US2678696A

US2678696A - Paraffin scrapper for wells

Info

Publication number: US2678696A
Application number: US222708A
Authority: US
Inventors: Wilfred S Crake
Original assignee: Shell Development Co
Current assignee: Shell Development Co
Priority date: 1951-04-24
Filing date: 1951-04-24
Publication date: 1954-05-18
Anticipated expiration: 1971-05-18

Description

y 3, 1954 w. s. CRAKE PARAFFIN SCRAPER FOR WEELS 3 Sheets-Sheet 1 Filed April 24, 1951 lnvenTOr: WAWred 5.640%6 W. S. CRAKE PARAFFIN SCRAPER FOR WEELS May 18, 1954 5 Sheets-Sheet 2 Filed April 24 1951 Inve nTor: wlwmd 5. came 55'- y 8, 1954 w. s. CRAKE 2,678,696

PARAFFIN SCRAPER FOR WEELS Filed April 24 1951 3 Sheets-Sheet 3 PIC-1.9

Invenfor: Wmred SCroke 6&5- QPQWW His Afiorneg Patented May 18 1954 UNITED STAT were T QFFICE PARAFFIN SCRAPPER FOR WELLS Application April 24, 1951, Serial No. 222,708

8 Claims.

This invention relates to the removal of deposits from the internal walls of oil well pipe and pertains more particularly to the removal of parafiin or other deposits from the interior of an oil production tubing string in a well when said well is being produced.

It is well recognized that in some oil-producing areas the oil may contain a substantial amount of a waxy constituent, such as paraflin, which is in the liquid state when at the bottomhole well temperature and pressure. As the oil is pumped or allowed to flow up the production tubing to the top of the well, the temperature of the oil gradually decreases until a point is reached at which the paraffin crystallizes out and accumulates on the internal walls of the tubing. In time, the parafiin accumulation continues to build up until the volume of production from the well is materially reduced or stopped entirely. The operator of the well is then faced with the problem of removing the paraffin, the removal thereof being generally both expensive and time-consum- It is therefore an object of this invention to provide an apparatus for preventing the accumulation of parafiin deposits on, or for removing accumulated paraflin deposits from, the internal wall or" a production tubing in an oil well.

Another object of the present invention is to provide a device for removing parafiin deposits from the interior of a reciprocating production tubing which is employed to actuate a well pump, said paraffin remova1 taking place while the well is being produced and without the necessity of shutting down the well pump.

A further object of this invention is to provide an apparatus for continuously removing paraflin deposits from the interior of a production tubing in a flowing oil well without interrupting the production of the well.

Another object of the present invention is to provide a parafl'in-removing device adapted to pass through an oil well production tubing, said device being arranged in said tubing in a manner to permit the reciprocation and/or rotation of the device with respect to the tubing.

These and other objects of this invention will be understood from the following description of the invention as shown in the accompanying drawing, wherein:

Figure l is a view, partly in enlarged detailed cross section, of the present paraffin-removing apparatus positioned in and above a well, said well being produced by reciprocation of the production tubing secured to a pump.

Figure 2 is an enlarged side elevation view of a portion of the equipment shown in Figure 1 for reciprocating and rotating the production tubing.

Figures 3, 5 and 8 are views, partly in enlarged cross section, of other embodiments of the present parafiin-removing apparatus positioned in and above a free-flowing well.

Figure 4 is a cross-sectional view of the stuffing box 53 shown in Figure 3.

Figure 6 is a cross-sectional View or the hanger head as shown in Figure 5.

Figure '7 is a cross-sectional view taken along the line 'i'-l of Figure 6.

Figure 9 is a cross-sectional view of the tubing hanger 9t shown in Figure 8.

Referring to Figure l. of the drawing, one embodiment of the present invention is illustrated as utilized to remove paraifin from the interior of a production tubing H extending down into a well casing 52 to a plunger-type well pump (not shown) which is reciprocated by repeated upward and downward movement of the tubing ll in a manner described in Patent Number 2,552,153 to W. Crake, granted. September 4, 1945. Suitable closure means are provided at the top of the well casing 32 around the production tubing H, such for example as a wellhead assembly I3, provided with a short section of tubing Hi and a gland it which closes the upper end of tubing M in a fluidtight manner.

