US3330359A - Self-reversing scraper - Google Patents

Description

July 11, 1967 w. F. WARD SELF-REVERSING SCRAPER 2 Sheets-Sheet l Filed Sept. 20, 1965 INVENTOR WARREN F. WARD ATTORNEYS July 11, 1967 w. F. WARD 3,330,359

SELF-REVERSING SCRAPER med sept. zo, 1965 2 sheets-sheet 2 INVENTOR WARREN F. WARD ATTORNEYS United States Patent Olice 3,333,359 Patented July 11, 1967 3,330,359 SELF-REVERSING SCRAPER Warren F. Ward, 4419 Rawling St., Dallas, Tex. 75219 Filed Sept. 20, 1965, Ser. No. 488,452 Claims. (Cl. 166-175) ABSTRACT OF THE DISCLOSURE A migratory parathn scraper loosely surrounding a sucker rod and freely slidable in a tubing string and having a body transversely divided into upper and lower portions, each having at least one slot through its side wall through which the sucker rod can be snapped into the central bore of the body, and the slots serving as iluid bypass passageways. An actuator rod is fixed in the lower body portion out of registry with its slot, or slots, and extends upwardly through a slot in the upper body portion and is bent to surround the sucker rod above the latter. The actuator holds the slots in the two body portions out of mutual registry. Detent means are provided to releasably hold the body portions together when mated at their transverse surfaces, thereby blocking the flow of uid through the slots and causing the scraper to rise on the sucker rod, but the detent means are released when the upper end of the actuator strikes an abutment on the sucker rod, thereby causing the body portions to separate and permit ow of uid througth the slots, resulting in descent of the scraper portions on the sucker rod until the lower one strikes an abutment and the two portions re-mate.

This invention relates to self-cleaning oil well parain Scrapers of the type which surround a sucker rod and migrate up and down substantially the entire length thereof as the well is pumped, and more particularly the invention relates to the improvement of parain Scrapers by providing a novel valving action which automatically operates upon contact with the sucker rod upsets to cause the scraper to rise when it reaches the bottom upset of the sucker rod and to fall when it reaches the top upset.

It is a principal object of this invention to provide a parain scraper capable of migrating up and down a length of sucker rod as it reciprocates in a Well for the purpose of cleaning parain deposits not only from the sucker rod but also from the adjacent tubing, the direction of migration of the scraper being selectively determined byl automatically-operated valve means cooperating with the downward eiect of gravity and with the upward etect of the rising column of uid in the tubing.

Another important object of the invention is to provide a novel parat-lin scraper combination including a scraper of the type shown generally in Patents 2,604,364 and 2,793,917 and characterized by a body with a longitudinal slot through its side wall communicating with a central bore receiving the sucker rod, and the present novel combination further including valving structure for selectively opening and closing the slot to alter the resistance of the scraper body to the upward ow of iluid therepast, whereby when the valve means is closed the scraper body will present a large resistance to luid tlow causing it to rise in the tubing, and when the valve means is open the body will present a much smaller resistance to flow therepast thereby permitting the force of gravity to cause it to descend in the tubing.

A further important object of the invention is to provide a novel scraper body divided transversely into two portions which have their slots out of registry, so that liquid can pass through them when the two portions are separated but is partly blocked from passing when the two portions are moved together, this combination further including a trip mechanism passing through the slot in one portion of the body and extending longitudinally therebeyond to be fixed in the other portion of the body, so that when the scraper approaches one of the sucker rod upsets, the trip mechanism will contact the latter and will be shifted longtiudinally of said one portion of the body to change the axial position of the other portion of the body with respect thereto and thereby reverse the direction of migration.

