Abstract:
A U-shaped elevator having no doors is provided with first and second latching mechanisms which when contacted by the tubular to be entrapped within the elevator move from a closed position to an open position and which then return to a closed position as soon as the tubular is entrapped within the elevator. The latching mechanisms have a safety catch which prevents the tubular from being inadvertently removed from the elevator. The safety latch mechanism can only be activated by a handle which is manipulated by hand by personnel working on the derrick utilizing the elevator. The elevator has an open throat to receive tubulars that have couplers or other features with a lower flange surface for lifting a pipe string. The throat access has blocking members that are movable to allow tubulars to move out of the gap unless the blocking members are locked to prevent such movement. The blocking members have latches biased toward a position to immobilize the members. To allow tubulars to exit the throat, an unlocking mechanism is actuated manually or by motorized means under remote control.

Description:
RELATED APPLICATION  
       [0001]    This application is a continuation-in-part of U.S. patent application Ser. No. 09/410,706, filed Oct. 1, 1999. 
     
    
     
       FIELD OF INVENTION  
         [0002]    The invention relates, generally, to pipe handling elevators used for lifting and lowering oilfield tubulars, usually as strings of pipe being tripped into or out of an oil or gas well.  
         BACKGROUND OF THE INVENTION  
         [0003]    It is well known in the art of drilling, completion and workover of earth boreholes in the oil, gas and geothermal industries to run strings of oilfield tubulars into and out of such boreholes, sometimes referred to as “tripping in” or “tripping out”. Such tubulars can be, for example, drill pipe, drill collars, casing and tubing. It is also well known to use elevators in such tripping in or out operations to lift or lower such tubulars out of, or into the wells. The handling gear for such tubulars is oftentimes much alike in principle for all sizes but the difference in scale is impressive. Well casing with a diameter of six feet, with a two inch wall thickness, is not uncommon.  
           [0004]    Elevators in the prior art typically are hinged, heavy clamps attached to a hook and traveling block by bail-like arms, sometimes referred to simply as “bails”. Such elevators oftentimes use one or more doors which are themselves quite heavy, and which may require two or three strong men to close or hinge the one or two doors around the tubular. Doors are a common feature but there are single door and split door types. One type simply hinges to open to admit or eject pipe. In hoisting ajoint of drill pipe, the elevators are latched onto the pipe just below the tooljoint (coupling) which prevents the drill pipe from slipping through the elevators.  
           [0005]    Similarly, in lifting casing or tubing, the sections of such tubulars have either an upset end, i.e., one in which the O.D. is larger than the primary diameter of the casing or tubing, or they are joined together with a collar having an enlarged O.D. In all of these type of operations, the elevator when hinged to the closed position, i.e., when the one or two doors are closed shut, the internal diameter of the elevator is less than the O.D. of the end of the enlarged tool joint, upset, or collar to prevent the tubular from slipping through the elevator.  
           [0006]    Handling practices differ between small and rather large diameter pipe. Each section of very large pipe will typically be picked up from the horizontal position and swung to the vertical for stabbing into the connection of the assembled tubular string. Such large pipe, for example, large diameter steel casing, presents special problems. When elevators are placed on the horizontal pipe they have to pivot to orient the elevator throat opening downward. That leaves the doors, on door-type elevators, swinging on hinges. The doors on a large elevator may weigh several hundred pounds. To close such doors, drilling crew men place themselves in hazardous situations. The rigging devised to get the doors closed often is creative, but risky.  
           [0007]    An elevator with doors needs clearance for the doors to swing in the closing arc under the pipe being engaged. The pipe has to be elevated, or clearance otherwise provided, for the swinging door.  
           [0008]    The elevators discussed above are of the so-called“non-slip” variety. There are other elevators which grasp the tubular and can be used to then hoist or lower the tubular, but the grasping elevators are typically used with the light weight tubulars.  
           [0009]    The elevators of the “non-slip” variety have generally been constructed with doors (generally, one or two) which open to allow the insertion or removal of the tubulars. These doors have traditionally been heavy, slow in operation, difficult to handle and present a considerable safety hazard to the operator. Also, the balance point of the elevator will change dramatically when the doors are opened, thus exacerbating handling problems and adding danger to the operator.  
