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BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates generally to inserting or running wellbore tubulars into a wellbore and, more particularly, to a collar load support system for picking up and lowering a wide size range of wellbore tubulars into the wellbore.  
           [0003]    2. Description of the Background  
           [0004]    Corrosion resistant alloy is useful in wellbore tubulars including casing, production tubing, and the like, to avoid premature failure of the wellbore tubulars in hostile environments. Severe corrosive action may occur in hostile environments such as deep, high pressure gas wells. Although such wells may be highly productive, they also tend to be expensive to drill and to workover. Therefore, these wells are suitable for extra precautions taken to extend the productive life thereof such as corrosion resistant alloy wellbore tubulars. Traditional procedures and hardware used to carry out installation of tubing may produce marks on corrosion resistant alloy wellbore tubulars because traditional procedures rely on toothed inserts or dies and gripping mechanisms that force the die or insert teeth radially inwardly against the pipe outer diameter. Ideally, complete elimination of the injurious die marks and associated necessary cold working for such tubulars would permit optimum performance of the corrosion resistant alloy, minimum cost of a string of corrosion resistant alloy, and the least weight thereof.  
           [0005]    One wellbore tubular running system, which is disclosed in U.S. Pat. No. 5,083,356, issued Jan. 28, 1992, to Gonzalez et al., and which is incorporated herein by reference, teaches a method for non-abrasively running tubing. The method includes the steps of suspending the tubing from the face of the uppermost collar of the tubing by resting the face upon a support shoulder, making up a new tubular with a collar into a tubular unit, attaching a non-abrasive lift unit to a tubular unit, stabbing the new tubular into the upper collar, non-abrasively making the connection tight, and lifting the unit to raise the string.  
           [0006]    The above wellbore tubular running system makes use of a shock table and landing spear that has several purposes. The landing spear engages the lifting unit, or load transfer sleeve, and is supported by the shock table. One of the purposes of the shock table is to reduce the dynamic effects of decelerating the tubing string. This deceleration occurs when the wellbore tubular string weight is transferred from the elevator to the shock table through a landing spear. If desired, the table compression rate may be provided in two stages although one stage could also be used. For example only of a two-stage system, from 0 to 60 tons, the load could be absorbed at a rate of 17.5 tons/inch and once the loading exceeds 60 tons, the compression rate could increase to 55 tons/in of deflection. Mechanical stops could be finally engaged at 160 tons. Essentially, the table compression rate increases the time span over which the load is applied regardless of the specific spring rates, the final mechanical stop and whether or not more than one stage of table compression rate is provided. The increased time interval significantly decreases the dynamic forces applied to the tubular coupling face as taught by the method.  
           [0007]    One of the problems of the above wellbore tubular system is that, for practical purposes, the system is limited in the size of the wellbore tubulars, including variable size items in the tubular string, which can be readily inserted into the wellbore. It would be desirable to provide means that can be used that would allow couplings and other large items to pass through the shock table and landing spear with ease while still maintaining full functioning of the shock table and landing spear. Another problem of the wellbore tubular running system relates to the shock table and the amount of space it takes up thereby requiring personnel to work on elevated work platforms, scaffolding, and the like in the midst of rather heavy equipment. Working on elevated work platforms tends to be more confining, more prone to slow downs, with less room for personnel to avoid accidents.  
           [0008]    Consequently, the above referenced prior art does not disclose means for eliminating the problems associated with existing non-abrasive wellbore tubular running systems. It would be desirable to provide a system suitable for running corrosion resistant alloy wellbore tubulars that permits more space on the rig floor. It would be highly desirable to allow the personnel to work on the rig floor rather than on scaffolding. As well, it would be desirable to provide such a system that is more flexible with respect to variations in wellbore tubular sizes, including casing, and permits couplings and large items to pass through the shock table and landing spear easily. Those skilled in the art have long sought and will appreciate the present invention which addresses these and other problems.  
         SUMMARY OF THE INVENTION  
         [0009]    The present invention was designed to provide more efficient operation to thereby improve flexibility of operation and to reduce drilling costs due to decreased time required for using different size wellbore tubulars, collars, and pipe string components.  
           [0010]    Therefore, it is an object of the present invention to provide an improved handling system for holding and lowering wellbore tubulars, especially a wide range of tubulars including pipes, production tubing, as well as large tubulars such as casing.  
           [0011]    Another object of the present invention is to provide a handling system that is easier to operate and is safer for rig personnel.  
