US3255699A

US3255699A - System for pumping from sandy wells with sonic pump

Info

Publication number: US3255699A
Application number: US353205A
Authority: US
Inventors: Jr Albert G Bodine
Original assignee: Individual
Current assignee: Individual
Priority date: 1964-03-19
Filing date: 1964-03-19
Publication date: 1966-06-14
Anticipated expiration: 1983-06-14

Description

June 14, 1966 A. G. BOBINE, JR

SYSTEM FOR PUMPING FROM SANDY WELLS WITH SONIC PUMP 5 Sheets-Sheet 1 Filed March i9. 1964 June 14, 1966 A. G. BOBINE, JR

SYSTEM FOR PUMPING FROM SANDY WELLS WITH SONIC PUMP 3 Sheets-Sheet 2 Filed March i9, 1964 June 14, 1966 A. G, BoDlNE, JR

SYSTEM FOR PUMPING FROM SANDY WELLS WITH SONIC PUMP Filed March 19, 1964 5 Sheets-Sheet 5 W E M United States Patent O 3,255,699 SYSTEM FOR PUMPING FROM SANDY WELLS WITH SONIC PUMP Albert G. Bodine, Jr., 7&77 Woodley Ave., Los Angeles, Calif. Filed Mar. 19, 1964, Ser. No. 353,205 Claims. (Cl. 10S-1) This application is a continuation-impart of my prior application Serial No. 223,026, `filed September 12, 1962, now Patent Number 3,127,842.

This invention relates generally to deep well sonic pumps, of the type disclosed in my US. Patent No. 2,444,912, and more particularly to systems for improving the ability of such pumps to pump wells in especially sandy formations and whose production fluid sometimes suddenly carries a large proportion of sand.

In my said prior Patent No. 2,444,912, I disclosed a type of deep well pump oper-ated by periodic deformation waves of tension and compression generated by means of a sonic vibration generator at the ground surface and transmitted in a longitudinal direction through an elastic steel column, usually the pump tubin-g, to certain fluid impelling and check valve means mounted along the column. In the usual case of the column -being the pump tubing, these fluid impelling and check valve means are mounted within the tubing. The periodic deformation waves are generated at sufficient frequency to provide longitudinal -waves in the tubing having a quarter wavelength which is no longer than substantially the length of the tubing. Usually, for deep wells, the tubin-g len-gth is many times the quarter wavelength of the wave generated in the tubing. In this action, the pump tubing is not bodily reciprocated, but waves of elastic longitudinal deformation travel along the tubing, causing local regions of the tubing to be set into vertical oscillation. The frequency at which these w-aves are generated may be, for example, 20 cycles per second, and they are generated with sufcient intensity to give a maximum deformation stroke in the tubing of the order of say 1/2". In some cases, it is of adva-ntage to adjust the frequency of operation so as to establish -a longitudinal standing Wave in the pump tubing, with nodes or pseudonodes, andantinodes spaced by quarter-wavelength distances along the tubing. In such cases, the uid impelling and check valve means mentioned above are sometimes located as near as possible to the antinodes. For -a complete description of the operation of such a sonic pumping system, reference is directed to my aforesaid Patent No. 2,444,912.

The Iwell fluids from some wells carry a large sand content, and the greater this sand content, the more difcult is the well to pump. A proportion of the sand reaching the well bore comes out of suspension in the well uids, and chokes the Well. Many wells having good potential for petroleum production .are nevertheless so sandly that they cannot be successfully pumped, and now stand abandoned. Sonic type pumps can often produce from very sandy Wells, but the production fluid carries so much sand from the formation that problems of subsidence can then arise. The pump disclosed in my parent application Serial No. 223,026 facilitates a new pumping practice which permits successful production from many sandy wells. Some especially sandy well tend to suddenly heave from time to time, involving often considerable cave-in of sand into the .bottom of the well, sometimes chocking it completely. This condition can even choke a well having the improvements disclosed in my application Serial No. 223,026.

The general object of the present invention is the provision of a sonic pumping system capable of successful pumping of especially sandy wells, and particularly sandy wells that tend to heave The pumping system of the present invention has the operational `features and advantages of that disclosed in my aforesaid `application Serial No. 223,026. Thus, it involves the concept of a recirculation of a quantity of de-sanded -well Huid back down the well via the annulus around the production tubing, and a combination of this recirculated diuid with the rising production column. Also, the sonic .wave action in the pump tubing, i.e., elastic deformation waves of compression and tension, produce sonic iields in the liquid column within the tubing, and in the well iiuid streams flowing through the formation to the well bore. The sonic eld within the iluid column in the tubing can be quite intensive, and sets up an agitation which tends, under the conditions of relatively high iiuid column velocity produced in accordance with the invention, to keep the sand in suspension in the luid. The sonic energy bled from the tubing and transmitted back through the fluid streams leading to the 'well bore is not, without special wavev radiating formations, of a high order of magnitude, .but is still suicient to affect the sand-carrying characteristics of those streams. ln particular, when the ow velocities of these streams are low, the sonic -eld actually tends to cause the sand to drop out of suspension.

