Abstract:
Expanding packers for use in oil or gas wellbores, with and without casing, for isolating a casing annulus or geologic formation from the remainder of the wellbore and for increasing production flow rates. These expanding packers are useful in completing sidetracked wells.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to apparatus and methods for drilling and/or completing wells in the subterranean. In another aspect, the present invention relates to apparatus and methods for isolating geological formations in wells and isolating well casing annuluses. In even another aspect, the present invention relates to apparatus and methods for producing from side tracked wells drilled from the bore of previously drilled wells. In still another aspect, the present invention relates to apparatus and methods for isolating defective casing in an existing wellbore, isolating a liner top, or isolating a zone. 
     2. Description of the Related Art 
     Oil fields are usually produced by drilling wells to one or more large reservoirs or to vertically-separated smaller reservoirs encountered by an individual wellbore. The costs of a well are the costs of drilling and the cost of completion. Whereas drilling is the actual creation of the wellbore, completion is the process of inserting casing, tubing, and tubular accessories into the well to allow the oil or gas to be drawn out and stored for use. It is common practice in completing a well to run a string of protective casing into the wellbore and then to run production tubing inside the casing to one large reservoir or to vertically-separated production zones encountered by the wellbore. Once the oil or gas bearing formations penetrated are depleted, the well has lost its usefulness. 
     In many instances, small reservoirs in other areas of the oil bearing formation in the vicinity of the wellbores may not be depleted. Unfortunately, it is expensive to drill out through the side of the well (sidetrack) through the existing well casing using conventional sidetracking methods. Such methods require that the tubing be removed, a section of the casing be milled out and a drill run back down through the casing and directed outward through the milled-out section to drill a directional well from the casing outwardly to an area from which additional hydrocarbons may be recovered. Since these techniques are relatively expensive, the amount of potential hydrocarbon recovery required to justify such sidetracking operations is relatively large. Since, in many instances, areas of potentially recoverable hydrocarbons containing less than the amount required to justify this additional expense are known, it is desirable that a more economical method be developed to enable the economical recovery of these smaller quantities of hydrocarbons. The smaller quantities of hydrocarbons may, in fact, be quite sizeable. 
     One problem that can reduce the cost effectiveness of a side tracked well is that the new tubing inserted in the original well casing in the process of drilling the lateral well usually is of smaller diameter than the tubing of the original well to provide room for passing the tubing down the casing and into the lateral wellbore. This smaller diameter of tubing reduces the rate at which oil or gas can be brought to the surface. 
     Another problem associated with conventional sidetracking methods is the frequent need to run and cement an additional set of casing above or through the proposed producing formation to isolate the side tracked well from such problems as adjacent water-bearing formations. 
     There is a need in the art for apparatus and method for drilling and/or completing a well. 
     There is another need in the art for improved apparatus and methods for drilling and/or completing a well, which do not suffer from all of the deficiencies of the prior art. 
     There is even another need for apparatus and methods for performing cost-effective side tracked well completions. 
     There is still another need in the art for apparatus and methods for accessing small reservoirs with side tracked completions, which do not suffer from the disadvantages of the prior art apparatus and methods, such as the need to run and cement an additional set of casing above or through the proposed producing formation. 
     There is yet another need in the art for apparatus and methods for isolating formations and well casing annuluses. 
     There is even still another need in the art for apparatus and methods for isolating formations and well casing annuluses which address at least some of the deficiencies of the prior art, such as obtaining reduced flow rates because of the necessity of running smaller tubular strings to operate within existing wells. 
     These and other needs in the art will become apparent to those of skill in the art upon review of this specification, including its drawings and claims. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide for an improved apparatus and method for drilling and/or completing a well. 
     It is another object of the present invention to provide for apparatus and methods for performing cost-effective side tracked well completions. 
     It is even another object of the present invention to provide for apparatus and methods for accessing small reservoirs with side tracked completions, which do not suffer from the disadvantages of the prior art apparatus and methods, such as the need to run and cement an additional set of casing above or through the proposed producing formation. It is an object of the present invention to provide for apparatus and methods for isolating formations and well casing annuluses. 
     It is still another object of the present invention to provide for apparatus and methods for isolating formations and well casing annuluses which address at least some of the deficiencies of the prior art, such as obtaining reduced flow rates because of the necessity of running smaller tubular strings to operate within existing wells. 
     These and other objects of the present invention will become apparent to those of skill in the art upon review of this specification, including its drawings and claims. 
     According to one embodiment of the present invention, there is provided a packer system which generally includes an expandable tubing and at least one elastomeric expanding element encircling said tubing. In a more specific non-limiting embodiment of this embodiment, the expandable packer system includes expandable tubing with separated transverse external bands of elastomeric elements adhering to the tubing with each of the two transverse edges of each band anchored by single centralizer rings, which also serve to maintain a packer in the center of a wellbore or casing. 
