Patent Publication Number: US-8967268-B2

Title: Setting subterranean tools with flow generated shock wave

Description:
FIELD OF THE INVENTION 
     The field of the invention is a setting mechanism for subterranean tools and more particularly a mechanism to produce a flow induced pressure wave that is sufficient to set the tool. 
     BACKGROUND OF THE INVENTION 
     Tools located in very deep wells frequently need pressure levels for setting that can be beyond the capabilities of surface pumping equipment. One way to set such tools is to develop a boost force in the form of a pressure surge to get the internal pressure in the tool to a level where the tool can be set. 
     One attempt at doing this is illustrated in U.S. Pat. No. 7,870,895 where initial movement of the packer setting mechanism triggers either a chemical reaction that generates gas pressure or a setting off of explosive to get a pressure surge to set the packer. These two sources can be an assist or the sole driving force for setting the packer with a pressure sensitive piston. Generating the pressure surge with chemicals or explosives creates increased cost as well as safety issues and transportation issues to the well site. 
     What is needed is a simpler and cheaper way to generate a pressure surge to set a subterranean tool and the present invention addresses this issue. The kinetic energy of flowing well fluids are deployed and a hammer effect is created by abrupt interruption of circulating fluid while still leaving a flow channel open to reach an actuating piston for the tool. The fluid hammer effect that is created provides sufficient pressure to set the tool. The hammer effect is created with either a rapid increase in flow to close a circulation port or a dropped object on a seat that isolates a circulation port while leaving access open to an actuation piston for the tool. In the preferred embodiment the tool is a pressure set packer but other types of tools are contemplated. Those skilled in the art will more readily appreciate the details of the invention from the attached description and the associated drawings while recognizing that the full scope of the invention is to be found from the appended claims. 
     SUMMARY OF THE INVENTION 
     A circulation sub is provided that has a ball seat and a circulation port that is closed when a ball is landed on the seat. An axial passage directs the pressure surge created with the landing of the ball on the seat to the port with the actuation piston for the tool. The surge in pressure operates the actuation piston to set the tool, which is preferably a packer. In an alternative embodiment raising the circulation rate through a constriction in a circulation sub breaks a shear device and allows the restriction to shift to cover a circulation port. The pressure surge that ensues continues through the restriction to the actuating piston for the tool to set the tool. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS. 1   a  and  1   b  illustrate the embodiment where the seating of a ball on a seat creates the pressure wave to the tool actuation piston respectively in the run in and the set positions; and 
         FIGS. 2   a  and  2   b  use an increase in flow to create the pressure wave to the tool actuation piston and respectively show the run in and the set positions: 
         FIGS. 3   a - 3   b  are an alternative embodiment to  FIGS. 2   a - 2   b  showing a collet as a retainer rather than a shear pin; 
         FIGS. 4   a - 4   b  are an alternative embodiment illustrating a spring loaded ball that seats with pressure to isolate a lateral port; 
         FIG. 5  is a detailed view of the boost piston shown in  FIG. 2   a  showing a lateral opening to avoid liquid lock of the boost piston; 
         FIGS. 6   a - 6   b  are another alternative embodiment where the circulation ports are closed with a spring-loaded ported sleeve. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       FIG. 1  illustrates a wellbore  10  in a schematic manner so that what is represented could be cased or open hole. The tool  12  is illustrated as a packer for isolation service but other tools are contemplated and item  12  is intended to be representative of any such tool or tools. Applied pressure in port  14  enters annular space  16  which is sealed by piston  18  and its outer seal  20  and inner seal  22 . As shown in  FIG. 1   b  axial movement of the piston  18  sets the packer  12 . 
     Connected to the top of the packer mandrel  42  is a circulation sub  26 . A ball seat  28  is located above lateral port  30  such that without ball  32  landed in seat  28  circulation, down a dedicated path to port  30 , represented by arrow  34  up the annular space  36  and to the surface is possible. Axial passage  38  remains open even when ball  32  lands in seat  28 . Passage  38  leads into passage  40  in mandrel  42  and down to port  14 . As shown in  FIG. 1   b  when the ball  32  lands on seat  28  the lateral port  30  is abruptly closed off. This creates a pressure surge akin to a water hammer effect that propagates through passage  38  into passage  40  and then to port  14  to push the piston  18  and set the packer  12 . 