These two advantageous conditions, i.e., sand dropping out of suspension in the fluid streams leading to the well bore, and sand staying in suspension in the Well uids rising in the production tubing, are a characteristic of the pump of the invention. The first of these conditions mean, of course, reduction in ythe quantity of sand carried out of the formation, and corresponding. reduction of the sand problem within the well bore and the pump tubing, as well as reduction in the problem of land subsistence owing to the opening up of cavities :by pumping of sand therefrom. The second condition, retention of sand in suspension in the rising production column, is of obvious benefit. The invention achieves both of these :benets by the procedure mentioned brieiiy above, namely, the recirculation down the well, via the annulus around the production tubing, or alternatively, via any outer annulus or any conduit placed insaid annulus, of a good ow of desanded well duid, and the combining of the recirculated well fluid with the well fluid freshly entering the production tubing from without. 1t will be seen that the recirculated Well fluid When combined (with the iluid already rising in the production tubing results in an increased flow velocity up the production tubing; and this increased flow velocity, with the added influence of the sonic field in the production column, results in maintenance ofthe sand in suspension, so that what .sand does enter the well bore with the well fluids and in the region of the lower open end of the production tubing is pumped up the latter, and delivered from the well. The tendency for a well to sand up is thus effectively combatted.

The'pump of the invention has, in addition to these features, a means for safeguarding against choking by heaving, or cave-in of surrounding sand, such as can sometimes iill into the annulus surrounding the pump tubing from below, even to the extent of blocking the liquid ow being sent down the annulus.

The invention involves certain additionalfeatures and advantages, as will be described in the following detailed description, with reference to the accompanying drawings, in which:

FIG. 1 is a longitudinal section view, with portions broken away, of a sonic pump equipped with the improvements of the invention, installed in a somewhat diagrammatically illustrated well;

FIG. 2 is a vertical detail section taken on line 2 2 of FIG. l.

FIG. 3 is a transverse section taken on line 3-3 of FIG. 2;

FIG. 4 is an enlarged view of a portion of FIG. 1, showing the valve on the lower end of the pump tubing in longitudinal medial section;

FIG. 5 shows, to still larger scale, a modification of FIG. 4;

FIG. 6 is a view similar to FIG. 5 but showing another modification;

FIG. 7 is a view somewhat similar to FIG. 1, but showing certain further modifications;

FIG. 8 is an enlarged detail taken from FIG. 7; and

FIG. 9 is an enlarged detail, to a somewhat smaller scale than FIG. 8, of `a further modification, which may be used with either the pumping system of FIG. l, or that of FIG. 7.

Referring first to the embodiment of the invention shown in FIGS. 1 to 4, a well ibore W is shown to be lined down through the earthen structure 8 and into sandy production region structure 9 by well casing 10, while annularly spaced inside casing 10 is a return fiow jacket 11, jacketed within which is the steel sonic pump tubing string 12, which functions not only as a production conduit to deliver the well uids from the ground, but `also as an elastic column adapted for transmission of elastic deformation vibrations, typically alternating waves of elastic compression and tension. It is prefcrable that the sonic pump tubing 12 is not a close sliding fit within jacket pipe 11, but is rather a loose fit, including the collars, so as to provide a .substantial annular clearance. Mounted at the top of casing 10 and jacket pipe 11 is a suitable casing head C; and the pump tubing or tubing string 12 extends upwardly through ysaid casing head, being packed or sealed Where it leaves the casing head by stuffing box 13. Tubing 12 has mounted on its upper end an elastic wave or vibration generator G. This generator G is sho-wn in a simple form embodying a housing 16 containing a device for vibrating the upper end of the tubing in -a direction longitudinally of the latter, thereby exerting a vertical oscillating force upon the upper end of the tubing.

The means for generating the vibratory action is here shown Iof a simple type embodying an eccentrically weighted rotor 17 turning on a horizontal axis in bearings supported within housing 16, and driven through driveshaft 18 from any suitable prime mover, such as an electric motor, not shown. Generator housing 16 is mounted on the top end of pump tubing 12 through an intermediate fitting 20, which comprises a bottom platform part 21 screwthreadedly receiving the upper end of the pump tubing, an annular neck part 22 bored as vat 22a to receive production fiuid from tubing 12, and an upper platform portion 23 which supports the generator housing and 1to which the latter is fixed by any suitable fastening means, not shown.

The vibration generator G and fitting are mounted on casing head C through a spring supporting device generally designated at 25 and comprising a plurality of coil compression springs 26 acting between casing head C and platform 21, together with vertical guide rods 27 for said springs mounted on top of the casing head `and extending slidably through guide apertures in the platform 21, as clearly represented in FIG. l.

The production fluid delivery pipe line 30, including a flexible hose section 32a, is coupled into fitting 20 so as to communicate with the bore 22a therein, and thus with production tubing 12; and this delivery line 30 is shown, diagrammatically, as delivering to a sand trap 32, to be presently described more particularly.

