US3070169A - Apparatus for cleaning interior surfaces of pipe strings - Google Patents

Description

Dec. 25, 1962 A. R. HILTON, JR., ETAL 3,070,169

APPARATUS FOR CLEANING INTERIOR SURFACES OF PIPE STRINGS Filed Nov. 29, 1961 INVENTORS.

ALBERT R.HILTON,JR. g:QORACE H. SPAIN,

ATTORNEY.

FIG. 2.

Bfillldfi Patented Dec. 25, 1962 3,070,169 APPARATUS F0. CLEANING INTERIOR SURFACES 9F PIPE STRINGS:

Albert R. Hilton, Jr., Richardson, and Horace H. Spain, Houston, Tex., assignors, by mesne assignments, to Jersey Production Research Company, Tulsa, Okla, a corporation of Delaware Filed Nov. 29, 1961, Ser. No. 155,549 3 Clairns. (Cl. 166-17'7) This invention relates to apparatus for cleaning the interiors of elongated pipe strings such as are used in well installations.

There are many techniques in common use in oil field technology that require the removal from pipe string walls of fluid films or droplets that remain after fluids have been flowed or pumped through the pipe strings. For example, in connection with consolidation of unconsolidated or sandy earth formations surrounding a well bore, it has become the practice to pump through pipe strings into the formation fluids which act to bind together the earth particles making up the formation while maintaining acceptable earth formation porosity. If the fluids used for formation consolidation were allowed to remain clinging to the interior Walls of the pipe string for an appreciable amount of time after the operation has been completed, the liquids would harden and would impede later well operations. Therefore, it is desirable to clean the interior surfaces of the pipe strings, using a device such as a wiper plug, as soon as possible after such liquid materials have been passed therethrough.

Often there arises a need for cleaning the Wall of a well pipe string having an interior diameter that changes at some point along its length. For example, it is common practice to temporarily lengthen a tubing string by lowering a small diameter extension pipe through the tubing string previously in place in the well bore and to land the upper end of the extension pipe in a landing or seating nipple permanently installed at the lower end of the regular tubing. Manifestly, any wiper plug of sufficiently large diameter to clean the interior surface of the upper pipe string will not enter the extension pipe, and any plug small enough to enter the extension pipe will not wipe the Walls of the larger upper pipe string.

In accordance with the teachings of the present invention, there is provided an elongated body member having a bore extending therethrough and having mounted on the outer surface thereof annular resilient wiping means having an outside diameter slightly greater than the inside diameter of an upper section of well pipe to be cleaned. An elongated mandrel is provided having at least a portion of its length turned to an outside diameter no larger than the diameter of the bore through the body member so that the portion of the elongated mandrel can fit into said bore. Resilient wiping means affixed to the outer surface of the mandrel have an outside diameter at least as great as the inside diameter of the lower extension pipe for wiping engagement therewith. The enlongated mandrel is releasably held within the bore of the elongated body member so as to be disconnected from the body member when pressure of predeterminable magnitude is exerted thereon. Thus, the body member and mandrel may be pumped down the upper pipe string until the extension pipe is reached. The mandrel will slip into the bore of the extension pipe, will become disconnected from the body member by the simple procedure of exerting hydraulic pressure thereon, and will be operative to wipe clean the interior surface of the extension pipe.

It is also within the ambit of the present invention to provide a check valve in the bore of the body member above the elongated mandrel operative to oppose fluid flow upwardly through the body member, and to provide a shear pin extending through a port in the body member to engage the elongated mandrel for releasably connecting together the body member and mandrel. The function of the check valve means is to permit retrieval of the body member from the upper pipe string section by the simple operation of pumping fluids down the annulus around the upper pipe string and up the bore of the pipe extension and upper pipe string.