Since the present scraper depends upon gravity to cause it to drop downwardly along the sucker rod when the valve means is opened, it is important that the scraper be heavy enough to drop despite the upwardly flowing column of pumped fluid. It is also important that the opening provided by the longitudinal slots in the two portions of the body be large enough to by-pass the tiuid to make it possible for the scraper to drop. The scraper body portions can be made of metal, rubber, or plastic, such as nylon, although in the latter case it may be necessary to add weight to the plastic body to help it fall in the tubing. The outside diameter of the body portions should be somewhat less than the tubing, and the axial bore therethrough should be somewhat greater in diameter than the sucker rod. Experiments on Working models have shown that a body having a 3A central bore Works well on a 5/s" diameter sucker rod. The width of the longitudinal slots should be great enough not only to -by-pass the well iluid how, but also great enough to permit the insertion of the sucker rod into the bore through the slot by forcing it therethrough with a snapping action.

Another object of the invention is to provide novel yieldable detent means serving to hold the body portions together when they are mated in closed position, the detent means in one embodiment comprising magnet means, and in another embodiment comprising a dart-shaped member mounted on an actuator rod which comprises part of the trip mechanism and the member being made of resilient material, such as rubber. This detent member should be a wedging it in the slot Without being so tight as to prevent release therefrom when the trip mechanism is actuated against a sucker-rod upset to drive the two body portions apart.

The edges of the body portions, particularly the edges of the slots, serve to scrape both the sucker rod and the tubing as the body portions travel up and down therewithin. Moreover, there yare several phenomena which contribute to rapid rotation of the scraper during its travel, including the usual circular swirl of the fluid rising within the tubing. This rotation is augmented by tilting one or both slots out of parallel relationship with the axis of the bores so that iiuid iiow through the slanted slots causes deection of the body portions, resulting in a circumferential component of force tending to maintain rotation. At vany rate, the scraper not only travels in a longitudinal direction, it also rotates during this travel so that the edges of the slots act as paraihn cleaning blades slicing the soft paraiiin both from the inner walls of the tubing and from the outer surface of the sucker rod. The actuator rod extending through the slot in said one body portion is a very loose tit therein and tends to lash about during migration to clean the sides of the slot of paran deposits.

It is still another important object of the invention to provide a migratory, valved parain scraper which can be applied onto a standard sucker rod by merely snapping it into place, with the result that there is no need to provide a special sucker rod wherein one of the ends has no fixed upset structure as would be required in some prior art structures to permit a fully cylindrical scraper to be introduced over that end of the rod. The present structure can be snapped onto any standard rod without any alteration of the rod.

The known prior art includes Patent 2,720,925 which shows a cylindrical moving scraper structure which can be introduced over the end of a sucker rod to be actuated by rod-engaging dogs along the length thereof. The mode of operation and the structure thereof is, of course, different from the present invention. The prior art also includes various go-devils in the form of hollow torpedoes which can be introduced into a pipeline, and some of which go-devils have valves which are manipulated by the striking of a stop located inside of the pipeline, but none of these devices would be operative within a tubing string which also has a sucker rod extending through its center. In general, the present structure operates most satisfactorily in wells in which the tubing is relatively straight so that the sucker rods tend to maintain a centered position within the tubing. However, in wells where the bore is not straight, the tendency of the sucker rod to lie against the tubing wall in an off-center position will interfere with free longitudinal movement of the present scrapper. This condition can be corrected in a satisfactory manner by mounting fixed scrapers on each end of the sucker rod, for instance Scrapers of the type shown in Patents 2,604,364, 2,793,917, or others, these Scrapers serving the purpose of holding the sucker rod centered with respect to the tubing wall. Obviously, the present migratory Scrapers can operate between two fixed scrapers or between any other abntments which remain fixed to the sucker rod. Therefore, the operation of this migratory scraper is not limited to abutting against the upset at each end of the rod.

The present disclosure also includes novel specific structures for illustrating practical embodiments of the present invention, these embodiments being described hereinafter in greater detail.

