CA1156214A - Bowl and slips assembly with improved slip inserts - Google Patents

Abstract

BOWL AND SLIPS ASSEMBLY WITH IMPROVED SLIP INSERTS
Abstract A bowl and slips assembly for supporting tubing in a well includes a plurality of gripping inserts supported on slip bodies by means of a cantilever connection with the in-serts hang-supported from the top surfaces of the bodies so the bodies are in compression when supporting tubing in the well. In comparing adjacent slip bodies, one includes a shoulder formed in the top surface thereof so adjacent in-serts are supported in vertically spaced positions. A safety ledge integrally formed with each body prevents broken inserts from falling into the well.

Description

This is a division of commonly assigned Canadian Patent Appli,cation Sexial No. 374,317 ~iled Maxch 3i, 1981.
- Technica} Field This invention relates generally to a bowl and slips assembly such as may be used in supporting tubing in a well snd, more'specifically, relates to the construction o~ the assembly in providing for the use of removable slip inserts.
Background Art In the petroleum industry, a bowl and slips assembly, typically referred to as a spider and slips, comprises a sup-10 port or bowl having a central opening through which tubing ~, may extend downwardly into an oil well. The sides of the opening are tapered inwardly upon progressing downwardly through the bowl so the opening is generally of an inverted frustoconical shape. To support the tubing upwardly within 15 the bowl, a series of bodies in the form of frustoconicalsegments are telescoped into the opening, In one form of assembly, there are four such slip bodies dividing the open-ing into quadrants. Together, the slip bodies define a cylindrical passage through the central opening and the pas-20 sage is particularly sized to receive the tubing for supportby the assembly. Carried on the inside sur$aces of the slip bodies for gripping against the outside of the tubing are removable inserts having vertically spaced teeth which typically are configured for one-way grippin~ to keep tubing 2S from sliding downwardly in the well.
In service use, pairs of the slip bodies may be sup-ported in retracted positions spaced outwardly from opposite sides of the opening to allow tubing to be lowered into the well. When it is,desired to move the slip bodies and inserts " 11562~4

-2-into the opening to grip the tubing, the bodies are moved into set positions with the teeth gripping a~ainst the tu~ing.
Sometimes gripping occurs before downw~rd movement of tubing being lowered into the well is halted and, as a result, high instantaneous forces are generated in the assembly~ It will be appreciated that these forces of dynamic loading applied to the inserts and slip bodies can be quite high, particularly when the assembly is used to support the weight of thousands of feet of tubing.
10 Disclosure of Invention ... ..
In general, the present invention contemplates a bowl and slips assembly of the foregoing general character which is easier to use and which has a longer service life than prior similar bowl and slips assembliesO In this re-15 spect, the present invention provides connections between theslip bodies and their inserts which are constructed in a particularly unique fashion so that wear and metal fatigue associated with repeated loading in tension during in service use is concentrated in the easily replaceable inserts rather ! 20 than in other parts of the assembly such as the slip bodies.
Primarily, the present invention resides in the con-struction of the bowl and slips assembly to include a novel cantilever connection for hanging each of the inserts from their respective slip bodies so the reaction forces throug~
25 the assembly when supporting the tubing places the slip bo~ies in compression. Specifically, the inserts arè hang-suppor~ed from top surfaces of the slip bodies and, between adjacent pairs of slip bodies, these top surfaces are spaced vertically from each other to advantageously position horizontally 30 parallel gripping teeth of identical inserts in vertically offset patterns to avoid creating an unbxo~en line of force concentration completely around the tu~ing supported by the assembly.
The invention also resides in the novel manner of 35 mounting the inserts in the slip bodies for easy removal ana replacement and in the provision of a safety ledge for keeping the inserts from dropping into the well in the event the cantilever connection should fail The invention accordiny to the ~arent applica~on may be considered as providing a bowl and sl~ps asse~ly ~or support-inq tubing upwardly within a well, comprisin~: a support ~owl with a downwardly tapered opening therethrough for the tubing to extend into the well, a first pair of sli~p ~odies pivotally mounted on the bo~1 adjacent one side of the openîng for movement between a retracted position spaced clear of ~he.
opening and a set position within the. opening, a second similar pair of slip bodies pivotally mounted on thed support bowl on the opposite side of the opening for similar movement between retracted and set positions relative to thël opening, fluid pressure actuating mechanism mounted on the.. support bowl and connected ~etween thed first and second pairs of slip bodies for moving thë.. pairfi of slip bodies simultaneously between their retracted and set positions, each of the.. slip bodie~s having an insert connected thereto and carried thereby for gripping against the outside surface of the tubing to support the latter upwardly in the well, and a cantilever connection between the inserts and their associated slip bodies, the;l connections supportively hanging each of the.. inserts in a loaa bearîng position from their respective slip bodies so the weight of the tubing supported by the assembly piaces the;l slip bodies in compression.

