly and/or electrically engageable or interconnectible with a setting tool. Further, the supply housing may include a portion of an electrical circuit that extends from an interface between the supply housing and the electrical wire line, to an interface between the supply housing and the setting tool. With this embodiment, the electrical wireline may be used to electrically interconnect or to power the setting tool. 
     A method of setting an inflatable packing device in a well bore, according the invention, includes first releasably connecting a setting tool with an inflatable packer (i.e., such that a pump of the setting tool is fluidly interconnected with the inflatable packer) and interconnecting a fluid supply housing with the setting tool, to form a setting tool assembly. Preferably, a reservoir of the supply housing is provided with an inflation fluid such as a water-soluble oil. Further, the setting tool assembly may be structurally and electrically interconnected with a downhole electric wire line. The electric wire line may then be used to lower the setting tool assembly into the well bore at a location wherein a second inflation fluid is present, and such that the pump of the setting tool is in fluid communication with the second inflation fluid. The pump is then operated to draw the first and second inflation fluids and to deliver a mixture of the first inflation fluid and the second inflation to the inflatable packer, thereby inflating the inflatable packer. Preferably, the method includes the step of mixing the first inflation fluid and the second inflation fluid to create a predetermined mixture, and wherein the step of operating the pump delivers a volume of the mixture to the packer to inflate the packer therewith. After operating the pump, the inflatable packer may be released from the setting tool and the setting tool and the supply housing may be raised from the well bore. 
     In one application, the mixture consists of at least five parts well bore fluid (e.g., brine, water, condensate, etc.) to one part water-soluble oil. Alternatively, the mixture may be composed of a first inflation fluid having a relatively high volumetric coefficient of thermal expansion but relatively good lubricity properties, and a second inflation fluid having a relatively low volumetric coefficient of thermal expansion and relatively poor lubricity. The resulting mixture is an improved inflation fluid which promotes efficiency, longer life of components, and reliability. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an elevation view of an inflatable packer setting tool assembly according to the invention. 
     FIG. 2 is a cross-sectional view along line  2 — 2  of FIG.  1 . 
     FIGS. 3A-3D are longitudinal sectional views of the inflatable packer setting tool assembly along line  3 — 3  of FIG.  2 . 
     FIG. 4 is a schematic illustration of the inflatable packer setting tool assembly. 
     FIGS. 5A-5D are elevation view of a well bore illustrating a method of setting in inflatable packer using the inflatable packer setting tool assembly. 
     FIG. 6 is a schematic illustration of an alternate embodiment of the inflatable packer setting tool assembly. 
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS 
     FIGS. 1-4 depict a downhole apparatus  11  and specific components of the downhole apparatus  11 , each embodying the invention. Referring first to the schematic illustration of FIG. 4, the downhole apparatus  11  is an inflatable packer setting tool assembly  11  particularly usable in lowering an inflatable packing device or packer  17  to a location in a well bore, in inflating the inflatable packer  17  with an inflation fluid, and then in setting the inflatable packer  17  therein. 
     For purposes of description, the tool assembly  11  and components of the tool assembly  11  depicted in the drawings are referred to as having an upper or uphole end and a lower or downhole end. The upper or uphole end is used to refer to the end closest to the surface of a well bore when the tool assembly  11  or the component of the tool assembly  11  is situated in the well bore. The lower or downhole end is used to refer to the end that is opposite the uphole end and farthest from the surface of the well bore. 
     The tool assembly  11  includes a fluid supply subassembly  81  having a fluid housing  13  connectable at an uphole end, end with a downhole electrical wire line  53 . The connection is preferably made using a conventional connectable interface device or wireline connection means  55  and a teardrop boot  99 . Thus, the setting tool assembly  11  is adapted for use with existing electrical wireline installations and, more particularly, may be retrofitted onto such existing installations. At a downhole end, the fluid housing  13  is connectable to an inflatable packing setting tool  15 . Further, the setting tool  15  is detachably connected to an inflatable packer  17 . 
