US2572533A - Expansible plug for cementing wells - Google Patents

Description

Oct. 23, 1951 H. R. STEWARD 2,572,533

EXPANSIBLE PLUG FOR CEMENTING WELLS Filed Feb. 4, 1949 INVEN H. 2; 8751114 14 08 A/EYS.

Patented Oct. 23, 1951 UNITED STATES PTENT OFFICE 3 Claims.

This invention relates to apparatus for cementing wells, and more particularly to an expansible plug which can be positioned in a well to temporarily seal off a lower portion of the well while cement is being applied to a portion of the well immediately above the plug.

It is among the objects of the invention to provide a collapsible plug which may be lowered through a well casing or lining to a desired position below the bottom end of the casing and there expanded into sealing engagement with the wall of the well to hold cement pumped into the well and prevent such cement from passing below the plug to a location where it might interfere with the flow of valuable material into the well, which plug is firmly supported at the desired level and is automatically expanded into sealing engagement with the wall of the well, is simple and economical in construction andreadily destructible by a drill bit so that the well can be quickly and easily re-opened after the cementing operation is completed, and so that the use of the expansible plug does not add materially to the cost of cementing a well, which plug is easily variable for different well sizes and different conditions of the walls of difierent wells, and may be used with conventional well-drilling and cementing equipment.

Other objects and advantages will become apparent from a consideration of the following description and the appended claims in conjunction with the accompanying drawing, wherein:

Figure 1 is a somewhat diagrammatic, longitudinal cross-section of the lower portion of a well showing a well casing therein and an expansible plug illustrative of the invention positioned in the well below the bottom end of the casing, a bottom portion of the casing and a portion of the plug being broken away and shown in crosssection to better illustrate the construction of the plug and the cooperation thereof with the well and well casing;

Figure 2 is a top plan view of the plug in expanded condition; and

Figure 3 is a transverse cross-section of a well casing showing therein a top plan view of the expansible plug in collapsed condition for passing through the casing.

With continued reference to the drawing, the

well hole is illustrated as having a somewhat irregular wall II] extending outwardly into basins II somewhat above the bottom I2 of the well, which basins are located at the level of valuable material, such as oil, gas, brine or water, which it is desired to remove through the well. The

well lining or casing I3 is somewhat smaller in diameter than the well bore and terminates above the basins II from which the valuable material flows into the well. A screw-threaded union fitting I4 may be secured on the bottom end of the casing, if desired.

The expansible plug is generally indicated at I5, and comprises an elongated post or column I6, the bottom end of which rests upon the bottom of the well when the plug is in operative position, and the upper end of which is positioned between the basins I I at the level of the valuable material and the bottom end of the well casing I3 and near the bottom end of the well casing. The length of the post I6 is predetermined'by drilling measurements of the well and the post is cut to the proper length before the expansible plug is lowered to the bottom of the well through the well casing. A polygonal plate I I substantially concentric with the post I6 and perpendicular to the longitudinal center-line of the post is provided on the upper end of the post either permanently attached to or formed integrally with the latter. The edges of the polygonal plate I! are provided with respective pairs of spacedapart hinge eyes or loops I8, and a number of wing plates I9 equal to the number of straight edges of the polygonal plate I! are secured respectively to the straight edges of the polygonal plate for movement inwardly and outwardly about such pivotal or hinged connections.

Each of the wing plates I9 is trapezoidal in form and has on its shortest edge a hinge loop--20 disposed between the hinge loops I8 on the corresponding edge of the polygonal plate I? to receive a hinge pin extending through the cooperating hinge loops. Each wing plate I9 preferably has beveled side edges and may be curved or dished near its outer end to somewhat more closely conform to the cylindrical shape of the well bore.

In placing the expansible plug in operating position at the bottom of the well casing, as illustrated in Figure 1, the wing plates are swung inwardly to their collapsed condition, as illustrated at I3, and the plug is placed in the top of the well casing. It is then allowed to drop through the well casing or may be forced downwardly through the casing by the application of suitable weight, such as a string of drill stem sections, if necessary.

