US2917352A

US2917352A - Swab cup

Info

Publication number: US2917352A
Application number: US742956A
Authority: US
Inventors: Jr Raymond G Taylor
Original assignee: Borg Warner Corp
Current assignee: Borg Warner Corp
Priority date: 1958-06-18
Filing date: 1958-06-18
Publication date: 1959-12-15
Anticipated expiration: 1976-12-15

Description

Dec. 15, 1959 R. G. TAYLOR, JR 2,917,352

SWAB CUP Filed June 18, 1958 2 Sheets-Sheet 1 Dec. 15, 1959 R. G. TAYLOR, JR

SWAB CUP 2 Sheets-Sheet 2 Filed June 18, 1958 INVENTOR. QM/MMO GLM/02.4K?

@Mu/M SWAB CUP Raymond G. Taylor, Jr., Santa Monica, Calif., assignor to Borg-Warner Corporation, Chicago, lll., a corporation of Iliinois Appli-maan June 1s, 195s, serial No. 742,956 14 claims. (ci. 309-33) The present invention relates to swab cups or rubbers, and more particularly to an improvedswab cup particularly adapted for use in a swab assembly such as that disclosed in my copending application, Serial No. 742,958 led concurrently herewith, although it will be understood that various features of the present invention may be advantageously employed in swab cups in general.

Swabbing of wells is ordinarily resorted to following well completions, for swabbing the wells into production, or following well treatments such as hydraulic fracturing of the formation and/or acidizing or cleaning of the formation and the like, for pulling the treating uid from the well bore to enable the formation pressure to cause the well to produce.

Inasmuch as swabs frequently are run into wells which are many thousands of feet deep, it is preferable that the swab be capable of rapid friction-free descent into the well. Therefore,'an object of the present invention is to provide a swab cup for'use in a swab assembly, the cup being so constructed that the swab assembly will fall freely through the well uids in the well tubing'vor the like, without objectionable frictional engagement of the cup with the tubing Wall.

In the swabbing of wells where cup-type swab rubbers :are employed'which are not inherently capable of lthemselves dumping loads above a predetermined value, it is highly desirable that the swab cup be s` constructed as to lift in the tubing a substantial column of well fluids. In so doing, swab cup rubbers are subjected to severe ywear conditions as they move upwardly through well :tubing in sliding contact therewith. In the case, for exzample, where the swab is being retrieved from a well depth on the order of 10,000 feet, the swab'rubbers are continuously subjected to the wearing effect of sliding contact with the well tubing under pressure from the hydrostatic head above the swab rubbers. As hydro- `:static heads increase, then likewise frictional engagement of the swab cups with the well tubing increases.

Among the primary objects of the present invention is the provision of a swab cup rubber which is capable yof lifting an exceptionally heavy column of fluid through .a long string of well tubing, wherein the life of the swab rubber or cup is substantially improved in contrast with .swab cups heretofore available.

A further object of the invention is to provide a swab cup having axially spaced pressure-responsive internal ,areas subjected to the pressure of the column of well fluid being elevated in a well tubing, and wherein there is molded into the body of the cup or rubber, load-compensating means whereby as pressure is increased on the respective pressure-responsive areas aforesaid, the loadcompensating means acts to offset the effect of pressure upon the respective opposite pressure-responsive areas in such a manner as to reduce the frictional contact of the swab cup or rubber with the well tubing.

More particularly, it is an object of the invention to provide a swab cup or'rubber including an internal core or tubular member on which is molded acup-like rubber 2,917,352 Patented Dec. 15, 1959 ice body, the body having imbedded therein a series of circumferentially spaced longitudinally extended load-com-- pensating wire elements, these wire elements being secured against radial movement relative to the lower end of the swab cup, and being secured at a point intermediate their ends against radial outward movement relative to 'the tubular member by means of a fulcrum ring embracing the wires and about which the wires tend to pivot as a result of pressure applied to the rubber cup above and below*V the fulcrum.