A pipeline 34, conducting de-s-anded production liquid from sand trap 32, couples into casing head C so as to communicate with a passage 35 leading to the annulus 36 between the exterior of pump tubing 12 and the interior ofjacket pipe 11.

Referring further `to sand trap 32, the latter comprises a tank 36 having therein a transverse partition 37 forming a sand settlement compartment 38 and a compartment 39 for relatively cleaned well fiuid which has passed over the upper edge of partition 37. Tank 36 has an outlet pipe 40 serving to deliver cleaned production fluid from the well installation, and another outlet pipe 41 serving to return a regulated flow of well liquid back to the well. The dot-dash line 42 represents a pipeline connecting outlet pipe 41 with the aforementioned pipe 34 coupled into cas-ing hea-d C and communicating with the jacket pipe annulus 36. This pipe line 42 is shown to contain a control valve V by which the fiow of fiuid to annulus 36 may be regulated as required. A branch pipe line 44, shown to lead from pipe line 42, and which may contain a control valve V', optionally conducts liquid from the de-sander 32 to an inlet passage 45 in casing head C communicating with the well annulus 46 between jacket pipe 11 and well casing 10.

As disclosed in my aforementioned Patent No. 2,444,912 on sonic pumps, the pump tubing string 12 contains one or more fiuid impelling units, illustratively in the form of check valves such as indicated at 50, and the lowermost. of which is on the lower extremity of the pump tubing. A typical check valve 50 is shown in FIG. 2, and it will be understood that a suitable number of such check valves may be employed. Such a valve is located at and positioned by a conventional coupling collar such as commonly used to join adjacent lengths of pump tubing to form the complete tubing string. Thus, a coupling collar 52 screwthreadedly joins the upset end portions 53 on the adjacent ends of two lengths of pipe. A generally tubular valve body 54 is positioned within tubing collar 52 and within the upset end portions of the adjacent lengths of tubing 12. Valve body 54 is recessed on the outside to accommodate rubber rings 55 which are compressed when the coupling is made, in an obvious fashion, to position the valve body. The valve body has `a central bore 5S, which slidably receives a tubular stem 59 formed with a central longitudinal bore 60 to receive a long bolt 60 which clamps ripper and lower rubber valve-heads or

disks

61 and 62, respectively, against the corresponding ends of the stem 59. Longitudinal passageways 64 are formed through valve body 54, opening into the lower end of the valve body outside rubber head 62, and opening at the top inside the rubber head 61. The conical upper surface 65 of the valve body through which opens the passageways 64 is, as here shown, formed on an angle which conforms to the angular lower surface of the rubber disk 61, and the latter, in moving onto and off of surface 65, acts as a valve. Surface 65 acts as the coacting valve seat. It will be seen that the length of stem 59 is such as to permit the rubber' valve head 61 to seat against valve seat 65, so as to close off passageways 64, or to be elevated sufiiciently to open good flow passages from passageways 64 around the outer periphery of the valve element 61 to the tubing above.

The use of rubber for valve element 61, andespecially with a plastic for valve seat 64, gives an impelling element which is especially effective for applying kinetic energy to the fluid stream, and also to resist abrasion from the pumped sand.

The lowermost valve 50, as seen best in FIG. 4, is of similar construction to that illustrated in FIG. 2 and described immediately above, the only difference being that the coupling collar 52 in the case of the lowermost valve 5G differs from the coupling collar 52 of the check valves above in being provided at the bottom with an inwardly formed shoulder 68 which engages and supports the underside of the valve body 54. The intake 69 to the pump tubing will be seen to be through the shoulder 68. The operation of the check valves will be described presently.

The jacket pipe 11 will be understood to comprise a number of pipe sections, connected to one another by coupling collars such as indicated at 70. This pipe fits relatively loosely around the coupling collars S2 and 52', and relatively loosely also around optional bearing bushings 72 preferably mounted on the sections of pump tubing 12 at convenient intervals. Each such bushing 72 may be comprised of a molded, fiber-lled phenolic resin, or any other found suitable. Such a bearing or bearing annulus aids in generally centering the tubing within the jacket pipe lll, and is of low friction against the interior surface of the pipe lll, particularly when lubricated by petroleum liquids. The clearance space between the bushings 72 and the jacket pipe 1li, as well as between the

coupling collars

52 and 52 and the pipe 11, is large enough to permit imposition of a good hydrostatic head at the bottom of annulus 36, i.e., without so much constriction as to create undue frictional opposition to flow in the clearance regions indicated. At the same time, these clearance regions are preferably somewhat restricted, so as to tend towards prevention of upflow of sand into the annulus 36 under any conditions of undue sand choking during service.

A feature of primary importance in the invention is the use at the lower end of the tubing string of a well-fluidintake section 1li of jacket pipe 11which is closed at the bottom, as here shown, by a bull end 74, so as to completely surround or cage the lower end of the tubing string. This jacket pipe section lll extends preferably only for relatively short distance below the lowermost check valve, and is furnished below the lowermost check valve with flow-restricted well fluid intake means, typically and preferably perforations such as indicated at 75.

