US1983523A - Swab - Google Patents

Description

- Dec. 11, 1934. E. v. CROWELL 1,983523 SWAB Filed June ll, 1929 BY y f* Mmm.

Patented Dec. 11, 1934 UNI-TED STATES PATENT OFFICE SWAB Erd V. Crowell, Los Angeles, Calif.

Application June 11, 1929, Serial No. 370,022

14 claims. (01.103-225) This invention is an improvement in that type of swab disclosed for example in U. S. Patent No. 1,412,213 of April 1l, 1922, wherein the iiuid pressure in a well bore by entering the mouth of y,5 an upwardly opening cup-shaped swabbing element tends to yieldably expand the swab to operative engagement with the wall of the bore.

It is the object of the present invention to provide such a cup-shaped swabbing element having improved means for preventing its distortion or mutilation, while permitting its free radial contraction and expansion for passage through a well bore and swabbing engagement with the wall thereof without excessive wear.

It is a further object of the invention to prevent distortion or mutilation of the swab by a protecting means adapted for cushioning engagement with the wall of the bore so as to eliminate al1 possibility of contact such as might cause excessive wear.

20 It is a still further object of the invention to provide for extreme simplicity of manufacture, with the nished product comprising a durable and substantially integral structure having inherent strength adapting it for the long and hard 25 usage to which swabs are normally subjected.

It is a still further object of the invention to provide a valvular means whereby the bore of the swab is positively opened for passage of fluid by lowering the supporting element of the device with relation to the swabbing element which is frictionally held by its engagement with the wall of the bore, with said valvular means positively closed for trapping the fluid above the same when the supporting element is subsequently elevated for withdrawing the swab.

Further objects of the invention will be readily understood fromA the following description of the accoinponying drawing, in which:

Fig. 1 is a side elevation ofthe swab, partly in axial section and showing the relative position of the parts as the swab is lowered in a well bore.

Fig. 2 is a similar view of one element of the swab, showing the relative position of the parts as the swab is withdrawn from the well bore.

Figs. 3 and 4 are' transverse sections on the lines 3--3 and 4 4 respectively of Fig` 1.

The swab is adapted for use in casing, tubing or other piping in the bore of a well, hereinafter referred to simply as the well bore, and may be run in and withdrawn by suspending the same from drill-pipe, sucker rods, cr any other suitable drill string.

Any desired number of interchangeable swabbing elements may be connected so as to form a swab of any desired length, the embodiment of the invention illustrated at Fig. 1 showing two such swabbing elements, with their connecting mandrel broken away at the line A-A to indicate the possibility of including additional swabbing elements.

The swabbing elements are respectively slidably mounted on mandrels 1 which may be detachably connected by usual pin and box couplings 2 3, with the mandrel of the upper swabbing element having means for suspending the swab from a suitable drill string, the said suspension means shown in the present instance as a threaded pin 4 adapted to. engage a usual string of sucker rods (not shown). A bull plug 5 may be suspended from the mandrel of the lower swabbing element, for example by a threaded bore 3a adapted to receive pin end 2 of the lower mandrel.

The mandrels are preferably each provided with means for limiting upward sliding of the corresponding swabbing element, the said means being shown in the present instance as undercut annular shoulders 6 on the respective mandrels in spaced relation above their lower ends. Valve heads '7 carried by the mandrels preferably cooperate with valve seats in the lower ends of the bores of the swabbing elements, one of said valves being preferably provided at the upper end of the box coupling 3 of each of the intermediate mandrels, and one of said valves being also provided at the upper end of bull plug 5, so that when a plurality of mandrels l are operatively assembled as shown in Fig. 1, one of the valves 7 will cooperate with the corresponding valve seat in the lower end of the respective swabbing elements.

The swabbing elements are `interchangeably slidable on their respective mandrels, and each comprises acup-shaped swabbing element 10 hav- `ing a hollow bore lladapted to loosely receive its corresponding mandrel, with the lower end of bore 11 forming a valve seat 12 adapted for engagement by the corresponding Valve 7, and the upper end of said cup-shaped swabbing element having upwardly extending, axially projecting and circumierentially spaced supporting ngers 13 terminating in a collar 14 which is slidably received on the supporting mandrel. When the swab is lowered in a well bore frictional engagement of the swabbing elements with the wall of the bore will tend to hold the swabbing elements so that the mandrels 1 may be lowered relative thereto for opening valves 7 as shown in Fig. 1, and with the valves in open position the swabbing elements are then lowered in the well along with their mandrels as a result of abutment of the swabbing elements against the corresponding annular shoulders 6. Fluid in the well thus passes through the bores of the swabbing elements and is discharged through the spaces formed between the circumferentially spaced protecting fingers 13; and when the swab is subsequently withdrawn from the well elevation of mandrels 1 with relation to the frictionally held swabbing elements closes valves '7 as shown in Fig. 2, thereby trapping uid above thev swabbing elements through the abutment or" the valves 7 against the lower ends of the respective swabbing elements.