Statement of Invent;.on On the other hand the invention according to this divisional application may be considered as providing a bowl and slips assembly having a plurality of tapered slip bodies with associated gripping inserts angularly spaced about the central axis of and mounted on a support bowl for movement between retracted and set positions with respect to a tapered opening in the bowl for the inserts to grip against the outside surface of tubing to support the latter upwardly in a well, the improvement in the assembly comprising a cantilever connection hang support-ing`each of the inserts from their respective slip bodies`
in a load bearing position so the reaction of forces through the assembly when supporting tubing places thé slip bodies in compression, each of the connections including a top surface on the 51ip bodies and each of the inserts includ-ing an inner gripping surface and a lip projecting outwardly therefrom with the lips being in overlapping abutting engage-ment with the top surfaces of the slip bodies in the load bearing position, and with the inserts being substantially identical to each othar and the inner gripping surfaces thereof ~eing compri~ed of a plurality of vertiaally spaced, substantially parallel teeth, and the top surfaae of one slip body being offset vertiaally from the top surface of an adja, cent slip body.

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These and other objects and adv~ntages of the present invention will become more apparent from the follow-ing description when ~aken in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF DR~WINGS
Fig. l is a front view of a bowl and slips assembly embodying the novel features of the present invention.
Fig. 2 i5 a back view of the bowl and slips assembly of Fig. 1.
Fig. 3 is a plan view of the assembly shown in Fig. 1.
Fig. 4, on the same sheet as Fig. 1, is a view similar to Fig. 2 but showing parts of the assembly in moved positions.
Fig. S is a perspective view showing specific parts of the assembly in exploded relationship to each other with other parts of the assembly-omitted for clarity.
Fig. 6 is a partial, cross-sectional and elevational view taken substantially along line 6-6 of Fig. 3.
Fig. 7 is an enlarged, fragmentary view taken sub-stantially along line 7-7 of Fig. 3.
~igs. 8 and 9 are enlarged perspective views of different sides of a slip body insert utilized in the exem-plary bowl and slips assembly.
BEST MODE OF CARRYING OUT THE INVENTION
As shown in the drawings for purposes of illustration, the present invention is embodied in a bowl and slips assembly 15 such as is used in the petroleum industry to support tubing (not shown) in an oil or gas well. Herein, the assembly comprises the support bowl 16 with a bottom flan~e 17 . 1156214 ~see Figs. 1 and 6) for attachincJ the bow] at the well.
head. When removed, a gate 19 in one side of the bowl connects tubing to be loaded sideways into axial alignment with the well bore. In place, the inner surface of the gate is tapered in conformity with the remaining portion of the bowl to define a central opening 20 through which the tubing may be lowered into the well. The gate is held against radial movement relative to a central axis 21 of the opening by interfitting groove 23 and ridge 24 connections formed in opposite ends of the gate (see Fig. 3) and the adjacent sides .

