Horseshoe shaped elevator and method for using same

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.

FIELD OF INVENTION

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

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.

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 a joint of drill pipe, the elevators are latched onto the pipe just below the tool joint (coupling) which prevents the drill pipe from slipping through the elevators. 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.

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.

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.

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.

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.

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

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.

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'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.

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.

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.

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.

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.

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.

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.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

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 elevator10has a donut shaped body12, having a center orifice14for encircling a tubular16such as is illustrated inFIG. 1(c). The elevator10has a pair of ears18and20having holes19and21, respectively, to which the bales (not illustrated) can be attached. The elevator10is quite thick, for example,8to10inches 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 elevator10has a door24which is made to rotate about a pivot pin26to open or close the door24. As illustrated, the door24is in the closed position and is latched to the remainder of the elevator10to secure it into position. When the door24is to be opened to allow a tubular within the orifice14to be released, the door24is unlatched and pivoted around the pivot pin26as shown by the rotational arrow28.

FIGS. 1(b) and1(c), respectively, illustrate a top plan view of a tubular16to be entrapped within the elevator10and an elevated, partial view of the tubular16. The tubular16has an upset, enlarged end portion30having an outside diameter32as measured between the two lines34and36. The tubular16also has a primary section40below the upset portion30which has a reduced diameter as measured between the two lines42and44. The portion40of the tubular is sized to fit within the interior orifice14of the elevator10as illustrated inFIG. 1(a). Whenever the door24is opened, the elevator10fits around the tubular16at a point along the tapered surface50of the tubular16. As is well known in the art, the tubular16also includes a passage52along its length for allowing drilling fluid or other fluids to pass therethrough when the tubular is in an earth borehole (not illustrated).

In the operation of using the prior art elevator illustrated inFIG. 1, when it is desired to have the elevator10latch onto the tubular16, whether from the horizontal or vertical positions, the door24has to be opened to allow the remainder of the elevator10to latch onto the tubular16at a point just beneath the upset portion30. It should be appreciated that when the tubular is very heavy, for example 20″ to 30″ heavy steel casing, the elevator10is quite large, weighing several hundred pounds, and it requires a great amount of human effort and exposure to safety hazards to open the door24and engage the tubular16with the elevator10.

It should be appreciated that althoughFIG. 1(a) illustrates a prior art elevator having a single door which pivots around a pivot pin26, the prior art also includes a pair of doors (not illustrated) which together accomplish somewhat the same function as the door24, 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.

Referring now toFIG. 2, there is illustrated another type of prior art elevator60which 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 elevator60. This type of elevator60is 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. Elevator60has a pair of attachment rods64and66around 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 ofFIG. 1.

The light weight tubular62ofFIG. 2has an upset end70sized to ride on the top of the elevator60while the primary portion of the tubular62below the upset end portion70is sized to fit through the side opening72of the elevator60. 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.

Referring now toFIG. 3(a), the elevator100is illustrated in this preferred mode of the invention as being essentially U-shaped, sometimes referred to as having a horseshoe shape. A first latching mechanism102and a second latch mechanism104are located, respectively, within the two arms106and108of the U-shaped elevator100. The two arms106and108, together with the arcuate end section105form the U-shape. A “stick figure” illustration of a human being110, 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 handle112. The latch mechanism104is illustrated as being in the open position, whereas the latch mechanism102is in a closed position, as will be explained in more detail with respect toFIG. 4, hereafter. Although explained in more detail with respect toFIG. 4andFIG. 5, it should be appreciated that as the pipe or other tubular enters the open end of the horseshoe shaped elevator100, the tubular will contact the latching mechanisms102and104, causing both of them to assume the open position as shown inFIG. 3for mechanism104. As the tubular proceeds further into the interior of the U-shaped elevator100the mechanisms102, and104will return to the closed position as illustrated with respect to mechanism102ofFIG. 3, thus entrapping the tubular within the interior of the elevator100.

