US2605844A - Casing centralizer - Google Patents

Description

Aug. 5, 1952 C JR.

. CASING CENTRALIZER Filed Oct. so. 1950 r llla ll :Illllli...

IN VEN TOR.

= EARN/557E LZAQK IQ,

ArraelvEx fi' I Patented Aug. 5. 1 952 UNITED STATES "P E T oF -Ical-f CASING GENTRALIZER Earnest H. Clark, Jr., Huntington Park, Califl,

assignor to Baker Oil Tools, Inc Vernon, Califi, a corporation of California Applicationctober so, 1950, Serial No. 192,981 g 12 Claims.

l I The present invention relates to devicesfor centering casing, liner, tubing and similar conduit strings in well bores.

An object of the invention is to provide improved -casing centralizers embodying bowed springs that are pulled and not pushed through restrictions in the well bore, forboth longitudinal directions of movement of the centralizers through the well bore.

Another object of the invention is to providecasing centralizers that are easily mounted on a casing string.

- A further object of the invention is to facilitate rotation of a casing string within a centralizer mounted thereon by precluding the bowed springs of the centralizer from binding on the casing, or

parts secured to the casing. v

Yet another object of the invention is to provide a casing centralizer embodying bowed springs that are prevented from bending around sharp corners or edges, such as provided'by the stop device on the casing that engages and moves the centralizer through thewell bore. Accordingly, breaking or permanent deformation of the springs is avoided.

Yet a further object of the invention is to provide a casing centralizer that coacts, with a casing coupling or stop ring in being moved through the well bore, and in which the coupling or ring does not, interfere with the inward collapsing of the centralizer springs to their fullest extent,

thereby enabling the minimum effective collapsed diameter of the centralizer to beless than if an interfering coupling or ring were present. v I This invention possesses many other advantages, and has other objects which may be made more clearly apparent from a consideration of Fig. 2 is a longitudinal sectional and elevational view of the centering device mounted on a casing string which is moving downwardly through a well bore;

Fig. 3 is a view similar to Fig. 2, in which the (o1. 166-4) casing string is moving upwardly in the well bore;

Fig. 4 is a cross-section taken along the-line 44onFig.1; I 5 Fig. 5 is a cross-section taken along the-line 5-5onFig.l. I I

As disclosed in the drawings,.-the casing centering' device includes longitudinally'space'd upper and'lower collars H], H to which jcircumferentiallyspaced outwardly'lbowed springs l2 are attached .The collars maybe provided; with notches l3 in their confronting ends, into'which the ends of the bowed springs 12 are received,- in such manner that the outer surfaces of the end portions of the springs do not extend beyondthe peripheries of the collars [0, H. The springsare suitably fastened to the collars, as by use of Welding'material' I4.

The upper collar I0 is mounted upon. and encompasses 'agenerally cylindrical stop sleeve l5 to which it.issecured, as bythe provision of circumferentially'spaced spot welds 16. This sleeve extends downwardly through the lower collar II a slight distance below the lower end of this collar, the latter being slidable along the exterior of the sleeve;v .The stop sleeve 15 itself, mayjbe made of relatively thin sheet'metal; so as to hold the'over-all diameter of the device to a'low value for aparticular casing size. I

The stop sleeve l5, as'explainedin detai1 ;.belo w, forms a thrust member forexerting an upwardly directed force on the upper collar IE], but this sleeve does not exert any direct forceuponthe lower collar ll. Instead, a stop collar [1, iSPIovided below the lower collar, being separated therefrom by a predeterminedamountbyjcircumferentially spaced interconnecting bars-"or straps I B'that a're butt-welded to the opposed ends of the lower collar I l and: stop collar 11. The straps preferably-do not extend. outwardly beyond the peripheries of the lower collar and stop collar, and are thinner than thezcollar thicknesses themselves; so as to provide a shoul-' der I9 on the inner edge of the stop coll'ar l1 against which a downward force may be exerted upon the casing centering device, as explained more in detail below. The interconnecting: bars 18 serve to hold thelower collar l l and stop collar IT in a definite'spaced relation-the bars I 8 transmitting any downward force exerted on the stop collar I! to the lower collar H. Y I

The centering device is mounted on a casing string, and preferably is mounted in associa'tion with upper and lower adjacent casing sectioiis' B, C that are interconnected by a suitable-"coupling D. The coupling not only serves to hold the upper and lower sections B, ,0 together, but it also functions as a stop ring, to transmit the longitudinal movement of the casing string to the centering device, exerting a, pulling action on the bowed springs l2, regardless of the direction of longitudinal movement of the casing in the well bore. As disclosed, the centering device. is mounted on the casing string, with th coupling D disposed between the lower stop collar l1 and the lower end 28 of the stop sleeve I5. When the casing string is moving in a downward direction (Fig. 2), the lower end of the coupling D engages the stop collar shoulder l9 and movesthe collar ll downwardly. This downward movement is transferred through the interconnecting bars [8 to the lower spring collar H and since the lower ends of the springs l2 are secured to this collar, the net result is that-anaction is exerted on theoutwardly bowed springs pulling them through, restrictions in; the. well bore, rather than pushing them through such restrictions. As' is well known, a. pulling action exerted on the outwardly bowed springsfacilitates their passage through. the restrictions and minimizes the possibility of breaking or permanently deforming such springs;

