Patent Publication Number: US-11041369-B2

Title: Brush actuator for actuating downhole tools

Description:
STATEMENT OF RELATED APPLICATIONS 
     This application depends from and claims priority to PCT/US2017/021658 entitled Brush Actuator for Actuating Downhole Tools filed on Mar. 9, 2017, which depends from and claims priority to U.S. Provisional Application No. 62/305,848 filed on Mar. 9, 2016. 
    
    
     BACKGROUND 
     Field of the Invention 
     The present invention relates to an actuator for actuating downhole tools in a cased well. More specifically, the present invention relates to a brush actuator for actuating a mechanically actuatable downhole tool that is run into a well casing to a targeted interval to perform its intended function. 
     Background of the Related Art 
     Brush tools for use in earthen wells are tools that fitted with brush elements and connected to or within a tubular string or work string. A brush tool is introduced into a well and run into a wellbore as the tubular string is extended from the surface. A plurality of brush elements of the brush tool extend radially outwardly from the brush tool to engage and abrade the interior surface of the bore of the casing. A brush tool may include a flow bore connected to the tubular string and through which fluid introduced into the tubular string at the surface can flow. Some brush tools further include jet ports through which fluid can flow from the flow bore radially outwardly to impinge onto the interior wall of the casing to assist in cleaning debris from the well casing. Debris removed from the well casing may be suspended in fluid flow and removed from the well to the surface through the tubular string/casing annulus. 
     Actuators for downhole tools are devices that enable operation of a downhole tool at a targeted interval within the well. A mechanical actuator may be operated by, for example, but not by way of limitation, varying the fluid pressure in the tubular string used to position a downhole tool in the well casing, introducing a ball or dart to sealably engage a seat or receiver in the bore of the tubular string, or by engaging a known downhole structure such as, for example, a liner top to displace an actuator and operate the tool. This latter approach has become disfavored by some operators due to concern that engaging the liner top may result in damage to the liner top or to the cement disposed to surround the liner. 
     What is needed is a mechanical actuator that can be used to actuate a downhole tool without the necessity of engaging the tool with a liner top or other structure in the well and without the need to introduce a ball or dart that obstructs flow through the tubular string. 
     BRIEF SUMMARY 
     One embodiment of the present invention provides an apparatus comprising an elongate mandrel having proximal end, a distal end and a bore therebetween, a slide member surrounding a slide portion of the mandrel, the slide member having a proximal portion, a distal portion and a brush section with a plurality of circumferentially distributed and radially outwardly extending brush elements sized to engage a well casing into which the apparatus is positioned, the slide member being movable along the portion of the mandrel between a proximal position and a distal position, an axially compressible spring element disposed intermediate the slide member and the mandrel to provide a biasing force urging the slide member towards the proximal position and a mechanically actuatable downhole tool coupled to the mandrel and operable from a run-in mode in which the slide member is in the proximal position and an actuated mode in which the slide member is moved to the distal position, wherein movement of the apparatus in a distal direction in the well casing disposes the plurality of brush elements into a trailing up mode and a force imparted to the slide member by frictional engagement of the brush elements with the well casing and the spring element together dispose the slide member in the proximal position, wherein the spring element is selected to have a spring constant that disposes the slide member in the proximal position during movement of the apparatus in a proximal direction in the well casing to dispose the brush elements in a trailing down mode in which the force resulting from frictional engagement of the brush elements with the well casing is insufficient to overcome the biasing force applied by the spring element, and wherein reversing the direction of movement of the apparatus within the well casing from movement in the distal direction to movement in the proximal direction disposes the brush elements in a transition mode providing substantially increased frictional engagement between the brush elements and the well casing that imparts a displacing force on the slide member that is sufficient to overcome the biasing force applied to the slide member by the spring element, thereby resulting in displacement of the slide member from the proximal position to the distal position to actuate the mechanically actuatable downhole tool. The transition mode of the brush elements is that critical point at which the brush elements are deformed as they are being bent by engagement of the brush elements with the well casing as the apparatus begins moving in a proximal direction after sufficient movement in a distal direction to dispose the brush elements in the trailing up mode. Embodiments of the apparatus may include a jet valve as the mechanically actuatable downhole tool, the jet valve being openable to jet fluid provided to a bore of the mandrel from the mandrel with the slide member moved to distal position on the mandrel. In one embodiment of the apparatus, a jet valve that is the actuatable downhole tool can include at least one aperture in the mandrel and at least one aperture in the slide member that is aligned with the at least one aperture of the mandrel with the slide member in the distal position. In another embodiment of the apparatus, the mechanically actuatable downhole tool comprises at least one resiliently deformable packer element that is radially outwardly expandable to a deployed mode to engage and seal between the mandrel and the well casing by movement of the slide member from the proximal position to the distal position, and the at least one resiliently deformable packer element restores to a run-in mode by movement of the slide member from the distal position to the proximal position. In one embodiment of the apparatus, the actuatable downhole tool of the apparatus comprises a plurality of axially aligned resiliently deformable packer elements. 
