US3550683A - Well-cementing apparatus - Google Patents

Description

United States Patent Inventor Bobby G. Comeaux Marrero, La.

Appl. No. 857.305

Filed Sept. 12, 1969 Patented Dec. 29, 1970 Assignee The Dow Chemical Company Midland, Mich.

a corporation of Delaware WELL-CEMENTING APPARATUS 2,655,216 10/1953 Baker et a1 166/156 3,102,595 9/1963 Fisher. Jr et al. 166/156 3,159,219 12/1964 Scott 166/156 Primary Examiner-James A. Leppink Attorney-Griswold and Burdick ABSTRACT: In the course of cementing well casing in place in a bore hole, a plug follows the cement down the casing and sets against a sealing surface in the casing, such as a cementing 5 Claims 4 Drawing shoe in the casing. When drilling out the plug and the sealing U.S. fa e after the ement has et [he often rotates lllt- Cl E21b33/16 the rotating drill bit, making difficulty for the bit to bite into Field of Search 166/15 the rubber plug.

291 This invention provides slots in the sealing surface which R r d mate with protuberances on the surface of the plug which face e erences e the sealing surface, whereby as the plug seats and is rotated UN STATES PATENTS slightly, the protuberances lock in the slots and prevent 2,071,390 2/1937 Crowell 166/155 further rotation ofthe plug.

54 3 I l; I 2 2 5 42 56 Z4- e s Z0 I I 1'0 52 a PATENTEU 050291910 3550.683

INVENTOR. Boy 6 Comeoux WELL-CEMENTING APPARATUS BACKGROUND OF THE INVENTION This invention relates to well cementing apparatus, and particularly to cementing plugs and the shoes, float collars and stage or fill collars in which the cementing plugs are seated.

When casing is cemented into a well, a latch down plug is injected into the casing immediately following the cement slurry. The plug is followed by drilling mud which is pumped into the casing to force the cement and the plug down the casing. When the plug reaches the stage collar, float collar or cementing shoe equipment, the latching apparatus enters an aperture in the equipment and locks the plug in place. The plug, therefore, has acted as aseparator and wiper as it traverses the easing behind the cement and finally acts as a valve to shut off the orifice in the collar or shoe and prevent return of the cement slurry back up the casing.

When the cement has set it is often desirable to drill through the collar or shoe to deepen or otherwise modify the bore hole. When the conventional plug and collar or shoe are used, difficulty is encountered in drilling out the plug because the drill bit does not bite into the rubber because the. rubber plug rotates with the drill bit.

Accordingly, a principal object of this invention is to provide an improved cementing plug and collar or shoe seating apparatus.

Another object of this invention is to provide an improved cementing plug and seating apparatus in which the plug is nonrotatable when in place within the seating apparatus.

In accordance with this invention well cementing equipment comprising a cementing plug and seating apparatus are provided wherein slots or grooves are made in the upper face of the seating apparatus. Mating protuberances or teeth are coupled to the bottom of the wiper plug to lock into the grooves or slots of the seating apparatus, thus preventing rotation of the plug.

The invention, as well as additional objects and advantages thereof, will best be understood when the following detailed description is read in connection with the accompanying drawing in which:

FIG. 1 is a side elevational view, partly broken away and in section, of seating apparatus in accordance with this invention, as applicable for use in a cementing shoe;

FIG. 2 is a sectional view taken along the line 2--2 of FIG.

FIG. 3 is a side elevational view of a cementing plug in accordance with this invention; and

FIG. 4 is an inverted plan view of the cementing plug shown in FIG. 3.

Referring to the drawing, and particularly to FIGS. 1 and 2, there is shown a cementing shoe, indicated generally by the numeral 10, comprising a hollow cylindrically shaped outer wall part 12 having threads 22 on the inner wall of the upper part of the shoe 110, a lower part 13 and a plate 16 extending transversely across the shoe between the upper and lower parts. The plate 16 divides the shoe into two compartments and has a central bore whose wall part 46 is a seat for the lower end part 62 of the plug 48 shown in FIG.3.