The upper end of the production tubing H is closed by a stufiing box or sealing gland it which is adapted to pass a wire line or ribbon strip i7 therethrough and. into the tubing H. Below gland it a T It having an elbow i9 connected thereto, may be inserted in the tubing H to provide means for leading oil or other fluid from the top of the tubing. Conduit 29 is then attached to elbow l9 for leading the production fluid to suitable storage facilities (not shown).

In order that the production tubing I! may be rotated, for purposes to be described later, while the pipe connections l8 and I 9 and conduit 253 at the top of said tubing ll remain stationary, a swivel joint 2i is provided in the production tubing below the T 18. Any well known type of apparatus such as'a supporting swivel 33 and ratchet device 22 is provided for rotating the tubing H. As shown in Figure 1, a ratchet wheel 22 may be fixedly attached to the outside of tubing ii at a point below the swivel joint 2 I. A spring-loaded ratchet or pawl 23 is affixed to the tubing ii for actuating the ratchet wheel 22. The pawl 23 in turn may be actuated by a cable 24 which is secured to the pawl 23 at one end and at the other end to the walking beam of a well pump assembly (not shown) positioned adjacent the well.

Secured to one end of the walking beam 25 of the pumping assembly is an arc-type beam hanger or horsehead 26 having a preferably recessed arcuate outer surface 2'! in which a pair of wire ropes, 28 and 2.9 are movably positioned (Figure 2). The

ropes

28 and 29 are anchored at the upper ends thereof in a pair of sockets 30 and 3! which are in turn afiixed to the horsehead 26. The lower ends of the ropes 2S and 28 are fixedly attached to a cross bar or yoke member 32 which is secured around the production tubing ll below a stop member 33,. The stop member 33, which may include a rotatable bearing on which the tubing I! is supported, in turn is aflixed to the outer wall of the tubing ii either above or below the swivel joint 2 I.

With the above-described construction it may be seen that the normal rocking motion of the walking beam '25 and horsehead 26 will alternately raise and

lower ropes

23 and 25, yoke 32 and production tubing H. At the same time, each rocking motion of the walking beam 25 will cause cable 24 to move the spring-loaded pawl 23 with respect to the ratchet wheel 22 so that the latter is slowly turned in a horizontal plane through bearing in 33 together with the production tubing H to which it is affixed. Swivel 2! causes fittings l8, l9 and 20 to remain stationary in a horizontal plane.

Positioned adjacent the well head assembly [3 is a mast or pole 34 having mounted at its upper end a pulley 35 over which passes wire line ll. A drum 36 on which the wire line or ribbon I! may be reeled is secured by means of a suitable bracket 31 near the lower end of the mast 34. The drum 36 may be rotated by a hand crank 38 or any other suitable prime mover means for reeling the wire line I? in or off the drum 38 at whatever speed desired. One form of prime mover means may comprise a ratchet wheel 39 affixed to one side of the drum 36 with an automatic ratch tin d vice, iagrammatically represented at 40, mounted on bracket 3'! for rotating the ratchet wheel 39 and drum 36. The ratcheting device 69 may in turn be periodically actuated by a cable 4| secured to the walking beam 25 of the pumping assembly. In the embodiment illustrated in Figure 1, the mast 34 is held stationary with respect to the reciprocating and rotating mechanism by a bracket 42.

The wire line I! may be of any cross-sectional shape, for example, square, round, hexagonal, fiat rectangular, or the like. In operation, a small sinker bar 43 is secured to the lower end of the wire line I"! and serves to maintain a fixed tension on said line. If desired, the sinker bar 43 may be provided with a plurality of radially or laterally extending cutting knives 44 of any suitable type. Preferably, the sinker bar 43 is positioned at a predetermined depth within the production tubing I I. During pumping operations, the production tubing H is raised and lowered a few feet with each stroke of the pump. At the same time the interaction of ratchet wheel 22 and pawl 23 slowly rotates the production tubing with respect to the wire line Since the stuffing box It does not rotate and passes freely about the wire line ll, the latter is neither reciprocated nor rotated at any time.

The reciprocating and/or rotating action of the production tubing H causes the wire line I? to act as a cutting means or knife, scraping any parafiin from the interior wall of the pro- 4 duction tubing H at it forms thereon. Since, as a practical matter, an oil well is never perfectly straight, the production tubing II will generally be at some small angle to the vertical which will cause the wire line I! to rest against the wall of the tubing H as it reciprocates, thus scraping 01f the paraffin. Since certain portions of the wire line I l scrape along the low side wall of the inclined production tubing ll, other portions of the wire line in tension are caused to vibrate in a manner so as to cut away suincient amounts of parafiin accumulations over the entire length of the production tubing i7, thus permitting the free flow of oil therethrough. The vibrating wire line also tends to agitate the fiow stream in the production tubing 1 i whereby particles of paraffln in the flow stream are maintained in suspension rather than settling out onto the wall of the production tubing. For cleaning production tubing in the above manner, it has been found that especially good results have been obtained by employing a wire line having sharp longitudinal edges, such as a line made of flat ribbon steel, rather than a round wire.

