You are an expert at summarizing long articles. Proceed to summarize the following text:

You are an expert at summarizing long articles. Proceed to summarize the following text: 
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to expanding tubulars in a well and more particularly, to methods and tools utilizing technology directed towards downhole expansion of tubulars. 
     2. Background of the Related Art 
     There are many types of operations that must be performed at some depth in a well and various tools and methods have been developed to perform these downhole operations. Downhole tools for example, are available with means for setting after being placed at some depth in a well. The tools are actuated in order to fix or set them in place in the well. In some cases, setting involves the setting of a slip to secure the position of the tool against the casing walls. For example, with casing liner, one string of casing is hung in the well at the end of a previous string and the liner must be set at the appropriate depth by actuating slips against the inner wall of the existing casing. In another example, a packer used to isolate an annular area between two tubular members, is set at a particular depth in a well prior to expanding its surfaces against the inner tube and the outer tube walls. 
     There are numerous known ways to set downhole tools. Typically, pressure build up inside or outside the tool is required. In some prior art tools, that pressure is typically communicated through a wall of the tool into a sealed chamber. An actuating piston forms part of the sealed chamber such that the cavity will grow or shrink in volume as the piston moves responsive to the increase or decrease of hydraulic pressure within the tool. These variable-volume cavities outside the wall of the tool are sealed off with eleastomeric O-rings or similar seals. The seals are subject to wear from contamination in wellbore fluids, stroking back and forth in normal operation, and/or temperature or chemical effects from the wellbore fluids. The biggest concern about seal wear is that an open channel could be created through the lateral port in the wall of the tool from inside to outside of the tool, thus upsetting well operations and costing critically expensive downtime for the well operator. 
     A more recent advance, described in U.S. Pat. No. 5,560,426 employs the principles of pressure differential but without fluid communication throughout he wall of the tool. Instead, the applied pressure differential creates a stress which allows the wall of the tool to flex and fracture a locking ring on the outside surface of the tool. When the ring fractures, a piston moves in reaction to the pressure differential and a spring loaded slip is driven onto a cone, thereby setting the tool in the well. While this technology is an improvement over those requiring an aperture in the tool wall, the structure and mechanical operations required are complicated and subject to failure. For example, in the apparatus described in U.S. Pat. No. 5,560,426, an atmospheric chamber is formed on the inside of the tool body as well as the outside. To begin the tool setting sequence, the outer chamber must be opened to the pressure of the well. Opening the outer chamber is performed by dropping a ball into a seat formed at the top of the chamber and then increasing pressure inside of the tubing and body until the ball, seat and chamber are blown down into the well bore. Assuming that the interior chamber is successfully opened to well pressure, the design also requires a flexing of the tool wall in order to fracture a frangible locking ring. The required flexing that must take place in the wall is difficult to calculate and predict when designing the tool and the locking ring. 
     Other problems associated with current downhole tools are related to space. A liner hanger with its slips and cones necessarily requires a certain amount of space as it is run-into the well. This space requirement makes it difficult to insert a liner hanger through previously installed tools like mechanical packers because the inside diameter of the previously installed tool is reduced. Space problems also arise after a slip and cone tool is set in a well because adequate clearance must be available for the subsequent flow of liquids like cement through the annular area between the tubulars. 
     Technology is emerging for selectively expanding the diameter of tubing or casing in a well. FIG. 1 depicts an expansion apparatus  100  which can be lowered into a well to a predetermined location and can subsequently be used to expand the diameter of the tubular member. The apparatus  100  comprises a body having two spaced-apart, double conical portions  102   a, b  with rollers  105  mounted therebetween. The rollers  105  may be urged outwards by application of fluid pressure to the body interior via the running string  103 . Fluid pressure in the running string urges the conical portions  102   a, b  towards each other and forces the rollers  105  into contact with a wall  107  of a tubular member  110  sufficient to deform the wall of the tubing. Each roller  105  defines a circumferential rib  115  which provides a high pressure contact area. Following the creation of an expanded area  120  visible in FIG. 2, the fluid pressure in communication with the apparatus is let off, allowing the rollers  105  to retract. The apparatus  100  is then moved axially a predetermined distance to be re-energized and form another expanded area or is removed from the well. In the embodiment shown in FIGS. 1 and 2, the portions contacting the tube wall are rollers. However, the portions contacting the tubular wall could be non-rotating or could rotate in a longitudinal direction allowing the creation of a continued area of expansion within a tubular body. 
