US2197396A - Oil well cementing plug - Google Patents

Description

' April 16, 1940.,

t F. MAINES 2,197,396

OIL WELL CEMENTING PLUG I Filed Dec. 29, 1957 Q Patented Apia 16, 1940 UNITED STATES PATEN OFFICE;

. on. WELL CEMENTING m. Fred Maines, Long Beach, Calif;

Application December 29, 1937, Serial No. 182,195

Claims.

10 and to provide a construction that will be effective in producing improved and beneficial resuits in the cementing operations, particularly the keeping of the cement and fiuidentirely separate from each other while the cement is being 1' forced downwardly through-the casing, and until such time as it is discharged from the lower end of the casing into the well hole, and further, to provide the lower one of the plugs which has a passageway to permit the cement to discharge downwardly through the plug, with a barrier that normally prevents the flow of cement downward ly through the plug, but which barrier may be ruptured or broken under a predetermined degree of pressure applied to the cement by the pump 25 at the top of the well while the bottom plug rests on the float-shoe or other obstruction at the lower end of the casing.

A further object of my invention is to provide well cementing plugs of the character referred to that will'cooperate so as to enable the cement to be conveniently and economically delivered through the casing to the point where the cementing of the well is to be accomplished, and the cement then being forced under pressure through the lower one of the plugs and the float-shoe that is carried by the lower end of the casing into the annular space within the well hole around the casing so as to provide a concrete wall surrounding the well hole throughout the area throughwhich water flow or seepage would otherwise occur.

With the foregoing and other objects in view, my invention consists in certain novel features a of construction and arrangements oi parts that will be hereinafter more fully described and claimed and illustrated in the accompanying drawing in which:

Fig. 1 is a vertical section taken through the 50 lower portion of a well hole, with the casing positioned therein and showing nrv improved cementing plugs positioned within said casing and with the lower plug resting on the float-shoe that is carried by the lower end of the casing.

Fig. 2 is a side elevational view partk in section, oi! a modified form of the upper one of the plugs.

Fig. 3 is a detail section taken through the upper portion of a modified form of the lower plug.

Fig. 4 is a vertical section taken through the 5 lower portion of a modified form of the'upper plug and also the upper portion of a modified form of the lower plug.

Referring by numerals to the accompanying drawing which illustrates a.preferred embodil0 ment of my invention, It designates the well casing that occupies the well holel W, the lower end of the casing being detachably connected to a conventional float-shoe S provided with the usual axial opening 0.,

The lower plug, designated by the numeral II,

is substantially cylindrical in form and con-- structed of. wood, metal, rubber or composition.

The diameter of this plug is slightly less than the internal diameter of the well casing, and the length of the plug issomewhat greater than its diameter. The lowerend of the plug I l is slightly tapered, as designated by I2, in order to permit the marginal portion of the packing disc,

- carried by the lower end of the plug to flex up wardiy as a result of contact with the wall of the casing as the plug passes downwardly there' through, and extending axially through the plug .is a bore or opening 13.

Secured in any suitable manner to the under face of the plug l I is a packing disc I! preferably formed of flexible or semi-flexible material, for instance leather or composition, and the edges of this discare adapted to engage the inner face of the casing as the plug moves downwardly therethrough.

Formed in the center of this packing disc is an aperture I! that coincides withthe axial bore or opening it through plug ll.

' Overlying the upper end of plug II is a section or sections it of thin material, preferably heavy fabric such as canvas, or thismember may be leather, composition, or in some instances thin sheet metal such as tin, aluminum, copper or the like. I Instead of utilizing a barrier of fabric, leather, sheet metal or the like, the barrier may take the form of a valve having means associated with it to normally maintain it in closed Position, and

which will open only under a predetermined degree of pressure.

