US2490350A - Means for centralizing casing and the like in a well - Google Patents

Description

3 Sheets-Sheet 2 INVENToR.

rroe/vfy GRABLE D. B. MEANS FOR CENTRALIZING CASINGS AND THE LIKE IN WELLS Filed Dec.

Dec 6, 1949 D. B. GRABLE 2,490,350

MEANS FOR CENTRALIZING CASINGS AND THE LIKE IN WELLS 3 Sheets-Sheet .'5

Filed Dec. 15,. 1943 INVEVTOR.

,Qimmy m AM\.` f Aol/1 me Patented Dec. 6, 1949 UNITED STATES PATENT GFFICE MEANS FOR CENTRALIZING CASING AND THE LIKE IN A WELL Application December 15, 1943, Serial No. 514,368

16 Claims.

This invention relates to apparatus for centralizing and laterally supporting a string of casing in a well bore, such as an oil well. In this connection casing is to be understood in the broad sense, as covering any string of tubing, piping or the like extending downwardly in a Well bore and which it may be desired to centralize therein.

It is an object of the present invention to provide a method and means for centralizing and lsoupporting a string of casing centrally in a well ore.

It is another object of this invention to provide such means which does not interfere with removing the casing from the hole if desired, which has no tendency to collect mud cake or foreign matter during the operation of running-in the casing and which allows free manipulation of the casing in either direction, at least until the centralizer has been tripped.

It is another object of this invention to provide a casing centralizer which is positively maintained free of the wall of the well bore until tripped or activated by the operator at the mouth of the well.

It is still another object of this invention to provide a casing centralizer wherein, after the initial tripping or activation of the centralizer, manipulation of the casing string serves to cause the centralizer to apply a centering force to the casing.

It is another object of this invention to prov vide a casing centralizer wherein a positive indication is given to the operator when the centralizer is tripped or activated.

It is still another object of this invention to provide casing centralizing means adapted to be placed at spaced points along a pipe string.

It is still another object of this invention to provide a series of centralizers or supports along a casing string arranged to be operated in sequence at desired time intervals, or selectively as desired by means controllable by the operator.

It is still another object of this invention to provide a casing centralizer which requires no openings through the wall of the casing establishing communication between the space within the casing and the space outside the casing, and hence is adapted for use on a string of solid tubing or casing.

It is a further object of this invention to provide in one modication a casing centralizer adapted for operation by hydraulic pressure, such las isreadily obtainable from the circulation pump usually provided in connection with the hydraulic drilling of a well.

It is a further object of this invention to provide, in another modification, a casing centralizer arranged to be tripped by mechanical means operable from the mouth of the well.

It is a further object of this invention to provide in still another modication, a casing centralizer adapted for operation by cable tools, a wire line, or the like.

In its broad aspects the invention comprises means for positioning a plurality of members carried by the casing and spaced about the periph- -ery thereof between the exterior of the casing string and the wall of the well bore, causing said members to engage the wall, and then causing said members to exert a lateral force on the casing urging it toward the center of the bore.

This invention possesses many other advantages and has other objects which may be made more easily apparent from a consideration of several embodiments of the invention. For this purpose there are shown a number of forms in the drawings accompanying and forming part of the present specification. These forms Will now be described in detail, illustrating the general principles of the invention; but it is to be understood that this detailed description is not to be taken in a limiting sense, since the scope of the invention is best defined by the appended claims.

In the drawings:

Figure 1 is an axial section through a well bore having a string of casing therein equipped with several centralizers such as are contemplated by the present invention;

Figure 2 is an axial section of one form of centralizer;

Figure 2-a is a cross section taken on line 22a-2a of Figure 2;

Figure 3 is a fragmentary detail section of the tripping means used in the form of the invention shown in Figure 2;

Figure 4 is a fragmentary vertical section on an enlarged scale showing the device of Figure 2 in operative position;

Figure 5 is a view similar to Figure 3, showing the tripping means after it has operated;

Figure 6 is an axial section of a modified form of centralizer;

Figure 7 shows the device of Figure 6 after tripping;

Figure 8 is a fragmentary vertical section on an enlarged scale showing the device of Figure 6 in operative position; I

Figure 9 is an axial section of a further modied form of centraliser;

Figure is a fragmentary detail section showing the means for retaining the centralizer of Figure 9 out of operative position; and,

Figures 11 and l2 show successive operating positions of the device of Figure 9.