     There is a need therefore, for a slip and cone tool which requires less space as it is inserted into the well. 
     There is a further need for a slip and cone tool that requires less space after it has been set in the well. 
     There is a further need for downhole tools that utilize a removable expansion apparatus for activation. 
     There is a further need for a method of expanding a tubular wall in a well when the portion of the tubular to be expanded is located below a previously set, non collapsible tool. 
     There is a farther need for a downhole tool that can be operated or set in a wellbore by simple, remote means. 
     There is a further need for a downhole tool that can be operated or actuated without the use of chambers. 
     There is a further need for a downhole tool that can be operated without the use of gravity feed balls or other objects dropped from the earth&#39;s surface. 
     SUMMARY OF THE INVENTION 
     The invention relates to methods, apparatus and tools to be used with tubular expansion apparatus. In one aspect of the invention, tools are actuated or operated within a well by selectively expanding the tool wall. More specifically, a tool, like a casing liner hanger is provided with a chamber formed on the exterior surface of the tool creating a pressure differential within the tool. A locking ring around the outside of the tool body normally locks the piston in place. To actuate the tool, the tool wall is urged outward past its elastic limits. The expanding wall physically unlocks a locking ring which then unlocks the piston. Thereafter, hydraulic pressure differences are employed to move the piston to operate the downhole tool. In another aspect of the invention, a tool includes a cone formed thereupon and a multi-part slip disposed around the tool body. To operate the tool, the body is expanded at a first end of the slip and then expanded in an axial direction towards the cone. In this manner, the slip is forced onto the cone by the expanding body and the tool thereby set against the casing wall. In another aspect of the invention, a body is formed with a cone having teeth thereupon. To set the tool, the body of the tool is expanded directly under the toothed cone so as to force the teeth of the cone into contact with the casing wall to set the tool. In yet another aspect of the invention, a first piece of casing is joined to a second, larger diameter casing. By expanding the diameter of the first piece of casing into contact with the second piece of casing, the two are joined together. The joint is formed with helical formations in a manner that provides flow paths around the intersection of the two members for the passage of cement or other fluid. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     So that the manner in which the above recited features, advantages and objects of the present invention are attained and can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to the embodiments thereof 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. 
     FIG. 1 is a is a section view showing an expansion apparatus in an actuated state; 
     FIG. 2 is a is a section view showing an expansion apparatus; 
     FIG. 3 is a section view showing an unactuated tool of the present invention; 
     FIG. 3 a  is a section view showing the tool of FIG. 3 in an actuated state; 
     FIG. 4 is a section view showing another embodiment of the present invention; 
     FIG. 5 is a section view showing another embodiment of the present invention; 
     FIG. 5 a  is a section view showing the tool of FIG. 5 in an actuated position; 
     FIG. 6 is a section view showing another embodiment of the present invention; 
     FIG. 7 is a section view showing another embodiment of the present invention; 
     FIG. 8 is a section view showing yet another embodiment of the present invention; 
     FIG. 9 is a section view showing an expansion apparatus; 
     FIG. 10 is a view showing tubing with a helical formation formed therein; and 
     FIG. 11 is a section view showing various lengths of tubing having been expanded. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     A first embodiment of the invention is shown if FIG.  3 . For illustrative purposes, the tool is shown in use with a casing lining hanger. However, those skilled in the art will appreciate that the tool described and claimed herein can be used to perform any number of tasks in a well wherein simple, reliable and remote actuation or operation is required. The casing line hanger in FIG. 3 includes a mechanism for setting a number of slips  200  by pushing them along a cone  205 . In the run-in position shown in FIG. 3, the slips  200  are retracted to facilitate the insertion of the downhole tool in the wellbore. Ultimately, as can be seen by comparing FIGS. 3, and  3 A the slips  200  will be driven up the sloping surface of cone  205 . The slips  200  are held by a retainer  210 , which in turn abuts a piston assembly  215 . Piston assembly  215  includes a piston  260 , a lug  230 , which in the run-in position is trapped in groove  270  by sleeve  240 . Sleeve  240  abuts lug  230  on one end, while the other end of lug  230  is in groove  270 , thus effectively trapping the piston assembly  215  from longitudinal movement. A support ring  250  is secured to the wall  255  of the tool. The support ring  250  supports a spring  255 , which, when the lug  230  is liberated by movement of sleeve  240 , results in biasing the piston  260  in a manner which will drive the slips  200  up the cone  205 , as shown in FIG.  3 A. 