     It will be understood that the tool assembly  11  of the invention is usable with a variety of conventional inflatable packing devices known in the art including, but not limited to, such devices commonly known as packers, plugs, bridge plugs and the like. Hereinafter, the terms “packer” and “packing device” shall mean any of such packers, plugs, bridge plugs and other inflatable packing devices. 
     The setting tool  15  depicted in the drawings is a direct drive, electric pump setting tool  15  that is currently available in the marketplace. The setting tool  15  includes a preferably metallic tool housing  31  containing therein, a positive displacement type pump  23  and an electric motor  21  (see e.g., FIG.  4 ). The tool housing  31  also contains a motor controller and a variety of electrical components hardware and instrumentation. These components are indicated collectively by reference numeral  19  in the schematic of FIG.  4 . The electrical components  19  are electrically powered or otherwise communicate with the electrical wire line  53  via a circuitry  53   a  that extends from the electrical wireline  53 , through boot  99  and the supply housing  13 , and into the tool housing  31 . 
     In an alternative embodiment, the setting tool assembly  11  may be provided with a conventional slickline pump preferably in combination with an intensifier. Such an assembly is generally known and may be readily incorporated with the present invention by one skilled in the art, upon viewing the Drawings and reading the Description provided herein. 
     Referring to FIG. 4, the pump  23  has a pump suction or inlet  33  preferably equipped with a screen apparatus or filter (not shown) and a pump discharge or outlet  27 . An inlet fluid passageway  25  is formed in the tool housing  31  and extends from the uphole end of the tool housing  31  to the pump inlet  33 . In some embodiments, the fluid passageway  25  will be formed to provide a tortuous fluid path that is conducive to mixing of fluid flowing therethrough. On the discharge side of the pump  23 , a discharge passageway  35  is provided which extends from the pump outlet  27  to the downhole end of the tool housing  31 . As shown in FIG. 4, a check valve  37  is preferably installed in the discharge passageway  35  to prevent backflow. The tool housing  31  is detachably attached to a packer housing  39  for the inflatable packer  17 , in a manner, whereby the discharge passageway  35  fluidly communicates with the interior of the inflatable packer  17 . Further, the connection interface between the inflatable packer  17  and the discharge passageway  35  is provided with a pressure sensitive means (e.g., shear pins) which allows for detaching or release of the tool housing  31  from the packer housing  39  when the inflatable packer  17  is sufficiently inflated to seal the well bore  51  or to otherwise perform its intended function. 
     As best shown in FIGS. 3A and 3B, the supply housing  13  of the present invention is structurally and electrically connectable to the electrical wire line  53  using a common adapter or wireline connection device  55 . Referring specifically to FIG. 3B, the circuitry  53   a  may be extended or run from the electrical wireline  53  into the supply housing  13 . In this way, the supply housing  13  of the present invention may be adapted for use with a variety of existing electrical wireline constructions. It should be noted, however, that the inflatable packer setting tool assembly  11  of the invention may be further adapted for use with other lowering or supporting means such as a tail pipe and tubing string as described in U.S. Pat. No. 5,718,292 (hereby incorporated by reference). The modifications to the tool assembly  11  and, more specifically, to the supply housing  13  to retrofit the inventive supply housing  13  onto such an existing structure will be apparent to one skilled in the art, upon reading the Description and viewing the Drawings. 
     As best shown by FIGS. 3C and 3D, the fluid housing  13  is structurally, electrically and fluidly interconnectible with the tool housing  31  at the downhole end. Structurally, the downhole end of the fluid housing  13  is provided by an adapter  41  that is configured to sealingly engage the uphole end of the tool housing  31  and may be detachably attached thereto via a plurality of set screws  57  (or other conventional fasteners). Further, the circuitry  53   a  is routed through a passageway or electrical conduit  83  which extends from the supply housing  13  into the tool housing  31 . Thus, in one aspect of the invention, a supply housing  13  is provided that is retrofittable onto or with an existing conventional tool housing (such as the tool housing  31  depicted in the drawings) and also with an existing electrical wire line (such as the electrical wire line  53  depicted in the drawings). In another aspect of the invention, a supply housing  13  is provided that is structurally, electrically and fluidly adaptable for use with an existing electrical wire line and/or setting tool, and more generally, adaptable with an existing setting tool assembly. 