     In one embodiment of the apparatus, the slide member includes one of a slot and a protrusion and the mandrel includes the other of the slot and the protrusion to cooperate together to prevent unwanted rotation of the slide member on the mandrel. In one embodiment of the apparatus, the spring element is an axially compressible coil spring surrounding the mandrel. In one embodiment of the apparatus, the mandrel includes an annular recess to receive the spring element. In one embodiment of the apparatus, the brush elements are removably supported on a brush section of the slide member so that the brush elements can be replaced when worn or substituted for varying sizes of well casing. 
     One embodiment of the apparatus of the present invention includes a mandrel having a proximal end to connect to a tubular string, a distal end, a bore, a distal stop and a proximal stop, a slide member received on a slide portion of the mandrel intermediate the distal stop and the proximal stop, the slide member being reciprocatable on the slide portion of the mandrel between a proximal position, proximal to the proximal stop, and a distal position, proximal to the distal stop, the slide member having a plurality of circumferentially distributed and radially outwardly extending brush elements sized to frictionally engage a well casing in which the apparatus is moved, a spring element disposed intermediate the slide member and the mandrel to bias the slide member towards the proximal position and 
     an actuatable downhole tool connected to the mandrel, the downhole tool being actuated from a first mode to a second mode by displacement of a displaceable member of the downhole tool that is engaged and displaced by movement of the slide member from the proximal positon to the distal position, wherein moving the apparatus in a distal direction in the well casing by extending a tubular string to which the proximal end of the mandrel is connected into the well casing disposes the plurality of brush elements on the slide member in a trailing up mode due to frictional engagement between the plurality of brush elements and the well casing, and wherein moving the apparatus in a proximal direction in the well casing by withdrawing the tubular string to which the proximal end of the mandrel is connected from the well casing disposes the plurality of brush elements on the slide member in a trailing down mode due to frictional engagement between the plurality of brush elements and the well casing and wherein reversing the direction of the mandrel within the well casing from movement in a distal direction to movement in a proximal direction temporarily disposes the plurality of brush elements in a transition mode, intermediate the trailing up mode and the trailing down mode, that provides increased frictional resistance to movement of the slide member with the mandrel and in the proximal direction to impart a downwardly directed force on the slide member relative to the mandrel that is sufficient to compress the spring element and displace the slide member from the proximal position to the distal position to displace the displaceable member of the downhole tool to actuate the downhole tool from a first mode to a second mode. In one embodiment of the apparatus, the actuatable downhole tool is connected to the distal end of the mandrel. In another embodiment of the apparatus of the present invention the actuatable downhole tool comprises at least one resiliently deformable packer element that surrounds the mandrel wherein the at least one resiliently deformable packer element is actuatable from a first mode, with substantially no deformation, to a second mode in which the at least one resiliently deformable packer element is axially compressed and radially expanded to engage the well casing. In another embodiment of the apparatus of the present invention, the actuatable downhole tool comprises a plurality of resiliently deformable packer elements that are aligned along the mandrel. In another embodiment of the apparatus of the present invention, the downhole tool comprises at least one jet valve that is actuatable between a closed first mode and an open second mode wherein pressurized fluid provided to the bore of the mandrel escapes through the at least one jet valve in the second mode to impinge on the well casing. In one embodiment of the apparatus of the present invention, the downhole tool comprises a plurality of circumferentially distributed jet valves. In one embodiment of the apparatus of the present invention, the slide member includes one of a slot and a protrusion and the mandrel includes the other of a slot and a groove to together cooperate to prevent rotation of the slide member on the mandrel. In one embodiment of the apparatus of the present invention, the spring element disposed intermediate the mandrel and the slide member is a coil spring having a bore to surround the mandrel. 