Another object is to provide a swab cup or rubber in accordance with the foregoing, wherein the load-compensating Wire members are adapted to slidably engage the well tubing so as to provide relatively wear-resistant bearing surfaces, thus to increase the longevity of the swab rubber.

Other objects and advantages of the invention will be hereinafter described or will become apparent to those skilled in the art, and the novel features thereof will be defined in the appendedv claims. y

In the accompanying drawings:

Fig. 1 is a view partly in longitudinal section, and partly in elevation, showing a swab assembly including a pair of swab cups made in accordance with the invention and disposed within well tubing;

.FigLZis a view in elevation showing the swab cup hereof;

Fig. 3 is a fragmentary transverse sectional View on an enlarged scale as taken on the line 3 3 of Fig. 2;

Fig. 4 is a fragmentary transverse sectional view on an enlarged scale as taken on the line 4-4 of Fig. 2;

Fig. 5 is a detail view in elevation, showing one of the load-compensating and reinforcing wires of the swab cup hereof;

Fig. 6 is a view in transverse section showing a plu-` rality of the wires of Fig. 5 disposed in circumferentially spaced relation similar to that assumed by the wires when molded in the swab rubber, the wires being in section on the plane of the line 6 6 of Fig. 5;

Fig. `7 isan enlarged fragmentary view in longitudinal section illustrating the condition of the swab cup hereof during running of the latter into a well;

Fig. 8 is a view similar to Fig. 7, but illustrating the condition of the cup when subjected to a light load;

Fig. 9 is a view similar to Figs. 7 and 8, but illustrating the condition of the swab cup when subjected to a heavier load;

Fig. 10 is a view corresponding to Figs. 7 through 9, but illustrating the condition of the swab cup when subjected to a still heavier load; and

Fig. 11 is a view corresponding to Figs. 7 through 10, illustrating the swab cup in a condition of maximum deflection of the load-compensating wires when the cup is subjected to an extremely heavy load.

, Referring to Fig. 1 particularly, a swab assembly is shown, the assembly being disposed in well tubing T and including `a mandrel M comprising an elongated body 1, having at its upper extremity a connector head 2, provided with a threaded stem 3 for connection to a wire line rope socket (not shown). The connector head 2 is provided with opposed arcuate faces 4-4 converging on the lower extremity of the head 2, and forming therewith radially extended abutments or shoulders 5, for a purpose which will hereinafter appear.

At the lower extremity of the body 1 is a guide nose 6, having an upper tapered seating surface 7, and a plurality of circumferentially spaced ribs 8 adapted to engage the tubing T to centralize the mandrel M therein, there .being fluid flow passages or flutes 9 between the ribs 8- for enabling rapid lowering of the mandrel through well fluids in the tubing T. The body 1 of the .mandrel is also provided with a plurality of longitudi.- z

nally extended circumferentially spaced Aribs 11 definingv From a general standpoint, eachfof the swab rubbersy S includes a central core or tubularmember 13 having an outwardly flared `base portion 14. Molded on the tubular member 13 is a rubber body or cup 15, in which is imbedded a plurality of longitudinally-extended reinforcing and load-compensating wires :16the wires being is bonded to the outer periphery of the core 13 and is provided with a sealing lip as at 15a which serves to prevent the admission of fluid-pressure wedges into the juncture of the rubber body with the core.

As particularly shown in Fig. 2, the wire sections 16b of the fingers 16, except for the indentation 16e and the lower section of the wires located beneath the bend 16d, are positioned in-the rubber body 15 so as to be constrained by a load-compensatingLring 17 extending thereabout intermediate the opposite endspf the wires, and a cup-like thimble 18 extending about the lower extremity of thewwires.

