Abstract:
An apparatus for running a liner into a wellbore may include an inner string, a device coupled to the inner string that is operable to engage the interior of the liner and facilitates running of the liner into the wellbore, and a control mechanism operable to control fluid communication between the interior of the liner and the wellbore. A method of running a liner into a wellbore may include the steps of positioning an inner string into the liner, wherein the inner string includes a device operable to engage the interior of the liner, engaging the interior of the liner, and supplying a fluid pressure to move the liner relative to the inner string to advance the liner into the wellbore.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   This application claims benefit of U.S. Provisional Patent Application Ser. No. 60/973,438, filed on Sep. 18, 2007, which application is herein incorporated by reference in its entirety. 

   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention generally relates to completion operations in a wellbore. More particularly, the invention relates to running casings in extended reach wells. 
   2. Description of the Related Art 
   In extended reach wells or wells with complex trajectory, operators often experience difficulty in running a liner/casing past a certain depth or reach. The depth or reach of the liner is typically limited by the drag forces exerted on the liner. If further downward force is applied, the liner may be pushed into the sidewall of the wellbore and become stuck or threaded connections in the liner may be negatively impacted. As a result, the liners are prematurely set in the wellbore, thereby causing hole downsizing. 
   Various methods have been developed to improve liner running abilities. For example, special low friction centralizers or special fluid additives may be used to reduce effective friction coefficient. In another example, floating a liner against the wellbore may be used to increase buoyancy of the liner, thereby reducing contact forces. 
   There is a need, therefore, for apparatus and methods to improve tubular running operations. 
   SUMMARY OF THE INVENTION 
   In one embodiment, a method of running tubulars, such as liners and casings, include running the tubular to a target depth or to a depth determined by frictional resistance. Then, the tubular may be urged down by generating an active piston force between a seal and a liner shoe. 
   In one embodiment, an apparatus for running a liner into a wellbore may comprise an inner string having a bore therethrough, and a tubular engagement device coupled to the inner string. The device is operable to engage the interior of the liner. The device is also operable to facilitate movement of the liner relative to the inner string using a fluid pressure. 
   In one embodiment, a method of running a liner into a wellbore may comprise the step of positioning an inner string in the liner. The inner string may have a seal member operable to engage the interior of the liner. The method may also include the step of pressurizing an internal area between the seal member and the interior of the liner to provide a pressure force against the interior of the liner. The method may further include the step of displacing the liner relative to the inner string using the pressure force. 
   In one embodiment, a method of running a liner into a wellbore may comprise the step of positioning an inner string into the liner. The inner string may have a piston operable to engage the interior of the liner. The method may also include the step of actuating the piston to engage the interior of the liner. The method may further include the step of displacing the liner relative to the inner string using the piston. 
   In one embodiment, a method of running a liner into a wellbore may comprise the step of positioning an inner string into the liner. The inner string may have a device operable to engage the interior of the liner. The method may also include the step of engaging the interior of the liner using the device. The method may further include the step of supplying a fluid pressure to move the liner relative to the inner string. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     So that the manner in which the above recited features of the present invention can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. 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, for the invention may admit to other equally effective embodiments. 
       FIGS. 1A and 1B  are views of a liner equipped with an inner string having a piston device. The liner is located at a first position in a wellbore. 
       FIGS. 2A and 2B  are views of the liner in a second location in the wellbore, the liner being moved by actuation of the piston device. 
       FIG. 3  shows the liner having an expandable liner hanger expanded against a casing. 
       FIG. 4  shows an inner string equipped with another embodiment of the piston device. As shown, the piston device is in the unactuated position. 
       FIG. 5  shows the piston device of  FIG. 4  in the actuated position. 
       FIG. 6  shows an inner string equipped with yet another embodiment of the piston device. As shown, the piston device is in the unactuated position. 
       FIG. 7  shows the piston device of  FIG. 6  in the actuated position. 
       FIG. 8  shows a telescopic liner assembly. 
       FIG. 9  shows the telescopic liner assembly extended using an embodiment of the piston device. 
       FIG. 10  shows expansion of the telescopic liner assembly after extension. 