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of a gate opening 25 in the bowl. Additionally~ a retaining pin 26 telescoped horizontally through the bowl and the gate serves to support the gate against vertical movement once in place.
The central opening 20 of the bowl 16 is generally - of an inverted, frustoconical shape and thus tapers inwardly upon progressing downwardly through the bowl. To support the tubing within the bowl, a series of similarly tapered slip bodies 27a and 27b and 28a and 28b fit within the opening and 10 include inner gripping surfaces or teeth 29 particularly adapted to bite agaînst the outside of the tubing within the bowl and support such tu~ing against downward movement into the well. -Herein, teeth 29 are formed on the inside surface of removable inserts 30 carried by the slip bodies and are 15 shaped for one-way gripping to keep the tubing from sliding downwaraly in the well. Because of the ~edge effect of the slip bodies in the tapered opening, downward move~ent of the tubing produces an almost instantaneous gripping of the tubing ~ by the teeth 29.
;~ 20 More particularly, as shown in ~ig. 3, the slip bodies are connected in pairs 27a, 27b and 28a, 28b on carrier arms 31 and 33, respectively, which are disposed on opposite sides of the bowl 16 for movement between set positions with the slips disposea within the opening 20 and retracted posi-25 tîons with the slips pivoted upwardly and outwardly of the opening as shown specifically in Fig. 4. ~erein, a hydraulic actuating mechanism 34-is utilized to pivot the carrier arms 31 and 33 in lifting the slip bodies from their set positio~s and into their retracted positions. As shown in Figs. 3 and 30 6, such mechanism includes a hydraulic cylinder 35 supported on one side o the bowl 16 with a rod end 36 of the c~linder facing upwardly. A rod 37 connected to a piston 3~ ~Fig. 6~
in the cylinder projects upwardly therefrom to connect pivo -ally with the carrier arm 31 intermediate inner and outer erds 35 40 and 41 thereof. The outer end of the carrier arm 31 is fixed to a pivot sha~t 43 rotata~ly supported within journals 44 and 45 (see Fig. 3) connected to the bowl. Adjacent the backside of the bowl, a lever arm 46 is fixed by one end to the shaft 43 and an opposite end o the lever arm is pivota~ly 40 connected to one end of an elongated link 47 extending alons ~156214 the back side of the bowl. At an opposite end of the link 47, a second lever arm 49 is fixed to a second pivot shaft 50 which is mounted on the bowl to connect with the arm 33 in a fashion similar to that of the shaft 43 and carrier arm 31.
5 With this construction, when hydraulic fluid through a line 51 enters the bottom of the cylinder 35~ the piston 39 is forced upwardly exhausting fluid above the cylinder to a line 53 and pivoting the carrier arm 31 and shaft 43 in a counter-: clockwise direction as viewed in Fig. 6 while at the same 10 time shifting the link 47 to the left thereby pivoting theshaft S0 clockwise and lifting both pairs of 51ip bodies 27 and 28 from the bowl simultaneously. Movement-of the slip bodies from their retracted positions into their set positions is accomplished merely by reversing the application of pres-lS sure fluid so as to flow into the cylinder through the line 53and out through line 51.
; In moving the pairs of slip bodies 27 and 28 between their set and retracted positions, interference with the tub-ing disposed in the well is avoided by virtue of a lost motion 20 connection 52 between the carrier arms 31 and 33 and the slip bodies. One such connection 52 is shown in Fig. 6 and includes a slightly elongated slot 54 formed in the inner end 40 of - -the carrier arm 31 to receive a pin 55 which connects with upright brackets or ears 56 (see also Figs. 3 and 5) extending 25 from the slip bodies 27a and 27b. A like construction mounts the slip bodies 28a and 28b on the carrier arm 33. Advanta-geously, this construction allows the slip bodies to remain in a more nearly vertical orientation relative to the central axis 21 o the opening 20 (rather than cocking angularly with 30 respect to vertical) as the carrier arms 31 and 33 are pivoted by allowing the pins 55 to traverse horizontally along the slots 54. Thus, interference between bottom inner edges 57 ~see Figs. 5 and 6) of the slip bodies 27 and 28 and the outer surface of the tubing is avoided. -In service use, it is not unusual for the slip bodies 27 and 28 to ~e moved into their set positions for supporting tubîng even though downward movement of the tubing in the well has not been halted completely. Accordingly, it will be appreciated that high instantaneous forces are .. . . ..