Internally of the ared base section 14 ofthe tubular member 13 is a'generally triangularlyrubber yvalve head 19, adapted to seatupon the Atapered-seating surface 7 of the nose 6, as will be more particularly described hereinafter. The valve'` head 19 is 4of annular formation and generally triangular in cross'section,.having a seating face 19b, aface 19e bonded to the-'flared section 1'4 of tubular member 13 anda face -1.9a;opposing.uid

pressure within the rubber S when the .valve head 19 is seated on conical seat 7. At the upper extremity of the tubular member13 of each swabrubber S thereis a reinforcing ferrule or ring `20 having a radial flange 21 thereon overlying thefend ed'geof the tubular mem-V ber 13 and providinga valve seat engageable with a valve head 19 of a swab cup S thereabove. Accordingly, when a plurality ofthe swab rubbers or cups S are disposed upongthemandrel M,the valve head 19 of .the lowermost rubber1S-will beengageable with the conical seating surface 7 of nose 6 to prevent leakage of fluid from the lower cup or rubber S and leakage between the;cu'ps'or rubbers S- will beprecluded vby means of the complemental valve head and seat between adjacent rubbers S.

VEach of the reinforcing-and load-compensating wires 16 is substantially in the form of a hairpin, as more particularly 'shown in Fig. 5, and includes a base section 16a at which the wire is turned back upon itself to provide identical wire arms 16b-16b, the wire arms at thebase section 16a extending generally parallel to one another to a point 16e where the arms lare bent relative to one another, so -as to diverge slightly and so as-to project at an angle to the plane of the parallel wire portions of the base section 16a. At 16d thevwire sections 16b are again bent,-so that they extend in -substantially parallel relation to one another in a plane which is in radially spaced parallel relation to the plane of base section 16a. Intermediate the bend 16d and the upper extremity of thewire sections 16b, each section is indented as at 16e, and at its upper extremity each wire section 1Gb is bent inwardly-as at 161. During molding of the swab rubber S, the base sections of'adjacent wires will be engageable with one another when the wires are disposed in a circumferential series about the core 13. The angle of divergence of the wire arms between the bends 16a` and .16d is such that the arms of the circumferential series of wires above the bends 16d vwill be equally spaced about the-core 13.

In the manufacture of one of the swab rubbers S a series of the hairpin type wires 16 are disposed in cir-v cumferentially spaced relation, as shown in Fig. 6, with' the base sections 16a disposed in the annular space between the cup-likethimble 18 and the opposing outer periphery of the tubular member or core 13. During molding of therubber body 15, the base sections 16a of the wires-are preferably substantially surroundedby the rubber material. The-rubber body is generally cupshaped,A and throughout the major part of its axial dimensiontf isz spaced from the core or tubular member 13.` However,l at= a pointv between the Vindentation 16e and-"the bend 16d ofthe wires, the 'rubber Vbody-'15;V

slightly exposed along ,the outer surface of the swab rubber S for engagement with the well tubing, so as to provide relatively wear-resistant bearing surfaces which will slide in the tubing though loaded into engagement therewith under a substantial force.

Referring now to Figs. 7 through `l1, Yit will be observed that the ring 17 encircles the circumferentially spaced wires 16 at the indentation 16e of the latter, this ring 17 being suiciently rigid so as to withstand the normal radial loadsimposed thereon without deflection, so that the wires y16 are rigidly supported within the ring 17 -against bodily deflections in a radial direction. However, the -ring `17 provides a fulcrum about which the wires 16'are mounted. Internally of the cup 15 of the swab rubber S there are axially spaced pressure-responsive areas designated 15b and 15e; the area 15b extending from the ring 17 to the upper extremity of the body 15, and the pressure-responsive area 15e` extending from the;indentation.16e to the lip 15a referred to above.

Sinceetheupper section of the body 15, i.e.,the section of thesbodyabove ring 17, is not supported against radial expansion,it is relatively flexible and is adapted to be flexed into engagement with the tubing T under comparatively light pressuresacting on area 15b. However, the wires V16 from the ring 17 to the thimble 18 are supported againstradial expansion at both points, andtherefore the lower Vsection of the body 15, i.e. the section of the body -between ring'17-and thimble 18, will not-readily'ex'into lengagement with the tubing'T, and substantially higher pressures are required to flex the lower section of the body 15 than are required to flex the upper section of the body 15.