           [0012]    A feature of the present invention is a split sectioned landing spear for which may be split open to allow a large item to easily pass.  
           [0013]    These and other objects, features, and advantages of the present invention will become apparent from the drawings, the descriptions given herein, and the appended claims. However, the invention is not limited to these objects, features, and advantages.  
           [0014]    Therefore, the present invention provides for a handling system for holding and lowering wellbore tubulars for use with a rig having a traveling block and a rig floor. The rig floor defines an opening therethrough for the wellbore tubulars. A plurality of collars is provided for interconnecting the wellbore tubulars. The system comprises a sleeve for engaging the plurality of collars and a landing spear for engaging the sleeve. A shock table is provided with a shock table body. A portion of the shock table body extends through the rig floor within the opening. The shock table comprises a compressible section with a compressible surface supported by the compressible section. The compressible surface supports the landing spear.  
           [0015]    In a preferred embodiment, a radially outwardly extending member is secured to one end of the shock table body for engagement with the rig floor and for supporting the shock table within the opening. The radially outwardly extending member may preferably be a flange.  
           [0016]    The landing spear is preferably pivotally mounted with respect to the compressible surface. The landing spear may comprise separable elements, wherein each of the separable elements may be pivotally mountable with respect to the compression surface. The landing spear has a base for engagement with the compression surface and may have a conical profile in one embodiment. The landing spear has an outer circumference and may be split into at least two sections with each of the two sections forming a portion of the outer circumference. A connection may be provided between the at least two sections and the compression table. The connection may be a pivotal connection to permit pivotal movement between the at least two sections and the compression table.  
           [0017]    In one method of the present invention, steps are provided such as mounting a shock table within the opening in the rig floor such that a substantial portion of the shock table is below a surface of the rig floor. Other steps may include providing a landing spear for receiving a weight of the wellbore tubulars and providing a compressible surface for the shock table such that the compressible surface is moveable with respect to the rig floor in response to tension applied thereto through the landing spear. In one embodiment, a step is provided for pivotally interconnecting the landing spear with respect to the shock table.  
           [0018]    In other words, one embodiment of the invention may include a shock table mountable with respect to the rig floor and a landing spear for supporting a weight of the wellbore tubulars transferred to the landing spear through the load transfer sleeve from respective of the plurality of collars. The landing spear may have at least two sections with each of the sections secured to the shock table by one or more connections that allow each of the sections to be moveable with respect to the shock table between a closed position and an open position. One or more of the connections may further comprise one or more hinges.  
           [0019]    In operation, one embodiment of a method for a handling system for wellbore tubulars may provide steps such as the step of suspending a wellbore tubular string by supporting a weight of the wellbore tubular string on a load transfer sleeve that engages a downward face of an upper collar of the wellbore tubular string wherein the weight of the wellbore tubular string may be received by a landing spear. The landing spear preferably has two or more landing spear sections. Additional operational steps may include lifting an additional wellbore tubular via a load transfer sleeve for attachment to the wellbore tubular string, stabbing a pin end of the additional wellbore tubular into the upper collar, making the pin end and the upper collar connection tight, lifting the wellbore tubular string, and opening the landing spear by moving the landing spear sections radially outwardly with respect to the wellbore tubular string.  
           [0020]    The method of operation may include compressing a compressible support surface in response to the weight of the wellbore tubular string at a selected rate of compression and pivotally attaching the landing spear with respect to the compressible support surface. In a preferred embodiment, the method further comprises mounting a shock table body for supporting the compressible support surface such that at least a portion of the shock table body is mounted beneath a rig floor.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0021]    [0021]FIG. 1 is an elevational view, partially in section, of a shock table mounted within a rig floor and a load transfer sleeve used for lifting wellbore tubulars;  
         [0022]    [0022]FIG. 2 is an elevational view, partially in section, of the wellbore tubular of FIG. 1 being stabbed into the tubular string;  
         [0023]    [0023]FIG. 3 is an elevational view, partially in section, of the elevator lowered over the wellbore tubular of FIG. 1 which has been made up into the wellbore tubular string;  
         [0024]    [0024]FIG. 3A is an elevational view, partially in section, of a hinged elevator lowered over the wellbore tubular of FIG. 1;  
         [0025]    [0025]FIG. 4 is an elevational view, partially in section, of the landing spear separated and the string lowered into the wellbore;  
         [0026]    [0026]FIG. 4A is an elevational view, partially in section, of the view of FIG. 4 using a hinged elevator;  
         [0027]    [0027]FIG. 5 is an elevational view, partially in section, of the landing spear being closed and the string being landed on the shock table; and  
         [0028]    [0028]FIG. 5A is an elevational view, partially in section, of the view of FIG. 5 using a hinged elevator. 