     Piston assembly  215  has an extending segment  265  which extends into an atmospheric chamber  275 . The pressure in chamber  275  is preferably atmospheric, but can be a different pressure up to near the annulus pressure. Because the hydrostatic pressure acting on piston assembly  215  in the wellbore exceeds the opposing pressure exerted on extending segment  265  within cavity  275 , piston assembly  215  tends to want to move downward against lock ring  280 . 
     In the preferred embodiment, the locking ring is broken when the wall of the tool is expanded by a radial force transmitted from inside the wall. This expansion of the tool wall by an apparatus like the mechanism shown in FIGS. 1 and 2 puts an increasing stress on lock ring  280 , causing the lock ring, which can be preferably of a ceramic material, to break. Since the piston assembly  215  is in a pressure imbalance and the pressure internally in chamber  275  is significantly lower than the hydrostatic pressure in the annulus outside the tool, the piston assembly  215  shifts further into the chamber  275 , as illustrated in FIG.  3 A. Once sufficient movement into chamber  275  has resulted in a liberation of lug  230 , spring  255  moves the piston assembly  215  upwardly, thus camming the slips  200  up the cone  205 . 
     In a second embodiment of the invention, the atmospheric chamber in the tool is formed in such a way as to make the spring loaded function of the tool unnecessary. FIG. 4 depicts the second embodiment in its unset or run-in position. A piston  405  is held in a locked position within a chamber  407  by a locking ring  410  that is seated in a groove  415 . Unlike the previous embodiment, the piston is arranged in such a way that when actuation of the tool is initiated by breaking the locking ring  410  and allowing the piston  405  to travel in response to the pressure differential, an arm  420  formed at the end of the piston  405  directly contacts the slip  425  and forces the slip upon the cone  430 , thereby setting the tool. The embodiment herein described avoids the use of a spring loaded mechanism, saving parts and expense and complexity. As in the embodiment of FIGS. 3 and 3A, the locking ring is fractured by a radial force applied to the interior wall  440  of the tool by an expansion apparatus  460 . 
     Another embodiment of the invention is shown in FIGS. 5 and 5A. In this embodiment, the tool consists of a body  505 , a multi-piece slip  510  disposed around the body and attached to a ring  516  and a cone  515  mounted on the outer surface of the body. The slip assembly  510  includes toothed members constructed and arranged to contact the wall of the casing when the tool is set. In this embodiment, the tool also includes a slight undulation or profile  512  in the tool body under a cut-out portion  511  of ring  516 . The profile  512 , in the preferred embodiment, is formed in the tool wall at the surface of the well and houses a roller of the expansion apparatus  550  in a partially energized state. By pre-forming the profile  512 , the apparatus  550  is located at the correct location with respect to the tool body and the profile  512  additionally retains the tool in the unset or run-in position. 
     In order to operate the tool of this embodiment, the expansion apparatus  550  is energized at the location of the profile. Thereafter, the expansion apparatus is urged upwards while energized. The apparatus may also be rotated while it is being urged upwards. As the tool is pulled, the profile  512  assumes the shape shown in FIG. 5A as it is axially extended in the direction of the cone  515 . In this manner the slips  510  are urged onto the cone thereby pressing the toothed portion of the slip against the casing wall to set the hanger. When the slip has moved far enough onto the cone for the hanger to be securely set, the expansion tool is de-energized and removed from the well bore. 
     In another embodiment depicted in FIG. 6, a liner hanger  600  includes a body  602  and a cone  605  formed thereupon. Disposed around the body is a ring  650  having a groove  610  formed in its inner surface  612  which aligns with a groove  615  formed on the outer surface  617  of the body  602 . A locking ring  608  held in the grooves  610 ,  615  prevents the ring  650  from moving in relation to the body. The ring  650  is further suspended within the wall of casing  620  by means of at least two leaf springs  622  mounted on the outer surface of the ring  650 . In this embodiment, when the lock ring  608  is broken due to expansion of the tool body by an expansion apparatus  650 , the frictional relationship between the ring  650  and the casing wall  620  causes the ring  650  to remain stationary in the wellbore The liner is thereafter set when the tubing string and tool body  602  is pulled upwards and the slip is driven onto the cone. 
