US3456724A - Wash tool for use in wells - Google Patents

Description

July 22, 1969 BROWN 3,456,724

WASH TOOL FOR USE IN WELLS Filed Oct. 12. 1967 2 Sheets-Sheet 1 I N VEN TOR.

BY aw A T T'O/PA/Ey C/C'ERO 6. BROWN July 22, 1969 c. c. BROWN WA SH TOOL FOR USE IN WELLS 2 Sheets-Sheet 2 Filed Oct. 12, 1967 JML;

ATTORNEY 3,456,724 WASH TOOL FOR USE IN WELLS Cicero C. Brown, Brown Oil Tools, Inc., R0. Box 19236, Houston, Tex. 77024 Filed Oct. 12, 1967, Ser. No. 674,921 Int. Cl. E2111 37/00 U.S. Cl. 166-146 Claims ABSTRACT OF THE DESCLOSURE A tool for cleaning screen and other perforate wall sections of wells employing a tubular mandrel connectible into an operating pipe string for movement longitudinally in a well bore, the mandrel having fluid discharge ports disposed between longitudinally spaced, wall-engaging seal elements, and having upper and lower circulation ports controlled by sleeve valves arranged to be opened and closed by movement of the mandrel relative thereto, the bore of the mandrel being provided with a plugreceiving seat at a point below the several ports.

Most oil wells are equipped with production pipe or liners provided with perforations or screen sections located opposite producing formations through which formation fluids may enter the production pipe. In the course of operation of the wells these perforations or screen openings will become plugged with sand, scale, and the like, which reduces the inflow of formation fluids and may completely plug-01f the flow. It is necessary in such cases, therefore, to employ some type of equipment for the purpose of cleaning or washing such screen openings or perforations. As the latter may be incorporated in relatively long sections of the pipe wall, it becomes difficult to efficiently clean such perforations by the use of conventional washing tools.

The present invention is directed to an improved form of wash tool which allows washing a succession of short intervals of the screen or perforated section as the tool is moved downwardly in the pipe.

In accordance with one embodiment of this invention, the tool comprises a tubular mandrel adapted to be connected into an operating pipe string and provided with fluid discharge or wash ports positioned between spacedapart seal elements sealingly engageable with the surrounding pipe wall to confine the discharging wash fluid to the wall section segregated by the spaced-apart seal elements. The mandrel is also provided with upper and lower fluid circulation ports controlled by sleeve valves mounted on the mandrel for movement between portopening and closing positions by relative longitudinal movement of the mandrel. The sleeve valves carry means for frictionally engaging the surrounding pipe wall to permit the relative longitudinal movement of the mandrel, and the upper one of the sleeve valves is provided with a releasable connection to the mandrel initially securing it in the port-open position and releasable to permit movement of the mandrel to the port-closing position by rotation of the mandrel relative to the valve. The mandrel is also provided with a plug-receiving seat at a point below the lower circulation ports to permit closing-off the bore of the mandrel for enabling discharge of fluid under pressure through the wash ports.

The various objects and advantages of this invention tates atent O will become more readily apparent from the following detailed description when read in conjunction with the accompanying drawing which illustrates one useful embodiment in accordance with this invention.

In the drawing:

FIGS. 1A and 1B, together, constitute a longitudinal, partly sectional view of the wash tool shown inside a well pipe;

FIGS. 2, 3 and 4 are longitudinal, partly sectional views which illustrate the positions of the several parts at different stages in the operation of the tool; and

FIGS. 5 and 6 are cross-sections taken, respectively, along lines 55 and 66 of FIG. 1A.

Referring to the drawing, the tool includes a tubular mandrel, designated generally by the numeral 10, carrying means such as threads 11 for securing the upper end of the mandrel to an operating pipe string P. The lower end of mandrel 10 is connected, as by means of threads 11a, to a catcher sub 12 having an internal shoulder 13 in the bore thereof forming a seat for receiving a plugging element adapted to close-off the bore, as will be subsequently described. Catcher sub 12 provided with means, such as the threaded pin 14, for connecting it to a tailpipe section T.