           [0010]    Especially with very heavy tubulars, for example, 20″-30″ casing, the tubular is initially in a horizontal position, laying in place, for example, on or near the floor beneath a derrick, and the hinged door elevator is lowered near the point of attachment to the tubular. The derrick hands then are required to open the very heavy door or doors, which may weigh several hundred pounds, to allow the elevator to be placed over the tubular. Moreover, because the door or doors must close around the tubular, the tubular end around which the elevator is placed must be above the derrick floor.  
         SUMMARY OF THE INVENTION  
         [0011]    The present invention avoids the above mentioned shortcomings by eliminating the troublesome door members. Retention of the pipe is then accomplished by a system of multiple pipe catches, which are automatically deployed after the insertion of the pipe joint and which automatically retract during insertion of a pipe joint. Importantly, since this elevator lacks swinging doors, the element of the greatest safety concern is eliminated and, the equilibrium of the elevator is undisturbed during insertion or removal of pipe.  
           [0012]    When a tubular approaches the elevator, according to the present invention, the tubular first contacts the disconnector arms. As insertion continues, the disconnector arms are swung away in an arc-like path and this motion actuates the disconnector links which disengage the safety latches, allowing the pipe catches freedom to move. The continuing movement of the pipe into the elevator next causes the pipe to contact the pipe catches directly and pushes them out of the way against a nominal spring force. After the pipe is fully seated into the elevator, the pipe catches (no longer restrained by the pipe body) will automatically deploy by means of spring power. The pipe is now mechanically entrapped and cannot fall out of the elevator. As a function of the mechanism&#39;s geometry, the greater the force from the pipe resting against the catches, the greater will be the resistance to opening. The pipe catches, in effect, become self-energizing. In fact, it will not be possible to manually open the elevator if a side force against the catches is present. This feature is an additional safety benefit.  
           [0013]    In practicing the methods according to the present invention, elevators can be dropped or lowered onto a horizontal tubular, or swung against a vertical tubular to latch around the tubular, thus by avoiding all or most of the problems associated with using hinged door elevators.  
           [0014]    The present invention comprises a horseshoe, or “U” shaped body having first and second extending arms separated by a throat to accept a pipe or other tubular. On each arm a blocking member imposes into the passage to and from the throat and either blocking member will prevent pipe (within the elevator rating size) from moving out of the throat of the elevator. The blocking member is spring biased to the blocking, or closed state. In the closed state, a spring biased security lock goes to the locked state, and the blocking member is immobilized in the closed state. There are two ways to free the blocking member. One way is for pipe to be urged toward the throat where it engages an enabling lever which lifts the security lock and frees the blocking member to move to admit pipe to the throat. The second way to manipulate the blocking member is to activate a dumping lever which lifts the security lock and moves further to move the blocking member away from the throat to permit pipe to move out of the throat.  
           [0015]    The elevator has no structure that prevents the elevator from engaging pipe lying on a rig floor. The elevator freely pivots within the loops of bails which engage ears, one on each side of the body.  
           [0016]    Not all elevators are suspended from the traveling blocks by bails, the term used herein represents any of the many contrivances serving the equivalent function in suspending elevators from traveling blocks or the equivalent hoisting apparatus.  
           [0017]    In the preferred embodiment, and as a special feature of the invention, the ears are positioned such that the lift vector, originating at the transverse line about which the ears rotate within the bail loops, passes some distance from the centerline of pipe, when positioned for lifting, within the throat. With an open throat, the periphery of the ledge that engages the lifting surface of the pipe, normally the lower surface of a connector, represents an area that has a geometric center shifted toward the back of the throat. Ideally, but not in a limiting sense, the extended lift vector passes through, or near that geometric center.  
           [0018]    These and other objects, advantages, and features of this invention will be apparent to those skilled in the art from a consideration of this specification, including the attached claims and appended drawings. 