Referring now toFIG. 4, the enlarged view of the latch102is now described in greater detail. It should be appreciated that the latches102and104are in cut-outs in the sides of arms106and108, respectively, of the elevator100, and are not located on the top surface of the elevator100. The top surface of elevator100is sized to be smaller, in its internal diameter, than the external diameter of the upset end of the casing being raised or lowered.

The latch mechanism102inFIG. 4includes a disconnector arm130having a wear pad154which will be contacted first by the tubular to be entrapped. The arm130is pivotable about a pivot rod132which, as illustrated inFIG. 3(b), traverses the width of arm106. A spring149encircles the pivot rod132, and has a first end155located against the back surface of the wear pad154, and a second end151located against the elevator handle152which is used merely to hand position the elevator100, if and when needed.

A disconnector link134has a first end connected to the disconnector arm130and a second end connected to a safety latch plate120. The plate120has a recess126sized to receive a rod124, which as illustrated inFIG. 3(b), traverses the width of arm106.

Further inFIG. 4, the plate126is illustrated as being pivotable about a rod122, which has a spring160encircling the rod122and having a first end located against one end of the disconnector link134and a second end connected within a manual handle170. The handle170is illustrated as shorter than its actual length, which may be one to two feet long for case of operation.

The tubular catch131is 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 surface133closely approximating the curvature of the entrapped tubular, for example, as illustrated in step10ofFIG. 5. The catch131also pivots around the pivot rod132, and has a width closely approximating the width of the arm106.

FIG. 3also illustrates a bale attachment member112, one of which is attached to each of the arms106and108, allowing the elevator100to be used with a traveling block (not illustrated).

In the operation of the latch mechanism102ofFIG. 4, the latch is illustrated as being in the closed position, exactly the same position as if a tubular were trapped inside the elevator100. The latch mechanism104ofFIG. 3, which is a mirror image of latch mechanism102, 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 latches102and104, (e.g., wear pad154of arm130of latch102).

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., plate120, allowing the pipe catches, e.g. catch131, 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'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.

It should be appreciated that as the tubular to be trapped within the elevator touches the disconnector arm such as arm130inFIG. 4, the disconnector link134causes the safety latch plate120to disengage from the rod124. As the tubular moves further past the catch131, the plate120swings into position such as is better illustrated for latch mechanism104inFIG. 3, which illustrates the disconnector link134as being essentially perpendicular to the longitudinal axis of the arm108. In that position, the latch104is in the open position and allows the tubular to be further inserted within the interior of the elevator100. As the tubular goes past the latch mechanisms102and104, the latch mechanisms102and104return to their closed position such as is illustrated by the latch mechanism102inFIG. 3.

W hen the tubular which is entrapped within the elevator100is in a position which no longer requires the elevator100to be used, the handle170illustrated inFIG. 4is rotated manually to return the latch mechanism102to its open position. The corresponding handle for latch mechanism104is similarly rotated, and with each of the latch mechanisms102and104in the open position, the elevator100is easily removed from the tubular.

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 ofFIG. 5in which the elevator100is lowered onto the horizontal tubular200. 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.

FIGS. 6,7and8illustrate some additional features and alternative embodiments of the invention.FIG. 6shows the U-shaped elevator1with a pipe section P in the throat2. Latch3in arm1ais in the closed position to retain the pipe in the throat. Latch4, in arm1b, is in the open position to allow pipe to move in or out of the throat. Latches3and4correspond, for the most part, to the latches102and104previously described herein, both as to structure and as to function.

Ears1dand1cof the elevator1are situated such that their centerline passes some distance d toward the throat from the pipe centerline, identified as PCL inFIG. 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 ears1dand1c, 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 area1eofFIG. 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.

