US3407711A - Swab assembly - Google Patents

Description

Oct. 29, 1968 J, c. WEBBER 3,407,711

swAB ASSEMBLY Filed April 25, 1966 /f//f /ff /7 /f/Z r 'Arr RvEY K United States Patent Olce 3,407,71 l Patented Oct. 29, 1968 SWAB ASSEMBLY Jack C. Webber, Corpus Christi, Tex., assgnor to Mission Manufacturing Company, Houston, Tex., a corporation of Delaware Filed Apr. 25, 1966, Ser. No. 544,902

` 8 Claims. ('Cl. 92-180) ABSTRACT or THE DISCLOSURE This patent shows a mandrel and swabs for swabbing a well in which alternate lands and grooves are provided on a fluted mandrel. The alternate lands and grooves permit the swab rubbers to misalign as the swab is run into the well and align the 4swabs as it is removed from the well.

This invention relates to swab assemblies Yfor swabbing wells.

It is frequently necessary to remove liquid standing in a petroleum well to start the well flowing. This is con ventionally done by a swab which is lowered into the well to a point under a desired amount of liquid. The swab is then raised to remove liquid from the well. In this manner the liquid is removed from the well until it begins to flow.

Well tubing is seldom straight and true. Frequent tig-ht spots and eccentric points are encountered. Where a plurality of swab rubbers are employed on a single mandrel, they sometimes bridge across eccentric areas r tight spots. When this occurs, diiculty is experienced in getting the swab to fall down the tubing.

Swabs of the type which employ a movable swab rubber on a mandrel which functions as a check valve sometimes become sanded up and resist movement on the mandrel due to the relatively close tolerance between the mandrel and the bore through the swab` It is an object of this invention to provide a swab assembly which will readily fall through crooked or misaligned sections of tubing without impairing the etliciency of the swab assembly.

Another object is to provide a mandrel and swab assembly in which swab rubbers may be misaligned individually with the mandrel while being run into the well, and which are returned to aligned condition during swabbing.

Another object is to provide a swab assembly which is less likely to sand up due to large clearances bet-Ween the mandrel and most of the area of the swab rubber.

-Other objects, features and advantages of the invention will be apparent from the drawings, the specication and the claims.

In the drawings, wherein an illustrative embodiment of this invention is shown, and wherein like numerals indicate like parts;

FIGURE 1 is a view partly in elevation and partly in section through a swab assembly constructed in accordance with this invention with the swab assembly shown moving downwardly through a well tubing;

FIGURE 2 is a fragmentary view similar to FIGURE 1 showing the swab assembly moving upwardly in the well and lifting a load of liquid; and

FIGURE 3 is a sectional view along the line 3-3 of FIGURE 1. f

In accordance with this invention, the mandrel and swab rubbers are arranged insuch manner that with the swab rubbers in their upper position they may tilt about the mandrel to a nonaligned position. This is accomplished by providing clearance between the extremities of the swab rubber and the mandrel whichwill permit relative misalignment. This concept is carried out with the mandrel is pulled upward, the swab rubbers move to their down position where they are held in aligned position with each other and with the mandrel by a pair of spaced lands on the mandrel. It might be noted that these lands occupy an intermediate position o f each swab rubber during running so that the swab rubbers may`mis align, as discussed above. l

Referring now to the drawings, a well tubing compris= ing tubing sections 10 and 1l are s'hown to be eccentrically connected. The' amount of eccentricity is exaggerated but illustrates the manner in which an eccentricity can occur. Many other tubing conditions also occur which make is difficult to pass t-wo or more swab rubbers which are held in aligned position.

Within the tubing there is shown a mandrel indicated generally at 12 which is suspended from a wireline 13. The mandrel 12 is shown to be misaligned relative to the tubing. Again, the degree of misalignment is exaggerated for purposes of illustration.

A plurality of swab rubbers indicated generally at 14 are carried on the mandrel. Two swab rubbers are shown in full line and a third swab ru-bber is shown in dotted line to illustrate that one or more swab rubbers may be carried on the mandrel, depending upon the amount of fluid to be lifted. While this invention has its greatest usefulness where two or more swab rubbers are present, it will be appreciated that the invention is also useful where only a single swab rubber is used, as the ability of even a single swab rubber to misalign relative to the mandrel permits greater freedom in running the swab assembly downwardly in the tubing. A full description of the type of swab -rubber illustrated is found in Webber Patent No. 2,633,808.