During withdrawal of the swab the pressure of the trapped fluid on the cup-shaped upper ends of the swabbing elements tends to radially eX- pand said elements for fluid tight engagement with the wall of the well bore, and the supporting 'lngers 13 which project upwardly from the swabbing elements prevent excessive distortion of the cup-shaped upper ends of the swabbing elements, and also ward off any obstructions such as might tend to mutilate or cause excessive wear of the swabbing elements. The supporting :lingers are of somewhat flexible, resilient material so as to hold the cup-shaped swabbing elements against collapse while permitting sufficient yielding thereof for avoiding obstructions or irregularities in the well bore, and the flexible fingers are also or" a suitable cushioning material adapted to readily yield without excessive wear when meeting obstructions in the well bore.

As an instance of this arrangement the swabbing element 10 is preferably a hollow sleeve made of rubber of such consistency as to provide a wear-resisting but readily yieldably peripheral contacting surface, and the supporting fingers 13 which project upwardly from sleeve 10 are preferably integral therewith and may be formed of the same rubber, which while readily yieldable is normally shape-retaining so that the fingers provide cushioning retaining means for the upper end of sleevev 10. The collar 14 at the upper ends of 'lingers 13 is preferably also integral therewith and may be formed of the same rubber.

The peripheral wall of sleeve 10 is of appreciable thickness, and the bore of the sleeve preferably flares outwardly at its upper end as shown at 15, so as to form a cup-shaped structure terminating in a relatively sharp peripheral edge 16, and the fingers 13 project upwardly from the relatively thick peripheral wall of the cup, with the outer periphery of the fingers preferably forming an upwardly tapering continuation of the peripheral edge 16 and the inner periphery of the ngers merging into surfacel between its inner and outer peripheries. The fingers `may thus have an appreciable radial thickness without projecting radially outwardly beyond the peripheral edge 16 of the cup, with the side edges of the fingers preferably curving to meet the peripheral edge 16 as shown in Fig. 1, so that the fingers are of sufcient rigidity to prevent excessive distortion of the mouth of the cup-shaped swabbing element, while permitting its free radial expansion responsive to pressure of uid thereon in order that the peripheral contact surface o1" sleeve 10 may maintain a iiuid tight engagement with the wall or" the well bore. As shown in Fig. 2, flaring the mouth 15 of the sleeve 10 and merging the circumferentially spaced fingers 13 into the relatively thick peripheral wall of the sleeve, with the inner periphery of the ingers spaced radially outwardly from the inner periphery of said wall, annularly recesses and weakens the inner periphery of the wall of the cup-shaped sleeve adjacent its mouth; and as a consequence the cup-shaped sleeve is adapted for unito-rm operative expansion without excessive bulging at the base of the cup where the weight of the ioad exerts the greatest expansive force, since the lesser expansive force at the weakened mouth of the sleeve provides substantially the same radial expansion at the mouth of the swabbing element as the greater expansive force at the base of the cup.

A non-yieldable retaining collar 18 of metal or the like, is preferably received on the lower end of sleeve l is of less diameter than that of the upper portion of the sleeve as shown in Fig. 1, so that only that portion of the sleeve above the non-yieldable retaining collar provides a Contact surface adapted for engagement with the wall of the well bore. The lower end of collar 18 is preferably tapered as shown at 19, with the end of sleeve l forming a continuation of said taper and the lower end of the bore 1l of the sleeve oppositely tapering to form the valve seat l2. The collar 13 is securely fixed with relation to sleeve 10, and for this purpose may be provided with radial openings 20 and with an interior shoulder 21 adapted to engage and hold the rubber of which the sleeve is formed.