FIG. 7illustrates alternative details of latch3. In arm1a, post7bearingly supports rotating members5and6. Member5is the blocking member that prevents movement of pipe into and out of the throat. Member6is the incoming load sensor lever. When engaged by incoming pipe, lever6pivots about post7, pushes link8to rotate member10about secondary post9to lift recess10aclear of post11. The blocking member5then rotates about post7. Post9is mounted on member5and swings with member5. Posts11and7are secured within the arms106and108of the elevator100illustrated inFIG. 3.

The access to the throat can be cleared by pulling handle12toward the free end of the arm. That action rotates member10about secondary post9and all elements mounted on member5rotate counterclockwise to pull blocking member5out of the throat access, to free pipe to move from the throat of the elevator.

Springs15and16bias the blocking member to the closed state and bias the security lock, element10on post11, to the locked state.

Hand grip14is used for manually moving the elevator and glove shield13to keep gloves out of the mechanism.

Alternatively, a powered version of the latch mechanism leaves the option of manual manipulation of the latches unencumbered. A motor20rotates (seeFIG. 3) post7, as an output shaft of the motor20. The post7is keyed to element6and bearingly situated in plates1aand1aaas well as blocking member5. Motor20, can be secured to plate1aa, and driving pinion21, in mesh with gear teeth6aon lever6, as an alternate arrangement, requiring cutaway5ain one side of the blocking member5.

The mounting and configuration of driving motor20accommodates either fluid powered or electric drive systems. Open center valving serves motor20, if fluid is used, to facilitate free wheeling of the motor for manual latch operation. The motor20can be mounted on either plate1aor plate1aato project either above or below the elevator.

FIG. 8shows plates1aand1aa, and only the elements involved in adaptation for motor use of the latching mechanisms described herein. Plates1aand1aaare 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.

Referring now toFIG. 9, an alternative embodiment of the present invention is illustrated in more detail. The ‘Articulated-Cradle Elevator’ (“A.C.E.”) is a tool designed to lift ‘square shouldered’ tubulars quickly and safely. Tubulars may be lifted either vertically or from the horizontal. This ability allows the A.C.E. to function efficiently in dual modes as both the main tubular string-elevator and as a single joint elevator.

In the current, preferred embodiment, the A.C.E. consists of a body200that, functions as the basic platform to which, the lifting ears202and the cradles204are affixed. The body200structure is a beam, fabricated or otherwise, resembling a rectangular hollow tube—other shapes may be appropriate depending on tool size, capacity or other economic factors—formed into a three-sided “U” shape, as illustrated inFIG. 13, leaving one side201, called the throat, open for movement of the oilfield tubular206into or out of the A.C.E. The lifting ears202are designed for a specific size bail, depending on the intended capacity of the tool. The cradles204are designed to wrap around the tubular206, under the square shoulder203, illustrated inFIG. 14, to a far more substantial degree than is possible with ‘Horseshoe’ type elevators, illustrated inFIGS. 3–8herein, whose very nature typically limits the contact to a maximum of 180 degrees. Also, the cradles204greater bearing surface of up to approximately 250 degrees is centrally located in relation to the centerline205of the lifting ears202, thus allowing the elevated tubular to hang perfectly straight. This latter feature is sometimes not possible with Horseshoe type elevators of large capacity due to their eccentric bearing surface in relation to the ears.

The ability of the cradles204to wrap around the tubular206to such a great degree is a function of their being able to pivot to open and closed positions. In the open position the cradles204swing out of the throat201of the body200so that, a tubular206may move unhindered into or out of the body200and in the closed position, the cradles204swing into the throat201of the body200and encircle the now trapped tubular206centrally over the lifting ears202. The cradles204are attached to the body200by means of pivot pins207and are urged to the normally open position by the cradle-open springs209. Whenever a tubular206enters the open A.C.E. it pushes against the back of the cradles204moving them to the closed position. When the closed position is attained, the sliding lock blocks211are freed from the open position and are urged backward to the lock position by the lock springs213. The unlocking handles215are now in the extreme back of their respective slots and this provides reliable visual indication of lock status. The tubular206is now securely trapped within the closed cradles204. To remove the tubular206, the sliding lock blocks211must be moved to the forward position either manually or by a motor. Unlocking handles215are provided for manual operation. As soon as the sliding lock blocks211are moved out of the way, the cradle-open springs209articulate the cradles204pivotally to the open position, ejecting the tubular206from the A.C.E. and trapping the sliding lock block211in the forward or open position.