In FIG. 1, the producing formation is designated at 9, and, as explained, is of a sandy nature, easily capable of heaving,. or caving. Outside the sloping lines 78, and below the line 79, the sandy formation remains consoli dated or stable, while inside said lines, as at titl, there may be a quantity of loose and active sand. This loose sand at 80 may be owing to 4having been carried in suspension by well fluids migrating toward the well bore, and/ or to socalled heaving, or caving of the well walls. The perforated jacket pipe lll', with its closed lower end 74, will be seen to exclude the larger part of such a sand fall from suddenly getting inside and choking, or literally burying, the intake 69 to the pump tubing la. It will be further observed that the perforations 75 are confined to the region below the lowermost coupling collar 52a, so that well fluids and sand are not admitted to the annulus 36 thereabove. Well fluids do migrate to and enter the perforations 75; and owing to the bull end 74 on the pipe 11', in-flow sand is retarded or limited from suddenly entering into the clearance space between coupling member 52 and the pipe ll', and into the pump intake 69, in such rapid volume as to choke these flow spaces.

FIG. 1 shows also the preferred use of engageable

splined elements

81 and 82, on the jacket pipe and vibratory pump tubing, respectively, to prevent accidental unscrewing of the latter in service.

The operation of the pump will next be described, and it will rst be assumed that operation is proceeding normally, with considerable sand. reaching the well bore with the well fluids, and entering through the perforations 75, but without large heaving such as tends to bury and choke the pump as described above. The well liquid will thus reach and enter the pump intake 69, and may normally tend to stand in pipe 12 at a levelabove lowermost valve Si?. Periodic elastic deformation waves of tension and compression travel down the pump tubing string 12 as a result of thel vertical alternating or oscillating force applied to the upper end thereof by the sonic generator device G. These elastic waves set local portions of the tubing l2 into vertical elastic oscillation through an amplitude up to say 1/2". The tubular valve members 54 carried by the tubing accordingly have this vertical oscillation. On each downstroke, the member 54 travels with an acceleration the valve element 61, and fluid displaced by the member 54 travels upwardly through the passages 64 therein and past the then unseated valve element 6l. On the upstroke, the valve element 61 seats, and the column of well fluid thereabove is dynamically accelerated in the upward direction. The column of well fluid above valve element 61 does not drop substantially during the downstroke of the member 54, because the acceleration of the latter considerably exceeds the acceleration of gravity. Fluid from the well entering into the tubing 12 is thus pumped up the production tubing 12, and delivered by a line 30 to sand trap 32.

The immediately foregoing description of operation applies to the sonic pump, in absence of any features of the present invention. The recirculation process, as first disclosed in my parent application Serial No. 223,026,A is preferably practiced by causing well fluid, such as that which has been desanded in trap 32, to flow via line 42, at a rate controlled by valve V, into and down the annulus 36 between the jacket pipe 11 and the pump tubing. At the bottom, i.e., below the collar 52 on the lower end of the pump tubing, this fluid reverses direction and enters the lower end of the pump tubing via the intake 69, as represented by the arrow r. It there combines with well fluids which have entered via the perforations in the jacket member 11, as represented by the arrow s. The combined flow rises in the pump tubing under the sonic pumping effect developed as described hereinabove.

lt will be evident that the combined flow of entering well fluid, i.e., flow directly from the formation, and recirculation flow, will tend toward maximization of flow velocity up the pump tubing. This increased flow velocity, together with the reduction in the proportion of sand content owing to addition of a proportion of de-sanded liquid, tends to keep the sand in the combined fluids iu the pump column from dropping out of suspension, and the elastic sonic wave activity within the rising production column, owing to the sonic wave action of the pump tubing, helps keep the sand in suspension by distributing it more uniformly in the fluids and by keeping it sonically agitated. Sand carried to the well bore by the well fluids is thus satisfactorily pumped up the production column. It will be noted that the recirculation fluid must be supplied at a rate such that the rate of upward flow of the combined fluids in the production tubing is above the rate at which a material quantity of sand drops out of suspension under the conditions of sonic wave transmission and vibration maintained in the tubing.

It will be seen that the addition of the recirculation flow up the pump tubing will in general reduce theproportion of flow up the tubing of well fluids which are arriving directly from the surrounding forma-tion. The velocities of the fluid streams from the formation to vthe well bore are correspondingly reduced, and loose sand is not so readily picked up and carried along to the pump by these streams. Moreover, as explained hereinbefore, the sonically vibratory pump tubing leaks sonic wave energy into these streams of well fluids coming from far back in the formation, and the effect of the steady sonic wave transmission back along the very low velocity streams is to cause sand carried thereby to drop out of suspension, so that a reduced quantity of sand is transported to the well. In addition, it is noted that fluid flow with the sonic pump is much more steady, Y

thus causing less pulsing shocks to the well formation than does a conventional plunger pump.

In the operation of the sonic pump, the valve V is used to control the rate of recirculation fluid in the production column. It will be evident that this proportion will vary with different wells and with different sand contents in the natural production fluid. The valve V is set so as to provide a recirculation flow rate which is found, on test, to establish adequate production from the formation, with sand content regulated to the level deemed or determined best for the case at hand.

