US2966121A - Reciprocating well pump sand wiper - Google Patents

Description

Dec. 27, 1960 P. s. CROWL RECIPROCATING wan. PUMP SAND WIPER Filed Jan. 2, 1958 III 0 Z In M n 1 0 8 6 0- .4 a M W w u7// Jr////// 7//// QR.- AN%%///////////////A 4 INVENT OR.

Buzz 8 62901.11 W/ flffOP/Vf) United States Patent C RECIPROCATING WELL PUMP SAND WIPER Paul S. Crow], 3632 NW. 52nd St., Oklahoma City, Okla.

Filed Jan. 2, 1958, Ser. No. 706,603

6 Claims. (Cl. 103-202) This invention relates generally to improvements in subsurface well pumps of the reciprocating type, and more particularly, but not by way of limitation, to an improved sand wiper for such pumps.

As it is well known in the oil industry, crude oil invariably contains at least some sand and other solid particles suspended therein. The majority of oil wells being produced by artificial lifting means are produced by a reciprocating type pump, usually a sucker rod or wire line type pump. In these sucker rod and wire line type pumps, the piston reciprocates in the working barrel of the pump, with a clearance of about .002 to .003 inch between the plunger and the barrel, and the plunger is of sufiicient length that the oil will provide a practical seal of the plunger in the working barrel, whereby the plunger will lift the crude oil through the working barrel and production tubing to the top of the well. Sand suspended in crude oil will invariably settle out of the crude oil standing in the production column above the pump, and a minor portion of the sand will tend to enter the clearance between the plunger and the working barrel to erode the outer periphery of the plunger and the inner periphery of the working barrel. Sand settling from the crude oil has a greater tendency to enter the clearance between the plunger and the working barrel at the upper end of the working barrel, since the highest fluid pressure acting on the plunger is imposed in a downward direction when the plunger is on the up-stroke.

Many prior attempts have been made to prevent the entrance of sand into the space between the plunger and the working barrel of these sucker rod and wire line type pumps. One method which has been proposed is the use of a metal sleeve secured on the upper end of the plunger and having a sharp upper end to scrape sand from the walls of the working barrel on the up-stroke of the plunger. Such metal sleeves remove a portion of the sand from the inner periphery of the working barrel, but a substantial clearance must be provided between the outer periphery of the sleeve and the inner periphery of the working barrel to prevent the sleeve from binding and having a metal-to-rnetal fit with the working barrel. Another popular method of removing sand is by the use of a rubber cup or packing on the upper end of the plunger. Such cups or packers can be made to remove all of the sand from the inner periphery of the working barrel; however, if all of the sand is removed, at least a portion of the oil film on the inner periphery of 'the working barrel is also removed to decrease the lubrication of the outer periphery of the plunger, and substantially reduce the service life of the plunger. If the packer or cups are not pressed tightly against the inner periphery of the working barrel, some of the sand escapes the packers or cups and enters the clearance between the plunger and the working barrel.

The present invention contemplates a novel sand wiper utilizing an elastic member for tightly engaging the inner periphery of the pump working barrel and scraping all of the sand from the inner periphery of the working barrel ahead of the pump plunger movement. The elastic member is supported in spaced relation from the end of the plunger and a filtering means is provided between the elastic member and the respective end of the plunger to provide a flow of clean well fluid outwardly back into contact with the inner periphery of the working barrel where it will provide a seal and suificient lubrication around the outer periphery of the plunger. The filtering means is constructed to permit the outward fiow of well fluid, but prevent the entrance of sand between the elastic member and the respective end of the plunger.

An important object of this invention is to increase the service life of reciprocating type subsurface well pumps.

Another object of this invention is to minimize the entrance of sand between the plunger and working barrel of a subsurface pump, while retaining a fluid seal and film of lubricant around the plunger.

A further object of this invention is to provide a combination sand wiper and filter for a reciprocating type sub-surface pump.

A still further object of this invention is to provide a sand wiper for reciprocating type subsurface well pumps which is simple in construction, may be economically manufactured, and will have a long service life.

Other objects and advantages of the invention will be evident from the following detailed description, when read in conjunction with the accompanying drawings which illustrate my invention.

