US1860268A - Casing seal for wells - Google Patents

Description

M. G. STEWART CASING SEAL FOR WELLS Filed June 2, 1928 May 24, 1932.

rg L Patented May 24, 1.932

UNITED STATES PATENT OFFICE MARK G. STEWART, OF SHREVEPORT, LOUISIANA, ASSIGNOR TO :PELICAN WELL TOOL AND SUPPLY COMPANY, OE SBIEtEVEPORT,y LOUISIANA, A OOZRIEORA'IION 0F LOUISIANA CASING SEAL FOR WELLS This invention relates to seals for well casings, particularly those used in connection with oil wells, wherein the casing consists of a-plurality of substantially axially aligned 5 sections of progressively decreasing diameters from the ground level downward, and in which it is desirable lto form a seal between the adjacent ends of each pair of sections, to prevent water, gas or the like fromV entering the casing at .the joints formed between the different vsized sections.

Seals have been provided for this purpose,

prior to my invention, such, for example, as

a seal comprising a single relatively large l and heavy lead ring applied to the u per end totighten. This type of seal also leaves they relatively soft lead exposed to injury by tools which from time to time are passed into the well. Also with this type of seal it is impossible to remove the smaller casing section after the seal has been madef Efforts have been made to overcome these objections, to some extent at least, by providing a seal comprising a hollow conical mem- 3" her threaded onto the upper end of thesmaller casing section, and providing a large and heavy single lead ring around the conical member, with one end internally beveled to thel same angle as the outside of the conical member, the opposite end of the ring being lat, for engagement with a similar fiat end of a setting head, which is threaded onto a cylindrical projection or the upper end of the conical member. By screwing the setting 4') head down on the conical member the heavy lead ring is expanded into sealing contact with the inner wall Qf the larger section of the casing.v

lVhile this latter construction to some extent overcomes the objections to the former construction by protecting the lead ring, nevertheless presents diculties, such as materially decreasing the diameter of the entrance into the smaller section of the casing,`due to the reduced diameter of the upper cylindrical end of the conical member on which the setting head is threaded.

With this latter construction the settin ing of the seal should occasion arise, but due eto the heavy construction of the single lead ring, expansion thereof, in the manner noted,

is a`n extremely difficult operation. Also with this construction it is impossible tb remove the smaller section of the casing, should such be required, as any attempt to raise the same will merely tend to further expand the lead ring, by raising of the conical member` and thereby forcing the ring into greater frictional contact with the 4inner wall of the larger section.

One object ofimy invention is to provide a casing seal in which4 the common single heavy lead ring is replaced by a plurality of rings of a comparatively lighter weight, and constructing the rings and the co-operating elements by which the rings are expanded in suoli a manner that the expansion thereof will be greatly facilitated, over the expansion of the common single heavy ring.

Another object of the invention is to construct the elements of the seal in such a manner that the lead rings will at all times be protected against injury by tools or other objects which from time to time are passed down through thewell casing and in such a manner that the seal will have a through passage of a diameter at least as great as the diameter of the smaller casing section, thereby eliminating all obstructions at the entrance to the smaller section.

Another object is to provide a seal which lshould be desired. The details of the conj struction of my improved casing seal will be 4fully disclosed hereinafter, reference being4 had to the accompanying drawings, of which: p

Fig. 1 illustrates a longitudinalsectional elevation of a pair of different sized casing sections in their relative set positions, and the sealing means located therein prio-rto its being set.v

Fig. 2 is a view similar to Fig. 1, but 'showing the sealing means in its set position Fig. 3 is al sectionalplan view taken on the line 3-3 of Fig. 2; and

Figs. 4, 5 and 6 are sectional elevations of modified forms of the invention.

Referring to Fig. 1, 1 illustrates a casing section having been loweredand permanently set in the ground. 2 illustrates a casing section of smaller diameter than the sec tion 1, having been similarly lowered and fset in the ground. In order to form. al seal between the adjacent coaxially aligned ends 3 and 4 of the respective sections 1 and 2, the end-4 of the section 2 is'externally threaded as illustrated at. 5, to receive internal threads 6 formed in one end of a sleeve 7. The co-operating threads 6 and 7 are tapered in accordance with standard pipe practice. The opposite end of the sleeve 7 -is also provided with internal tapered threads 6a, adapted to receive external tapered threads 8 on one end 9 of a nipple 10. The 'opposite end 11 of the nipple 10 is provided with external non-taperedv threads 12. A plain.external surface 13 isrformed on the nipple 10 between the threads 8 and 12 of the respect-ive ends@ and 11 thereof. In this construction the nipple 10 functions as va continuation of the section 2 and the sleeve7 functions as a shoulder on the said section 2. This construction may be replaced by the construction shown in Fig. 5f, in which the section 2a is provided with a shoulder in the forni of acollar 7a welded or otherwise rigidly secured to the section 2a.. The section 2a has non-tapering -threads`12a and a plain surface 13a corresponding to the threads 12 and surface 13 of the/nipple 10.