       
    
    
     BRIEF DESCRIPTION OF DRAWINGS  
       [0019]    For a further understanding of the nature and objects of the present invention, reference should be had to the following detailed description, taken in conjunction with the accompanying drawings, in which like elements are given the same or analogous reference numbers and wherein:  
         [0020]    [0020]FIG. 1 is a diagrammatic view of a prior art, oilfield tubular elevator;  
         [0021]    [0021]FIG. 2 is a diagrammatic view of a second prior art, oilfield tubular elevator;  
         [0022]    [0022]FIG. 3 is a top plan view of the elevator according to the present invention;.  
         [0023]    [0023]FIG. 4 is an expanded view of a latch mechanism used with the elevator illustrated in FIG. 3 according to the present invention;  
         [0024]    [0024]FIG. 5 is a series of top plan, sequential views of the elevator according to the invention, illustrating the manner in which the tubular is trapped inside the elevator;  
         [0025]    [0025]FIG. 6 is a top plan view of an elevator according to the present invention illustrating an additional feature of the invention;  
         [0026]    [0026]FIG. 7 is an enlarged top view of a portion of the elevator of FIG. 6 illustrating an alternative embodiment of the invention; and  
         [0027]    [0027]FIG. 8 is a sectional view taken along the section lines  8 - 8  of FIG. 7. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0028]    Referring now to the drawings in more detail, FIG. 1 ( a ) illustrates a top plan view of a hinged door elevator which is commonly used in the prior art. The prior art elevator  10  has a donut shaped body  12 , having a center orifice  14  for encircling a tubular  16  such as is illustrated in FIG. 1( c ). The elevator  10  has a pair of ears  18  and  20  having holes  19  and  21 , respectively, to which the bales (not illustrated) can be attached. The elevator  10  is quite thick, for example, 8 to 10 inches thick, to have the required strength for picking up tubular strings such as large well casing which weigh in the hundreds of thousands of pounds. The elevator  10  has a door  24  which is made to rotate about a pivot pin  26  to open or close the door  24 . As illustrated, the door  24  is in the closed position and is latched to the remainder of the elevator  10  to secure it into position. When the door  24  is to be opened to allow a tubular within the orifice  14  to be released, the door  24  is unlatched and pivoted around the pivot pin  26  as shown by the rotational arrow  28 .  
         [0029]    [0029]FIG. 1( b ) and  1 ( c ) , respectively, illustrate a top plan view of a tubular  16  to be entrapped within the elevator  10  and an elevated, partial view of the tubular  16 . The tubular  16  has an upset, enlarged end portion  30  having an outside diameter  32  as measured between the two lines  34  and  36 . The tubular  16  also has a primary section  40  below the upset portion  30  which has a reduced diameter as measured between the two lines  42  and  44 . The portion  40  of the tubular is sized to fit within the interior orifice  14  of the elevator  10  as illustrated in FIG. 1( a ). Whenever the door  24  is opened, the elevator  10  fits around the tubular  16  at a point along the tapered surface  50  of the tubular  16 . As is well known in the art, the tubular  16  also includes a passage  52  along its length for allowing drilling fluid or other fluids to pass therethrough when the tubular is in an earth borehole (not illustrated).  
         [0030]    In the operation of using the prior art elevator illustrated in FIG. 1, when it is desired to have the elevator  10  latch onto the tubular  16 , whether from the horizontal or vertical positions, the door  24  has to be opened to allow the remainder of the elevator  10  to latch onto the tubular  16  at a point just beneath the upset portion  30 . It should be appreciated that when the tubular is very heavy, for example 20″ to30″ heavy steel casing, the elevator  10  is quite large, weighing several hundred pounds, and it requires a great amount of human effort and exposure to safety hazards to open the door  24  and engage the tubular  16  with the elevator  10 .  
         [0031]    It should be appreciated that although FIG. 1( a ) illustrates a prior art elevator having a single door which pivots around a pivot pin  26 , the prior art also includes a pair of doors (not illustrated) which together accomplish somewhat the same function as the door  24 , but which are each only half the weight of a single door to allow the two doors to be opened and closed manually easier than a single door.  