In the drawings:

Figure l is a vertical sectional view through a portion of a reciprocating type subsurface well pump having my novel sand wiper assembled therein.

Figure 2 is an elevational view of the sand wiper.

Figure 3 is a sectional view as taken along lines 33 of Fig. 2.

Figure 4 is an enlarged detailed view showing a typical passageway through the wiper during operation of the pump to provide an outward flow of clean well fluid.

Referring to the drawings in detail, and particularly Fig. 1, reference character 6 generally designates a reciprocating pump (only a portion of which is shown) of the type used below the surface in an oil or water well. The pump 6 includes a tubular working barrel 8 of a size to be inserted in a well tubing (not shown) and having a standing valve (not shown) at the lower end thereof. A tubular plunger 10, having a traveling valve (not shown) therein, reciprocates in the working barrel 8 to pump well fluids upwardly through the working barrel and the tubing string to the surface of the well. Normally, the plunger 10 is made of such a size that a clearance of from .002 to .003 inch is provided between the plunger 10 and the working barrel 8 in order that the plunger 10 may be reciprocated freely in the working barrel. This clearance between the plunger and the working barrel is normally filled with a portion of the well fluid being pumped to provide lubrication around the plunger 10. It may also be noted that although a slight leakage invariably occurs between the plunger 10 and the working barrel 8 on the pumping stroke of the pump, the plunger 10 is sealed in the working barrel 8 for all practical purposes, such that the plunger 10 lifts fluid standing in the working barrel 8 during the upstroke of the plunger. The plunger 10 is reciprocated by a pump rod 12 threadedly secured in the upper end portion of the plunger. I prefer to reduce the outer diameter of the upper end portion of the plunger to accommodate any expansion of the plunger obtained when the rod 12 is threaded therein. Suitable passageways 14 are formed through the connecting member of the rod 12 in the upper end of the plunger to permit upward movement of pumped well fluid through the (not shown) to equipment at the surface of the well to provide reciprocation of the plunger in the working barrel 8. p

In accordance, with the present invention, a sand wiper, generally designated by reference character 16, is secured to the upper end of the plunger 10 to remove sand from the inner periphery of the working barrel 8 ahead of the. plunger 10 on the ,up-stroke of the plunger. It should also be noted, however, that a wiper 16 may also be secured on the lower end of the plunger 10, if desired. The sand wiper 16 comprises a tubular-shaped sectional body formed by a lower rigid, tubular'connector 18 and an uppertubular elastic sleeve 20. The connector 18 has a threaded portion 22 on thelower end thereof for connection with threads in the upper end of the plunger 10. The inner diameter of the connector 18 is of size to loosely receive the pump rod 12, with a substantial clearance between the pump rod and the connector for the passage of pumped well fluid upwardly through the connector. The outer diameter of the connector 18 is of a size to provide a loose fit of the connector in the working barrel 8. It is preferred that the outer diameter of the connector 18 be less than the outer diameter of the plunger 10 to provide an annular passageway 24 between the connector and the working barrel 8. The upper end portion 26 of the connector '18 is tapered inwardly toward the upper end of the connector to receive the lower end portion 28 of the elastic sleeve 20.

The sleeve 26 is formed out of a rubber-like material with elastic and resilient properties, for purposes which will be hereinafter set forth, and is secured around the portion 26 of the connector 18, preferably by bonding the sleeve on the connector. The sleeve 20 should also be formed out of a material which is resistant to action of the well fluid being pumped, and which will not be easily worn away by being rubbed along the inner periphery of the working barrel 8. Although the'sleeve 20 may beformed out of a great variety of materials hav-' ing elastic properties, I prefer to form the sleeve outiof a product sold by Albert Trostel Packin gs Limited of Lake Geneva, Wisconsin, under the trade name of ,Vul-

kollan. This material is highly oil andacid resistant, has good wearing properties, and has a long service life in an oil well environment. 7