The improvements are: (1) Greater shoulder bearing area via the cradles more generous wrap around and centralized location, insuring less stress on the collar of the tubular and providing greater lifting capacity; (2) Centralizing the tubular over the lifting ears for a perfectly straight lift which, aids stabbing into the previous joint; (3) Superior lock strength by means of a solid lock block rather than numerous pins and linkages, to assure the tubular remains securely within the A.C.E.; (4) Simplified operation by means of a straight pull, single motion handle; (5) Increased operator safety due to the operating handles being far removed from the lift bails to preclude pinching injuries; (6) Simple, accurate, reliable visual indication of lock status, thus eliminating the need for operator intervention to ensure lock-up.

Referring now toFIG. 10, there is illustrated another view of the embodiment of the present invention illustrated inFIG. 9. InFIG. 10, there is illustrated, essentially, what is the embodiment ofFIG. 9and its mirror image. The parts are essentially in duplicate, and numbered the same and shows essentially the same parts, in the same positions, as illustrated inFIG. 9. With the release handles215in the open position, the springs209will cause the cradles204to move to the “open position” and allow the casing or other tubular206to be moved into the position within the interior of the cradles204. By releasing the handles215, the cradles204will wrap themselves around the exterior of the casing206but underneath the square collar having shoulder203illustrated inFIG. 14. As discussed herein above, the cradles204, respectively, will pivot around the pivot pins207and the cradles can be moved into the throat201of the “U” shaped body200illustrated inFIG. 13. This is made possible by the cutaway section213of each of the cradles204to allow the cradle204to fully pivot as desired, under which the cutaway section213can slide into the throat of the body200. Once the tubular206is fully within the confines of the cradles204, whereby the cradles204can ride underneath the square shoulder surface203illustrated inFIG. 14, the cradles are locked into position and cannot be unlocked until the manual release handles215are activated, or alternatively, the manual handles215can be actuated by a motor such as a pneumatic motor or hydraulic motor to release the handles215and allow the tubular206to be removed from the body200. It should be appreciated that inFIG. 10, the lifting ears to which the bails are attached are not illustrated but they are each identical with the lifting ear202as illustrated inFIG. 9.

In operation, of the device as illustrated inFIGS. 9 and 10, after the cradles are fully in place underneath the square shoulder203illustrated inFIG. 14of the tubular206, the elevator having the body200, is raised or lowered to move the tubular206into the vertical or horizontal positions as desired. When it is desired to release the tubular206from the apparatus illustrated inFIG. 10, the release handles215are manipulated, either manually or by a motor, for example, a pneumatic or hydraulic motor or two such motors to handle the two handles215, to cause the cradles204to move completely out of the path of the tubular206to enable the tubular to be fully released from the elevator illustrated inFIG. 10.

Referring now toFIG. 11there is illustrated yet another alternative embodiment of the present invention. The Horseshoe body300is comprised of two lift ears302and one not shown and two bearing surfaces, the bearing304and one not shown. Affixed to the body300are the lift pins, one lift pin306and one not shown, and two flaps, the flap308and one not shown. The Flap308is rotated on the hinge pin310out of body opening312to allow the tubular314to enter into body300. This may be accomplished manually or by lowering the body300over the tubular314. Once the tubular314is fully inserted into body300, flap308automatically, by spring force or by motor means, is returned to the closed position as shown inFIG. 11, trapping the tubular314within the body300. Upon lifting the Horseshoe elevator300, the collar of the tubular314rests evenly on top of flap308and on bearing surface304, as well as on their mirror image counterparts.

