US3318607A

US3318607A - Well tools

Info

Publication number: US3318607A
Application number: US359181A
Authority: US
Inventors: James A Wilson
Original assignee: Individual
Current assignee: Individual
Priority date: 1964-04-13
Filing date: 1964-04-13
Publication date: 1967-05-09
Anticipated expiration: 1984-05-09

Description

J. A. WILSON May 9, 1967 WELL TOOLS Filed April 13, 1964 a. P w w w a a b a E c. d. 5 a. 7 6 5 2 6 MW w w "w W 2 5 5 5 W L L m 7 a \w u 5 3 If 1 I 9 lg r: V 6 l6 a 3 3 Km INVENTOR James A. Wilson United States Patent This invention relates to well tools and more particularly to well swabs.

An object of the invention is to provide a new and improved well swab which is movable in a well flow conductor for lifting fluids therein. A

Another object is to provide a well swab having a seal assembly including a tubular support on which is mounted a seal element for sealing between the tubular support and a flow conductor and means for moving the tubular support in the flow conductor and for closing the passage thereof when the tubular support is moved upwardly in a flow conductor and for opening the passage to permit flow of fluids therethrough when the tubular support is moved downwardly in the flow conductor, wherein the seal element is expanded into sealing engagement with the flow conductor by the fluid load supported thereby during upward movement of the well swab in the flow conductor.

Still another object is to provide a well swab'assembly wherein the seal element is of such structure that the force with which the seal element is held in sealing engagement with a well flow conductor varies in accordance with the fluid load being lifted whereby the force necessary to move the well swab under load is held to a minimum and the wear of the seal element during its upward movement in the flow conductor is also held to a minimum for any predetermined load condition.

A further object is to provide a well swab wherein the sealing element of the tubular support is of a resilient substance, is substantially tubular in form, and has longitudinally aligned outer annular portions individually expansible into sealing engagement with a wellflow con: ductor, each external annular portion being supported by lower outer portions whereby the area of the sealing element in sealing engagement with the well flow conductor increases with the load .as the individual sections are progressively expanded as the load increases.

A- still further object is to provide a well swab wherein the progressive and consecutive expansion of the longitudinally aligned outer annular portions of the seal element minimize the sealing and frictional engagement of the seal element with the well flow conductor since only such number of the outer portions are expanded into sealing engagement with the flow conductor as is necessitated by the fluid load being lifted by the swab.

A still further object is to provide a well swab of the type described wherein the resilient seal element has a plurality of longitudinally aligned annular portions formed by longitudinally spaced annular cuts or slits in the seal element, the adjacent surfaces of adjacent annular portions abutting one another whereby each annular portion is always supported by the annular portions therebelow and whereby each annular portion is expan'sible outwardly as it is compressed by the fluid load;

Another object is to provide a well swab wherein the annular portions formed by the slits inclined radially upwardly and outwardly relative to the longitudinal axis of the well swab whereby a longitudinal force acting on the seal element in one longitudinal direction tends to expand radially outwardly the outer annular portions and a longitudinal force acting on the seal element in the opposite direction tends to deform theother annular portions radially inwardly.

Another object is to provide a swab seal element wherein the resistances of the longitudinally aligned an- ICC nular portions to radial expansion increase progressively whereby the annular portions are progressively expanded outwardly into sealing engagement with the well flow conductor as the load on the swab increases.

Still another object is to provide a swab seal element wherein the thicknesses of the longitudinal portions increase progressively downwardly, the top annular portion being of narrow width and being most easily expanded and deformed into sealing engagement with the well flow conductor by the fluid load imposed thereon, the other annular portions being of progressively greater width and being progressively and sequentially expanded outwardly into sealing engagement with the well flow conductors as the fluid load on the swab increases.

A further object is to provide a seal element wherein the radial widths of the longitudinally aligned annular portions decrease progressively, the top portion being of greatest radial width and being most easily expanded and deformed into sealing engagement with the well flow conductor by the load imposed thereon, the other annular portions being of progressively smaller radial widths and being progressively and sequentially expanded outwardly into sealing engagement with the well flow conduct-or as the fluid load on the swab increases.

A still further object is to provide a well swab wherein the outer annular portions of the seal elements are provided by annular longitudinally spaced slits in the seal element.

A still further object is to provide a well swab wherein the annular portions of the resilient elements are provided by helical slits in the seal element.

Another object is to provide a well swab wherein the annular portions of the seal element are formed by slits which incline radially upwardly .and outwardly relative to the longitudinal axis of the swab.