Referring to the mandrel in detail, it is seen t-o comprise an upper section indicated generally at 1S, an intermediate section indicated generally at 16, and a lower section indicated generally at 17. The several swab rubbers 14 are mounted on the intermediate section for loose engagement therewith and for movement axially of the mandrel.

The intermediate section of the mandrel 16 is provided with a plurality of lands 18, 19, 20 and 21. These lands alternate with grooves 22, 23, 24 and 25. The lands and grooves extend circumferentially about the intermediate section of the mandrel.

Provision is made for flow of fluid through the swab assembly. This may be carried out in any desired manner. In the illustrated embodiment of the invention a plurality of flutes 26 are provided. These liutes extend through the intermediate section of the mandrel and a portion of the top section of the mandrel 15.

The top section of the mandrel 15 is enlarged relative to the lands and provides a shoulder 27 which serves as a stop to limit relative movement of the swabs.

The lower section of the mandrel 17 is also enlarged relative to the lands and grooves and provides a stop 28 for limiting downward movement of the swab rubbers relative to the mandrel.

The several lands and grooves are :arranged so that they permit the several swab rubbers to misalign relative to the mandrel when in their upper position, and hold the swab rubbers in alignment when in their lower position. The distance from shoulder 27 to the center of land 18 is approximately half the distance from center to center of lands 18 and 19. The distance from center to center of lands 18 and 19 is the same as the distance from center to center of lands 19 and 20. The distance from center of land 20 to shoulder 28 is the same as the distance from center to center of lands 19 and 20. The land 21 is preferably spaced from shoulder 28 a shoft distance to reduce the possibilities of sanding up about this land.

With the relationship described above, each of the swab rubbers 14 will have its intermediate section overlying a land when the several swabs are in the up position as shown in FIGURE l. The extremities of the swab rubbers will overlie the grooves, and thus each swab rubber can rock about its associated land to misaligned position as illustrated in FIGURE l. In locating land 21, it is apparent that it could be positioned anywhere between the stop 28 and the lower end of the swab 14a shown in dashed outline, as such location will permit the lower lswab to misalign.

With the relationship of the several lands and grooves described above, it is apparent that when the swab rubbers, which are of equal length, move to their downward position as shown in FIGURE 2, each swab rubber overlies two lands to hold the swab rubbers in aligned position. It should be noted that the bore 14h through the swab rubbers is slightly larger in diameter than the diameter of a circle in which the several lands extend. This permits the swab rubbers to slide longitudinally over the mandrel. The clearance, however, is such that with the swab rubbers in down position and engaged with two spaced lands, the swab rubbers are held in substantially aligned position.

It will be noted that as the swab rubbers move to down position in aligned condition, they engage each other and the lowermost swab rubber seats on shoulder 28 and seals therewith. This prevents ow through the several liutes 26, and thus the swab rubbers function as check valves to control ow through the several flutes.

The operative position of the mandrel and swabs is shown in FIGURE l during running of the swab. The swab rubbers will drag against the wall of the tubing and will remain in their upper position during lowering of the mandrel. They thus will be able to misalign as shown in the drawings. As the swab falls through the liquid in the well, the liquid will pass up through flutes 26 and the swab may readily pass through such liquid. The swab rubbers may misalign relative to each other and to the mandrel so that they will readily pass through tight spots in the tubing.

After the swab is lowered to a desired level, it is raised and the several swab elements will move downwardly relative to the mandrel. The lowermost swab element will seat on shoulder 28 and the upper end of this swab ele- -ment will terminate at a position overlying the land 20. The next swab element will move down to position its lower extremity over the land 20 and abut against the lower swab element. This swabs upper extremity will overlie the land 19. In like manner, if a third swab rubber is present it will straddle the groove 23 and be aligned by lands 18 and 19. In this position, ow through the utes is stopped and the several swab rubbers are held in aligned position with the mandrel and are in position to raise uid in the well.