` 1156214 genexated in the assembly lS resulting both from the dead weight of the tubing and its dynamic loading as tb~ wei~ht impacts on the assembly when the slips bite against and are wedged in the bowl 16. As a result, substantial wear and 5 even breakage of parts of the assembly may occur from re-peated impact, loading and relative sliding of the tubing on parts of the assembly.
'- In accordance with the primary aim of the present invention, the bowl and slips assembly 15 is constructed in a 10 novel fashion for easier in service use and'''longer useful service life through the provision of a unique connection 5 between each of the 51ip bodies 27 and 28 and their associated inserts 30. Particularly, *hese connections are such that wear and metal fatigue associated with repeated loading is ~` 15 concentrated in the inserts and yet allows for easy removal and replacement of the inserts. For these purposes, the con-nections are cantilevered for hanging the inserts from their ~' respective slip bodies so the reaction of forces through the '~"'i assembly'when supporting tubing places the slip bodies in com-~- 20 pression. By virtue of constructing the assembly to utilize cantilever connections in this fashion, the useful service life of each of the slip bodies is incxeased substantially.
' Moreover, the cantilever connections are particularly suited for easy replacement of inserts as may be necessary from time 25 to time.
As shown in Figs. 6 and 7, the connections 59 uti-lized herein are substantially the same for each of the in-serts 30 and their associated slip bodies 27 and 28. Accord-' ingly, only one of the connections will be described in detail, 30 it being understood that such description applies equally tothe connections for all of the inserts and their associated slip bodies. In the present instance, the connection 59 is of a cantilever type and includes a-lip 60 formed integrally with ' the insert 3Q (see Figs. 8 and 9) and projecting outwardly 35 therefrom to overlap a top surface 61 of an associated slip body 27a. Specifically, the insert is formed substantially as a lon~itudinal quarter segment of a tubular member and includes an arcuate inner surface 63 upon which the teeth 29 axe ormed and w~ose central axis extends colinearly with the central axis 21 o the opening 2a when the insert and its associated slip body are located in their set positions.
Opposite sides 64 and 65 (see Fig. 31 of the insert extend in a generally radial direction outwardly from the inner surface 63 to intersect at generally right angles with symmetrical longitudinal flats 66 ~see Fig. 9) which define laterally spaced portions of the back side of the insert. Extending between these two ~lats is a planar outer surface 67. Pref-erably, the lip is formed integrally with the upper end of 10 the planar outer surface 67 and includes a downwardly facing lower lip surface 69 (see Figs. 8 and 9) extending outwardly in a generally perpendicular direction from the outer surface 67. Opposite end walls 70 of the lip intersect at substan-tially right angles with respect to the 1ats 66 and an out-15 ward wall 71 (see Fig. 9) extends in a generally tangentialdirection relative to the inner surface between the two end walls 70. An upper side 73 of the lip is coplanar with the top surface of the insert and thus is identified by the same reference number. ~ormed through the upper side of the lip 20 and the top surface of the insert îs a generally rectangular groove 74 extending in a generally radial direction relative to the central axis of the insert~ The insert 30 is hang-supported on the slip body 27a with the lower surface 6~ of the lip 60 overlapping and abutting the top surface 61 of the 25 body. Supporting the insert against upward movement on the body is a keeper 7S (see ~ig. 3) which in the present instance is in the form of a cotter pin extending from within the groove 74 and through the hole 76 (see Fig. 5) in an upright lug 77 which is integral}y formed with the top surface 61.
Additionally, the insert 30 is captivated on the slip body 27a by a telescoping interfit within slot means formed within the slip body. Herein, the slot means is of a configuration corresponding to the configuration of the in-sert so as to define a generally dovetail like interfit limit-35 ing the insert against movement both in a generally inward radial direction and in a sideways or circumferential direction relative to the slip body. Specifically, the slot means com-prises a recess 79 (s~e ~ig. 5) which is formed within an inner surface 80 of the slip body 27a and is defined by an `` ll5S214 ~ 8-open top, a closed side 81, and an open side. The closed side extends edgewise in a generally xadial direction for abutting engagement with the radial side 65 of the insert.
