US1851289A - Oil well cementing plug - Google Patents

Description

March 29, 1932. J. M. OWEN OIL wELL CEMENTING PLUG Filed`Dec. l, 1928 I N VE Y TOR M @werf .l a .1 c f a. A.

A TTORNEYL Patented Man 29, 1932 i T oFFlCE i JACK E. om, CF LONG BEACH, CALIFORNIA OIL 'WELL CEMENTING PLUG Application led December 1, 1938. SeriaI' No. 323,105..

'.llhis invention relates to a plug used in oil well cementingY as anindicator. In oil well cementing, the well casing is commonly sealed off from the well hole side wall by introducing cement into the casing and forcing it downwardly around the bottom and into the space between the casing and hole. It is then maintained in such position until the cement sets. Plugs have been currently used and placed at the top of the introduced column of cement grout travelling therewith and acting as an indicator of the position of the column. This has ybeen accomplished by pumping the column of grout vinto the casing and causing the plug to be arrested in its travel when it reaches the lower end vof the casing and by the arrest of its travel indicating through reaction to the pumpiugpressure,- that it has obtained its position. After the plug has reached its lower position, it is the common practice to closethe upper end of the well casing and maintain the column of grout in position while setting-takes place. Plugs have been employed which pack oii the casing and are free to travel downwardly, but

are restrained against upward movement so that retention of pressure on the top of the plug is not necessary to` hold the column of cement grout in position and it is not necessary to maintain the top of the casing closed. The present invention relates to a plug of the latter type. In such types of plugs, diiiicult has been experienced in maintaining a lea tight packing and preventing the fluid on opposite sides of the plug from passing around the latter.

The objects of this invention are to provide a plug having any yor all of the following features:

A packing which is automatically expanded by pressure of fluid from above; a plug having means to permit only one-way travel, namely, downward and provided with restraining means to prevent' upward travel; l

and packing means arranged to be expanded upon upwardpressure thereon when the plug is in its arrested position and which is main tained in such packing position with an expansive force acting on the packing 1n propor-` tion to the upward pressure exerted thereon.

These objects together with other objects of corresponding accomplishments are obtained by means of the embodiment of my invention illustrated in the accompanying drawings:

Fig. 1 is a conventional view of an oil well hole with a casing therein and my improved plug in its initial arrested position, a portion of the casing being shown in elevation and a portion in section, the plug being shown in elevation; Fig. 2 is a plan view of the plug on an enlarged scale; Fig. 3 is a section as seen on the line 3 3 of F ig.2 with parts in packing non-expanded position; and

Fig. 4 is a fragmentary view in elevation similar to Fig. 3 showing the follower in packing expanded position.

Referring more particularlyV to the drawings, Figs. 1, 2 and 3 show the plug in packing non-expanded position. The well hole is marked 5 and disposed therein is a well casing 6 provided with the usual guide shoe 7 at the bottom thereof. At the bottom, collar 8 and indicator seat 9 are installed, the latter being a ring with port 10 extending therethrough. At the top of a casing is tight head 11 to which a pump line of pipe 12 is connected. A valve 13 is provided for shutting olf pressure, if desired.

The well is cemented in the following manner: Mud is rstintroduced and circulated to wash' out slush. A tight head having a cement plug releasably retainedV in it is placed irliosition on the casing.- Cement lgrout of a s cient quantity is then pumped into the casing. The plug isindicated generally by 14 in Fig. 1. It is released upon the topof the column of cement grout. Mud is next pumped on top of the plug causing it andthe column of cement grout to be forced downwardly throu h the guide shoeand around the casing. hen the plug engages the seat 9, its travel is arrested, and back pressure is developed .which may be sufficient to stall the pump, indicating that the cement has reached its position for setting. With my improved plug, the cement will be'retained in this position, as the plugwill maintain itself against upward movement.` With the usual free movable plug, the valve 13 is closed to trap the liquid in the casing. Obviously a cans/100- rpacked against siderable back pressure is developed tending to move the plugupward.

My improved plug comprises a cylindrical body portion 15, which may be of wood or any other suitable material. Attached to the bottom is a disk of rubber belting or the like 16 acting as a guide and also aiding in maintaining a leak tight t with the casing. Attached to the body 15 at the upper end of the plug is apacking cup 17 having its trailing edge directed upwardly and preferably provided with a tapering outilaring wall. Upstanding from the body are guide osts 18 and slidably mounted thereon is a ollower 19 to which is attached a plate 20. The cup is preferably made of rubber, the follower 19 of wood and the plate 20 may be of iron. Three posts are shown and mounted thereover between the follower and the body are compression springs 21. These springs tend to normally maintain the follower out of contact with the cup or in cup non-expanding position. Ears 22 are provided on the plate and pivotally mounted between each pair of ears is' a dog 23 having a toothed arcuate outer surface 24 which is eccentric to the pivotal axis 25 of the dog. Compression springs 26 are provided tending to maintain the dogs in their outer positions. If the follower is moved downwardly and nested within the cup, it will force the cup outwardly into expanded position. n