Overlying this member I6 is a packing disc I! that is practically identical with the disc I, and

being formed of flexible or semi-flexible material L such as leather or composition, and the edge of this disc engages the inner face of the casing as the lower plug moves downwardly there- -through.,

Formed in the center of packing disc I! is an I aperture 18 that coincides with the axial bore ii in plug I l. Suitably secured camp of the packing disc I! is a disc Is that is somewhat smaller in diameter than the packing I], said disc is being preferably formed of wood, metal com- 10 position or the like, and having formed through its center an aperture II that coincides with the -aperture iii in packing member l1 and the bore l3throughplug ll.

The upper plug, designated by numeral 2|, com- 1s prises a solid cylindrical body preferably formed Applied to the under face ofthe lower one of the packing members 23 and concentric therewith is a ring 24 of wood, metal, composition or so the like, and which is securely fastened to the lower end of the plug.

Suitably secured to the upper end of plug 'II and overlying the intermediate portion of the upper packing member 23 is a concentrically ar- 35 ranged disc 25 that is slightly smaller in diameter than said upper packingmember, and thus only the marginal portion of the upper packing member functions to close and pack the joint between. the upper end of the plug and the inner face of a the casing.

In Fig. 2 I have illustratedakmodifled form of upper plug 2|, and in such construction the rin 24 at the bottom of the plug and the disc 25 at the upper end thereof are eliminated and the 4s packing members 23 are secured to the end faces of the plug by fastening devices such as nails, screws or the like. In the modified'construction illustrated in Fig. 3, the perforated disc 20 is eliminated and the so flexible member i1 is secured directly to the upper end of the plug H by nails, screws or the like, and said disc overlying the member It.

In the modified construction illustrated in Pig. 4, the disc l9 that is applied to the upper end of 55 the lower plug l I is provided with a centrally arranged tapered aperture 2 6 that functions as a seat for a tapered plug 21; which'latter projects from the lower end of the upper plug 2|.

In the use of my improved cementing plugs,

go plug H is placed in the upper end of the casing and cement is pumped into the casing on top of said plug, with the result that the plug and cement are forced downwardly through the casing and all mud and liquid in front of or below as the plug will be forced downwardly through the swing and discharge through the lower end thereof through opening 0 in float-shoe B. This mud and liquid will be forced upwardly through the annular space surrounding the lower 70 portion of the casing. After the required amoimt of cement has been delivered into the casing, the upper plug 2! is placed in the casing on top of the cement and mud or liquid is now pumped into the casing above the upper plug 2i, thus forcing an the two plugs with the interposed body of cement aromas downwardLv through the casing until the lower end of the lower plug rests on the float-shoe or other obstruction.

During this downward movement of the plugs and cement, the packing members M and i1 5,

scrape the inner surface of the casing thereby removing practically all mudthat might otherwise adhere thereto, and the packing members 28 carried by the upper plug scrape the inner surface of the casing to remove any cement that 10 might adhere thereto.

During the downward travel of the plugs and interposed body of cement through the casing, the member I. functions as a barrier to eifectlvely prevent the cement between the plugs from is do wardly through the, lower plug and mixing wi the mud and liquid below said lower Plug.

when the lower plug ll rests upon the floatshoe or other obstruction, such condition will be indicated on the pressure gauge of the pump and the operation of the pump is continued to build up pressure in the mud or fluid in the casing above the upper plug: and when a predetermined degree of pressure has been delivered that portion 1 oi the member I! that closes the upper end ofopenlng il in the lower plug will be ruptured, thereby bringing about a drop in the pressure which condition will show on the pressure gauge associated with the pump and thusthe pump 0 operator will know that the member It has been ruptured so as to permit the cement to pass downwardly through-the opening in the'floatshoe.