     According to another embodiment of the present invention, there is provided a work string assembly for use in a subterranean wellbore. The assembly generally includes a work string suitable for insertion into the wellbore. The work string also includes a pig launcher connected to the work string. The work string even also includes an expandable tubing connected to the pig launcher and at least one elastomeric expanding element encircling said tubing. 
     According to even another embodiment of the present invention, there is provided a method for expanding a packer in a well. The method generally includes positioning a packer system, as described above, in a subterranean well, and then passing an expansion pig through the expandable tubing to abut the elastomeric elements against the well wall. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1A is an illustration showing drilling rig  240  at the Earth&#39;s surface  250  to which are attached casing  105  and tubing  102  inside of casing  105 , whipstock  135  positioned at the bottom end of casing  105  just above casing opening  122  to open hole  125 . 
     FIG. 1B is an enlarged illustration of expanding packer  200  of FIG.  1 A. 
     FIG. 2 is an illustration of the apparatus and methods used to produce oil or natural gas from a side tracked well that is unlined with casing. Shown is expanding packer  200  after expansion and several expanding elements  135  in contact with the walls of side tracked well  125 . 
     FIG. 3 is a cross section of expanding packer  200  showing expandable tubing  120  with elastomeric element  210  molded completely around expandable tubing  120 . 
     FIG. 4 is a side view of expanding packer  200  designed to be used in well applications where there is no casing lining the well. 
     FIG. 5 is a side view of expanding packer  300  designed for use in wells that have previously been lined with casing. 
     FIG. 6 is a side view of expansion pig  260  that can be passed through expandable packers  200  and  300  to expand them. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring first to FIG. 1A, there is shown an illustration of a typical drilling rig  240  on the Earth&#39;s surface that can be used to insert expandable tubing  102  inside casing  105 . 
     Referring additionally to FIG. 1B, there is shown an illustration of the apparatus and method for using expanding packer  200  attached at its upper end to running assembly  112 , and attached at its lower end to screen  130 . 
     In the practice of the present invention, the expanding packer will comprise one or more expanding elastomeric element, which encircle the expandable tubing, with each of the one or more elastomeric elements being the same or different widths, and with the various spacings between adjacent elastomeric elements being the same or different. 
     For example, in the embodiment of expanding packer  200  as shown FIGS. 1 and 2, expanding packer  200  comprises three expanding elastomeric sealing elements  115  encircling expandable tubing  120 . Elements  115  will serve to seal the annular space between tubing  120  and the wall of open hole  125 , upon expansion of tubing  120 . 
     While expanding packer  200  comprises elastomeric expanding sealing elements  115  illustrated as being about the same width  115 B (along the length of tubing  120 ) it should be understood that they may be of different widths  115 B. Additionally, while the spacings  115 A between adjacent sealing elements  115  are shown as being about equal, it should be understood that they may be different. 
     The height  115 C and width  115 B of expandable elastomeric sealing elements  115  are selected to provide suitable sealing characteristics between tubing  120  and the wall of open hole  125 . Without being limited by theory, it is believed that height  115 C and width  115 B will be a function of the type of material selected for element  115 , the contour of open hole  125 , the geology of hole  125 , down hole environment, and the amount of expansion of tubing  120 . 
     In the practice of the present invention, it is most important that, the material of element  115 , width  115 B, and height  115 C, be selected such that element  115  remains sufficiently intact after expansion of tubing  120  to substantially form a seal in the annular space between tubing  120  and the wall of open hole  125 . 
     Where there are two or more elements  115 , they may be spaced at various intervals along the length of the packer, with the various spacings between adjacent elements  115  being the same or different. Elastomeric expanding elements  115  may be made of any suitable material, provided that the desired amount of expansion and sealing is obtained. Suitable materials may include metals, thermoplastics, thermosets, composites, and the like. Non-limiting commercial examples of suitable materials include nitrile, viton, fluorel, aflas, and teflon. 
     Running assembly  112  is comprised of connector  110 , shown as polished bore receptacle  110 , and a pig launcher  145 . Positioned in casing  105  below lateral opening  122  is plug  140  which supports whipstock  135 , which serves to guide and direct packer  200  through opening  122  into open hole or side tracked well  125 . 
     The method of inserting expanding packer  200  into side tracked well  125  requires first ensuring, that the well bore fluid is conditioned, then attaching at the Earth&#39;s surface  250  a screen  130  to expanding packer  200 , which in turn is attached to running assembly  112 , which is then attached to the end of tubular work string  102  via the polished bore receptacle  110 . The sequence of insertion begins with screen  130  down existing well casing  105 , followed by expanding packer  200 , followed by running assembly  112 , finally followed by work string  102 . In more detail, screen  130  is pushed against whipstock  135 , which directs screen  130  followed by expanding packer  200  and the other attachments in sequence through opening  122  in casing  105  into side tracked well  125  and is extended to desired hole position  145 . Side tracked well  125  is described as open to indicate that it has not been previously lined with casing. 