Other objects and advantages of the present invention will become apparent during the following discussion of the drawing, wherein:

FIG. l is a view in prespective showin-g a scraper according to the present invention descending on a sucker rod located within a pump-tubing string, the tubing being broken away to show the scraper assembly approaching the upset at the lower end of the illustrated sucker rod;

FIG. 2 is an elevation view of the structure shown in FIG. 1, but showing the scraper after it has contacted the upset and blocked the slots to provide a closed valving action, thereby causing the scraper to rise within the tubing string;

FIG. 3 is an elevation view similar to FIG. 2, but taken at a location near the upper end of the sucker rod and showing the scraper assembly abutted against the upper upset of the sucker rod, with the result that the body portions have again been separated to provide an open valving action through the slots, thereby adjusting the scraper assembly to commence its descent;

FIG. 4 is a View of an actuatingrrod member;

FIG. 5 is a perspective view of the lower body portion which in the illustrative embodiment of the invention has its slot titled with respect to the axis of its bore;

FIG. 6 is a perspective view of a detent means made of resilient material of such width as to result in compression of the detent means when inserted in the slot of the upper body portion;

FIG. 7 is an elevation view of a first modified form of scrapter according to the present invention; andV FIG. 8 is a perspective view of a second modified form of scraper according to the present invention.

Referring now to the drawings, FIG. 1 shows a sucker rod R disposed within a length of pump tubing T, the latter being shown in cross-section so as to illustrate a migratory parain scraper assembly according to Ythe present invention located within the tubing. FIGS. 1, 2, and 3 show the paran scraper assembly in pro-gressively different positions, as will be described hereinafter. The

sucker rod R is a standard rod having an upset U at each end located adjacent wrench flats W which are in trun located near threaded end portions, all of usual design.

The scraper assembly includes a scraper body divided into two portions 1 and 2, and resembling a design which is generally well-known in the prior art and is characterized by substantially cylindrical body portions having bores 1a and 2a through the center thereof. Since it is necessary that the body portions slide up and down on the sucker rod, the diameter of the bores 1a and 2a are made somewhat greater than the diameter of the sucker rod R between the upsets U. Likewise, the outside diameters of the portions 1 and 2 are made less than the inside diameter of the tubing T so as to permit the body portions to freely migrate within the tubing. The opposite ends of the body portions are chamfered as at 1b and 2b to prevent the body portion from snagging upon irregularities in the tubing. Both body portions have longitudinal slots 1c and 2c extending through their side walls, the slots preferably, although not necessarily, being slightly Vnarrower in width than the diameter of the sucker rod R in the illustrated embodiment, whereby the rod can be forced through the slots and Ventered into the bores 1a and 2a with a snapping action. Either slot, or both slots, Vcan be tilted out-of-parallel relationship with respect to the axis of the bores, and the present illustrative embodiment shows the slot 2c tilted in this manner. The two body portions mate with each other at transverse faces 1d and 2d.

The migratory scraper assembly according to the present invention includes, in combination with the abovedescribed body portions, trip means for selectively opening or blocking the longitudinal passageway provided by the slots 1c and 2c, either separating or mating the two body portions at the faces 1d and 2d as shown in FIGS. 1 and 2, respectively. The trip means includes an actuating rod member 3 having a right-angled lower end '3a and a. ring-shaped upper end 3b, as shown in FIG. 4. The. ringshaped upper end is C-shaped and therefore provides a gap through which the sucker rod R can be passed so as to place the C-shaped portion 3b around the rod R as shown in FIGS. 1, 2, and 3. The actuating member shown in FIG. 4 is further provided with a C-shaped member 4 to which the angled lower end 3a is fixed, for example by welding. The lower body member 2 is made of rubber, or plastic such as nylon, or some other dimensionally stable material, and the members 3a and 4 are embedded in the material as shown in FIG. 5 with the opening in the C-shaped member 4 in registry with the slot 2c of the body portion 2.

