US2733768A

US2733768A - Spiral paraffin scrapers

Info

Publication number: US2733768A
Authority: US
Publication date: 1956-02-07
Anticipated expiration: 1973-02-07

Description

Feb 31956 D. R. TRIPPLEHORN SPIRAL PARAFFIN SCRAPERS Filed June 1, 1953 DA v/DRfIk/PPL EHO/EN INVENTOR ATTORNEYS United 1 atent O 'ce SP PFIN scans David R. Tripplehorn, Fort Worth, Tex., assignor to James C. Tripplehorn, Pampa, Tex.

Application June 1, 1953, Serial No. 358,849

5 Claims. (Cl. 166-176) My invention is an improved spiral parafiin scraper of the type which grips a sucker rod and is maintained in position thereon by friction.

The principal object of my invention is to provide a spring steel spiral parafiin scraper which may be quickly and easily installed on or removed from a sucker rod by any member of a drilling crew at the well site. According to a recent survey made of the oil industry it appears that the most common type of parafiin scraper is the type shown in Patent No. 2,453,199, this scraper being secured in place by welding. Because of the fact that the welding of the ends of the scraper to a sucker rod destroys the temper of the rod in the vicinity of the weld,

it is not practical to attempt to weld a scraper to a rod at the well site, and it is therefore necessary and common practice to ship the sucker rods to an installation factory where metal bands are shrunk around the rods, the scrapers being subsequently welded to these bands instead of to the rods. I have therefore provided the paralfin scraper which is the subject of the present patent application and which is entirely satisfactory to both the well operators and to the manufacturers of the sucker rods. My invention eliminates the necessity of shipping the rods to an installation factory for installation of scrapers, and at the same time provides a paraffin scraper which, according to actual tests, grips the rods so tightly that a' force, well in excess of those encountered in normal well operations, is required to cause the scraper to slip on the rod. The elimination of the necessity of shipping sucker rods to installation factories to have scrapers welded thereon effects a considerable saving in cost and time.

Another very important object of my invention is to provide a paraffin scraper which will not nick or bite into the sucker rod in the manner intended and set forth in some prior-art disclosures, showing a spiral paraffin scraper having each end turned in so as to bite into the rod. Such a bite into the rod by the end of the scraper, of course, increases the grip of the scraper on the rod, but the nicking of the rod causes frequent breakage thereof by creating a weak spot therein. Consequently this type of scraper is definitely not recommended by manufacturers of the drill rods, and, in fact, has apparently not been marketed at all.

Another important advantage of my paraflin scraper is that, since the latter is installed at the well site, the spacing between adjacent scrapers may be altered to suit the length of stroke of the particular pump which is used, thereby obviating the disadvantage of the type of paraflin scraper which is welded to the sucker rod which can not be longitudinally repositioned at the site of the drilling operation, and can not be transferred to a new rod from a damaged one.

Another important object of my invention is to provide a spiral parafiin scraper which may be economically manufactured of heat treated spring steel, the present practice being to use No. 1095 spring steel having a Rockwell hardness of 43 when heat treated.

2,733,768 Patented Feb. 7, 1956 The principal feature of novelty of my invention resides in the ends of the scraper which, like the body of the scraper, are substantially rectangular in cross-section and which are perpendicularly disposed with respect to the surface of the rod. It is an important object of my invention to provide a paraflin scraper having ends which are each tapered both inwardly and outwardly in a direction radially of the rod as shown in the accompanying drawing. Each end of the scraper is tapered inwardly so as to prevent the end from engaging on tool joints in the well tubing; and in addition, the inside edge of each end of the scraper is tapered outwardly from the surface of the sucker rod so as to insure that the frictional gripping of the helix of the scraper on the sucker rod will occur and will be uniform along the entire inner periphcry of the scraper intermediate its tapered ends. Otherwise the inner periphery of the helix may be bowed outwardly from the rod somewhere along the line of contact caused by distortion of the helical shape of the scraper when one or both ends bite into the rod. The tapering of the inner periphery at the ends assures that there will be no inwardly projecting discontinuities.

Another advantage of tapering the end of the scraper outwardly from the surface of the sucker rod is to pro- ,vide a small clearance at each end between the inner periphery of the scraper and the surface of the sucker rod so that a screw-driver or other tool may be inserted therebetween for the purpose of removing the scraper from the rod.

