US3266384A

US3266384A - Well swab assembly

Info

Publication number: US3266384A
Application number: US154528A
Authority: US
Inventors: Scaramucci Domer
Original assignee: Individual
Current assignee: Individual
Priority date: 1961-11-24
Filing date: 1961-11-24
Publication date: 1966-08-16
Anticipated expiration: 1983-08-16

Description

Aug. 16, 1966 D. SCARAMUCCI WELL SWAB ASSEMBLY 5 Sheets-Sheet 1 Filed NOV. 24 1961 INVENTOR Dmwae 564 A MUCC/ 6, 1966 D. SCARAMUCCI WELL SWAB ASSEMBLY 5 Sheets-Sheet 2 Filed Nov. 24, 1961 F15- .14 Fizz-J5 INVENTOR. a 00/145 56% EAMUC'C/ 1956 D. SCARAMUCCI WELL SWAB ASSEMBLY 5 Sheets-Sheet 3 Filed NOV. 24, 1961 ill m i -w. 1 I Hi gi a INVENTOR. .2 i .L E.- .1 Z 2 .1 E.- .15 DOME-2 ficnenmucaf United States Patent 3,266,384 WELL SWAB ASSEMBLY Domer Scaramucci, R0. Box 9125, Oklahoma City 15, Okla. Filed Nov. 24, 1961, Ser. No. 154,528 21 Claims. (Cl. 92-192) This invention relates to a swab device for moving a fluid or semiitluid substance through a tubular passageway. More particularly, but not by way of limitation, the present invention relates to a device for swabbing liquid, and to a lesser extent solid particulate materials, from the interior of a tubing string of the type employed in oil wells.

in instances where the reservoir pressure surrounding an oil well has dropped to a degree such that the natural flow of oil from the well is substantially decreased, or is altogether stopped, one of the methods frequently used to induce further flow for some time without the necessity of pumping is the agitation of the fluid standing in the well by swabbing action. Such swabbing action is accomplished by dropping a well swab to the bottom of the production tubing on a wire line. As the swab is lowered through the liquid in the production tubing, the construction of the swab allows the liquid to pass upwardly around or through the swab. On withdrawing the swab from the well, all liquid above the swab is lifted thereby up the tubing and out of the well. By removing part of the fluid column in the well bore, the bottom hole pressure is reduced and more oil and gas will flow rapidly int-o the bore from the surrounding well cavity, thus imparting upward momentum to the entire column of liquid. The suction effect developed by the swab also causes the gas in solution in the oil to be released, thus reducing the average density of the column of fluid and further permitting flow. Once flow is started in this way, it will often continue for some time without additional artificial assistance.

Well swabbing of the type described also performs other useful functions, such as the removal of quantities of paraffin which collect in the production tubing and restrict the flow of fluid therethrough -so that the well is not produced at the optimum rate. Additionally, such well swabs are often used to remove drilling fluids from a bore hole following completion of drilling operations and before bringing the well into production.

Generally, a well swab assembly of the type employed for such swabbing operations includes a mandrel which is adapted to be suspended from a wire line. The mandrel has a fluid passageway therethrough to permit fluid to pass through the mandrel as it is lowered in the production tubing on the wire line, and a sleeve is slidingly positioned around the mandrel to seal this passageway when it is slid down the mandrel toward the lower end thereof and to open the passageway when it is slid in the opposite direction. A plurality of resilient sealing elements or lips are bonded to the outer periphery of the sleeve and function to seal off the production tubing as the swab assembly is drawn upwardly in the tubing. The resilient sealing elements are perhaps the most important element of the Well swab assembly in the sense that they are subjected to rather extreme physical conditions in the operation of the swab, and yet must continue to function properly under all such conditions if the swabbing technique is to be effective to accomplish its intended ends.

The resilient sealing elements must be sufficiently flexible in one direction so that they offer little or no resistance to the gravitation of the swab assembly down into the production tubing.

On the other hand, a sufficient strength must characterize the sealing elements to permit them to carry a Patented August 16, 1966 very large fluid load to the surface upon withdrawal of the swab from the well. While carrying such fluid loads, the sealing elements must maintain an effective seal against the internal walls of the production tubing to prevent leakage of the fluid around the swab assembly. Thus, the design of such Well swab assembly sealing element entails the solution of two problems requiring seemingly opposite solutions. First, the sealing elements must be suf'ficiently flexible to offer a minimum of resistance to the downward movement of the swab assembly in the well tubing, and to be easily biased into sealing contact with the walls of the tubing when the swab is withdrawn from the well. Secondar-ily, but of equal importance, sufficient rigidity or stiffness must characterize such sealing elements to permit them to lift the enormous fluid loads as required.

Further difficulty is presented to the effective functioning of the resilient elements of the swab assembly by the manner in which the production tubing is made up or installed in the well. In the first place, the diametric dimension of the tubing varies over the length of the string. Also the tubing strings generally do not make up concentrically at the couplings between tubing sections. Egg-shaping or distortion from circular cross-section at numerous points in the string is common. Moreover, corrosion deposits and accumulations of scale and foreign matter develop on the inside Walls of the tubing. All of these factors result in a very substantial increase in the wear to which the resilient sealing elements of the well swab assembly are subjected as they contact the tubing during the upward movement of the swab in the well. -In fact, with the progressive increase in the depth of oil wells, it has become increasingly difficult to make the trip from the bottom of the well to the surface without fully wearing out the resilient sealing members. Even when such complete destruction dose not occur, a substantial decrease in the volume of lifted fluid is sustained due to leakage around the sealing elements.

The most serious problem posed by the makeup of the tubing string, insofar as such makeup effects efficient well swabbing, is that which is posed by the recesses, or bore enlargements which occur at each casing coupling. Usually the inside diameter of each coupling is equivalent to the outside diameter of the externally threaded tubing sections, and the length of the couplings is such that a gap of up to about one inch remains between the ends of adjacent tubing sections. Although the ends of the tubing sections usually have an inner bevel, it is usually rough and lacks concentricity, so that the resilient sealing elements of the well swab assembly are not only subjected to severe wear at this point, but also cannot effectively seal against the irregular tubing walls. Some 30 to 35 couplings are included for every 1,000 fee-t of well string. Therefore, several hundred coupling gaps must be traversed by the sealing elements during each trip from the bottom of the well to the surface.

That no well swab assembly which has been conceived to date satisfactorily solves the many problems discussed above is evidenced by the volumes of material which have been published on the subject and the large number of patents which have heretofore been issued upon swab cups and well swab assemblies. In one type of well swab assembly, the sleeve which is slidingly fitted around the mandrel and its associated resilient sealing member is referred to as a swab cup. (This term is also sometimes applied with less appropriateness of description to other types of well swab assemblies.) In such cup-type swab assemblies, a long, upstanding lip of resilient material is secured to a metal sleeve which is slidingly fitted around the mandrel, and the lip defines with the sleeve a deep pocket or groove which is open at the top to fluid loading. The long, upstanding lips of such cups are made of sufficient length to permit them to traverse the gap between the ends of coupled tubing sections so that loss of sealing engagement of the lip with the walls of the tubing is avoided, as is the by-passing of fluid around the lip.

An annular, radially extending heel or base ring is secured to the lower end of the metal sleeve and supports the resilient sealing lip structure so as to lessen the tendency to extrude the resilient material past the sleeve under conditions of heavy loading. Ordinarily, the resilient lip is constructed of rubber or some similar material.

The upstanding lip type of swab cup is made in two styles. In one of these styles, the lip is reinforced by a plurality of reinforcing wires which extend from one end of the lip to the other at the outer peripheral surface thereof. In the other style, no wire reinforcement is utilized.

