IMPROVED OILFIELD TUBULAR ELEVATOR AND METHOD FOR USING SAME

Abstract: A U-shaped elevator (100) having no doors is provided with first and second latching mechanisms (102, 104) which when contacted by the tubular to be entrapped within the elevator (100) 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 (100). The latching mechanisms (102, 104) have a safety catch (120) which prevents the tubular from being inadvertently removed from the elevator (100). The release of the safety latch mechanism (120) can only be activated by a handle (170) which is manipulated by hand by personnel working on the derrick utilizing the elevator (100).

Description: IMPROVED OILFIELD TUBULAR ELEVATOR AND METHOD FOR USING SAME FIELD OF INVENTION The invention relates, generally, to elevators used for lifting and lowering oilfield tubulars out of, or into an oil, gas or geothermal 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. 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 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. 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. 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 always been constructed with doors (generally, one or two) which open to allow the sideways 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 lower side of the tubular, the tubular end around which the elevator is placed must be above the derrick floor. 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. These and other objects, features and advantages of the present invention will be better understood and appreciated from a reading and review of the detailed specification and accompanying drawings set out herein. BRIEF DESCRIPTION OF DRAWINGS 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: Fig. 1 is a diagrammatic view of a prior art, oilfield tubular elevator; Fig. 2 is a diagrammatic view of a second prior art, oilfield tubular elevator; Fig. 3 is a top plan view of the elevator according to the present invention;. Fig. 4 is an expanded view of a latch mechanism used with the elevator illustrated in Fig. 3 according to the present invention; and 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. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings in more detail, Fig.l(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. 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 dotted 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 dotted 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). 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. 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. 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. 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. 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 1 10, 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 1 12. 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 opening end of the horseshoe shaped elevator 100, the tubular will contact the latching mechanisms 102 and 104 causing 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. 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 latch mechanism 102 includes a disconnector arm 130 having an elastomeric 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 150 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. 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. 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. 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 12 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. Fig. 3 also illustrates a bale attachment member 113, 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). In the operation of the latch mechanism 102, 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, 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 disconnector arms of the two latches 102 and 104 (arm 130 of latch 102). 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'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 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(a). W hen 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. 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. 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.

Claims: CLAIMS What is claimed is: 1. An improved elevator for lifting and lowering oilfield tubulars, comprising: a) a U-shaped elevator body having an end portion and first and second arms extending from said end portion, said first and second arms being separated by a distance larger than the primary outside diameter of the tubular to be lifted and/or lowered; b) a first latching mechanism carried by said first arm; c) a second latching mechanism carried by said second arm, each of said latching mechanisms having an open position and a closed position, and each of said latching mechanisms being structured such that said latching mechanisms move to an open position responsive to contact by a tubular and return to a closed position responsive to said tubular being positioned within said elevator body. 2. The elevator according to Claim 1 , wherein said first and second arms are parallel. 3. The elevator according to Claim 1, including in additional thereto, first and second bail attachment members connected to said first and second arms, respectively. 4. The elevator according to Claim 1 , wherein said first and second latching members are structured such that a tubular can be released from the elevator only in response to the manipulation of manually operated first and second override handles, respectively. 5. An improved elevator for lifting and lowering oilfield tubulars, comprising: a) a U-shaped elevator body having an end portion and first and second arms extending from said end portion, said first and second arms being separated by a distance larger than the primary outside diameter of the tubular to be lifted and/or lowered; b) a first latching mechanism carried by said first arm; c) a second latching mechanism carried by said second arm, each of said latching mechanisms having an open position and a closed position, and each of said latching mechanisms being structured such that said latching mechanisms move to an open position responsive to contact by a tubular and return to a closed position responsive to said tubular no longer being in contact with said latching mechanisms. 6. A method for entrapping an oilfield tubular within an elevator, comprising the steps of: positioning said elevator above an oilfield tubular; and lowering said elevator over said tubular to thereby entrap said tubular within said elevator. 7. The method according to Claim 6, including the additional step of lifting said elevator with said tubular entrapped therein. 8. The method according to Claim 6, wherein said tubular is positioned other than vertically prior to said elevator being lowered over said tubular. 9. The method according to Claim 8, wherein said tubular is positioned horizontally prior to said elevator being lowered over said tubular. 10. A method for entrapping an oilfield tubular within an elevator, comprising the steps of: positioning an elevator beside an oilfield tubular; and entrapping said tubular within said elevator by pushing the elevator and the tubular into latching engagement with each other. 11. The method according to Claim 10, wherein the tubular is vertical prior to the elevator and the tubular being pushed into latching engagement.

Inventors: MOSING DONALD E, SIPOS DAVID L, MOSING, DONALD, E., SIPOS, DAVID, L.
Applicants: FRANK S INR INC, MOSING DONALD E, SIPOS DAVID L, FRANK'S INTERNATIONAL, INC., MOSING, DONALD, E., SIPOS, DAVID, L.
Application year: 2000
Main classification: E21B19
IPC codes: E21B19