Abstract:
A hydraulic setting tool for packers capable of mechanically setting the packer and opening a valve in the packer in one trip. The tool comprises an outer sleeve and an inner mandrel coaxially disposed within the outer sleeve and adapted to move axially relative to the outer sleeve. The tool further comprises three locking mechnisms that unlock under different fluid pressure loads. Two of the locking mechanisms lock the inner mandrel to the outer sleeve in a run-in position. Once a sufficient fluid pressure has been reached to unlock both of these locking mechanisms, the inner mandrel moves upward relative to the outer sleeve to set the packer. A spring forces the inner mandrel into a third position relative to the outer sleeve, which is maintained by the third locking mechanism. This third position is used to open the packer valve.

Description:
BACKGROUND 
   The present invention relates generally to setting tools for packers and more particularly to a hydraulic setting tool for packers, which is capable of setting the packer and opening the packer valve in one trip. 
   Generally, the production efficiency of an operating oil and/or gas well decreases over time. This is due to a number of factors. In some cases, it is simply due to the fact that a reservoir containing hydrocarbons is near depletion. In many other cases, it is due to the fact that a path along which the hydrocarbons flow becomes blocked. This can occur for a number of reasons, such as production screens becoming plugged and the closing of a fracture through which the hydrocarbons flow. When this occurs, the well needs to undergo what is known in the art as a “workover.” A workover is an operation to open the path along which hydrocarbons flow. 
   During a workover, production tubing is removed from the well and workover tools are sent downhole in its place. One of the workover tools is a packer. A packer is a device placed in the region of the well that needs treatment. The packer isolates the region needing treatment from the rest of the well. Furthermore, the packer has a valve that can be opened and closed to control the flow of treatment fluid into the subterranean formation. When the workover is complete, the packer is drilled out of the well and the production tubing is inserted back into the well thereby enabling production to resume. 
   In order to install packers into the well and control the opening and closing of their valves, specialized equipment known as “setting tools” have been developed. Generally, there are two basic types of setting tools, those characterized as mechanical and those characterized as hydraulic. Both types of setting tools are attached at the end of a workstring and are operable from the surface. 
   Conventional mechanically operated setting tools require that the workstring be rotated in order to set the packer. This raises a number of problems in horizontal wells. For one, rotation of the workstring in a horizontal well can cause the workstring to break. Furthermore, rotation of the workstring at the surface may cause a delayed rotation downhole or no rotation at all. In either case, the well operator cannot be certain that the packer has been set. Drag spring mechanical setting tools have recently had the additional problem of not setting the packer when used in synthetic fluids. These drag spring mechanical setting tools do not offer enough resistance to rotate properly in the new synthetic fluids and thereby fail to set the packers. 
   Conventional hydraulic setting tools typically employ the use of a ball or plug to create the necessary fluid pressure to activate the packer. A drawback of this technique is that the ball or plug has to be removed from the workstring after the packer is set before performing additional operations. This requires recirculation of the fluid to the surface, which in turn takes time and adds expense to the operation. 
   A further drawback of conventional mechanical and hydraulic setting tools is that it typically requires at least two trips downhole with the workstring to accomplish the tasks of setting the packer, opening the packer valve and pumping the treatment fluid into the subterranean formation through the packer. The necessity of two trips to accomplish these tasks takes time and thus adds expense to the operation. 
   Furthermore, conventional setting tools are limited in that multiple setting tools are typically required to set different size packers. This is particularly problematic in offshore applications where space is limited and transporting and storing multiple setting tools on site can be a challenge. 
   SUMMARY 
   The present invention provides a hydraulic setting tool for packers, which meets the needs described above and overcome the deficiencies of the prior art. In its preferred embodiment, the hydraulic setting tool in accordance with the present invention has the ability to both set the packer and open the valve in the packer in one trip. It accomplishes this through the use of an outer sleeve and an inner mandrel coaxially disposed within the outer sleeve and adapted to move axially relative to the outer sleeve. 