Preferably the swab rubbers S will be so constructed that a slight clearance will be provided between the outer periphery thereof andthe tubing T as a swab assembly is being run into -a-well. This will enable rapid descent of a-swab assembly without interference from frictional engagement of theswab rubbers with the tubing wall.

fUpon the imposition on the pressure-responsive area 15b of pressures resulting from a comparatively light load ofuid in-thetubingabove the swab on commencementof retrieval thereof, the upper section of the swab rubbeiwill flex radially outwardly about the load-compensating ring 17 into engagement `with the tubing T, so-asto prevent the leakage therebetween of well fluids abovethe swab. VAt the same time, valve head 19 will engage the tapered seating surface 7 of the mandrel nose'6, previously described, to prevent leakage of the well uidsfrom within the central core 13 of the swab cup or rubber S.

The reference to light pressures in the foregoing contemplates pressures on the order of 20 p.s.i., more or less, so that the swab cup hereof is capable of lifting asmall volume of fluid without leakage. When the head of Huid in the tubing above the swab cup S is such that pressures` on the order of 500 p.s.i. are imposed upon the pressure-

responsive areas

15b and 15e, the upper section of the cup.15 will be forced more tightly into engagement with the tubing T and the valve head 19 will be compressed :slightly against the tapered seating surface 7 of mandrel nose 6, as shown in Fig. 9, the lower extremity of the flared end 14 of the central core or tubing 13 being forced substantially into metal contact with the tapered seating surface 7. However, since the lower-sectionof thecup 15 intermediate the loadported than the upper section of the cup, the lower section of the cup will not contact the tubing T.

As pressures acting on the pressure-responsive area 15C, increase; that is, when heavier loads of well uid are being lifted by the swab, the lower section of the body 15 will be deflected suiciently to come into contact with the tubing T as shown in Fig. 10, say, as the result of pressures on the order of l,000,p.s.i. being imposed upon the pressure-responsive area 15C. Upon the imposition on the area 15e of an even higher pressure; say, on the order of 1,500 p.s.i., the lower section of the body 15 will be forced further radially into engagement with the tubing T, as particularly shown in Fig. 11.

In view of the fact that the indented section 16e of .the wires 16 provides a fulcrum for each wire for engagement with the rigid ring 17 which will not deflect under radial forces, it will be recognized that pressures acting on area 15b, tending to cause pivotal movement of the respective wires 16 about the ring 17, will tend to counteract the effect of pressures acting on area 15a. Likewise, pressures acting on the area 15e will tend to force the lower section of the cup 15 into engagement with the tubing T while effecting movement tending to move the wires 16 about the ring 17 to offset the efect of pressure acting on the area 15b; thus, in effect, the pressures acting at the upper and lower sections of the cup tend to compensate for pressures acting upon the lower and upper sections of the cup respectively. This unique characteristic of the swab cup hereof diminishes the tendency of internal pressures in the cup to effect such engagement of the exterior of the cup with the tubing as to cause rapid wear and deterioration of the swab rubber, as is characteristic of swab rubbers heretofore available.

As iluid loads in the tubing increase, then the valve head 19 of the lowermost cup or rubber S must more tightly seal against leaking across the conical seat 7 of nose 6. This is accomplished as shown in Figs. 7 through 11 and is more particularly described in my companion application Serial No. 742,958, referred to above.

While the specific details of one illustrative embodiment of the invention have been herein shown and described, changes and alterations may be resorted to without departing from the spirit of the invention as del-ined in the appended claims.

I claim:

1. A well swab cup comprising: an elongated rigid` core adapted to be disposed on a supporting mandrel, said core having a cup like rubber body molded thereon, said body including a lower section connected to said core and an upper free section, a plurality of circumferentially spaced longitudinally extended reinforcing members embedded in said body, means providing a fulcrum for said reinforcing members between said body sections, said reinforcing members having a lower end in said lower body section restrained against movement away from said core and a free upper end in said upper body section.

