US2896724A

US2896724A - Cold flow preventing packing structures

Info

Publication number: US2896724A
Application number: US680102A
Authority: US
Inventors: John R Baker
Original assignee: Baker Oil Tools Inc
Current assignee: Baker Hughes Oilfield Operations LLC
Priority date: 1957-08-26
Filing date: 1957-08-26
Publication date: 1959-07-28
Anticipated expiration: 1976-07-28

Description

y 5 v I .J. 'R. BAKER 2,896,724

COLD FLOW PREVENTING PACKING STRUCTURES Filed Aug. 26, 1957 INVENTOR. clam/1?. finmse BY I Y Arraewzm Unilifid tates Patent COLD FLow PREVENTING PACKING,

STRUCTURES,

John. R. Baker, Pasadena, Calif., assignor tov Baker Oil 'flools, Inc., Los Angeles, Calif., a corporation of Caliornla A ca on u t a 2 .7 Se ial, a. 6. .0.10; Claims. (0!. 1661-204) The present. invention relates to subsurface well tools, and more particularly to packing devices adapted to be disposed i n'well bores foreifecting sealsagainst casings, liners, and the like, previously located. within the well bores. i

Packing elements employed in well boresare ordinarily made of rubber or rubber-like materials, or. similar pliant, elastic materials. The packing element usually bears against an abutment having a' substantialclearance with the wall of the surrounding well casing, liner, or the like. Upon being subjected to substantial forces, the packing element tends to cold flow into the clearance space aroundthe adjacent abutment. Such coldflowing action ismost pronounced in wellbores having relatively high temperatures and pressures. In some instances, the cold flowing is of such an extent as to result in the forcing of a large portion, if not all, of the packing material, into the clearance space, resulting in failure of. the packing element. i

'It is an object of the present invention to provide an improved packing structure embodying a pliant, elastic packing element whichis prevented-from cold flowing into the clearance space around an adjacent abutment, despite the fact that the packing element might be subjected to high pressures, high temperatures, or both Another object of theinverition is to provide a packing structure, which includes a pliant, elastic packing element and a coldflow preventing device for precluding shifting of the packing material around an adjacent abutment, the packing element being instrumental: in shifting the coldfiow preventing devic eto its operative position, there being no spaces in the preventing device through which he packing material can be forced.

This invention possesses many other advantages, and has other objects which may be made more clearly apparentffrom a consideration ofa forni in which it may be embodied. This form is shown in" the drawings accompanying and forming'part-of the present specification. It will now be described in detail, for the purpose of illustrating the general principles of the invention; but it is to be understood that such detailed description is not to be taken in a limiting sense, since the scope of the invention is best defined'by the appended claims.

Referring to the drawings:

Figure 1 is acombined longitudinal section and side elevational view of the well packer disposed in a Well casing, with the packer parts'in their initial, retracted positions; c v

Fig. 2 is a view similar to Fig. 1, illustrating the Well packer after it has been anchored in packed-off conditionin the well casing; i

Fig. 3 is a plan view of the flow preventing device, with parts broken away;

Fig. 4 is an enlarged fragmentary longitudinal section through the flow preventing device. a

The, packing. structure 10. is illustrated by way of example in the drawings as forming part of a Well packer A to be anchored inpacked-ott. condition within a well 2,896,724 Patented July 28, 1959 casing B, or the like. The well. packer itself is adapted to be lowered in the well casing to. the desired setting point by means ofa tubular string C, such as a string of tubing, with the exterior parts of the wellpacker disposed initially in a retracted'position to permit freedom of passage through the casing to the desiredsetting point; The packer includes a main body 11 which carries a set of upper segmental slips 12 adapted to be moved into engagement with the casing B by an upper frustoconical expander 13 retained initially in retracted position by one or more shear screws 14 securing it to the main body. The .upper slips are also retained initially in retracted and inelfective position by

shear screws

15, 16 securing them to the expander and the main body. A lower set of segmental slips 17 is initially held in retracted position, by being attached to the main body 11 through the medium of shear screws 18 and to a lower frusto-conical expander 19 through additional shear screws 20, this latter expander being held initially in inefiective position by suitable frangible connections in the form of shear screws 21 threaded into the body 11. The packing structure 10 includes a packing sleeve 22 of synthetic or natural rubber positioned between the expander's 13, 19, being retained initially free from contact "with the casing 'jwan, but being capable of foreshortening and expansion into engagement therewith and the main body 11 of thepacker. a

