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PRIORITY INFORMATION 
   This application claims the benefit of U.S. Provisional Application No. 60/362,306 on Mar. 7, 2002. 

   FIELD OF THE INVENTION 
   The field of this invention is expansion of tubulars and screens downhole in a single trip into the wellbore. 
   BACKGROUND OF THE INVENTION 
   The field of expansion of tubulars has gained in popularity. In early attempts, a tubular segment was collapsed to get it into a piece of casing and then, when in position; the tubular was expanded to its original dimension. This technique was used for casing patches where the tubular to be expanded was of a fairly short length. One example of this technique is U.S. Pat. No. 5,785,120. Other techniques involved hydraulic pressure applied to a swage to force it through a tubular for expansion. One example of this technique is U.S. Pat. No. 6,029,748. A shortcoming of pressure techniques are that they depend on a solid tubular to avoid losing the driving pressure. For this reason, pressure techniques are not suited for slotted liner or screen expansions. Another pressure technique is illustrated in U.S. Pat. Nos. 6,235,148; 5,348,095 and 6,070,671. 
   Various expandable well screen products have been developed as illustrated in U.S. Pat. Nos. 6,263,966; 5,901,789 and 6,315,040. Bottom up expansion of a slotted liner using a conical swage is illustrated in U.S. Pat. Nos. 5,667,011 and 5,366,012. Roller devices have been used to provide thrust to a swage as shown in U.S. Pat. No. 5,960,895. Weatherford has advertised roller devices for expansion of tubulars to conform to the shape of the borehole. A problem with such a device, particularly when expanding screen is that some portions of the screen get expanded more than others with structural failures being the result. 
   What is needed and yet not made available by the prior devices or techniques is a way to expand solid tubing, slotted tubing or screen in a single trip while at the same time taking into consideration the need to not overstress the expanded tubular or screen. Equipment that allows the assembly to be run in the hole together and then selectively allows disengagement after support is established downhole, is also a feature of the present invention. An anchor that can be set and released repeatedly and fit into the expanded tubular or screen is also another aspect of the present invention. Yet another aspect is an anchor that is configured to obtain a sufficient grip for driving the swage but is otherwise limited in its axial travel so as to avoid needless stressing of the tubular of screen after it has already been expanded by about 25% or more. These and other features of the invention will be more readily apparent to a person skilled in the art from a review of the description of the preferred embodiment, which appears below. 
   SUMMARY OF THE INVENTION 
   A one trip system for expanding a tubular that is solid or perforated or a screen is disclosed. The downhole assembly features a hydraulic anchor that can be set, released and repositioned to repeat the process, is used. The anchor is small enough to go through the tubular or screen after initial expansion. The anchor&#39;s maximum extension is designed to avoid overstressing the already expanded tubular or screen. An expansion tool is hydraulically driven with the initial portion of the stroke delivering an enhanced force. The expansion tool initially supports the tubular or liner but subsequently releases during the first stroke, after the tubular or screen is fully supported. 

   
     DETAILED DESCRIPTION OF THE DRAWINGS 
       FIGS. 1   a – 1   c  are a sectional elevation of the assembly showing the anchor, the expansion tool, and the running tool in the run in position; 
       FIG. 2  is a section of the anchor in the run in position; 
       FIG. 3  is a section of the anchor in the set position; 
       FIG. 4  is a section of the anchor in the emergency release position; 
       FIG. 5  is a detailed view adjacent the lower end of the slips on the anchor; 
       FIGS. 6   a – 6   b  are a section view of a portion of the running tool in the run in position; 
       FIGS. 7   a – 7   b  show the same portion of the running tool after the beginning of the stroke; 
       FIGS. 8   a – 8   b  show the position of the running tool after release from the tubular or screen; 
       FIGS. 9   a – 9   b  show the running tool fully stroked. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Referring to  FIGS. 1   a  and  2 , the anchor  10  has a top sub  12 , which is connected at thread  14  to body  16 . A rupture disc  20  closes off a passage  18 . At its lower end, the body  16  is connected to bottom sub  22  at thread  24 . Body  16  supports a seat  26  with at least one snap ring  28 . A seal  30  seals between body  16  and seat  26 . The purpose of seat  26  is to receive a ball (not shown) to allow pressure buildup in passage  32  to break rupture disc  20 , if necessary. A passage  34  communicates with cavity  36  to allow pressure in passage  32  to reach the piston  38 . Seals  41  and  43  retain the pressure in cavity  36  and allow piston  38  to be driven downwardly. Piston  38  bears down on a plurality of gripping slips  40 , each of which has a plurality of carbide inserts or equivalent gripping surfaces  42  to bite into the casing or tubular. The slips  40  are held at the top and bottom to body  16  using band springs  44  in grooves  46 . The backs of the slips  40  include a series of ramps  48  that ride on ramps  50  on body  16 . Downward, and by definition outward movement of the slips  40  is limited by travel stop  52  located at the end of bottom sub  22 .  FIG. 3  shows the travel stop  52  engaged by slips  40 . The thickness of a spacer  54  can be used to adjust the downward and outward travel limit of the slips  40 . 