Referring to Figure 1 of the drawings, a well bore is indicated by I and has a string of casing or tubing 2 suspended therein in a manner well understood, with centralizersA mounted thereon at axially spaced positions.. The lower portion of the well bore I is shown as deviating from a truly vertical direction, the centralizers 3 on the casing 2 in this portion of the bore serving to maintain the casing central in the bore or hole in spite of such slant. However, it is to be understood that the centralizers are not restricted to use in a slanting hole, since even in a hole which is considered truly vertical, the casing will not in general be central of the hole, due to irregu-v larities in the wall of the bore caused by the different materials of the strata through which the bore passes, and washing and caving of the wall. Furthermore, a long string of casing is not itself truly straight. Accordingly, centralizers are placed wherever it is desired to position the casing centrally in the bore, and to support it against vibration.

The centralizers 3 in general each comprise a plurality of pairs of links i8 angularly spaced about the casing and extending axially thereof, the links of each pair being connected in a toggle like manner. As clearly shown in Figures 2 and 3, these links are arranged to be normally substantially nat against the outside of the casing, and retaining means are provided for releasably maintaining them in this inactive position. Means operable from the mouth of the well are provided for releasing this retaining means and causing the toggle to jack knife or break, whereby the joined portions of each pair of links Il] are forced outwardly, at least some of these joined portions engaging the well wall I I. Since the pairs of links on each centralizer 3 are arranged to act simultaneously, the effective diameter of the centralizer will be increased, at the same time its center remains coincident with the center of the casing. Thus, as will be hereinafter explained, such engagement of links IIl with the wall I I may be utilized to urge the centralizer 34 and the adjacent portion of the casing 2A towardY the center of the well' bore I. It is to be understood thatA the link pairs Il] are so proportioned and arranged with respect to the size of the casing and the well bore, that such initial operation causes the links I to assume some position in contact with the wall II less than a fully expanded position, such as indicated by broken lines in Figure 2, means being provided to prevent return of the links toward their initial position. Since the operating links I are entirely outside of the casing their lengths or other critical dimensions and the throw or expanded diameter of the centralizer is not restricted by the size of the casing with which the centralizer is used. Thus, a slight upward movement of the casing, referring to FigureV 2, will cause the drag of the links on the wall II to urge them toward a more expanded position, the resultant wedging action between the casing 2 and the wall II exerting a force centering the casing in the hole as well as supporting the casing against vibration.

Referring more in detail to that form of the invention shown in Figures 2 to 5, a sleeve I 5 is fixed on the exterior of the casing 2 in any convenient manner as by welding. Each pair of toggle links Ii) comprises a centering link I6 pivoted on the sleeve I5 at I'I and an expander link I8 pivotally joining a collar I9 slidable on the sleeve I5 with the free end of the link I6. Axial movement of the collar I9 on the sleeve I5 serves to swing the links I5 about their pivots between the inactive position shown in solid lines in Figure 2 and the fully expanded position of Figure 4. It is to be understood that the links Il) do not necessarily assume the fully expanded position of Figure 4 to effect centering of the casing, the amount of expansion of links I depending on the diameter of the well bore and on the character of the wall ol the well. As a means of retaining the links II) in inactive position, a circumferential boss 2Q is provided on the sleeve I5, links I8 being secured thereto by a frangible connection such as a bolt 2l. The bolt 2| may have a portion 22 of reduced diameter; by providing bolts 2| of different materials or having reduced portions 22 of diierent diameters, the force required to release the links I0 may be adjusted.