.It will be seen that the rate of fluid flow directed down the vannulus is such that the flow rate of the combined fluids up the pump tubing exceeds the flow rate, or velocity, at which sand drops out of suspension.

Assume now the occurrence of sand heaving, or cavein. Loose sand may then ll in the region 80, either as indicated, or all around the pipe 11. Some sand will inevitably enter through the perforations 75, but, owing to the sand-flow-impeding barrier constituted by the pipe 11 ywith its bull end 74, there is ordinarily little likelihood of this sand filling in rapidly and high enough to fully bury the pump intake 69, or even to choke the annulus clearance space between the coupling element 52 and the inside surface of jacket pipe 11', such that even the recirculation liquid is prevented from reaching the pump intake. Under these extra sanded conditions, the pump can operate on whatever well fluid can reach the tubing intake through the caved-in sand, the perforations 75, and whatever sand does enter the perforations 75. The recirculation liquid can at this time be increased in flow rate by opening valve V, Suthcient 11p-flow velocity may thereby be regained to gradually pick up and pump the sand up the tubing 12. The important point is that the safeguarding features described prevent the pump from going completely out of operation, and permit it to gradually clear itself of sand, and thereafter resume normal pumping, aided by controlled recirculation flow, if desired, as in my parent application Serial No. 223,026.

A further feature capable of advantageous use under conditions of cave-in or large sand accumulation around the pipe 11' is the opening of valve V to re-circulate well iiuid down the well annulus 46, between the casing 10 and the jacket pipe 11, thence through the sand at 80, thence inwardly through perforations 75, and thence upwards through whatever sand stands in the bottom of jacket pipe 11', to the pump intake 69. By establishing a good flow along this path, sand around the pipe 11 can be gradually carried into pipe 11 and then elevated through pump tubing 12 to clear out the sanded condition. In this connection, the vibratory action of the lowermost end portion of the pump tubing, or the lowermost coupling collar thereon, radiates sonic waves outwardly through the well fluids and sand, and out .through the perforations 75. Thereby is produced a condition of general sonic agitation in the region about the perforated jacket pipe 11. With recirculation iiow from annulus 46 into perforated pipe 11 established at good flow velocity, and this condition of sonic agitation prevalent, the loose sand is better picked up by the iluids flowing into the perforations 75 and on up the pump tubing. Clean out of the caved in or accumulated sand is thus facilitated.

FIG. is a view showing a modification of a portion of the system of FIGS. 1-4. Components corresponding closely to those of FIGS. l to -4 are identified by the same reference numerals, but wit-h suffix a added in the case of FIG. 5. With this understanding, a jacket pipe is represented at 11a, and is coupled by a coupling collar 90 to a relatively short, perforated lower end jacket pipe member 91 having bull end 92. A vibratory pump tubing 12a is contained inside jacket pipe 11a, and the upset lower end portion of such tubing is indicated at 53a, coupled by coupling collar 52a to a similarly upset portion 92 on the upper end of a pump tubing member 93 which extends downwardly into the interior region of the coupling collar 90. A uid propelling and check valve unit 50a of the same type as the unit 50 of FIGS. l to 4, is confined and operates within coupling collar 52a.

A spacer ring 95 shouldered upwardly inside coupling collar 90 engages a shoulder 96 on the upper side of the collar portion 97 of a flexible rubber packer generally designated at 98, the lower end of said packer collar being engaged and confined by the upper end of bull end pipe member 91. The packer member 93 has a fiexible lip portion 99 which slidingly engages the outside of tubing 93, in the manner clearly shown in FIG. 5. Above the sliding and sealing engagement between packer or gland 98 and tubing member 93, there are formed in the pump tubing string certain ports for recirculation well fluid that has been sent down the annulus 36a. Thus, as here shown, there are such inlet ports 1G() in tubing 93, inlet ports 101 in the upset portion 53a of tubing 12a, just above lowermost valve 50a, and additional ports 102 in the tubing string 12a above. The recirculation fluid thus, in this case, enters the production stream at 10), 101 and at 102, or at any one or more of such ports. The sliding packer or gland 98 holds up an `annular column of liquid in the annulus 36a for some appreciable vertical distance, so that such column, by reason of its pressure head, serves as a good deterrent to sand working up between the pipe 93 and the jacket pipe 11a when the well suddenly, or on occasion, heaves a quantity of sand.