A setting head L15`is pwvided with internal non-tapering threads 16 at one end 17 thereof, which are adapted telco-operate with the non-tapering threads 12 on the end '11 of the nipple 10. The opposite end 18 of the setting head 15 is provided with a plain bore 19 which is adapted to receive one end of a -setting tool 20.

Around the nipple 10intermediate the up@ per interna'lly beveled end 21 of the -sleeve 7 and the lower externally beveled end 22 of the setting head 15, is mounted a plain sleeve 23 which is composed of pliable sheet copper or the like, and which is split longitudinally as illustrated at 24 in Fig. 1. Thesplit sleeve 23 has a flared end' 25 whichenga'ges lthe eX- ternally beveled end 22 of the setting head 15.

AThe sleeve 23 may have a butted joint at the line 24, or the respective longitudinal edges oi the sleeve may overlap as desired. The purpose of this split sleeve will be more fully disclosed hereinafter.

Around the split sleeve 23 is positioned a series of superposed annular- elements 26, 26

composedof relatively ysoft lead or like inaterial. The outer diameter of said rings is substantially equal or less than the outer diameters of the setting head 15 and the sleeve 7, in order that the relatively soft sealing material will be protected from injury by vthese other elements'when the casing section 2 is being lowered within the section 1.

Each ring 26 has an internally beveled end 28 of a predetermined'angle relative to the longitudinal axis of the element and an externally beveled end 27 of a greater angle, relative to the said longitudinal axis than that of the internal bevel 28.

The externally beveled end 27 of the lowermost sealing ring 26 is adapted to enter the vinternally beveled end 21 of the sleeve 7. The .externally beveledend 27 of each of the successively superposed rings enters the internally beveled end 28 of the adjacent ring next below. The externally beveled end 22' of the setting head 215 with the flared end of the split sleeve 23 thereover, enters the internally beveled end 28 of the uppermost packing ring 26. The angle of the externally beveled end 22 of the setting head 15 is substantially the same as the angle of the externally beveled end 27 of each ring 26.

From the above it will be seen that each opposed pair of faces on the setting head 15 and the superposed rings 26, are differentially beveled, which facilitates the expansion of the rings 26, when the setting head 15 is moved toward the sleeve 7, by 'causing the internally beveled face having the lesser angle to over-ride the externally beveled face of the `greater angle, thereby causing the internally beveled ends of the rings 26 to flare outwardly when initial longitudinal pressure isexerted on the rings, #thus making ,the expansion uniform and complete throughout the entire body of the sealing material.

The settingtool 20 is provided with a pair of laterally extending diametrically opposite lugs 30, 30` eachvof which is adapted to enter a longitudinal vertically extending slot 31 formed in the non-threaded end 18 ofthe setting head 15. f n

Each of the slots 3l`is provided with a horizontal extension slot 32 which is positioned at a right angle relative to the direction of the slot 3l. Each horizontal extension slot' 32 terminates in a socket 33, communicating with the extensionislot 32, said sockets ex tending vertically and vparallel to the entrance slots 3l.

The setting tool20 is further provided withr` a shouldered head 34 vwhich is adapted to besecured to the lower end of a lowering and when sealing shaft 35. This shaft 35 is the-usual secured to the end of the drill stem 35 in the manner illustrated in Fig. 1, and Jlugs 30 of the setting tool being positionedwithin the sockets'33 of the setting head 15. The

section 2 is then lowered to the bottom of the previously bored hole, after which the stem 35 is employed as a medium for rotating the head 15.

The setting head 15 is permitted to remain'` setting head l5. I

After the casing section 2 hasvbeenl lowered to the bottom of the hole, continued downward movement of the drill stem 35 causes the lugs to move out of the sockets 33 into the horizontal slots" 32 after which the stem or shaft 35 is turned, in the present instance in 'a clockwise direction, until the sides of the lugs 30, 30 engage the sides'38, 38 of the entrance slots 31. Such turningcof the stem 35 and setting tool 20 causes the straight or non-tapering threads 16 of the setting head 1 5 to move down on the straight or nontapering threads 12 of the end 11 of the nipple 10 until the externally beveled end 22 of the setting head 15 enters the internally beveled end 28 of the uppermost sealing ring 26',l

the externally beveled ends-of the respective sealing rings to subsequently enter the internally beveled ends of the adjacent rings, and the externally beveled end of the lowermost sealing ring to enterv the internally beveled end 21 of the sleeve 7. Continued rotation of the setting tool 2O by the stem 35 causes the setting head 15 to approach the threaded sleeve 7, and thereby longitudinally compress and radially expand the sealing rings 26, 26 into contact with the casing section 1 to form a gas and water tight seal between the endl 3 of the casing sectionhl and the nipple 10 attached by the sleeve 7 to the end 4 of the casing section 2, as shown inFig. 2.

.If desired, the nipple 10 and sleeve 7 may lbe made of one integal piece, but the construction shown is preferable for the convenience of manufacture. A The sleeve 7, nipple 10 and casing section 2 are rigidly assembled prior to the lowering of the section 2 into the hole, thus no subsequent relative rotation between these elements is effected during the sealing operation.

