US2953095A - Acoustic deep well pump with free compression column - Google Patents

Description

A. G. BODINE sept. zo, 1960 ACOUSTIC DEEP WELL PUMP WITH FREE COMPRESSION COLUMN 2 Sheets-Sheet 1 Filed Jan. 13, 1958 FIG.

INVENTOR. ALBERT G4 BODLNE 'l' l' l ATTORNEY A. G. BOBINE 2,953,095

ACOUSTIC DEEP WELL PUMP wm: FREE coMPREssIoN COLUMN Sept. 20, 1960 2 Sheets-Sheet 2 Filed Jan. 13, 1958 INVENTOR.

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ALBERT G. BODINE ATTORNEY ACOUSTIC DEEP WELL PUlVIP WITH FREE COMPRESSION COLUlVIN Albert G. Bodine, 12130 Moorpark St., Sherman Oaks, Calif:

Filed Jan. 13, 195s, ser. No. 708,601

s claims. (Cl. `s- 1) This invention relates generally to sonic deepl well pumps, of the general class disclosed inmy prior Patent No. 2,444,912, and deals especially with improvements in such pumps with particular reference to attaiment of greatly enhanced ability to withstand elastic fatigue.

The basic principle of-the sonic type well pump is the generation and transmission of longidutinal elastic waves, i.e., powerful sound waves, in a solid elastic column (pump tubing, rod, etc.), with the elastictvibrations of such column actuatingta fluid impelling means in the pump tubing. In many forms of the pump, this fluid impelling means includes or is associated-with a check valve. In the simplest form, as heretofore lknown, the sonic pump consists of an elastic column in the form of an elastic (eg. steel) string of pump tubing, one or more uid impelling means in the tubing, a wave generator mounted atop the tubing, whereby to deliver alternating force pulses to lthe tubing and thereby send `waves of elastic deformation down the same, and a support means suspending the pump tubing from itsupper end.`

A characteristic of all prior sonic pumps of the class described is that the elastic deformation waves are transmitted through an elastic column which -issuspended primarily in tension from the upper portion of the well, The elastic waves traveling along the column accordingly involve periodic increases and decreases in a tension which is in the column as a consequence of its weight and `its upper end support point. That is to say, there exists a tension bias in the column, zero at the lower end, and increasing to a large value at the ltop end where the column is supported. The wave action in the column therefore consists of periodic increases and decreases in this biasing tension. The column is thus always in tension, and experiences periodic increases and decreases in tension. Such an elastic column, with its couplings, hung in tension, and carrying periodic waves consisting of increases and decreases in tension, is subject to the threat of early fatigue and fatigue failure when very high sonic power is utilized. Careful attention to selection of materials and to the development of designs which avoid stress concentrations are required under such conditions in order to attain reasonable life prior rto ultimate fatigue failure.

The primary object of the present -invention is to provide a sonicpump of the class mentioned, but which avoids proneness to fatigue failure, and which therefore permits less attention Ito selection of materials, as well as to avoidance of stress concentrations.`

My present invention embraces several concepts, the

States Patent rst and foremost of which is to stand the elastic column in compression, with a support point within thelower end region thereof. Accordingly, for the principal part of the length of the column, the elastic Waves therein consist of alternating increases and decreases in compression, rather than tension. Since, as Vis known, periodic fluctuations incompression Vdo not lead to fatigue failure of elastic materials, that problem is eliminated for the extent of the column that isin compression. The elastic. waves transmitted down 4the column will, in general, create periodic tensions in the upper portion of the column, where the compression is sufficiently low that it can be exceeded on=the tension half-cycles of the wave. Also, any small length of the column below the lower end support point necessarily hangs in tension. For these limited extends of the column which still experience a tension cycle, carefully selected materials and careful design against stress concentrations are still requisite to a degree. But a very large fraction of the column has been removed from the possibility of fatigue failure, with accompanying possibility of great savings in initial cost, together withgreatly reduced'threat of fatigue failure, resulting shut down, and replacement cost.