The unreinforced, upstanding lip type of swab cup is utilized in swabbing situations where relatively light loading is anticipated, such as in shallow wells. This is because the non-reinforced type is more flexible and pliant than the cup provided with the described reinforcing wires, and is somewhat more eflicient for lifting fluid, provided that the load carried does not exceed the supporting ability of the upstanding lip. For swabbing applications involving heavier loading, the wire-reinforced cup is employed. However, having greater rigidity and flexibility, this type of cup requires considerably heavier loading in order to flex or actuate the lip structure into tight sealing engagement with the tubing walls, thus usually permitting some fluid to bypass the swab cup at the beginning of the upward movement of the swab in the well. Since the Wire-reinforced cup is fairly rigid, the upstanding lip structure must be molded undersizethat is, of lesser diameter than the smallest diameter encountered in the tubing string. This is in order that it will not bear against the walls of the tubing, or if so, only lightly so as to permit the well swab assembly to fail freely to the bottom of the tubing. The heel or bottom portion of the swab cup must be even more undersized, since it has very little tendency to contract and pass irregularities in the tubing. Contraction or compression of this heel portion is yet more limited by the anchorage of the reinforcing wires therein, which anchorage makes the heel structure quite rigid.

Although the wire-reinforced, upstanding lip type of swab cup is recognized as the most popular now in use and has the greatest load-carrying capacity of all such cups, it presents certain serious disadvantages in operation and additionally entails a high cost of manufacture. On the other hand, as previously explained, the plain or non-reinforced type of cup is more eflicient for lighter loads and is cheaper to make. However, it is less durable and is limited in its lifting capacity.

One of the major disadvantages of the wire-reinforced type of swab cup is the propensity of such cups to deposit bits of metal and rubber in the tubing string due to the shearing off of the reinforcing wires and the upstanding lips after the cups have been subjected to the great wear involved in passing a number of the coupling gaps hereinbefore described. This shearing off results from the bulging outwardly of the upstanding lip by the pressure acting outwardly thereon each time the lip bridges across the gap formed between the ends of the tubing sections where they are connected by the couplings. This condition of bulging at the coupling gaps causes rapid wear and loss of sealing efficiency. Moreover if the cup is overloaded, complete destruction of the plain rubber version can be expected. The wire type on the other hand will withstand greater abuse early in its wear life, but as the wires are constantly in metal-to-metal frictional contact with the tubing walls, wear is rapid near the mid-point of the wires, creating a substantial reduction in their cross-sectional area. Thus, in average operation, after two or three trips from the bottom of the well to the surface, the cups must be replaced, even though they are still scaling, in order to avoid the loss of some of the wire elements into the tubing string. Such loss of the wires into the tubing string necessitates an expensive clean-out operation and frequently even requires the complete pulling of the tubing string and the re-running thereof.

Additionally, with wells currently being drilled deeper and with the new and expanding use of plastic for coating well tubing Walls, the use of the wire-reinforced swab cups has presented the new problem of avoiding the scoring and damaging of such plastic coating by frictional contact therewith of the wire-reinforcing elements. As a result, the use of such wire-reinforced swab cups in plastic-coated tubing strings has constantly decreased, and the employment of those types of swab assemblies in which the resilient sealing elements contain no wires has constantly increased. This increase has been realized in spite of the fact that only limited loads can be handled per trip with the plain or non-reinforced sealing elements, therefore requiring considerably more time and expense to swab the well than when the wire-reinforced type of cups are employed.

Among the more recent efforts to provide an effective swab cup without resort to wire-reinforcing elements can be cited the general type of swab cups disclosed in Webber U.S. Patent 2,633,808, Taylor U.S. Patent 2,802,535, and Webber U.S. Patent 2,975,722. The swab cups of the cited type generally comprise a rubber sleeve which is bonded around the conventional sliding metallic sleeve carried by the swab assembly mandrel and having a plurality of radially extending lip members spaced along the length of the rubber sleeve. These lip members are generally quite flexible so that they are able to flip over from a position in which they point slightly upwardly in the tubing string to a load-carrying position in which they are inclined slightly downwardly in the string and contact the interior walls of the string at their outer ends. The several lip members are not of sufliciently large diameter to bridge radially across the coupling gaps. Sealing across such coupling gaps is effected by providing enough of the lip members so that some of the lip members are sealing against the walls of the tubing string both above and below the couplings, even though the lip members in the middle do not extend into contact with the coupling per se.

If the lip members in the multiple lip type of swab cup are made sufficiently thin and flexible, they may be flipped over or inverted a number of times in passing up and down the tubing string without serious danger of rupturing at their base or hinge point where they are connected to the sleeve of resilient material. On the other hand, if the lip members are made sufliciently thin and flexible to avoid such fracturing, they are very inefficient and can only be used to lift very light fluid loads. In general, this type of swab cup will load to only about one-third of the capacity of the wire-reinforced type.

In order to improve the load-carrying capacity of the multiple lip-type swab cup, cups having lips which are thicker, particularly at the base thereof, and relatively less flexible have been employed. These cups, though having the ability to lift considerably heavier fluid loads, do not withstand the wear to which they are subjected in passing through the tubing string as well as the more flexible thin lips previously described. They also present the great disadvantage of rupturing along their hinge point relatively early during their operating life.

From the foregoing description of the problems encountered in well swabbing and of the failures of the leading types of previously developed swab cups to adequately solve all of these problems, it is apparent that a very real need exists in the art for the development of a swab cup of radical new design which will successfully overcome the problems discussed in a manner not heretofore effectively accomplished. The present invention presents a novel cocncept in well swab assembly construction, and I have found that well swab assemblies constructed in accordance with the invention eifectively meet the need for a plain rubber cup having no exposed wire-reinforcing members in association therewith. Yet my well swab assembly possesses a load-carrying capacity equivalent to, or greater than, the load-carrying capacity of the wire-reinforced types of swab cups heretofore in use. Moreover, the well swab assembly in the present invention has been definitely proven to have greater wear resistance and to greatly outlast the types of such devices previously in use. p

In its basic design, a preferred embodiment of the invention comprises the usual metallic sleeve or cylindrical member which is slidingly mounted on the mandrel, an annular sleeve of resilient material around the metal cylindrical member and bonded thereto, and an annular, flexible lip of resilient material formed integrally with the sleeve of resilient material adjacent one end thereof and extending radially outwardly therefrom toward the internal walls of the tubing. The annular sleeve of resilient material has a thick, load-carrying portion which is of lesser diameter than the minimum internal diameter encountered in the tubing string. This thick, load-carrying portion extends from one end of the metal cylindrical member over a major portion of the length thereof. The sleeve of resilient material further has a lip-supporting portion which is contiguous to, and formed integrally with, the load-carrying portion thereof, and which extends from the load-carrying portion to the opposite end of the metal cylindrical member. The lip-supporting portion of the resilient sleeve is of lesser radial thickness than the load-carrying portion and is the portion of the resilient sleeve which carries an annular flexible lip which extends radially outward from the sleeve.

The flexible lip has an outside diameter such that when the lip is positioned in a plane extending normal to the axis of the well tubing, the lip will establish contact with the internal walls of the tubing sections 12. I11 the basic design of the assembly, the lip occupies this plane in its relaxed, unstressed state. In certain modified forms of the invention, the flexible lip extends uwardly at an angle to the axis of the tubing and does not contact the walls of the tubing until the lip is biased into said plane by the impress of the fluid load above the swab assembly. The spacing of the flexible lip from the loadcarrying portion of the sleeve is such that when the well swab assembly is fully loaded hydrostatically, the lip will be biased into sealing engagement with the tubing walls and will simultaneously be placed in abutting contact with the load-carrying portion of the resilient sleeve.