The packer 98 may be designed with such a degree of flexibility as to permit some downflow of recirculation liquid to the region below the pipe 93 when the fluid in the annulus 36a has risen to a sufficient height, and this recirculation fluid thus reaching down to a level below the lower end of the pipe 93 can under such conditions aid in picking up sand which has entered into the pipe 91. When there is insufficient pressure head for the recirculation iluid to pass the packer 98, it enters exclusively at 169, 101 and/or 102, as earlier described. At all times, the pressure head in the annulus 36a and the seal or restriction formed between the packer and the tubing 93 is effective to effectively oppose upflow of sand into the annulus 36a under any extremes of sand heaving'or cave-in. In the event of an extreme condtion of this kind, the Sand inflow is effectively stopped at the packer, and the recirculation flow through annulus 36a and in through the apertures such as 'and 101 can then act to gradually clear the sand out of the interior of the pipe 91, particularly in cases where such sand may have entered partially into the tubing 93, or even up into .the valve 50a. In such cases, of course, it is frequently desirable to send a considerable liow of recirculation fluid down the annulus 36a.

In FIG. 6, I have shown another modiication of the system of FIGS. 1-4, involving side opening check valves located in the pump tubing between two successive fluid impelling and check valve units 50b, for example, -the two lower such units, each of which corresponds generally to the units 50 of the embodiment of FIGS. l to 4. In the case of FIG. 6, compounds corresponding to those of the embodiments of FIGS. 1 to 4 and 5 identified by like reference numerals, but with the suf-'tix b added. Thus, pump tubing 12b shown to contain two spaced fluid impelling and check valve units 50b, and it will be understood that additional such check valve units may be spaced 4throughout the length of the tubing 12b, in accordance with teachings contained in my aforementioned sonic pump Patent No. 2,444,912. The uid impelling and check valve units 50b both in -structural makeup and in operation, are like the units 50 and need not be redescribed in detail. The tubing coupling collars 52b which screwthreadedly join adjacent end portions of tubing sections 12b resemble the collars 52 of FIGS. 1 to 4, but are lengthened in their lower portions and are additionally provided with side opening check valve units 110, adapted to periodically take in recirculation well liuid from the annulus 36b between the tubing column and the jacket pipe, here designated by reference numeral 11b.

The lowermost jacket coupling collar 90b resembles coupling collar 90 of FIG. 5, and it contains and mounts a packer 93h which is like the packer 98 of FIG.. 5, and which slidingly and sealingly engages a lowermost tubing section 93h screwed into the lowermost tubing coupling collar 52h. FIG. 6 shows fragmentarily a lower jacket pipe member 91b, which will be understood to optionally correspond to the bull end, perforated jacket pipe 91 of FIG. 5.

Returning to a consideration of the side opening check valve accommodated within the coupling collar B2b, the latter will be seen to be formed, below its internally 9 screwthreaded lower end portion 116 and the lower end portion of the valve Stlb accommodated therewithin, with a transverse partition 117, formed with well fluid circulation holes 118. Fastened to the underside of this partition 117, as by bolt 119, is a check valve retainer disk 121 having in its periphery concave seat-s for check valve balls 122 which are adapted to open and close lateral valve ports 123 formed in the side wall of collar B2b, just below partition 117. These check valve balls 122 move onto and off of their annular seats 124 around ports 123 in response to development of successive pressure and suction pulses in the region of the interior of the coupling collar 52h, below the upper valve member 56h.

It will be understood that, as in the case of FIGS. 1 to 4, recirculation well iluid is sent down the annulus 36h. rl`his -tends to be held by the packer at 85, so that an annular col-umn of such liquid rises in the annulus 36h. It is of course necessary that the side opening check valve units 110 be at a lower level than the level of the recirculation uid column in the annulus Seb, so as to be functionally submerged at the intake ends l of the valve ports 123.

In the operation of the sonic pump, the check valve elements 61b periodically move onto and off of the valve seats 65h, in the manner described in connection with region wherein a given check valve unit 50h is located,

the valve member 541: rises relative to the check valve element 61h, and the latter closes, creating a momentary suction therebelow, in the region of the side opening check valve unit 1111. The balls 122 accordingly are drawn off their seats 124, and recirculation liquid from well annulus 36h is drawn in through ports 123 and added to the well uid column within the pump tubing. On each downstro-ke, on the other hand, `a positive pressure pulse is created, by downward acceler-ation of body 54h, in the interior region vof the coupling collar adjacent the valve balls 122, causing these balls to move onto their seats 124, and thus prevent outflow of well iiuids through the ports 123. Accordingly, recirculation iiuid is taken in from well annulus 36h into the production tubing 12b and added to the iluid stream rising therein on each upward movement of the tubing coupling collar 52h equipped with a side opening intake check valve 110.

The system'modiiied as indicated in FIG. 6 thus affords an isolated flowpath for downwardly owing recirculation well fluid going down the annulus 36h between the tubing string `and the jacket pipe, then inwardly in to the tubing string and upwardly with the production column well fluid. This o-w will be seen to be isolated from the d well conditions below the tubing string by the packer 98h. The recirculation flow in this instance aids the upow of sand by adding extra uid volume and therefore higher upow velocity, over yand above that produced by the well pump itself. At the same time, there is avoided the sometimes undesirable commingling of the introduced recirculation fluid-with the well uid-s in the well. Avoidance or minimization of such commingling permits the use of a foreign recirculation fluid such as water, which might not be desirably allowed in contact with the well formation. Moreover, thev system of FIG. 6 avoids imposition of the fluid column pressure in the well annulus 36h from being imposed upon and creating excessive pressure effect against the oil producing formation.

