US3023062A

US3023062A - Swab rubber unit for well swab

Info

Publication number: US3023062A
Application number: US107845A
Authority: US
Inventors: Thomas C Waldrop
Original assignee: Empire Rubber Co
Current assignee: Empire Rubber Co
Priority date: 1961-05-04
Filing date: 1961-05-04
Publication date: 1962-02-27
Anticipated expiration: 1979-02-27

Description

T. C. WALDROP SWAB RUBBER UNIT FOR WELL SWAB Filed May 4, 1961 Elli/Illa" THOMAS C. WALDROP INVENTOR- WQQW A TTOR/VEY Feb. 27, 1962 sa a! Wilda/ill m United States This invention relates to a well swab adapted to be lowered in a well pipe or tubing on a wire line and to elevate well fluids in the pipe or tubing upon raising the swab therein, and it concerns more particularly a swab rubber unit for such a swab as hereinafter described.

The swab rubber unit of this invention is an improve ment over the swab rubber units for well swabs of the type generally as shown and described in Patent No. 2,633,808, April 7, 1953, issued to Jack C. Webber.

The Webber patent above referred to shows, FIGS. 1 to 4, a well swab having a swab rubber unit which is molded of resilient material, such as rubber, and has a plurality of longitudinally spaced inverted frusto-conical, radially outwardly and upwardly inclined flexible annular rib-like sealing rings or cups formed on a central tubular core which, as shown, is bonded directly to a mandrel forming a structural part of the swab, but which in practice may be also formed on a separate sleeve receivable on such a mandrel whereby the swab rubber unit, together with the sleeve, is expendable.

An advantageous feature of the swab rubber unit shown in the Webber patent, as compared to swab rubber units previously employed having large wire reinforced single cups designed to carry the entire load of fluids being displaced from a well pipe or tubing, and which are characterized by their inflexibility, is that the swab rubber unit shown in the patent, because of its flexibility, is less likely to be damaged upon impact with fixed objects which may obstruct its free movement through the well pipe or tubing.

Another advantageous feature of the arrangement shown in the patent is that the rib-like sealing rings or cups, which are of slightly less diameter than the well pipe or tubing but are normally inclined radially outwardly and upwardly, whereby the swab may be readily lowered in a well pipe or tubing, are each designed to resist predetermined pressure differentials on opposite sides thereof, so that each carries its proportionate share of the load of a column of fluid in the well pipe or tubing.

The sealing rings described in the Webber patent are designed to occupy, during various phases of operational loading, all of the following positions:

(1) A position at rest in which the sealing rings are not in contact with the tubing wall,

(2) A position caused by intermediate or optimum loading, in which the sealing rings are deflected downwardly and outwardly to contact the tubing wall and are substantially perpendicular to the tubing wall,

(3) A position caused by loading in excess of the design capacity ef the sealing rings, in which they are flexed downwardly from the position (2) described above.

An object of this invention is to provide an improved swab rubber unit having incorporated therein all of'the advantages and safety of the arrangement taught by Webber, while at the same time being characterized by its substantially greater lifting capacity.

This invention contemplates a swab rubber unit in which a series of radially outwardly extending annular ribs, of smaller diameter than the rib-like sealing rings or cups, are formed on the central tubular core, immediately below the sealing rings or cups, respectively, for abutment against the under sides of the sealing rings or cups to resist downward flexing movement thereof, whereby the sealing rings or cups are reinforced or 4 atent snzaosz Patented Feb- 27, 1962 comprises a metal sleeve having the flexible sealing rings.

or cups molded thereon and having the annular reinforcing or back up ribs below the respective sealing rings or cups, which in the form shown are rigid, formed integrally therewith.

This application relates to three other forms of the invention in which the central tubular core as well as the flexible sealing rings or cups and the annular reinforcing or back up ribs below them are of molded rubber construction, or some other yieldable semi-rigid material.

The invention will be readily understood by referring to the following description and the accompanying drawing, in which:

FIGS. 1 and 2 are elevational views, partly in section taken on a median line, showing fragmentarily a swab operatively positioned in a well pipe or tubing, the swab including a mandrel having a swab rubber unit of the type shown in the Webber patent above referred to (FIGS. 1 to 4) received thereon. FIG. 1 shows the flexible sealing rings or cups at rest, while FIG. 2 shows them in' the overloaded position.