FIGS. 1, 2, 3, and 6 illustrate detent means 5 shaped to resemble a dart point and including a central portion 5a in front of a shank portion 5b. This detent means includes two side flukes 5c separated from the shank portion 5b at two undercut locations Sd which make it easier to compress the two ukes 5c toward each other to narrow the width of the detent means 5 when it is inserted in the slot 1c. The detent means 5 is preferably made of a resilient rubber or neoprene and has a bore 5e to receive the rod 3 extending :above the lower body portion 2. The resilient detent means is preferably bonded to the rod 3, and, with proper selection of materials, may even be molded integrally with the lower body portion 2. The actuating rod can be made of stainless steelr to provide adequate strength and resistance to corrosion.

After the member 3 is secured within the detent means 5 and the body portion 2, the latter can then be snapped onto the rod vi-a the slot 2c, and the looped upper end 3b Y of the actuating member 3 can be strained open enoughY to receive the sucker rod R. The actuating rodY 3 will then pass longitudinally through the slot 1c as shown in FIGS. 1, 2, and 3.

FIG. 7 shows a first modified form of scraper 10 which performs in the same general way as the scraper shown in FIG. 1. This modified scraper has upper and lower body portions 11 and 12, respectively, including longitudinal slots 11c and 12e. The actuator rod member is the same as in FIG. 4, and is therefore similarly labeled with reference numerals 3 and 4. 'Ihe detent means 15 is similar to that shown Iin FIG. 6, but is modified to provide bulb-like projections 5p which mate with similarlyshaped grooves 1p near the lower end of the slot 1c when the upper and lower body portions are mated to provide an increased holding power for the detent means.

An additional feature of the modified form of FIG. 7 resides in the outwardly extending ribs 16 molded into circumferential recesses 17 in the upper body portion 11, which ribs are thin enough to be flexible, but stiff enough to provide improved Vwiping action as well as an improved sealing effect between the body portion 11 and the sucker tubing T in which the scraper is intended to migrate.

FIG. 8 shows a second modified form of the invention in which the scraper 20 performs in a manner basically similar to the performance of the Scrapers shown in FIGS. 1 and 7, but in which the detent means comprises magnet means `rather than deformable dart-shaped members. This second modification includes upper and lower body portions 21 and 22, respectively, having longitudinal slots 21C and 22C which are mutually out of alignment so that when the body portions are mated, the slots are blocked to restrict uid ow therethrough. The rod actuator 3, 4 serves the same purpose as Iin the other illustrative forms of the invention. One of the body portions, portion 21 in the illustrative embodiment, has one or more permanent magnets 23 embedded therein, and the other body portion, i.e., 22, has a permeable plate member 24 attached thereto. The plate 24 can be bonded to the body 22 and/or Welded to the rod 3 to hold it in place.

It should be apparent that when the body portions 21 and 22 are united, the magnets 23 will hold the plate 24 with a releasable grip, which can be :adjusted by suitable design so that the impact of the upper end 3b of the actuator against a sucker rod upset U will be sufiicient to break the magnetic grip at the end of the upstroke of the scraper 20, but so that the lower portion 22 fwill not accidentally fall away from the upper portion 21 before such impact.

Referring again to FIGS. 1, 2, and 3, these three figures show a sequence of events occurring during normal operation of the present migratory scraper assembly. In FIG. 1, the scraper is descending toward the upset U at the lower end of the sucker rod R and counter to the flow of fluid travelling in the direction of the arrows F. The lower body portion 2 is separated from the upper portion 1 and is therefore in open position so that the fiuid is free to travel upwardly through the slots 1c and 2c to by-pass enough Huid to permit the assembly to gravitate downwardly. As the assembly drops, eventually the bottom end of the lower body portion 2 will bottom against the upset U, and the body portion 1 will settle downwardly on the detent means 5 until the surfaces 1d and 2d mate, thereby driving the detent means 5 into the slot 1c to assume the closed position shown in FIG. 2. The uid passageway through the slots 1c and 2c are thus blocked respectively by the body portion 2 and by the body portion 1, thereby greatly increasing the resistance of the scraper to the flow of uid therepassed in the direction of the arrow F, with the result that the whole scraper assembly becomes a piston which is buoyed up by the rising fluid F and forced to migrate upwardly on the sucker rod R, thereby scraping parafiin from the outer surface thereof.