A cement plug receiving body part, indicated generally by the numeral 20, is generally frustoconical in shape on its outer surface, the wall adjacent to the base having threads which engage the threads 22. The body part 20 lies against the partition 16 and has a central bore 32 aligned with and slightly larger in diameter than the bore in the partition 16.

A frustoconically shaped counter bored part 28 forms a seat for the lower end part 50 of the plug 48 shown in FIG. 3 and extends from the top 26 of the body part 20 to the grooved upper end part 30 of the bore 32.

An array of arcuate slots 34,36,38, having the same radius of curvature, for example, and sloping in depth, is disposed in the body part 20 extending inwardly from the surface 28 and usually symmetrically surroundin the bore 32. A slot 40,42,44 extends from each of the sIots 34,36,158 respectively. to the bore 32.

The above described shoe 10 is coupled to a length of casing 14 with the inner wall 24 of the casing fitting between the body part 20 and the outer wall part 12 of the shoe l0. A cementing plug, shown in FIGS. 3 and 4, and indicated generally by the numeral 48, has a flared upper end 68, a more or less semicircular lower end 62, an array of flexible wiper fins 66 a frustoconical seating surface 50 adapted to mate with the surface 28, a downwardly extending shaft 58 having latching grooves 60 disposed between its ends, and O-ring seal elements disposed adjacent to the lower end 62 and adapted to bear against the unthreaded part of the wall of the bore 32. Embedded in and bonded to the frustoconical surface part of 50 of the plug 48 are an array of 3 arcuate shaped strips 52,54,56 which extend downwardly from the surface 50 in longitudinal alignment with the slots 34,36,38. The length of the arcuate strips is less than the length of the slots 34,36,38, and the arcuate strips are adapted to mate with the slots 34,36,38.

In operation, the plug 48 is dispatched down the bore hole through the casing 14 following the cement. The plug 48 is followed by usually mud or other pumpable fluid material.

When the plug 48 reaches the counter bored part 28, the strips or teeth 52,54,56 settle into the grooves or slots 34,36,38, the lower end of the 62 of the plug passing into the bore 32 and seating on surface 46 as the grooves 60, 30 latch together.

After the cement has set and the plug is to be drilled out, the bit (not shown), in tending to rotate the plug, drives the teeth even deeper into the grooves 34,36,38, with material in the grooves being forced out through the slots 40,42 ,44.

Thus, even though the bit rotates against the rubberlike top of the plug 48, the plug cannot rotate and the bit drills through the plug and then on through the seating apparatus.

The teeth 52,54,56 are usually made of metal, such as aluminum, for example, which is embedded in and bonded to the rubberlike material used in making the rest of the plug 48.

I claim:

I. Well-cementing equipment comprising a seating apparatus adapted to be coupled in a length of easing, said apparatus having a body part including a partially grooved axially disposed bore and a frustoconically shaped counterbore part on the end thereof facing the upper end of the casing, said frustoconically shaped part having an array of arcuate slots disposed generally around said axially disposed bore, and a plug member having a frustoconical surface adapted to mate with said frustoconically shaped part of said apparatus, said frustoconical surface having an array of arcuate teeth extending downwardly therefrom in axial alignment with said arcuate slots and adapted to mate with said slots.

2. Well-cementing apparatus in accordance with claim 1, wherein a latching and sealing section extends below the frustoconical surface of said plug.

3. Well-cementing apparatus in accordance with claim 1, wherein said arcuate slots are of greater depth at one end than at the other.

4. Well-cementing apparatus in accordance with claim 1, wherein slots extend between each of said arcuate slots and said axially disposed bore.

5. Well-cementing apparatus in accordance with claim I, wherein said teeth are made of metal embedded in and physically coupled to a flexible material.

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