In the operation of the well swab assembly, the flexible lip offers little or no resistance to the downward fall of the swab in the tubing string. As the swab assembly is pulled upwardly in the string, however, the flexible lip is biased downwardly and outwardly into sealing engagement with the tubing walls by the fluid load above the assembly. Simultaneously, the lip comes to rest upon, and along with the load, is supported by the load-carrying portion of the resilient sleeve. This thick loadcarrying portion of the resilient sleeve thus reinforces and supports the lip and prevents the development of excessive shear forces across the hinge line of the lip. An extremely heavy fluid load can be carried by the swab cup assembly without fluid leakage, and yet the thin lip is characterized by suflicient flexibility to allow it to conform to irregularities in the tubing string as they occur.

In order to maintain the fluid seal as the well swab assembly passes the couplings in the tubing string, it is preferable to employ a plurality of the swab units disposed in axial juxtaposition along the length of the mandrel, or alternatively, to provide a substantially longer resilient sleeve having a plurality of load-carrying portions, lip-supporting portions, and lips tormed thereon in the relation to each other hereinbefore specified.

When the well swab assemblies of the invention are constructed in this manner, the flexible lips are provided in suflicient number to permit the assembly to bridge across the gaps occurring at the tubing couplings with at least one of the lips in sealing contact with the tubing walls above or below the gap.

From the foregoing discussion, it will be perceived that \it is a major object of the present invention to provide a relatively inexpensive, yet eflicient and durable well swab assembly for removing liquid and solid particulate matter from the interior of a string of oil well tubing.

An additional object of the present invention is to provide a well swab assembly which presents only nonmetallic material tor contact with the internal walls of the well tubing, and yet which is capable of supporting a relatively large fluid load.

An additional object of the present invention is to provide a well swab assembly which is not subjected to destructive wear in passing through the well tubing to the extent that has been characteristic of previous types of swab assemblies.

An additional object of the invention is to provide a well swab assembly which is constructed to avoid the subjection of the flexible sealing lips of the assembly to forces tending to shear off or rupture the lips as the assembly passes by the gaps formed by the couplings of the tubing string.

Another object of the invention is to provide a well swab assembly which is positive in its action and yet which may readily pass by obstructions normally encountered in the well tubing in which it operates.

A further object of the invention is to provide a well swab assembly which may be utilized effectively to raise either light or heavy fluid loads from oil wells of varying depths.

A further object of the invention is to provide a well swab assembly in which there is no cup-shaped expansible sealing member which provides a cup in which sand or other matter may accumulate so as to interfere with the proper functioning of the swab assembly.

In addition to the hereinbefore described objects and advantages of the present invention, other objects and advantages of the invention, including several modified embodiments thereof, will become apparent and will be better understood tfirorn a reading of the following disclosure in conjunction with a perusal of the accompanying drawings which illustrate my invention and certain types of prior art well swab assemblies.

In the drawings:

FIGURE 1 is a vertical sectional view through the center of a well swab assembly of the wire-reinforced type previously used and through a tubing string in which the swab assembly is located. The mandrel of the assembly is illustrated in elevation.

'FIGURE 2'is a vew similar to FIGURE 1, but showing a different type of well swab assembly which has previously been utilized.

FIGURES 3 through 8 show vertical sectional views through several embodiments of the present invention. The basic embodiment of the invention is illustrated in FIGURE 3.

-In FIGURES 9 through 13, the basic embodiment of FIGURE 3 is illustrated in section, as is the mandrel upon which it is mounted. 'In FIGURE 9, the well swab assembly is being lowered into the tubing string. In FIGURE 10, the swab assembly is shown in the position it assumes as it first commences to ascend the tubing string upon being pulled 'out of the well. FIGURE 11 shows the swab assembly as it appears when fully loaded during its upward movement. FIGURE 12 illustrates the position assumed by the flexible sealing lip as the swab assembly moves upwardly past a coupling gap in the tubing string. FIGURE 13 illustrates the position assumed by the flexible sealing lip and the loadcarrying portion of the resilient sleeve of the assembly "Z immediately following the traverse of the coupling gap by the lip and the re-establishment of the fluid seal.

lF-IGURES 14 and 15 are sectional views illustrating the manner in which the modified embodiment of the invention illustrated in FIGURE is utilized for lifting fluid in the tubing string.

FIGURES 16 and 17 are sectional views illustrating the operation of the modified embodiment shown in FIG- URE 7 of the drawings. In FIGURE 16, the well swab assembly is being lowered into the tubing string, while in FIGURE 17, the swab assembly is being withdrawn from the string.

Referring now to the drawings in detail, and particularly to FIGURE 1, a tubing string designated generally by reference character 10 comprises a plurality of tubing sections 12 which are interconnected by a coupling 14. A gap 16 of approximately one inch or less exists between the opposed ends of the tubing sections 12 and due to the greater diameter of the coupling 14 than each of the tubing sections, the inside diameter of the string 10 is enlarged at the coupling.

In FIGURE 1, a well swab assembly of the upstanding lip, wire-reinforced, cup type is illustrated. A well swab assembly of this type comprises a cylindrical mandrel 1 8 having a retaining flange 20 at the lower end thereof and a cup-type swab, designated generally by reference character 22, carried upon the mandrel. The cup-type swab comprises a metallic cylindrical sleeve 24 which is slidingly mounted upon the mandrel 18 for reciprocation axially upon the mandrel as the swab assembly is moved up and down in the tubing string. The metallic cylindrical sleeve 24 carries a rubber cup 26 which includes a thick heel or base portion 28 and an upstanding lip 30. The upstanding lip 30 is normally spaced apart from the metallic cylindrical sleeve 24 so that a groove or pocket 32 is defined between the upstanding lip and the metallic cylindrical sleeve. The dimensions of the upstanding lip 30 are such that the lip will span or traverse the gap 16 between tubing sections 12 at the coupling 14.

In the cup-type swab assembly illustrated in FIGURE 1, a plurality of reinforcing wires 34 are provided around the outer periphery of the upstanding lip 34) and are embedded in the base portion 28 of the rubber cup.

In operation, as the cup-type swab assembly 22 is pulled upwardly in the tubing string 11 the hydrostatic forces exterted by the fluid head above the assembly cause the upstanding lip 30 to bellow out into sealing engagement with the internal walls of the tubing. It will be apparent that at this time the reinforcing wires 34 bear against the internal walls of the tubing and thus undergo considerable frictional wear. The walls of the tubing also are scored by the wires 34 as the swab assembly is moved upwardly.

The greatest disadvantage, however, of the wire-reinforced swab assemblies occurs as a result of the stresses which act upon the upstanding lip 30 and their reinforcing wires 34 as the swab assembly passes one of the gaps 16 formed by the tubing couplings 14. As the upper edge or apex of the'upstanding lip 31 first reaches the gap 16, fluid will be bypassed around the swab assembly since the-base portion 28 of the rubber cup is undersized and the lip is balanced by equal fluid pressure on both the inner and outer sides thereof. However, when the apex of the upstanding lip 30 reaches the lower end of the next adjacent tubing section 12, a pressure differential is created between the inside and outside surfaces of the lip so that the lip flares outwardly. After establishing sealing contact with the internal walls of the tubing, the lip is expanded into the gap 16 in the manner shown in FIGURE 1. The portion of the lip 31 bridging the gap 16 is under an extreme load which acts from the inside of the lip and bellows the lip into the gap. This condition of bulging at the coupling gaps 16 causes rapid wear and deterioration in sealing efliciency and often complete destruction of the cup occurs. This is particularly true where the reinforcing wires 34 have become worn to a thin diameter by their sliding contact with the internal walls of the tubing string. Since it is necessary to avoid the shearing off of the reinforcing wires 34 and loss of the same into the tubing string, it is usually necessary to replace the swab assembly after some two or three trips even though the swab is still sealing against the tubing Walls, in order to avoid the loss of the Wire elements into the string.