Another very important object of my invention is to i provide a scraper having ends which are not bent very far from the original shape of the bar stock prior to shaping of the helical scraper. It has been found that, during the manufacture of spiral scrapers wherein each end of the scraper is bent through a considerable angle so as to provide hooked ends such as are shown in some prior-art disclosures, when this type of scraper was tested in actual operation within oil wells, the ends frequently break off of the scraper and not only reduce the gripping power of the scraper but also tendto wedge between moving parts within the well and cause damage to the tubing and sucker rod or to the remaining portion of the scraper. Further tests were run in order to determine the cause of such breakage and it was discovered that the breakage was due to the complex bending of the ends of the annealed bar stock during shaping of the scraper and prior to final heat treating thereof. It the ends of the scraper are bent very sharply or in several different directions, the grain structureof the annealed spring steel is overstressed in such a way as to cause hidden damage thereto. My invention eliminates most of this complex bending of the ends of the scraper so that the device set forth in the present application has substantially as strong a grain structure at its ends as it has elsewhere along its length.

Another important object of my invention is to provide a helical scraper having its end portions lying in a continuation of the helical form of the body of the scraper so that there are no complex bends which increase turbulence in the flow of the oil therepas t, such turbulence greatly restricting the flow of fluid upwardly through the tubing. Parafiin tends to build up on complex bends to the extent that free flow of well liquid is retarded.

Another advantage of my scraper is that since the ends thereof conform with the helical shape of the body of the scraper, it is possible to nest more of these scrapers together for the purpose of shipment than is possible with scrapers of the type wherein the end structure of the scraper does not conform withthe helical shape of the body and thereby prevents nesting of a large number of scrapers together for shipment.

Ether objeets'and- 'advantages of my invention will become. apparentduring the. following .discussion. of the drawing wherein:

Figure 1 is a longitudinal view of a pump tubing, broken away toshownthe sucker rodwithinsaid tubing having-one of my spiral paraffin scrapersfixed thereto.

:Fig. 2 is an enlarged-section viewalong line 2-2' of Fig. 1.

. --Fig. 3 is -an enlarged view of one end of my spiral paraffn scrapersecured to the sucker rod.

Fig. 4 is asection view along line44 of Fig. 3.

Fig.. 5 is a view of one end of the rectangular spring steel stock from which my parafiin scrapers are made, this view showingthe-end of the rod tapered at an angle of approximately for the purpose hereinafter discussed.

.Refer-ring-nowthe drawing, Figs. land 2 showa'pump tubing T having -a sucker rod R axially disposed therein, the tubing and the rod-beingstandard equipment and forming no part .of the present invention. A spiral parafiin'scraper 1, according to the-present invention, is shown frictionally gripping therod R, the scraper having identical upper and lower'ends. Each of these ends is tapered inwardly towardthe rod R as at 2 so as to prevent snagging of the scraper on'the 'joints of the tubing T, and each end of the inner-periphery of the spiral scraper is tapered outwardly fromthe-rod R as at 3, for thepurpose hereinafter stated; Attention is'called to the fact that each end of "the paraflin-scraper conforms with the general'helical form of the body of the scraper and is a continuation thereof so that the paraffnscraper endsare perpendicular to the-adjacent surface of the sucker rod and do not tend to turn over or lie flat thereagainst. The "fact that thescraper ends conform to the general helical shape of the body of the scraper-permits the spiral flow of well fluids to washall exposed surfaces of the scraper and the rod to prevent the building up ofparaflin deposits.

The p'araflin scraper itse'lf is manufactured-from substantially rectangular 1095 spring steel stock, which stock has been cut at each end in the manner shown in "Fig. 5 so as to provide at the terminal portions'of the stock an'approximate 10 angle before thestock is formed into'the helix. After the spring steel stock In is formed into the helical shape, the outer surface of the stock at the ends thereof in the vicinity of 2a, Fig. 5, is bent slightly inwardly so that the tapered surface 3a partially approaches the inner periphery of the helix. In this manner both the inner andtheouter edges of the ter- 'minal portions ofthe'scraperare shaped with a minimum bending" of the annealed spring steel.

During the forming of the spring steel flatstock 1a into thehelicalscraper 1, the inner periphery 4 of the helix is formed'to'provide a uniform diameter somewhat less than the outer'diameter of-the sucker rod which the scraper is intended to grip, and this inner diameter is "uniform along the full length ofthe'scraperbetween the "tapered ends3 so that the grip of the scraper on the-sucker -rod will be uniform along substantially its full-length except at the terminal ends which do not contact therod.