As shown most clearly in Fig. 2, the upper end portion 30 of the sleeve 20 is increased in diameter to pro vide an upper tapered end having an outer diameter greater than the inner diameter of the working barrel 8, such that theupper end portion 30 of the sleeve 20 must be compressed when inserted in the Working barrel 8 Thus, the upper end portion 30 of the sleeve 20 will tightly engage the inner periphery 8a of the working barrel and efliciently scrape sand from the inner periphery of the working barrel 8 inwardly into the vertical bore. 32 extending through the central portion of the sleeve. I also prefer that a tapered counter-bore 34 be formed in the upper end 30 of the sleeve 20 concentri- V cally around the bore 32 to facilitate the inward movement of sand scraped from the inner periphery of the working barrel. A plurality of grooves 36 are formed in the outer periphery of the sleeve 20. The grooves 36 are provided in two vertically spaced rows, with the grooves in each row being equally spaced around the sleeve. Vertically adjacent grooves 36 are interconnected by shallower grooves 38 to provide passageways barrel 8 to the upper end of the plunger 10. It may also be noted that the outer diameter of the sleeve 20 below the upper end portion 30 is preferably of a size to provide a free sliding fit thereof in the working barrel 8. In other words, a slight clearance may be provided between the sleeve 20 and the inner periphery of the working barrel 8 along thelength of the sleeve, except for the upper end portion 30 of the sleeve. 'This upper end portion, as previously described, must tightly engage the inner periphery of the working barrel. An I-shaped slit 42 is'cut through the side wall of the sleeve 24} in each of the. deeper grooves 36. The slits 42 are preferably formed in the sleeve 20 without the removal of any material, such that the material around each slit 42 will be flexed when the pressure inside the sleeve varies with respect to the pressure outside of the sleeve. Movement of the material around each slit 42 minimizes the possibility of foreign matter depositing and permanently closing the slits. The slits 42 must be of a size and capable of opening when a pressure differential is applied across the sleeve, as will be more fully hereinafter set forth. When using the productFVulkollan I have found that the grooves 36 should be formed in the sleeve 20 at such a depth that approximately ,5 of an inch of material remains between the bottom of each groove and the inner periphery of the sleeve. However, this dimension is not critical and will of course depend upon the specific material being used, as well as the environment During operation of the pump 6 when using the sand wiper 16, the upper end portion 30 of the sand wiper efliciently scrapes sand from the inner periphery of the working barrel 8 to such an extent that substantially no sand will have an opportunity to contact the outer p eriphery of the upper end of the plunger ill. The sand scraped from the working barrel is diverted into the cerb tral portion of the working barrel where it will be pickedup by fluid being pumped upwardly through the pump 6 and removed from the well. During at least the initial portion of the up-stroke of the plunger 10, the pressure of the fluid standing in the working barrel 8 above the wiper 16 will impose a pressure force on the inner periphery of the sleeve 20. Such increased pressure induces a pressure differential between the inner and outer peripheries of the sleeve, such that the slits 42 are opened in the manenr indicated in Fig. 4 for the flow of well fluids through the slits 42 into each 'of the larger grooves 36. Each slit42 therefore forms a transverse passageway through the walls of the wiper 16 for the outward flow of well fluid below the upper end portion 30 of the wiper,

The sizes of the slits 42 and the thickness of the sleeve 20 within each of the grooves 36 must be correlated, such that the slits 42 will be opened for the passage of fluid, but not opened tosuch an extent that sand can move through the slits with the well fluid. Since the fluid flowing through the'slits'42 flows on downwardly through the grooves 38 and 40 and the annular passageway 24 to lubricate the outer periphery of the plunger 10, the slits 42 should open to provide passageways through the sleeve 20 having a width less than the clearance around the plunger'10 in order to be of any'assistance in reducing the amount of sand which would otherwise contact the outer periphery of'the plunger 10. In pumping crude oil, the slits'42 and the thickness of the sleeve 20, at the bottom of each groove 36 should be such that the slits 42 will open andform passageways having ,r the width of about .0005" inch. '1 have" found that passageways of thiswidth will provide an outward flow of well fluid, but will elfec'tively prevent the flow of sand to the outer periphery of the sleeve which would enter. the clearance between the pump plunger lQband the working'b'arrel Siand cause: damage to the plunger. It may also be noted'that'theslits' 42' are formediman I-shape to provide a substantially uniform opening of the slits when a pressure differential is provided across the sleeve and control the maximum opening of each slit 42.