     
    
       [0029]    While the present invention will be described in connection with the presently preferred embodiments, it will be understood that it is not intended to limit the invention to those embodiments. On the contrary, it is intended to cover all alternatives, modifications, and equivalents included within the spirit of the invention.  
       DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0030]    Referring now to the drawings, and more specifically to FIG. 1, there is shown shock table  10  mounted within rig floor  12 . In one preferred embodiment, shock table  10  may be positioned within the rotary table in the position of the rotary table master bushing. Shock table  10  includes a radially outwardly extending member such as flange  14  which extends radially outwardly from shock table body  16 . Flange  14  engages an upper surface  18  of rig floor  12  thereby preventing further downward movement of shock table  10  with respect to rig floor  12 .  
         [0031]    Support platform  20  is moveable within shock table body  16  upwardly and downwardly. As shown in FIG. 1, support platform  20  is in a compressed position such that it has moved downwardly with respect to rig floor  12  due to the weight of wellbore tubular string  24 . Directions such as upwardly, downwardly, outwardly, and the like are intended to provide easy understanding of the invention with respect to the attached figures and should not be construed in any way as limiting the invention. It will be understood that various relative positions of the components may be used during transportation, assembly and the like. Compression platform  20  is preferably but not necessarily circular and preferably is guided by a corresponding cylindrical interior of shock table body  16 . Compression platform  20  defines bore  22  therein for receiving wellbore tubular string  24  therethrough. Body  16  preferably has a lower support surface  26  which also defines a bore  28  therethrough for receiving wellbore tubular string  24 . Compressible section  31  is contained within body  16  and lower support surface  26 . Compressible section  31  may comprise cylinders such as independent elastomer cylinders or other types of compressible cylinders to provide a spring-like effect. Compressible section  31  engages compression platform  20  and is compressed as compression platform  20  moves downwardly within body  16 . In a presently preferred embodiment, compression section  31  be designed to provide a constant compression rate for decreasing dynamic forces. However if desired, a two-stage compression rate for decreasing dynamic forces could also be used.  
         [0032]    Landing spear  30  is supported by compression platform  20 . Landing spear  30  engages load transfer sleeve  32  which engages the lower face  36  of coupling  34 . Lower face  36  and load transfer sleeve  32  support the weight of wellbore tubular string  24 . A second load transfer sleeve  32 A is attached to wellbore tubular  38  and engages the face of collar  40  as wellbore tubular  38  is lifted. Pick-up line  42  attaches to hanger  44  for lifting tubular  38  onto rig floor  12 . Tubular  38  may rest on V-door  37  which leads to rig floor  12  from the rig catwalk.  
         [0033]    In FIG. 2, wellbore tubular  38  has been raised above rig floor  12  so that the threads of pin  46  may be stabbed into and threadably connected to collar  34 . In this way, each wellbore tubular  38  is made part of wellbore tubular string  24 . FIG. 2 also shows another subsequent wellbore tubular  48  available for attachment to wellbore tubular string  24 . Therefore, wellbore tubular string  24  may, if desired, be run into the wellbore one joint at a time. Thus, FIG. 2 discloses a step in the operation of the present invention.  
         [0034]    Referring to FIG. 3, once wellbore tubular  38  is secured to wellbore tubular string  24 , then elevator  50  may be lowered over wellbore tubular  38 . Elevator  50  is secured to the traveling block of the rig by bails  52 . Hanger  44  preferably includes a plug section  54  that insertably engages collar  40 . Load transfer sleeve  32 A may drop down away from collar  40  during this stage of operation as shown in FIG. 3 after pick-up line  42  is disconnected from hanger  44  but remains supported by slings  56  attached to hanger  44 . Top guide  58  and leveling beam  60  are used to guide load transfer sleeve  32 A into elevator slips  62  for lifting wellbore tubular string  24  which now includes tubular  38 .  