The dogs are so arranged that there is a substantially free movement of the plug downwardly until it reaches the seat 9. The outfiaring cup as shown in Fig. 1, initially hugs the casing while the body of the plug is free. Thus, easy downward travel of the plug is permitted and pressure from above immediately expands the cup. Pressure of fiuid from above tends to expand the cup to maintain a tight it with the casing. After the cup has engaged the seat and the pump is stopped, pressure is relieved upon the to of the plu Thereupon, the pressure o the cement rom below tends to move the plug upwardly. The follower is retained against movement due to the dogs engaging the well casing. In this position, the body is enabled to be moved upwardly so that the follower is moved into nested position with respect to the cup and the latter is expanded. The amount of ex ansion will depend upon the pressure from below. The casing is thus the cement from below. The plug is allowed to remain in this position until cement has set, and thereafter the plug and cement within the casing are drilled out.

What I claim is:

1. A cementing plug for oil well casing comprising an elongated plug body, an outaring tapered pac 'ng cup secured to and upstanding from said body at its upper end with its trailing edge directed upwardly, a follower secured to said body at its upper end so as to be longitudinally movable, said i follower being arranged to be nested in said cup to expand the latter and being normally maintained in packing non-expanding position, and one-way gripping dogs secured to said follower to engage the well casing and prevent upward displacement.

2. A cementing plug for oil well casing comprising an elon ated plug body, an outflaring tapered pac ing cup secured to and upstanding from said body at its upper end with its trailing edge' directed upwardly, a follower secured to said body at its upper end so as to be longitudinally movable, said follower being arranged to be nested in said cup to expand the latter and being normally maintained in packing non-expanding position, pivoted gripping dogs secured to said follower to engage the well casing and prevent upward displacement, and spring means acting upon said dogs to hold the latter in contact with said casing.

3. A cementing plug for oil well casing comprising an elongated plug body, an outiaring tapered packing cup secured to and upstanding from said body at its upper end with its trailing edge directed upwardly, a follower secured to said body at its upper end so as to be longitudinally movable, said follower being arranged to be nested in said cup to expand the latter and being normally maintained in packing non-expanding position, and dogs pivotally mounted on said follower having arcuate casing gripping surfaces eccentric to their pivotal axes so as to v provide one-way gripping means and preyvent upward displacement.

4. A cem'entlng plug for oil well casing comprising an elongated plug body, an out- Haring tapered packing cup secured upstanding from said body at its upper end with its trailing edge directed upwardly, a follower secured to said body at its upper end so as to be longitudinally movable, said follower being arranged to be nested in said cup to expand the latter and being normally maintained in packing non-expanding position, dogs pivotally mounted on said follower having arcuate casing gripping surfaces eccentric to their pivotal axes so as to provide oneway gripping means and prevent upward dis placement, and spring means acting upon said dogs to hold the latter in contact with the well casing.

5. A cementing plug for oil well casing comprising an elongated plug body, an outfiaring tapered packing cup secured to and u standing from said body at its upper end with its trailing edge directed upwardly, a follower secured to said body at its upper end so as to be longitudinally movable, resilient means disposed between said body and follower to normally maintain the latter in packing non-expanding osition, do pivotally mounted on said ollower an having to andy l head, said head being` tom of the body, a

nas-mee arcuate casing gripping surfaces eccentric to their pivotal axes so as to provide one-way gripping means and prevent upward displacement, -and spring means acting upon said dogs to hold the latter in contact with the well casing.

6. A cementing plug for oil well casing comprising an elongated body, an outiiaring tapered packing cup secured to and outstanding from the body at the upper end thereof, whereby the lip of said cup will engagethe wall of a casing and pressure from above will cause said cup to hug the casing.

7 A cement plug adapted te be insertedin an oil well, comprising a wooden body substantially the same diameter as the bore of the well, a packing disc secured to the bottom of the bod a packing cup secured to the top of the bo y, a head mounted within thecup above the body, a lurality of posts rising from the body and) extending through the slidably mounted on the posts and a lurality of dogs mounted on the head where y upward movement of said head is prevented.

8. A cement plug adapted to be insert/edili an oil well, comprising a wooden body substantially the same diameter as the bore of the well, a packing disc secured to the botacking cup above the bod a head mounte within the cu above the body, a plurality of posts rising om the body and extending through the head, said head being slidably mounted on the posts and a plurality of dogs mounted on the head whereby upward movement of said head is prevented, a pluralit the head and the pac in cup, said sprin yieldably urging the hea upwardly.

Inwitness that I claim the fone voing I have hereunto subscribed my name t is 20th day of November, 1928. JACK M. OWEN;

of springs between

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