Eventually, the wire loop 3b of the actuating member 3 bottoms upon the upset U at the upper end of the sucker rod R as shown in FIG. 3, and upon further upward advance by the body 1, the detent means -5 is dislodged from the slot 1c and the body portions separate, thereby reopening the slot to the position shown in FIG. 1 to by-pass the fluid F through the slots and again re- 6 duce the buoyancy of the body 1 sufficiently so that the force of gravity can cause it to drop until it reaches the lower upset U shown in FIG. l, 4at which time the valviug .action will again function to close the slots and to re-insert the detent means 5 into the slot 1c.

As is well-known to those skilled in the art, the fluid Within the tubing T rotates during the pumping operation, and this has a tendency to rotate the scraper so as to increase the paraffin scraping efficiency by making the inside and outside edges of the slots 1c and 2c function as paraffin scraping edges thereby improving the cleaning action of the body both upon the sucker rod R and on the inner surfaces of the tubing T. Although the slots can be oriented parallel with the axis of the bores, a preferred structure of the body portions provides one or more of the slots skewed slightly so that it is no longer parallel with said axis,- thereby adding a further rotative component.

The present invention is not to be limited to the exact forms shown in the drawing, for obviously changes may be made therein within the scope of the following claims.

I claim:

1. In oil well equipment, a parafn scraper assembly for migrating up and down on a s-ucker rod having spaced abutments thereon and located within a surrounding tubing string, comprising:

(a) upper and lower body portions freely slidable Within said tubing string and having longitudinal bores therethrough sized to freely pass the sucker rod, said portions having longitudinal slots in their side walls extending the full length of the body portion, and the adjacent ends of the portions having matching transverse surfaces at which they can mutually mate;

(b) means for maintaining the slots in the body portions out of mutual alignment;

(c) actuator means attached to one portion and extending beyond the other portion and operative to separate the body portions when the actuator means strikes an abutment; and

(d) detent means carried by said portions for yieldably holding the portions in mated relation.

2. In a scraper as set forth in claim 1, said actuator means comprising a rod having one end fixed in the lower body portion and the other end terminating above the yupper body portion and partly surrounding the sucker rod.

3. In a scraper as set forth in claim 1, the slot in t-he lower body portion being skewed at an acute angle with respect to the axis of the bore therethrough.

4. In a scraper as set forth in claim 1, said actuator means comprising a -rod having one end fixed in the lower body portion and extending through the slot in the upper body portion, and said detent means comprising a resilient dart-shaped plug fixed to the lower portion at the rod and resiliently distortable to frictionally grip said slot when entered thereinto.

5. In a scraper as set forth in claim 1, said detent means comprising magnet means embedded in the body portions adjacent said transverse surfaces mutually attracting the portions when mated.

6. In oil Well equipment, a paraffin scraper assembly for migrating up and down on a sucker rod within a surrounding tubing string, comprising:

(a) upper and lower body portions freely slidable within said tubing string and having longitudinal bores therethrough sized to freely pass the sucker rod, each portion having a longitudinal slot in its side wall extending radially into the bore and longitudinally the full length of the body portion, and the adjacent ends of the portions having matching transverse surfaces which they can mutually abut;

(b) actuator means fixed in one body portion, circumferentially displaced from the associated slot of the one body portion, and extending longitudinally through the slot in the other body portion and terminating therebeyond and including means to prevent withdrawal of the actuator means from the last mentioned slot; said slots being out of mutual alignment and Y (c) detent means carried by said body portions and operative to releasably hold the body portions together when the latter are abutted.

7. In a scraper as set forth in claim 6, said actuator means comprising a rod having one end fixed in the lower body portion and the other end terminating above the upper body portion and partly surrounding the sucker rod and comprising said withdrawal preventing means.