As clean well fluid flows downwardly from the grooves 36 through the grooves 38 and 40 and the passageway 24 to lubricate the outer periphery of the plunger 10, additional clean well fluid is directed through the slits 42 into the grooves 36. The number of slits 42 provided will, of course, be SHfilClCIlt to provide enough clean well fluid around the plunger to effectively lubricate the plunger and provide a fluid seal of the plunger in the working barrel.

It should also be noted that the pressure differential imposed vertically across the upper end portion 30 of the sleeve 20 will be minor, as compared with the pressure differential across the usual cups which are frequently used on the upper end of a pump plunger, to minimize the wear of the upper end portion 30 of the sleeve and eliminate the possibility of the sleeve 20 being ruptured by excessive pressure diflerentials. The pressure of the fluid in the grooves 36 will be substantially the same as the pressure of the well fluid immediately above the sleeve 20 to at least partially counter-balance the downwardly acting force of the fluid on the upper end of the sleeve.

From the foregoing it will be apparent that the present invention will substantially increase the service life of subsurface well pumps of the receiprocating type. The combination wiper of this invention eifectively scrapes sand from the inner periphery of the working barrel ahead of the plunger and provides a lubricant comprising clean well fluid for the outer periphery of the plunger. The slits of the preferred embodiment form transverse passageways through the wiper of a size to filter sand from the well fluid, but of a sufficient size for the outward flow of the well fluid below the scraper portion of the wiper. It will be further apparent that the present sand wiper is simple in construction, may be economically manufactured and will have a long service life.

Changes may be made in the combination and arrangement of parts or elements as heretofore set forth in the specification and shown in the drawings, it being understood that changes may be made in the precise embodiment shown without departing from the spirit and scope of the invention as defined in the following claims.

I claim:

1. In combination with a reciprocating subsurface well pump used in pumping sandy fluids, having a tubular pump plunger slidingly disposed in a working barrel and cooperating with the working barrel to pump fluid; a sand wiper, comprising a tubular body having one end thereof secured to one end of the pump plunger, with the bore through said body communicating with the bore through the plunger for the passage of sandy well fluid; said one end of the tubular body having an outer diameter less than the outer diameter of the pump plunger; the opposite end portion of said body being solid-walled and formed of an elastic material having an outer diameter, when uncompressed, greater than the inner diameter of the working barrel; said body having transverse passageways through the walls thereof between said end portions thereof; each of said passageways having a width less than the clearance between the pump plunger and working barrel to filter sand from well fluid flowing therethrough.

2. A sand wiper as defined in claim 1 characterized further in that the width of said passageways is about 0.0605 inch.

3. In combination with a subsurface well pump used in pumping sandy well fluids, having a vertically extending working barrel and a tubular pump plunger reciprocating in the working barrel and cooperating with the working barrel to pump fluid; a sand wiper, comprising a tubular, rigid connector secured on one end of the pump plunger with the longitudinal bore through the connector in axial alignment and in communication with the bore of the pump plunger; said connector having an outer diameter less than the outer diameter of the pump plunger to provide an annular space between said connector and the working barrel in communication with said one end of the pump plunger; and an elastic sleeve secured on the end of said connector opposite the pump plunger in axial alignment with said connector; the end of said sleeve opposite the connector being solid-walled and having an outer diameter greater, when uncompressed, than the inner diameter of the working barrel; said sleeve also having a plurality of transverse passageways therethrough positioned between said solid-walled end and said connector; and said sleeve having a plurality of grooves in the outer periphery thereof extending between said passageways and said annular space, each of said passageways having a width less than the clearance between the pump plunger and the working barrel to filter sand from fluid flowing therethrough.

4. A sand wiper as defined in claim 3 characterized further in that said passageways are formed by slits through said sleeve.

5. A sand wiper as defined in claim 3 characterized further in that portions of said grooves are extended through the major portion of the wall thickness of said sleeve, and said passageways are formed by I-shaped slits through said sleeve in said portions of said grooves.

6. A sand wiper as defined in claim 3 characterized further in that said connector is secured on the upper end of the pump plunger.

References Cited in the file of this patent UNITED STATES PATENTS 216,946 Cunningham July 1, 1879 1,295,848 Carmichael Mar. 4, 1919 1,623,543 Jones et a1. Apr. 5, 1927 1,859,672 Masters et a1. May 24, 1932 1,948,325 Anderson et al. Feb. 20, 1934

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