US3267872A - Oil well pump - Google Patents

Description

Aug. 23, 1966 P. s. BLOUDOFF OIL WELL PUMP Filed May 5, 1964 INVENTOR.

PB TEE 5. EL 01/170.

ATTYB United States Patent 3,267,872 OIL WELL PUMP Peter S. Bloudolf, Whittier, Calif, assignor to Armco Steel Corporation, Middletown, Ghio, a corporation of Ohio Filed May 5, 1964, Ser. No. 364,973 1 Claim. (Cl. 103179) This invention relates to oil wells pumps of the type that are inserted in the well and operated by mechanical reciprocation through a string of sucker rods and is particularly directed to an improved setting for a pump known in the industry as a ratio-compound pump.

A ratio-compound pump is used where foamy oil or high gas-oil ratios are present in the pumped fluid. In general the known pump units have been of the insert type wherein the complete pump assembly is inserted with the sucker rods. This apparatus has the disadvantage of limiting the pump bore size that can be used in any given tubing size. If the pump can be set as a tubing pump, its capacity can be increased because of the increased diameter available for the barrel and plunger. Therefore, a primary object of the invention is to provide a ratio-compound pump apparatus which can be set and operated directly in the tubing.

Another object of the invention is to provide apparatus for setting a ratio-compound pump including means to drain the tubing when the pump is pulled for repair or renewal of any of the parts.

Another object of the invention is to provide a pump seal which'cooperates directly with the wall of an oil well tubing to effectively seal the operating spaces of a ratiocompound pump and which can be forced into and out of position by a predetermined movement of the pump plunger, but which will remain in place during normal pumping operation.

Other objects and advantages of the invention will become apparent from the following detailed description of a preferred embodiment thereof, reference being bad to the accompanying drawings, in which:

FIG. 1 is a central, vertical, sectional view of an oil well pump set in accordance with the present invention, with parts broken away to foreshorten the view; and

FIG. 2 is a somewhat enlarged cross-sectional view of the parts between lines 22 of FIG. 1.

The drawings show a preferred embodiment of the invention which comprises an oil well pumping apparatus adapted to be set in a well tubing that has previously been prepared with a standing valve and a pump barrel at the lower end thereof. The apparatus of the invention comprises a seal member that is insertable in the tubing and that has a releasable, preferably frictional engagement with the adjacent wall of the tubing that requires a greater force for displacement than is exerted by the combined upward forces on the pump plunger during normal pump operation. The seal member has an upwardly facing shoulder and the pump plunger carries means engageable with said shoulder to force the seal member downwardly in the well to a predetermined location above the pump barrel. The plunger has a spaced, oppositely facing shoulder adapted to engage the seal member when the pump is removed from the well so that the seal member is forcibly removed as the pump plunger is removed.

In preparing the pump assembly at the bottom of the tubing, a perforated nipple is set in the tubing section immediately over the pump barrel and the perforations thereof are sealed off when the seal member is in place. However, when the seal member is removed from the well by removal of the pump plunger, the perforations of the nipple are exposed so that the tubing may be drained when the pump plunger is pulled.

3,267,372 Patented August 23, 1966 Referring to the drawings, the present invent-ion is shown in con-junction with an oil well tubing 10 and includes a bottom assembly coupled to the tubing by an upper cup shoe 12. A perforated nipple having an opening 13 in its side wall is attached to the cup shoe 12 by a coupling 14 at its upper end, and at its lower end is attached by a coupling 1 5 to a tubing-full barrel 16. This pump barrel is essentially the same diameter as the tubing 10 and thus has the maximum capacity which the space available will permit.

At its lower end the pump barrel carries a standing valve shell 1-7 within which is a conventional stand-ing valve cage 18 and the usual ball check 19 within the cage.

The plunger of the pump comprises a hollow cylindrical body 21 slidably fitted within the barrel 16 and carrying a bottom valve cage 22 within which a lower traveling valve 23 is disposed through which fluid enters on the down stroke of the pump, as hereinafter described.

At its upper end the plunger 21 carries a fluid crossover 24 having a plurality of radially disposed openings or holes 25 therein which communicate with a fluid annulus 26 within the barrel 1'6 and above the plunger into which foamy oil is discharged and compressed during operation of the pump.

Fluid is discharged from the pump through an upper traveling valve 27 carried in a valve cage 28 at the top of the crossover 24.

The plunger assembly including the pump plunger 21 is reciprocated by a string of sucker rods R connected by a conventional coupling 28 having a lower shoulder 29. The coupling 28 connects to a hollow polish rod 30 which carries oil from the pump chambers to the interior of the tubing through a series of sand-eliminating discharge ports 31 and through the major discharge ports 32 at 1ts top.

The present invention is primarly concerned with the inclusion in the combination of an insertable and removable seal assembly shown in a somewhat enlarged form in FIG. 2. The seal assembly may be temporarily set and engaged with the remainder of the parts by any suitable means, and in the preferred embodiment of the invention the releasable engagement is a frictional coaction of the parts. The preferred form of the seal assembly includes an upper seal mandrel 40 having an upwardly facing shoulder 41 thereon which cooperates with the shoulder 29 on the plunger coupling 28 of the reciprocating plunger assembly in a manner hereinafter described during the setting of the seal. A series of flexible cops 42 are carriedon the mandrel 40 and are held in place by a follower ring 43 and a coupling nut 44 which is screwed to the mandrel at its lower end.