The split ,sleeve 23 functions to keep the 'comparatively' soft material, of which thev sealin rings 26 is composed, from being force into the threads l2 on the end l1 of the nipple l0 as the seal is being formed, the split 24 thereof permitting the said sleeve to spread over and adhere to the end 17 .of the setting head 15, as shown at 40 in 2,

the said setting head 15 vapproaches the sleeve 7.

When the seal is completed or set, the

setting tool 20 and the stem 35 are moved vertically, the lugs 30, 30, which, as above described, lie Within the entrance slots 31, 3l, during the seal forming operation, moving out of the entrance slots 31, 3lwithout fear of breaking the seal just formed, as might be the case if the horizontal slots 32, 32 extended in.

the opposite direction relative to the entrance slots, from that shown in the drawings and it were consequently necessary to reverse the direction ofuotary motion of the said setting tool in order to remove it from the setting Obviously if left hand threads are em# ployed on the end 11 of the nipple 10 and corresponding threads formed in the setting head 15, the direction of rotation of the setting head will be reversed from, that above described when the sealing operation is being effected, in whichvcase thedirection of the horizontal slots 32 will be accordingly reversed, in order that it will not be necessary to reverse the direction of rotation of the setting head from that employed in effecting the formation of the seal, to remove the setting tool from the setting head.

Under ordinary conditions, the casing section 2 is lowered into the pre-bored hole in the manner illustrated in Fig. 1, but, iffor any reason, such as binding of thescasing section in the hole, it would be necessary to exert a downward pressure on the casing section ashoulder 36 formed on the head 34 of the setting. tool 20 will engage the upper edge 37 of the setting hwead 15, thus relieving 'l the lugs 30, 30 of any strain resulting from the exertion of such pressure on the casing section.

The upper end 18 of the setting'head 15 is beveled inwardly, as illustrated at 41, and the end,11 of the nipple 10 is likewise beveled, as at 42, for the purpose of axially guiding any instrument which may be lowered into the well subsequent to the formation `of the seal between the respective sections thereof. The plain bore 19 of the .setting head 15 is of a diameter substantially equal to that of the interior of the nipple 10, which is substantially the same as the internal diameter ofthe casing section 2, and guides such instrument ing section 2, thereby protecting the ends of these elements during such insertion.

In Figl, I have illustrated a. modified form of setting head a in which the plain bore 19a there-of isof a greater diameter than set forth.

If it is desired to withdraw the smaller section of the casing after the seal has been per` lnanently set, this operation can be effected by reinsertin-g the drill stem 35 Withgthe setting tool 20 thereon into the head 15, the lugs 30 entering the entrance slots lfafter which the stem isturned until the lugs enter the extension slots 32 and subsequently the sockets 83. By applying sufficient lifting force to the stem 35, the sharp edge, formed at the juncture of the internal bevel21 and the outside face of the sleeve 7, will act as a shear to cut through the consolidated sealing mass formed by the rings 26, permitting the sec tion 2 to pass freely through the broken seal after the passage of the sleeve 7 therethrough. The inner Wall of the larger section acts as a means for resisting the upward movement of the sealing material and thereby assists in the shearing operation.

Upon referring to Fig. 2 of the drawings, it will be noted that the sealing material 26, which is necessarily vof a relatively soft or plastic nature, is completely enclosed by the elements 15, 10 and 7 of theseal which are of a substantially harder nature, thus the seal is protected against possible injury, which may result in a sections, when tools and other objects of varioils natures are passed down through the well.

It will also be noted that the opening extending completely through the seal is at least as great in diameter as the internal diameter of the smaller section 2 of the casing, thereby eliminating all obstructions at the entrance of the said smaller casing section. y

Obviously the plurality of expandible rings 26 may bel replaced by a single ring having an upper internally beveled face cooperating with the externally beveled face of the setting' head 15 and its lower end externally beveled to co-operate with the internally beveled face 21 of the sleeve 7, the opposed face being differentially beveled as above noted.

Fig. 6 illustrates -alternate rings 26a as being respectively provided with a pair of oppositely disposed externally beveled faces 27a, 27 a, and oppositely disposed internally beveled faces 28a, 28a. Expansion of the rings 26aV is effected in the same manner as leaky joint between the well the adjacent external bevels of adjacent rings.

I claim:

A seal, for well casings, comprising a plu- Y the internally beveled end of one ring resting against the externally beveled end of the next adjacent ring, providing a space between said l beveled faces, said'rings being adapted to be compressed longitudinally', whereby the Wedge action of the externally beveled ends acting Within toiare the internally beveled endsprogressively from the thin weak edge thereby' commencing and facilitating uni;

form radial flowing of the plastic rings into a homogeneous plastic mass completely filling, adapting itself to, and sealing the spaces j between. the said adjacent walls of the said telescoplng sections of the well casing. MARK Gr. STEWART.

above noted, the internal bevels overriding Y v

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