US3141505A - Methods and apparatus for scraping paraffin - Google Patents

Description

y 21, 1964 J. c. TRIPPLEHQRN METHODS AND APPARATUS FOR SCRAPING PARAFFIN Filed April 10, 1961 INVENTOR JAMES C. TRIPPLEHORN ATTORNEYS United States Patent 3,141,505 l'flTHGDS AND APPARATUS FOR SCRAPING PARAFFIN James C. Tripplehorn, 1M3 Mary Ellen St., Pampa, Tex. Filed Apr. 10, 1961, Ser. No. 102,059 8 Claims, (Cl. 16643) This invention relates to novel methods and combinations of several types of paraffin scrapers for use in connection with the pumping of wells, wherein one of said types grips the sucker rod and remains fixed with respect thereto while scraping paraffin from the inside wall of the pump tubing as the rod is reciprocated, and the other type grips the inside wall of the tubing and remains fixed with respect thereto and scrapes paraffin from the outer surface of the sucker rod reciprocating therethrough. This invention also relates to a novel method of simultaneously cleaning both the tubing and the sucker rod, and also to a novel method of installing and positioning the tWo types of scrapers in alternating sequence around the sucker rod and inside the tubing so that the scrapers of each type are mutually spaced apart by the length of the pumping stroke.

The principal object of this invention is to provide a method and means for positively and efiiciently scraping parafiin both from the tubing wall and from the sucker rod surface on each pump stroke.

It is a more specific object of this invention to provide a novel method of installing and positioning the scrapers wherein rod-gripping scrapers and tubing-gripping scrapers are alternatively disposed along the sucker rod, the rodgripping scrapers being fixed to the rod and spaced apart by distances substantially equaling the pumping stroke of the sucker rod, and each tubing-gripping scraper being loosely disposed around the sucker rod between two adjacent rod-gripping scrapers, and wherein said rod with the scrapers alternatively disposed thereon is then run into the tubing, preferably entering through a flared nipple, and, finally, the rod is reciprocated in the tubing through said pumping stroke in order to space the tubing-gripping scrapers apart also substantially by the length of the pumping stroke. When the scrapers and the rod are thus installed in the tubing, further reciprocation of the rod causes positive cleaning of substantially the full length both of the inside wall of the tubing and also of the outer surface of the sucker rod. Most prior-art paraffin scraping methods and apparatus have been directed toward attacking only the accumulation of parafiin on the tubing wall, and little or no effort has been made to remove accumulated paraflin from the sucker rod.

It is a further object of this invention to provide a scraper combination as set forth above wherein the sucker rod and all of the scrapers can be relatively easily removed from the pump tubing by merely exerting sufficient pull on the sucker rod to overcome the frictional engagements with the tubing of the tubing-gripping scrapers, this feature permitting disassembly of the pumping string and convenient recovery of the individual scrapers therefrom.

The above method of installation and removal of the sucker rod and all of the scrapers is based on the fact that the frictional grip of the individual tubing-gripping scrapers need not be extremely tight, provided the paraffin deposits are scraped and pumped out with such efficiency that they never build up in large masses. Such build-up is highly undesirable not only because the presence of the parafiin reduces the annular area of the oil passage between the tubing string and the sucker rod and thus reduces the flow of oil to the surface, but also because of the fact that the build-up of paraffin prevents free motion of the sucker rod in the tubing and results in the eventual bogging-down of all sucker rod motion in the tubing since large accumulated loads of paraffin around the sucker rod periodically drop on the rod and dislodge the fixed scrapers, sometimes bunching them together in a mass of hard-packed parafiin which securely anchors the rod to the tubing walls and makes it necessary to pull both the rod and the tubing together at considerable expense.

On the other hand, parafiin deposits are scraped away very easily if they are not permitted to build up excessive masses in the first place, and it is an object of this invention to prevent such build-ups both on the tubing wall and also on the sucker rods.

Another object of this invention is to provide a combination of parafiin scrapers in which the individual units may be installed anywhere along the length of a sucker rod between the tool joint ends thereof without necessitating any altering of the standard sucker rod, or damaging the same, as for instance by welding.

Yet another object of the invention is to provide a transverse abutment surface on the end of at least one paraffin scraper in each adjacent pair, said abutment surfaces serving to permit mutual contact of the scrapers without intertwining or tangling thereof so as to confine each of the scrapers to the particular length of the pumping string to which it is assigned.

The illustration of the present invention includes rodgripping scrapers of the type disclosed in my Patent 2,928,- 473, and these rod-gripping scrapers are alternated with tubing-gripping scrapers which in one embodiment are constructed similarly to those disclosed in my Patent 2,595,025, with the exception that the spiral springs are increased in diameter so that they grip the tubing wall but permit free sliding of the sucker rod through their centers.