For providing such force, one or more plungers such as indicated by 25 (see Figures 3, 4 and 5) are arranged to be forced outwardly against the links I8 by hydraulic pressure within the casing 2. The plunger 25 is slidably mounted in a suitable cylinder 26 extending through the casing 2 and the sleeve I5, and has a packed head 21 anda stem 28. It will be obvious that pressure within the casing will force the plunger outwardly, stem 28 engaging the link I8. When such pressure reaches a sucient amount, the bolt 2I will be broken at its reduced portion 22, allowing the link I6 to be swung outwardly in response to downward movement of the collar I9. Such movement is caused by a compression spring 30 confined between the collar I9 and a suitable stop 3l on the sleeve I5. For preventing return of the links I0 to their inactive position after their initial expanding movement, ratchet teeth 32 are provided on the sleeve I5 for cooperation with the spring pressed dogs 33 pivoted on the collar I9.

It is believed that the operation of the centralizer will be understood from what has been set forth. Pressure within the casing 2 is increased to a suiicient amount to cause the plunger 25 to force the link i8 outwardly and free it :from the retaining means by fracturing the bolt 2|. The

links IIJ are then swung outwardly by the spring 3D, at least some of the links engaging the wall II as shown by the broken lines of Figure 2. Upward movement of the casing 2 then causes a centering force by urging the links I6 outwardly toward the full line position of Figure 4.

It is essential that a free passage be provided down the casing for circulation to wash the hole clean before starting the cementing job, and further that the casing be free for raising and lowf ering to assist such washing. It is apparent that the casing is entirely free for such up and downV movement as long as the centralizer is in its unexpanded position. To maintain such free passage as well as to provide means to make possible the necessary increase in pressure to trip the centralizer, valve means are provided in the casing just below the plunger 25. This valve means comprises. a ported plate 34 of some material of limited strength and quite readily destructible, for example, cast iron, natural or articial rubber, or a phenolic condensate secured at its edge in a metallic ring 36 arranged to be confined between the ends of adjacent sections of the casing 2 a short distance below the plunger cylinder 26. The port 31 in the plate 33 is of suiiicient size to permit free circulation of fluid in the casing 2.

When it is desired to trip the centralizer a ball 38 of suitable material such as cast iron, and of suflicient size to close the port 31, is placed in the casing 2 and gravitates downwardly with the circulating fluid. When the ball 38 reaches the plate 34, it closes the port 31, -permitting pressure within the casing to be increased suiciently to actuate the plunger 25. Further increase of pressure serves to break the plate 34 and release the ball 38 for further movement down the well. This arrangement permits the successive operation of a series of centralizers 3, as shown in Figure 1. Thus, a ported plate or diaphragm 34 is provided below each centralizer. As these plates are successively fractured, the ball 36 drops to the plate 34 next below, allowing pressure to be built up to operate the associated centralizer. It is intended that the diaphragme 34 be so arranged as to split into several segments upon fracturing, these sections hanging from the ring 36 in a manner as indicated by the broken lines of Figure 2, and as shown in Figure 4, so as not to obstruct circulation through the casing or the passage of conventional cementing plugs. For this purpose a plate with a plurality of radial grooves or portions of reduced thickness is provided, indicated by 35 in Figure Z-a.

For example, the frangible pin 2l can be proH portioned to break at a pressure within the casing of 250# per sq. in. above the normal circulation pressure, which pressure .can be readily ascer tained, as being a function of the depth and other known conditions of the well. On the other hand, the plate 33' can be arranged to fracture under a pressure of say 500# in excess of the normal cir-A culation pressure. By appropriate gauges at the mouth of the well, the operator can readilydetermine when each of these operations, viz., the breaking of pin 2l, tripping of the centralizer, and the fracture of diaphragm 3ft have been accomplished. This is of great advantage.

It is possible to provide for selective operation of the centralizers by providing diaphragme 3ft having different sizes of ports 31, and utilizing balls 38 of appropriate sizesto respectively cooperate with such ports. Further, by omitting these diaphragms 34 and providing a solid diaphragm below the last centralizer, the centralizers can be tripped substantially simultaneously, since this arrangement makes possible the operation of all plungers 25 at the same time. It is to be understood that such a diaphragm is of readily destructible material as before, so that after trpping the centralizers, the well pressure is built up to fracture the diaphragm and establish a free passage through the casing for circulation or the passage of cementing plugs.