Similarly, in 'the event that the casing string is moved in an upward direction, the upper end of the coupling D will engage the: lower end 25! of the stop sleeve: 15,. which; extends slightly be- "low the lower collar H, the. upward force being transmitted through thissleeve to the upper collar I9. Sincetheupper ends of the bowed'springs [:2 are. secured to thislatter. collar, the. net: rei sultL-is: the exertion of. a pullingv action on the outwardly bowed springs IZ'd-uringupward'movement of the casing and centering devioein the wellborer "the stop member D is disposed; longitudinally to 7 one side ofthe bowed springs. 1-2; and that it:will,

therefore, not interfere with the: inward collapsi 'ng of such springs fiatwise against thethrust sleeve [5' tov their. minimum effective diameter,

as when the centering device is being pulled through-comparatively small restrictions, suchas might-be afiorded by an encompassing stringof casing (not shown). r

If the casing coupling D, or corresponding stop 'ring member, were disposed between upper and lower spring collars, the springs would be collapsed inwardly against the coupling itself. 'Since this coupling ordinarily has athickwall,

the: springs could. not be collapsed inwardly to as'great an extent, as when collapsed against the relatively thin sheet metal stop sleeve l5 illus- .tnatedin the drawings. This sleeve l5-need mere- I ly be made thick enough to transmit the force between the coupling D and the upper collar l0 necessary to pull the springs l2 through restric- 'tionsrin the well bore. Moreover, since the stop sleeve 1:5 extends completely between the upper and lower collars W, H, the collapse or the bowed springs [2 against them to the maximum extent precludes bending of the springs around sharp corners, and the like, such as would be afforded by the ends of the coupling, if such coupling were disposed between the upper and lower collars. This latter bending action could be productive of permanent deformation and breaking of the springs. In the present case, there are no protuberances on the sleeve 15 against which the spring can bear.

Since the springs l2 are removed from contact with the coupling D, or corresponding stop device, they cannotbe forced inwardly into binding engagement with such coupling or stopdevice. As a result, when it is desired to rotate the casing in the well bore, such rotation can occur without fear of dragging the centering device and its springs l2 around the wall of the well bore, which might. result in damage to, or destruction o f, the-casing centralizer. With the arrangement disclosed, rotation of the casing string within the centralizer-is facilitated, since there is a smooth bearing-like contact between casing section B and the inner wall of the stop sleeve I 5. In addition, the ends of the coupling D make a smooth surface; contact. with ei ihfir'the lowerstop collar H; or the-lowerend .9 o t e; s op. sleev In order to facilitatemounting of the'centering device on the casing string, the various collars H), H, I! and stop sleeve 15 can be made sectional, as by forming each of them in twoparts. Thus, the upper collar l9 and the stop sleeve 15 welded, to it are each composed of two corresponding, and preierablyequal', pieces, the-sections of the upper collar being. secured to one another by a suitable hinge 2i, inwhich the opposed hinge plates 22 are welded'to the: collar sections, and in which a hinge pin; 23 secures the plates together; Similarly, the lower collar H and stop collar H" are each made in two equal parts, such parts being; hinged together in essentially the same manner as the upper collar by hinges having their respective-pivotal axescoim cidingwiththe axis of theupper-collar hinge pin 23. V T v On the opposite side of eachcollar Iii, H, il, a. similar hinge 21a may be used for securing the parts of eachcollar together In assembling the device on a casing string, the three hinge pins 23 on one; side of the centralizer, if disposed within the knuckles. of the hinge plates 22, are-removed, which allows the cent a zer to be neop n b t comm axes of the remaining hinge pins on the opposite side, of the centralizer. The centralizer can then 7 be, placedjtransversely over a casing string B, C

substantially circumferentially continuous collars H), ll, 11 and stop sleeve l5, all properly assembled on the casing with the coupling D in position to'engage the lower stop collar ll, when the'casing string is moved downwardly, and in' position to engage the lower end 20 of the stop sleeve (5 in the event the casing string is moving in an upward direction. Accordingly, a pulling action is exerted on the bowed springs l2, regardless of the direction of travel of the casingwstring longitudinally through the well bore. Fora particular thickness of bowed spring l2, the arrangement illustrated allows the centering device to have a lesser minimum spring collapsed diameter than if the casing coupling D were. disposed within the springs and between the upper and lower spring collars IE3, H. To obtain: a proper centering force of the springs upon; the

' act-8,944

assesses, the megawatts sprees Show be made substantially greater than the thickness of the interconnecting'bars l8, since the latter are in tension in transmitting the pull between the stop collar I1 and lower spring collar H and i can be made comparatively thin. As a result, the minimum diameter of the device is the diameter across the interconnecting bars; whereas, the disposition of the coupling within the bowed springs I2 would result in the minimum diameter being the diameter across the springs, which are thicker than the "interconnecting bars, when collapsed flatwiseagainst the coupling- As a practical matj and secured to oneof said collars; and a second I ing flatwise against the collar unless the springs were broken or permanently deformed.