If desired, in addition to the production tubing being continuously rotated, the wire line H may be slowly reeled up out of the well casing 12 onto the drum by means of the ratchet wheel 39 and its actuating device 40. During the travel of the sinker bar 43 from the bottom to the top of the well casing, the knives 44 on the sinker bar 43, as well as the wire line H, scrape along the inner wall of the production tubing and remove paraffin accumulations therefrom. The sinker bar may be returned to the bottom of the well casing in any suitable manner. For example, when the sinker bar has been raised to the top of the production tubing I I, any increase in tension on the wire line may automatically release or reverse in well known manner the ratcheting device 40 and allow the wire line I! to unwind from the drum 36 and return the sinker bar 43 to the bottom of the production tubing again. The Well in the meantime is being continuously pumped as. it is cleaned.

In Figure 3, the present paraihn scraper is shown in a flowing well to remove paramn accumulations from the interior of a production tubing 5| positioned within a well casing 52 which is closed at the top in a fluidtight manner by a suitable closure means such as a stuffing box 53 mounted above the wellhead 54.

As shown in detail in Figure 4, the stoning box 53 may comprise a cylindrical housing 16 having an annular bearing support H fixedly secured to the inner wall of said housing. A bearing 72 is mounted on said annular support H and a slip bowl 13 is positioned on the top plate of bearing 12, rotatably therewith. A plurality of wedgeshaped slips i4 fit slidably within the slip bowl 73, said slips having toothed or serrated surfaces for gripping the production tubing '51 which passes therethrough. The top of the housing I0 is closed in a fiuidtight manner by packing rings '35 adapted to be compressed by a gland 2'6 and screw-threaded gland nut 11.

The production tubing 5! extends through the stufiing box 53 and is closed at the top in a fluidtight manner by a seal or gland 55 adapted to pass a wire line 56 therethrough.

Below gland 55, the production tubing 5| is provided with a T 5? and conduit 58 for discharging fiuid from the tubing. A swivel 59 is located in the tubing 5! whereby the portion of the tubing below said swivel 59 may be rotated while the portion of the tubing above said swivel remains stationary. A suitable drive wheel or gear 55 is affixed to the outside of the production tubing 5! at any point below the swivel 55. Any suitable mechanical, electrical, pneumatic or hydraulic prime mover means 6! may be connected through suitable transmission means, as through a worm gear 52, to drive gear 6!; and rotate the production tubing 5! The wire line 55 is suspended in the well in manner similar to that described with regard to the embodiment of Figure 1. In the embodiment shown in Figure 3, a platform 53 is mounted on the wellhead and in turn supports the prime mover es and a mast E4. The wire line is reeled on a drum 55 which is secured to the mast, said wire passing over a pulley 66 at the top of the mast and down into the production tubing 5!. Tension is maintained on the wire line 56 by a sinker bar 6? secured to its lower end, said sinker bar being equipped with parafiin cutter knives 68, if desired. Thus, it is seen that the wire line 58 remains substantially stationary while the production tubing til is rotated so that the relative movement between the tubing and the wire line the paraffin from the inside of the tub ing. In operation, the production tubing 5! is rotated very slowly, for example, one or more revolutions a day depending upon the well conditions. Alternatively, the scraper wire line may be mounted so that it is driven by a motor and rotates while the production tubing remains stationary. Parafiin removed by the scraping wire line is carried up the production tubing by the fluid below.

Rather than maintaining an excess of wire line stored on a drum 65 with the wire line passing over pulley es and through gland 55 as shown .u ure a predetermined length of wire line, ufficient to position the bar 43 at a level below that at which deposition of paraffin begins, may

employed, as shown in Figure 5. In this emscribed with. regard to Figure 3.

