US2727576A - Centralizers - Google Patents

Description

J. E. HALL CENTRALIZERS Dec. 20, 1955 3 Sheets-Sheet 1 Filed April 9, 1952 INVENTOR. Jase 5 flafl I i c ,4 ewsx Dec. 20, 1955 .J. E. HALL 2,727,576 CENTRALIZERS Filed April 9, 1952 I5 Sheets-Sheet 2 7 E E /5 F 2 J E???"- iyg 9 @5549 0 A OFNEK J. E. HALL CENTRALIZERS Dec. 20, 1955 3 Sheets-Sheet 5 Filed April 9, 1952 INVENTOR. dease E, flfl/ iTTOkNEK United States Patent 2,727,576 CENTRALIZERS Jesse E. Hall, Weather-ford, Tex. Application April 9, 1952, Serial No. 281,375 2 Claims. (Cl. 166-441) This invention relates to improvements in centralizer construction and refers more particularly to the design and construction of centering devices mounted on the exterior of easing or pipe used to produce fluid from wells.

In the drilling of wells, particularly oil wells, and in the conditioning of the well bore for cementing, fluids, such as slurries of mud and water, mud and oil and cement and water, are circulated in the annular passageway between the well bore and the exterior of the casing or pipe. Well tools in some instances are mounted on the exterior of the casing to center the casing in the well bore and to remove mud cake from the bore when the well is being conditioned for cementing. The mounting of tools on the exterior of the casing inevitably forms an obstruction to the passage of fluids in the annular space surrounding the casing. Centralizers usually are constructed with upper and lower collars or sleeves to which are attached bands or strips of metal extending between the collars and outbowed at their midsections to frictionally contact the well bore. By spacing the centralizers at intervals along the pipe or casing, the latter is held in a centered position in the well bore, forming an annulus or passageway of rela tively uniform radial depth around the casing for the flow of fluids.

As the size of the annulus or passageway is defined by the distance between the exterior of the casing and the well bore, any obstruction on the outside of the pipe, such as the centralizers, will form an obstruction to the free flow of fluids; and since the blades or out-bowed bands of each centralizer extend from the upper collar to the well wall and thence back to the lowercollar, each band forms a double obstruction in the fluid passageway. Therefore, any reduction that can be made in the width of the bands in their upper and lower sections will reduce to that extent the obstruction oflered to the passage of fluids through the annulus surrounding the casing. I

An object, therefore, of the present invention is to modify the upper and lower end portions of the bands or blades of the centralizer so they form less obstruction to the fluid flow around the casing without materially reducing their strength and rigidity.

Another object is to provide a simple and effective construction for anchoring the ends of the bands in the collars of the tool.

Other objects and advantages will appear from the description and explanation which follows.

In the accompanying drawings which form a part of the instant specification and are to be read in conjunction therewith, like reference numerals indicate like parts in the various views.

Fig. 1 is an end view of a centralizer embodying the invention;

Fig. 2 is a side elevational view of the centralizer shown in Fig. 1;

Fig. 3 is an enlarged detail showing the manner in which the ends of the bands or blades are split and notched for attachment to the collars;

Fig. 4 is a detail showing the manner in which the split ends of the bands or blades are spread and inserted into perforations punched in the annular bosses formed in the collars;

Fig. 5 is a detail showing the split ends of the bands or blades after insertion in the perforations of the collars with the locking appendages or tabs in engagement with the notches of the bands;

Fig. 6 is a view taken along the line 66 in Fig. 5 in the direction of the arrows;

Fig. 7 is a fragmentary edge view of a collar showing the manner in which the annular boss is formed and the holes punched for insertion of the split ends of the bands;

Fig. 8 is a perspective side view of one of the collars;

Fig. 9 is a detail showing the manufacturing procedure for perforating and forming the collars from a strip of metal;

Fig. 10 is a detail of a modified construction for anchoring the ends of the bands in the collars by locating the locking tabs on the outside of the bands instead of between the split ends as shown in Fig. 5;

Fig. 11 is an end view of a centralizer of modified construction;

Fig. 12 is a side elevation of the modified construction shown in Fig. 11;

Fig. 13 is an end view of a centralizer constructed according to a second modification; and

Fig. 14 is a view taken along the line 1414 in Fig. 13 in the direction of the arrows.

Referring to the drawings, and particularly Figs. 1 to 10, inclusive, the upper and lower collars of the centralizer are formed of a strip of metal such as is shown at 15 in The metal is perforated with slotted holes 16 at intervals along its length. A convex annular prominence or boss 15:: is formed in the midsection of each of the strips and the strips are then rolled into circular sleeves or collars shown best in Figs. 7 and 8 locating the slotted holes 16 in the upper and lower surfaces of the annular protuberance or ridge. The inside diameters of the collars are slightly greater than the pipe or casing upon which they are to be mounted to the collars will fit slidably thereon. The bands or blades of the centralizer are designated by the numeral 17 and are shown assembled with the collars in Figs. 1 and 2. The ends or extremities of these bands are drilled centrally as shown in Fig. 3 with a small hole 18 spaced a considerable distance from the ends and two larger holes 19 spaced but a short distance from the ends. Along the outer edges of the bands and near the extremities are notches 20. The bands are then split longitudinally along the line 21 to small holes 18 as shown in Fig. 3 and the split ends or legs of the bands designated by the numeral 17a spread apart as shown in Fig. 4. When the slotted holes 16 were made in the collars, the metal punched from the slotted openings was bent down to form locking appendages or tabs 16a shown best in Figs. 4, 5 and 10. It will be noted that the locking tabs or tongues punched from the collars are located to engage the notches on the inside edges of the split ends of the bands as shown in Figs. 4 and 5. In Fig. 10 they are located to engage notches located on the outside of the bands. The bands are all evenly out-bowed at their midsections to contact the well wall and hold the pipe or casing centrally positioned as shown in Fig. 2.