As disclosed in my aforementioned prior patent it is possible, by adjustment of the frequency of the elastic wave transmitted down Ithetcolumn, to vcreate a standing wave along the column, with quarter-wave-spaced velocity nodes `and antinodes, Assuming that such an elastic column, with a longitudinal elastic standing wave active therein, were free in space, its upper and lower endsV would be antinodal regions, and one, or a number, of nodes would be found, along. the column. A further concept ofthe inventionis to provide a support point for such a column at or close to the lowermost node of the standing wave.

located at a node above they lowermost node, eg., at'

somenode above where the nodal denition is not so pronounced as it is at the lowermost node. Or it may simply be located at a selected point in the gradual transition region between a node and an antinode. Where greater wave energy extraction from the column is desired, the attachment point is moved toward an antinode; where less energy extractionis desired, the attachment point is moved toward a node, especially the lowermost node. Thus, precise selection of a desired energy eX- traction rate is feasible.

The invention will be better understood from the followingv detailed description of a presentillustrative embodiment thereof, references for this purpose being hady to accompanying drawings, in which:

lFigure 1 is a view of an illustrative embodiment of This lowermost node is locatedV one-quarter of a wavelength up from the bottom end ofV 3 a pumping system in accordance with the invention, the length of the installation being, of course, materially shortened for convenience of illustration;

'Figure 2 is a longitudinal sectional view of the upper end portion of the pumping system of Figure l;

'Figure 3 is a longitudinal sectional View of a portion of the tubing lower down, showing a tubing guide and centering device;

iFigure 3a is a transverse section taken on line 3a-3a of Figure 3;

Figure 4 is a longitudinal sectional View of ya portion of the tubing, showing a fluid impelling and check valve unit;

Figure 5 is a longitudinal sectional view of the lower portion of the pumping system, a portion being broken away; and k Figure 6 is a longitudinal sectional view of la modiied uid impelling unit.

In the drawings, numeral 10 designates generally a well bore, lined Vby casing 11, which extends down to theV region of the oil bearing formation 12.

Annularly spaced inside casing 11 is an elastic column, in'this case a pump string tubing 13, composed typically of 30-foot lengths or stands of steel or steel alloy tubing, joined by suitable couplings 14. A good grade of steel alloy is generally desirable, though, for reasons mentioned in the foregoing, the main length of the tubing is not subject to elastic fatigue, and these Vregions of the tubing string may be fabricated to less stringent specifications, as will be discussed more fully hereinafter.

The lower end of tubing string 13 carries a fluid impelling assembly 15, and there maybe additional such assemblies at selected points in the tubing above. It is often found desirable Vto use one such assembly at each tubing coupling. Y

The upper end of tubing string 13, above ground surface G, is joined by coupling 16 to the tubular part 17 mounting plate 23 on the upper end of a guidetubing 24 that extends down for a distance around tubingV 13.

The adapter 1-'9 rests on the upper face of plate 23, outside shoulder 22, and is formed with a peripheral flange 25 which is engaged and held downby means of a clamp ring 26 fastened to plate 23 as by screws 27. The flange 21 of fitting 18 will be seen to fit snugly inside the lower portion of the adapter 25, and the adapter has an internal downwardly-facing seat'28 which engages the upper side of ange 21,V all as clearly shown in the drawings.

Mounted on the top of adapter 19 is a vibration or Velastic wave generator unit generally designated by numeral 29, and which will be more fully described hereinafter. A casing head 30 is mounted on the upper end of casing 1'1, and has a hollow interior leading to ports 31, to which are coupled gas outlet pipes, not shown. A

Vtubular bearing housing 32 for guide tube 24 has near its lower extremity an external ring ange 33 secured to casing head 30 as by screws 34, and the housing portion 32a below flange 33 is received inside a casing head opening 35 and sealed therein as by ring seal 36.

Bearing housing 32 carries near its upper and lower ends suitable bearing bushings 37 and 38, respectively, adapted for sliding support of guide tube 24, and suitable seals are used above and below these bearings, as indicated at 39 and 40, respectively.

It will be seen that the bearing housing 32 is supported from` casing head 30, andk in turn from the casing 11 which is iirmly supported by the walls of the Well bore, but that the tubing string 13, Vguide tube 24,'mounting plate 23, and the adapter 19 and vibration generator 29 have nomeans of vertical support aboveV the ground surface, and on theV contrary,are Vfree forvertical sliding movement within the bearings 37 vand 38 carried by bear-y ing housing 32. The primary support place for these members is, as preliminarily described, in the lower end portion of the well, so that a large length of the tubing 13, i.e., from the support point to the top end, will stand in compression, as an elastic compression column.