In FIGURE 2 of the drawings, a dilferent type of well swab assembly which has previously been used is illustrated. The left hand side of the view illustrated in FIGURE 2 shows the status of the swab assembly as it is being lowered into the tubing string. On the right hand side of the drawing, the status of the assembly is shown as it is pulled upwardly in the tubing string. As in the case of the swab assembly illustrated in FIGURE 1, the type of assembly illustrated in FIGURE 2 also includes the cylindrical mandrel 18 having a flange or retaining shoe 20 at the lower end thereof and a metallic cylindrical sleeve 24 slidingly positioned around the mandrel. A sleeve 40 of resilient material is bonded to the external periphery of the metallic sleeve 24 and carries a plurality of sealing lips 42 which are formed integrally therewith and extend outwardly toward the internal walls of the tubing string. In some types of swab assemblies, the sealing lips 42 extend, in their normal or unstressed state, in a radial or perpendicular direction with respect to the axis of the tubing string, while in other types such as that shown in FIGURE 2, the sealing lips extend upwardly at an angle with respect to the axis of the mandrel 18.

As the well swab assembly is lowered into the tubing string 10, the flexible sealing lips 42 offer very little resistance to the gravitation of the swab assembly down the string. All of the lips are in the upwardly extending position illustrated on the left side of FIGURE 2. As the swab assembly is pulled upwardly in the tubing string, however, each lip flips over or inverts under the impress of the fluid load and assumes the position shown by the upper and lower lips 42 on the right hand side of the FIGURE 2. As might be expected, the type of well swab assembly illustrated in FIGURE 2 is relatively inefiicient when carrying heavy fluid loads due to the limited loadcarrying capacity of the flexible lips 42, and actually the swab assembly will load to only about one third the capacity of the wire-reinforced type shown in FIGURE 1. The assembly of FIGURE 2, however, does have the important advantage of eliminating 'the reinforcing wires which, as previously explained, constitute a source of trouble in the later service life of the swab assemblies. It also is subjected to less stress and wear as it passes the gaps 16 at the tubing couplings 14.

The greatest disadvantage of the swab assembly type illustrated in FIGURE 2 is the tendency of the thin resilient sealing lips 42 to rupture at their hinge points, that is, at their intersection or point of joinder with the resilient sleeve 40, after a relatively short period of use. This is due to the great number of times the lips 42 are flipped over or reversed in passing up and down the tubing string and across the gaps 16 at the couplings 14.

In FIGURE 3 of the accompanying drawings, a basic embodiment of the present invention is illustrated. The conventional cylindrical mandrel constitutes no part of the present invention except insofar as the same functions in combination with the structures illustrated in FIGURES 3 through 8, and therefore the mandrel is not shown in any of these figures. In the preferred embodiment illustrated in FIGURE 3, a metallic cylindrical sleeve 50 dimensioned to fit slidingly around the mandrel is bonded to an annular sleeve of resilient material designated generally by reference character 52. The resilient sleeve 52 includes a load-carrying portion 54 which has a tapered lower face 56 to facilitate lowering of the swab assembly into the tubing string, and the resilient sleeve further includes a lip-supporting portion 58 which is of lesser radial thickness than the load-carrying portion 54. The radial thickness of the load-carrying portion 54 is selected to permit a clearance to exist between the load-carrying portion and the internal walls of the tubing string 10 and the outer surface of the load-carrying portion is substantially parallel with the inner periphery of the tubing string. A flexible sealing lip 66 is formed integrally with the lipsupporting portion 58 of the resilient sleeve 52 and extends radially outward therefrom toward the walls of the tubing. The flexible sealing lip 60 is relatively thin and is dimensioned to sealingly engage the internal walls of the tubing sections 12 when positioned in a plane extending normal to the axis of the tubing. In the case of the basic embodiment of the invention, this position is assumed by the lip when it is in its relaxed, unstressed status.

The operation of the basic embodiment illustrated in FIGURE 3 may best be explained by referring to FIG URES 9 through 13 of the drawings. In FIGURE 9, the swab cup assembly is being lowered into the tubing string 10 by a conventional wire line (not seen). At such time, the impress of the fluid below the swab assembly forces the metallic cylindrical sleeve 50 and its associated resilient sleeve 52 upwardly on the mandrel 18 so that a fluid passageway 64 through the mandrel is opened to permit the fluid in the tubing string 10 to bypass the well swab assembly. It will be noted that as the swab assembly descends into the tubing string 10, the flexible sealing lip 60 is flexed upwardly slightly by frictional contact with the tubing walls. However, the flexibility of the sealing lip 60 is sufliciently great that the frictional resistance of the lip in its contact with the tubing walls does not hinder the gravitation of the swab assembly to the bottom of the tubing string 10.

After the swab assembly has reached the bottom of the tubing string 10, its direction of travel is reversed and withdrawal from the string is commenced. At the instant of reversal and commencement of upward travel, the flexible sealing lip 60 is flexed downwardly into the sealing position illustrated in FIGURE 10. At the same time, the weight of the fluid column above the well swab assembly forces the metallic cylindrical sleeve 50 and its associated resilient sleeve 52 downwardly upon the mandrel 18 so that the fluid passageway 64 through the mandrel is closed. The flexibility of the resilient sealing lip 60 is such that it is sensitive to the lightest fluid loading, and it will almost instantaneously seal against the internal walls of the tubing at the instant that downward movement of the well swab assembly is terminated. A positive seal is established between the lip 60 and the walls of the tubing even despite existing irregularities in the wall. The flexibility of the sealing lip 6G is assured by the provision of the narrow groove or relief 62 between the lip 60 and the load-carrying portion 54 of the resilient sleeve 52.

Although the thinness and flexibility of the sealing lip 60 assure its capability of forming a fluid-tight seal with the walls of the tubing, these very characteristics, that is, flexibility and thinness, reduce its load-carrying capacity. I therefore provide a support for flexible lip 60 when the latter is under heavy hydrostatic loads. It is to this end that the long, thick, load-carrying portion 54 of the resilient sleeve 52 is provided.

The cooperation between the flexible sealing lip 60 and the load-carrying portion 54 of the resilient sleeve 52 as the sealing lip is subjected to heavy or extreme conditions of hydraulic loading is illustrated in FIGURE 11. The thin flexible sealing lip 60 has sufficient pliability to drop downwardly to the extent necessary and yet maintain its sealing engagement with the tubing wall. As the sealing lip 60 is forced downwardly, the load-carrying portion 54 of the resilient sleeve 52 is placed under compression and is distorted or expanded outwardly (in What is known as a barreling action) into engagement with the tubing wall.

It is important to note that the outward expansion of the load-carrying portion 54 of the resilient sleeve 52 is not the direct result of fluid pressure acting above it or at the inner side of the sealing lip 60 as is the case with the conventional upstanding lip-type Well swab assemblies heretofore utilized. Rather, the distortion or expansion of the load-carrying portion 54 results from the compressive action of the resilient sealing lip 60 as it is displaced downwardly by the hydrostatic forces of the fluid.

It is also important to understand that the dimensions of the load-carrying portion 54 are such that the frictional engagement between the load-carrying portion and the tubing walls is normally not great and appears to be less than normally occurs in the prior types of pressureactuated cup versions. In other words, the total extent of the expansion of the load-carrying portion 54 in a radial direction is not sufficiently great to result in any excessive frictional drag existing between the load-carrying portion and the tubing walls as the well swab assembly is pulled upwardly in the tubing string. The relatively slight expansion of the load-carrying portion 54 is also of advantage in that this portion of the swab assembly undergoes a remarkably low rate of wear and is less apt to be damaged as the swab assembly is pulled past certain distortions from concentricity of the tubing string and also past scale and paraffin deposits. The slight frictional contact of the load-carrying portion 54 with the internal walls of the tubing thus accounts in large measure for the relatively long service life of the well swab assemblies constructed in accordance with the present invention.

