US2687697A - Rod weight compensator for well pumps - Google Patents

Description

Aug. 3l, 1954 .1. B. REILLY ROD WEIGHT COMPENSATOR FOR WELL PUMPS Filed Oct. l1, 1952 s 7 5 2 A Mu J Zhwentor JOHN 5. APE/L Y (tforneg Patented Aug. 3],"1954 John B. Reilly, Whittier, Calif. Application October 11, 1952, Serial No. 314,261 3 Claims. (Cl. 10S-202)` This invention `relates to means to counterbalance or compensate for the Weight of the string of sucker rods to the lower end of which is connected a pump piston or like reciprocating member.

In Wells of relatively shallow depth, the wear on the relatively to abnormally stress the same beyond the ability of the joints in said string,and the rods `themselves, to safely absorb such stress. String breakage is, therefore, infrequent. However, as the depth of the Well increases, the length and, therefore, the weight of the string of sucker rods increases, resulting in materially increased stresses on said string during reciprocation `and more frequent breakage of the string.

In wells 10,000 to 12,000 feet or more deep, the

Weight compensating means.`

A sucker rod string, as mentioned above, op`` erates in tubing `which conducts to the surface It is common the surface to reciprocate `the string. It is a The present means also serves as a vibrationdampening agent and has a clash of general superiority and -serviceability The invention also comprises the Well casing being shown in pump longitudinal section. enlarged longitudinal ventional casing the bottom of the Well 1.

`oil or other liquid lls the Well bottom as, for

Such level may vary but,

. same discharges in valve I6 into the interior I1 of tubing II, and that repeated reciprocations of the plunger will result in the liqud rising in tubing II until the the direction of arrow 9 Thus, in conventional pumps, the string of sucker rods I8 that carries plunger I5 and reciprocates the same, moves through the volume of liquid in the interior I1 of casing II.

The present means" I9- for counterbalancing or compensating for al materialV portion of the weight of sucker rod string I8 is provided in the above-described and generally conventional well pump. While two such meansv are shown in. Fig. 1, only one may be used or, if the well i `s quite deep, more than two may be used. In Fig. 1, the dimensions may each be in the nature of 5000 or 6000 feet and the dimension 2| may be as great or less, as desired. These dimensions are by way of example because the intent is" topro: vide a means I9 at such distance below the well surface that the saine will support a material part of the weight of string I8 to relieve the same of abnormal stresses that may` cause breakage. Mostv deep wells of, for instance, 10,000 to 12,000 feet in depth, may require; but one means |9- to provide support that wouldreduce the stresses in the string to the point where the same is no longer a breakage-causing factor. Still deeper wells may require two or more such means I9 to provide a safe reduction of stresses inthe string I8.

With more particular reference means I9 comprises, generally, a rod 22 interposed in the sucker rod string I8 and, therefore, constituting a part of saidstring, a piston 23 on said rod andof adiametral size to have its lower end 2| materially larger than rod 22 and of substantial area, a cylinder 25 within tubing II and in which piston 23 reciprocates as the string I8 reciprocates, saidA cylinder 25 being to Fig. 2, the

clear of tubing Iy I to provide an annular space 25 therebetween, an anchor 2Ba for the upper end: of cylinder 25 and connecting the same to tubing II, a by-pass 21 around said anchor and communicating the interior I1 of tubing' Il below said anchor with said interior above the anchor, one or more ports 28 through the anchor and tubing and communicating the interior 29 of cylinder 25- above piston 23 with the annular space I2 between casing 5 and tubing II, and abearing 30 for rod 22 that also seals interior 29 from interior I1 above the anchor and bypass.

Rod. 22 with piston 23 thereon comprises a unit which can be incorporated in string I8l by the usual box and pin connections conventionally employed toV connect sucker rods, to form a string.

Cylinder 25 is open at its bottom 3i and is of a length to house piston 23 for the full stroke of string I8 and pump plunger I5.