     In yet another embodiment of the invention illustrated in FIG. 7, a slip actuated gripping device like a liner hanger  700  for example, is provided having a body  702  without a cone initially formed thereon. In this embodiment, a cone for setting the slip is formed in the wellbore using an expansion apparatus with the capability of expanding a tubular to various, gradually increasing diameters. In the preferred embodiment, slip assembly  710  consisting of a ring and slips is disposed around body  702  and retained during run-in by two rings  708   a, b . Slip assembly  710  is also suspended within annulus  711  by at least two leaf springs  712  in frictional relation with the inner wall  714  of tubular member  741  and the outer surface  742  of slip assembly  710 . The expansion apparatus  705  is then energized at a predetermined location opposite the slip assembly  710 . As the apparatus  705  is moved upwards in the well and rotated, the rollers  715  extend outwards in a gradually increasing manner, thereby forming a cone  730  that is slanted in the direction of the slip assembly  710 . After the expansion apparatus  705  is de-energized and removed, the liner hanger  700  is set by lowering the body  702  in relation to the stationary slip assembly  710 . Due to the absence of a cone formed on the liner hanger at the time of run-in, the tool of this embodiment has a reduced outer diameter and may be passed through a smaller annular area than prior art liners having a cone. While in the preferred embodiment the cone is formed in the direction of the well surface, it will be understood that the formation of a continuous expanded diameter can be made in any direction 
     In yet another embodiment of the invention depicted in FIG. 8, a first smaller diameter tubular  802  is expanded directly into engagement with the inner surface  805  of a larger diameter tubular  807 . In this embodiment, the expansion apparatus includes a roller capable of extending the wall of the first tubular  802  the entire width of the annular area  820  between the two tubulars  802 ,  807 . In the preferred embodiment, that portion of smaller diameter tubular  802  to be expanded into contact with the outer tubular, includes teeth  825  formed thereupon or some other means to increase grip between surfaces. 
     In another embodiment of the invention shown in FIGS. 9 and 10, a series of helical grooves  902  are formed in a wall  904  of a tubular member  906  through the use of an expanding member having rollers mounted in a helical fashion as shown in FIG.  9 . Specifically, the expansion apparatus  900  includes expandable rollers  908  that extend around the circumference thereof in a helix. The rollers  908  are constructed and arranged to extend outward as the apparatus is energized so as to come into contact with and exert a radial force upon the inside wall  910  of a tubular member  906 . As the expansion apparatus  900  is rotated and moved in an axial direction, a helical formation is left on the inner  910  and outer  912  walls of the tubular member  906 . This embodiment is particularly advantageous for making a connection between two pieces of casing in a manner that provides channels for the subsequent flow of drilling fluid or cement. The angle and depth of the helical grooves is variable depending upon well conditions and will be determined somewhat by the size of the annular area between two pieces of tubing to be joined together. In the embodiment described, rollers are used as the point of contact between the expansion apparatus and the tubular wall. However, the shape and configuration of the expansion apparatus members contacting and exerting a radial force upon the wall of tubulars in this and any other embodiment herein are not limited. 
     FIG. 11 demonstrates yet another method of expanding a tubular downhole. A non-collapsible mechanical packer  950  is located at a first location in the well and below that packer are various strings of tubulars including solid tubing  952 , slotted liner  954  and sand screen  956 . An expansion apparatus may be inserted into the well through the reduced diameter of the mechanical packer  950  and the various tubulars may then be selectively expanded. Thereafter, the apparatus can then be removed from the well without damaging the mechanical packer. 
     While the foregoing is directed to the preferred embodiment of the present invention, other and further embodiments of the invention may be devised without departing from the basis scope thereof, and the scope thereof is determined by the claims that follow.

Summary:
Methods, apparatus and tools to be used with tubular expansion apparatus. In one aspect of the invention, tools are actuated or operated within a well by selectively expanding the tool wall. To actuate the tool, the tool wall is urged outward past its elastic limits. The expanding wall physically unlocks a locking ring which then unlocks a piston. Thereafter, hydraulic pressure differences are employed to move the piston to operate the downhole tool. In another aspect of the invention, a first piece of casing is joined to a second, larger diameter casing. By expanding the diameter of the first piece of casing into contact with the second piece of casing, the two are joined together. The joint is formed with helical formations in a manner that provides flow paths around the intersection of the two members for the passage of cement or other fluid.