FIGURE 12 of the drawings illustrates the manner in which the well swab assembly of the invention is pulled past a coupling in the tubing string without being subjected to destructive wear or unbalanced stresses. The sealing lip 60 of the assembly, though of larger diameter than the internal diameter of the tubing sections 12, is of lesser diameter than the couplings 14 utilized to interconnect adjacent tubing sections. Consequently, as the lip 60 moves upwardly past the upper end of the lower tubing section 12, it snaps upwardly into its normal, unstressed position. The hydrostatic forces acting upon the upper and lower surface of the lip are equalized so that there is no loading on the lip as it enters the coupling gap 16. Since, as previously pointed out, the load-carrying portion 52 is of lesser diameter than the internal diameter of the sections 12 of tubing, a passageway for the fluid above the swab assembly is formed between the loadcarrying portion 54 and the walls of the tubing when the load-carrying portion is relieved from compression by the return of the sealing lip 60 to its normal, unflexed position.

It is thus apparent that some of the fluid carried above the well swab assembly will be bypassed around the sealing lip 60 and load-carrying portion 54 of the assembly during the time that these elements are moving across the gap 16 existing at the tubing coupling. However, the loss of fluid at this time is relatively small since the swab is being pulled upwardly in the tubing string 10 at a relatively great rate of speed as compared to the small dimension of the coupling gap 16. The fluid which is lost in this manner is more than compensated by the considerable improvement in load-carrying capacity which is realized when the well swab assembly of the present. invention is employed. Moreover, as will hereinafter ap pear, the basic embodiment of FIGURE 3 may be easily modified to provide a duplication of the structure there shown such that the swab assembly may completely bridge the gap 16 formed at the tubing couplings 14 and thereby continuously retain an effective seal with the tubing walls.

It will be readily apparent from the above discussion that the well swab assembly of the present invention is subjected to a minimum wear and distortion as it passes across the coupling gaps 16 during its ascent in the tubing string. This performance constitutes a major improvement over the upstanding lip type of swab cups previously I l utilized and illustrated in FIGURE 1 of the drawings.

In FIGURE 13, the well swab assembly is illustrated as it appears immediately after the flexible sealing lip 60 has traversed the coupling gap 16 and has again sealingly engaged the internal walls of the tubing section 12. Again the sealing lip 60 has been displaced downwardly into abutting contact with the load carrying portion 54 of the resilient sleeve 52. It is at this point that a major difference between the operation of the swab assembly of the present invention and the upstanding lip type of swab assembly of the prior art may be discerned. The only force tending to bellow or barrel outwardly the load-carrying portion 54 of the resilient sleeve 52 into the coupling gap 16 is that which is applied thereto by the downward movement of the flexible sealing lips 66. There is no internal fluid force acting radially outward upon the load-carrying portion 54 such as occurs in the case of the upstanding lip types of Well swab assemblies.

A modified embodiment of the present invention which is designed to improve the load-carrying capacity of the well swab assembly is illustrated in FIGURE 4. In the modified embodiment of FIGURE 4, a radially extending retaining flange 66 is provided at the base of the metallic cylindrical sleeve 50. The retaining flange 66 functions to permit the assembly to support a substantially increased fluid load, and also to confine or retain the load-carrying portion 54 of the resilient sleeve 52 against axial distortion. As a result of this confining function of the retaining flange 66, the radial expansion of the load-carrying portion 54 is greater than occurs in the preferred embodiment illustrated in FIGURE 3. Therefore, the increased loadcarrying capacity of the modified embodiment of the FIG- URE 4 is obtained at some slight sacrifice of low frictional resistance to the upward movement of the well swab asembly as a result of the contact between the loadcarrying portion 54 and the' tubing walls.

FIGURE 4a illustrates a slight modification which may be made in the embodiment of FIGURE 4 in order to minimize the pitching off or extrusion of the rubber or material of construction of the load-carrying portion 54 when a retaining flange 66 is employed. The modification comprises the provision of a relief or groove 68 which is positioned in the load-carrying portion 54 just above the retaining flange 66. The groove 68 will accommodate the axially displaced mass of the load-carrying portion 54 and will reduce the magnitude of the radial expansion which the load-carrying portion 54 undergoes when the well swab assembly is subjected to heavy fluid loading.

It is again importatnt to note that while it is proposed to trap and compress the flexible sealing lip 60 into tight sealing engagement with the tubing walls by utilizing the hydrostatic head of fluid over the well swab assembly, it is desirable to avoid trapping the load-carrying portion 54 between the metal cylindrical sleeve 24 and the tubing walls any more than is necessary. The primary object of the load-carrying portion 54 is to resiliently support the flexible sealing lip 60. In other words, the load-carrying portion 54 acts similar to a spring in compression to impart a yielding opposing force to the downward displacement of the flexible sealing lip 64).

As has been pointed out above, the use of a single sealing lip 60 and a single load-carrying portion 54 results in the disadvantage that the well swab assembly permits a small portion of the fluid to bypass the assembly as it traverses the coupling gaps 16. In general applications where average fluid loads are concerned, this is not es pecially of consequence, as it is the usual practice to install at least two units of the type illustrated in FIGURE 3 upon the mandrel 18. Some types of mandrels space the units, while others provide for stacking the units in abutting relation. On the other hand, the well swab assembly may be constructed, as shown in FIGURE 5, with a single, elongated, cylindrical metallic sleeve 70 12 having a surrounding resilient sleeve 72 bonded thereto. The resilient sleeve 72 comprises a plurality of load-carrying portions 74 and lip-supporting portions '76 placed in alternate or consecutive positions along the length of the metallic cylindrical sleeve 7%. Each of the lip-supporting portions 72 is formed integrally with a flexible sealing lip 78 which extends radially outward therefrom in the manner described above. The relative dimensions of the load-carrying portion 74, lip-supporting portion '76 and flexible lip 78 are identical to those hereinbefore specified.

The sealing and load-carrying action of the embodiment illusrtated in FIGURE 5 may best be understood by reference to FIGURES 14 and 15. From a perusal of these figures, it will be perceived that at least one of the flexible sealing lips 78 and its corresponding load-supporting portion 74 is functioning to establish a seal between the internal walls of the tubing and to support the fluid load, respectively, at all times during the passage of the swab assembly by a coupling gap 16. In FIGURE 14, the uppermost resilient sealing lip 78 has entered the gap 16 and has thus resumed its normal, relaxed position. The load-carrying portion 74 immediately below the flexible sealing lip 78 is therefore not compressed so as to undergo radial expansion. The lowermost flexible sealing lip 78 is, however, subjected to the impress of the fluid thereabove and is flexed downwardly into sealing contact with the walls of the tubing. The underlying fluid-carrying portion 74 of the resilient sleeve 72 is therefore placed in compression and expands radially outward into light frictional contact with the tubing walls.

In FIGURE 15, the uppermost flexible sealing lip 78 has traversed the coupling gap 16 and has reestablished sealing contact with tubing walls. It should also be apparent that the load-carrying portion 74 beneath the uppermost sealing lip 78 is compressed and is slightly expanded in a radial direction so that it extends slightly into the coupling gap 16. The lowermost sealing lip 78, on the other hand, is in its relaxed position, and the loadcarrying portion 74 thereunder has retracted to its normal, unstressed position.

As a further modification of the invention, as many as four of the sealing lips and load-carrying portions may be provided on the resilient sleeve of the well swab assembly to assure longer service life and greater insurance against the bypass. of fluid around the assembly as the assembly traverses the coupling gap. Also, as depicted in FIGURE 6, the flexible sea-ling lips, designated by reference character 80, may be tapered upwardly at a slight with respect to the axis of the metallic cylindrical sleeve 70, if desired. This construction has the advantage of presenting less frictional resistance to the downward gravitation of the well swab assembly in the tubing string 16. In other words, by virtue of the upward flare of the sealing lips .80, the lips do not contact with the tubing wall during the descent of the well swab assembly into the tubing string Ill, and a substantial amount of the wear ordinarily encountered in the downward trip is thereby avoided. The load-carrying portions 82 are, as in the preferred embodiment, of lesser diameter than the sealing lips and thus may pass irregularities and restrictions in the tubing string without becoming fouled or subjected to excessive abrasion.