     The supply housing  13  is preferably at least one cylindrical metallic housing that contains, among other components, at least one cylindrical reservoir  45  extending substantially the length of the housing  13  and at least one cylindrical filter housing  43  disposed concentrically about and spaced radially outward from cylindrical reservoir  45 . The reservoir  45  has an uphole end or opening that is sealed by a movable piston  47 . The piston  47  is longitudinally biased by a spring mechanism  49  having a fixed end fixedly attached to the housing  13  and a floating end attached to the piston  47 . The downhole end of the reservoir  45  is closed by the adapter  41 , save for a reservoir outlet  65  that opens into a longitudinally extending fluid passageway  63 . As best shown in FIG. 3C, the fluid passageway  63  is formed centrally through the adapter  41  and includes a conventional metering orifice  65  positioned just downstream of the reservoir outlet  61 . 
     The filter housing  43  extends substantially the length of the reservoir  45  and supports a filter screen  69  having a perforation size specification, at least in one embodiment, of  100  mesh. As a result of the reservoir  45  and filter housing  43  being spaced radially from one other, a circular well bore fluid passage  67  is formed therebetween. Preferably, the filter housing  43  is also spaced radially inward from an inside wall  13   a  of the fluid housing  13 , thereby creating a cylindrical fluid well  71  disposed between the filter housing  43  and the fluid housing  13 . As best shown in FIG. 3 b , the inside wall  13  a is equipped with a plurality of apertures or well bore inlets  73  which fluidly communicates with the filter housing  43  via fluid well  71 . When the tool assembly  11  is situated in the well bore  51 , well bore fluid  101  is allowed to flow from the well bore  51  inwardly through the inlets  73  so as to fill the fluid well  71 . 
     From the fluid well  71 , the well bore fluid  101  can pass through the filter screen  69  and into the circular well bore fluid passage  67 . 
     With particular reference to FIGS. 3 b  and  3   c , the circular well bore fluid passage  67  extends longitudinally toward the adapter  41 . The adapter  41  is formed (as necessary) with a plurality of inflation fluid passages  75  which openly communicates with circular well bore passage  67  (see also the cross sectional view of FIG.  2 ). It should be noted that, in some applications, a single inflation fluid passage may perform adequately. As best shown in FIG. 3 c , each of the fluid passages  67  or  75  is preferably equipped with a check valve  85 . The check valve  85  prevents backflow from the inflation fluid passage  75  into the circular well bore fluid passage  67 . 
     In the embodiment depicted in the drawings, a venturi device  79  is installed in the inflation fluid passage  75  downstream of the check valve  85 . The venturi device  79  is positioned such that it has a suction port  79 a in fluid communication with the fluid passageway  63  and, thus, may be operated to draw a reservoir fluid  103  from the reservoir  45 . More specifically, the pump  23  of the setting tool  15  is operable to draw suction from the inlet passageway  25 , which is in fluid communication with the inflation fluid passage  75 , and to draw well bore fluid  101  from the well bore fluid passage  67 . Upon passing of fluid through the venturi device  79 , suction is created at the suction port  79   a  to draw reservoir fluid  103  from the reservoir  45  and to introduce this reservoir fluid  103  into the well bore fluid  101  flow stream. The resulting flow stream consists of a mixture  105  of the well bore fluid  101  and the reservoir fluid. As necessary, a tortuous fluid path may be provided for the inflation fluid passage  75  and/or the pump inlet fluid passageway  25  so as to further promote and enhance mixing between the well bore fluid  101  and the reservoir fluid  103 . 
     It should be noted that, in alternative embodiments, it may not be necessary to provide the inflation fluid passage  75  with a venturi device. The fluid passages  67 ,  75 ,  63  and  25  and pump  23  may be sized and configured such that simple “Tee” connection between the fluid passage  63  and fluid passage  75  will be adequate to draw or siphon reservoir fluid flow. Further yet, in alternative embodiments, the connection between fluid passage  63  and fluid passage  75  may be located elsewhere in the supply housing  13  and/or the tool housing  31 . Applicants note, however, that the incorporation of the venturi device  79  advantageously promotes the desired fluids mixing and flow through. 