FIG. 3 is an elevational view, partly in section taken on a median line, showing a swab operatively positioned in a well pipe or tubing, the swab including a mandrel having a swab rubber unit embodying this invention received thereon, and showing the flexible sealing rings or cups, which are in position to be reinforced or backed up by the annular ribs below them, at rest.

FIG. 4 is an elevational view, partly in section taken on a median line, showing fragmentarily the apparatus illustrated in FIG. 3, and showing the flexible sealing rings or cups in loaded positions.

FIGS. 5 and 6 are elevational views, partly in section t"ken on a median line, showing fragmentarily a swab operatively positioned in a well pipe or tubing, including another form of swab rubber unit embodying this invention. FIG. 5 shows the flexible sealing rings. or cups, which are reinforced or backed up by the annular ribs below them, at rest, while FIG. 6 shows them in loaded positions. v

FIGS. 7 and 8 are views similar to FIGS. 5 and 6, respectively, showing fragmentarily a swab operatively positioned in a well pipe or tubing, including another form of swab rubber unit embodying this invention. FIG. 7 shows the flexible sealing rings 01 cups, which are reinforced or backed up by the annular ribs below them, at rest, while FIG. 8 shows them in loaded positions.

Referring to FIG. 3 of the drawing, the numeral 1 designates generally a well swab which is similar to the swab shown in the Webber patent (FIGS. 1 to 4), and which is operatively positioned but under no load in a well pipe or tubing, indicated by the numeral 2.

The swab 1 includes a tubular mandrel 3 having swab rubber units embodying this invention, as hereinafter described, three of which are shown, each designated generally by the numeral 4, received thereon. p

A valve cage 5 having a ball valve 6 therein is secured to the upper end of the mandrel 3, and a wire rope socket 7, shown fragmentarily, is secured to the upper end of the valve cage 5. The ball valve 6, which serves as a check valve, is adapted to be seated in the upper end of the mandrel 3 upon upward movement of the swab 1 in the well pipe or tubing 2.

As shown in FIGS. 1 and 2, the mandrel 3 has a swab rubber unit, designated generally by the numeral 8, which corresponds to the swab rubber units 4 shown in FIGS. 3 and 4, received thereon. The swab rubber unit 8 is of the type shown in the Webber patent, as above described, and includes a central tubular core 9 having a plurality of longitudinally spaced flexible, radially outwardly and upwardly inclined rib-like sealing rings or cups 11) formed thereon.

In their at rest positions, as shown in FIG. 1, the flexible sealing rings or cups 10 have a diameter slightly less than the diameter of the well pipe or tubing 2.

i The swab rubber units 4 shown in FIGS. 3 and 4 each include a central tubular core 11, corresponding to the central tubular core 9 shown in FIGS. 1 and 2, having a plurality of longitudinally spaced flexible, radially outwardly and upwardly inclined rib-like sealing rings or cups 12, corresponding to the sealing rings or cups 10 shown in FIGS. 1 and 2, formed thereon.

. A series of radially outwardly extending annular ribs 13, of smaller diameter than the flexible sealing rings or cups 12, are formed on the central tubular core 11, immediately below the sealing rings or cups 12, respectively, for abutment upon by the under sides of the sealing rings or cups 12 when under load to resist further downward flexing movement thereof, whereby the sealing rings or cups 12 are reinforced or backed up by the annular ribs 13 below them and are thereby adapted to lift greater loads upon upward movement of the swab 1 in the well pipe or tubing 2.

The portions of the flexible sealing rings or cups 12 which extend radially outwardly beyond the support of annular ribs 13, being relatively short, are characterized by their relative stiffness whereby they resist downward flexing.

The central tublar core 11 as well as the flexible sealing rings or cups 12 and the annular reinforcing or back up ribs 13 below them, like the central tubular core 9 and the flexible sealing rings or cups 10 shown in FIGS. 1 and 2, are formed of resilient or semi-resilient material such as rubber, but the several components may or may not be of the same material.