         [0032]    Referring now to FIG. 2, there is illustrated another type of prior art elevator  60  which has no doors, but which depends upon the weight of the tubular being hoisted or lowered to maintain the tubular within the interior of the elevator  60 . This type of elevator  60  is typically used by those in the prior art to raise or lower much more light weight types of downhole pipe, such as solid sucker rods, hollow sucker rods and light weight tubing. Elevator  60  has a pair of attachment rods  64  and  66  around which bales can be pivoted thereabouts, allowing the bales to be attached to a hook and traveling block as discussed above with respect to the prior art elevator of FIG. 1.  
         [0033]    The light weight tubular  62  of FIG. 2 has an upset end  70  sized to ride on the top of the elevator  60  while the primary portion of the tubular  62  below the upset end portion  70  is sized to fit through the side opening  72  of the elevator  60 . This type of elevator is normally not used to handle the very heavy tubulars because of not having a means of entrapping the tubular within the elevator in a secure manner.  
         [0034]    Referring now to FIG. 3( a ), the elevator  100  is illustrated in this preferred mode of the invention as being essentially U-shaped, sometimes referred to as having a horseshoe shape. A first latching mechanism  102  and a second latch mechanism  104  are located, respectively, within the two arms  106  and  108  of the U-shaped elevator  100 . The two arms  106  and  108 , together with the arcuate end section  105  form the U-shape. A “stick figure” illustration of a human being  110 , which typically would be a rig hand working on the derrick in tripping the tubulars in or out, is illustrated as having his right hand on the elevator handle  112 . The latch mechanism  104  is illustrated as being in the open position, whereas the latch mechanism  102  is in a closed position, as will be explained in more detail with respect to FIG. 4, hereafter. Although explained in more detail with respect to FIG. 4 and FIG. 5, it should be appreciated that as the pipe or other tubular enters the open end of the horseshoe shaped elevator  100 , the tubular will contact the latching mechanisms  102  and  104 , causing both of them to assume the open position as shown in FIG. 3 for mechanism  104 . As the tubular proceeds further into the interior of the U-shaped elevator  100  the mechanisms  102  and  104  will return to the closed position as illustrated with respect to mechanism  102  of FIG. 3, thus entrapping the tubular within the interior of the elevator  100 .  
         [0035]    Referring now to FIG. 4, the enlarged view of the latch  102  is now described in greater detail. It should be appreciated that the latches  102  and  104  are in cut-outs in the sides of arms  106  and  108 , respectively, of the elevator  100 , and are not located on the top surface of the elevator  100 . The top surface of elevator  100  is sized to be smaller, in its internal diameter, than the external diameter of the upset end of the casing being raised or lowered.  
         [0036]    The latch mechanism  102  in FIG. 4 includes a disconnector arm  130  having a wear pad  154  which will be contacted first by the tubular to be entrapped. The arm  130  is pivotable about a pivot rod  132  which, as illustrated in FIG. 3( b ), traverses the width of arm  106 . A spring  149  encircles the pivot rod  132 , and has a first end  155  located against the back surface of the wear pad  154 , and a second end  151  located against the elevator handle  152  which is used merely to hand position the elevator  100 , if and when needed.  
         [0037]    A disconnector link  134  has a first end connected to the disconnector arm  130  and a second end connected to a safety latch plate  120 . The plate  120  has a recess  126  sized to receive a rod  124 , which as illustrated in FIG. 3( b ), traverses the width of arm  106 .  
         [0038]    Further in FIG. 4, the plate  126  is illustrated as being pivotable about a rod  122 , which has a spring  160  encircling the rod  122  and having a first end located against one end of the disconnector link  134  and a second end connected within a manual handle  170 . The handle  170  is illustrated as shorter than its actual length, which may be one to two feet long for case of operation.  
         [0039]    The tubular catch  131  is configured from a hard metal, for example, steel, and is thick enough and strong enough to withstand any forces exerted by the entrapped tubular, and has an arcuate lower surface  133  closely approximating the curvature of the entrapped tubular, for example, as illustrated in step  10  of FIG. 5. The catch  131  also pivots around the pivot rod  132 , and has a width closely approximating the width of the arm  106 .  