   Located below the slips  40  is closure piston  56  (see  FIGS. 2–5 ) having seals  58  and  60  and biased by spring  62 . A passage  64  allows fluid to escape as spring  62  is compressed when the slips  40  are driven down by pressure in passage  34 . Closure piston  56  is located in chamber  57  with ratchet piston  59 . A ratchet plug  61  is biased by a spring  63  and has a passage  65  though it. A dog  67  holds a seal  69  in position against surface  71  of ratchet piston  59 . A Seal  73  seals between piston  59  and bottom sub  22 . Area  75  on piston  59  is greater than area  77  on the opposite end of piston  59 . In normal operation, the ratchet piston  59  does not move. It is only when the slips  40  refuse to release and rupture disc  20  is broken, then pressure drives up both pistons  56  and  59  to force the slips  40  to release and the ratchet teeth  79  and  81  engage to prevent downward movement of piston  56 . Passage  65  allows fluid to be displaced more rapidly out of chamber  83  as piston  59  is being forced up. 
   Referring now to  FIG. 1   b , the pressure-magnifying or expansion tool  66  has a top sub  68  connected to bottom sub  22  of anchor  10  at thread  70 . A body  72  is connected at thread  74  to top sub  68 . A passage  76  in top sub  68  communicated with passage  32  in anchor  10  to pass pressure to upper piston  78 . A seal  80  is retained around piston  78  by a snap ring  82 . Piston  78  has a passage  84  extending through it to provide fluid communication with lower piston  86  through tube  88  secured to piston  78  at thread  90 . Shoulder  92  is a travel stop for piston  78  while passage  94  allows fluid to move in or out of cavity  96  as the piston  78  moves. Tube  88  has an outlet  98  above its lower end  100 , which slidably extends into lower piston  86 . Piston  86  has a seal  102  held in position by a snap ring  104 . Tube  106  is connected at thread  108  to piston  86 . A lower sub  110  is connected at thread  112  to tube  106  to effectively close off passage  114 . Passage  114  is in fluid communication with passage  76 . Passage  116  allows fluid to enter or exit annular space  118  on movements of piston  86 . Shoulder  120  on lower sub  110  acts as a travel stop for piston  86 . At full stoke, castellations  121  engage castellations  123  to allow torque transmission. A ball  122  is biased by a spring  124  against a seat  126  to seal off passage  128 , which extends from passage  114 . As piston  86  reaches its travel limit, ball  122  is displaced from seat  126  to allow pressure driving the piston  86  to escape just as it comes near contact with its travel stop  120 . Thread  130  allows mandrel  132  of running tool  134  to be connected to pressure magnifying tool  66 . 