A guide for mandrel 1 is preferably provided in the bore of sleeve adjacent its lower end, and may form stops adapted for engagement by the shouider 6 of the mandrel for limiting relative axial movement of the swabbing element. For this purpose a bushing 23 having inwardly projecting, circumierentially spaced radial lugs 24 is preferably mounted in bore l1 between the shoulder 6 of the mandrel and they valve seat l2, with said lugs deining a central bore for passage of the mandrel so as to center the same with relation to sleeve 10, but adapted for abutment against shoulder 6 as shown in Fig. 2 in order to limit relative axial movement of the swabbing element. The bushing 23 may be held in place by threading its outer perhipery as shown at 25, so that the rubber of which sleeve 10 is formed will seat in the grooves of the threads.

rihe swabbing element as thus described may be formed in a suitable mold. For this purpose the collar 18 and bushing 23 are placed in a mold which is` adapted to denne the exterior contour of the swabbing element, and a suitable core which is adapted to form the bore of the swabbing element and its spaced supporting ngers 13 and collar 14, is also placed in the mold. 'Ihe spaces between the lugs 24 of bushing 23 may be lled with molding sand. The prepared mold is then filled with plastic rubber which is suitably vulcanized so that the rubber is securely molded to bushing 23 and to collar 18, and by then stripping the molded article from its mold and removing the sand from between the lugs 24, a substantially integral swabbing element is formed which provides a yieldable cup-shaped swab having supporting lingers for preventing distortion 0r mutilation oi the cup, with said fingers formed of a cushioning material adapted to readily yield when meeting an obstruction.

1 claim: I,

l. In a swab, an integral molded' structure of resiliently iieXible cushioning material comprising a cup with supporting ngers projecting upwardly therefrom and a collar of the same material connecting the upper ends of the supporting lingers.

2. A swabbing element comprising flexible material molded to form a sleeve having one end embedded in a retaining annulus and its opposite end forming a cup having supporting ngers projecting upwardly therefrom in circumferentially spaced relation and terminating in a collar of reduced diameter.

3. In a swab, a swabbing element comprising flexible material molded to form a hollow sleeve having one end embedded in a retaining annulus with a bushing having inwardly projecting circumferentially spaced guide lugs embedded in the bore of said end of the sleeve, the opposite end of the molded sleeve forming a cup having supporting iingers projecting upwardly therefrom in circumferentially spaced relation and terminating in a collar of reduced diameter, and a mandrel in the bore of the sleeve centered in the bushing by the guide lugs.

4. In a swab, an integral structure of flexible material comprising a cup with supporting fingers projecting upwardly therefrom and terminating in an annular collar.

5. In a swab, an integral structure of flexible material comprising a cup with supporting ngers projecting upwardly from the outer peripheral portion of the cup in circumferentially spaced relation and terminating in an annular collar.

6. In a swab, an integral structure of flexible material comprising a cup with supporting ngers projecting upwardly from the outer peripheral portion of the cup in circumferentially spaced relation and convergently inclined toward their upper ends and terminating in an annular collar.

7. In a swab, an integral structure of flexible material comprising a cup with supporting ngers projecting upwardly from the outer peripheral portion of the cup in circumierentially spaced relation with the sides of next adjacent fingers curving to meet the outer periphery of the cup and the fingers terminating in an annular collar.

8. In a swab, an integral structure of flexible material having a hollow bore and comprising a cup with supporting lingers projecting upwardly therefrom and terminating in an annular collar, guide lugs projecting into the hollow bore, and a supporting mandrel centered in the hollow bore by the guide lugs.

9. In a swab, an integral structure of flexible material comprising a cup with supporting 1ingers projecting upwardly therefrom and terminating in an annular collar, the integral structure having an open bore, and a valve seat at the lower end of the open bore.

10. In a swab, an integral structure of flexible material comprising a cup with supporting iingers projecting upwardly therefrom and termi nating in an annular collar, the integral structure having an open bore, and the flexible material forming a cushioning Valve seat at the lower end of the bore.

11. In a swab, an integral molded structure comprising a cup with supporting ngers projecting upwardly therefrom and terminating in an annular collar, and an annulus recessed to receive the molded structure for securing the annulus relative to the molded structure.

12. In a swab, an integral structure of iiexible material comprising a cup with supporting fingers projecting upwardly therefrom and terminating in an annular collar, the cup being adapted for expansion by pressure exerted downwardly into the cup, and the cup being substantially weakened below the lingers and adjacent its mouth.

13. In a swab, an integral structure of flexible material comprising a cup with supporting ngers projecting upwardly therefrom and terminating in an annular collar, the cup being adapted for expansion by pressure exerted downwardly into the cup, and the cup being annularly recessed below the ngers and adjacent its mouth.

14. In a swab, an integral structure of iiexible material comprising a cup having a peripheral wall of appreciable thickness and fingers projecting upwardly from said peripheral wall, the peripheral wall being tapered at its upper end so as to form a flaring mouth for the cup, and the fingers being of appreciable radial thickness but having their inner periphery spaced radially outwardly from the inner periphery of said ilaring mouth and their outer periphery forming a continuation of the outer periphery of said mouth.

ERD V. CROWELL.

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