Anchor 26a comprises a packing body 32 that ts a packing shoe 33 formed on or provided in tubing I I, and two longitudinally spaced packing rings v341 carried by the body and tightly engaged with the shoe. Conical shoulders 35 on said body and shoe locate said anchor, and the cylinder extending downwardly therefrom, longitudinally in tubing Il.

Ports 23 are located between packing rings 34 so that the same are effectively sealed from the interior I1 of tubing II and, therefore, seal said interior from casing space I2` and the upper end 29 of cylinder 25 which said ports connect. BypassA 21 is provided to by-pass around packing Y now contemplate to` be rings 34 and provide communication between interior I1 above and below said packing rings.

Bearing 30 is shown in the form of an elongated stufng box in which packing 33 seals around rod 22.

Since space I2 is under low or atmospheric pressure, the mterior 29 of cylinder 22 above piston 23 is also under such low pressure by reason of` communicating ports. 2'8. All other spaces, namely, interior I1Y (both above and below the anchor), annular space 26, and by-pass 2T, are under the pressure of the liquid being pumped upwardly by pump I0. Since this liquid extends to the surface 6 of the well, the same has a substantial head. Therefore, the lattermentioned spaces are under high pressure in comparison to the low pressure in spaces I2 and 29.

When the string I9 is moved down, the surface 24 of piston 23 encounters the resistance of the head of liquid-,in tubing II. Therefore, the weight of said string; above said piston is offset by said resistance in the ratioof the-weight of said string and the head of said liquid. Thus, a material part of the string weight is counterbalanced by 'the liquid head.

When the string is moved.- up, the piston 23 moves through low pressure; in interior 29 while its bottom face 24 is subject to the above-mentioned liquid head. Therefore, the string, above said piston, is counterbalanced, as before, bysaid head.

Thus, at all times, the weight of the string is, in part, counterbalanced and the stresses therein materially reduced. Whatever reduction of, stress in the string occurs is transmitted to tubing I I. Since said tubing is stationary, thesame is'better ableto absorb the stresses without break.- age than is the reciprocatingv string I8.

It will be realized from the foregoing that, the top of piston 23- is sealed off from the` liquid pressure and head in tubing II and operates in; an atmosphere that is vented to the well casing 5. Consequently, whether piston` 2-3` isY moving up or down or is at rest,` only thel under face 2d thereof is subjected to high pressure that hydraulically compensates for part of the string` weight.

It will be clear from the foregoing that piston;l 23, during its downward stroke acts in the. manner of a dash pot on the.- liquid displaced thereby; Said piston, therefore, serves to dampen anyv vibrations that may be set up in the long string: of sucker rods. Such dampening, by destroying or, at least, greatly minimizing vibration, preventsV build-up of harmonic vibrations that are a major: cause of metal fatigue.

While I have illustrated anddescribed' what I' the best mode of carrying out my invention, the construction is,v of course, subject to modification without departing from the spirit and scope of the' invention. It is, therefore, not desiredl to restrict the inven. tion to the particular form of construction il.- lustrated andl described, but to cover all modifications that may fall within the scope of theappended claims.

Having thus described the invention, what I claim and desire lto, be secured by Letters Patent 1s:

l. In a well having a length of tubing extending longitudinally therein anda pump,l in the lower end of said tubing to displace material from the bottom of the well upwardlyv through said tubing, a reciprocative string extending longitusure produced yby the pump.

The improvements according to claim 1:

said packing comprising at least two longiturial from the bottom of the Well upwardly through said tubing, a reciprocative string extending 1on- 20 interengaging should-ers, the head of the producto pressure lower than the pressure produced by the pump, and a by-pass in said tubing for the production of said pump around lthe `mentioned upward force that, in part,

counterbalances the Weight of the string.

References Cited in the file of this patent UNITED STATES PATENTS 0 Number Name Date Olson Aug. 2OJ 1895 Buvinger et a1. June 9, 1925 Standler May 2, 1933

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