US3537519A - Paraffin scraper - Google Patents

Description

United States Patent 72 inventor Travis a. Long Arlington, Texas [21} Appl. No. 788,478 [22] Filed Jan. 2, 1969 [45] Patented Nov. 3, 1970 I [73] Assignee Oil States Rubber Co.

Arlington, Texas a corporation of Texas [54] PARAFFIN SCRAPER 6 Claims, 11 Drawing Figs.

[52] US. Cl. 166/175, 166/ l 76 [51] Int. Cl. E2lb 37/02 [50] Field of Search 166/170, 175, 176; 308/4A [56] References Cited UNITED STATES PATENTS Primary Examiner-David H. Brown Attorney-Schley and Schley ABSTRACT: A migratory paraffin scraper of generally cylindrical configuration for removing deposits from oil well tubing and sucker rods and having a pair of coacting longitudinal sections slidably connected together for relative longitudinal movement to open and close a longitudinal flow passage therethrough. Opening of the passage permits the scraper to drop relative to the rod and closing of said passage permits lifting of said scraper by the well fluids whereby said scraper continuously travels upwardly and downwardly throughout the length of a sucker rod during reciprocation of the rod. The scraper also functions as a rod guide.

Patented Nov. 3, 1970 Shoot l of 2 INVENTOR. TI'OVIS 8. Long ATTOR NHYS Patented Nov. 3, 1970 Sheet INVENTOR. Trovis B. Long fiw ATTORNEYS 1 rxnxrsnv SCRAPER BACKGROUND OF THE INVENTION SUMMARY OF THE INVENTION A novel migratoryparaffin scraper for removing deposits from the tubing and sucker rods of pumping oil wells as well as a guide for preventing the rod upon which it is mounted from wearing against said tubing. The scraper includes a pair of coacting longitudinal members having elongate bodies, of relatively small transverse dimensions, adapted to engage a sucker rod in opposed, spaced relationship. One of the bodies is of greater length and has enlarged, substantially U-shaped end and medial portions or yokes for engaging around the rod and overlapping the other, shorter body and its enlarged, U- shaped end portions or yokes to provide a generally cylindrical configuration substantially complementary to the well tubing. The medial yoke of the longer body slidably engages the shorter body, while the end yokes of said shorter body slidably engage said longer body above and below said medial yoke to permit relative reciprocation of said longer body. Coacting, longitudinal, guide ribs and grooves are provided for connecting these medial andcnd yokes to the respective bodies, and longitudinal recesses or slots extend through the exteriors of said yokes to provide a longitudinal flow passage through the scraper. The slots of the upper end yoke are offset relative to the slots of the medial yoke whereby the flow passage is closed when said'medial yoke engages said upper end yoke in the uppermost position of the longer member relative to the shorter member. The scraper travels upwardly relative to the sucker rod when the passage is closed and travels relatively downward upon opening of said passage. The end yokes of the longer member onset with stop means at the ends of the rod to shift said longer member relative to the shorter member and 1 reverse the travel of the scraper.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevational view of a paraffin scraper constructed in accordance with the invention and mounted on a sucker rod, shown broken, for reciprocation within a well tub ing, shown in section, the scraper being in closed position and moving upwardly,

FIG. 2 is a view, similar to FIG. 1, showing the paraffin scraper in open position and moving downwardly,

FIG. 3 is a side elevational view of the scraper, in an opened position, and a portion of the sucker rod,

FIGS. 4, 5, 6 and 7 are horizontal. cross-sectional views taken on the respective lines 4-4, 5-5, 66 and 7-7 of FIG. 3,

FIG. 8 is a horizontal,cross-sectional view taken on the line 88 of FIG. 2,

FIG. 9 is an exploded view of the scraper and a portion of the rod,

FIG. 10 is a perspective view of the scraper in closed position, a portion of the rod being shown in broken lines, and

FIG. 11 is a view, similar to FIG. 10, showing the scraper in open position.