To prevent leakage of iiuid between the inside of the casing 2 and the surrounding space, the plunger 25 is provided with a conical back d3 adapted to engage a conical seat il in the cylinder 26 when the plunger 25 is in its outermost position (see Figure 5). However, it is not essential that the plunger 25 be in contact with the seat Ill to prevent leakage, since the packing carried by the plunger head 21 is adequate to prevent leakage between the head 21 and the wall of the cylinder 26 in any case. A cap 112 having spring iingers 43 is suitably secured on the outer end of the plunger stem 28, and when the conical surfaces 46 and 4I come into contact, the ngers d'3 spread and engage the outer end surface 34 of .the cylinder 26, maintaining the plunger in seated position. To prevent the plunger 25 being blown out of the cylinder 26 into the casing 2, a snap ring 26-a is provided in a suitable groove near the inner end of the cylinder 26. By engaging the head 21, this serves to limit inward movement of the plunger.

It will be obvious that the centralizing mechanism disclosed in Figures 2 to 5 may be inverted if desired, that is, with links I6 pivoted to the casing 2 at the upper end of the sleeve I5 and above the collar lil, the latter being arranged to move upwardly in response to release by the plungers 25 to swing the links i6 outwardly. With a centralizer arranged in this manner, the casing 2 is lowered to increase the centering force exerted by the links I6 instead of raised. This may be advantageous under some operating conditions.

Figures 6, 'l and 8 show a centralizer similar to that just described but with another form of tripping mechanism to permit its use on perforated casing, parts corresponding to those in the previously described form being indicated by the same numerals with the addition of the letter 11. Frangible pins or rods 50 are provided as before for retaining the wall engaging links in collapsed or inactive position, but in this form oi the invention the pins 56 extend through suitable openings 5I, 52 in the casing 2-a and the sleeve l5-a, downwardly and inwardly of the casing, and are connected to and support a ring 53 axially of the casing. The ring 53 is also connected with the collar |9--a by several flexible elements 5s, such as light steel cables, extending through openings 55 in the casing Z-a and the sleeve I5-a. As shown in Figure 6, before tripping the device, a small amount of slack indicated at 56 is provided in each cable, whereby a lost motion connection is formed between the ring 53 and the collar lS-a. Thus, sufficient downward movement of the ring 53 to break the rods 56 before moving the collar I9--a is provided.

Downward force for moving the ring 53 is provided by a string of tubing or drill pipe 5l, operable from the mouth of the well. This tub ing carries a spear 58 at its lower end, having a pair of spring urged pivoted fingers 53 arranged to swing inwardly against the force of the spring to permit passage through the ring 53. A stop collar 69 on the spear 58 serves to transmit downward movement of the spear to the ring 53.

AThe operation of this form of the invention is as follows. Spear 58 is inserted downwardly through the ring 53, lingers 59 swinging inwardly to permit such insertion, until the ring 53 is engaged by the stop collar 66. Downward force on the tubing 51 and the spear 58 will now be supported by the rods 50, and upon such force reaching a suiiicient amount, these rods will be pulled in two, allowing the ring 53 to move downwardly until the slack istaken out of the cables 53, whereupon downward force will be transmitted to the collar I 9-a, causing the links l6a to swing outwardly to engage the wall l I-a of the well. With this arrangement force may be applied by the operating means 51 to expand the centralizer to the limit of its movement. 0r, upward movement may be imparted to the casing 2-a serving to wedge the links I6--a between the casing 2-a and the wall Il-a as before.

After the links |6-a have engaged the wall l I-a,additional downwardforceisaappliedltothe spear 58 serving to break thecables:-E4;'after which the spear 58 together with-the ring'and the pieces of the rods 50 andI of 'thecable's 54 attached thereto may be removed from the lwell, the lingers 59 serving to retainthe ringv 53 onthe spear. Or if a series of centralizers are.' used; as in Figure l, the spear 58 maybe-lowered `'until the ring 53 of the next' centralizer,l is fengaged, when the tripping operation is repeatedfthis ring being on the spear below the flrstfringf53. Continued downward travel ofthe/spearserves to successively trip the centralizers 'After-they have all been tripped, the tubing` B'Iandwthe spear 58 together with all the rings-53 andjattached pieces of rods' 56 and of cables 54 maybe removed from the well.