To captivate the other side of the inserk within the recess, 5 an integral projection 83 Ssee Fi~s. 5 and 81 extends up-wardly from the top surface 61 of the slip body adjacent the open side thereof and abuts the e~d wall 70 of the lip 60 with an upright sidewall 82 (see ~ig. 3) to prevent the insert from moving radially inward when the lip is seated against the top 10 surface of the slip body. The projection also serves to limit sideways movement of the insert in a direction circumferential-ly toward the open side of the recess 79. Additionally, such sideways movement is prevented by an adjacent insert 30 in the adjacent slip body 27b. Herein, the latter bod~ ~7b is a 15 mirrow image of the slip body 27a so the open sides of the recesses 79 face each other and thus sides 64 and 65 of adja-- cent inserts are juxtaposed relative to each other.
As a safety feature for supporting the insert 30 - against dropping into the well in the event of breakage during 20 in service use, an added feature of the present invention ; resides in the provision of a stop 84 for blocking downward movement of the insert in the recess 79. Herein, the stop is in the form of a ledge 84 extending radially inward from the back side of the recess. Preferably, the ledge is spaced 25 ~elo~ the top surface 61 of the slip body 27a a distance greater than the length of the insert extending beneath the lower surface 69 of the lip 60. ~s a result, when the insert 30 is positioned within the recess of the slip body 27a, the lower end 88 (see Figs. 7 and 9) of the insert is spaced up-30 wardly of the ledge 84.
Of further advantage herein, the inserts 30 are con-templated as being of identical construction with their teeth 29 extending horizontally and parallel to each other. Thus in addition to manufacturing simplicity, for example, in any set 35 of four inserts 30, the positions of the inserts in the slip bodies 27 and 28 are fully interchangeable.
To avoid creating lines of stress concentration around tubing from the teeth 29 of identical inserts 30 biting into the sides of the tubing, the present invention further _g comtemplates vertically offsetting the horizontal pattern of teeth in adjacent inserts to grip the tubing at vertically spaced positions~ For this purpose, one of the slip bodies 27a, 28a in each pair includes an upper shoulder 85 formed in the top surface 61 of the body to a vertical height e~ual to one-half the distance between two adjacent teeth 29 of the insert. Herein, the shoulder 85 is formed integrally with the top of the slip body and along the inner surface 80 there-of or supportive engagement with the lower surface 69 of the 10 insert 30. Accordingly, when all of the inserts are mounted on their respective slip bodies so the teeth 29 of adjacent inserts define a central passage 86 (see ~ig 3) through which the tubing extends into the well, the teeth are positioned bite in and support the tubing in such a way as to keep from 15 creating a continuous line of stress concentration around the tubing~ ` -- ~ To keep the slip bodies 27 and 28 from wedging too tightly together when in their set positions without tubing in the passage 86, facing side ends 87 and 89 of the slip ! . 20 bodies 27a and 28a opposite the gate 19 (see Fig. 3) include spacers 90~ Specifically herein, two of the spacèrs 90 are formed integrally on the side end wall 87 and are positioned vertically thereon for abutting engagement with two spacers on the side end wall 89 of the adjacent slip body 28a when the 25 bodies 27a and 28a are lowered in the bowl 16. With tubing extending through the bowl, however, the thickness of the spacers on the adjacent bodies 27a and 28a is such that the spacers are held apart by engagement of the teeth 29 with the tubing.
In view of the foregoing, it will be appreciated that the present invention brings to the art a novel bowl and slips assembly 15 which by virtue of the unique interfitting relationship of the slip bodies 27 and 28 and their associated inserts 30 and the novel manner of hang-supporting the inserts 35 on the slip bodies serves to increase the useful service life of the slip bodies and to allow easy replacement of the in-serts either for reasons of:wear or to accommodate tubing of different sizes. Advantageously, the cantilevered hanging support of the inserts on the slip bodies 27 and 28 is such ~lo--as to concentrate wear and metal fati~ue in the easily re-placeable inserts while subjecting the slip bodies primarily to the less harsh compressive forces of loading as compared to tensile loading forces. Replacement of the inYerts may be accomplished by simply and ~uickly a~tuating t~e hydraulic mechanism 34 to retract the slips, removing the cotter pins 75, and sliding the inserts to be removed out of the slip bodies. Thereafter, the replacement inserts may be slid into the open recesses 79 and the cotter pins 75 replaced to com-10 plete locking the inserts on the slip bodies. Reverse actua-tion of the hydraulic mechanism 34 then positions the slip bodies and inserts in the bowl 16 for gripping and supporting tubing vertically within the well.