Preferably, to prevent rotation of the tubing string 13, vibration generator 29, etc., relative to the casing, a pair of pivotally connected links 41 and 42 are pivotally connected at 41a and 42a, respectively, to the mounting plate 23, and to a bracket 42b on the bearing housing 32. These links permit verticalvibratory movement of the generator, tubing string 13 and guide tube 24, but hold said members against rotation.

A typical and preferred lower end support means for the tubing will next be described. At a selected point of the tubing string, in the lower end region thereof, in certain cases at a one-quarter wavelength distance from the bottom end of the tubing string, a special coupling 14a is used, provided with external threads engaged by a second coupling '44, into which is threaded the upper end of a support casing 45 which extends downwardly inside well casing 11 and outside tubing string 13, as shown. This support casing 45 extends downwardly beyond the lower end of tubing string 13, and to its lower end is coupled, as by coupling 46, a foot member 47, which is tubular and hollow down to and below uid intake ports 48 formed therein, and which is solid at the bottom and rests iirmly on the lower end of the well hole. The tubing string 13 is thus supported at coupling 14a, and stands in compression thereabove, while hanging in tension therebelow. Casing y45 stands in compression on the bottom of the well hole.

The lower end of tubing string 13, below lowermost check valve l15, carries, in the present illustrative embodiment, a rubber casing swab 49 which slidably engages the interior surface of casing 45.

While not an essential in a sonic type pump, I have here shown the use of a foot check valve assembly 50 in the casing 45, above uid intake ports 48.

The aforementioned vibration generator 29 may be of the same type as shown Yand described in my aforementioned Patent No. 2,444,912, and is hence shown in a somewhat diagrammatic fashion herein. Housing 65 contains oppositely rotating meshing spur gears 66 having shafts carrying eccentric weights 67 which balance out horizontal vibrations but which coact to produce a substantial alternating orV oscillatory force in a vertical direction. Any suitable driving means, not shown, may be provided for the generator. ForY example, one of the gear shafts may carry a universal joint driven by a drive shaft from a suitable prime mover, which may be an internal combustion engine or an electric motor.

The above-mentioned iiuid impelling assembly 15 cornprises -a cup 51 fsnugly received in the lower end portion of tubing string 13, and having in the lower portion thereof an annular seat 52 Mound an intake passage 53 formed vin a convergent intake member 54. A tubular fitting 55 screwed on to the lower extremity of tubing string 13 is reduced at 56 to `afford an upwardly facing annular shoulder 57, which engages the lower end of member '54, and a soft rubber sealing ring 58 around member 54 is compressed tightly by the member 54 and the lower extremity of tubing string I13 to eiect a suitable seal when the iitting 55 is screwed tightly onto tubing string 13. in the present illustrative embodiment, a check valve element is employed, in the form of a check valve disc 59 seating on the afore-mentioned annular seat 52, and in the operation of the pump, is limitedly movable between said seat and an interrupted lupper seat 60a at the lower ends of ribs k60 formed inside cup' 51. The disc 59 Iis of smaller diameter than the seat 52, so that when lifted above the seat, a tiuid passageway is formed from intake passage 53Y aroundthe periphery of the disc to the space between the ribs 60, and thence upwardly into the tubing string.V Y

Fitting 55 on the lower end of tubing string 13 has a reduced tubular downwardly extending portion 61, to which the hub portion of the aforementioned swab 50 is rmly attached.

As mentioned earlier, a fluid impelling assembly, similai to 15, is preferably used at the various tubing joints above, and these may be the same in general construction and operation as the described assembly 15. Such an assembly is shown at 15a in Figure 4, incorporated in a tubing coupling 14.

The check valve assembly 50 at the lower end of casing 45 may also be of similar construction. Thus it may comprise a cup member 62 seated in the lower portion of casing 45, and designed to afford upper and lower seats for a vertically movable check valve disc 63. The cup 62 has a convergent inlet portion 64, and a rubber sealing ring 65, which in this instance is compressed between the lower end of casing 45 and the upper end of member 47, when the latter is screwed into coupling sleeve 46.