   In another aspect of the present invention, the setting tool includes first means for locking the inner mandrel into a first predetermined axial position relative to the outer sleeve. This is the position in which the setting tool is “run-in” the well. Preferably, the first locking means comprises a locking ring housing disposed between the inner mandrel and the outer sleeve and is adapted to be axially movable relative to the inner mandrel and outer sleeve. The first locking means also comprises a piston pin housing attached to a housing connection, which connects the piston pin housing to the inner mandrel. It further preferably comprises a shear pin adapted to fail under a predetermined load, which temporarily secures the locking ring housing to the piston pin housing. The first locking means additionally comprises four locking lugs that are disposed between a flanged end of the locking ring housing and the inner mandrel, which locks the inner mandrel to the outer sleeve so as to make it axially immovable. 
   In another aspect of the present invention, the first locking means further comprises a shear coupling disposed between the inner mandrel and the outer sleeve wherein the shear coupling has a shoulder against which a flanged-shaped portion of the inner mandrel abuts. It further comprises a shear pin adapted to fail under a predetermined load, which temporarily secures the shear coupling to the outer sleeve thereby making the inner mandrel axially immovable relative to the outer sleeve in an upward direction. The predetermined load necessary to cause the shear pin that temporarily secures the shear coupling to the outer sleeve to fail is preferably greater than the predetermined load necessary to cause the shear pin that temporarily secures the locking ring housing to the piston pin housing to fail. The first locking means thus prevents the setting tool from prematurely setting the packer during run-in. 
   The first locking means is disengaged by pumping fluid into the setting tool until both shear pins fail. Additional fluid pressure is subsequently added to force the inner mandrel upward relative to the outer sleeve, which in turn sets the packer. 
   In yet another aspect of the present invention, the hydraulic setting tool further comprises means for biasing the inner mandrel into a second predetermined axial position relative to the outer sleeve. In this position, the setting tool is able to open the valve in the packer. Preferably, the biasing means comprises a helical spring, which at one end engages a shoulder formed in the inner mandrel and at another end engages a shoulder formed in the outer sleeve. 
   In still another aspect of the present invention, the hydraulic setting tool includes second means for locking the inner mandrel into the second predetermined axial position. The second locking means preferably comprises a locking key disposed in a groove in the outer sleeve and a spring, which forces the locking key into a groove formed in the inner mandrel when the inner mandrel is in the second predetermined axial position thereby locking the inner mandrel to the outer sleeve so as to make it axially immovable. 
   Other and further objects, features and advantages of the present invention will be readily apparent to those skilled in the art upon a reading of the description of preferred embodiments which follows. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention is better understood by reading the following description of non-limitative embodiments with reference to the attached drawings wherein like parts of each of the several figures are identified by the same referenced characters, and which are briefly described as follows: 
       FIGS. 1–3  are schematic diagrams of non-continuous portions of the upper, middle and lower sections of the hydraulic setting tool in accordance with the present invention shown in a “run-in” position. 
       FIGS. 4–6  are schematic diagrams of non-continuous portions of the upper, middle and lower sections of the hydraulic setting tool in accordance with the present invention shown in a “shear-off” position. 
       FIGS. 7–9  are schematic diagrams of non-continuous portions of the upper, middle and lower sections of the hydraulic setting tool in accordance with the present invention shown in a “stinger-locked” position. 
       FIG. 10  is an enlarged schematic diagram of that section of the hydraulic setting tool in accordance with the present invention showing the locking mechanism that locks the hydraulic setting tool in both axial directions. 
       FIG. 11  is an enlarged schematic diagram of the upper section of the hydraulic setting tool in accordance with the present invention illustrating the mechanism that locks the hydraulic setting tool in the stinger-locked position. 
       FIG. 12  is a schematic diagram showing one side of a drillable packer, which is attached at an end of the hydraulic setting tool in accordance with the present invention. 
   

   It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, as the invention may admit to other equally effective embodiments. 