Continued operation of the pump develops sufflcient pressure to expel said cement through the opening it in the lower plug and through'the opening in the float-shoe. and this cement will be forced upwardly through the annular space surroimdlng the casing, and which action elevates 40 the mud and liquid previously'expelled from the lower portion of the casing and thus provides a cement wall around the casing that keeps water from seeping into the protected'portion of the well hole. A

As the cement is forced upwardly in the well hole around the'casing and drives the mud or fluid upwardly, a practically definite separation of the cement, mud and fluid is produced and maintained, due to the difference in the specific I0 gravities of the mud or fluid and the cement, the latter being considerably heavier than the mud or fluid. n

An especial advantage of my improved cementing plugs is that the member Ii that is carried by II the lower plug forms a barrier that keeps the cement pumped into the casing, entirely separate from the mud or water below the plug and within the well hole "surrounding the casing. 1

Obviously, the barrier member it may be iormedof any material that will rupture under a predetermined degree of pressure and as a result, the plugs may be used under any and all condi- 'tions regardless of the depth at which the cementing-off job is accomplished, and likewise regard- 9s less of the amount of cement required for accomplishins the desired results.

As a valve is used in the place of the barrier Ii, said valve may be of the type that is normally held in closed position by a. spring, and which (0 latter is of such size and tension as to yield only under a predetermined pressure. a

when all of the cement has been expelled. through the lower plug, the lower end of the upper plugor the ring 24 carried thereby will rest 1;

directly on top of the lower plug or the disc I9 carried thereby, thus providing a fluid-pressure tight joint between the two plugs and the joints between the ends of both plugs and the casing are sealed by the packing members I4, l1 and 23 that are carried by the ends of the plugs.

Where the modified construction illustrated in Fig. 4 is provided, the tapered member 2'! that effective in performing the functions for which it is intended.

It will be understood that minor changes in the size, form and construction of the various parts i of my improved oil well cementing plugs may be made and substituted for those herein shown and described without departing from the spirit of my invention, the scope of which is set forth in the appended claims. i

I claim as my invention: 1. A well cementing plug provided with a pas- I sageway for mud, fluid and cement, a member normally closingsaid passageway and adapted to rupture under predetermined degrees of pressure, and a packing disc carried by said plug.

2. A well cementing plug provided with a passageway for mud, fluid and cement, a member normally closing said passageway and adapted to rupture under predetermined degrees of pressure and packing discs carried by the ends of said plug.

3. In an oil well cementing means, the combination witha cementing plug and packing members carried by the ends thereof of a second plug provided with an axial opening, a rupturable' member closing said opening and packing members carried by the ends of said second mentioned p ug.

4. An oil well cementing pl having an axial opening, packing members carried by the ends plug having a passageway for-mud, liquid and cement, a rupturable member closing saidpassage'way and capable of being ruptured under predetermined degrees of pressure, a plate secured to the plug and overlying said member, said plate having an aperture that coincides with'the passageway'in the plug and a member projecting from one end thereof and adapted to'enter and close the aperture in the plate that'is carried b the first mentioned plug.

6. A cementing plug provided with an axial duct for the passage of mud, liquid and cement, means normally closing said duct and adapted to rupture under a predetermined degree of pressure and a member overlying said duct-closing means and provided with an aperture that registers with the duct through said plug.

'7. A cementing plug provided with an. axial duct for the passage of mud, liquid and cement, means secured to one end of said plug for nor mally closing said duct and adapted to rupture under a predetermined degree of pressure and means carried by said plug for packing the joint between said plug and the casing in which said plug is positioned;

8. The combination with a cementing plug having aduct for the passage of mud, liquid and cement and means normally closing said duct and adapted to rupture under a predetermined degree of pressure, of a second plug adapted to be positioned'in the well casing above the first-mentioned plug.

9. The combination with a cementing plug having a duct for the passage of mud, liquid and cement and means normally closingsaid duct and adapted to open under a predetermined degree of pressure,.of a second plug adapted to be vpositionedlin a well casing above the first-mentioned plug and means for packing the joints between said plugs and the casing in which they are positioned.-

10. The combination with a cementing plug having a duct for the passage of mud, liquid and cement and means normally closing said duct and adapted to open under a predetermined degree of pressure, of a second plug adapted to be positioned in a well casing abovethe first-mentioned plug, means for packing the joints between said plugs and the casing in which they are positioned and means for producing a fluid pressure tight joint between the upper end of the lower plug andthe lower end of the upper plug.

FRED MAINES.

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