     One embodiment of the apparatus of the present invention comprises a slide member reciprocatable between a proximal position and a distal position along a slide portion of a mandrel and having a plurality of brush elements thereon, a spring element disposed intermediate the slide member and the mandrel to bias the slide portion to the proximal position and an actuatable downhole tool connected to the mandrel and operable by movement of the slide member from the proximal position to the distal position wherein disposing the brush elements in a transition mode intermediate a trailing up mode and a trailing down mode by reversing the direction of movement of the apparatus within a well casing frictionally engaged by the brush elements provides sufficient displacing force to the slide member to overcome the spring element and move the slide member to the distal position to actuate the actuatable downhole tool. 
     Embodiments of the apparatus of the present invention can include a variety of actuatable downhole tools. The embodiments of the apparatus disclosed herein is not to be limiting of the adaptation of the brush actuator included in each of the disclosed embodiments to operate other embodiments of the apparatus having other actuatable downhole tools. The brush actuator of embodiments of the apparatus of the present invention presented and disclosed herein can be used with many other and different types of actuatable downhole tools. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         FIG. 1  is an illustration of a portion of a slide member of an embodiment of the apparatus of the present invention having a brush section on which a plurality of brush elements are supported in a trailing up mode. 
         FIG. 2  is an illustration of the portion of the slide member of  FIG. 1  with the brush elements supported in a trailing down mode. 
         FIG. 3  is an illustration of the brush section  20  of the slide member  30  of  FIGS. 1 and 2  in a transition mode, meaning that the brush elements are in a transition mode that is intermediate the trailing up and the trailing down modes illustrated in  FIGS. 1 and 2 , respectively. 
         FIG. 4  is a sectioned elevational view of an embodiment of an apparatus including an actuatable downhole tool that can be actuated using a brush actuator in the manner illustrated in  FIGS. 1-3 . 
         FIG. 5  is the sectioned elevational view of the apparatus of  FIG. 4  after the apparatus is manipulated to actuate the downhole jetting tool to which the brush actuator is connected. 
         FIG. 6  is a perspective view of the embodiment of the apparatus of  FIG. 4 . 
         FIG. 7  is a perspective view of the apparatus of  FIG. 6  with the slide member illustrated as transparent to reveal the spring element disposed intermediate the mandrel and the slide member to bias the slide member and the brush section thereof towards the proximal position on the apparatus. 
         FIG. 8  is a partially sectioned elevational view of an embodiment of an apparatus of the present invention having a mandrel with a proximal end, a distal end and a bore extending therethrough. 
         FIG. 9  is the partially sectioned view of the embodiment of the apparatus of  FIG. 8  after the slide member is displaced downwardly relative to the mandrel by disposing the brush elements into engagement with a well casing (not shown) and by disposing the brush elements in the transition mode to displace the slide member (see  FIG. 3 ). 
         FIG. 10  is a perspective view of a section of a perforating gun cover having a plurality of ports therein. 
         FIG. 11  is a perspective view of a perforating gun having the perforating gun cover of  FIG. 10  in the detonation mode to allow the unfouled explosive chemical charge to detonate and blast perforations into the surrounding formation. 