         [0040]    [0040]FIG. 3 also illustrates a bale attachment member  112 , one of which is attached to each of the arms  106  and  108 , allowing the elevator  100  to be used with a traveling block (not illustrated).  
         [0041]    In the operation of the latch mechanism  102  of FIG. 4, the latch is illustrated as being in the closed position, exactly the same position as if a tubular were trapped inside the elevator  100 . The latch mechanism  104  of FIG. 3, which is a mirror image of latch mechanism  102 , would also be in the closed position. As the tubular to be entrapped within the elevator approaches the elevator, the tubular first contacts the wear pads of the disconnector arms of the two latches  102  and  104 , (e.g., wear pad  154  of arm  130  of latch  102 ).  
         [0042]    As insertion continues, the disconnector arms are swung away in an arc-like path and this motion actuates the disconnector links which disengage the safety latches, e.g., plate  120 , allowing the pipe catches, e.g. catch  131 , freedom to move. The continuing movement of the pipe into the elevator next causes the pipe to contact the pipe catches directly and pushes them out of the way against a nominal spring force. After the pipe is fully seated into the elevator, the pipe catches (no longer restrained by the pipe body) will automatically deploy by means of spring power. The pipe is now mechanically trapped and cannot fall out of the elevator. As a function of the mechanism&#39;s geometry, the greater the force from the pipe resting against the catches, the greater will be the resistance to opening. The pipe catches, in effect, become self-energizing. In fact, it will not be possible to manually open the elevator if a side force against the catches is present. This feature is an additional safety benefit.  
         [0043]    It should be appreciated that as the tubular to be trapped within the elevator touches the disconnector arm such as arm  130  in FIG. 4, the disconnector link  134  causes the safety latch plate  120  to disengage from the rod  124 . As the tubular moves further past the catch  131 , the plate  120  swings into position such as is better illustrated for latch mechanism  104  in FIG. 3, which illustrates the disconnector link  134  as being essentially perpendicular to the longitudinal axis of the arm  108 . In that position, the latch  104  is in the open position and allows the tubular to be further inserted within the interior of the elevator  100 . As the tubular goes past the latch mechanisms  102  and  104 , the latch mechanisms  102  and  104  return to their closed position such as is illustrated by the latch mechanism  102  in FIG. 3.  
         [0044]    When the tubular which is entrapped within the elevator  100  is in a position which no longer requires the elevator  100  to be used, the handle  170  illustrated in FIG. 4 is rotated manually to return the latch mechanism  102  to its open position. The corresponding handle for latch mechanism  104  is similarly rotated, and with each of the latch mechanisms  102  and  104  in the open position, the elevator  100  is easily removed from the tubular.  
         [0045]    Thus, it should be appreciated that in utilizing the apparatus and method herein disclosed, whenever it is desired to attach the elevator according to the invention around a tubular, whenever the tubular is in a horizontal or near horizontal position, the only step required to attach the elevator to the tubular is to drop the elevator, or lower the elevator onto the tubular and the latching mechanisms herein described will entrap the tubular with no additional steps required. Such a method is illustrated by means of the sequential steps of FIG. 5 in which the elevator  100  is lowered onto the horizontal tubular  200 . Similarly, if the tubular is in a vertical position, the elevator can be moved into the latching position merely by positioning the elevator up against the tubular and pushing the two elements together i.e., the elevator against the side of the vertical tubular.  
         [0046]    [0046]FIGS. 6, 7 and  8  illustrate some additional features and alternative embodiments of the invention. FIG. 6 shows the U-shaped elevator  1  with a pipe section P in the throat  2 . Latch  3  in arm  1   a  is in the closed position to retain the pipe in the throat. Latch  4 , in arm  1   b,  is in the open position to allow pipe to move in or out of the throat. Latches  3  and  4  correspond, for the most part, to the latches  102  and  104  previously described herein, both as to structure and as to function.  