Additional objects and advantages of the invention will be readily apparent from the reading of the following description of a device constructed in accordance with the invention, and reference to the accompanying drawings thereof, wherein:

FIGURE 1 is a vertical, partly sectional view showing a well swab embodying the invention with the seal assembly thereof in its uppermost position as the well swab is moved downwardly in a flow conductor;

FIGURE 2 is a vertical, partly sectional enlarged view of the seal assembly of the well swab illustrated in FIG- URE 1; 7

FIGURE 3 is avertical partly sectional view of a modified form of a seal assembly embodying the invention;

FIGURE 4 is a vertical partly sectional view of still another modified form of the seal assembly; and

FIGURE 5 is a vertical partly sectional view of still another modified form of the seal assembly.

Referring now to the drawings, the well swab 10 embodying the invention includes a mandrel 11 comprising a rod 12 provided with a plurality of radially outwardly extending longitudinal ribs 13 intermediate its ends, a connector head 14 threaded on the upper end of the rod, and a seat and guide body 15 threaded on the lower end of the rod. The connector head has opposed slots 16 and downwardly facing stop shoulders 17 which extend radially outwardly in opposite directions from the rod. The connector head has an upper reduced threaded por-' tion or stud 18 by means of which the mandrel may be secured to a suitable connector sub 19 of the usual as-v sembly of flexible line tools by means of which the well swab is moved through a well flow conductor C by a flexible wire line. The seat and guide body 15 has a top seat surface 20 and a plurality of longitudinally extending outwardly opening slots 21 which facilitate the annular portions 35a35e.

(3 flow of well fluids past the seat and guide body during longitudinal movement of the swab in a fiow'conductor.

A seal assembly 25 is mounted on the rod for longitudinal movement relative thereto between the connector head and the seat and guide body. The seal assembly includes a rigid tubular support 26 to which is bonded or otherwise secured a tubular seal element 27. Downward movement of the mandrel relative to the seal assembly is limited by the engagement of the stop shoulders 17 of the connector head 14 with the top end shoulder or surface 29 of the tubular support while upward movement of the mandrel relative to the seal assembly is limited by the engagement of the annular seat surface 20 of the seat and guide body with the lower annular seat shoulder 30 of the tubular support. The seal element may have an inwardly extending annular flange 31 which extends below the lower end of the tubularsupport and which is engageable with the seat surface to help provide a seal between the tubular support and the seat surface. When the well swab is moved upwardly in the flow conductor and the'seal assembly is in its lowermost position on the mandrel, the longitudinal passage 33 of thetubular support is thus closed due to the sealing engagement of the seat shoulders or

surfaces

20 and 30. The ribs 13 of the rod engage the internal surfaces of the tubular support to guide its movement on the rod and at the same time provide longitudinal passages'34 between the tubularsupport and the rod so that during downward movement of the well swab through a flow conductor fluid may flow through the seal assembly.

The seal element 27 has a plurality of longitudinally aligned annular outer portions 35a-35e which are defined and formed by annular external slits 3611-3611. The seal element may be molded on the tubular support as a solid tubular body and then slit at longitudinally spaced locations by an suitable knife means to form the outer The slits 36a-36d extend radially upwardly, for example, at an angle of 75 degrees from the longitudinal axis of the tubular support. The bottom'outer portion 352' has a downwardly and inwardly inclined bottom shoulder 37 while the top surface 38 of the top outer annular portion 35a extends radially outwardly and upwardly. The bottom surface of the top annular portion, the top surface of the bottom annular portion 35c and the top and bottom surfaces of the intermediate annular'portions 35b, 35c and 35d are thus parallel to one another and adjacent surfaces of adjacent outer portions abut one another since the cutting of the resilient seal element does not remove any of the substance of the seal element. V g g The outer annular portions 35a-35e are longitudinally aligned and increase in length or longitudinal width in accordance with their positions from the top of the assembly so that the top outer annular portion is of smallest longitudinal width and is more easily compressed and expanded radially outwardly by a downwardly acting longitudinal force acting thereon than the next lower annular outer portion 35b, the outer portion 35b is more easily expanded radially outwardly than the next lower outer portion 35c, and so on. Each annular outer portion helps support outer portions thereabove against downward deflection since adjacent radial surfaces of adjacent outer portions abut one another.