     
    
    
     DETAILED DESCRIPTION 
       FIGS. 1-3  are free body diagrams illustrating the modes in which the brush elements  22  of the apparatus  10  may be disposed during use embodiments of the apparatus  10  of the present invention and the manner in which the brush element modes can be manipulated to operate the apparatus  10  in a downhole cased environment. It will be understood after the discussion of the various modes in which the brush elements  22  can be disposed that embodiments of the apparatus  10  of the present invention can be manipulated in a manner that enables the operator to control and/or operate the apparatus  10  (not shown in  FIGS. 1-3 ). The length of the arrows  81 ,  82 ,  83  and  84  in  FIGS. 1-3  indicate the magnitude of the force applied to the slide member  30  by a spring element  40  (spring element  40  not shown in  FIGS. 1-3 ) that biases the slide member  30  towards a proximal position, the magnitude of the force applied to the slide member  30  by the frictional engagement of the brush elements  22  with the casing  99  with the brush elements  22  in a trailing up mode, the magnitude of the force applied by the frictional engagement of the brush elements  22  with the casing  99  with the brush elements  22  in a trailing down mode and the magnitude of the force applied by the frictional engagement of the brush elements  22  with the casing  99  with the brush elements  22  in a transition mode, respectively. It will be understood that the force applied to the slide member  30  by the spring element  40 , as indicated by arrow  81 , is the same in each of the trailing up, trailing down and transition modes in which the brush elements  22  may be disposed and only the force of the frictional engagement of the brush elements  22  with the casing  99  changes in direction or magnitude, as indicated by the arrows  82 ,  83  and  84 . 
       FIG. 1  is an illustration of a portion of a slide member  30  of an embodiment of the apparatus  10  of the present invention having a brush section  20  on which a plurality of brush elements  22  are supported in a trailing up mode. The trailing up mode means that the brush elements  22  are in a trailing position as the apparatus  10  (not shown) moves downwardly within the casing  99  in the direction of arrow  92 . As the apparatus  10  moves in the direction of arrow  92 , the casing  99  imparts an upwardly directed frictional drag force on the brush elements  22  that are supported on the brush section  20  of the slide member  30 . The frictional drag force is transferred to the brush section  20  and to the slide member  30  to which the brush section  20  is connected to impart an upwardly directed force indicated by arrow  82  on the brush section  20  and the slide member  30 . The frictional drag force imparted to the brush section  20  and the slide member  30  of the apparatus  10  (not shown) indicated by the arrow  82  is in the same direction as a force applied by a spring element  40  (not shown) of the apparatus  10  and indicated by arrow  81 .  FIG. 1  illustrates that, when the brush elements  22  are disposed in the trailing up mode, the resulting force applied to the brush section  20  and the connected slide member  30  as a result of the movement of the apparatus  10  in the downwardly direction indicated by the arrow  92  complements the force applied by the spring element  40  (not shown in  FIG. 1 ). The result is that the slide member  30  remains firmly in a proximal position on the apparatus  10 , and that an actuatable downhole tool (not shown in  FIG. 1 ) that is part of the apparatus  10  remains unactuated. 
       FIG. 2  is an illustration of the portion of the slide member  30  of  FIG. 1  with the brush elements  22  supported in a trailing down mode. The trailing down mode means that the brush elements  22  are in a trailing position as the apparatus  10  (not shown) moves upwardly within the casing  99  in the direction of arrow  94 . As the apparatus  10  moves in the direction of arrow  94 , the casing  99  imparts a downwardly directed frictional drag force on the brush elements  22  that are supported on the brush section  20  of the slide member  30 . The frictional drag force imparted to the brush section  20  and the slide member  30  of the apparatus  10  (not shown) indicated by the arrow  83  is in the opposite direction from the force applied by a spring element  40  (not shown) of the apparatus  10  and indicated by arrow  81 .  FIG. 2  illustrates that, when the brush elements  22  are disposed in the trailing down mode, the resulting force applied to the brush section  20  and the connected slide member  30  as a result of the movement of the apparatus  10  in the upwardly direction indicated by the arrow  94  opposes the force applied by the spring element  40  (not shown in  FIG. 1 ), but the force applied to the brush section  20  and the connected slide member  30  as a result of the movement of the apparatus  10  in the upwardly direction indicated by the arrow  94  is less in magnitude than the opposing force applied to the slide member  30  by the spring element  40  (not shown). The result is that the slide member  30  remains in the proximal position on the apparatus  10 , and that an actuatable downhole tool (not shown in  FIG. 2 ) that is part of the apparatus  10  remains unactuated. 