In another embodiment illustrated in the present disclosure, tubing-gripping scrapers of a different and novel type are employed, these scrapers being made of nylon or some other plastic material, examples of which materials are set forth in the above mentioned Patent 2,928,- 473. However, these novel tubing-gripping scrapers function similarly to the spiral wire scrapers to the extent that they expand outwardly and grip the tubing, and have openings through their centers large enough to permit free reciprocation of the sucker rod therethrough.

It is another object of the present invention to provide a novel tubing-gripping scraper made of a type of plastic as set forth above for which paralfin has very little affinity so that the very paraffin which is sought to be scraped away by these improved scrapers does not tend to build up on them.

It is another important object of the present invention to provide in the novel combination of two different types of parafiin scrapers, rod-gripping scrapers having outer diameters less than the inside diameter of the tubing and adapted to frictionally engage and remain fixed on the sucker rod, and to provide resilient tubing-gripping scrapers having outer diameters which in relaxed condition are larger than the inside diameter of the tubing, these latter scrapers being radially compressible so that they can be contracted for entry inside the tubing, and so that when inside the tubing they always expand into tight engagement with the inner surface of the tubing to frictionally retain the scrapers in place therein.

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

FIG. 1 is an elevation view, partly in cross section, of a pump-tubing and sucker rod string equipped with alternate scrapers of different types according to the present invention;

FIG. 2 is a view similar to FIG. 1, but on a larger scale 3 and illustrating the engagements of the respective rodgripping scrapers and tubing gripping scrapers;

FIG. 3 is a sectional view through a length of pumptubing illustrating a novel tubing-gripping paraffin scraper according to the present invention;

FIG. 4 is a section taken along line 44 of FIG. 3; and

FIG. 5 is an enlarged cross-section view taken along line 5-5 of FIG. 2.

Referring now to the drawings, FIGS. 1 and 2 illustrate a length of sucker rod R extending through a length of tubing T in which it reciprocates. Around the rod R and within the tubing T there are two series of parafiin scrapers alternately disposed with respect to each other and respectively frictionally gripping the tubing and the sucker rod according to the teaching of the present invention. In the particular embodiment illustrated in F563. 1 and 2 the paraffin scrapers which grip and are fixed to the sucker rod R, each comprise a body 1 having upper and lower similar end bosses 2. Each body 1 comprises a spiral blade having sides which are located between an arcuate inner peripheral surface which conforms to the shape of the sucker rod and an outer peripheral surface 3 which serves to scrape against the tubing wall as the sucker rod lashes back and forth while being reciprocated inside of the tubing string. As stated above, this type of scraper is fully described and claimed in my Patent 2,928,- 473, and therefore need not be described in detail herein. However, it is to be noted that each of the bosses has a bore therethrough which is normally slightly smaller than the diameter of the sucker rod, and passage of the sucker rod into the bore is through a slot 2a in each boss 2 when the scrapers are applied to the sucker rod. These scrapers are made of a spring-like plastic material such as nylon, and it is the spring-like quality of the plastic material that causes each of the bosses 2 to tightly grip the sucker rod and be frictionally retained thereon in the longitudinal position in which the scraper was originally attached.

This is not the only type of scraper which can be used in carrying out the method of the present invention. The principal requirement of the rod-gripping scrapers is merely that they tightly cling to the sucker rod and remain fixed in their assigned longitudinal positions spaced there on substantially by the length of stroke of the sucker rod, and also that at least one type of the scrapers have abutment surfaces such as the surfaces 222 or b at their ends which will not tangle with the ends of the adjacent scrapers of the other type. FIGS. 1 and 2 show tubinggripping scrapers formed by spring wire, of the general type illustrated in my Patent 2,595,025, or even of spiral plastic scrapers for instance of the type illustrated in my Patent 2,969,115. These helical scrapers 5 are formed so that they have central convolutions 5a which expand tightly against the inner wall of the tubing T and frictionally grip the same. The end convolutions 5b are of similar diameter and extend inwardly toward the sucker rod R so as to scrape the surface of the sucker rod as it reciprocates through the scrapers 5 which remain substantially stationary on the inner wall of the tubing T. The end convolutions 5b are formed so as to leave a large enough bore through the scraper itself that the sucker rod may pass freely therethrough, the scraping action being accomplished completely as the sucker rod lashes back and forth transversely of the tubing as it reciprocates. It is not necessary that every portion of the outer surface of the rod be scraped during each stroke thereof, but only that on an average basis every portion of the surface be frequently scraped on substantially its entire surface. This same fact applies also to the scraping of the tubing by the rod-gripping scrapers 1.