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Claims (8)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED AS DEFINED AS FOLLOWS:

1. In a bowl and slips assembly having a plurality of tapered slip bodies with associated gripping inserts angularly spaced about the central axis of and mounted on a support bowl for movement between retracted and set positions with respect to a tapered opening in the bowl for the inserts to grip against the outside surface of tubing to support the latter upwardly in a well, the improvement in said assembly comprising a cantilever connection hang supporting each of said inserts from their respective slip bodies in a load bearing position so the reaction of forces through the assembly when supporting tubing places said slip bodies in compression, each of said connections including a top sur-face on said slip bodies and each of said inserts including an inner gripping surface and a lip projecting outwardly therefrom with said lips in overlapping abutting engagement with said top surfaces of said slip bodies in said load bearing position, and with said inserts being substantially identical to each other and said inner gripping surfaces thereof being comprised of a plurality of vertically spaced, substantially parallel teeth, and said top surface of one slip body being offset vertically from said top surface of an adjacent slip body.

2. A bowl and slips assembly as defined in claim 1 with one of said connections between said slip bodies and its associated insert being offset vertically from an adjacent one of said connections.

3. A bowl and slips assembly as defined in claim 1 with said teeth of said inserts being in an identical pattern from one insert to the next, said pattern of said teeth in adjacent inserts being offset vertically from each other.

4. In a bowl and slips assembly having a plurality of tapered slip bodies with associated gripping inserts angularly spaced about the central axis of and mounted on a support bowl for movement between retracted and set positions with respect to a tapered opening in the bowl for the inserts to grip against the outside surface of tubing to support the latter upwardly in a well, the improvement in said assembly comprising a cantilever connection hang supporting each of said inserts from their respective slip bodies in a load bearing position so the reaction of forces through the assembly when supporting tubing places said slip bodies in compression, each of said connections including a top surface on said slip bodies and said inserts being substantially identical to each other, each including an inner gripping surface comprised of a plurality of vertically spaced, sub-stantially parallel teeth, and a lip projecting outwardly therefrom with said lips being in overlapping abutting engage-with said top surfaces of said slip bodies in said load bearing position, said top surface of one slip body being offset vertically from said top surface of an adjacent slip body, and each of said bodies including an inner surface curved about a central axis thereof and dovetail slot means formed in said inner surface for receiving and captivating said inserts therein against separation from said body in at least an initial radial direction relative to said central axis, said dovetail slot means including a projection protruding from the top surface of each of said bodies, each said projection having an upright sidewall extending in a generally axial direction relative to said central axis, said lips on each insert having an end wall juxtaposed relative to one of said upright sidewalls to block said in-sert from being moved out of said slot in a generally radial direction relative to said central axis.

5. A bowl and slips assembly as defined in claim 4 with said dovetail slot means having an open top, an open side, and closed side in adjacent pairs of said insert bodies, said open sides facing each other.

6. A bowl and slips assembly as defined by claim 5 in-cluding a spacer positioned between two adjacent slip bodies of different pairs of slip bodies to keep said bodies from sliding downwardly within said tapered opening of said bowl beyond said set position when tubing is not in said bowl.

7. A bowl and slips assembly as defined in claim 4 including a safety stop on each one of said slip bodies and normally spaced directly beneath the associated insert of said body to keep said insert from dropping out of said slip body in the event said connection should fail.

8. A bowl and slips assembly as defined in claim 7 wherein said safety stop comprises a ledge integrally formed with said body and projecting radially inward therefrom to define a closed bottom of said dovetail slot means.