   Running tool  134  has a body  136  (see Figs  1   c  and  6 – 9 ) having a lower end  138  and adjacent openings  140  through which extend dogs  142 , each of which have an exterior thread pattern  144  to mate with thread pattern  146  of the tubular, solid or slotted or a screen, all collectively referred to and defined for the purposes of this application as “tubular”  176 . A plurality of leaf springs  148  bias all the dogs radially inwardly when support for the dogs  142  is removed, as shown in  FIG. 9.A  support sleeve  150  is disposed between body  136  and mandrel  132  and is initially secured with shear pin  152 . Openings  154  in sleeve  150  each have a locking dog  156  extending though them and into grooves  158 . Mandrel  132  supports locking dogs  156  in their respective grooves  158  for run in, as shown in  FIG. 6 . A groove  160  holds a snap ring  162  whose purpose will be explained below. Support sleeve housing  166  is retained by shear pin  164  to body  136 . End cap  168  is connected at thread  170  to support sleeve housing  166 . Passage  172  is a vent for annular space  173 . Shoulder  174  on housing  166  eventually retains support sleeve  150  via snap ring  162 , as shown in  FIG. 9   b . Threads  178  secure the swage  180 , which in the preferred embodiment is of a fixed maximum dimension. It is worth noting that the tubular  176 , to be expanded, extends uphole past the anchor  10 . This is done so that in the initial anchoring, the slips  40  can obtain a sufficient grip to allow the swage  180  to advance despite the fact that the outward extension of the slips  40  is limited. The limitation of outward movement of the slips  40  insures that on subsequent cycles, when the anchor  10  has advanced into a portion of the tubular  176  that has previously been expanded, the tubular  176  is not further stressed after already having been expanded. Tubular  176  further comprises an exterior surface treatment that is schematically shown as  177  for the purpose of enhancing the grip against the schematically illustrated lowermost wellbore casing  179  from which support will ultimately be provided for the tubular  176 . 
   The operation of the tool in the performance of the service will now be explained. The assembly of the anchor  10 , the force magnifying tool  66 , the running tool  134 , which supports the tubular  176  at teeth  144 , and the swage  180  are placed in position in the casing  179 . Pressure applied to passage  32  reaches piston  38 , pushing it and slips  40  down with respect to body  16 . Ramps  48  ride down ramps  50  pushing the slips  40  outwardly against the return force of band springs  44 . Inserts  42  bite into the casing or tubing and eventually slips  40  hit their travel stop  52 . Piston  56  is moved down against the bias of spring  62 . The pressure continues to build up after the slips  40  are set, as shown in  FIG.3 . The pressure applied in passage  76  of pressure magnification tool  66  forces pistons  78  and  86  to initially move in tandem. This provides a higher initial force to the swage  180 , which tapers off after the piston  78  hits travel stop  92 . Once the expansion with swage  180  is under way, less force is necessary to maintain its forward movement. The tandem movement of pistons  78  and  86  occurs because pressure passes through passage  84  to passage  98  to act on piston  86 . Movement of piston  78  moves tube  88  against piston  86 . After piston  78  hits travel stop  92 , piston  86  completes its stroke. Near the end of the stroke, ball  122  is displaced from seat  126  removing the available driving force of fluid pressure as piston  86  hits travel stop  120 . This is a signal to surface personnel that the stroke is complete and that pressure can be turned off. It is worth noting that during removal of the assembly, piston  86  will assume the fully stroked position and ball  122  will be off of seat  126  so that the string to the surface will drain and will not be pulled wet. 
   With the pressure removed from the surface, spring  62  returns the slips  40  to their original position by pushing up piston  56 . If it fails to do that, a ball (not shown) is dropped on seat  26  and pressure to a high level is applied to rupture the rupture disc  20  so that piston  56  can be forced up with pressure. When piston  56  is forced up so is piston  59  due to the difference in surface areas between surfaces  75  and  77 . Ratchet plug  61  is pushed up against spring  63  as fluid is displaced outwardly through passage  65 . Ratchet teeth  79  and  81  lock to prevent downward movement of piston  56 . 
   If more tubular  176  needs to be expanded, weight is set down to return the force-magnifying tool  66  to the run in position shown in  FIG. 2  and the entire cycle is repeated until the entire section is expanded to the desired diameter with the swage  180 . 