This invention is of particular value where swab elements of the type employing radial flanges are concerned, as these radial anges may be relatively flexible and relatively incapable of centering themselves on the swab mandrel. It will be appreciated that as the swab mandrel is moved upwardly and a load of liquid is imposed on the swabs, that a substantial downward force is exerted on the swab rubbers. If they are not aligned with the mandrel at .this time, they will probably be held in the position they assume at the time that a load is placed on the swab rubbers. If they were eccentric, excessive uneven wear would occur which would affect the life of the swab. It is, therefore, important that the swab rubbers be in aligned position so that they are automatically centered before a substantial load is imposed on the swab rubbers. Of course, there is no substantial problem in pulling the swab rubbers upwardly through eccentric or tight places as the swab rubbers may be readily pulled lthrough any space through which they can be dropped. The several anges may readily give to pass through bent, eccentric or tight places without affecting the operation of the swab.

It will be appreciated that by using the relatively small lands and the relatively long grooves, that substantial spaces are provided between the swab rubbers and the mandrel, and there is much less likelihood of sand lodging between the lands and the swab rubbers and preventing their proper operation.

In the explanation of the relative position of the lands and grooves, reference was made to the center of the lands. It will be appreciated that it is only necessary to have the several swabs engage lands, and adjacent extremities of the two swabs might engage any portion of a particular land and function properly, as the only purpose of the land is to align the swab rubbers.

While swab rubbers of the type having radial flanges 29 are illustrated, it will be apparent that swab rubbers of any desired type may be utilized.

The foregoing disclosure and description of the invention are illustrative and explanatory thereof and various changes in the size, shape and materials, as well as in the details of the illustrated construction, may be made within the scope of the appended claims without departing from the spirit of the invention.

What is claimed is: 1. A swab assembly comprising, a mandrel, at least one swab rubber on said mandrel movable between upper and lower positions on said mandrel,

cooperable means on said mandrel and each swab rubber permitting misalignment of said mandrel and each swab rubber when the swab rubbers are in their upper position and aligning each swab rubber on said mandrel when said swab rubbers are in their lower position.

2. The swab assembly of claim 1 wherein said mandrel is uted to allow fluid low therethrough when the swab rubbers are in their upper positions, and wherein the lower swab rubber sealingly engages a stop when the swab rubbers are in their lower position to prevent flow through said flutes.

3. The swab assembly of claim 1 wherein each swab rubber comprises a plurality of generally radially extending resilient exible flanges for engaging the wall of a tubing.

`4. A swab assembly comprising,

an elongate mandrel having a plurality of circumferentially extending alternate lands and grooves on its intermediate section,

enlarged upper and lower sections on said mandrel above and below said intermediate section,

at least one swab rubber on the intermediate section,

each swab rubber having a bore therethrough loosely and slidably receiving said lands,

said lower enlarged section providing a stop positioning each swab rubber in engagement with two spaced lands to center each swab rubber when in the down position,

said upper enlarged section providing a stop positioning each swab rubber with its intermediate section over a land and its extremities over grooves to permit misalignment of the mandrel and each swab rubber with each swab rubber in its up position.

5. The swab assembly of claim 4 wherein the intermediate section of the mandrel is fluted to provide for flow of uid with each swab rubber in its upper position and wherein the lower mandrel section and a swab rubber engage and close off the passageways provided by said flutes when each swab rubber is in its lower position.

6. The swab assembly of claim 5 wherein each swab rubber comprises a plurality of generally radially extending resilient flexible anges for engaging the wall of the tubing.

7. A swab mandrel comprising, an intermediate section and enlarged upper and lower sections above and below said intermediate section, said upper and lower sections providing stops to limit travel of swabs on the intermediate section, alternate lands and grooves on said intermediate section with the distance between the upper section and the center of the uppermost land being approximately one-half the distance between the center of the uppermost land and the center of the uppermost land and the center of the next uppermost land, the distance between the lower section and the center of the second lowermost land and the distance be- 6 tween any two intermediate lands being approximately equal. 8. The swab mandrel of claim 7 wherein the intermediate section is uted.

References Cited MARTIN P. SCHWADRON, Primary Examiner. G. N. BAUM, Assistant Examiner.

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