It will be noted that in the modified emlb'odiment illustrated in FIGURE 6, the load-carrying portions 82 of the assembly terminate in a sernilip configuration at their upper ends 84. However, this configuration is primarily [for the purpose of reducing the void or relief 86 which exists between the load-carrying portions 82. and the flexible sealing lips -80. As previously pointed out, the purpose of the groove or relief 86 is to provide the utmost flexibility in the flexible sealing lip 80, and this groove is made as narrow as practicable in order to avoid overextending the flexible lip '80 as it is forced onto the loadcarrying portion 82. Except for the difference in the ac- 13 tion of the flexible sealing lips 80 during the downward travel of the well swab assembly, the modified embodiment of the invention depicted in FIGURE 6 involves similar operating characteristics to those which have been described in referring to the embodiment illustrated in FIGURE 5.

In FIGURE 7 of the drawings, yet another modified embodiment of the invention has been illustrated. Although the principles of operation are substantially similar to those which obtain in the case of the FIGURE embodiment, some improvement in overall operating efficiency and length of service life is realized as a result of the replacement of the metallic cylindrical sleeve with a helical wire spring 90. The sleeve 92 of resilient material is bonded to the periphery of the spring 90 and between the convolutions thereof. if desired, the spring 90 may be positioned more centrally in the mass of resilient material instead of at the inner periphery thereof as shown in the drawing. Also, as a further slight innovation of the helical spring-type swab assembly illustrated in FIGURE 7, a nonextrusion, back-up washer such as that designated by reference character 96 in FIGURE 8 may be utilized if desired.

The operation of the helical spring-type swab assembly is illustrated in FIGURES 16 and 17. In FIGURE 16, the swab assembly is shown as it is lowered in the tubing string. The sensitive sealing lips 98 are easily defiected upwardly to permit the assembly to fall freely. The load-carrying portions 94 of the resilient sleeve 92 afford ample clearance of the tubing walls, since during the downward trip the spring is in its relaxed or extended form so that the load-carrying portion-indeed, the entire resilient sleeve-4s in its molded or unstressed con figuration.

The position assumed by the helical spring-type well swab assembly as the flu-id load is lifted from the tubing string is illustrated in FIGURE 17. The flexible sealing lips 98 not passing across the coupling :gaps 16 are forced by hydrostatic pressure into sealing engagement with the internal walls of the tubing section and come to rest upon their respective load-carrying portions 94. As fluid loading increases, the spring 90 is compressed and its convolutions are moved closer together. in turn causes the resilient material between the convolutions to be expanded outwardly in a radial direction. The abutting contact of the load-carrying portion 94 with the walls of the tubing closes the clearance through which the sensitive lip member could be extruded under extreme conditions of wear and pressure.

, -It will be noted that the spacing of the convolutions of the helical spring 90 is purposely relatively short so as to minimize the expansion of the loadcarrying portions 94 in a radial direction. As previously pointed out, it is desirable that extreme loading and compression of the loadcarrying portions be avoided since this will result in excessive frictional contact with the walls of the tubing. As the coils of the helical spring 90 are compressed, the resilient material trapped between the coils prevents the coils from fully closing or coming in cont-act with each other. However, the trapped resilient material is highly compressed between the coils and becomes, in effect, a series of thin gaskets which effectively seal against the spring convolutions and the mandrel so as to prevent fluid from infiltrating between the mandrel and the spring as well as providing increased resistance to any fluid forces acting from within the spring. Thus, the tendency of such forces to distort the mass of resilient material into recesses in the tubing walls is reduced.

The use of the helical wire spring 90 in the present invention presents an operating principle which is directly opposed to the operating principle underlying the use of wire members in previously used well swab assemblies, In such previous well swab assemblies, the wire members are included in the sealing structure to reinforce the sealing lips' and to provide a controlled resistance to the impress of hydrostatic forces, and yet they must have sufficient flexibility to follow the seal structure in its movement to and from sealing engagement with the tubing wall. The wire structures of the prior art contemplate the vertical positioning of such wires in the sealing structure usually in basket form, and such wires are intended to form a supporting bridge for the seal structure to resist undue outward displacement of such structure, as at the time of passing coupling gaps. With this arrangement, the outward flexure of the wirereinforcing members toward the tubing walls results in the opening or increasing of the circumferential spacing between such wires. Such increase of spacing between the vertical wires in turn permits the hydrostatic forces acting from the inside of the upstanding lips an enhanced opportunity to force the lips into the coupling gaps where they soon become severely worn or damaged. In other words, in this previous type of Well swab assembly, the wire-reinforcement members were placed at the outside of the upstanding sealing lips and were intended to provide a direct means for resisting the displacement and deformation of the lip, rather than for the purpose of improving the control which was maintained over the degree of displacement and deformation of the lip as it was passed into contact with the tubing wall.

In the present invention, the coil spring which is provided at the inner periphery of the resilient sleeve or in the center of the body thereof, affords an entirely different functional characteristic than the function of the wire members in the previously devised swab assemblies. In the present invention, as the fluid load increases, the spacing between the convolutions of the helical spring, which may be said to correspond to the spacing between the wire-reinforcing members of the prior art swab assemblies, is decreased as opposed to the increased spacing occurring in the previous swab assemblies and described above. When the fluid forces acting downwardly on the swab assembly of the helical spring embodiment of the present invention are slight, the spring is compressed only slightly. Under this condition, although the fluid forces do have some effect in displacing the resilient load-carrying portion outwardly, this effect is minor since the resilient material is exposed to compression only between the open coils of the spring structure, and hence very little radial displacement occurs.

As the magnitude of the fluid load increases and the need for a more substantial supporting structure for the sealing lip is realized, the fluid forces act to compress the spring to a considerably greater degree. This narrows the convolution spacing and increases the compression of the portions of the resilient material between the convolutions. The load-carrying portion is radially expanded by the shortening of the spring to provide increased support for the heavier fluid load. Although the hydrostatic forces exerted by the fluid .are effective, therefore, in shortening the spring, the reaction of the load-carrying portion of the swab assembly is actually a mechanical result of the alternation of the status in the spring. This is directly opposed to the manner of functioning of the previously used, upstanding lip, wire-reinforced type of swab assemblies.

From the foregoing description, it will be apparent that the well swab assembly of the present invention presents a highly novel device for swabbing well tubing more efficiently and over longer operating periods than any previously devised type of swab assembly. The principles of operation obtaining in the swab assembly of the invention are quite different from any which have previously been relied upon. In all of the embodiments hereinbefore discussed, :a sensitive, flexible sealing lip is immediately responsive to even very slight fluid pressures to establish a tight seal with the internal walls of the well tubing. The flexibility of the lip is such that the seal is maintained even in instances of restrictions, or

, distortions of concentricity, in the tubing string. HOW? ever, the sealing lip is not relied upon to carry the fluid load. For this purpose, a thick, elongated, resilient loadcarrying element is provided and is positioned with respect to the sealing lip so that immediately after the lip is biased into sealing engagement, the ever-increasing load is borne by the load-carrying portion.

Another important aspect of the invention is the arrangement of the various elements of the swab assembly in such a way that the exposed resilient material of the assembly does not undergo any substantial wear as the assembly moves past couplings in the tubing string. Also, little or no resistance is offered to the downward movement of the assembly into the tubing string, and wear of the resilient-sealing and load-carrying elements is minimized during such descent.