In the embodiment of Figure 5, the wire line is fixedly secured in a closed hanger head 88 is immovably positioned above T 5?. As in Figures 6 and 7, the hanger head 39 comprise a cylindrical body member 85 havg portion of its bore 82 tapered to form an a ar shoulder 83. A. wire line 86 is fixedly ed, as by rivets 85, to a block member 35 of a adapted to fit within the bore 82 of the body 5! and seat on the internal shoulder 83. e ably, the wire line t l is a length of steel tape aiiixed to the block 86 to one side its vertical axis in a manner such that both of the ribbon tape scrape along the wall of the production tubing 5! as the latter is rotated. The top of the cylindrical body member iii may be closed by a screw-threaded plug 2', which may be provided with a raised portion 2 8 alapted to fit a wrench or clutch. The block =6 be provided with a threaded hole or keyway 89 to facilitate its removal from body Ell.

may be readily seen, as shown in the em- "-nt of the present apparatus illustrated in that a scraper wire line may be mounted rotation in a production tubing 9| which is ed in a well casing er in a stationary posi tion. The production tubing 9i passes up through a well head 93 and tubing head 9 to a '2 as where the oil produced is lead on through a conduit 96. A swivel joint 91 is secured to the 6 top of the production tubing 9! with a wire line hanger head 98 being mounted above the swivel joint 97.

The hanger head 98 is similar to the one described with regard to Figures 6 and 7. In this embodiment, the clutch jaw 99 at the top of the hanger head 98 is adapted to fit in a drive clutch liiii secured to the end of a shaft ill! by a motor 102 through a reduction gear mechanism 583. The motor )2 and reduction gear mechanism H33 are mounted on a suitable platform lEi l above the well head 93. In operation the motor m2 rotates shaft mi and hanger head 93 whereby the wire line suspended from the hanger head 98 within the stationary production tubing 9! is rotated around the inner wall of the production tubing so that any parafiin accumulations are scraped therefrom.

In the embodiment of Figure 8 the tubing head E l may be constructed in a manner illustrated in Figure 9 wherein the head 94 comprises a tubular body 5 d5 having an annular shoulder it formed on the inner wall thereof. A plurality of wedge-shaped slips I al are seated on shoulder lilii to hold the production tubing si in a fixed position. The top of the tubular body Hi5 may be closed by rings of packing I98, a gland we and a gland nut I I6.

I claim as my invention:

1. An apparatus for removing deposits from the inside of a well tubing, said apparatus con prising a wire line in suspension within said well tubing, sealing means closing the upper end of said well tubing and supporting the wire line therein, a weight secured to the lower end of said wire line to maintain a predetermined tension thereon, swivel means connected into said tubing permitting relative rotational movement between the tubing sections above and below said swivel means connection, gear means exteriorly affixed to said production tubing below said swivel means, prime mover means for actuating said. gear means and rotating said lowering tubing section to cause relative movement of said wire line with respect to said tubing, whereby the displacement of said wire line around the inner walls of said production causes the wire line to scrape any deposits therefrom.

2. An apparatus for removing deposits from the inside of a well tubing, said apparatus comprising slip means for supporting said well tubing within a wellhead, bearing means positioned within said wellhead below said slip means for rotatably mounting said tubing in said wellhead. a wire line in suspension within said well tubing, sealing means closing the upper end or well tubing and supporting the wire line therein. a weight secured to the lower end of said wire line to maintain a predetermined tension thereon, swivel means connected into said tubing permitting relative rotational movement between the tubing sections above and below said swivel means connection, gear means exteriorly to said production tubing below said swivel means, and prime mover means for actuating said gear means and rotating said lowering tubing section and causing relative movement of wire line with respect to said tubing whereby the displacement of said wire line around the inner walls of said production causes the wire line to scrape any deposits therefrom.

3. An apparatus for removing deposits from the inside of a well tubing, said apparatus comprising a wire line in suspension within said well tubing, said wire line having the shape of an elongated steel ribbon tape, sealing means closing the upper end of said well tubing and sup porting the wire line against the inner wall thereof, a weight secured to the lower end of said wire line to maintain a predetermined tension thereon, swivel means connected into said tubing permitting relative rotational movement between the tubing sections above and below said swivel means connection, gear means exteriorly aimed to said production tubing below said swivel means and prime mover means for actuating said gear means and rotating said lowering tubing section and causing relative movement of said wire line with respect to said tubing whereby the displacement of said wire line around the inner walls of said production causes the wire line to scrape any deposits therefrom.