   DETAILED DESCRIPTION OF THE INVENTION 
   The details of the present invention will now be discussed with reference to the figures. Turning to  FIGS. 1–3 , a setting tool in accordance with the present invention is shown generally by reference numeral  10 . Setting tool  10  comprises an outer sleeve  12  and an inner mandrel  14 . The outer sleeve  12  is formed generally of a tubular shaped steel pipe and connects at one end to a workstring (not shown). The inner mandrel  14  is also generally tubular shaped and formed of steel. The inner mandrel  14  is coaxially disposed within the outer sleeve  12  and is adapted to move in the axial direction relative to the outer sleeve  12 . A drillable packer  68  is attached to the end of the inner mandrel  14 . Although details of the setting tool  10  are discussed with reference to drillable packer  68 , it will be understood that setting tool  10  can be used with a retrievable packer, drillable and retrievable bridge plugs, and similar downhole tools. 
   Setting tool  10  further comprises a spring  16  which abuts at one end against a shoulder of the outer sleeve  12  and abuts at the other end against a shoulder against the inner mandrel  14 , as shown in  FIG. 1 . In compression, the spring  16  supplies an axial force against the inner mandrel  14  tending to move the inner mandrel  14  downward relative to the outer sleeve  12 . Spring  16  is preferably formed of steel and assumes the shape of a helical coil. Those of ordinary skill in the art will appreciate other equivalent biasing means may be employed to move the inner mandrel  14  relative to the outer sleeve  12 . 
   Setting tool  10  further comprises a bi-directional locking device referred to generally by reference numeral  18 . The bi-directional locking device  18  comprises a locking ring housing  20 , which is generally tubular shaped and coaxially disposed between an outer surface of the inner mandrel  14  and an inner surface of the outer sleeve  12 , as best seen in  FIG. 10 . Locking ring housing  20  is adapted to move axially relative to the outer sleeve  12  and the inner mandrel  14 . The locking ring housing  20  comprises an inner O-ring  22  and an outer O-ring  24 . Inner and outer O-rings  22  and  24  are preferably formed of an elastomeric material. The inner O-ring  22  seals the locking ring housing  20  against the outer surface of the inner mandrel  14  and the outer O-ring  24  seals the locking ring housing  20  against a housing connection  26 , which is disposed within outer sleeve  12 . The locking ring housing  20  divides the space between the inner mandrel  14  and the outer sleeve  12  into two chambers, an upper chamber  28  and a lower chamber  30 . Fluid is allowed to enter lower chamber  30  through ports  32  formed in the inner mandrel  14 , as shown in  FIGS. 3 and 10 . The inner and outer O-rings  22  and  24  provide a hermetic seal thereby preventing fluid from entering the upper chamber  28  through the lower chamber  30 . 
   Bi-directional locking device  18  further comprises a piston pin housing  34  disposed between the locking ring housing  20  and the housing connection  26 . Piston pin housing  34  is attached on one side to housing connection  26  and on the other side to locking ring housing  20 . The piston pin housing  34  comprises an annular recess into which a shear pin  36  is placed. The shear pin  36  temporarily attaches the piston pin housing  34  to the locking ring housing  20 . Shear pin  36  is designed to fail at a predetermined load, which corresponds to an upward fluid pressure applied to the locking ring housing  20  created by pumping fluid down hole into the lower chamber  30  through ports  32 . In one example according to the present invention, the shear pin  36  shears under a pressure of 850 psi. 
   The locking ring housing  20  further comprises flange  38  at a down hole end, which is designed to abut against a plurality of locking lugs  40 . Preferably, there are four locking lugs  40  disposed around the circumference of the inner mandrel  14 . More preferably, the locking lugs  40  are spaced equidistant around the circumference of the inner mandrel  14 , i.e., they are disposed 90° apart from one another. Locking lugs  40  are designed to abut against the flange  38  of the locking ring housing  20 , and a shoulder formed in the outer sleeve  12 , and reside in a groove in the inner mandrel  14 . Locking rings  40  act as a wedge and prevent bi-directional axial movement of the inner mandrel  14  relative to the outer sleeve  12 . 