         [0035]    In one embodiment, slips  62  are lowered into elevator body  50  creating inwardly radial movement of slips  62  to define a continuous load shoulder  63  as indicated in FIG. 4. As the driller lifts the traveling blocks, load transfer sleeve  32 A is pulled into engagement with slips  62 . Load transfer sleeve  32 A moves upwardly with elevator  50  until it stops at lower face  64  of collar  40 . As elevator  50  continues upward movement, the weight of wellbore tubular string  24  is now completely supported by elevators  50  through load transfer sleeve  32 A engagement with lower face  64  of collar  40  so that wellbore tubular string  24  also moves upwardly. Compressible section  31  therefore also moves compression support  20  upwardly to the uncompressed position as shown in FIG. 4 from the compressed position as shown in FIGS.  1 - 3 . Load transfer sleeve  32  may now be removed from wellbore tubular string  24  and secured to the next wellbore tubular such as wellbore tubular  48  which may be positioned on V-door  37 . Load transfer sleeve  32  may preferably include hinge and latch mechanism  66  for attachment and removal of load transfer sleeve  32 . Load transfer sleeve  32  is closely matched to the O.D. of the wellbore tubular to which it is attached such as wellbore tubular  48 . The I.D. of load transfer sleeve  32  may be elastomer coated to prevent impact damage to the pipe body during installation on a pipe such as production tubing or casing. Preferably no radial loads are supported by hinge and latch mechanism  66  while wellbore tubular string  24  is supported by load transfer sleeve  32 .  
         [0036]    In a preferred embodiment, landing spear  30  is split into at least two sections  68  and  70  and are mounted to thereby open up or rotate with respect to each other such as by pivotal connections or hinges  72  and  74 , respectively. In one presently preferred embodiment, hinges  72  and  74  are mounted to compression table  20 . Because landing spear  30  opens up, larger collars, joints, valves, and the like are easily accommodated through landing spear  30  and shock table  10  in accord with the present invention. When sections  68  and  70  are closed, landing spear engagement ends  76  and  78  may engage the load transfer sleeve such as load transfer sleeve  32 A. Base surfaces  80  and  82  are securely supported on compression table  20  when landing spear  30  is closed. While pivotal joints are preferred for automatic alignment purposes with the load transfer sleeve, other means for separating landing spear  30  could also be used such as slides, grooves, or the like. Preferably other separating means will also provide alignment with the load transfer sleeve when landing spear  30  is closed such as grooves, stops, or the like for quick and accurate alignment purposes. Pivotal joints or hinges may be provided between sections of landing spear  30  rather than between the shock table and the landing spear sections. Other types of connections could be used. The basic concept is that landing spear  30  moves or opens in some manner between a closed position wherein landing spear  30  is oriented and arranged to support the transfer sleeve and an open position wherein the landing spear sections are moved in such a way that large components can pass through landing spear  30  and shock table  10 . Thus, the landing spear is not a restriction that limits the O.D. of items to pass through shock table  10 . In one embodiment of the invention, load transfer sleeve  32  includes a counterbore (not shown) on the bottom side with sloping guide surfaces leading to the counterbore. The sloping guide surfaces lead direct ends  76  and  78  of landing spear  30  into the counterbore and thereby holds landing spear halves  68  and  70  together.  
         [0037]    During the next phase of operation, landing spear  30  is closed, such as by pivoting the sections thereof, and elevators  50  are lowered so that the weight or load is transferred from elevators  50  to landing spear  30  via load transfer sleeve  32 A as shown in FIG. 5. Upon receipt of weight of wellbore tubular string  24 , landing spear  30  applies the weight to compression table  20 , and compressible section  31  is compressed at the desired rate of compression for limiting dynamic forces. Elevator  50  may then release load transfer sleeve  32 A and be raised upwardly. Hanger  44  and related slings  56  are removed, or set aside while still attached to load transfer sleeve  32 A and the situation is the same as shown in FIG. 1. Another hanger  90  may be used with pick up line  42  for pulling the next joint of wellbore tubulars onto rig floor  12  for connection with wellbore tubular string  24 .  
         [0038]    In another embodiment of the invention as shown in FIG. 3A, elevator  50 A is used and is a type of elevator that is opened for operation such as with hinges  102  and latches  104  rather than using slips  62  as does slip type elevator  50 . However, such elevators are intended to include any elevator that opens to form an opening therein such as with a moveable door or panel but not necessarily limited to center latch elevators and side door elevators. A load shoulder  106  is incorporated into the inner profile of elevator  50 A. In a presently preferred embodiment of the invention, guide funnel  92  is provided to assist in guiding the load transfer collar, such as load transfer collar  32 A onto load shoulder  106 . In the open position, elevator  50 A is preferably lowered past load transfer sleeve  32 A as indicated. Lowering elevator  50 A to this position may sometimes require that bails  52  from which elevator  50 A is suspended be pivoted to provide clearance between elevator  50 A and load transfer sleeve  32 A and/or hanger assembly  44  which rests on wellbore tubular  38 . Once elevator  50 A is lowered to this position, then elevator  50 A is hinged shut so as to be ready to be lifted into engagement with load transfer sleeve  32 A.  