A valv e assembly housing 23 is threadedly secured to the lower end of the main packer body 11, carrying there. within atripping ball sea t 24 initially secur ed thereto by a shear This seat has i an upstanding "arm Z Gfor'hoIding a buoyant back pressure ball- 2 7 in ineffective position against the interior of the housing, to preventits: seating against a valve seat 28 provided at the aw reness thefinain body. *Rerrioval of "this arm 26 through a proper operation will permit the" ball '27 to be rqsit n da ns t qr b 'e a v '5??? 5 Whimi everreverse flowthroughjthe body 11 tends to occur. Thewell packer A "run in the casing' QB' to the desired setting point and olIiCllidtitlld established there} i h g nters any p e fi o e lma s in. th? well casing. Thereafter, a tripping ball is lowered or Pa r l wn i sueh t e t n String G. t e t engagement with thetripping ball seat 24, permitting inre se'st' s P ess e 9 b? i wi l he. fl s s? d'y. '1 an i s ge h ugh, P P-" earni through the'body into thelinteriorof the packing sleeve flu i u s Pre u w l a th srs and h t th ur'r r' expander rwa' d Y l n he body '11 to disrupt the various shear screws 15, lo and if he rr lip g an u pe et g n se u sdt t e o n su wl r l nt g ipp n engagement with the well casing B After the upper sl-ips i2" have been set the manner described, the r s r c he fl s is nf as 9; shea h S r w ho d het i p n ba ea t e alvsh usin I 61 u sie i h e .21 wea her W h its piii m. r m the al e o sin a llowin theback pressure ball 27 'to engage theseat 2.8 whenever reverse flowof fluid tends to occur. 7

Anupwardly dir cted pull": train then taken on ar S r n 0 unma od .1 f the P e fi i j rtntherak a. sl e 22 by. mov n e jl w ex ande 2 ward hbjupper p n e 13 and x ml: he a kin sle ve ainstft e. cas ng w l s L tb o the ma n bdy 1.1 A con u n of h ly e l s st e n. a the ubul trln v c. and ibody B w ill shear the screws-1Q, 2]), 21- holding the lower s ips-1 7101% bddyfand expander' 1 9, aiidthe expander 19to the' body1l,' ".c ausia'g an abutment "32 at the lower end of the" body a 11 to engag'flief" slips 17 and move them longitudinally along the outer face of the lower expander 19 and radially into engagement with the casing B. An increase in this upward strain will further move the lower slips 17 and expander 19 toward theupper slips 12 and expander 13, further compressing the packing sleeve 22 between the casing wall B and exterior of the body 11,to effect aleakproof seal therebetween.

The parts are retained in the set position illustrated in Fig. 2 .by preventing downward movement of the body 11 relative to the part surrounding it. This can be accomplished by providing a split, contractile ratchet ring 33 in an internal groove 34 in the upper expander 13, this ratchet ring being adapted to engage circumferential ratchet teeth 35 formed in the periphery of the packer body. The teeth 35 on the body face in a downward direction whereas the ratchet ring faces in an upward direction, so as to permit the body 11 to move upwardly relative to the upper expander 13, but precluding downward movement of the body with respect thereto.

The upper and

lower expanders

13, 19 form abutments at the upper and lower ends respectively of the pliant, elastic packing element or sleeve 22. As disclosed, the end portions 22a of the packing sleeve may be reduced in diameter to fit in companion recesses 40 in the upper and lower abutments or expanders. To assure the passage of the well packer A down through the fluid in the well casing B, a substantial annular clearance 41 is provided between the abutments or

expanders

13, 19 and the wall of the surrounding well casing. Such annular clearance space is a source through which the rubber or rubber-like packing material 22 can be extruded, following the setting of the packer and expansion of the packing sleeve 22 into sealing engagement between the body 11 of the tool and the wall of the well casing B. Such extrusion can occur more readily when the well packer is subjected to high temperatures or high pressures, and will occur most readily when the packing sleeve is subjected to a combination of high pressures and high temperatures.