   Setting tool  10  comprises another locking device  42 , which prevents inner mandrel  14  from moving relative to the outer sleeve  12  in a “run-in” position. The locking device  42  includes a shear coupling  44 , which is attached to the outer sleeve  12  by shear pin  46 , as shown in  FIG. 3 . The shear coupling  44  is coaxially disposed between the inner mandrel  14  and the outer sleeve  12 . It has an annular recess formed within it for threading engagement with the shear pin  46 . The shear pin  46  is designed to fail at a predetermined load, which is preferably higher than the predetermined load necessary to cause shear pin  36  to fail. In one embodiment, the shear pin  46  fails at approximately 1,200 psi. The shear coupling  44  also includes a shoulder, which is designed to abut against a flange  48  formed on an outer surface of the inner mandrel  14 . Shear coupling  44  prevents upward movement of the inner mandrel  14  relative to the outer sleeve  12 , and bi-directional movement of the packer  68  relative to the outer sleeve  12 . More specifically, it prevents the inner mandrel  14  from moving axially relative to the outer sleeve  12  in the event that the setting tool  10  is inadvertently thrust against an obstruction during run-in. It thereby prevents premature setting of the packer  68 . 
   Setting tool  10  comprises another locking device  50 , which is provided to place the setting tool  10  in a “stinger-locked” position as shown in  FIGS. 7–9 . In the stinger-locked position, the setting tool  10  is able to open a valve of the packer  68 . The locking device  50  comprises a plurality of locking keys  52 , as shown in  FIG. 5 . Preferably, eight locking keys  52  are provided around the circumference of the inner mandrel  14 . More preferably, the locking keys  52  are spaced equidistant around the circumference of the inner mandrel  14 , i.e., 45° apart from one another. The locking keys  52  are disposed between inner mandrel  14  and the outer sleeve  12 , as shown in  FIG. 11 . The locking keys  52  are generally rectangular-shaped, and generally radius-shaped in cross section. The locking keys  52  are housed within a recess in the inner surface of the outer sleeve  12  and are forced into engagement with the outer surface of the inner mandrel  14  by a retaining spring  54 . A recessed groove  56  is formed along the outer surface of the inner mandrel  14  and is designed to accommodate the eight locking keys  52 . In particular, the groove  56  is approximately equal to or slightly larger in length and width to the locking keys  52 . The retaining spring  54  forces the locking keys  52  into the groove  56  when the groove  56  is directly aligned under the locking keys  52 , which occurs in the stinger-locked position. Inner mandrel  14  is placed in the stinger-locked position by the spring  16 , as will be described in more detail below. 
   The operation of the setting tool  10  in accordance with the present invention will now be described. In operation, the setting tool  10  (which is attached at one end to the workstring and has hanging from it at the other end packer  68 ) is placed into the wellbore, which is typically filled with fluid. A fill-in valve, which is part of the workstring (not shown) is provided to allow the fluid within the well to flow into the inside of the workstring and setting tool  10 . The fill-in valve is configured such that once the desired depth is achieved the fill-in valve closes. The fill-in valve employs a sleeve, which is held in place by shear pins, which shear once the desired depth is reached. The shearing of the shear pins causes the sleeve to slide over input ports, which in turn closes the flow of fluid into the workstring and setting tool  10 . As those of ordinary skill in the art will appreciate, other mechanisms may be employed to fill the workstring and setting tool  10  while running in the wellbore. 
   The configuration shown in  FIGS. 1–3  is the configuration in which the setting tool  10  is placed into the wellbore. This is known as the run-in position. In this position, spring  16  is partially compressed and therefore is run-in in a partially pre-loaded condition. Also, in this position, the bi-directional locking device  18  is placed in the locked position and thereby bi-directionally locks inner mandrel  14  to the outer sleeve  12 . Furthermore, in the run-in position, the locking device  42  is also placed in the locked position, which precludes the inner mandrel  14  from moving upward relative to the outer sleeve  12 . 