   

   DETAILED DESCRIPTION 
   In one embodiment, a liner  100  is assembled conventionally on a rig floor. The liner  100  is suspended from the rig floor and held in place using slips, such as from a spider or a rotary table. A false rotary table may be mounted above the slips holding the liner  100 . Then, an inner string  120  is run into the liner  100 , as shown in  FIGS. 1A and 1B . 
     FIG. 1A  is an external view of the liner  100 , and  FIG. 1B  is an internal view of the liner  100 . The liner  100  may include a casing shoe  130  disposed at an end thereof. A lower portion of the inner string  120  may include a device, such as a seal cup  125 , to allow pressurizing the internal area  115  of the liner  100  between the shoe  130  and the seal cup  125 . In one embodiment, the inner string  120  may include a piston assembly instead of or in addition too the seal cup  125 . The inner string  120  may also include an anchoring or latching device  140  to prevent relative axial movement between liner  100  and the inner string  120 . In one embodiment, the inner string  120  may be a drill pipe. The inner string  120  may also include an expansion tool  160 , such as a rotary expander, a compliant expander, and/or a fixed cone expander, to expand at least a portion of the liner  100 . 
   The inner string  120  may be run all the way to the shoe  130  or to any depth within the liner  100 . After the inner string is located in the liner  100 , the anchoring device  140  may be actuated to secure the inner string  120  to the liner  100 . After the inner string  120  is assembled, the liner  100  is released from the rig floor and is run into the wellbore  150  to a particular depth. The depth to which the liner  100  is run may be limited by torque or drag forces, as illustrated in  FIG. 1A . In one embodiment, a ball  132  or dart is dropped to close a circulation valve at the shoe  130 . In another embodiment, circulation may also be closed using a control mechanism, such as a velocity valve or another closure device known to a person of ordinary skill. When the released ball  132  passes by the anchor device  140 , the ball  132  may de-actuate the anchor device  140  to release the liner  100  from the inner string  120 . After the ball  132  closes circulation, pressure is supplied to increase the pressure in the internal area  115  between the seal cup  125  and the shoe  130 . The pressure increase exerts an active liner pushing force against the shoe  130 , thereby causing the liner  100  to travel down further into the wellbore  150 . In this respect, the active liner pushing force is equal to the pumping pressure multiplied by the piston area within the liner  100 . The internal pressurization of the liner  100  may help alleviate a tendency of the liner  100  to buckle as it travels further into the wellbore  150 . In one embodiment, the active liner pushing force is provided in a direction that is similar or parallel to the direction of the wellbore  150 . In this respect, the effect of the drag forces is reduced to facilitate movement of the liner  100  within the wellbore  150 . 
   After the liner  100  has been extended into the wellbore  150 , the pressure in the internal area  115  may be released. The inner string  120  may then be lowered and/or relocated in the liner  100 , thereby repositioning the seal cup  125 . The tools, such as the seal cups  125 , may be positioned at the top or at any location within the liner  100 . The seal cups  125  may be stroked within the liner  100  numerous times. The pressure may again be supplied to the internal area  115  to facilitate further movement of the liner  100  within the wellbore  150 . This process may be repeated multiple times by releasing the pressure in the liner  100  and re-locating the inner string  120 . 
   In one embodiment, a hydraulic slip  170 , or other similar anchoring device, may be coupled to the liner  100  and/or the inner string  120  to resist any reactive force provided on the string or the liner that will push the string or liner in an upward direction or in any direction toward the well surface. The hydraulic slip  170  may be operable to prevent the inner string  120  from being pumped back to the surface, while forcing the liner  100  into the wellbore  150 . In one embodiment, the hydraulic slip  170  may be coupled to the interior of the liner  100  to engage the inner string  120 . In one embodiment, the hydraulic slip  170  may be coupled to the inner string  120  to engage the liner  100 . In one embodiment, the hydraulic slip  170  may be coupled to the exterior of the liner  100  to engage the wellbore  150 . 