FIGS. 7 and 8 show a further form of the invention characterized by the provision `of a supporting connection hereinafter described, between the sonically vibratory production tubing, designated at 12b in this instance, and

the jacket pipe 11b, in the lower region of the well. This provision excludes the possibility of sand being heaved up for a long distance in the annulus between the produc- 'tion tubing 4and the jacket pipe. The supporting connection may comprise a restriction or pack-off means having practically no motional wear surface on the tubing such presently.

as may be prone to deterioration in service. In addition, such connection is preferably arranged to carry the weight of the sonic production tubing, thus eliminating the need for the spring support means of the earlier described embodiments. Still further, and as a further feature, the support point and connection means are preferably located in a region spaced one-quarter wave-length up from the lower end of the tubing string, so as to be at a node or pseudo-node of the tubing string, and thus have minimized vibration amplitude. Such quarter wave (tt/4) location is represented in wave diagram in FIG. 7. In this way, lthere need' be little or no provision for resilient support of the tubing string, over and above the resiliency provided by or inherent in the jacket pipe.

Referring specifically to FIGS. 7 and 8, -the vibration generator or oscillator, which may be the same as the generator G of FIG. 1, is indicated in this instance at Gb, and is shown mounted on tting screwed on to the upper end of tubing string 12b. This tubing string 12b is again made up of lengths of resilient pump tubing connectcd by coupling collars, here designated at 52h, which will be understood to contain fluid impelling and check valve units such as units S0 of FIG. 2. One of the tubing coupling collars 5211', in the lower portion of the well, has a special additional configuration to be described The lowermost tubing coupling collar 52h" has coupled thereto a short length of tubing 12b', which functions as the well Huid intake means into the pump tubing 12b.

As in FIG. 1, the well includes a casing 10b extending down into earth structure 8b to .the productive formation, and a return ilow jacket pipe 11b which is annularly spaced inside casing 10b by annulus or annulus space 45h, and which somewhat closely but loosely surrounds the tubing string and its coupling collars 52b, so as to afford an annulus 36h.

At the top of casing 10b and jacket pipe 11b is a suitable casing head structure Cb, and on top of the latter is a stufng box 13b which packs or seals the pump tubing where it leaves the casing head.

The production fluiddelivery pipe line 30h, again preferably including 'a flexible hose section, as illustrated, is coupled into fitting 131) so as to communicate with the upper end of sonic pump tubing string 12b, and its delivery line lead-s to sand trap 32b. The trap 32h again comprises a tank 36C having therein a transverse partition 37b forming a sand settlement compartment 38h and a compartment 391; for relatively cleaned well iluid which has passed over the edge of partition 37b. Tank 36e has an outlet pipe 41111 for delivery of cleaned well iiuid from the well, `and two

additional outlet pipes

132 and 133, the former containing control valve 134 and the latter a control valve 13S. Pipe 132 connects into the casing head so 'as to communicate with the well annulus 3611, and thus return cleaned well fluid down said annulus, under contnol of valve 134. Pipe 133 connects into the casing head so as to communicate with the annulus 46h, and so as to return cleaned well uid down the latter annulus to the bottom of the well, where it can commingle with incoming well fluids flowing into pump tubing intake 12b. -The casing 10b can in this instance eitherv terminate within or short of the productive formation, as in FIG. 1, or might extend downwardly therethrough and be perforated as is common in the art for purpose of well flu-id entry. In this instance, the jacket pipe 11b, however, is shown with an optional lower end construction which may, if desired, be substituted for the lower end jacket pipe section 11 of FIG. 1, or for the arrangement including the packer as shown lin FIGS. 5 and 6. It is of course understood that a lower end jacket pipe termination, perforated, and with a bull end at the bottom, such as shown in FIG. l, or the arrangements lof FIGS. 5 or 6, may be used with the system of FIG. 7 if desired. The lower end jacket pipe might even, in some cases, involve nothing more than a perforated pipe with an open end at the bottom, in view of a novel sand exclusion feature to be described presently. The modified jacket pipe member shown in FIG. 7, however, comprises a cap 140 screwed onto the lower end of the jacket pipe 11b and provided at its lower end with an inwardly turned annular flange 141 formed with a central aperture 142 and which retains bushing 145, subsequently described. Seated on the flange 141 and confined at the top by a washer 144 which engages against the lower end of jacekt pipe 11b is a resilient rubber bushing 145 of annular form, with a central bore of such diameter as to form a uid and sand seal to the tubing member 12b', and thus t-o act to exclude sand from entering the annulus around the outside of the member 12b'.