         [0047]    Ears  1   d  and  1   c  of the elevator  1  are situated such that their centerline passes some distance d toward the throat from the pipe centerline, identified as PCL in FIG.6. Point LV is the origin of a lift vector when a pipe load is lifted by a pair of bails (not illustrated) which engage the ears  1   d  and  1   c,  respectively. The ears can rotate in the loops of the bails (not shown) which suspend the elevator from the traveling block. When lifted pipe is vertical, the pipe usually has a top coupler with a downwardly facing plane surface that rests on the area  1   e  of FIG. 6. With the area interrupted by the throat gap, the geometric center of the lift area is usually near the lift vector LV. This is an optional feature and the distance d is a design choice influenced by elevator size and the nature of the expected pipe string load.  
         [0048]    [0048]FIG. 7 illustrates alternative details of latch  3 . In arm  1   a,  post  7  bearingly supports rotating members  5  and  6 . Member  5  is the blocking member that prevents movement of pipe into and out of the throat. Member  6  is the incoming load sensor lever. When engaged by incoming pipe, lever  6  pivots about post  7 , pushes link  8  to rotate member  10  about secondary post  9  to lift recess  10   a  clear of post  11 . The blocking member  5  then rotates about post  7 . Post  9  is mounted on member  5  and swings with member  5 . Posts  11  and  7  are secured within the arms  106  and  108  of the elevator  100  illustrated in FIG. 3.  
         [0049]    The access to the throat can be cleared by pulling handle  12  toward the free end of the arm. That action rotates member  10  about secondary post  9  and all elements mounted on member  5  rotate counterclockwise to pull blocking member  5  out of the throat access, to free pipe to move from the throat of the elevator.  
         [0050]    Springs  15  and  16  bias the blocking member to the closed state and bias the security lock, element  10  on post  11 , to the locked state.  
         [0051]    Hand grip  14  is used for manually moving the elevator and glove shield  13  to keep gloves out of the mechanism.  
         [0052]    Alternatively, a powered version of the latch mechanism leaves the option of manual manipulation of the latches unencumbered. A motor  20  rotates (see FIG. 3) post  7 , as an output shaft of the motor  20 . The post  7  is keyed to element  6  and bearingly situated in plates  1   a  and  1   aa  as well as blocking member  5 . Motor  20 , can be secured to plate  1   aa , and driving pinion  21 , in mesh with gear teeth  6   a  on lever  6 , as an alternate arrangement, requiring cutaway  5   a  in one side of the blocking member  5 .  
         [0053]    The mounting and configuration of driving motor  20  accommodates either fluid powered or electric drive systems. Open center valving serves motor  20 , if fluid is used, to facilitate free wheeling of the motor for manual latch operation. The motor  20  can be mounted on either plate  1   a  or plate  1   aa  to project either above or below the elevator.  
         [0054]    [0054]FIG. 8 shows plates  1   a  and  1   aa,  and only the elements involved in adaptation for motor use of the latching mechanisms described herein. Plates  1   a  and  1   aa  are continuations of the lower and upper surface plates defining the envelope of the body of the elevator which is currently of weldment construction. Current construction practices are not to be construed in a limiting sense.  
         [0055]    From the foregoing, it will be seen that this invention is one well adapted to attain all of the ends and objects hereinabove set forth, together with other advantages which are obvious and which are inherent to the elevator described and illustrated herein.  
         [0056]    It will be understood that certain features and sub-combinations are of utility and may be employed without reference to other features and sub-combinations. This is contemplated by and is within the scope of the claims.  
         [0057]    As many possible embodiments may be made of the elevator of this invention without departing from the scope thereof, it is to be understood that all matter herein set forth or shown in the accompanying drawings is to be interpreted as illustrative and not in a limiting sense.  
         [0058]    While the preferred embodiment of the present invention contemplates the use of an elevator having a U-shape with parallel arms, the arms can either be parallel, or inclined slightly towards each other or even inclined slightly away from each other. Moreover, while the present invention contemplates that a given elevator will have a single pair of latching mechanisms, the elevator according to the present invention could also include two or more pairs of latching mechanisms which could be used to entrap a tubular within the elevator.