The casing centralizer may be fur-ther modified so as to be tripped and'opened to wallengaging position by a member moving upwardly-'ofthe casing, making possible the use of the fldevice with cable tools, or its operation by'a cable. Such a modification is shown in-'Figures 9:to''12.

As shown in Figure 9, the centralizer,except for the tripping mechanism, is practically the same as that of the previously described -forms but is inverted. Thus, a sleeve 65 is fixed on lthe casing as before, the centeringlinksf being pivoted thereto lat 6l. Expander links681 serve to operatively connect the links"66=with-avcollar 69 axially slidable on the sleeve 65. In thisica'se, upward movement of the collar 65 serves to swing the links 66 into operative position. A1 spring l is provided to urge the collar` 69aupwardly;l a

ratchet mechanism l! similar to. that f of the rst form being-arranged to permit free upward movement of the-collar 69 to expand thecentralizer but to prevent reversemovem'ent of*v the collar and reduction in diameter of the .centralizer.

The tripping mechanism comprises'awringfS within the casing 62 and connectedqtolthe expander links 68 by frangible or shear. pins-'14 which pass through suitable openings A'i54 through the casing 62 and sleeve 65. The'ring. 13 is also joined to the collar 69 by a Vnumber'ofmlight cables 'l' which pass upwardly `from Vthering'lS through openings Il in the'wall of-theacasing and downwardly to the point of connection VMiron the collar 69.

It will be apparent that upward movement. of the ring 13 from its initialposition (Figures 9 and l0) will rst bend the pins or rodsl 14' andthen break them, releasing the links. 65,; Gil-:and slacking the cables '15, as shown in Figure 11. l The collar 69 may or may not Vbe moved upwardlyj-by the spring Hl to expand the centralizer-pdepending on various conditions. Inanyf caseg-,lcontinued upward movementv of the ring;13-fwi1l rst pull the cables 16 tightand then pullthe collar 69 upward causing the linksto swingoutwardly, the parts assuming the relativegpositions of Figure 12.

A spear 80 having pivoted 'ngersl urged apart by a compression Vspring 82 providesrupwardly directed shoulders 83'for engaging the ring 13. Spear Seis shown as connected tofafconventional set of jars 84which inturn is.connected to a sinker bar and cable, not shown. In operation, the spear 80 is lowered until'it 'contactsithe ring 13, the weight of the jars-and sinker'bar cooperating with the ring 73 to cause thedinge'rs to be pressed togethertolallowfthem to'pass through the ring. The ngers then rInovetapart to provide-the shoulders- 8-3l under 'the ring-'I3 8 1ias'ffx-sli'own'-#ini1Figures11 and 12. Upward movement of Y"che spear '80` by i the attached cable .will then-moveitheiring 1li-upwardly' with the results ljust` explainedw 'However, continued upward 'movementlfof the cable andk spear 80 after-,the links`.f66;68.have-swung outwardly to the limit of their movement will part the cables 16,allowing thefring-'l'3together withthe remnants of the p'insLM-vandicablesll2attached thereto to be removed; from thecasing with the spear. `"uIhis-f'formfof*centralizer can also be used' at spacedp'ositions and tripped-successively by the :speari: Iny such a casefthe-spear must belowcredito .trip the uppermost centralizer first, and thenbe-pulled upwardly in theV casing to remove -thesringfl3as just explained. The spear 80 is then :loweredtozengage the 4ring 13 of each successively. lower centralizer, severing the, pinsrld .land-:cables 16 connected therewith and removing thelringa as `justfpointed out. When the centralizersf have all 1been-tripped and the operation completed; :the rings 13 of all the centralizers with the' pieces of vpins 'I4 and the cables 16 con- -nectedthereto will have been removed from the :well-,z fleaving 'the inside of the casing clear for further operations.