With this system the lift pin306is located on the center of the tubular314so that the weight of the tubular314is carried symmetrically on the axis of the tubular314and the tubular314hangs straight.

It should be appreciated that in using the apparatus illustrated inFIG. 11, the Horseshoe Elevator300illustrated inFIG. 11, has a mirror image on its other side such that there are two of everything illustrated inFIG. 11. Thus, there are two sets of wear surfaces304, two sets of Flaps308, etc., which all work together. In the use of the elevator illustrated inFIG. 11, the flap308is rotated out of the way by causing it to pivot around the pivot pin310until the tubular string314can be moved into the opening within the Horshoe Elevator300. After the tubular314is in place within the elevator, the flap308on each side is rotated to be around the tubular314and the elevator300can be manipulated in the usual ways to either raise, lower or otherwise manipulate the tubular314. It should be appreciated, in using the elevator illustrated inFIG. 11, that to capture the tubular within the elevator300, the flap308is rotated to ride under the square collar203of the tubular206(or the tubular314, as the case may be). This causes the wear pad304and the flap308to both be under the square collar on each side of the elevator illustrated inFIG. 11. In use, it should be appreciated that the two sets of flaps308and the two sets of wear pads304are each under the square collar of the tubular314which allows the tubular314to be raised, lowered or otherwise manipulated because all of the weight of the tubular will be born by the two sets of wear pads304and the two flaps308.

Referring now toFIG. 12, there is illustrated a single door elevator400which has a body402and the single door404which pivots around a point on the line406. Before the door404is rotated to open up the elevator400, it is secured to the body400by any conventional latching mechanism408as desired.

As seen further inFIGS. 12aand12b, the door404is rotated through the use of a fluid driven activator410which can be used to rotate the door404to the open position or to rotate it in the reverse direction to close the door404against the body402to allow the latching mechanism408to hold the body402and the door404in the secured position. The fluid driven actuator410is powered by a pump412which can be either pneumatic or hydraulic and supplies the fluid under pressure through the flexible line414to the actuator device410.

As illustrated inFIG. 12b, the dotted line416illustrates the path through which an oilfield tubular can be moved without being forced into contact with any point of the elevator. This leaves an unimpeded path for the tubular such as the tubular206ofFIG. 14. This feature is accomplished, by always having the point418of the door to the left hand side of the dotted line416as viewed inFIG. 12b. It should be appreciated that if the point418is to the right side of the dotted line416, the tubular moving into or out of the elevator may very well bump the point418of the door and impede the travel either into or out of the elevator illustrated inFIGS. 12aand12b.

Referring now toFIGS. 15aand15b, there is illustrated a two-door elevator500having a body502and first and second doors504and505which can be maintained in the closed position by a latching mechanism508. The door504is open and/or closed by the actuator510which is controlled by a fluid pump512connected between the pump512and the actuator501. In a similar vein, the door505is opened or closed by the actuator511controlled by a fluid pump513through a flexible line515.

It should be appreciated that the pumps512and513can be individual pumps or can be the same pump to drive the actuators510and511, and can be either pneumatic or hydraulic as desired.

FIG. 15balso illustrates a pair of dotted lines which are parallel to each other and which define the area into which the doors504and505, respectively, are rotated to make sure that the respective points520and522are clear of the tubular as such tubular leaves or enters the elevator500. Thus, when the door504is rotated to cause its point520to be on or to the left side of the line516and the door505is rotated to cause the point522to be on or to the right side of the dotted line518, the tubular to be moved into or outside the elevator will always have an unobstructed path. This characteristic is advantageous in that it will prevent the doors504and505from being damaged by the heavy weight oilfield casing as it is moved into or outside of the elevator500, which also prevents damage to the tubular. This is, of course, the very same reason for maintaining the point418of the door404inFIG. 12bon or to the left side of the dotted line416.

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.

While one or more of the preferred embodiments 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.