Operation will first be described with the assumption that foot valve 50 is omitted. When the vibration generator 29 is driven, a vertically alternating or oscillating force is applied to the upper end of the elastic tubing string 13 through adapter 19, mounting plate 23 and fitting 18. It will be recalled that the tubing string 13, supported near its bottom, stands in compression from its lower end region point of support 14a to its top end, and additional compression is imposed by reason of carrying the vibration generator 29. The tubing therefore has a compression bias, which is of course greatest at the point of support, and least at the top end. Below the point of support 14a the tubing string is suspended in moderate tension. The alternating force applied to the upper end of the elastic tubing 13 by the generator 29 causes alternating sinusoidal pulses of compression and rarefaction in the tubing relative to its described compressive bias. These pulses cause yalternating elastic deformation waves, of compression and rarefaction, to be launched down the tubing. The waves so started down the tubing travel to the lower end thereof, and are reflected from the lower end to travel back up the tubing. Reaching the upper end, they are reflected back down, and so on. Assuming the case of a tubing length which is approximately equal to a whole number of half-wave lengths, at the generated wave frequency, the reflected and forwardly traveling waves interfere with and reinforce one another to produce a resonant standing Wave in the tubing. For one typical example, the pump tubing may have a length equal to a full wavelength )t for the generated wave frequency. A full wavelength standing wave can then be established (Fig. 1) with velocity antinodes V at the upper and lower ends of the tubing and at the midpoint, and with a velocity node N located a quarter-wavelength distance from each end. A support means for the tubing may then be used at the lower node, as described above, permitting a strong standing wave in the tubing. Other points of support permit standing wave action, modified in accordance with the particular support point chosen, and the wave frequency, as will be understood by those skilled in the acoustics art.

The several fluid impelling assemblies 15 and 15a in the pump tubing are caused to vibrate vertically as a result of the wave action in the tubing; and in cases of standing wave operation, those located at or near velocity antinodes (which is the preferred location) will of course vibrate with greater amplitude than those in the nodal regions.

The mechanism by which the fluid impelling assemblies 15 and 15a elevate well fluids through the pump tubing as a result of the vibratory Wave action has been fully set forth in my aforementioned Patent No. 2,444,912, and need not here be repeated in full detail. the downstroke of the vibratory motion of the tubing and Briefly, on Y assembly 15 or 15a, the acceleration becomes greater' than that of gravity, and therefore greater than that of the column of fluid in the tubing above. A suction, or void, is therefore developed in the column of liquid, above the assembly 15. Liquid below the assembly, displaced by the downward movement of the assembly, thus passes upwardly, past the check valve disc, into the void above, thus adding liquid to the internal liquid column above. On the upstroke, the check valve seats, and the column of liquid is elevated. It is not necessary that there be a denite check valve element, such as the disc 59. ln Figure 6, I have shown a modified fluid impelling assembly 15b, similar to 15a, excepting that no check valve disc such as 59 is used. A continuously open nozzle passage 64 through the assembly is defined by a convergent wall 65, having nearly parallel sides near its upper end, terminating in a final contraction such as indicated at 66. Owing to the shape of the nozzle, liquid forced upwardly therethrough on the upstroke exceeds that returning on the downstroke by a ratio of say two to one. This difference results from welleknown characteristics of flow through orifices and nozzles. The pump thus operates successfully notwithstanding some back ow on the downstroke, so long as the back ow does not equal the up ow on the upstroke.

Operation may be somewhat improved by use of the swab 49 on the lower end of the pump tubing string, in combination with the foo't check valve 50. On each vibratory downstroke of the pump tubing, the uid body between the swab and the check valve 50 is placed under compression, causing the check valve disc 63 of valve 50 to seat downwardly, and so maximizing the volume of uid forced upwardly past the check valve 15. On each upstroke of the vibratory pump tubing, a suction is developed between the swab and the valve 50, causing valve disc 63 to lift, and a quantity of well uid to enter.

In the operation of the pump, collection of gas in the fluid space below the check valve15 interferes with pumping. Gas in this region is accordingly bled upwardly into the space between tubing 13 and casing 45 through a port 75 in swab 49, and from the space between tubing 13 and casing 45 to the space between tubing 13 and casing 11 via a passageway 76 through coupling 14a.