The external diameter of the seal element 27 is preferably equal to or slightly less than the internal diameter of the well flow conductor in which it is to be used in order that it may be moved relatively easily downwardly in the flow conductor. The upward inclination of the outer annular portions thereof facilitates their upward and inward deformation relative to the tubular support as the outer surfaces of the annular outer portions engage the internal surfaces of the fiow conductor during downward movement ofthe seal assembly in a well fiow conductor. Conversely, when the seal assembly is moved a is moved downwardly in the flow conductor tofacilitate;

upwardly, the frictional engagement of the outer surfaces of the annular portions tends to cause them to move downwardly and therefore outwardly and into engagement with the internal surfaces of the wellflow conductor.

In use, the well swab is movable longitudinally in a 7 wardly through the well flow conductor by gravity. and

overcomes any friction between the seal element and the internal surfaces of the flow conductor tending to resist such downward movement of the well swab. During downward movement of the well swab through the. flow conductor, the mandrel is in its lowermost position relative to theseal assembly 25 since the external surfaces J of the resilient seal element 27 frictionally engage the internal surfaces of the flow conductor'and tend to hold the seal'assembly against downward movement in the flow conductor. During such downward movement, the

longitudinal passage 33 of the tubular support 26 is open since only the stop shoulders 17 of the connector head 14 engage the top end shoulder 29 of the'tubular support.

Liquids present in the flow conductor may therefore flow through the longitudinal passage as the well swab such downward movement. The upward and outward inclination of the outer annular portions 35a-35e also facilitates downward movement of the well swab through the flow conductor since the annular portions may flex upwardly and inwardly as requireclto pass any internal obstructions of the well flow conductor upon their engagement therewith.

When an upward movement is imparted to the'wire line a by means of which the well swab has been lowered through the flow conductor, the mandrel 11'is pulled upwardly until the annular seat or shoulder 30 of the tubular support is engaged by the beveled seat surface 20 of the seat and guide body 15 whereupon the passage33 of the tubular support is closed at its lower end. During such initial upward movement of the mandrel, the seal assembly is held against upward movement both by gravity and by the frictional engagment of the seal element with the internal surfaces of the flow conductor. Once the seat surface 20 has engaged the seat 30 0f the tubular support, further upward movement imparted to the mandrel also results in upward movement of the seal'assembly and any liquids trapped above the well swab are now moved upwardly in the flow conductor by the well swab. The downwardly acting force exerted on the seal element by such slug or column of liquids first cornpresses and expands the top annular portion 35a radially outwardly into sealing engagement with the internal surfaces of the flow conductor since downward flexing of the top annular portion is resisted by the engagement of its bottom surface with the top surface of the next which is in turn supported by the third outer annular portion 350 flexes downwardly, the next lower annular portion 350 is also compressed and expanded outwardly into sealing engagement with the internal surfaces of the flow conductor. Similarly the second lowest outer annular portion 35b and finally the bottom portion 35a will be compressed and expanded radially outwardly into sealing engagement with the well flow conductor as the liquid load is increased. Since the resistances of the outer portions to downward flexing and compression increase progressively due to their greater longitudinal widths or lengths, progressively greater increases in the liquid load are required to progressively cause successively lower outer annular portions to be expanded radially outwardly.

Only such number of outer annular portions is held in sealing engagement with the internal surfaces of the flow conductor as is required to lift the liquids in the flow conductor. This decreases wear of the seal element since if the load is light, only the relatively easily expanded top annular portion 35a sealingly engages the internal surfaces of the flow conductor and is thus abraded and worn during upward movement. It will be noted that each of the outer annular portions supports the outer annular portions thereabove against downward deformation so that the well swab will never dump the liquid load which could occur if adjacent outer annular portions were spaced from one another.

If the external diameter of the seal element is slightly smaller than the internal diameter of the well flow conductor, upward movement of the well swab when liquid is present in the flow conductor above the well swab creates a pressure differential across the seal element which expands the top annular portion 35a. Once the top annular portion 35a is expanded into sealing engagement with the flow conductor, the liquid load holds as many of the outer annular portions in sealing engagement with the internal surfaces of the flow conductor as is necessary to support the liquid load being moved by the well swab.

When the uppermost annular portions abrade during continued use of the well swab and are worn away to a degree that they can no longer efiiciently sealingly engage the internal surfaces of the flow conductor, the next lower outer annular portions of the seal element are progressively and successively expanded radially outwardly into sealing engagement with the well flow conductor. It will now be apparent that since only such number of the annular portions are expanded radially outwardly and sealingly engage the flow conductor as is required-by the liquid load being lifted by the swab, the useful life of the seal element is much greater than if the full longitudinal width of the seal element were held in sealing engagement with the internal surfaces. ofthe flow conductor regardless of the magnitude of the liquid load beinglifted thereby. For example, if the load is very light only the top annular ring 35a is held in sealing engagement with the flow conductor and the abrasion and wear of the other lower annular portions is minimized. As the liquid load progressively is increased the next outer lower annular portions are progressively and successively expanded into sealing engagement.