DESCRIPTION OF THE PREFERRED EMBODIMENT In the drawings, the numeral 1 designates a paraffin scraper embodying the principles of the invention and mounted on a conventional sucker rod 2 for relative reciprocal movement in an oil well tubing 3. The sucker rod 2 forms a part of a string (not shown) and has the usual enlargements or upsets 4 on its ends which may be'utilized as stops to actuate the paraffin scraper 1. It is preferable, however, to employ rod guides or stop elements 5 for this purpose, the stop elements being in the form of resilient, split collars frictionally engaged around the rod adjacent its upsets 4 and having wide gaps or flow passages 6 (FIG. 8) extending axially therethrough. It is noted that the scraper is adapted to undergo reciprocation relative to the rod as well as to the tubing 3.

The paraffin scraper 1 includes a pair of longitudinal members or sections'I and 8 which are adapted to couct in opening and closing an axial flow passage extending through said scraper and which are formed of slightly resilient material, such as hard rubber or plastic, so as to be capable of ready as sembly on the sucker rod 2. The member 7 is of greater length than the member 8 so as to extend thereabove and therebelow and has an elongate body 9 of relatively small transverse dimensions except forits enlarged end and medial portions 10 and 11 which are in the form ofhorizontal, laterally-projecting yokes. An internal, continuous surface 12, which is concavely arcuate in cross section, is coextensive with the body 9 and its end portions or yokes 10 for complementary engagement with the rod as shown in FIGS. 47, while the exterior of said body is convexly arcuate in cross section so as to be complementary to the bore of the tubing 3. In order to facilitate reciprocation of the scraper past obstructions, such as the joints (not shown) of the tubing, the end yokes of the body have their exteriors offset inwardly so as to be of reduced size and are connected to the remainder of the body exterior by bevelled surfaces 13. As shown in FIGS. 4 and 6, the lateral or side surfaces 14 of the body 9. are flat and parallel and have coextensive, upright, parallel guide ribs 15 (FIG. 9) between the end and medial yokes l0 and 11 of said bodyfor coacting with the member 8. Preferably, the guide ribs 15 are trapezoidal in cross section and closer to the inner than the outer longitudinal margins of the lateral surfaces.

Each of the end portions or yokes 10 is identical and has a substantially semiannular or U-shaped configuration, as

'shown in FIGS. 7, 10 and 11, so as to provide a semicylindrical bore 16 of which the internal surface 12 forms a part. A pair of opposed, flat, parallel surfaces 17 extend from the bore 16 to provide an upright, coextensive, wide slot diametrically opposed to the body 9. Each of the slot surfaces 17 may have an upright, coextensive groove 18, trapezoidal in cross section, adjacent its outer longitudinal margin for increasing the flexibility of the outer portion of each yoke. Although the medial portion or yoke 11 of the body is substantially semiannular or U-shaped in cross section and has a semicylindrical bore 19, opposed, flat parallcl surfaces 20 and upright, coextensive grooves 21 which are substantially identical to the bore 16, slot surfaces 17 and grooves 18 of each end yoke 10, as best shown in FIG. 5, it is of greater axial length and has an exter nal diameter substantially equal to the internal diameter of the tubing 3. In addition, a pair of diametrically-opposed, coextensive recesses or slots 22 extends axially of the exterior of the medial yoke with one of the slots being in spaced contiguity to the outer end of said yoke and the other slot adjacent the bight of the yoke.