Although a number of minor modifications and variations in the basic structure herein described Will occur to those skilled in the art, these modifications and variations may, in most instances, be made without departure from the basic inventive concepts and principles herein disclosed for the first time. Therefore, insofar as the novel operating principles of my device may be employed in subsequent modified forms and variations of well swab assemblies, such assemblies are deemed to be encompassed by the spirit and scope of this invention, except as the same may be necessarily limited by the appended claims.

I claim:

1. A well swab for swabbing the internal walls of, and lifting fluid from, oil well tubing or the like comprising, in combination with said tubing:

a metallic, generally cylindrical member;

an annular sleeve of resilient material around said metallic, generally cylindrical member and bonded thereto, said sleeve having a load-carrying portion of lesser outside diameter than the internal diameter of said tubing and extending from one end of said cylindrical member over a major portion of the length thereof and terminating in an abrupt, annular shoulder, the length of said load-carrying portion being greater than the radial thickness thereof, and said sleeve further having a lip-supporting portion of smaller radial thickness than said load-carrying portion and extending axially along said cylindrical member from said load-carrying portion toward the other end of said cylindrical member;

and an annular, flexible lip of resilient material formed integrally with said lip-supporting portion and extending outwardly therefrom toward the internal Walls of said tubing, said flexible lip being dimensioned to sealingly engage the internal walls of said tubing when said-lip occupies a plane extending normal to the axis of said tubing and being spaced from the annular shoulder of said load-carrying portion by a distance sufiiciently small to permit said lip to sealingly engage the internal walls of said tubing when said flexible lip is flexed by a hydrostatic pressure into abutting contact with said shoulder.

2. A well swab as claimed in claim 1 wherein said flexible lip extends normal to the axis of said metallic, generally cylindrical member in its relaxed, unstressed state.

3. A well swab as claimed in claim 1 wherein said flexible lip extends at an angle of between 45 and 90 degrees with respect to the axis of said cylindrical member when said lip is in its relaxed, unstressed state.

4. A well swab as claimed in claim 1 wherein said metallic, generally cylindrical member is a metallic sleeve bonded to the inner peripheral wall of said sleeve of resilient material.

5. A well swab as claimed in claim 1 wherein said metallic, generally cylindrical member is a wire helical compression spring bonded to said sleeve of resilient material adjacent the inner periphery thereof, and sandtwiching said resilient material between the convolutions of said spring whereby the compression of said spring compresses the resilient material between said convolutions.

6. A well swab as claimed in claim 1 and further characterized to include at least one additional sleeve of resilient material around said metal, generally cylindrical member, and having its l0ad-carrying portion positioned in abutting relation to the lip-supporting portion of said first-mentioned sleeve of resilient material, the length of the load-carrying portion of each of said additional sleeves of resilient material being greater than the radial thickness thereof;

and an annular, flexible lip of resilient material formed integrally with the lip-supporting portion of each of said additional sleeves of resilient material and extending outwardly therefrom toward the internal walls of said tubing, said flexible lips each being dimensioned to sealingly engage the internal walls of said tubing when said lip occupies a plane extending normal to the axis of said tubing and being spaced from their respective associated load-carrying portions by a distance sufliciently small to permit said lip to sealingly engage the internal walls of said tubing when said flexible lip is flexed by hydraulic pressure into abutting contact with said load-carrying portion.

7. A well swab as claimed in claim 4 and further characterized to include an annular, radially extending flange secured concentrically to said metallic sleeve adjacent said one end thereof, said flange extending into the load-carrying portion of said sleeve of resilient material for limiting axial movement of said load-carrying portion toward said one end of said metallic sleeve when said supporting portion is subjected to a compressive force acting through said flexible lip in a direction normal to said flange.

8. A well swab as claimed in claim 5 and further, characterized to include an annular retainer ring embedded in said load-carrying portion adjacent said one end of said helical compression spring and extending radially through a major portion of said load-carrying portion from the inner peripheral wall thereof for limiting axial movement of said load-carrying portion toward said one end of said metallic member when said load-carrying portion is subjected to a compressive force acting through said flexible lip in a direction normal to said ring.

9. In a well swab for swabbing the inner periphery of, and lifting fluid from, oil well tubing and the like, comprising: v

a reinforcing sleeve of a size to be inserted inthe tubing;

an annular, resilient lip bonded around the sleeve and being responsive to fluid loading created by raising the swab in a tubing containing fluid for flexure into sealing engagement with the inner periphery of the tubing; and

an annular body of resilient material secured around the sleeve in a position to support and be distorted by said lip when said lip is flexed in response tofluid loading, said body having an outer surface parallel with the inner periphery of the tubing, and the length of said body being of a size to provide a barreling effect when said body is loaded by said lip. to provide engagement of said outer surface with the inner pe; riphery of the tubing.

10. In a Well swab for swabbing the inner periphery of, and lifting fluid from, oil well tubing and the like, comprising:

a reinforcing sleeve of a size to be inserted in the tubing;

an annular, resilient lip bonded around the sleeve and being responsive to fluid loading created by raising the swab in a tubing containing fluid for flexure int-o sealing engagement with the inner periphery of the tubing; and

11. In a well swab for swabbing the inner periphery of, and lifting fluid (from, oil well tubing and the like, comprising:

a reinforcing sleeve of a size to be inserted in the tubing;

a plurality of annular, resilient lips bonded around the sleeve in spaced relation along the length of the sleeve, each of said lips being responsive to fluid loading for flexure into sealing engagement with the inner periphery of the tubing; and

a plurality of annular bodies of resilient material bonded around the sleeve, each body being positioned to support and be distorted by one of said lips when the respective lip is flexed in response to fluid loading, each of said bodies having an outer surface parallel with the inner periphery of the tubing, and the length of each of said bodies, along said outer surface thereof, being greater than the radial thickness of the respective body measured from said outer surface thereof to the outer periphery of said sleeve.

12. In a well swab for swabbing the inner periphery of, and lifting fluid from, oil well tubing and the like, comprising:

a reinforcing sleeve having an outer diameter less than the inner diameter of the tubing in which the swab is to be used;

i an annular body of resilient material bonded around the sleeve in a position to support and be distorted by said lip when said lip is flexed in response to fluid loading, said body having an outer surface substantially parallel with the inner periphery of the tubing, the length of said body, along said outer surface, being at least twice as great as the radial thickness of said body measured from said outer surface to the outer periphery of said sleeve.

13. In combination with a string of tubing, a swab for lifting fluid from the tubing, comprising:

a reinforcing sleeve having an outer diameter less than the inner diameter of the tubing;

an annular, resilient lip bonded around the sleeve and being responsive to fluid loading created by raising the swab in the tubing for flexure into sealing engagement with the inner periphery of the tubing; and

an annular body of resilient material bonded around the sleeve in a position to support and be distorted by said lip when said lip is flexed in response to fluid loading, said body having an outer surface substantially parallel with the inner periphery of the tubing and, in the relaxed condition of said body, said outer surface being spaced from the inner peripery of the tubing a distance less than the radial thickness of said body, the length and radial thickness of said body being sufficient to provide a barreling effect and engagement of said outer surface with the inner periphery of the tubing when the swab is lifting fluid from the tubing.

14. In combination with a string of tubing, a swab for lifting fluid from the tubing, comprising:

18 lip of resilient material bonded around the sleeve and being responsive to fluid loading for flexure into sealing engagement with the inner periphery of i the tubing; and an annular body of resilient material seoured around the sleeve in a position to support and be distorted by said lip when said lip is flexed in response to fluid loading, said body having an outer surface parallel with the inner periphery of the tubing and, in the relaxed condition of said body, said outer surface being spaced from the inner periphery of the tubing a distance less than the radial thickness of said body, and the length of said body, along said 7 outer surface, being greater than the radial distance between the sleeve and the inner periphery of the tubing. 1

reinforcing sleeve having an outer diameter less than the inner diameter of the tubing;

an annular, resilient lip bonded around the sleeve and being responsive to fluid loading for flexure into sealing engagement with the inner periphery of the tubing; and

an annular body of resilient material secured around the sleeve in a position to support and be distorted by said lip when said lip is flexed in response to fluid loading, said body having an outer surface parallel with the inner periphery of the tubing and, in the relaxed condition of said body, said outer surface being spaced from the inner periphery of the tubing a distance less than the radial thickness of said body, and the length of said body, along said outer surface, being at (least twice as great as the radial thickness of said body measured [from said outer surface to the outer periphery of said sleeve.