     In another aspect of the invention, the setting tool assembly  11  is configured  101  and a method is provided to employ an inflation fluid mixture  105  of well bore fluid  101  and reservoir fluid  103  which performs significantly better (in a method of inflating and/or setting an inflatable packer) than prior art fluids (e.g., formation oil, condensate, freshwater) employed as inflation fluids. 
     In particular, an inflation fluid mixture may be selected that possesses thermal properties which, for example, may be advantageous for inflatable packers used in injection or treating purposes. Furthermore, during production, the hotter temperatures of the well bore fluids in producing the zones below the packer may cause the inflation fluid in the packer to increase in volume, thereby, increasing the potential for ultimate failure (e.g., through rupturing of the packer). In these and other common applications, the setting tool assembly is exposed to a substantial differential in temperature between the time it is initially lowered into the well bore and when, for example, it reaches thermal equilibrium with the well bore environment at the packer location. If the inflation fluid is transported with the setting tool assembly, the capacity of the setting tool assembly must be sufficient to accommodate the resulting volumetric expansion of the inflation fluid. Because some high-performance fluids have a relatively high volumetric coefficient of thermal expansion, the size (e.g., length) of the tool assembly may be very long and present difficulties in handling. Conversely, if a cooler treating fluid is pumped from the surface at ambient temperature to the location of the setting tool assembly or the packer, the temperature of the packer may be caused to drop significantly. If the reduction of temperature is significant, there is a potential for the oil/condensate in the packer to shrink in volume, thereby reducing the inflation pressure and possibly causing packer failure. 
     In a method according to the present invention, a clean two-part inflation fluid is provided having improved properties advantageous in the use of inflatable packers. More specifically, an inflation fluid may be provided having a relatively low volumetric coefficient of thermal expansion, while having sufficient lubricity for pumping. In one method of the invention, the reservoir  45  is initially filled with a concentrated water soluble oil (“WS oil”). When the WS oil  103  is mixed with fresh water or formation water, the resulting mixture is an inflation fluid  105  having a lubricity conducive to pumping and having a reduced volumetric coefficient of thermal expansion. In one embodiment, a concentrated WS oil  103  is mixed at a ratio of 1 part WS oil with 10 parts well bore fluid  101 . The applicants note that such a reduced volume of reservoir fluid  103  provides the advantageous result of a reservoir having a volume that is reduced by a factor of 10 (over prior art reservoirs). For example, a 10 foot reservoir is adequate in mixing 5 gallons of inflation fluid (typical volume for a 2 ⅛″ inflatable packer in 7″ casing). It should be further noted that the present invention provides a reservoir  45  that, advantageously, expands in volume as the temperature of the reservoir fluid increases. This feature is made possible by providing a movable piston  47  which can be moved upward against the spring mechanism  49  upon an increase in the pressure inside the reservoir  45  (e.g., due to thermal expansion). 
     In one method according to the invention, the downhole pump  23  is operated to draw an inflation fluid mixture  105  consisting preferably of about five to fifteen parts of well bore fluid  101  to every part of reservoir fluid  103 , and, in some applications, more preferably, about ten parts of well bore fluid  101  to every part of reservoir fluid  103 . Of course, the mixture may be adjusted by simply adjusting the metering orifice  65  and/or adjusting the size of the fluid passages  63 ,  67  and/or the venturi device  79 . Alternatively, an injection pump may be provided in fluid communication with the fluid passage  63  and positioned to draw substantially precise amounts of inflation fluid  103  from the reservoir  45 . It should also be noted that the well bore fluid  101  is filtered through the filter screen  69  prior to entry into the fluid passages  67  to ensure the quality of the inflation fluid and to further protect the components of the setting tool assembly  11 . 
     Applicants consider water soluble fluids as suitable inflation fluids. It should be noted that the applicants have tested, in a laboratory, the use of water soluble oils, and have found them to be advantageously compatible for use with rubber products at elevated temperature. Applicants have also successfully tested these fluids in a mixture with water for use with a setting pump assembly and an inflatable plug at elevated temperatures. 