The shorter member 8 of the paraffin scraper 1 has a body 23 which is identical to the body 9 of the longer member 7 except for being of shorter length and having only enlarged end portions or yokes 24 (FIGS. 9-11). The body 23 and yokes 24 are opposed to the body and yokes l0 and 11 whereby the yokes of each member overlap the body and yokes of the other member when the scraper is assembled. Similar internal and lateral surfaces 25 and 26 and guide ribs 27 are formed on the body 23 (FIG. 5). The coextensive, lateral surface 25 is complementary to the sucker rod 2, while the flat, lateral surfaces 26 and their ribs 27 are complementary to and slidably engage the slot surfaces 20 and grooves 21 of the medial yoke 11 of the other body when the members are assembled. It is noted that the end portions or yokes 24 of the body are similar to the yoke 11 and have similar substantially semiannular or U-shaped configurations as well as similar semicylindrical bores 28, opposed slot surfaces 29 and upright, coextensive grooves 30. As shown-in FIGS. 4 and 6, the surfaces 29 and grooves 30 are complementary to and slidably engage the flat, lateral surfaces 14 and guide ribs 15 of the body 9 when the members 7 and 8 are assembled. An external, bevelled surface 31, similar to the bevelled surfaces 13, is provided at the upper margin of the upper yoke and at the lower margin of the lower yoke to facilitate reciprocation of the scraper past obstructions. Preferably, the yokes 24 are of greater axial length than the yoke 11. Pairs of diametrically opposed recesses or slots 32 and 33, similar to the recesses 22 of the yoke 11, are coextensive with the exteriors of the upper and lower yokes 24, the slots 33 of the lower yoke being aligned with said slots 22 and the slots 32 of the upper yoke being offset at right angles thereto (FIGS. 1-3, 10 and 11).

Manifestly, the recesses or slots 22, 32 and 33 coact to provide a longitudinal flow passage through the paraffin scraper 1 when the longer member 7 moves downwardly relative to the shorter member 8 as shown in FIGS. 2, 3 and 11. In the uppermost position of the longer member shown in FIGS. 1 and 10, the slots 33 of the upper yoke 24 are closed by the medial yoke and the slots 22 of said medial yoke are closed by said upper yoke to prevent flow through the passage of the scraper. It is noted that the internal surfaces 12 and 28 of the bodies 7 and 23 coact with the semicylindrical bores 16, 19 and 28 to provide a cylindrical bore of sufficient diameter to permit reciprocable movement of the paraffin scraper relative to the sucker rod. Also, the external diameter of the scraper is sufficiently less than the internal diameter of the tubing to permit relative reciprocation of said scraper. As is well known, well fluids contain paraffin and similar substances which tend to separate therefrom and deposit on the internal surface of the tubing as well as on the sucker rods whereby it is necessary to remove the accumulation in order to prevent undue restriction of the flow area. Also, wells are seldom, if ever, straight or vertical and may be slanted or spiralled whereby the string of sucker rods ofa well pump engages and wears against the tubing wall. Accordingly, it is customary to mount guides and paraffin scrapers on the rods so as to center the same relative to the tubing as well as remove deposits of excessive thickness, with the scrapers being employed in the zones of said deposits.

In addition to functioning as guides, it is readily apparent that the ribs and 27 coact with the grooves 18, 21 and-28 to slidably connect the members 7 and 8 together around the sucker rod. Since the external diameter of the paraffin scraper is only slightly smaller than the internal diameter of the tubing 3 and since the bore of said scraper is of only slightly greater diameter than the sucker rod 2, said scraper substantially closes the annulus between said rod and tubing. When the scraper is installed, the shorter member is in its upper position relative to the longer member (FIGS. 2 and 11) whereby the longitudinal flow passage of said scraper is open and permits settling thereof to the lower end of the rod adjacent the lower guides during lowering of the sucker rod string in the tubing. Upon upward reciprocation of the red, the scraper tends to remain stationary due to its open passage until the guide strikes the lower yoke 10 of the longer body 9 and lifts the member 7 relative to the member 8. As shown in FIGS. 1 and 10, this relative upward movement engages the medial yoke 11 of the longer body with the upper yoke 24 of the shorter body 23 so as to close the slots 32 of said upper jaw as well as the slots 22 of said medial yoke and prevent flow through the passage of the scraper. Due to its closed condition and engagement with the rod guide, the scraper moves upwardly with the rod and remains stationary during the downstroke of said rod. This relative downward movement of the rod scrapes excessive deposits therefrom. Upon subsequent upstrokes of the rod, the well fluids lift the scraper until the upper end yoke 10 of the body 9 engages the upper rod guide 5. Since the annulus between the rod and tubing is substantially filled by the closed scraper, excessive paraffin is scraped from the tubing wall during upward movement of said scraper and is suspended in the well fluids so as to be carried to the surface.