The annular reinforcing or back up rib 13 shown in FIGS. 3 and 4 are built up or thickened on their under sides whereby they resist being flexed downwardly, and because of their smaller diameter they do not frictionally engage the well pipe or tubing 2 upon moving the swab 1 upwardly therein.

FIGS. and 6 show an arrangement similar to the arrangement shown in FIGS. 3 and 4 in which the annular reinforcing or back up ribs 13, which are only slightly thicker than the corresponding flexible sealing rings or cups 12, are characterized by upper faces which are arranged parallel to the under sides of the corresponding flexible sealing rings or cups 12, and are separated therefrom only by circumferential slits, so that while the annular reinforcing or back up rigs 13 are adapted to resist downward flexing of the flexible sealing rings or cups 12, the sealing rings or cups 12 and the annular reinforcing or back up ribs 13 are adapted to be flexed downwardly together upon the application of a predetermined excess pressure differential to opposite sides thereof, as in moving the swab 1 upwardly in the well pipe or tubing 2.

FIGS. 7 and 8 show an arrangement similar to the arrangement shown in FIGS. 5 and 6 in which the annular reinforcing or back up ribs 13 are relatively thicker and are separated from the under sides of the corresponding flexible sealing rings or cups 12 by relatively wider circumferential slots.

In all forms shown the back up ribs are smaller in diameter than the inner diameter of the well tubing, while the sealing rings or cups are of substantially the same diameter as the inner diameter of the well tubing. Swab cups embodying this arrangement are characterized by desirable free movement downward, both through the fluid column and past projecting obstructions in the well pipe, since the sealing lips can be easily flexed upwardly and the back up ribs are recessed relative to the inner well pipe wall. However, on the up-stroke when the cup is under load, the sealing rings flex downwardly into abutment with their respective back up ribs, which combination affords a relatively much greater resistance to downward flexing, resulting in a larger load lifting capability.

The invention may be modified in various ways without departing from the spirit and scope thereof.

1 claim:

1. In a swab rubber unit for a well swab, the combination of a central tubular core having a plurality of longitudinally spaced, flexible rib-like sealing rings or cups formed thereon and inclined radially outwardly and upwardly therefrom, the flexible sealing rings or cups having a diameter in their at rest position corresponding substantially to the diameter of a well pipe or tubing, and a series .of radially outwardly extending annular ribs, of smaller diameter than the flexible sealings rings or cups, formed on the central tubular core, immediately below the sealing rings or cups, respectively, for abutment against the under sides of the sealing rings or cups to resist downward flexing movement thereof, whereby the sealing rings or cups are reinforced or backed up by the annular ribs below them and are thereby adapted to lift greater loads upon upward movement thereof in the well pipe or tubing.

2. In a swab rubber unit for a Well swab, the combination of a central tubular core having a plurality of longitudinally spaced, flexible rib-like sealing rings or cups formed thereon and inclined radially outwardly and upwardly therefrom, the flexible sealings rings or cups having a diameter in their at rest positions corresponding substantially to the diameter of a well pipe or tubing, and a series of radially outwardly extending annular ribs, of smaller diameter than the well pipe or tubing, formed on the central tubular core, immediately below the sealing rings or cups, respectively, for abutment against the under sides of the sealing rings or cups to resist downward flexing movement thereof, the central tubular core, the flexible sealing rings or cups, and the annular ribs being formed of molded resilient material.

3. The structure of claim 2, the annular ribs being characterized by planar upper faces which extend radially outwardly from the central tubular core, perpendicular to 1 its longitudinal axis, and as viewed in sectional elevation,

intersect the under sides of the corresponding flexible sealing rings or cups at acute angles, the annular ribs being built up or thickened on their under sides whereby they resist being flexed downwardly.

4. The structure of claim 2, the annular ribs being characterized by upper faces which are arranged parallel to the under sides of the corresponding flexible sealing rings or cups, the "annular ribs having a thickness approaching the thickness of the flexible sealing rings or cups, and being closely spaced relative thereto, so that while the annular ribs are adapted to resist downward flexing of the flexible sealing rings or cups, the sealing rings or cups and the annular ribs are adapted to be flexed downwardly together upon the application of a predetermined pressure differential to opposite sides thereof.

No references cited.