16. In combination with a string. of tubing having coupling recesses therein, a swab for lifting fluid from the tubing, comprising:

an annular body of resilient material bonded around 17. In a well swab for swabbing the inner periphery of,

and

lifting fluid from, oil well tubing and the like, comprising reinforcing sleeve of a size to be inserted in the tubing; and

generally cylindrical mass of un-reinforced resilient material bonded around the sleeve having its upper and lower ends coterminous with the upper and lower ends of the sleeve; said mass of resilient material being shaped to provide a plurality of vertically spaced lip portions responsive to fluid loading as the swab is raised in the tubing for flexure into sealing engagement with the inner periphery of the tubing, and shaped to provide a support portion under each lip portion responsive to fluid loading of the respective lip portion for distortion radially outward into engagement with the inner periphery of the tubing, each of said support portions having an outer diameter less than the inner diameter of the tubing in the relaxed condition of the support portion and an outer surface parallel with the inner periphery of the tubing, and said outer surface having a length greater than the radial thickness of the respective support portion measured between said outer surface and said sleeve.

18. In a well swab for swabbing the inner periphery of, and lifting fluid from, oil well tubing and the like, comprising:

a reinforcing sleeve of a size to be inserted in the tubing; and

a generally cylindrical mass of un-reinforced resilient material bonded around the sleeve having its upper and lower ends coterminous with the upper and lower ends of the sleeve; said mass of resilient material being shaped to provide a plurality of vertically spaced lip portions responsive to fluid loading as the swab is raised in the tubing for flexure into sealing engagement with the inner periphery of the tubing, and shaped to provide a support portion under each lip portion responsive to fluid loading of the respective lip portion for distortion radially outward into engagement with the inner periphery of the tubing, each of said support portions having an outer diameter less than the inner diameter of the tubing in the relaxed condition of the support portion and an outer surface substantially parallel with the inner periphery of the tubing, and said outer surface having a length at least twice the radial thickness of the respective support portion measured between said outer surface and said sleeve.

19. In combination with a string of tubing having coupling recesses therein, a swab for lifting fluid from the tubing, comprising:

a reinforcing sleeve of a size to be inserted in the tubing; and

a generally cylindrical mass of un-reinforced resilient material bonded around the sleeve having its upper and lower ends coterminous with the upper and lower ends of the sleeve; said mass of resilient material being shaped to provide a plurality of vertically spaced lip portions responsive to fluid loading as the swab is raised in the tubing for fiexure into sealing engagementwith the inner periphery of the tub ing, and shaped to provide a support portion under each lip portion responsive to fluid loading of the respective lip portion for distortion radially outward into engagement with the inner periphery of the tubing, each of said support portions having an outer diameter less than the inner diameter of the tubing in the relaxed condition of the support portion and an outer surface substantially parallel with the inner periphery of the tubing, and said outer surface having a length greater than the length of each coupling recess in the tubing string.

20. A swab as claimed in claim 11 wherein said annular bodies have a smaller diameter than the diameter of the well tubing and said lips have a larger diameter than said load-carrying portions.

21. In a well swab for swabbing the inner periphery of, and lifting fluid from, oil well tubing and the like, comprising:

a reinforcing sleeve of a size to be inserted in the tubing; anda generally cylindrical mass of un-reinforced resilient material bonded around the sleeve; said mass of resilient material being shaped to provide a lip portion responsive ot fluid loading as the swab is raised in the tubing for flexure into sealing engagement with the inner periphery of the tubing, and shaped to provide a support portion under the lip portion res-ponsive to the fluid loading of the lip portion for distortion radially outward into engagement with the inner periphery of the tubing, said support portion having an outer diameter appreciably less than the inner diameter of the tubing in the relaxed condition of the support portion so as not to sealingly engage the tubing and so provide a bypass of fluid around the swab when the swab is moving down the tubing, and said support portion having an outer surface substantially parallel with the inner periphery of the tubing, said support portion having a length at least twice the radial thickness thereof.

References Cited by the Examiner UNITED STATES PATENTS 1,981,262 11/1934 Burt 9278 2,109,913 3/1938 Thaheld 309-52 2,687,845 8/1954 Young et al 309-51 X 2,711,939 6/1955 Losey 30952 2,913,293 11/1959 Dibley et al 30951 3,023,062 2/1962 Waldrop 30952 EDGAR W. GEOGHEGAN, Primary Examiner.

KARL I. ALBRECHT, Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,266,384 August 16, 1966 Domer Scaramucci It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 5, line 1, for "cocncept" read concept line 42, for "uwardly" read upwardly column 7, line 47, for "exterted" read exerted column 11, line 33, strike out "the" second occurrence; column 12, line 50, for "with respect" read angle with respect column 20, line 19, for "0t" read to Signed and sealed this 1st day of August 1967.

(SEAL) Attest:

EDWARD J. BRENNER Commissioner of Patents Edward M. Fletcher, J r.

Attesting Officer

Claims

1. A WELL SWAB FOR SWABBING THE INTERNAL WALLS OF, AND LIFTING FLUID FROM, OIL WELL TUBING OR THE LIKE COMPRISING, IN COMBINATION WITH SAID TUBING: A METALLIC, GENERALLY CYLINDRICAL MEMBER; AN ANNULAR SLEEVE OF RESILIENT MATERIAL AROUND SAID METALLIC, GENERALLY CYLINDRICAL MEMBER AND BONDED THERETO, SAID SLEEVE HAVING A LOAD-CARRYING PORTION OF LESSER OUTSIDE DIAMETER THAN THE INTERNAL DIAMETER OF SAID TUBING AND EXTENDING FROM ONE END OF SAID CYLINDRICAL MEMBER OVER A MOJOR PORTION OF THE LENGTH THEREOF AND TERMINATING IN AN ABRUPT, ANNULAR SHOULDER, THE LENGTH OF SAID LOAD-CARRYING PORTION BEING GREATER THAN THE RADIAL THICKNESS THEREOF, AND SAID SLEEVE FURTHER HAVING A LIP-SUPPORTING PORTION OF SMALLER RADIAL THICKNESS THAN SAID LOAD-CARRYING PORTION AND EXTENDING AXIALLY ALONG SAID CYLINDRICAL MEMBER FROM SAID LOAD-CARRYING PORTION TOWARD THE OTHER END OF SAID CYLINDRICAL MEMBER; AND AN ANNULAR, FLEXIBLE LIP OF RESILIENT MATERIAL FORMED INTEGRALLY WITH SAID LIP-SUPPORTING PORTION AND EXTENDING OUTWARDLY THEREFROM TOWARD THE INTERNAL WALLS OF SAID TUBING, SAID FLEXIBLE LIP BEING DIMENSIONED TO SEALINGLY ENGAGE THE INTERNAL WALLS OF SAID TUBING WHEN SAID LIP OCCUPIES A PLANE EXTENDING NORMAL TO THE AXIS OF SAID TUBING AND BEING SPACED FROM THE ANNULAR SHOULDER OF SAID LOAD-CARRYING PORTION BY A DISTANCE SUFFICIENTLY SMALL TO PERMIT SAID LIP TO SEALINGLY ENGAGE THE INTERNAL WALLS OF SAID TUBING WHEN SAID FLEXIBLE LIP IS FLEXED BY A HYDROSATIC PRESSURE INTO ABUTTING CONTACT WITH SAID SHOULDER.