The present invention prevents the cold flowing or extrusion of the packing material through the clearance space 41 existing between an

abutment

13 or 19 and the wall of the surrounding well casing B. To accomplish this purpose, an extrusion preventing device 42 is provided at each end portion of the packing sleeve 22 and the adjacent abutment or expander. As specifically disclosed, the end 43 of the upper abutment 13 is tapered in an upward and outward direction, the confronting portion 44 of the packing sleeve 22 also being tapered, but in a downward and outward direction, thereby defining a generally triangularly-shaped groove 45 between the

tapered surfaces

43, 44 which extends circumferentially around the abutment and the confronting portion of; the packing sleeve. An outer metallic ring 46 is positioned in the groove 45, having an inner tapered surface 47 engageable and companion to the tapered surface 43 on the abutment. This ring is also of generally triangular cross-section. In fact, it may be of generally right triangular cross-section, with its outer surface 48 generally cylindrical, and with its lower surface 49 relatively flat and substantially normal to the axis of the well packer.

A-n inner ring 50, reversely arranged to the outer ring 46, is also disposed in the lower. portion of the groove 45, having a tapered inner surface 51 engageable with and companion to the tapered surface 44 on the packing sleeve 22. This inner ring 50is also of generally triangular cross-section. As specifically disclosed, it is of generally right triangular cross-section, with its outer surface 52 generally cylindrical and forming a continuation of the outer surface 48 of the other ring 46. Its upper surface 53 may also be normal to the axis of the well packer and abuts the lower surface 49 of the outer ring The inner and

outer rings

50, 46 substantially fill the triangular groove 45 defined by the tapered surfaces 43, 44 on the upper abutment 13 and the confronting face of the packing sleeve 22. These rings are each split and normally tend to remain in a retracted position, such as disclosed in Fig. 1. However, the

rings

46, 50 are expandible outwardly to bring their

cylindrical surfaces

48, 52 into engagement with the cylindrical wall of the well casing B. The

splits

60, 61 of the rings are staggered with respect to each other. In fact, they are preferably arranged approximately degrees from. one another.

To assure the same extent of outward expansion of the rings, they are keyed to one another, for circumferential slidable movement with respect to one another, but with relative radial movement being prevented, by an arcuate key and slot arrangement. As specifically disclosed, one of the rings 50 has a circumferential r-ib 62 projecting upwardly from its upper face 53, this rib fitting within a companion circumferential groove 63 in the lower portion of the outer ring 46. By virtue of the key and keyway or'slot arrangement 62, 63 described, the

rings

46, 51 will expand outwardly to the same extent, as described hereinbelow. However, the interconnection 62, 63 between the rings will not prevent .such expansion from occurring. By placing the

splits

60, 61, 180 degrees from one another the rings together exert a uniform force around their circumference resisting their outward expansion.

. If desired, a similar flow preventing device 42a may be provided between the lower expander or lower abutment 19 and the confronting portion 44a of the packing sleeve 22.

In the operation of each flow preventing device, when the packer body 11 is moved in an upward direction, after the upper set of slips 12 has been expanded against the well casing B, in the manner described above, the lower abutment or expander 19 is moved by the body toward the upper abutment or expander 13, foreshortening the packing sleeve 22 andcausing it to shift outwardly against the wall of the well casing. During the foreshdrtening of the packing sleeve between the

abutments

13, 19 and its outward expansion, the tapered surface 44 on the packing sleeve bears against the tapered surface 51 on the inner ring 50 and urges the latter in an outward direction toward the wall of the well casing.