2. A well swab cup comprising: an elongated rigid core adapted to be disposed on a supporting mandrel, said core having a cup like rubber body molded thereon,

, said body including a lower section connected to said core and an upper free section, a plurality of circumferentially spaced longitudinally extended reinforcing members embedded in said body, means providing a fulcrum for said reinforcing members between said body sections, said rein-forcing members having a lower end in said lower body section and an upper end in said upper body section, and a constraining member disposed about said lower ends of said reinforcing members for preventing movement of said lower ends away from said core.

3. A well swab cup comprising: an elongated rigid core adapted to be disposed on asupporting mandrel,

said core having Va cup like ,rubber body molded thereon, said body including a lower section connected to said core and anupper free section, a plurality of circumferentially spaced longitudinally extended reinforcing members embedded inl said body, means providing a fulcrum for said reinforcing members between said body sections, said reinforcing members having a lower end in said lower body section and an upper end in said upper body section, an annular member disposed about said core in spaced relation thereto and defining with said core a space in which lower ends of said reinforcing members are disposed, and said space being filled with rubber surrounding said lower ends of said reinforcing members.

4. A well swab cup comprising: an elongated rigid core adapted to be carried by a supporting member, said core having molded thereon a cup like rubber body, said body having a lower section attached to said member and an upper free section, saidbody having inner fluid pressure responsive areas on the respective upper and lower body sections, and reinforcing means in said cup like body responsive to fluid pressure applied to said pressure-responsive areas, for causing a contractive force to be applied to one of said pressure responsive sections upon pressure responsive expansion of the other pressure responsive section.

5. A well swab cup comprising: an elongated rigid core adapted to be carried by a supporting member, said core having molded thereon a cup like rubber body, said body having a lower section attached to said member and an upper free section, said body having inner fluid pressure responsive areas on the respective upper and lower body sections, reinforcing means in said cup like body responsive to iluid pressure applied yto said pressureresponsive areas, for partially compensating for fluid pressure applied to the respective opposite pressure-responsive areas, said reinforcing means including a plurality of circumferentially spaced longitudinally extended members having upper and lower end portions respectively disposed in the upper and lower body sections, means constraining said lower end'portions of said reinforcing members against movement relative to said core, and means providing a fulcrum for said reinforcing members intermediate said upper and lower body sections.

6. A well swab cup comprising: an elongated rigid core adapted to be carriedby a supporting member, said corehaving molded thereon a cup like rubber body, said body having a lower section attached to said member and an upper free section, said body having inner fluid pressure responsive areas on the respective upper and lower body sections, reinforcing means in said cup like body responsive to fluid pressure applied to said pressureresponsive areas, for partially compensating for fluid pressure applied to the respective opposite pressure-responsive areas, said reinforcing means including a plurality of circumferentially spaced longitudinally extended members each having a lower end disposed in said lower body section and an upper end disposed in said upper body section, said reinforcing members having an indented intermediate portion, means providing a fulcrum for said reinforcing members intermediate said upper and lower body sections, and said fulcrum means comprising a rigid ring embracing said reinforcing members and disposed in said indented portion thereof.

7. A well swab cup comprising: an elongated rigid core adapted to be carried by a supporting member, said core having molded thereon a cup like rubber body, said body having a lower section attached to said member and an upper free section, said body having inner uid pressure responsive areas on the respective upper and lower body sections, reinforcing means in said cup like body responsive to uid pressure applied to said pressureresponsive areas, for partially compensating for fluidv 7 pressure applied -to the respective opposite pressure-responsive areas, said reinforcing means including a plurality of circumferentially spacedlongitudinally extended memberseach having alower en d disposed in said lower body section and an'upper en'd disposed in said upper body section, said lower'bodyV section having a rigid cy'- lindrical member disposed about said core,l said reinforcingmernbers having abase section disposed between said core and .said cylindrical member, and means providing a vfulcrum for 4said members intermediate said upper and lower body sections.