       FIG. 3  is an illustration of the brush section  20  of the slide member  30  of  FIGS. 1 and 2  in a transition mode, meaning that the brush elements  22  are in a transition mode that is intermediate the trailing up and the trailing down modes illustrated in  FIGS. 1 and 2 , respectively. The transition mode of the brush elements  22  illustrated in  FIG. 3  may be described as an intermediate mode in which the brush elements  22  are disposed in a bind. The transition mode of the brush elements  22  is achieved by first moving the apparatus  10  downwardly in the direction indicated by the arrow  95  to dispose the brush elements  22  in a trailing up mode (illustrated in  FIG. 1 ) and by then reversing the movement through a very small interval of upwardly movement of the apparatus  10  in the direction indicated by the arrow  96  to dispose the brush elements  22  in the transition mode illustrated in  FIG. 3 . It will be noted that the arrow  95  is long to illustrate that the downwardly directed movement to dispose the brush elements  22  in the trailing up mode is a relatively long movement and to illustrate that the upwardly directed movement needed to dispose the brush elements  22  in the transition mode is a relatively short interval. It will be understood that the actual interval over which the apparatus  10  must be moved upwardly (after the brush elements  22  are first disposed in the trailing up mode by downward movement) to dispose the brush elements  22  in the transition mode is determined by several factors including, but not limited to, the diameter of the casing  99 , the length, gauge and stiffness of the brush elements  22 , the diameter of the brush section  20  of the slide member  30  and the roughness (or smoothness) of the casing  99 . In the transition mode illustrated in  FIG. 3 , the frictional engagement between the brush elements  22  and the casing  99  results a downwardly directed displacing force on the brush section  20  and the slide member  30  to which the brush section  20  is connected. The downwardly directed displacing force imparted to the slide member  30 , indicated by arrow  84 , is greater in magnitude than the upwardly directed force imparted to the slide member  30  by the spring element  40  (not shown in  FIG. 3 ) as indicated by arrow  81 . The result is that the slide member  30  is displaced from the proximal position (illustrated in  FIG. 4 ) to the distal position (illustrated in  FIG. 5 ) on the apparatus  10 . This transition mode illustrated in  FIG. 3  enables an apparatus  10  having a brush actuator that includes the brush section  20 , slide member  30  and brush elements  22  as indicated in  FIGS. 1-3  to be used to selectively and repeatedly actuate an actuatable downhole tool, as discussed in further detail below. 
     Before leaving  FIG. 3 , it is important to note that the brush elements  22  can be removed from the transition mode illustrated in  FIG. 3  to restore the slide member  30  to the proximal position shown in  FIG. 4  by movement of the apparatus  10  upwardly within the casing  99  thereby causing the brush elements  22  to leave the transition mode and to enter the trailing down mode illustrated in  FIG. 1 , by movement of the apparatus  10  downwardly within the casing  99  thereby causing the brush elements  22  to leave the transition mode and to enter the trailing up mode illustrated in  FIG. 2 , or by rotation of the apparatus  10  within the casing  99 , either clockwise or counterclockwise, to cause the brush elements  22  to enter into one of two possible circumferentially trailing modes. Any of these actions will cause the brush elements  22  to leave the transition mode and the force applied by the spring element  40  to the slide member  30  will restore the slide member  30  to a proximal position on the apparatus  10 . Given the conventional direction of threads used in oilfield tubulars, rotation of the tubular string that is used to position and to move the apparatus  10  within the casing  99 , a clockwise rotation is the preferred rotation for removing the brush elements  22  from the transition mode and for restoring the apparatus  10  from the actuated mode to the run-in mode. 