In operation disturbed; 'F- SeVere. stresses :occur tending to :stretch siwkerarods whenxaipiunp.fails tor-sandsup. 'When a rod is stretched by a pulling rig tryingtofree a-stuckplunger,

tapered respectively towardeach other, said terminaltpor- 'tions forming continuations of the spiral shape ofzsaid d the diameter of the rod is decreased enough to permit a scraperto slide thereon and approachan adjacent scraper.

My scraper is quickly and easily installed on a sucker rod without necessitating special tools, such installation being carried out merely by hand with the assistance of a screw-driver or tire iron to maintain one end of the scraper in place on the rod while the body of the scraper is manually wound therearound. When one end and the body of the scraper are secured in place, the other end of the scraper may be positioned by placing a screw-driver under that end and against the rod and snapping .theend in place on the rod. Removal of the scraper from the rod, of course, is easily accomplished by merely sliding a screw-driver between the sucker rod and the inner periphery 3 of one end of the'scraper and prying that end of the scraper off of the rod, the disengagement of the body of the scraper being easily accomplished by manual unwinding thereof.

Tests of actual production models of this scrapershow thatit grips the smoker rod so tightly that a force of 2350 pounds is required to cause slippage thereofon the rod, and testsmade during actual operation in wells show that even after a rod has been stressed orstretched so that its diameter is slightly reduced, my paraifn scrapers do not slip-on the rod under normal operating conditions.

I do notlimit my invention to the exact form shown in the drawing, for obviously changes may be madetherein within thescope of the claims.

ing-opposed narrow edges and being wound in the form of a helix, said blade frictionally engaging said-rod along'one narrowedge and standing normal to said-rod along the full length of the scraper, the said narrow edges being tapered at the ends of said scraper to partially. approach each other.

2. A removable spiral parafiin scraper adapted to frictionallyengage a sucker rod'within the tubing ofa well,

.said .scrapercomprising a spiraled blade of spring material having'an inner periphery defining a bore through the scraper, the bore being normally of smaller diam- 'eter than the diameter of the sucker rod whereby said 'inner periphery will tightly grip said rod when the scraper is engaged thereon, said blade being of helical shape andbeing disposed normal to said rod along the full length of the scraper, and the-inner peripheryat the ends of the scraper being tapered outwardly away from the rod whereby the ends of the scraper will be prevented from biting into said rod.

. In-a scraper as set forth in-claim 2, said blade having an outer periphery, and the outer peripherywbeing tapered inwardly toward .said rod at the ends of the scraper to prevent snagging of the scraper insaid ,tubing.

4. A'spiral'parafiin scraper adapted to engage a sucker rod within the tubing of a well through which :tubing fluid is-fiowing, said scraper comprising-a spiraled blade of spring material having narrow surfaces forming respectively the outer-and inner peripheries of thescraper said inner periphery frictionally gripping saidsucker rod, and said blade having broad surfaces disposed substantially-normal to said rod along the full length of. said scraper, and each-end of said-blade having aterminal portion whereat said inner -.and outer peripheries rare body to therebypresenta minimum impedance to:.the flow of said fluid.

5. -A spiralparaflin scraper adapted to engage azsucker rod within the tubing of a well, saidscraper=comprising a spiraled blade of spring material substantially rectan- 'guiarin cross section, said blade having narrow surfaces forming respectively they outer ,andinner peripheries of the scraper said inner periphery frictionally gripping said sucker rod, and said blade having broad surfaces disposed substantially normal to said rod along the full length of said scraper, and each end of said blade having a terminal portion whereat said inner and outer peripheries are tapered respectively toward each other 5 thereby tapering the terminal portion of the outer periphery inwardly toward the rod to prevent snagging of the ends against said tubing and tapering the terminal portion of the inner periphery outwardly away from the rod whereby the grip of the scraper on the rod will occur 10 intermediate said terminal portions.

References Cited in the file of this patent UNITED STATES PATENTS

Claims

1. A REMOVABLE SPIRAL PARAFFIN SCRAPER ADAPTED TO FRICTIONALLY ENGAGE A SUCKER ROD WITHIN THE TUBING OF A WELL, SAID SCRAPER COMPRISING A BLADE OF SPRING MATERIAL HAVING OPPOSED NARROW EDGES AND BEING WOUND IN THE FORM OF A HELIX, SAID BLADE FRICTIONALLY ENGAGING SAID ROD ALONG ONE NARROW EDGE AND STANDING NORMAL TO SAID ROD ALONG THE FULLL LENGTH OF THE SCRAPER, THE SAID NARROW