8 A well swab cup comprising: an elongated rigid c ore adaptedto becarriedby a supporting member, said core having molded thereon a cup like rubber body, said body having a lower section attached to said member and an upper free section, said body having inner fluid pressure responsive areas on the respective upper and lower body sections, reinforcing means in said cup like body responsive to fluid pressure applied to said pressureresponsive areas, for partially compensating for fluid pressure applied to the Yrespective opposite pressure-responsive areas, said reinforcing means including a plurality of longitudinally extended circumferentially spaced hairpin members having an upper end in said upper body section and a lower end Vin said lower body section, means constraining said lower end of said hairpin members against movement away from said core, and means providing a fulcrum for said ,hairpin members intermediate said upper and lower body sections.

9. A well swab cup comprising: an elongated rigid core adapted to be carried by a supporting member, said core having molded thereon a cup like rubber body, said body having a lower section attached to said member and an upper free section, said body having inner -uid pressure responsive areas on the respective upper and lower body sections, reinforcing means in said cup like body responsive to flu'id pressure applied to said pressureresponsive areas, for partially compensating for fluid pressure applied to the respective opposite pressure-responsive areas, said reinforcing means including a plurality of longitudinally extended circumferentially spaced members, said members b eing in the form of wires bent back upon themselves and .forming a base having parallel arms vextending valong s aid core in said lower body section, means constraining the base sections of said arms against movement away from said core, said arms being bent outwardly and divergingfrom said core and thence being bent so as to extend in parallel relation on a plane substantial-ly parallel to said base section, said arms extending into said upper body sections, and means providing a fulcrum for said arms intermediate said upper and lower body sections.

10. A well swab cup comprising: an elongated rigid core adapted to b e carried by a supporting member, said core having molded thereon a cup like rubber body, said body having a lower section attached to said member and an upper free section, said body having inner fluid pressure responsive areas on the respective upper and lower body sections, reinforcing means in said cup like body responsive to fluid pressure appliedto said pressureresponsive areas, for partially compensating for fluid pressure applied t yt herespective `opposite pressure-re-V sponsive areas, Asaid reinforcing means including a plurality oflongitudinally extended circumferentially `spaced members, said members being in the form of wires bent back upon themselves and forming a base having parallel arms ,extendingalong said vcore in said lower bod'ysection,` means constraining Vthe base sections of said arms between -said body sections, and a rigid annular vmember embracing said reinforcing member and disposed in the indentations in said arms, said annular member providing a fulcrum for s'aid arms.

11. A well swab cup comprising an elongated rigid core adapted to becarried by a supporting member, said core Ahaving molded thereon a cup like rubber body, said body having aV lower section attached to said member, a plurality of longitudinally extended reinforcing members in said body, and,means for constraining said reinforcingmembersinsaid lower body section against movement away,from said core, said reinforcing members each being in the form of a wire bent back on itself and having a base extending along said core and embraced bysaid restraining means, said wires havingrarms bent at an angle to said base and diverging from said core, said arms being thence bent so as to extend in` substantially parallelrelation to ,one another longitudinally of said Acup in radially spaced relation to said base.

12. A wire yreinfc'arcing member for a well swab cup, comprising a longitudinally y,extended wire bent back upon itself to ,providea pair of opposed arms, said arms having parallel base sections at one end, and being bent so as to provide portions diverging from said base sections and saidarms having longitudinally extended parallel portions joining'said divergent portions, and located on a plane oiset from the plane of said base sections.

Y 13.' A wire reinforcing member as defined in claim 12, wherein said longitudinally extended arm portions are indented at intermediate points towards the plane of said base sections.

14. A well swab Acomprising a cup-like body of rubber having longitudinally spaced flexible sections adapted to be expanded into engagement with a well conduit, an intermediate inflexible section, and means within said body for imposing on said flexible sections a force tending to resist flexure lthereof as a result of exure of the other Hexible section.

References .Cited `in the tile of thispatent UNITED STATES PATENTS 1,983,523 Crowell Dec. 1l, 1934 2,144,997 Thaheld Jan. 24, 1939 2,581,981 Taylor Jan. 8, 1952 l2,711,939 Losey June 28, 1955