Maudrel 10 is made-up of a plurality of co-axially connected sections comprising the upper valve mandrel 15, an upper seal mandrel 16 connected to upper valve mandrel 15 by means of a collar 17, a wash port section 18 threadedly connected to the lower end of upper seal mandrel 16 and, in turn, connected to a lower seal mandrel 16a. The lower end of the latter is connected by means of collar 19 to the upper end of lower valve mandrel 20, the lower end of which is connected to the upper end of catcher sub 12. These several inter-connected elements are dimensioned to have co-axial bores of sub stantially uniform diameters. Upper valve mandrel 15 has a plurality of radial upper circulation ports 21 and lower valve mandrel 20 has a plurality of similar lower circulation ports 22. Wash port section 18 is provided with a plurality of angularly spaced radial openings 23 which may be arranged in longitudinally spaced-apart rows covering a pipe section of any desired length, which will generally be relatively short. Upper seal mandrel 16 carries one or more resilient, cup-type seal elements 24 and lower seal mandrel 16a carries similar seal elements 25. The upper and lower seal elements are disposed, respectively, above and below the several wash ports 23 and are disposed with their open ends in opposed relation so as to confine fluid discharging from wash ports 23 to the section of the surrounding production pipe or casing C, which is confined between the spaced-apart seal elements. By the use of cup-type seal elements, which are of generally conventional form, it will be seen that fluid under pressure discharging from wash ports 2323 will act to force the seal elements outwardly into tight sealing engagement with the wall of easing C and thereby prevent leakage in either direction past the seal elements, whereby to assure that the wash fluid discharging from ports 23 will be directed with full pressure against the section of the pipe wall confined between the adjacent seal elements.

Upper and lower sleeve valves, respectively designated generally by the letters V and V are mounted on upper and lower valve mandrels 15 and 20, respectively, to control the respective circulation ports 21 and 22. Lower sleeve valve V comprises a tubular body 26 slidably mounted on valve mandrel 20 for relative longitudinal movement thereon between limit stops formed by the lower end of collar 19 and the upper end of catcher sub 12. The bore of body 26 of the sleeve carries longitudinally spaced upper and lower seal packings 27 and 28, respec tively, sealingly engageable with the related valve mandrel, and carries on its outer periphery a plurality of angularly spaced radially movable, wiper blocks 29 urged outwardly into frictional engagement with the surrounding pipe wall by means of springs 30. Packings 27 and 28 are spaced apart a distance such that they will span lower circulation ports 22 and seal off the latter when mandrel 20 has moved downwardly relative to body 26 a sufficient distance, as will appear subsequently.

Upper circulation ports 21 are controlled by sleeve valve V which comprises a tubular body 31 carrying in its bore longitudinally spaced upper and lower seal packings 32 and 33, respectively, sealingly engageable with upper valve mandrel 15 and adapted to span and seal-off upper circulation ports 21 when upper valve mandrel 15 has moved downwardly a sufficient distance relative to valve body 31. The latter also carries angularly spaced, radially movable wiper blocks 34 urged outwardly by springs 35 to frictionally engage the surrounding pipe wall. The lower end of body 31 carries a tubular cage 36 having a plurality of openings 37 in the wall thereof and enclosing a split nut 38 provided with internal left-hand threads 38a engageable with a complementary thread section 39 on the exterior of the lower portion of valve mandrel 15. The lower ends of the segments of the nut 38 carry downwardly projecting lugs 40 engageable in slots 41 formed in the lower end of cage 36 to prevent relative rotation between the nut and the cage. The lower end of the latter is formed with clutch teeth 42 co-operating with complementary clutch teeth 43 carried by the upper end of collar 17, the purpose of which will be subsequently described.

In operation, the tool, assembled as shown in FIGS. 1A and 1B and in FIG. 2, will be lowered into pipe P which is provided with a perforate screen section S opposite an earth formation F (FIGS. 3 and 4). As the tool string enters casing C, the frictional engagement of wiper blocks 29 of the lower sleeve valve V will permit mandrel and the parts supported thereon to move downwardly relative to this valve so as to place lower circulation ports 22 between packings 27 and 28 and close the lower circulation ports, the downward movement of ports 22 being limited by engagement of the lower end of collar 19 with the upper end of valve body 26, as seen in FIG. 3.

At this stage of operation, as the releasable connection formed by nut 38 and threads 39 on the upper valve mandrel is still engaged, upper circulation ports 21 will remain open despite the frictional engagement of wiper blocks 34 with the wall of casing C. As the tool string proceeds downwardly through the bore of casing C fluid in the casing will be displaced through the bores of the tail pipe and of the composite mandrel and will be discharged through upper circulation ports 21 into the bore of easing C above the upper seal elements 24, thereby allowing the tool string to move freely down the casing.

As the wash section 18 approaches the uppermost interval of screen S, a plug 45, of any suitable and generally conventional design, will be dropped through the bore of the operating pipe string and thence through the bore of mandrel 10 until it comes to rest on seat 13 (FIG. 4).

