US2515149A - Double bow reverse spiral centralizer - Google Patents

Description

July 11, 1950 WILLHOIT 2,515,149.

DOUBLE BOW REVERSE SPIRAL CENTRALIZER Filed March 16, 1948 g] INVENTOR.

fifac%fi%7fiazlj ATTCI RN EYS Patented July 1 1;, 1950' DOUBLEBOW REVERSE SPIRAL CENTRALIZER Jack'G. Willhoit, Lafayette, La., assignort Willhoit Tool- Co. Inc., Lafayette,.La., a corporation ApplicationMarch 16, 1943; Serial N0. 15,223

'-This invention relates to well casings as used in oil and gas wells wherein outwardly bowed flat, spirally disposed spring strips with the ends incun-ted through collars on thewell' casing are "provided for centralizing the casing and cleanin the hole to prevent thecasingfrom sticking, and in particular the invention relates to a centhe torque so that the casing will not be unscrewed and which will clean excess mud cake from. the face of the formation and permit the cement to bond with the formation.

Various types of centralizing devices have been provided for well casings which'remove excess mud cake and other matter from the wall of the formation and hold the casing substantially in the center of the hole, and some of these use outwardly bowed spring steel strips, but in these devices the strips are either straight or wind in the same direction and this causes the sections of the well casing to unscrew and stick in the formation. With this thought in mind this invention contemplates a well casing centralizer that acts as a trowel to smooth down the well bore and that does not impart torque of the casing during the raising or lowering thereof.

The object of this invention is, therefore, to provide a centralizer for well casings that is so constructed that the torque is neutralized and that removes all growth and mud cake from the wall of the well so, that the cement forms an effective bond with the formation.

Another object of the invention is to provide a well casing centralizer that eliminates pressure differential between the drilling mud column and wall of the bore thereby preventing sticking of the casing.

A further object of the invention is to provide an improved well easing centralizing device that equalizes lateral forces, eliminates torque, and removes growth, mud cake, and the like from the wall of the bore of the well which is of a simple and economical construction.

With these and other objects and advantages in view the invention consists of the new and novel combination, construction, and arrange 3' Claims. (Cl.'1664) mentof parts as hereinafter more fully described, set forth in the claims appended hereto, and disclosed in the accompanying. drawing forming part hereof, wherein:

Figure 1 is a View showing a side elevation of the centralizer.

Figure 2 is a similar view with parts broken away illustrating the device on a well casing and positioned in a well bore. Figure 3 is a plan view'looking downward upon the upper end of the centralizer.

Figure 4 is a sectional plan taken on line 4:-4 of- Figure 1, showing a section. through the intermediate collar betweenthe two sections of the device; I

Figure 5 is a similar sectional plan throug the-device taken on line 5- -5' of Figure 2 showing the lower collar and stationary lugs'on the well casing."

Figure: 6 is a similar section on an. enlarged scale takenon linev 6-45 of Figure 2, illustrating the outwardly bowedspring strips.

Referring now to thedrawings wherein like reference characters denote corresponding parts the well casing centralizing device of this invention includes an upper collar Ill, a lower collar H, an intermediate collar 12, an upper set of outwardly bowed spring strips IS, a lower set of similar, but oppositely winding spring strips I4, upper stationary lugs l 5, and lower stationary lugs H5.

The complete unit including the upper and lower sections is positioned on a well casing ll in a bore l8 with the upper collar l 0 spaced above the upper stationary lugs l5, and the lower collar ll spaced below the lower stationary lugs IS. The unit is, therefore, in substantially a floating position and as the casing is drawn upward the collar Ill will be engaged by the lugs l5 wherein the unit will travel with the casing, and as the casing is moved downward the lugs It will engage the lower collar II and draw the unit downward.

The strips l3 and M are formed of fiat spring steel, or the like and the ends of the strips [3 are welded to the collars ill and I2 while the ends of the strips [4 are welded to the collars I2 and H. The lower ends of the strips l3 are attached to the upper part of the collar [2 at the points I 9 and the strips are spirally positioned, winding in a clockwise direction with the upper ends attached to the collar ID at the points 20. The lower ends of the strips M are attached to the lower collar I l at the points 2| and the strips wind upward in a counter-clockwise direction with the upper ends attached to the intermediate collar l2 at the points 22. The intermediate sections of the strips of both parts of the unit are bowed flat outwardly, as shown.

The lugs l5 and I6 are welded directly to the well casing and these are positioned to locate the units in spaced relation along the well casing.

With the outwardly bowed spring strips mounted on a well casing in this manner lateral thrusts or forces will be equalized, being absorbed by the spring strips, and the casing will be centralized in the bore. Winding the strips in opposite directions neutralizes the torque and thereby prevents unscrewing of the sections of the casing while the casing is being raised or lowered. And positioning the spring strips in this manner cleans excess mud cake and growth from the face of the formation and permits a more effective cement bond with the walls of the formation.

It will be understood that modifications may' be made in the design and arrangement of the parts without departing from the spirit of the invention.

What is claimed is:

1. A centralizer for well casings comprising an upper collar, a lower collar, and an intermediate collar slidably mounted on a well casing, a plurality of spirally positioned spring strips with the upper ends thereof attached to the upper collar and the lower ends thereof attached to the intermediate collar, a plurality of spirally positioned spring strips with the upper ends thereof attached to the intermediate collar and the lower ends attached to the said lower collar, one set of said spring strips extending in a clockwise direction and the other in a'counter-clockwise direction, and both sets of said spring strips bowed outwardly at points intermediate of the ends thereof, lugs on the well casing spaced from the lower edge of said upper collar, and additional lugs on the well casing spaced from the upper edge of said lower collar.

2. A centralizer for well casings comprising anupper collar, a lower collar, and an intermediate collar, a plurality of spirally positioned spring strips winding clockwise with the upper ends thereof attached to the said upper collar and the lower ends thereof attached to the intermediate collar, a plurality of spirally positioned spring strips winding counter-clockwise with the upper ends thereof attached to the intermediate collar and the lower ends thereof attached to the lower collar, said collars slidably mounted on a well casing, lugs on the said well casing spaced from the lower edge of the said upper collar, and lugs on the well casing spaced from the upper edge of the said lower collar.

3. A centralizer for well casings comprising an upper collar, a, lower collar, and an intermediate collar, a plurality of spirally positioned spring strips winding clockwise with the upper ends thereof attached to the said upper collar and the lower ends thereof attached to the intermediate collar, a plurality of spirally positioned spring strips winding counter-clockwise with the upper ends thereof attached to the intermediate collar and the lower ends thereof attached to the lower collar, said collars slidably mounted on a well casing, lugs on the said well casing spaced from the lower edge of the said upper collar, and lugs on the well casing spaced from the upper edge of the said lower collar, and both sets of said spring strips bowed flat outwardly at points intermediate of the ends thereof.

JACK G. WILLHOI REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Hall Nov. 5, 1940

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