     Referring next to FIG. 2, there is shown an illustration of the apparatus and method of production using expanding packer  200 . Once expanding packer  200  is positioned in side tracked well  125  as shown in FIG. 1B, an expansion pig  260  is launched from pig launcher  145  down the length of expanding packer  200  expanding it to press against the bare walls of side tracked well  125 . Separate expanding elements  115 , expanded by the expansion of packer  200 ,contact at intervals the walls of side tracked well  125 , holding expanding packer  200  in place and restricting and preferably preventing the flow of liquids through annular spaces  127  defined between expanded tubing  120 A and walls of side tracked well  125  and bounded by expanding elements  115 . 
     An alternative method of using an expansion pig to enlarge expanding packer  200  is to position the pig in the end of expanding packer  200  adjacent to screen  130 , prior to insertion downhole. Once screen  130  is positioned at desired hole position  145 , the pig can be directed to move back up expanding packer  200  and away from screen  130  to expand expanding packer  200 . Following that expansion, the pig can be removed from side tracked well  125 . 
     Once packer  200  has been expanded, tubular work string  102  is removed from casing  105 , production tubing  107  is then run down into well casing  105  and connected to expanding packer  200  via polished bore receptacle  110 . With annular space  127  between expanded casing  120 A and the wall of side tracked well  125  blocked, oil flowing into side tracked well  125  in the vicinity of screen  130  can be drawn through screen  130  up through expanding packer  200  and up production tubing  107  allowing recovery. Production tubing  107  may also be made of expandable tubing which, once expanded with a pig, will allow a greater rate of oil transport to occur in comparison to that achieved with un-expanded tubing. Also shown is an optional surface controlled subsurface valve  150  to allow shutting the well. 
     Referring next to FIG. 3, there is shown an illustration of expanding packer  200  in cross section with the elastomeric element illustrated as a molded elastomeric coating  210  adhering to the outer surface of expandable tubing  120 . 
     In the practice of the present invention, one or more fasteners may be utilized to restrict the relative linear movement between the elastomeric element and the tubing. Referring next to FIG. 4, there is shown a side view illustration of expanding packer  201 , another embodiment of the expanding packer of the present invention. In this embodiment, expanding packer  201  comprises only one expanding element  115 , and further comprises two fasteners  230 , illustrated as centralizers  230 , which are ring clamps at the ends of elastomeric coating  210  that restrict it from linear movement along tubing  120  when it is expanded to the walls of the side tracked well  125 . Of course, while fasteners  230  are shown affixed directly onto tubing  120  to restrict movement, it should be understood that fasteners  230  may also be positioned directly on elastomeric element  210  to bias it against tubing  120  and thereby restricting linear movement. 
     The methods and expanding packers  200  and  201  described above and illustrated in FIGS. 1,  2 ,  3 , and  4  eliminate the need to run and cement an additional set of casing above or through the proposed producing formation. Expanding packers  200  and  201  for open hole side tracked wells provide an effective method for annular isolation of a producing formation by preventing movement of liquids between the outer surface of expanding packer  200  and the inner surface of side tracked well  125 . 
     Referring now to FIG. 5, there is shown an illustration of expanding packer  300  for use in cased hole applications. The method of use of this expanding packer  300  in side tracked wells is the same as that described for expanding packer  200 , except that it is used in side tracked wells that have previously lined with casing. Expanding packer  300  is comprised of expandable tubing  120 , encircled at intervals with elastomeric element  340 , bounded on both ends by centralizer rings/expanding rings  310  which hold expanding c-ring slips  320 . All of the structures of expanding packer  300  are expandable as expandable tubing  120  is expanded by the passage of an expansion pig passing through it. The methods of expanding the expanding packer  300  are the same as those for expanding the expanding packer  200 , except that expanding packer  300  is positioned inside of prior casing in side tracked well  125  and elastomeric elements  340 , centralizer/expanding rings  310 , and expanding c-ring slips  320  serve to expand against the inner wall of casing and seal the space between expanding packer  300  and the surrounding casing of the well to prevent the flow of liquids in the annular space between expanding packer  300  and the casing of the well. 
     Expanding packers  200 ,  201  and  300  will also be useful in more conventional well completions. Expanding packers  200  and  201  for open hole applications may also be used to isolate bad casing in an existing wellbore, liner top isolation, and zonal isolation. Expanding packer, 300  for cased hole applications may also be used for the above applications along with use as a production sump packer, production packer, and liner hanger, with or without sealing element applications. 
     Referring now to FIG. 6, there is shown an a non-limiting example of a suitable expansion pig  260  that can be used to expand the expanding packers of the present invention by using liquid or gas pressure applied from drill rig  240  to force expansion pig  260  through the expanding packers from either their upper or lower ends. 
     While the illustrative embodiments of the invention have been described with particularity, it will be understood that various other modifications will be apparent to and can be readily made by those skilled in the art without departing from the spirit and scope of the invention. Accordingly, it is not intended that the scope of the claims appended hereto be limited to the examples and descriptions set forth herein but rather that the claims be construed as encompassing all the features of patentable novelty which reside in the present invention, including all features which would be treated as equivalents thereof by those skilled in the art to which this invention pertains.