   Once the setting tool  10  has reached its desired position within the well, i.e., the position wherein it can set the packer  68 , the workstring ceases to be lowered into the well. As previously mentioned, the shear pins  36  and shear pins  46  engage locking devices  18  and  42 , respectively, which in turn prevent the inner mandrel  14  from moving axially in either direction relative to the outer sleeve  12 . This pre-locked position prevents such movement and therefore premature setting of the packer  68  in the event that any unexpected movement occurs downhole. 
   In order to set the packer  68 , fluid is pumped down into the setting tool  10  through the inside of the inner mandrel  14 . The fluid exits ports  32  and in turn enters lower chamber  30 . As the pressure builds, it applies an upward force onto the locking ring housing  20 . The inner and outer O-rings  22  and  24  prevent the fluid from entering into the upper chamber  28 . Once sufficient pressure is reached, the shear pin  36  fails forcing the locking ring housing  20  to push upward, which in turn moves the flange  38  out of engagement with the locking lugs  40 . This in turn disengages the bi-directional locking device  18 , which but for the engagement of the locking device  42  would otherwise allow the inner mandrel  14  to move axially relative to the outer sleeve  12 . In order to disengage the locking device  42 , fluid is continued to be pumped down the workstring to the setting tool  10 . Additional pressure is applied until the shear pin  46  ultimately fails. 
   As pointed out above, the full pressure required to shear pin  46  is higher than that necessary to shear the shear pins  36 . Once the shear pin  46  has failed, the inner mandrel  14  is free to move axially in either direction relative to the outer sleeve  12 . The fluid pressure forces the inner mandrel  14  upward. As the inner mandrel  14  is forced upward, it compresses the spring  16  as shown in  FIG. 4 . It is this upward movement of the setting tool  10  which sets the packer  68 . As shown in  FIG. 12 , as the inner mandrel  14  is pushed upward, wedges  60  press against slips  62  and force them into an interference fit engagement with the inner wall of casing string  64 . Flange tips formed on the slip  62  compress against an elastomeric membrane  66  forcing it into engagement with the inner wall of the casing string  64  in turn causing it to form a hermetic seal between the inner wall of the casing string  64  and the packer  68 . Fluid is continuously pumped downhole during this step in the process thereby increasing the pressure to the point that tension sleeve  70  connecting the setting tool  10  to the packer  68  shears in tension. The pressure required to shear the tension sleeve  70  from the packer  68  is higher than that required to shear the pins  46 . This position, the “shear-off” packer position, is shown in  FIGS. 4–6 . 
   Once the packer  68  has been set, the next step is to open the valve within the packer  68  so that the treatment fluids can be pumped down into the workstring into the formation. This is accomplished by bleeding off the pressure of the fluid being pumped down through the workstring into the setting tool  10 . By bleeding off the pressure, the spring  16 , which in the shear-off packer position is in compression, forces the inner mandrel  14  to move downward, which in turn pushes against a sliding valve  72  formed within the packer  68 . This action forces the sliding valve  72  downward, which in turn aligns ports  76  within the sliding valve  72  with a port  78  formed within packer mandrel  74 , which in turn, communicates with a subterranean formation. 
   The setting tool  10  is locked into this position by activation of the locking device  50 . It is this position that the locking keys  52  recess into the groove  56 . Retaining spring  54  forces the locking keys  52  into engagement with the groove  56 , which axially fixes the inner mandrel  14  to the outer sleeve  12 . The setting tool  10  is held in this position while the treatment fluids are pumped into the subterranean formation. When the treatment of this region of the subterranean formation is complete, the entire workstring is pulled out of the well. As this occurs, the sliding valve  72  moves into the closed position thereby isolating the inside of the well from the subterranean formation. 
   Once the workover is complete, the workstring and setting tool  10  are pulled out of the well, the packer  68  is drilled out of the casing string  64  or wellbore, as is the case, and the well is then prepared for being taken back on line. 
   Therefore, the present invention is well adapted to carry out the objects and attain the ends and advantages mentioned as well as those that are inherent therein. While numerous changes may be made by those skilled in the art, such changes are encompassed within the spirit of this invention as defined by the appended claims.