Objects and features of the invention which are not apparent from the above discussion will become evident upon consideration of the following description thereof taken in connection with the accompanying drawing, wherein:

FIG. 1 is a sectional view illustrating a preferred embodiment of the invention;

FIG. 2 is a cross-sectional View taken along section 2-2 of FIG. 1; and

FIG. 3 is a schematic view of a well installation utilizing the apparatus of FIG. 1 for the purpose of illustrating the utility of the invention.

With reference now to FIG. 1, there is illustrated an elongated annular body member 1 having a flanged section '7 at the lower end thereof and provided with interior and exterior threads at the upper end thereof. There is also provided a small opening 16 between the exterior of the body section and its bore for receiving a shear pin, for purposes to be described below. As illustrated, the bore through the body member 1 extends the entire length thereof and is of substantially uniform diameter from the lower end of the body member 1 to a point slightly above the opening 16.

A plurality of resilient annular wiping members 5, which may be of a rubber-like material such as neoprene, are aihxed to the outer surface of the body member 1 and are spaced apart by annular spacers or Washers 3. The spacers 3 and Wiping members 5 are held on the exterior of the body member 1 above flange 7 by a retaining nut 9 screw-threaded onto the external threads at the upper end of the body member 1. The outside diameter of the wiping members 5 is slightly greater than the inside diameter of a pipe to be cleaned thereby so as to be in wiping engagement with the pipe.

A check valve housing 11 is inserted into the bore of body member 1 at the upper end of the body member and is provided with threads to engage the interior threads within the bore of the body member. Within the check valve housing 11 is provided a conventional ball valve member 13 held against a tapered seating sur face within the bore of the housing 11 by a coil spring 15. Such apparatus is well known in the art and will not not be further discussed herein. The function of the check valve is to oppose fluid fiow upwardly through the bore of body member 1 while permitting fluid flow down through the body member upon exertion thereon of sufiicient pressure to overcome the force of spring 15.

An elongated mandrel 23 is provided having an upper portion adapted to slide into the bore of body member 1. The mandrel 23 has a reduced section 2-1 at the upper end thereof so as to receive a shear pin 17 slidable through opening 16 for releasably connecting together the mandrel and the body member. This construction is most perspicuously illustrated in FIG. 2. The lower portion 25 of the mandrel has afiixed thereto a plurality of wiper members 27 spaced apart by spacers 29. The lower mandrel portion 25 has a reduced diameter so asto provide a shoulder for retaining the spacers 29 and Wiping members 27 on the mandrel. A pointed retaining nut 31 is screwed on the lower end of mandrel portion 25 to hold the spacers 29 and wiping members 27 on the mandrel portion 25. The pointed tip on nut 31 is desirable so that the apparatus may be easily insertable into the lower extension pipe 43, to be described below. The outside diameter of wiping members 27 is slightly larger than the inside diameter of the lower extension pipe to be wiped clean thereby.

With reference now to FIG. 3, the utility of the apparatus described with reference to FIG. l and FIG. 2 is readily observed. In FIG. 3 there is illustrated a conventional permanent completion type well installation comprising a casing string 33 cemented to surrounding earth formations, an upper tubing string 35 coextending with casing string 33 from well head apparatus (not illustrated) at the earths surface, and a tubing extension 43 of smaller diameter than tubing string 35. The tubing string 35 is provided with a landing nipple 37 at the lower end thereof. The tubing extension 43 is provided With a radially extensible hanger mechanism 39 adapted to seat in landing nipple 37, and with a resilient packing 41 for conventional isolation purposes. The wiper assembly illustrated in FIG. 1 is driven down the tubing string 35 by liquid or gas pumped into the tubing string behind the assembly. While the assembly is being driven down the tubing string, the check valve in the bore of body member 1 will remain closed. Liquid adhering to the interior surface of tubing string 35 as a result of previous well treating operations will be wiped down the tubing by wiping members 5. When the assembly reaches the upper end of tubing extension 43, mandrel will enter the tubing extension. The hydraulic or pneumatic driving pressure is thereupon increased to open the check valve so that pressure is exerted on the upper end of mandrel 23 to shear the shear pin 17. The mandrel will thereupon be driven through the tubing extension 43 to wipe clean the interior surface of the tubing string. The mandrel is ejected from the lower end of tubing extension 43 and allowed to fall to the bottom of the well. If desired, the mandrel 23 and spacer members 29 may be constructed of aluminum so that they may be dissolved by spotting a caustic or acidic liquid at the bottom of the well, which liquid thereafter may be circulated out of the well.