       FIGS. 2   a  and  2   b  also have a lateral port  30  but instead of a ball seat as in  FIG. 1  there is now in its place a sleeve  50 , or upset having a taper  52  leading to a through passage  54 . A shear pin  56  holds the sleeve  50  in place so that circulation represented by arrow  34  can take place. When flow is increased as represented by arrows the pressure differential across the sleeve  50  goes up to a point where the shear pin  56  breaks and the sleeve  50  shifts to close ports  30 . This results in a pressure shock wave being developed as represented by arrow  60  and the packer  12  sets in the same way as described above for  FIG. 1 . 
       FIGS. 3   a - 3   b  show that initially the collet  71  is latched in groove  72  when the ports  30  are open and when flow is increases to increase the net force on sleeve  50 , the sleeve is shifted to block ports  30  while allowing through flow to a tool such as a packer  12  for setting using the shock wave that is created. In the blocked position of ports  30  the collet  71  is latched into groove  74  as shown in  FIG. 3   a . As an alternative a snap ring can be used to latch into grooves  72  and  74 . The sleeve  50  can be reset for another cycle with reverse flow in the direction opposite arrow  34  that will force up the sleeve  50  until the groove  72  is re-latched. 
       FIGS. 4   a - 4   b  are a variation of the  FIGS. 1   a - 1   b  design where instead of dropping a ball  32  on a seat  28  there is an elongated member  80  biased by a spring  82  to keep ports  30  open until flow is increased to seat the ball segment  84  on seat  86  to isolate the ports  30  while leaving passage  38  open to set a tool such as a packer  12 . Reducing the flow allows spring  82  to bias ball  84  away from seat  86 . 
       FIG. 5  shows in greater detail the boost piston  70  shown in  FIG. 2   a . It adds a vent passage  90  to allow the piston  70  to move without getting liquid locked. The boost ratio is the ration of the area of surface  92  divided by the area of surface  94 . One or more pistons  70  can be connected in a variety of configurations to further enhance the boost force. Arrangements in series or parallel are contemplated. 
       FIGS. 6   a - 6   b  are an alternative embodiment to  FIGS. 1   a - 1   b  where instead of dropping a ball  32  on a seat  28  flow is increased to bias a sleeve against a spring  101  force and seat the sleeve in a manner that the ports  102  in the sleeve are isolated from the housing ports  30  while still leaving a dedicated passage  38  open to the tool such as packer  12 . When flow is reduced the spring biases the ported sleeve  100  so that the openings of the ported sleeve again can communicate with the housing ports  30  which in effect resets the tool for another cycle if needed. 
     Those skilled in the art will appreciate that the use of the kinetic energy of the circulating fluid is employed in the different configurations described in the drawings to create a hammer effect with the resulting pressure spike being conducted to the setting port of the tool for use in setting the tool. A rupture disc can be placed in the tool port that breaks under the force of the hammer effect. The spike is over and above the static pressure delivered by the surface pumping equipment. In each case there is a single moving part, either the ball  32  or the sleeve  50 . The design is simple and cheap to build and needs no seals that can be attacked by grit in the well fluids. Although a single passage  38  is shown, multiple passages can be used. The tools actuated can be anchors, fishing tools, vibratory tools, jars, spears and grapples to name a few examples. 
     The creation of the hammer effect can also be combined with a piston or pistons in passage  40  that multiply the hammer effect by having a larger dimension to receive the hammer effect and a smaller dimension on an opposite side so that the hammer effect can be multiplied by the ratio of the diameters of the piston on opposed sides. To do this passage  40  would have two different dimensions to accommodate the two piston diameters of this booster piston that responds to the created hammer effect. Piston  70  is shown schematically in  FIG. 2   a  to illustrate this optional concept. On the other hand the intensity of the pulse can also be moderated by a relief valve, not shown, that allows flow out of the housing and into the surrounding annulus to control the extent of the hammer effect on the tool to be set. A check valve could be installed to the tubing string in the flow path upstream from the circulation sub  26  and trap the pressure spike and maintain the setting pressure for a longer period of time. The tubing string design or check valve could have internal features to allow the trapped pressure to eventually bleed off if desired. Preferably the tubing string inner diameter should be substantially constant from the location of the check valve to the circulation sub  26 . 
     The above description is illustrative of the preferred embodiment and many modifications may be made by those skilled in the art without departing from the invention whose scope is to be determined from the literal and equivalent scope of the claims below.