       FIG. 4  is a sectioned elevational view of an embodiment of an apparatus  10  including an actuatable downhole tool that can be actuated using a brush actuator in the manner illustrated in  FIGS. 1-3 .  FIG. 5  is the sectioned elevational view of the apparatus  10  of  FIG. 4  after the apparatus  10  is manipulated to actuate the downhole jetting tool to which the brush actuator is connected. Although the embodiment of the apparatus  10  of the present invention in  FIG. 4  is not shown disposed within a casing  99 , the brush elements  22  on the slide member  30  of the apparatus  10  may, when disposed within the casing  99 , comform to the illustrations of either of  FIGS. 1 and 2  which demonstrate the trailing up and trailing down modes, respectively. In the embodiment of the apparatus  10  of  FIG. 4 , the actuatable downhole tool comprises a jet tool having a jet valve that can be opened to jet high velocity streams of a fluid, such as water or solvents, onto the casing  99  (not shown in  FIG. 4 ) to clean the casing  99  or to clean out clogged or caked perforations or other downhole structures. 
     The embodiment of the apparatus  10  of  FIG. 4  includes a tubular mandrel  14  having a proximal end  12  and a distal end  18 , a slide member  30  received to surround the mandrel  14  and movable between a proximal position, illustrated in  FIG. 4 , and a distal position illustrated in  FIG. 5 . The slide member  30  of the apparatus  10  of  FIG. 4  includes a brush section  20  on which a plurality of brush elements  22  are radially outwardly supported, a proximal end  25  and a distal end  26 . The brush elements  22  may be bundles of bristles  23  that are bound together in groups of bristles  23  to form a brush element  22 , The bristles  23  may comprise stiff steel wires, each having a common length and being supported on the brush section  20  of the slide member  30  to extend radially outwardly from the brush section  20  of the slide member  30  to engage and abrade the casing  99  (not shown in  FIG. 4 —see  FIGS. 1-3 ). The mandrel  14  of the apparatus  10  of  FIG. 4  further includes a distal stop  19 , a bore  78 , a proximal stop  21  and a slide section  31  disposed intermediate the proximal stop  21  and the distal stop  19  along which the slide member  30  reciprocates as it moves from a run-in mode illustrated in  FIG. 4  to an actuated mode illustrated in  FIG. 5 . A spring element  40  is disposed intermediate the slide member  30  and the mandrel  14  to bias the slide member  30  away from the actuated mode illustrated in  FIG. 5  and towards the run-in mode illustrated in  FIG. 4 . The distal end  26  of the slide member  30  may engage the distal stop  19  on the mandrel  14  with the slide member  30  disposed in the distal position illustrated in  FIG. 5  and the proximal end  25  of the slide member  30  may engage the proximal stop  21  of the mandrel  14  with the slide member  30  of the apparatus  10  disposed in the proximal position illustrated in  FIG. 4 . The mandrel  14  may include a stabilizer  27  along an outer surface  16  of the mandrel  14  to isolate engagement between the slide member  30  and the casing  99  (not shown in  FIGS. 4 and 5 ) to the brush elements  22  supported on the brush section  20  of the slide member  30 . 
     The slide member  30  of the apparatus  10  of  FIG. 4  further includes a plurality of circumferentially distributed apertures  46 . The mandrel  14  of the apparatus  10  of  FIG. 4  includes a plurality of circumferentially distributed apertures  50 . In the run-in mode of the apparatus  10  indicated in  FIG. 4 , the slide member  30  is in the proximal position and the plurality of apertures  46  in the slide member  30  are not aligned with the plurality of apertures  50  in the mandrel  14 . No fluid can be jetted through the plurality of apertures  46  of the slide member  30  or through the apertures  50  of the mandrel  14  in the run-in mode of the apparatus  10  illustrated in  FIG. 4 . 