To remove the body member I from the tubing it is necessary only to reverse circulation of liquids so as to force the body member up the tubing string. If desired, however, a retrieving head or neck 8, shown in dotted lines, may be integrally formed with coupling nut 9 so that a conventional wireline retrieving apparatus may be used to pull the body member and its associated apparatus out of the tubing string.

The invention is not to be restricted to the specific structural details or arrangement of parts herein set forth, as various modifications thereof may be effected without departing from the spirit and scope of this in vention.

Objects and features of the invention having been completely described, what we wish to claim is:

1. For use in a well installation including a well pipe having an upper section with a first inside diameter, and a lower section with a second smaller inside diameter, a pipe wiper comprising:

an elongated body member having a bore extending therethrough, and including an outwardy extending flange at one end thereof, the diameter of said bore being less than the inside diameter of said lower section;

:a check valve at the upper end of said bore for opposing passage of fluids up through said bore;

first annular resilient wiping means carried by said body member above said flange, said wiping members having an outside diameter slightly greater than the inside diameter of said upper section of said well pipe;

annular spacing means on said body member between said wiping members;

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a retaining nut afiixed to said body member at the opposite end from said flange to hold said wiping members and said spacing means on said body memher;

an elongated mandrel having at least a portion thereof adapted to fit into said bore;

second resilient annular wiping means on the lower portion of said mandrel having an outside diameter at least as great as the inside diameter of said lower section for wiping engagement therewith;

second annular spacing means on said mandrel be tween said second wiping means;

a pointed retaining nut aflixed to the lower end of said mandrel for holding said second wiping means and said second spacing means on said mandrel; and

shear pin means holding said mandrel in said body member.

2. For use in a well installation including a well pipe having an upper section with a first inside diameter, and a lower section with a second smaller inside diameter, a pipe wiper comprising:

an elongated body member having a bore extending therethrough, and including an outwardly extending flange at one end thereof, the diameter of said bore being less than the inside diameter of said lower section;

a check valve at the upper end of said bore for o posing passage of fluids up through said bore;

first annular resilient wiping means afiixed to the exterior of said body member and having an outside diameter slightly greater than the inside diameter of said upper section of said well pipe;

an elongated mandrel having at least a portion adapted to fit into said bore;

resilient wiping means alfixed to said mandrel having an outside diameter at least as great as the inside diameter of said lower section for wiping engagement therewith; and

shear pin means holding said mandrel in said body member.

3. For use in a well installation including a well pipe having an upper section with a first inside diameter, and a lower section with a .second smaller inside diameter, a pipe wiper comprising:

an elongated body member having a bore extending therethrough, and including an outwardly extending flange at one end thereof, the diameter of said bore being less than the inside diameter of said lower section;

a check valve at the upper end of said bore for opposing passage of fluids up through said bore;

first annular resilient wiping means affixed to the exterior of said body member and having an outside diameter slightly greater than the inside diameter of said upper section of said well pipe;

an elongated mandrel releasably held within the bore of said body member having at least a portion adapted to fit into said bore; and

second resilient annular wiping means afiixed to said mandrel and having an outside diameter at least as great as the inside diameter of said lower section for wiping engagement therewith.

References Cited in the file of this patent UNITED STATES PATENTS 1,793,644 Segelhorst et al. Feb. 24, 1931 2,188,959 Schaer Feb. 6, 1940 2,257,080 Turner Sept. 23, 1941 2,601,614 Johnson June 24, 1952 2,762,439 Pomeroy Sept. 11, 1956

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