As described previously, the elastic pump tubing stands in compression down to support coupling 14a, and hangs in tension therebelow. The compression bias is maximum at the support coupling and minimum at the top. Further, the alternating force applied to the upper end o'f the tubing creates traveling wave pulses of compression and rarefaction, which alternately add to and subtract from the compression bias. In the very uppermost region of the pump tubing, where the compressive bias is not large, the rarefaction pulses may exceed the compressive bias, thus placing this portion of the tubing under tension for a portion of each half cycle. A little lower down is a point at which the pulse of rarefaction just equals the compression bias, so that the tubing does not go into tension, but merely to a state of neutral stress. Below this last-mentioned po'int and down to the support coupling 14a, the rarefaction pulse is exceeded in magnitude by the compressive bias, so that the wave action consists entirely in alternating increases and decreases in compression. This favorable last-described condition prevails for the majority of the length of the tubing string. Throughout this length, liability to' fatigue failure owing to elastic wave action in the tubing and couplings is eliminated. Accordingly, this portion o'f the tubing and the included couplings may be fabricated of ordinary tubing and coupling materials, and without special care to avoid such stress concentrations as might, under tension, lead to early fatigue. The very upper portion of the tubing, as well as that portion hanging in tension below the support point, are still, of course, subject to the threat of elastic fatigue failure, and should continue to be made of good steel alloys and with good fatigue resisting design. The exact location down from the upper end of the tubing at ywhich the wave action in the tubing ceases passing Vthrough a partial tension half-cycle will of course vary in any lgiven pump installationwith the weight and force output of the wave generator.

One 'field installation of sonic pump in accordance with the drawings herein has a tubing length of V120() feet, and develops a full wave length standing wave at a wave frequency o'f 760 cycles per minute. The nodal point ysupport coupling for the tubing is located 300 feet up from the lower end. With deeper wells, the wave frequency will generally be adjusted to provide more than one wave length along the tubing. With the support point in such cases at a quarter-wavelength from the bottom, a substantially larger proportion o'f the tubing will stand in compression, and correspondingly increased benefits are realized from the practice of the invention.

As mentioned in the introductory paragraphs, in the event it should be desired toV extract vibration or wave energy from the tubing, the support coupling 14a may be displaced from thernode by a selected distance. Under such conditions, the tubing will undergo a degree t of vibration at the support point, and this vibration will be transmitted into thercoupling 14a, down the support casing 45, and tothe foot member 47, from which this energy is radiated into the formation, as for the purpose of increasing the rate of migration of well uids therethrough.V Y Y If it is desired to place a maximum length of the tubing string in compression, and `at the same time limit the amount of sonic energy extracted from the tubing, then, =l have found, it might be desirable to locate the support point close to the lower end, and use a compliant structure or material for support means 45.

As a consequence of the pump tubing standing u-nder considerable compression, particularly toward its lower end, the laws of column buckling must be considered. Any such Ibuckling tendencies can be combatted by using larger diameters ofrtubing toward the bottom, and/or fitting the tubing closely within a guide means. For example, as suggested in Figure 5, a guide tubing 80 may be coupled onto the support coupling 14a,.and extend upwardly a distance as necessary to guard against buckling. lt may be centered in the casing in any desired fashion, not shown. Also, tubing guides such as 81 (see Figure 3) may be mou-nted directly on the tubing 13 at spaced points. These guides 81 may comprise aV rubber `sleeve 82 fitted onto the tubing and furnished with longitudinal ribs 83 which .carry a fabric impregnated phenolic ring 84 adapted to engage the inside surface of the casing l1. Such a guide does not have a tendency to wear the casing, and serves to center the tubing and to guard against buckling. The friction introduced by these guides rubbing on the casing is negligible, particularly if a small flow of output uid is introduced at the top of the casing Aannulus.