4. An apparatus for removing deposits from the inside of a well tubing, said apparatus com-- prising a wire line in suspension within said we 1 tubing, said wire line having the shape of elongated steel ribbon tape, sealing means closing the upper end of said well tubing and supporting the wire line against the inner wall thereof, a weight secured to the lower end of said wire line to maintain a predetermined tension thereon, swivel means connected into said tubing permitting relative rotational movement be tween the tubing sections above and below said swivel means connection, discharge fluid conduit means in communication with said tubing below said swivel means, and prime mover means mounted above the sealing means of said well tubing and operatively connected thereto to rotate said upper tubing section causing relative movement of said wire line with respect to said lower tubing section whereby the displacement of said wire line around the inner walls of said tubing causes the wire line to scrape any deposits therefrom.

5. An apparatus for removing parafdn deposits from a well production tubing having a stream of oil flowing therethrough, said apparatus comprising sealing means at the top of said well tubing adapted to pass a wire line therethrcugh into the bore of said tubing, a wire line suspended in said tubing, means adjacent the top of said tubing supporting said wire line, a weight aiiixed to the lower end of said wire line for maintaining said wire line in tension, a reciprocating pumping assembly positioned adjacent the upper end of said tubing, swivel means connected into said tubing permitting relative rota tional movement of the tubing sections above and below said swivel means connection, means connecting said pumping assembly and said tubing permitting rotation of said tubing on one side of said swivel means with respect to the tubing on the other side, and means positioned adjacent the upper end of said tubing below said swivel means for rotating said tubing about said wire line, whereby said wire line is caused to scrape the walls of said tubing to remove parafin deposits therefrom.

6. An apparatus for removing parafiin deposits from a well production tubing having a stream of oil flowing therethrough, said apparatus comprising sealing means at the top of said well tubing adapted to pass a wire line therethrough into the bore of said tubing, a wire line suspended in said tubing, means adjacent the top of said tubing supporting said wire line, a weight amxed to the lower end of said wire line for maintaining said wire line in tension, a reciprocating pumping assembly positioned adjacent the upper end of said tubing, means connecting said pumping assembly and said tubing for reciprocation of said tubing, swivel means in said tubing permitting rotation 'of said tubing on one side of said swivel means with respect to the tubing on the other side, and tubing-actuating means positioned adjacent the upper end of said tubing below said swivel means for rotating said tubing about said wire line, whereby said wire line is caused to scrape the walls of said tubing to remove paraffin deposits therefrom, said tubing actuating means comprising a ratchet wheel afiixed to said tubing below the swivel means, pawl means engaging said ratchet wheel for the actuation thereof, and cable means secured between said pawl means and the pumping assembly whereby said pawl means and cooperating ratchet wheel are actuated on each stroke of the pumping assembly.

7. An apparatus for removing deposits from the inside of a well tubing, said apparatus comprising a wire line in suspension within said well tubing, sealing means closing the upper end of said well tubing and supporting the wire line therein, a weight secured to the lower end of said wire line to maintain a predetermined tension thereon, swivel means connected into said tubing permitting relative rotational movement of the tubing sections above and below said swivel means connection, and prime mover means positioned adjacent said well tubing above said swivel means and operatively connected thereto to rotate said upper tubing section for causing relative movement of said wire line with respect to said tubing, the displacement of said wire line around the inner walls of said tubing causing the wire line to scrape any deposits therefrom.

8. An apparatus for removing deposits from the inside of a well tubing, said apparatus comprising sealing means for closing the upper end of said well tubing, a wire line passing vertically through said sealing means into said well tubing, means adjacent the top of said tubing supporting the wire line therein, a weight secured to the lower end of said wire line to maintain a predetermined tension thereon, swivel means connected into said tubing permitting relative rotational movement between the tubing sections above and below said swivel means connection, and prime mover means positioned adjacent said well tubing below said swivel means for rotating said tubing section below said swivel means for causing relative movement of said wire line with respect to said tubing, the displacement of said wire line around the inner walls of said tubing causing the wire line to scrape any deposits therefrom.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 982,652 Wiechmann Jan. 24, 1911 1,662,984 Scott et al Mar. 20, 1928 2,179,814 Conaghan Nov. 14, 1939 2,182,680 Rugg et al Dec. 5, 1939 2,278,067 Emery Mar. 31, 1942 2,294,061 Williamson Aug. 25, 1942 2,383,934 Crake Sept. 4, 1945 2,471,198 Cormany May 24, 1949 2,552,939 Condra May 15, 195i FOREIGN PATENTS Number Country Date 703,369 France Feb. 3, 1931