The coupling nut 44 also carries an elongated polish rod barrel 45 which fits closely around the rod 30 and prevents the bypassing of oil during reciprocation of the plunger assembly by sealing with the exterior of the polish rod.

At its lower end the barrel 45 carries a coupling 46 to which a lower seal mandrel 47 is attached. The lower seal mandrel carries a series of friction rings 48 and a second series of lower flexible sealing rings 49 which engage in the interior of the pump barrel 16 at its upper end when the parts are in operating position.

The lower mandrel has a lower downwardly facing shoulder 50 which engages a shoulder 51 on the plunger body when the sealing elements are removed from the well.

The elements so far described operate, when set, as a ratio-compound pump. On the upstroke, fluid enters the pump in the normal manner past the standing valve 19 and into the barrel 16 below the plunger 21. At the beginning of the down stroke, the upper traveling valve 27 seats immediately and the pressure is reduced in the an nulus 26 above the plunger while the pressure is increased in the full area below the plunger. This leads to the ratio-compound operation and to the very desirable result that the intermediate traveling valve 23 will open immediately at the start of the down stroke even in a fluid having a high gas-oil ratio. Fluid then passes from the barrel 16 into the hollow plunger and through the crossover ports 25 into the annulus 26.

In a conventional pump, operating at, for example 25 percent efliciency, nearly three-quarters of the down stroke will be completed merely compressing gas before the traveling valve opens.

The increased efficiency of the ratio-compound pump, as known, is brought about both by elimination of gas lock from the compounding action of the two valve controlled chambers comprised by the interior of the plunger 21 and by the annulus 26, and by the more eflicient transfer of fluid and gas from the chamber below the plunger to the annular chamber 26 during the down stroke. This permits the standing valve 19 to open promptly at the beginning of the upstroke, during which time the gassy fluid is being compressed in the annular chamber 26, and the pump chamber below the traveling valve 23 fills more completely with the mixture of gassy oil that is drawn in on pump suction. On the upstroke, valve 23 closes and valve 27 opens. The fluid thus passes from the annulus 26 back through the crossover ports 25 and into the hollow polish rod and hence to the tubing space above the pump.

The seal elements brought into the combination by the present invention define the upper limits of the annular chamber 26 which are a normal part of a ratio-compound pump.

These seal elements are mounted on the pump plunger assembly at the surface and are lowered into the well and forced downwardly by the sucker rods 27 by engagement of the downwardly facing shoulder 29 on the plunger coupling with the upper shoulder 41 of the seal assembly. When the parts comprising the seal reach the upper cup shoe 12, movement is continued therethrough until the upper mandrel 40 seats on a tapered surface of the upper cup shoe 12. At this time, the flexible seal rings 42 will be seated within the interior of the upper cup shoe, and the lower series of flexible seals 49 will be seated within the upper portion of the pump barrel 16. The combined frictional effect of the flexible seals 42, 49 and of the friction rings 48 is such that there is a greater resistance to upward movement required for their displacement than can be generated by the normal pressure difference that might exist within the annulus 26 and the well tubing which would tend to displace the seal parts in an upward direction.

After the seal parts have been seated as above described, reciprocation of the pump plunger can begin in a normal manner by the sucker rods 27 and the seal elements will remain in place.

When it is desired to remove the pump plunger for valve renewal or inspection, the shoulder 51 on the pump plunger will engage the lower shoulder 50 on the lower seal mandrel, and the parts may be forcibly lifted to the surface by the sucker rods 27.

During the lifting of the pump, the tubing will drain as soon as the lower seal elements 49 have passed the upper limits of the shoe 12. This will expose the entire interior of the tubing to the interior of the perforated nipple, and oil will drain out through the openings 13 therein. It is therefore not necessary to bring to the surface all of the oil that would be otherwise trapped over the plunger.

While the invention has been shown in conjunction with a specific form and disposition of the parts, it should be expressly understood that numerous modifications and changes may be made therein, without departing from the scope of the appended claim.

What I claim is:

A sucker rod operated oil well pumping apparatus adapted to be set in a well tubing having a standing valve and a pump barrel at the lower end thereof comprising, a pump plunger, a polish rod interposed between said pump plunger and its operating sucker rods, a seal assembly surrounding said polish rod and comprising spaced seal elements and an intervening polish rod barrel, said seal assembly having an upper shoulder, means carried by said sucker rods and engageable with said seal shoulder to force said seal assembly downward in said pump to a predetermined position with respect to said pump barrel, means carried by said seal assembly to engage the wall of said pump barrel in said predetermined position, a perforated nipple disposed immediately over said pump barrel, the perforations of said nipple being sealed off when said seal assembly is in said predetermined position, and opened when said seal assembly is removed to facilitate drainage of said tubing as said pump plunger and seal assembly are taken out of the well, and a spaced, oppositely facing shoulder on said pump plunger adapted to release said seal assembly when said pump is removed from the Well to forcibly remove said seal assembly as said pump plunger is removed.

References Cited by the Examiner UNITED STATES PATENTS 4/1928 Patterson -a 103-179 7/1956 Hill 103-221

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