The upward force imparted to the packing sleeve 22 is transmitted through the inner ring 50 to the outer ring 46, the tapered surface 47 of the latter bearing upon the companion tapered surface 43 on the upper expander or abutment 13, which also effects an outward shifting of the outer ring 46 toward the well casing B. The combination of the tapered surfaces 44, 43 on the packing sleeve 22 and on the'abutment 13 shifts the

outer rings

46, 50 outwardly, such rings moving outwardly to the same extent in view of their arcuate or circumferential key or rib and groove or slot interconnection 62, 63, until both rings are brought into firm engagement with the wall of the well casing. When so engaged, the outer ring 46 still has substantial engagement with the abutment 13. Each ring will contact the wall of the well casing for substantially 360 degrees, except for the arcuate extent of

split

60 or 61 in each ring. However, since the slots or splits 60, 61 are staggered with respect to one another, the inner and

outer rings

46, 50 of each flow preventing device will engage the wall of the 'well casing B and bridge the clearance space 41 between the abutment :13 and the-well casing, no gaps or spaces existing through the flow preventing device 42 into and through which the packing material can flow (Fig. 2).

If the lower flow preventing device 42a is used it will also be expanded outwardly as a result of the longitudinal forces imposed upon the packing sleeve 22, the inclined surfaces coacting with one another to effect a shifting of both

rings

46, 50 of the lower device outwardly until their

cylindrical surfaces

48, 52 engage the wall of the well casing B.

The

rings

46, 50 of each

extrusion preventing device

42, 42a may be made of a suitable material which will withstand comparatively high pressures and temperatures without deforming their cross-section. For example, the rings may be made of ductile iron. When made of such material, the rings will not deform significantly and will always bridge the clearance space 41 between each abutment and the wall ofthe well casing, resisting extrusion into the clearance space.

' The inventor claims:

1. A packing structure, including a non-metallic packing member adapted to engageia companion wall, an abutment adjacent said member and having a tapered expander surface, a first split functionally integral ring engaging said packing member, a second split functionally integral ring engaging said tapered surface and said first ring and circumferentially slidable on said first ring, and means securing said rings to one another for joint movement toward engagement with the companion wall in response to movement of the packing member into engagement with the companion wall.

2. A packing structure, including a non-metallic packing member adapted to engage a, companion wall and having a first tapered expander surface, an abutment adjacent said member and having a second tapered expander surface opposite said first expander surface, a first split ring engaging said first tapered surface, a second split'ring engaging said second tapered surface and said first ring and circumferentially slidable on said first ring, and means securing said rings to one another for joint movement toward engagement with the companion wall in response to movement of the packing member into engagement with the companion wall.

3. A packing structure, including a non-metallic packing member adapted to engage a companion wall and having a first tapered expander surface, an abutment adjacent said member, a first split ring engaging said tapered expander surface, a second split ring engaging said abutment and said first ring and circumferentially slidable on said first ring, and means securing said rings to one another for joint movement toward engagement with the companion wall in response to movement of the packing member into engagement with the companion wall.

4. A packing structure, including a non-metallic packing member adapted to engage a companion wall, an.

abutment adjacent said member, a first split functionally integral ring engaging said packing member, a second split functionally integral ring engaging said abutment and said first ring and circumferentially slidable on said first ring, and means securing said rings to one another for joint movement toward engagement with the companion wall in response to movement of the packing member into engagement with the companion wall.

5. A packing structure, including a non-metallic packing member adapted to engage a companion wall, an abutment adjacent said member, a first split ring engaging said packing member, a second split ring engaging said abutment and said first ring and circumferentially slidable on said first ring, one of said rings having an arcuate groove therein, and an arcuate rib on the other of said rings disposed in said groove to cause both of said rings to move jointly toward engagement with the companion wall in response to movement of the packing member into engagement with the companion Wall.

6. A packing structure, including a non-metallic packing member adapted to engage a companion wall and having a first tapered expander surface, an abutment adjacent said member and having a second-tapered expander surface opposite said first expander surface, a first split ring engaging said first tapered surface, a second split ring engaging said second tapered surface and said first ring and circumferentially slidable on said first ring,

- 6 one ofsaid rings having an arcuate groove therein, the other of said rings having an arcuate rib disposed said groove to cause said rings to move jointly toward engagementwith the companion Wall in responseto movement to the packing member into engagement with the companion "wall.

7. A packing structure, including a non-metallic packing member adapted to engage a companion surrounding wall and having a first tapered expander surface, an abutment adjacent said member andhaving a second tapered expander surface opposite said first expander surface, a first split ring engaging said first surface and having a generally cylindrical outer surface, a second splitring engaging said second surface and having a generally cylindrical outer surface, and means securing said rings to one an; other for circumferentially shiftable relation to each other and for joint outward expansion into engagementwith the surrounding wall in response to movement of the packing member toward said abutment and into engagement with thecompanion wall.