Referring now to FIGURE 3 of the drawings, the modified seal assembly 125 is substantially similar to the seal assembly 25 and accordingly its various elements have been provided with the same reference numerals, to which the prefix 1 has been added, as the corresponding elements of the seal assembly 25. The tubular support 126 of the seal assembly 125 may have somewhat greater length than the tubular resilient seal element 127 so that its upper portion projects a substantial distance above the top surface 138 of the seal element. The slits 136a136e extend radially outwardly and upwardly at an angle of 60 degrees from the longitudinal axis of the seal assembly, instead of at an angle of 75 degrees as the slits 36a- 36d of the seal assembly 25. Due to this difference in their angular positioning, the annular portions 135a-135f defined and formed by the slits 136a136e are more easily compressed and expanded radially outwardly than the corresponding outer annular portions 35a35e of the seal assembly 25. The top surface of the resilient seal element 125 is provided with an annularly upwardly facing recess 139 which facilitates the radial outwardly expansion of the top annular portion 135a and its downward deflection.

6 The top annular outer portion a also has an upwardly and inwardly beveled shoulder 14% to facilitate the upward movement of the seal assembly past downwardly facing obstructions of the flow conductor.

Referring now to FIGURE 4 of the drawing, the seal assembly includes a tubular support 151 whose bottom annular edge shoulder or seat 152 is engageable with the seat surface 20 of the seat and guide body 15 of the mandrel 11 to close the lower end of the longitudinal passage 153 of the tubular support. A resilient element 154 molded or otherwise rigidly secured to and about the tubular support is provided with a plurality of longitudinal annular portions 15511-155n by a continuous helical cut or slit 156. Full spiral portions 156a-156m of the slit define the annular portions 155a155n. Each annular portion is therefore one coil of a spiral. The radial depth of the helical slit 156 decreases gradually from top to bottom, the radial widths of the outer annular portions 155a-155n decreasing downwardly in order that each outer annular portion be of greater radial width than the next adjacent lower portion and thus be more easily moved and expanded radially outwardly and deflected longitudinally downwardly than the next adjacent lower annular portion.

It will be apparent that the seal assembly 150 is positioned on the mandrel 11 in the same manner as the seal assembly 25 and will function in the same manner to lift a liquid load in a flow conductor when the well swab is moved upwardly therein. The number of outer annular portions 15511-15511 held in sealing engagement with the external surfaces of the flow conductor varies in accordance with the liquid load being lifted by the swab.

Referring now to FIGURE 5, the seal assembly is similar to the seal assembly 154 having a tubular support 176 whose bottom annular edge shoulder or seat 177 is engageable with the seat surface 20 of the seat and guide body 15 when the seal assembly is positioned on the mandrel 11 to close the lower end of the passage 178 thereof.

The tubular resilient seal element 179 is molded or bonded on the tubular support 176 and has longitudinally aligned annular portions 130a-18iln defined and formed by a helical cut or slit 181. Complete turns 181a181m of the slit 181 thus define and form the annular portions ISM-18012. The slit 181 has an outer section 183 which inclines inwardly and downwardly, an intermediate section 184 which inclines inwardly and downwardly at a greater angle relative to the longitudinal axis of the tubular support than the outer section, and an inner section 185 which extends inwardly and downwardly at substantially the same angle as the outer section 183 so that each of the outer annular portions has a somewhat concave top surface which facilitates their radial expansion and downward deflection. The slit 181 decreases in radial depth or width so that the lowermost outer annular portions are of lesser radial width than the uppermost. Each outer annular portion is more easily radially expanded and deflected longitudinally downwardly than the next adjacent lower portion.

It will be apparent that if desired the outer annular portion of the

resilient elements

27 and 127 which are defined and formed by longitudinally spaced annular cuts or slits may he of equal longitudinal widths if each slit is of lesser depth or radial width than the next lower slit.

It will now be seen that in each form of the well swab embodying the invention, the sealing element has longitudinally alinged outer annular portions or lips individually expasible into sealing engagement with a well flow conductor, such outer annular portions being defined and fonmed by longitudinally spaced annular slits in the case of the seal assemblies 25 and 125 and in the case of the

well swab assemblies

150 and 175 by a continuous helical external slit.