     In particular applicants have found that the inventive inflation fluid is more advantageous than fresh water as an inflatable fluid. Since fresh water has a relatively low volumetric coefficient of thermal expansion, it does not present the difficulties associated with the use of fluids as oil. However, it is also not well suited for pumping because of undesirable lubricity properties. As a result, the use of fresh water as an inflation fluid can decrease the efficiency of the system and shorten the expected life of the pump. Applicants have also found that the inventive inflation fluid is an improvement over straight well bore fluids (e.g., fluids containing brine, condensate, acids, oil, sand, completion fluids). 
     To further clarify the application of the present invention, FIGS. 5A-5D are provided to illustrate a method of locating and setting an inflatable packer  17 , according to the invention. The inflatable packer setting tool assembly  11  is connected to an electrical wire line  53  and has a diameter that is less than the well bore  51  and production tubing  91  inside the well bore  51 . Prior to entry into the well bore  51 , the reservoir  45  of the inflatable packer setting tool assembly  11  is filled with a volume of reservoir fluid  103  such as WS oil. The amount of reservoir fluid  103  is selected in view of the quantity of total fluid required to inflate the inflatable packer  17  and the desired mix ratio, but also taking into account the expected volumetric expansion of the reservoir fluid  103  in response to the elevated temperatures at the target well bore environment. Referring to FIG. 5a, the inflatable packer setting tool assembly  11  is then lowered downward into the well bore  51  using the electrical wire line  53  and, typically, to a location or depth below the production tubing  91 . As is known in the field, the tool assembly  11  may be located or positioned accurately in the well bore  51  through use of a depth measurement device incorporated in the tool assembly  11 . 
     After the tool assembly  11  is positioned at the desired depth, the pump  23  is then energized through electrical wire line  53  (see FIG. 5 b ). The operation of the pump  23  draws a pre-determined mixture  105  of the reservoir fluid  103  and the well bore fluid  101 , and delivers the mixture  105  into the inflatable packer  17  via the pump discharge passageway  35 . Upon adequate inflation of the inflatable packer  17  and attaining a pre-determined pressure, the pump energy operates to release the setting tool  15  from the then-inflated packer  17  (i.e., through a shear pin). Referring to FIG. 5 c , the setting tool  15  and the fluid housing  81  are then retrieved by raising the electric wireline  53  back to the surface. In some applications, as illustrated in FIG. 5D, the section of the well bore  51  below the inflated packer  17  is sealed by pouring a cement or other hard-drying material layer  95  above the inflated packer  17 . 
     In an alternative embodiment of the present invention, a second fluid supply housing or second reservoir may be provided to supply an inflation fluid (see e.g., FIG.  6 ), such as fresh water in addition to a reservoir  45  of WS oil  103 . This inflation fluid, i.e., fresh water, may be provided in a second reservoir  107  of the fluid supply housing  81 , or in a separate fluid supply housing  108 . The second reservoir or housing may be lowered into the well bore from the surface, but may not be mixed with the WS oil until initiation of the inflation and setting method. This is particularly desirable when one inflation fluid acts as a catalyst when mixed with the other inflation fluid, and the resulting reaction is not useful until inflation and setting of the packer. 
     Although the embodiment depicted and described herein primarily relates to the use of the inventive inflatable packer setting tool assembly with an electrical wire line and a conventional inflatable packer, the invention is also adapted for use with other common downhole equipment in similar methods of setting and/or inflating inflatable packers. Such applications and, thus alternative methods of the invention, will be apparent to those skilled in the art, upon viewing the drawings and reading the description which are provided herein 
     The foregoing description of the present invention has been presented for purposes of illustration and description. The description is not intended to limit the invention to the form disclosed herein. Consequently, variations and modifications commensurate with the above teachings, and the skill or knowledge of the relevant art, are within the scope of the invention. The embodiments described herein are further intended to explain the best modes known for practicing the invention and to enable others skilled in the art to utilize the invention in such, or other, embodiments and with various modifications required by the particular applications or uses of the present invention. It is intended that the appended claims be construed to include alternative embodiments to the extent that is permitted by the prior art.