   In another embodiment, the liner  100  may optionally include an expandable liner hanger  108 , as shown in  FIGS. 2A and 2B . As shown, the liner hanger  108  is equipped will a sealing member  109 , such as an elastomer.  FIG. 2A  is an external view of the liner  100 , and  FIG. 2B  is an internal view of the liner  100 . When the inner string  120  is pulled all the way to the liner hanger  108 , the expansion tool  160  may be activated. The expansion tool  160  may be activated from a (collapsed) travel position to a (enlarged) working position. The liner hanger  108  may be expanded using any tool and technique known in the art. Expansion of the liner hanger  108  anchors the liner  100  and seals the liner top. Alternatively, a conventional liner hanger may be used. 
     FIG. 3  shows the liner hanger  108  expanded and set against casing  101 . The inner string  120  may then be pulled out of the wellbore  150 . In one embodiment, the liner  100  may be cemented in the wellbore  150 . In one embodiment, the liner  100  may be radially expanded. In one embodiment, the liner  100  may be expanded at one or more discrete locations to effect zonal isolation or sand production control. In one embodiment, the liner  100  may include a sand control screen, such as an expandable screen. 
     FIG. 4  shows one embodiment of the inner string  120  (also referred to as a “running tool”) equipped with a jack piston device  200 . The inner string  120  is shown disposed in a liner  100 . The liner  100  is provided with a shoe  130 . The inner string  120  includes a seal  225  for sealing against the liner  100 . In one embodiment, the piston device  200  includes a housing  250  movably disposed on the exterior of the inner string  120 . A port  255  is provided to allow fluid communication between the interior of the inner string  120  and the housing  250 . Seals may be disposed between the piston device  200  and the inner string  120 . A slip  260  is supported in the housing  250  and is radially movable in response to a pressure in the housing  250 . 
   In operation, the liner  100  and the inner string  120  may be lowered into the casing  101  to a depth at which further progress is impeded. A ball  132  is released into the liner  100  to seat in a valve in the shoe  130  to close fluid circulation. Pressure increase in the inner string  120  causes the slips  260  to move radially outward into engagement with the liner  100 . Further pressure increase causes the piston device  200  to move relative to the inner string  120  and in the direction of the shoe  130 . This movement is due to the fluid pressure acting on piston surface  258  provided in the housing  250 . Because the piston device  200  is engaged to the liner  100  via the slips  260 , the liner  100  is moved along with the piston device  200 , thereby advancing the liner  100  further into the wellbore  150 . In  FIG. 5 , it can be seen that the piston device  200  has moved closer to the seal  225  and that the liner  100  has traveled down. After the liner  100  has moved, the pressure in the inner string  120  may be reduced to retract the slips  260 . Thereafter, the piston device  200  may be re-pressurized so that the process may be repeated to advance the liner  100  further into the wellbore  150 . In one embodiment, the inner string  120  may be repositioned so that the process may be repeated to advance the liner  100  further into the wellbore  150 . In one embodiment, the pressure contained by the seal  225  also acts on the liner shoe  130  so that the combination of this pressure plus the force exerted by the piston device  200  pushes the liner  100  further into the wellbore  150 . 
   In one embodiment, a biasing member  270  may be provided to facilitate repositioning of the piston device  200  relative to the port  255 . In one embodiment, the biasing member  270  may be a spring that is disposed between the seal  225  and the piston device  200 , such that it engages a shoulder on the inner string  120  at one end and engages the housing  250  at the opposite end. As the piston device  200  is moved toward the seal  225 , the spring is compressed, as shown in  FIG. 5 . After the pressure in the inner string  120  is reduced and the slips  260  are disengaged from the liner  100 , the spring will exert a biasing force to move the piston device  200  to its original position relative to the port  255 . 
   In one embodiment, a plurality of piston devices may be used on an inner string  120 .  FIG. 6  shows an inner string  120  with two piston devices  301  and  302 . In one embodiment, a first biasing member  311  is disposed between a shoulder  305  on the inner string  120  and the first piston device  301 , and a second biasing member  312  is disposed between the two piston devices  301  and  302 . A landing seat  320  is provided in the inner string  120  to close circulation between the inner string  120  and the liner  100 , and/or the inner string  120  and the wellbore  150 . In one embodiment, the inner string  120  may be equipped with the seal configuration as shown in  FIG. 1B  or  4 . 