The inventor claims:

1. In a centering device for well conduits: an

tween and secured to said collars; a first stop member disposed outwardl of one of said collars; means securing said first stop member to said one collar; and a second stop member secured to the other of said collars and extending into, and movable longitudinally with respect to, said one collar.

3. In a centering device for Well conduits: an upper collar; a lower collar; circumferentiall'y spaced outwardly bowed leaf springs disposed between and secured to said collars; a stop collar below said lower collar; means connecting said stop collar in longitudinally spaced relation to.

said lower collar; and a stop sleeve secured to said upper collar and extending downwardly into, and movable longitudinally with respect to, said lower collar.

4. In a'centering device for well conduits: longitudinally spaced collars; circumferentially spaced outwardly bowed leaf springs disposed between and secured to said collars; a stop member disposed outwardly of one of said collars; means securing said stop member to said one collar; and a stop sleeve secured to the other of said collars and extending into, and movable longitudinally with respect to, said one collar.

5. In combination: a conduit having stop means thereon; longitudinally spaced collars disposed around said conduit to one side of said stop means and movable longitudinally with respect to said conduit; circumferentially spaced outwardly bowed leaf springs disposed between and secured to said collars; a first stop member on one side of and engageable by said stop means and secured to one of said collars; and a second stop member on the other side of and engageable by said stop means and secured to the other of said collars, said second stop member extending along and being movable longitudinally with respecttosaid one collar.

"6. In combination? a conduit having stop means thereon; longitudinally -sp'acedcollars disposed around said conduit to one sideof said stop means and movable longitudinally with re- .spect. to said conduit; circumferentially' spaced outwardly, bowed leaf springs disposed between and secured to said collars; a'first stop member on one side of and engageable by said stopmeans stop member secured to the oth'er of said collars 'and extending into and movable longitudinally with respect to said one collar, said secondstop member terminating on the otherside of and jbeing engageable by said stop means.

7. In combination. a conduit having stop means thereon; longitudinally spaced collars disposed around said conduit to one side of said stop means and movable longitudinally with respect to said conduit; circumferentially spaced outwardly bowed leaf springs disposed between and secured to said collars; a first stop member on one side of and engageable by said stop means and secured to one of said collars; and a sleeve secured to the other of said collars and extending into and movable longitudinally with respect 7 to said one collar, said sleeve terminating on the other side of and being engageable by saidstop means.

8. In combination: a conduit including upper and lower sections secured together by an intervenin coupling; longitudinally spaced collars disposed around said conduit to one side of said coupling and movable longitudinally with respect to said conduit; circumferentially spaced outwardly bowed leaf springs disposed between and secured to said collars; a first stop member on one side of and engageable by said coupling and secured to one of said collars; and a sleeve secured to the other of said collars and extending into and movable longitudinally with respect to said one collar, said sleeve terminating on the other side of and being engageable by said coupling.

9. In a centering device for well conduits: a first sectional collar; a second sectional collar longitudinally spaced from said first collar; circumferentially spaced outwardly bowed leaf springs disposed between and secured to said collars; a first sectional stop member disposed outwardly of said first collar; means securing said first stop member to said first collar; a second sectional stop member secured to said second collar and extending into, and movable longitudinally with respect to, said first collar; and detachable means securing the respective sections of said collars and stop members together to enable transverse mounting of said centering device on a well conduit.

10. In a centering device for well conduits: a first sectional collar; a second sectional collar longitudinally spaced from said first collar; circumferentially spaced outwardly bowed leaf springs disposed between and secured to said collars; a first sectional stop member disposed outwardly of said first collar; means securing said first stop member to said first collar; a second sectional stop member secured to said second collar and extending into, and movable longitudinally with respect to, said first collar; and hinge means securing the respective sections of said collars and stop members to each other.

11. In a centering device for well conduits: longitudinally spaced collars; circumferentially epaqeq twardly bow d: leai. e ings. disposed between and secured to said cqllars; a first stop member d s oeed utw y ,Q 'Qn of sa co l mane e u ing said first sw op member t said 911 col a -g and a s Q n stop m m r r d to the othe of said c l a s, and te n ing adiaqent said onev collan, Said second stopmember bein ovab e ongit dinal with resp t tQ s i Qn q 1@ nd bein lengitudi al ali n nt wan said splrm e.

12.. I e t rin dev ce fo well. condui s:

long tu in y spa e col ars; rcumi xe t al y spaced; qutwardly bowed leaf springs disposed bew n. and u d o' s idp l ars; t p m e is es d, qutwarmy or one of said colla s; mean Securing is p member to. said" Qn j coll r; and

e p sleeve seeunexi 0 e. ther Qt. sa d, ll

' 8 and termi a n a acent: sa d, 20 1 1 3,; sai ep sleeve. being mn ab e lon itudinally w th espect 11,0. Said one collar.

CLARK. JE-

REFERENCES CITED Thef o ll owing references, are of rrecglidv in the file of this patent:

UN T D STATE PA EN 7 Date

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