4',-fIs'he .pullon the cable can be used to force the centering-links 66 aga-inst the well wall to center -the,casing, orthisA force can be supplemented by movementV of fthe; casing 62, as before. .xHowever, in this1case; the casing must be lowered for this purpose. fIn-the event thattheA centralizer is usedxon aliner,;a pull-,on the cable must be relied on to iorce-,thev-links 66 against `the wellwall to center the liner if the liner has been hung fand cannot ,be moved upwardly or downwardly, this being the routine method of landing perforated liners. If, however, the liner is free or has not been hung, it may be moved axially downward to provide this force or to increase it. By appropriate use' of a weight indicator in connection withI the cable, the operator can determine when the frangible pins 14 are broken, when the cables 16 arev Ipulled apart, and other important operating data.

It is not essential that the spear 58 or 80be run in the-hole on tubing or cable especially for the purpose of tripping the centralizers. They could be .placed-on drill pipe tubing, or a string of cable tools, with various types of'delayed action setting tools, washing tools or the like and removed- `from the holes as the other tools are removed.

- 1. -A` casing centralizercomprising an expansiblespider, including a collar slidable with respect to the casing and a plurality of members mounted von'saidV casing and operatively connected with said-collar soas to move outwardly from-the casing-'in-response to movement of said collar in onefdirection, means urging said collar to move in said direction to cause said members to move outwardly, -f-rangible means maintaining said membersin retracted position, and means -extending through the walls of the casing and operablefrom within the casing for fracturing saidfrangiblemeans and releasing said members to move outwardly from the casing inresponse to movement of said collar.

" 2: A casing'centralizercomprising an expansible spiderl adapted -for mounting on the casing, said spider'including a sleeve adapted to besecured tov the casing, a collar slidable with respect tothe casing, and a-plurality of axially extending toggley linkages,- each` of whichis pivotallysecured `9 at one end to said sleeve, the other ends of said linkages being attached to said collar, means urging said collar to move in a direction to swing said linkages outwardly from the sleeve, frangible means maintaining the links of each of said linkages substantially aligned, and means operable from within the casing for fracturing the frangible means, whereupon said linkages are swung outwardly from the casing.

3. A casing centralizer comprising an expansible spider adapted for mounting on the casing, said spider including a sleeve adapted to be secured to the casing, a collar slidable with respect to the casing, and a plurality of axially extending toggle linkages, each of which is pivotally secured at one end to said sleeve, the other ends of said linkages being attached to said collar, means urging said collar to move in a direction to swing said linkages outwardly from the sleeve, frangible means maintaining the links of each of said link ages substantially aligned, means operable from within the casing for fracturing the frangible means whereupon said linkages are swung outwardly from the casing, and means operating to prevent movement of the collar in a direction to swing said linkages inwardly toward the casing but permitting movement of the collar in a direction to swing the linkages outwardly from the casing.

4. A casing centralizar comprising an expansible spider adapted for mounting on the casing, said spider including a sleeve adapted to be secured to the casing, a collar slidable with respect to the casing, and a plurality of axially extending toggle linkages, each of which is pivotally secured at one end to said sleeve, the other ends of said linkages being attached to said collar, means resiliently urging said collar to move in a direction to swing said linkages outwardly from the sleeve, frangible means maintaining the links of each of said linkages substantially aligned, means operable from within the casing for fracturing the frangible means, and means forming a lost motion connection between said means operable from within the casing and said collar, whereby said lost motion means after fracture of the frangible means, acts to move said collar to urge said linkages to swing outwardly.

5. A casing centraliser adapted for use on a fluidtight string of casing, comprising a member mounted exteriorly on the casing for movement outwardly with respect thereto to engage the wall of the well bore, and means extending through the wall of said casing in a fluidtight manner, responsive to fluid pressure in the casing for causing outward movement of said member.