8. In a scraper as set forth in claim 6, the slot in the lower -body portion being skewed at an acute angle with respect to the axis of the bore therethrough.

9. In a scraper as set forth in claim 6, said actuator means comprising a rod having one end fixed in the lower body portion and extending through the slot in the upper body portion, and said detent means comprising a resilient plug fixed to the lower portion at the rod and resiliently distortable to -frictionally grip said slot when entered thereinto, the slot in the upper portion having recesses therein and the plug having protrusions shaped t yieldably lodge in the recesses. Y

10. In a scraper as set forth in claim 6, said body portions having annular grooves in their outer surfaces, and having radially disposed fins in said grooves, the fins conforming with the peripheral shapes of the body portions, but extending therebeyond in radial directions.

11. In oil well equipment, a parafn scraper assembly for migrating up and down on a sucker rod within a surrounding tubing string, comprising:

(a) upper and lower body portions within the tubing string and substantially surrounding the sucker rod and sized to be freely slidable longitudinally of both, the body portions being substantially cylindrical and having longitudinal passageways in their sides for conducting well uids from one end of the scraper to the other, and having radially disposed adjacent end surfaces which block the passageways when abutted;

o (b) actuator means fixed to one body portion and extending through a passageway in the other portion and therebyond, and disposed to maintain the passage-` ways in the two portions out of mutual alignment;

' (c) means for limiting the longitudinal separation of the body portions; and

(d) means for yieldably maintaining the body portions in abutting position when the end surfaces are mated.

12. In a scraper as set forth in claim 11, said actuator means comprising a rod having one end iixed in the lower body portion and the other end terminating above the upper body portion and having an enlargement at said other end to prevent withdrawal of the rod from the passageway.

13. In a scraper as set forth in claim 11, a passageway in one of the body portions being skewed at an acute angle with respect to the axis of the Ibore therethrough.

14. In a scraper as set forth in claim 11, said actuator means comprising a rod having one end fixed in the lower body portion and extending through a passageway in the upper body portion, and said detent means comprising a resilient dart-shaped plug fixed to the lower portion at the rod and resiliently distortable to frictionally grip said passageway when entered thereinto.

Y 15. In a scraper as set forth in claim 11, said detent means comprising vmagnet means embedded in the body Iportions adjacent said transverse surfaces mutually attract-v ing the portions when mated.

References lCited UNITED STATES PATENTS CHARLES E. OCONNELL, Primary Examiner.

JAMES A. LE-PPINK, Examiner.

Claims (1)

1. IN OIL WELL EQUIPMENT, A PARAFFIN SCRAPER ASSEMBLY FOR MIGRATING UP AND DOWN ON A SUCKER ROD HAVING SPACED ABUTMENTS THEREON AND LOCATED WITHIN A SURROUNDING TUBING STRING, COMPRISING: (A) UPPER AND LOWER BODY PORTIONS FREELY SLIDABLE WITHIN SAID TUBING STRING AND HAVING LONGITUDINAL BORES THERETHROUGH SIZED TO FREELY PASS THE SUCKER ROD, SAID PORTIONS HAVING LONGITUDINAL SLOTS IN THEIR SIDE WALLS EXTENDING THE FULL LENGTH OF THE BODY PORTION, AND THE ADJACENT ENDS OF THE PORTIONS HAVING MATCHING TRANSVERSE SURFACES AT WHICH THEY CAN MUTUALLY MATE; (B) MEANS FOR MAINTAINING THE SLOTS IN THE BODY PORTIONS OUT OF MUTUAL ALIGNMENT; (C) ACTUATOR MEANS ATTACHED TO ONE PORTION AND EXTENDING BEYOND THE OTHER PORTION AND OPERATIVE TO SEPARATE THE BODY PORTIONS WHEN THE ACTUATOR MEANS STRIKES AN ABUTMENT; AND

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