It will further be seen that the resistances of the longitudinally aligned annular portions to radial expansion and downward :longitudinal deflection increase progressively as their longitudinal positions whereby the annular portions are progressively expanded outwardly into sealing engagement with the well flow conductor as the load on the :seal element increases. It will further be seen that each outer annular portion supports the annular portions disposed thereabove to cause the radial expansion of the upper annular portions thereabove as the downward force is exerted on the upper end of the seal element by a liquid load before such outer annular portion is itself expanded.

It will also be apparent that resistances to radial ex- I pansion and deformation of such annular outer portions of the seal elements may be varied by varying the conformation of the upper surfaces of the outer annular portions and'by varying the angle at which the outer or lip portions extend radially outwardly and upwardly.

It will be apparent that the angle of the outer annular portions may be varied as desired, it being found that in a seal element of usual natural or synthetic rubber compositions the outer annular portions should preferably extend at an angle of between 60 to 80 degrees from the longitudinal axis. a

The foregoing description of the invention is explanatory only, and changes in the details of the construction illustrated may be made by those skilled in the art, Within the scope of the appended claims, without departing'frorn the spirit of the invention.

What is claimed and desired to be secured by Letters Patent is: V

1. A sealassembly for a well swab including: a tubular support having a longitudinal passage and a resilient seal element disposed about and secured to said tubular support, said seal element having a plurality of outer longitudinally aligned annular portions extending outwardly and upwardly at an angle from the longitudinal said outer annular portions increasing progressively in longitudinal width in accordance with their longitudinal and upwardly at an angle from the longitudinal axis of said tubular support, adjacent outer annular portions hav' ing abutting adjacent surfaces whereby downward longitudinal deflection of each outer annular portion is reresisted by a lower adjacent outer portion, said outer portions being expandable radially outwardly when subjected to a downward force exerted thereon, each outer annular portion being expandable by a force smaller than that required to expand the next lower adjacent outer portion, said outerannularportions decreasing progressively in radial width in accordance with their longitudinal locations, each of said outer annular portions being of smaller radial width than the next upper adjacent outer portion. 7 a

3. A seal assembly fora well swabincluding: a tubular support having a longitudinal passage and a resilient seal element disposed about and secured to said tubular support, said seal element having a plurality of longitu dinally aligned outer annular portions extending outwardly and upwardly at an angle from the longitudinal axis of said tubular support, said seal element having a helical slit defining said outer annular portions, said helical slit having an outer section, an inner section and a interme diate section, said outer and inner 'section extending upwardly at smaller angles from the longitudinal axis .of the, tubular support than the intermediate section, adjacent outer annular portions having abutting adjacent surfaces whereby longitudinal deflection ofieach outerannular portion is resisted by an adjacent lower outer portion;

References Cited bythe Examiner UNITED STATES PATENTS V 2,975,722 3/1961' Webber ;103 -225 3,023,062 2/1962 Waldrop 271-205 3,146,725 9/1964 Harris 277 20s LAVERNE: D. *GEIGER, Primary Examiner. D. MASSENBERG, Assistant Examiner.

Claims

1. A SEAL ASSEMBLY FOR A WELL SWAB INCLUDING: A TUBULAR SUPPORT HAVING A LONGITUDINAL PASSAGE AND A RESILIENT SEAL ELEMENT DISPOSED ABOUT AND SECURED TO SAID TUBULAR SUPPORT, SAID SEAL ELEMENT HAVING A PLURALITY OF OUTER LONGITUDINALLY ALIGNED ANNULAR PORTIONS EXTENDING OUTWARDLY AND UPWARDLY AT AN ANGLE FROM THE LONGITUDINALLY AXIS OF SAID TUBULAR SUPPORT, ADJACENT OUTER ANNULAR PORTIONS HAVING ABUTTING ADJACENT SURFACES WHEREBY LONGITUDINAL DEFLECTION OF EACH OUTER ANNULAR PORTION IS RESISTED BY AN ADJACENT LOWER OUTER PORTION, SAID OUTER PORTIONS BEING EXPANDABLE RADIALLY OUTWARDLY WHEN SUBJECTED TO A DOWNWARD FORCE EXERTED THEREON, EACH OUTER ANNULAR PORTION BEING EXPANDABLE BY A FORCE SMALLER THAN THAT REQUIRED TO EXPAND THE NEXT LOWER ADJACENT OUTER PORTION, SAID OUTER ANNULAR PORTIONS INCREASING PROGRESSIVELY IN LONGITUDINAL WIDTH IN ACCORDANCE WITH THEIR LONGITUDINAL LOCATIONS, EACH OUTER ANNULAR PORTION BEING OF SMALLER LONGITUDINAL WIDTH THAN THE NEXT LOWER ADJACENT ANNULAR PORTION.