       FIG. 5  is the perspective view of the apparatus  10  of  FIG. 4  after the apparatus  10  is manipulated within a casing  99  (not shown in  FIG. 5 —see  FIG. 3 ) to actuate the downhole jetting tool to which the brush actuator is connected. Although the embodiment of the apparatus  10  of the present invention in  FIG. 5  is not shown disposed within a casing  99 , the brush elements  22  on the slide member  30  of the apparatus  10  may, when disposed within the casing  99 , comform to the illustration of  FIG. 3  which demonstrates the transition mode of the brush elements  22  in which the actuatable downhole tool of the apparatus  10  is actuated.  FIG. 5  illustrates the alignment of the plurality of apertures  46  in the downwardly displaced slide member  30  with the corresponding plurality of apertures  50  of the mandrel  14  to open the jetting valve formed by the plurality of apertures  46  of the slide member  30  and plurality of apertures  50  of the mandrel  14 . A jet spray  74  is produced at each set of aligned apertures  46  and  50  to impinge upon the casing  99  (not shown). 
       FIG. 6  is a perspective view of the embodiment of the apparatus  10  of  FIG. 4 . The spring element  40  that is disposed intermediate the slide member  30  and the mandrel  14  cannot be seen in  FIG. 6 . The stabilizer  15  is adapted to provide stand-off from the casing  99  (not shown) while permitting annular flow. The brush elements  22  are shown in an optional arrangement in which each brush element  22  is circumferentially offset from an adjacent brush element  22 . The slide section  31  of exterior surface  16  of the mandrel  14 , along which the slide member  30  can be moved, is shown in  FIG. 6 . A protrusion  56  is shown as being fixed to the mandrel  14  and received within a slot  44  in the slide member  30  to prevent rotation of the slide member  30  on the mandrel  14 . It will be understood that the slide member  30  can move axially along the mandrel  14  within the slide section  31  as permitted by the slot  44  alignment, but the slide member  30  is restrained from rotation on the mandrel  14  by the slot  44  and protrusion  56 . Actuation of the embodiment of the apparatus  10  of  FIG. 6  moves the slide member  30  away from the proximal end  12  of the mandrel  14  and towards the distal end  18  of the mandrel  14  in the direction of arrow  32 . 
       FIG. 7  is a perspective view of the apparatus  10  of  FIG. 6  with the slide member  30  illustrated as transparent to reveal the spring element  40  disposed intermediate the mandrel  14  and the slide member  30  to bias the slide member  30  and the brush section  20  thereof towards the proximal position on the apparatus  10 .  FIG. 7  illustrates a distal end  17  of the slide member  30  that engages the stop wall  17  of the stabilizer  15  upon displacement of the slide member  30  to the distal position. In  FIG. 2 , it can be seen that the slide member  30  is in the proximal position and there is an exposed portion of the mandrel  33  between the distal end  34  of the slide member  30  and the stop wall  17  of the stabilizer  15 . 
       FIGS. 8 and 9  illustrate an embodiment of the apparatus  10  comprising a deployable packer element. These drawings illustrate the adaptability of the apparatus  10  of the present invention for use with various actuatable downhole tools. 
       FIG. 8  is a partially sectioned elevational view of an embodiment of an apparatus  10  of the present invention having a mandrel  14  with a proximal end  12 , a distal end  64  and a bore  13  extending therethrough. The apparatus  10  of  FIG. 8  further includes a slide member  30  reciprocatably received to surround the mandrel  14 , the slide member  30  having a brush section  20  and a plurality of circumferentially distributed brush elements  22  supported on the brush section  20  of the slide member  30  to extend radially outwardly from the slide member  30  to engage a casing  99  (not shown in  FIG. 8 ) into which the apparatus  10  may be disposed. The proximal end  12  of the mandrel  14  includes threads  77  for coupling the apparatus  10  to a tubular string (not shown) that can be used to position and move the apparatus  10  within a cased well. The apparatus  10  further includes a spring element  40  disposed intermediate the slide member  30  and the mandrel  14  to bias the slide member  30  towards a proximal position on the mandrel  14  illustrated in  FIG. 8 . The spring element  40  of the apparatus  10  of  FIG. 8  is illustrated as being received into an annular recess  33  formed in the mandrel  14 . 