The operating pipe string will now be rotated to the right or in the clockwise direction, thereby causing threads 39 to be released from nut 38 which will be held stationary in cage 36 by reason of the engagement of lugs 40 iii slots 41, and thereby permit unscrewing of upper valve mandrel from nut 38 to allow the mandrel and the parts thereon to move downwardly relative to upper valve V to a position closing upper ports 21, as seen in FIG. 4. With the upper and lower circulation ports closed and the bore of the mandrel closed off by means of plug 45, wash fluid, under pressure, may now be pumped through the bore of the tool and discharged through wash ports 18 from which the discharging fluid will be directed by the confinement provided by upper and lower seal elements 24 and 25, into and through the perforations of screen S which are opposite the wash ports and confined between the seal elements. The full fluid pressure of the wash fluid may thus be exerted to clean the openings in screen S and the entire tool string may then be gradually lowered across the face of the screen so as to wash successive intervals of the screen as the tool moves downwardly thereover. As the upper seal elements 24 move downwardly along the face of screen S, fluid entering formation F through the screen perforations being cleaned, will be able to flow back into casing C above the upper seal elements 24 and return to the surface, thus providing circulation for the wash fluid. However, because these perforations passing above the seal elements will be sealed off from those below, the latter will be effectively washed, since the wash fluid must pass through the latter into the formation before it can return past the upper seal elements.

When it is desired to withdraw the tool from the well after completion of the washing operation, an upward pull applied to the operating pipe string will pull the mandrel upwardly relative to both the upper and lower sleeve valves V and V thereby returning both the upper and lower circulation ports to the open positions shown in FIGS. 1 and 2. This will allow the tool string to be pulled out of the well without carrying a load of fluid inside the bore of the string.

The clutch arrangement provided by teeth 42 and 43 is employed to prevent backing-up of the mandrel string inside nut 38 and freezing the latter, because such reverse rotation will be stopped by engagement of the clutch teeth at a point before such excessive threading action occurs.

While the preferred form for sealing elements 24 and 25 is of the flexible cup-type illustrated, it will be evident that other conventional lip-type seal elements well known to .those skilled in the art may be substituted therefor, it being only necessary that they be arranged to prevent fluid leakage in either direction past the seal elements when pressurized fluid is being discharged from wash ports 18.

It will be understood that various other modifications and changes may be made in the details of the illustrative embodiment within the scope of the appended claims but without departing from the spirit of this invention.

What I claim and desire to secure by Letters Patent is:

1. A wash tool for wells, comprising,

(a) a tubular mandrel connectible into an operating pipe string,

(b) longitudinally spaced seal elements mounted on the mandrel for sealing engagement with a surrounding well wall,

'(c) fluid discharge ports in the mandrel between the seal elements,

(d) upper and lower circulation ports in the mandrel respectively above and below said sealing elements,

(e) upper and lower sleeve valve slidably mounted about the mandrel for opening and closing said circulation ports in response to relative longitudinal movement of the mandrel,

(f) means carried by said valves for frictionally engaging the surrounding well wall whereby -to permit said relative longitudinal movement of the mandrel,

(g) latch means initially releasably securing said upper valve to the mandrel in the port-open position and releasable by rotation of the mandrel relative thereto,

(h) a plug-receiving seat in the bore of the mandrel below said lower circulation ports, and

(i) the bore of said mandrel above said seat being uninterrupted and of substantially uniform diameter throughout its length.

2. A wash tool according to claim 1, wherein said seal elements comprise cup-type seals having their open ends disposed in opposed relation.

3. A wash tool according to claim 1, wherein said latch means comprises a segmented nut supported against rotation on said upper valve and having internal lefthand threads engageable with a section of left-han threads on the exterior of said mandrel.

4. A wash tool according to claim 1, wherein each of said sleeve valves includes a tubular body, and longitudinally spaced annular seal packings mounted in the bore of said body in slidable sealing engagement with 15 gaging the surrounding well wall includes a plurality of angularly spaced friction blocks mounted about the exterior of the valve body and spring means urging said blocks toward the well wall.

References Cited UNITED STATES PATENTS 2,210,245 8/1940 Kimmel 166-146 2,426,164 8/1947 Breukelman 166-146 2,569,437 10/1951 Baker 166146 2,796,938 6/1957 Lyrics et a1. 166147 3,391,743 7/1968 Bateman 166186 DAVID H. BROWN, Primary Examiner US. Cl. X.R. 166-150, 202

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