   In operation, a ball  132  is released into the inner string  120  to seat in the landing seat  320  to close fluid circulation. Pressure increase in the inner string  120  causes the slips  360  to move radially outward into gripping engagement with the liner  100 . Further pressure increase causes the piston devices  301  and  302  to move relative to the inner string  120  and in the direction of the shoe  130 . This movement is due to the piston surfaces  358  provided in the housings  350  of the piston devices  301  and  302 . Because the piston devices  301  and  302  are engaged to the liner  100  via the slips  360 , the liner  100  is moved along with the piston devices  301  and  302 , thereby advancing the liner  100  further into the wellbore  150 . 
   In  FIG. 7 , it can be seen that the piston devices  301  and  302  have moved closer to the shoulder  305  and that the liner  100  has traveled down. After the liner  100  has moved, the pressure in the inner string  120  may be reduced to retract the slips  360 . After the pressure is reduced, the biasing members  311  and  312  are operable to move the piston devices  301  and  302  back to their original position. Thereafter, the piston devices  301  and  302  may be re-pressurized so that the process may be repeated to advance the liner  100  further into the wellbore  150 . In one embodiment, the inner string  120  may be repositioned so that the process may be repeated to advance the liner  100  further into the wellbore  150 . 
   In one embodiment, the inner string  120  may be used to extend a telescope liner assembly  400 , as shown in  FIG. 8 .  FIG. 8  shows the liner assembly  400  having an inner liner  401  at least partially disposed within an outer liner  402 . One or more seals  405  may be disposed between the inner liner  401  and the outer liner  402 . In one embodiment, the inner string  120  disposed in the liner assembly  400  is equipped with a seal piston configuration as shown in  FIGS. 1B  and/or  4 . 
   A seal piston  420  may be positioned in the liner assembly  400  such that the seal  125  is adapted to engage the outer liner  402 , as shown in  FIG. 9 . The seal piston  420  may further include an anchoring device  140  and/or an expansion tool  160 . In one embodiment, a seal piston  410  may be positioned in the inner liner  401  such that the seal  125  engages the inner liner  401 . The seal piston  410  may further include an anchoring device  140  and/or an expansion tool  160 . In one embodiment, the inner string  120  may include two seal pistons  410  and  420  with one located in each liner  401  and  402 . In one embodiment, the inner string  120  may equipped with jack piston devices instead of the seal piston and/or both. 
   In operation, the inner string  120 , having either seal piston  420  or  410 , or both, may be introduced into the liner assembly  400  and secured in the liner assembly  400  via anchoring devices  125 . The inner string  120  and the liner assembly  400  may be lowered into the wellbore  150  to a predetermined depth. As described above, a ball, a dart, or other triggering mechanism may be used to deactivate one or both of the anchoring devices  125  from engagement with the liner assembly  400 . Pressure may then be supplied through the inner string  120 , thereby pressurizing the liner assembly  400  against the seal pistons  420  and/or  410 , and providing an active liner force to telescope the inner liner  401  into the wellbore  150  relative to the outer liner  402 . Further pressurization may then allow the inner liner  401  and the outer liner  402  to advance further into the wellbore  150  relative to the inner string  120 . The pressure may be released to allow relocation and/or removal of the inner string  120 . This process may be repeated to even further advance the liner assembly  400  into the wellbore  150 . 
   In one embodiment, the liner assembly  400  may be equipped with a locking mechanism such that after the inner liner  401  is extended, the piston devices  410  and/or  420  may be used to move the inner liner  401  and the outer liner  402 . 
   In one embodiment, the inner liner  401  and the outer liner  402  may initially be releasably connected. During operation, the inner and outer liners  401  and  402  are moved along in the wellbore  150 . At a predetermined depth, the releasable connection may be sheared or otherwise disconnected, thereby allowing the inner liner  401  to be extended relative to the outer liner  402 . 
   In one embodiment, after the inner liner  401  has been extended from the outer liner  402 , the inner liner  401  may be optionally radially expanded, as shown in  FIG. 10 . In one embodiment, the outer liner  402  may also be radially expanded. 
   In further embodiments, the liner (any of  100 ,  400 ,  401 ,  402 ) may be equipped with a drilling or reaming device at or on the shoe, such that the borehole may be drilled or reamed during the running operation. 
   While the foregoing is directed to embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.