Referring now to FIGS. 3 and 4, the same tubing T with the sucker rod R extending therethrough is illustrated in these figures, but in addition a different type of tubinggripping scraper is illustrated. This tubing-gripping scraper includes a substantially cylindrical body it? having internal ribs 12 which extend into the bore ltla of the cylindrical body it). The innermost edges of the ribs 12 are spaced far enough apart so that they do not grip the sucker rod but face toward the sucker rod and scrape thereagainst as the latter is reciprocated. The cylindrical body It is also provided with external ribs 14 the outer surfaces of which lie on a cylindrical surfac the normal diameter of which is greater than the inside diameter of the tubing T. The circular body 1% is discontinuous between two of the pairs of the internal and external ribs 12 and M in the vicinity of the end of the lead line from the reference character l6 and this discontinuity in the cylindrical body 1% permits it to contract in order to enter the tubing T and then expand tightly against the inner wall of the tubing T in order to maintain the scraper in place with respect thereto. The ribs 12 and i are all helically or diagonally disposed with respect to the axis of the annular body it) and the body length is such that the upper end 14a of one set of ribs 124.4, on one side of the discontinuity, overlaps the lower end 14b of the set of ribs 12-14, located on the opposite side of the discontinuity in the cylindrical body 19. Incidentally, this discontinuity at 16 comprises a slot through the cylindrical body it) which permits the scraper to be installed on the sucker rod before the latter is lowered into the Well. The diagonal disposition of the ribs on the body it provides better scraping action because they cover a larger sector of the red when it contacts them, and the ribs also serve to take any wear which occurs between the scraper and either the rod or the tubing during relative motions thercbetween caused by installation and/ or stroking. it is not desirable that the body 15 take any of this wear in View of the fact that the body it) between the sets of ribs is made relatively thin so that it can flex and thereby permit radial compression and expansion of the scraper.

As stated above, all of the tubing-gripping scrapers are mutually positioned within the tubing by the stroking of the sucker rod and the abutment of the tubinggripping scrapers with the rod-gripping scrapers until the former have been positioned midway of the pumping stroke of the latter. It is, therefore, also apparent that even if occasional clots of solid material should bump a tubing-gripping scraper and shift its position longitudinally within the tubing, the next complete pumping stroke will reposition it in its former and correct location, namely midway of the stroke of the portion of the sucker rod lying between the two adjacent rod-gripping scrapers.

I do not limit my invention 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. The method of cleaning parafiln both from the surface of a pump rod and from the inner wall of a pump tubing, including the steps of reciprocating the former in the latter through a stroke of predetermined length while simultaneously both scraping paralfin from the pump rod at a plurality of substantially fixed locations on the tubing which are mutually spaced apart by the length of the stroke, and also scraping paraffin from the tubing wall at a plurality of locations substantially fixed with respect to the rod and disposed in alternating sequence with said first-mentioned locations and also mutually spaced apart by said length of strokes.

2. The method of cleaning paraffin using paraffin scrapers both from the surface of a pump rod and from the inner wall of a pump tubing when the former is reciprocated in the latter through a stroke of predetermined length, including the steps of fixing a first series of scrapers to the pump rod mutually spaced apart by the length of the stroke; locating a second series of scrapers in positions substantially fixed with respect to the tubing wall and in alternating sequence with the scrapers of the first series and also mutually spaced apart by said length of stroke; and then reciprocating the rod through said length with respect to said tubing.

3. The method of removably installing a series of resiliently expansible tubing-gripping scrapers in wellpump tubing in alternate succession with a series of sucker rod-gripping scrapers, the scrapers in each series being mutually spaced apart by the length of a predetermined pumping stroke, including the steps of clamping the rod-gripping scrapers on the sucker rod in fixed relation therewith and spaced apart substantially by said stroke; applying a tubing-gripping scraper in loose sliding engagement on the rod between each two clamped scrapers; introducing the sucker rod and the scrapers into the tubing; and reciprocating the sucker rod therein through the length of said stroke to locate said tubinggripping scrapers in the tubing in stationary positions between the rod-gripping scrapers, the tubing-gripping scrapers being thereby also mutually spaced apart substantially by the length of said stroke.

4. For use in a reciprocating pump string including a sucker rod within a pump tubing, the combination of alternately disposed rod-gripping scrapers and tubinggripping scrapers, said rod-gripping scrapers having means for tightly gripping the sucker rod and being clamped to and spaced apart along the rod substantially by the length of stroke of the pump and fitting freely inside the tubing; and said tubing-gripping scrapers each having resilient means for frictionally gripping the inside surface of the tubing and having a central opening freely passing the sucker rod.

5. In a combination as set forth in claim 4, at least one scraper of each adjacent pair of scrapers having transverse end surface means for abutting the end of the adjacent scraper without tangling therewith, whereby the scrapers clamped on the rod, when the latter is reciprocated through said stroke, force the tubing-gripping scrapers to positions wherein the latter are mutually spaced apart substantially by the length of said stroke.