Manifestly, a number of upstrokes of the rod are required to complete the upward travel of the paraffin scraper. Upon the arresting of this travel, the subsequent downstroke of the rod forces the longer member 7 downwardly relative to the shorter member 8 so as to move the medial yoke 11 of the longer body 9 out of engagement with the upper yoke 24 of the shorter body 23 and permit flow through the slots 33, 32 and 22. During subsequent reciprocation of the rod, the scraper falls or settles until the lower yoke 10 of the longer body strikes the lower rod guide and the longer member is lifted relative to the shorter member by the upstroke of said rod to again close the flow passage of the scraper. The weight of the scraper is suffi cient to permit it to drop through the well fluids and this descent continues irrespective of the direction of movement of the rod. It is readily apparent that the opening and closing of its flow passage permits the paraffin scraper to travel downwardly and upwardly throughout the length of the rod during reciprocation of the latter and that the relative downward movement of said scraper wipes deposits from said rod. Of course, deposits are removed from a portion of the rod upon downward movement of said rod relative to the scraper; however, primary scraping of said rod occurs during downward travel of said scraper. The latter travel is continuous, while upward travel of the scraper is intermittent or in stages. Except for opening and closing the flow passage of the scraper at the ends of its travel to reverse the direction thereof, the reciprocation of the rod has no effect upon such travel. Again, it is noted that the upsets 4 of the sucker rod 2 may be used in place of the rod guides S to open and close the flow passage of the scraper. Due to the yokes of each member overlapping the body and yokes of the other member, said yokes coact to provide a generally cylindrical configuration which is interrupted by recesses or slots whereby the paraffin scraper also functions as a rod guide.

Iclaim:

l. A migratory paraffin scraper adapted to be mounted on sucker rod having stops at its ends for removing deposits from the rod and well tubing including:

a pair of coacting relatively reciprocable members having elongate bodies extending longitudinally of the sucker rod in opposed spaced relationship;

one of the members and its body being of greater length and having a medial yoke projecting laterally from the body so as to overlap the body of the other member;

said other member and its body being of shorter length and having laterally projecting end yokes overlapping the longer body and medial yoke of the longer member above and below the medial yoke;

the yokes having arcuate interiors complementary to the rod for slidable sealing engagement therewith and semicylindrical exteriors coacting to provide a generally cylindrical configuration substantially complementary to the well tubing for slidable sealing engagement therewith;

the bodies and the interiors of said yokes having complementary surfaces for slidable sealing engagement with one another;

the exteriors of said yokes having coextensive longitudinal recesses to provide a longitudinal flow passage;

the recesses of the upper end and medial yokes being offset relative to one another whereby the passage is closed and the paraffin scraper travels upwardly of the rod when said yokes are in engagement and whereby said passage is opened and said scraper travels downwardly of the rod when said yokes are disengaged; and

the ends of said longer member projecting above andbelow said end yokes of said shorter member for engagement with the rod stops to reciprocate said longer member relative to said shorter member and reverse the travel of said scraper.

2. A migratory paraffin scraper as defined in claim 1 includ' ing coacting means on the complementary surfaces of the bodies and the interiors of the yokes for slidably connecting the members.

3. A migratory paraffin scraper as defined in claim 1 including coacting guide ribs and grooves extending longitudinally of the complementary surfaces of the bodies and the interiors of the yokes for slidably connecting the members.

4. A migratory paraffin scraper as defined in claim 1 including a yoke projecting laterally from each end of the longer member for slidably engaging around the sucker rod and overlapping the adjacent end yoke of the shorter member as well as for engaging the rod stops.

5. A migratory parafiin scraper as defined in claim I wherein the bodies of the member have surfaces complementary to the sucker rod' and well tubing for slidably engagement therewith.

6. A migratory paraffin scraper as defined in claim 1 wherein the bodies of the members have small transverse dimensions relative to the diameter of the well tubing so as to coact with the recesses of the yoke exteriors in forming the longitudinal flow passage.

Images