     The apparatus  10  of  FIG. 8  further includes a plurality of resiliently compressible packer elements  61  that are coupled to surround the mandrel  14  intermediate the proximal end  12  and the distal end  64 . The packer elements  61  are axially compressible to produce a radially outwardly expanded configuration that will be discussed in connection with  FIG. 9 . In the embodiment of the apparatus  10  of  FIG. 8 , the plurality of packer elements  61  are disposed on the mandrel  14  intermediate an end ring  62  and the distal end  64  of the mandrel  14 . The end ring  62  is engaged by the distal end  26  of the slide member  30 . In the embodiment of the apparatus  10  of  FIG. 8 , there are three packer elements  61 , each separated from at least one adjacent packer element  61  by an intermediate ring  63 . 
       FIG. 9  is the partially sectioned view of the embodiment of the apparatus  10  of  FIG. 8  after the slide member  30  is displaced downwardly relative to the mandrel  14  by disposing the brush elements  22  into engagement with a well casing  99  (not shown) and by disposing the brush elements  22  in the transition mode to displace the slide member  30  (see  FIG. 3 ). The end ring  62  is displaced downwardly by the slide member  30  to axially compress and to radially outwardly expand the plurality of packer elements  61  to engage and seal with the casing  99  (not shown). 
     In some embodiments of the apparatus  10  of the present invention, the seal(s) between the radially expanded plurality of packer elements  61  and the casing  99  (not shown) into which the apparatus  10  is disposed enables a section of casing  99  below the plurality of packer elements  61  to be pressure tested by providing pressurized fluid into the tubular string (not shown) connected to the proximal end  12  of the mandrel  14  of the apparatus  10 . Embodiments of the apparatus  10  of the present invention may also be used to pressure test by providing pressurized fluid into the annulus (not shown) radially intermediate the tubular string (not shown) and the casing  99  (not shown) of the well. Embodiments of the apparatus of the present invention  10  may be used to ensure that well treatment fluids such as, for example, acids, can be injected through targeted casing  99  perforations and into subsurface geologic formations for increased production through stimulation. It will be understood that embodiments of the apparatus  10  of the present invention can be used in other ways to test, stimulate or service wells. 
       FIG. 10  is a perspective view of a section of a perforating gun cover  89  having a plurality of ports  90 A therein. The perforating gun cover  89  can be movably disposed on a perforating gun (not shown in  FIG. 10 ) having a plurality of explosive chemical charges  90 B (not shown in  FIG. 10 ) along its length, the perforating gun cover  89  being movable from a run-in mode, in which the explosive chemical charges  90 B along the perforating gun are covered and protected against fouling by well fluids, to a detonation mode in which the explosive charges along the perforating gun are exposed for detonation. 
       FIG. 11  is a perspective view of a perforating gun  102  having the perforating gun cover  89  of  FIG. 10  in the detonation mode to allow the unfouled explosive chemical charges  90 B to detonate and blast perforations  98  into the surrounding formation. 
     It will be understood that the spring element  40 , illustrated in the appended figures as a coil spring, may be other types of spring elements including, but not limited to, a spring element having a volume of a compressible gas or elastically deformable elements. It will be understood that the slide member  30  and the support collar  20  may, in some embodiments, be connected one to the other and, in other embodiments, the slide member  30  and the support collar  20  may be integral one with the other. The brush elements  22  of the brush tool  10  are preferably releasably coupled to the support collar  20  of the brush tool  10 , but may also be integrally connected. 
     The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, components and/or groups, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. The terms “preferably,” “preferred,” “prefer,” “optionally,” “may,” and similar terms are used to indicate that an item, condition or step being referred to is an optional (not required) feature of the invention. 
     The corresponding structures, materials, acts, and equivalents of all means or steps plus function elements in the claims below are intended to include any structure, material, or act for performing the function in combination with other claimed elements as specifically claimed. The description of the present invention has been presented for purposes of illustration and description, but it is not intended to be exhaustive or limited to the invention in the form disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the invention. The embodiment was chosen and described in order to best explain the principles of the invention and the practical application, and to enable others of ordinary skill in the art to understand the invention for various embodiments with various modifications as are suited to the particular use contemplated.