6. A casing centraliser adapted for use on an imperforate string of casing comprising a member mounted with respect to the casing to move outwardly from the casing and engage the wall of the well bore, and a plunger mounted in the wall of the casing and movable transversely of the casing in response to fluid pressure therein to engage the member and cause outward movement thereof.

7. A casing centraliser adapted for use on an imperforate string ci casing comprising a membei: mounted with respect to the casing to move outwardly from the casing and engage the wall of the well bore, frangible means retaining said member out oi wall engaging position, and a plunger mounted on the wall of the casing and movable transversely of the casing in response to fluid pressure therein to engage said member -10 and fracture-said frangible means', causing outward movement of said member.

8. Casing centralizing means comprising a plurality of 'sets of members mounted at axially spaced points along the casing, said members being arranged to move outwardly lfrom the casingA and engage the wall of the well bore in response to uid pressure within the casing, and valve means associated with each set of members for controlling the application of pressure thereto, said means comprising a ported diaphragm extending across the casing adjacent each of said sets, and means for closing the port.

9. Casing centralizing means comprising a plurality of sets of members mounted at axially spaced points along the casing, said members being arranged to move outwardly from the casing and engage the wall of the Well bore in response to iiuid lpressure within the casing, and valve means associated with each set of members for controlling the application of pressure thereto, each of said valve means comprising a yieldable structure adapted to close the casing, said structure being adapted to yield responsive to a, rise of pressure to a predetermined amount for applying pressure to a succeeding set of members.

10. A casing centralizer comprising a member mounted with respect to the casing to move outwardly from the casing and engage the wall of the well bore in response to fluid pressure within the casing, and valve means in said casing for causing said pressure to be ,effectiveon the member, said valve means including a diaphragm member and a closure member adapted to cooperate to close the casing space below the member, one of said members being adapted to yield responsive to a rise in pressure to permit fluid to spass freely through the casing.

11. A casing centralizer for use in a well, comprising a pair of links connected to form a toggle linkage, movement of the free ends of said linkage toward each other serving to swing the links outwardly fromy the casing to engage theV wall of the well bore, means pivotally securing one free end of said linkage to the casing, and

a collar slidably mounted on the casing to which the other free end of said linkage is pivoted, and means for moving said collar axially of the casing toward said pivotal securing means, comprising a memberwithin the casing, means securing said member to said collar, and means operable from the mouth of the well `for shifting said member to move said collar toward said pivotal securing means.

12. In a casing centralizer for use in a well, comprising a pair of links connected to form a toggle linkage, movement of the ends of said linkage toward each other serving to swing the links outwardly from the casing to engage the wall of the well bore, means pivotally securing one end of said linkage to the casing, a collar slidably mounted on the casing to which the other end of said linkage is pivoted, a member within the casing, a frangible connection between said member and one of said links to maintain said links in retracted position, means forming a lost motion connection between said member and said collar, and means operable from the mouth of the well for moving said member, movement of said member in one direction serving rst to break the frangible connection and to then move said collar to swing the links outwardly.

13. In a casing centralizer for use in a Well, comprising a pair of links connected to form a toggle linkage, movement of the ends of said linkaseftowalzd; eaQhpther-Servineto Swine the; Alinksoutwardly from the .caslnfggto:engagethe-.walroi theme11 b J re,mea-n s pivotally-securing Aone end ofqsaid linkage to4 the, casing, a -jcollar -slidably mounted on` the .casngto whichjtheotlier endofl 5 saidlinkageis p ivoted, amemb'er wit-hintlie casl;

a frangilolev connection between said mernber andf .on e o f said .linl -:s .to, .maintain` said links inr retracted position,A means` forming -a ylost motion. connection.betweensaidfmember and said-collar 10I arranged, to fract1 1`r e 1n response@ to la ,1:rede termied v force, and4 Emeans l operable from the mouth ofthe Wellandlaving opposedsnoulders for coniining Vsaid membenfmovement i of;A said means in oneV direction, causing said memberto 1,-,