8. A packing structure, including a non-metallic packing member adapted to engage a companion surrounding wall and having a first tapered expander surface, an abutment adjacent said member and having a second tapered expander surface opposite sai d first expander surface, a I

first split ringengaging said first surface and having a, generally cylindrical outer surface, a second split ring engagingsaid second surface and having a generally cylindrical outer surface and circumferentially slidable on said first ring, one of said ringshaving an arcuate groove therein, and an arcuate rib on the other of said rings disposed in said groove to cause said rings to expand jointly into engagement with the surrounding wall in response to movement of the packing member toward said abutment and into engagement with the surrounding wall.

9. A packing structure, including a non-metallic packing member adapted to engage a companion surrounding wall and having a first tapered expander surface, an abutment adjacent said member and having a second tapered expander surface opposite said first expander surface, a first split ring of generally triangular cross-section having a tapered surface engaging said first surface and also having a generally cylindrical outer surface, a second split face and disposed in said arcuate groove to cause said. rings to move jointly outwardly into engagement with the surrounding wall in response to movement of the packing member towards said abutment and into engagement with the surrounding wall.

10. A packing structure, including a non-metallic packing member adapted to engage a companion wall, an abutment adjacent said member and having a tapered expander surface, a first split functionally integral ductile ring engaging said packing member, a second split functionally integral ductile ring engaging said tapered surface and said first ring and circumferentially slidable on said first ring, and means securing said rings to one another for joint movement toward engagement with the companion wall in response to movement of the packing member into engagement with the companion wall.

ll. A packing structure, including a non-metallic packing member adapted to engage a companion wall, an abutment adjacent said member, a first split functionally integral ductile ring engaging said packing member, a second split functionally integral ductile ring engaging said abutment and said first ring and circumferentially slidav rings disposed in said groove to cause both of said rings to move jointly toward engagement with the companion wall in response to. movement of the packing member into engagement with the companion Wall.

12. A packing structure, including a non-metallic packing member adapted to engage a companion surrounding wall and having a first tapered expander surface, an abutment adjacent said member and having a second tapered expander surface opposite said first expander surface, a first split functionally integral ductile ring engaging said first surface and having a generally cylindrical outer surface, a second split functionally integral ductile ring engaging said second surface and having a generally cylindrical outer surface, and means securing said rings to one another for circumferential shifting relative to each other and for joint outward expansion into engagement with the surrounding wall in response to movement of the packing member toward said abutment and into engagement with the companion wall.

13. A packing structure, including a non-metallic packing member adapted to engage a companion wall, an abutment adjacent said member, a first split functionally integral ductile ring engaging said packing member, a second split functionally integral ductile ring engaging said abutment and said first ring and circumferentially slidable on said first ring, and means securing said rings to one another for joint movement toward engagement with the companion wall in response to movement of the packing member into engagement with the packing -wall.

14. A packing structure, including a non-metallic packing member adapted to engage a companion surrounding wall and having a first tapered expander surface, an abutment adjacent said member and having a second tapered expander surface opposite said firstexpander surface, a first split functionally integral ductile ring, a generally triangular cross-section having a tapered surface engaging said first surface and also having agenerally cylindrical outer surface, a second split functionally integral ductile ring and generally triangular crosssection having a tapered surface engagingsaid second surface and also having a generally cylindrical outer surface, said rings being circumferentially shiftable relative to each other and having opposed surfaces substantially normal to said outer surfaces and engaging one another, one of said rings having an arcuate groove extending in an axial direction inwardly from its normal surface, and the other of said rings having an arcuate rib projecting axially from its normal surface and disposed in said arcuate groove to cause said rings to move jointly outwardly into engagement with the surrounding wall in response to movement of the packing member toward said abutment and into engagement with the surrounding wall.

References Cited in the file of this patent UNITED STATES PATENTS 2,368,928 King Feb. 6, 1945 2,546,377 Turechek Mar. 27, 1951 2,695,068 Baker et al Nov. 23, 1954 2,726,722 Baker Dec. 13, 1955