The drawings and description show one present illustrative embodiment of the invention. It will be understood that various changes in design, structure and arrangement may be made without departing from the spirit and scope of the broader of the appended claims.

l claim: Y

1. YIn a deep well sonic pump, the combination of: an elastic pump tubing in the well bore, a sonic wave generator coupled to said elastic pump tubing for maintaining therein periodic longitudinal deformation waves of compression and rarefaction relative to normal mean longitudinal stress-at any given point therealong, fluid impelling means in said tubing reciprocated by said waves in said tubing, and tubing support means for supporting said tubing atta support point within the lower region of said tubing but spaced substantially above the lower; extremity thereof, said means including la coupling fixed to/ said tubingmat said support point, and a leg fixed to Vsaid coupling `and extending downwardly pastrth'e lower end of the tubing and including a footing at its lower end in supporting engagement with the lower end of the well bore, in such manner that the weight of said tubing is borne by said support means, and said tubing stands normally in compression above said support point, and hangs normally in tension below said support point.

2. The subject matter of claim l, wherein said leg of said tubing support means comprises a support casing positioned within the well bore outside the tubing and coupled at its upper end to said tubing coupling.

3. VIn a deep well sonic pump, the combination of: an oscillating uid impelling `member adapted for 'placement in the lower region of the well bore, an elastic column of solid material in the well bore extending from the ground surface to said uid impelling member and operatively coupled to the latter, a sonic wave generator coupled to said elastic column for maintaining therein periodic elastic deformation waves of compression and rarefaction relative to normal Vmean longitudinal stress at any given point therealong, and column support means for supporting said column at a support point within the lower region of said column but spaced substantially above the lower extremity thereof, said means including a coupling xed to said column at said support point, and a leg xed to said coupling and extending downwardly past the lower end of the column and including a footing at its lower end in supporting engagement with the lower end of the well bore, in such manner that the weight of said column is borne by said support means, and said column stands normally in compression above said support point, and hangs normally in tension below said support point. Y v Y 4. In a deep well sonic pump, the combination of: an elastic pump tubing in the well bore, a sonic wave generator coupled to said elastic pump tubing for maintaining therein periodic longitudinal deformation waves of compression and rarefaction relative to normal mean longitudinal stress at any given point therealong, said generator being Yoperable at a frequency to establish a standing wave in said tubing, with a nodal region in the lower portion of the tubing, above the lower end thereof, fluid impelling means in said tubing reciprocated by said waves in said tubing, and tubing support means for supporting said tubing at said nodal region, said means including a coupling iixed'to said tubing at said support point, and a leg fixed to said coupling and extending downwardly past the lower end of the tubing and including a footing at its lower end in supporting engagement with the lower end of the Well bore, in such manner that the weight of said tubing is borne by said support means, and said tubing stands normally in compression above said support point, and hangs normally in tension below said support point.

5. In a deep Vwell sonic pump, the combination of: an oscillating uid impelling member adapted for placement in the lower region of the well bore, an elastic column of solid material in the well bore extending from the ground surface to said fluid impelling member and operatively coupled to the latter, a sonic wave generator coupled to said elastic column for maintaining therein periodic elastic deformation waves of compression and rarefaction relative to normal mean longitudinal stress at any given point therealong, said generator being operable at a frequency to establish a standing wave in said column, with a nodal region in the lower portion of the column, above the lower end thereof, and column support means for supporting said column at a support point in proximity to said'nodal region, said meansl including a coupling fixed to said column at said support point,Y and a leg fixed to said coupling and extending downwardly past the lower end of the column and including a'footing at its lower end in supporting engagementY with the lower end of the well bore, in such manner that Vthe weight of said Qlumn is borne by said support means, and said column stands normally in compression above said sup- 2,680,485 Bodne June 8, 1954 port point, and hangs normally in tension below said sup- 2,699,723 Ecker I an. 18, 1955 P0 Pfmt- FOREIGN PATENTS References Cited in the le of this patent 5 20,264 Germany Dec. 16, 1882 UNITED STATES PATENTS 816,054 Germany OC- 81 1951 562,285 Delpeyrou et a1 June 16, 1896 OTHER REFERENCES 991,708 Fasting May 9, 1911 University Physics, Sears and Zemansky, published 1,580,479 Frankeneld Apr. 13, 1926 by Addison-Wesley (Reading, Mass), 1956, pages 368- 2,444,912 Bodine July 13, 1948 382 relied on. (Copy in Scientific Library.)

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