move-to flr'st breakthe-frangibl'e ,connection and then cause'the collar ,tovswingg-the link-s outwardly,- continued Y movement, of; ;sa id means serving to fracture 2 said llost. motion. fior-ming means and` thereby" .di soonnect said collamandlsaid member; ,y. movement of said n ieaiisV in the opposite direction thereafter 1emving'5th'e member from the casing. A14. Inf, apparatus ,for .centralizing a casing; -inT a well" bore,- a plurality ,Lof h casing centralizers mounted at, axially` ac'edpoints along-the cas- :5 ing,' each central neludingia pair'iof -links cori'r'lecteizllY togetllier tofoifm a toggle. linkage, mvfr'nt*J of 'the` 'ends- 'ofsaidv .linkageltowardl eahil other, serving `.to` 'swiig';.th`e links outwardly from fthe casing to'` engagethelwall oi .the well; 30 bQije" 'mial'LI- piolly "s'e` ,one end. --Saidres'pbtively `se :`1',1r ed,,to each `of jlsaidcollars, and 35 means ,operable"fronigtheinutb of ,thelwell for successively Engaging; anameving said" members 1 in 'responseito move'I rler'il'f,fY said last mentioned means inane direct10'Whe1teby said. Collars are' moved to'cause the links oiifsicces'slve'centralizers 40 to. swine .outwardly from the ,Casin 15f.,m'animas"forcenirai ,emanen a well bore, a jpluralityfof casing;V centralizer'sA mQuQted at. .axially spaced points, .alonegthecasing`, f`eat`:h A c entralizer ncludng a A pair" of links 45 CQIslQte'd 5 tog'ethl '40. fQrnila toggle, linkage.,VV movementjof meen-1epf saidlangageomariife'aehV otlierserving tot swi'n "the flinks 'outwa'rdly from thellcasing to engag he Wall 'of vthe wel l bore,. m'lfls pvo'tallyseour gfAthQQIOWQrGHdff 'Sait'550 linkage"' -to ffthe` casing 'and'. colla1 f `slidably m tbnifhcane A111127011111121 endjpf Said llriliages. ,pivots-f... a prality' OfilmmbelS respectively seeuredsto eeen-f said collars-jana meansgoperable;fromfthe -mouth-v of -the well l'fork successively engaging andmovi-ng said Imembers inresponse to movementof said last mentionedy means Y downwardly, whereby-v said collars are moved to cause thelinks-ofsuccessive centralizers to swing outwardly from the casing.

16. In apparatus for centralizing `a casing ina well bore, a plurality of casing centralizers mounted at axially spaced points along the casing,eaoh vcentralizer including: a pair of links connected' together; to-form a 'toggle linkage,

movement of the ends of saidlinkage toward each-- otheryservingto swing-the linksgoutwardly from= the casing to'engage theV wall,V of-.the Well bore, means pivotallyfsecuringvthe upper end of said linkage `to the casing,and a collar slidablyy mounted on the casingfto which the other end.

REFERENCES CITED TheA following referencesare of record in the le of jthis patent:v

UNITEDA`v STATES PATENTS Number. Name.V Date 735,690 Alvord; Aug. 11, 1903 1,127,428 Fuq:1ua,' v Feb. 9, 1915 1,563,520 j Owen Dec. 1, 1925 1,647,630 Hyer Nov. 1, 1927 l 1,708,354 Cabot Apr. 9, 1929 1,801,334 Dalldorf` et al. Apr. 21,1931 2,009,322,1 Nelson. July 23, 1935 2,013,457 Burt Sept. 3, 1935 2,053,698'. Church` Sept. 8, 1936 2,061,316 y Braak et a1. Nov. 17, 1936 2,119,0954 Bmmmett May 31, 1938 2,177,601 Smith Oct. 24,1939 2,212,087 Thornhill Aug. 20,1940 2,253,415 Brodie Aug. 19, 1941 2,262,655 Seale Nov. 11, 1941 2,286,673 Douglas June 16, 1942 2,295,418 Mims Sept. 8,1942' 2,311,768 MCGray e Feb. 23,1943 2,313,176 Shelby-1----; Mar. 9, 1943 2,328,840 l Ollleary.V Sept. 7, 1943

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