6. In a combination as set forth in claim 4, said tubinggripping scrapers having an outside dimension, as measured transversely of the scraper in at least one direction, larger than the inside diameter of the tubing and being resiliently yieldable in that direction to permit entry of the scraper into the tubing.

7. A tubing-gripping scraper for cleaning a sucker rod within a string of pump tubing, comprising an annular substantially cylindrical resilient body having circumferentially spaced pairs of internal and external ribs disposed therearound, the ribs in each pair being mutually radially aligned and inclined at an angle to the axis of the body, and the body having a slot through its side located between annularly adjacent pairs of ribs and inclined at the same angle with respect to said axis as said ribs, the width of the slot substantially equaling the diameter of the sucker rod, the diameter of a cylinder touching the outermost surfaces of the external ribs being greater than the inner diameter of the tubing and the diameter of another cylinder touching the innermost edges of the internal ribs being not less than the diameter of the sucker rod.

8. In a scraper as set forth in claim 7, the body having an axial length great enough that the slot at one end of the body is circumferentially displaced from the slot at the other end of the body by at least the width of the slot.

References Cited in the file of this patent UNITED STATES PATENTS 1,758,995 Armstrong et al. May 20, 1930 2,200,758 Thaheld May 14, 1940 2,928,472 Tripplehorn Mar. 15, 1960

Claims (3)

1. THE METHOD OF CLEANING PARAFFIN BOTH FROM THE SURFACE OF A PUMP ROD AND FROM THE INNER WALL OF A PUMP TUBING, INCLUDING THE STEPS OF RECIPROCATING THE FORMER IN THE LATTER THROUGH A STROKE OF PREDETERMINED LENGTH WHILE SIMULTANEOUSLY BOTH SCRAPING PARAFFIN FROM THE PUMP ROD AT A PLURALITY OF SUBSTANTIALLY FIXED LOCATIONS ON THE TUBING WHICH ARE MUTUALLY SPACED APART BY THE LENGTH OF THE STROKE, AND ALSO SCRAPING PARAFFIN FROM THE TUBING WALL AT A PLURALITY OF LOCATIONS SUBSTANTIALLY FIXED WITH RESPECT TO THE ROD AND DISPOSED IN ALTERNATING SEQUENCE WITH SAID FIRST-MENTIONED LOCATIONS AND ALSO MUTUALLY SPACED APART BY SAID LENGTH OF STROKES.

4. FOR USE IN A RECIPROCATING PUMP STRING INCLUDING A SUCKER ROD WITHIN A PUMP TUBING, THE COMBINATION OF ALTERNATELY DISPOSED ROD-GRIPPING SCRAPERS AND TUBINGGRIPPING SCRAPERS, SAID ROD-GRIPPING SCRAPERS HAVING MEANS FOR TIGHTLY GRIPPING THE SUCKER ROD AND BEING CLAMPED TO AND SPACED APART ALONG THE ROD SUBSTANTIALLY BY THE LENGTH OF STROKE OF THE PUMP AND FITTING FREELY INSIDE THE TUBING; AND SAID TUBING-GRIPPING SCRAPERS EACH HAVING RESILIENT MEANS FOR FRICTIONALLY GRIPPING THE INSIDE SURFACE OF THE TUBING AND HAVING A CENTRAL OPENING FREELY PASSING THE SUCKER ROD.

7. A TUBING-GRIPPING SCRAPER FOR CLEANING A SUCKER ROD WITHIN A STRING OF PUMP TUBING, COMPRISING AN ANNULAR SUBSTANTIALLY CYLINDRICAL RESILIENT BODY HAVING CIRCUMFERENTIALLY SPACED PAIRS OF INTERNAL AND EXTERNAL RIBS DISPOSED THEREAROUND, THE RIBS IN EACH PAIR BEING MUTUALLY RADIALLY ALIGNED AND INCLINED AT AN ANGLE TO THE AXIS OF THE BODY, AND THE BODY HAVING A SLOT THROUGH ITS SIDE LOCATED BETWEEN ANNULARLY ADJACENT PAIRS OF RIBS AND INCLINED AT THE SAME ANGLE WITH RESPECT TO SAID AXIS AS SAID RIBS, THE WIDTH OF THE SLOT SUBSTANTIALLY EQUALING THE DIAMETER OF THE SUCKER ROD, THE DIAMETER OF A CYLINDER TOUCHING THE OUTERMOST SURFACES OF THE EXTERNAL RIBS BEING GREATER THAN THE INNER DIAMETER OF THE TUBING AND THE DIAMETER OF ANOTHER CYLINDER TOUCHING THE INNERMOST EDGES OF THE INTERNAL RIBS BEING NOT LESS THAN THE DIAMETER OF THE SUCKER ROD.

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