The split or bifurcated ends of the bands or blades are spread somewhat wider than the distance between the slotted holes 16, so insertion of the ends into the slotted openings of the collars requires constriction or pressing together of the ends as indicated in the dotted lines in Fig. 4. Upon insertion of the ends of the hands into holes 16in the annular bosses of the collars, the resilience in the legs of the bands will cause notches 20 to engage the outer edges of the slotted openings. Appendages 16a are then bent into the semicircular notches formed inside of the legszby .holes :19, zthus .anchoring the split extremities of h bands r dly in the cal ers- In hean hui g construction shown in Fig. 10, the rectangular-shaped notches are along the inside edges ofthe legs and the semicircular notches. along the outside edges. The locking appendages 16a :in this constructionare located to .engagethe semicircular notches along the outside edges while the rectangular notches are engaged by'theredges of the slotted openings 16. It .has1also .been found advisable -.to .bend :back the top and bottom edges of the collar .in the form of abutment rims as shown at 1512 for increased strength and to serve as an abutment for the ends of the blades. The casing upon which the centralizersin the different figures are mounted isnumbered 22.

Inthe .twomodifiedrconstructions shown in Figs. 11, 12, 1'3 and 114, respectively, the end sections of the bands adjacent thecollars are modified by narrowing the width of the bands or piercing slotted apertures therein. Referring first to .the construction shown in Figs. 11 and 12, collars 23 are formed of strips of metal with diameters large enough .to slidably fit the-exterior of the casing upon which the tool is to be mounted. The collars .in this construction are simply cylindrical sleeves. The bands or blades extending between the collars designated by numerals 24 are bowed outwardly as in the previous construction to contact the wall of the well and the extremities of the bandsare Welded, riveted or otherwise fixedly attached to the exterior surface of the collar. The midsections of theseout-bowed blades are widest along the section of the blades which contacts the well wall tapering to anarrower width 24a adjacent the upper andlower collars; thus, the bands or blades 24 have a relatively narrow width adjacent the collars and a wider width at their midsections. Like the centralizer shown in Figs. 1 and 2, the tool is usually mounted on the casing 22 by sliding the .collars onto the exterior of the casing and thereafter welding a fixed collar 25 or abutments in the formof stops onto the exterior of the casing between the upper and lower collars. When the casing is being run into the welloron .the downward stroke during reciprocation, the fixed collar pulls the centralizers with it by abutment with the lower collar'and on upward movement of the casing, the fixed collars pull the centralizers by abutment with the upper collars.

Thesecond modification of the centralizer construction 3 bands in the collars.

is shown in Figs. 13 and 14. Here the upper and lower collars 23 are again made from plain strips of metal as in the centralizershownin Figs. 11 and 12. The out-bowed bands 26 in this modification are slotted longitudinally above and below their midsection as indicated at 26a which slots form apertures .for the passage of fluid flowing axially in the annular passageway surrounding the-casing. The reduction of the width of the bands as indicated :in the vcentralizer shown-:in.Figs. 11 and Band the slotting of the bands, as indicated in the modification shown in Figs. 13 and 14, increases the circumferential width of the passageways afforded .the =fiuids and reduces the size of the obstructions, thereby increasing the freedom of flow of fluids through the well bore outside of the casing.

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Thus, it will be seen that there has been provided cenralizer con truct o s w ic permit less hindrance to the flow of fluids, such as mud and cement slurries, around the casing, thereby avoiding to a great extent the difficulties experienced with the caking of the mud and the setting of the cement in the vicinity of the well tools.

As many possible embodiments may be made of the invention Without departing from the scope thereof, it is to be understood that all matterherein set forth or shown in the drawings is to be-ititerpreted as illustrative and not in a limiting sense.

From the foregoing it will be seen that this invention is one well adapted-to attain all of theends andobjects hereinabove set forth together with other advantages which are obvious and which are inherent to the structure.

it will be understood that certain features and subcombinations are of utility and may be employed without reference to other features and subcombinations. This is contemplated by andis within the scope of the claims.

Having thus described myinvention I claim:

I. A centralizer adapted to be-rnounted on casing used in, wells for the production of fluids, comprising upper and lower collars whose inside diameters are enough larger than the casing to :lit slidably thereon, narrow out-bowed bands extending between the collars with their upper ends attached to the upper collar and their lowerends to the lower collar, an annular boss around the mid-section of the collars and spaced-apart perforations through said bosses, the out-bowed ibands split longitudinally at their ends and said split ends inserted into and rigidly anchored intheperforations of the'collars.

2. A centralizer-adapted to be mounted on casing used in wells for the production of fluids, comprising upper and lower collars whose inside diameters are enough larger than the casing .to fit slidably thereon, narrow out-bowed bands extending between the collars with their upper ends attached .tothe upper collar and their lower ends to the lower collar, an annular boss formed in the midsections of the collars, spaced apart perforations formed in said collar bosses, tabs positioned relative said perforations, the out-bowed bands split longitudinally at their ends and notches formed in the sides of said split ends whereby insertion of the ends of the bands through said perforations in the collar bosses etfects engagement of the tabs in the notches and rigid anchoring of the ends of the References Citedin the file of this patent UNITED STATES PATENTS

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