A pair of elongated, curved leaf springs 2| is secured at adjacent ends to the polygonal plate II, substantially at the center of the latter, by a suitable clip 22, and bears against some of the wing plates, for example, the three wing plates constituting the inner triangle illustrated in Figure 3, to resiliently force the wing plates outwardly to their expanded position as soon as these plates drop below the bottom end of the well casing. The spring forces the wing plates outwardly until their outer edges contact the wall of the well bore, so that these plates make a seal a with the well bore immediately below the botupon the shape ofithe polygonal. plate "(,andmay 'be provided in sets of different lengthsto accommodatethe plug'to wells of different sizes or .to varying conditions of the walls ofdifierent well "bores, so that a firm seal can be, providedimmediately belowthe bottom end .ofthe wellcasing regardless of .the sizeof the wellor the condition of its walls.

'After-. the cementing .of the well .haslbeen con ;p1eted,.the plug .may..be..destroy.ed.by actionof a lidr'illrbit lthereon, andaforthis purpose the material of .the plug should be considerably softer than the material. of which drill bits areiconventionally made.

.The'invention may be embodied in other. spe- 'cificfo'rms" without'departing'from the spirit or "essential characteristics thereof. 'embo'dimentis, therefore, tobe considered in all The present respects as "illustrative andnotrestrictive, the scope of "the invention being indicated by the appended claims rather than by the foregoing descriritiongandall changes which come within "the meaning -and range (if-equivalency of the claims-are;therefore, intended to be-embraced therein.

' What is claimed is: 51 A -we'll cementing expan'sible plug c'omprising an elongated post having-on-oneend a plate-of polygonal iormation, and a plurali-ty of wing "plates of substantially trapezoidal formatiorrea'ch hinged' along'its shortest edge :to a respective edge ofsaidpolygonal plate so that said wing plates 'can swing inwardly and outwardly between a collapsed and an expanded condition of said plug, and curved, leaf springs mounted on said polygonal plate and bearing against some of said wing plates to resiliently urge said wing plates out- 5 wardly about their hinge connections with said polygonal plate.

2. A Well cementing expansible plug comprising a post of predetermined length to rest upon the bottom of a well and position its upper end at a desired level for cementing the twell,--'a polygonal plate on the upper end of-said post sulostantially concentric with the latter, a number of trapeuzoidal wing plates equal to the number of straight edges-of said-polygonal plate, a hinge connection 5' between each straight edge of said polygonal :platearid the shortest edge of the corresponding wing plate, said wing plates being movable about said hinge connections between a collapsed condition'in which said plug will pass through a well 20 casing and an expanded condition in which the outen edges. of said .wingplates will contact-the wallof. a well .bore' below. the associatedwell casing, and :spring .means carried onsaid. polygonal gplate and bearing against said wing plates to .resilieritly urgesaid wing plates outwardly -toexpanded condition.

..3. .A well cementingexpansibleplug comprising -.a. post of predetermined length to rest upon the bottomofa well and-position its-upper. endata-de- 3o =siredi level for cementing the .well,: a plurality --.of

trapezoidal wing plates, hingeaconnectionsarespectively. connected-between the. shortest edges .ofsaid wing platesv and .thetopof said post, said wing plates being .movableabout said hingecon- .nections between. acollapsed condition line-which .said plug will pass-through a-well casingandan expanded. condition inwhich :the outer. edges. of -said wing plates .will -contact the wall .of a :well bore below the associated well casin sandr spring means carried on the top: of-rsaid post -within-.-said wing. platesand bearing against said wing'plates to resiliently urge said wing-plates outwardly to expanded condition.

R. -STEWARD.

"REFERENCES .CITED The following references are: of recordcin' the file of this patent:

' UNITED STATES PATENTS Number 'Name Date 1,647,630 ...Hyer. Nov.: 1, 1927 2,117,538 .Baker May .17, 11938

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