   The initial stroke of the force-magnifying tool  66  features a release of the tubular  176  by the running tool  134 , as illustrated in  FIGS. 6–9 . Initially, during transportation at the surface and prior to running into the well, the mandrel  132  is retained in a retracted position by lock bolts  182  shown in  FIG. 1   c . These bolts  182  are removed before the assembly is run into the well. The running tool  134  supports the tubular  176  for run in by virtue of the engagement of teeth or thread patterns  144  and  146 . As previously stated, the tubular  176  extends beyond the slips  40  of the anchor  10  such that the radial travel distance of slips  40  when initially pushing tubular  176  and its exterior surface treatment  177  against the casing  179  results in a firm support for the tubular  176  against the casing  178 . As a part of this process, the running tool  134  will have to release its grip on the tubular  176  so that it can be advanced into the tubular to complete the expansion.  FIGS. 6–9  illustrate how that happens as the force-magnifying tool  66  begins its initial stroke. During run in, the support sleeve  150  is secured to body  136  by shear pin  152 . In that position, the dogs  142  are pushed out against the inward bias of leaf springs  148 . There is gripping contact of the tubular  176  by engagement of teeth or thread patterns  144  and  146 . Dogs  156  are supported by mandrel  132  in grooves  158 . Housing  166  is retained by shear pins  164  to body  136 . 
     FIG. 7  shows what happens during initial movement of mandrel  132 . Shear pin  152  breaks. Groove  184  on mandrel  132  comes under dogs  156 . Lower sub  110  engages support sleeve  150  driving it down against end cap  168 , as shown in  FIG. 8 . Fluid in annular space  173  is driven out through passage  172 . The force on end cap  168  breaks shear pins  164 . Snap ring  162  is retained by shoulder  174 . The assembly of housing  166  end cap  168  and support sleeve  150  now slide down swage  180 . Meantime, dogs  142  are biased inwardly by leaf springs  148  against mandrel  132 . This retracts teeth or thread pattern  144  back inside body  136 . The tubular is now fully supported from the casing  178  by the expansion of the surface treatment  177  of tubular  176  into the casing  179  and the full release from running tool  134  as described above. 
   It should be noted that there is a taper  186  on the tubular  176  just below the surface treatment  177 . Taper  186  makes it easier to advance the tubular  176  into position where the surface treatment  177 , which is on a larger diameter, will be in position to engage the casing  179  for support of tubular  176 . 
   It should again be emphasized that “tubular” as used herein incorporates solid tubes, perforated or slotted tubes, and screens of any construction. The equipment and method described above allow expansion of any desired length even in deviated wellbores where string manipulation is not practical. The anchor  10  and the force-magnifying tool  66  are built to have an outside diameter that will allow them to easily pass into the expanded tubular  176 . This eliminates the need for long lengths of tubing to connect a swage  180  to the force-magnifying tool  66 , as would be necessary if the anchor  10  and the force-magnifying tool  66  could not pass into the expanded tubular  176 . While the use of a fixed diameter swage  180  is described, a swage that can be positioned between or among several dimensions can also be used. The uniformity of expansion obtained by using a swage at a predetermined diameter avoids the potential failure problem due to uneven expansions that can occur using hydraulically actuated rollers that move responsively to the borehole shape. Swages that fix the expansion and insure that the expansion force is uniformly applied are contemplated even if such swages include rollers that are fixed. Yet another beneficial feature is the anchor  10  design. It has limited radial travel so that when energized in already expanded tubular  176  it will not further stress it to failure in trying to get an anchoring grip. The limited outward movement of the slips  40  provides this protection. To compensate for the limited radial movement when the anchor is still in the casing  179 , the tubular  176  is run up to past the slips  40  on the anchor  10  so that the limited travel of the slips  40  will be sufficient to get a grip on the casing  179  due to the presence of a portion of the tubular  176  around the slips for at least the initial actuation of the anchor  10  and the stroking of swage  180  for transfer of support of the tubular  176  from the running tool  134  to the casing  179 . 
   The foregoing disclosure and description of the invention are illustrative and explanatory thereof, and various changes in the size, shape and materials, as well as in the details of the illustrated construction, may be made without departing from the spirit of the invention.

Summary:
A one trip system for expanding a tubular that is solid or perforated or a screen comprises a downhole assembly that features a hydraulic anchor that can be set, released and repositioned to repeat the process. The anchor is small enough to go through the tubular or screen after initial expansion. The anchor&#39;s maximum extension is designed to avoid overstressing the already expanded tubular or screen. An expansion tool is hydraulically driven with the initial portion of the stroke delivering an enhanced force. The expansion tool initially supports the tubular or liner but subsequently releases during the first stroke, after the tubular or screen is fully supported.