         [0039]    In FIG. 4A, load shoulder  106  has engaged load transfer sleeve  32 A and takes on the weight of wellbore tubular string  24  as discussed hereinbefore. Load transfer sleeve  32  can be removed and, if desired, placed on tubular  48  in accordance with the method of the invention. Landing spear  30  is moved as indicated in FIG. 4A such as by pivoting or sliding or in any other suitable manner to permit passage of elements including collars and/or any other radially enlarged elements through rotary table  12 .  
         [0040]    After tubular string  24  has been landed on landing spear  30  as shown in FIG. 5A and as discussed hereinbefore, then elevator  50 A is opened such as by unlatching and hingably or pivotally moving the side door or other opening member. In this way, load transfer sleeve  32 A can be disengaged from load shoulder  106  within elevator  50 A such as by swinging or pivoting bails  52  and then lifting the traveling block, bails  52 , and elevator  50 A past or above load transfer sleeve  32 A. Load transfer sleeve  32 A secures tubular string  24  by engaging landing spear  30 .  
         [0041]    Thus the present invention provides shock table  10  that is designed for mounting within the rig floor or rotary table so as to be largely out of the way. The shock table limits dynamic forces acting on the lower face of the coupling. The shock table may also provide a more accurately level surface of compression support  20  due to numerous compression cylinders for even spreading of forces. Landing spear  30  in accord with the present invention preferably opens easily to permit various size objects through the shock table. In a preferred embodiment, landing spear sections  68  and  70  are pivotally mounted to compression table  20  for easy opening as well as accurate and fast alignment with wellbore tubular string  24  and the corresponding load transfer sleeve such as load transfer sleeve  32  or  32 A.  
         [0042]    [0042]FIG. 6 and FIG. 7 show another advantage of the present invention regarding the ability to easily accommodate control and/or data lines  110  which may be run alongside tubular string  24  to various downhole devices (not shown). Such downhole devices may be used to gather data and/or to control well functions. The handling system of the present invention allows control/data lines to be lowered downhole through slot  112  which provides access to rotary opening  16 . Opening spear halves  68  and  70  provides means to attach control/data lines  10  to tubular string  24  using a plurality of clamps  108 . FIG. 6 shows a top view of the shock table with spear halves  68  and  70  open to provide a convenient means for attaching clamps such as clamp  108 . In FIG. 7 the spear halves are closed with load transfer sleeve  34  supporting tubular string  24 . Control and/or data lines  110  are in slotted opening  112 .  
         [0043]    While the method is directed to inserting or running wellbore tubulars into the wellbore, the same method and equipment could be used, if desired, to remove wellbore tubulars from the wellbore, install or remove stands comprising multiple tubulars connected as a unit rather than single joints, or other variations of operation. Removing tubulars involves the reverse of the process discussed hereinbefore.  
         [0044]    The foregoing disclosure and description of the invention is illustrative and explanatory thereof, and it will be appreciated by those skilled in the art, that various changes in the size, shape and materials, or the use of mechanical equivalents, or variations in the details of the illustrated construction or combinations of features of the invention may be made without departing from the basic concepts and/or spirit of the invention.

Summary:
A wellbore tubular handling system and method is provided for operation in holding and lowering tubulars, such as tubing strings, casing strings, pipe strings, and the various components thereof, at a rig site. The handling system utilizes a shock table with a compressible support surface that compressively moves with a selected compression rate in response to the weight of the wellbore tubular string. The shock table preferably has a shock table body mounted below the rig floor and may conveniently replace the rotary table master bushing except for a flange which supports the shock table on the rig floor. A split-sectioned landing spear can be split open to an open position to thereby allow large items such as collars or other string components to pass through the shock table. In a closed position, the landing spear supports, preferably indirectly, an upper collar of the wellbore tubular string to thereby support the weight of the wellbore tubular string and apply the weight to the compressible support surface of the shock table.