The aforementioned tubing coupling 52b may be so located relative to the lower extremity of the tubing string and to the vibration frequency of the sonic generator Gb as to coincide substantially with a node, or pseudo-node, of the standing wave set up in tubing string, and preferably, the lowermost such node or pseudo-node. The tubing couple 52b, in common with the coupling members 52h above and the coupling member 52b below, will be understood to optionally contain a fluid check valve unit such as shown in FIG. 3. In addition, the coupling member 52h is formed with an external annular ange 148 (see also FIG. 8).- Immediately around the tubing coupling member 52b is a special jacket pipe coupling collar 70b which is formed with an internal annular flange 150 underlying and supporting the external :annular fiange 148 on the coupling member 52b. The flange 150 may engage and support the flange 148 directly, or preferably, and as illustrated, there may be interposed therebetween a suitable rubber annulus 152, which is confined enough to deform resiliently to only a moderate extent under the compressive pressure exerted by the ange 148 and the tubing string. The resilient annulus 152 will be seen in FIG. 8 to be lodged between the fiange 148 and the ange 150, to be confined internally by the coupling of member 52b and to be supported externally by the lower end portion of the adjacent jacket pipe 11b. It may now be seen that the entire tubing string is vertically supported by tbe engagement of flange 14S with the fiexible rubber annulus 152 seated on the annular supporting flange 150 Which extends inwardly from a coupling collar in the jacket pipe 11b. In short, the tubing string 12b, and the v-ibration generator on the top end thereof are in this instance supported by the jacket pipe 11b which is in turn suspended from the casing head mounted on the top end of the earth-engaging casing b. The jacket pipe 11b being somewhat resilient, and the annulus 152 also being of a resilient compound, the tubing string 12b can have a degree of local vibratory vertical reciprocation in the region of the coupling member 52b such as is readily accommodated by these resilient properties of the annulus 152 and the jacket pipe. However, particularly if, as if preferable, the tubing coupling member 52b is located at a quarter wavelength distance up from the bottom end of the tubing string, the vibration amplitude at the coupling member 52b is small and very easily accommodated, and there is minimized vibratory working within the rubber annulus 152 and/ or by the jacket pipe 11b.

It will be seen that the engagement of the flange 148 with the fiange 150, with or without the preferred rubber annulus 152, closes off the annulus space 36h above the coupling member 52b' from the corresponding annulus space below said coupling. To permit optional fiuid flow downwardly in the annulus 36b past the thus tight or sealed connection between the tubing string and the jacket pipe in the region of the coupling member 52b, I may provide a fluid passage 154 in the lower end of the tubing section immediately above the coupling member SZb, which conveys the fluid in the annulus 36b above downwardly past the upper portion of the annulus 152 to the annular space 156 inside the coupling, and I may also provide a fluid passage 157 which leads from the space 156 through the ange 150 to the annulus space 36b below the coupling member 52b'.

I also preferably provide one or more fluid intake ports leading from the fluid recirculation annulus 36b into the pump tubing string 12b. As here shown, two

such intake ports

158 and 159 are located in the sections of tubing 12b immediately above and below the illustrated tubing coupling 52b. Another such fluid intake port 160 is shown to be located in the lower end portion of the tubing section immediately above the lowermost tubing coupling 52fb. Finally, two more such

fluid intake ports

162 and 163 are shown in FIG. 7 to be located in the sections of tubing string 12b near the typical tubing coupling 52b. It will be understoodthat as in earlier described embodiments of the invention, well flu-.ids returned down the annulus Sb will be taken in through these several intake ports such as 15S to 1&3, and commingled with the well fluids rising in the tubing string 12b, in accordance with the basic principles of the recirculation type sonic sand pump of the invention. It will of course be clear that a quantity of such fluid recirculated down the annulus 36b may run past the otherwise uid-tight connection between the jacket pipe and the pump tubing string at the tubing string coupling 52b, fiowing yfor this purpose through the passage 154, the space 156, and the passage 157. The last mentioned fluid can be intaken into tubing string 12b via the intake ports 159 and 169. The seal between the jacket pipe and the pump tubing effected by the rubber bushing is preferably made substantially fiuid tight, so as to exclude intrusion of sand up into the annulus space between the jacket pipe and tubing string. On the other hand, it is also feasible to provide only a loose seal or fit between the bushing .145 and tubing member 12b. In such case, a small flow of recirculation fluid may be permitted to pass downwardly around the lower end portion of the intake tubing member 12b', where it commingles with incoming well fluid and rises with the latter in the pumpy tubing string. This fiow tends to prevent intlrusion of sand, and also to wash out any sand which may have entered past the bushing 145.

In the event of cave-in or heaving, sand from the formation is thus either completely or substantially prevented from rising to and past the sealing means at 145. On the other hand, assuming use on the lower end portion of the jacket pipe of, for example, a perforated but openended pipe member, sand might, in case of rsevere cave-in, 'enter relatively high into the annulus space between the jacket pipe and the tubing string. In such event, the tight -connection between the tubing coupling member 52b and the jacket pipe serves as a positive final sand barrier; and this would be true also in a modified form of the invention wherein said tight connection were to be made at a considerably lower elevation than appears in FIG. 7. In other words, the structure at coupling 52b' affording the tight connection in question could, in a modified form of the invention, be installed at considerably below the quarter wavelength elevation above the lower extremity of the tubing string, even in the region of the lower extremity of the tubing string. In such case, of course, there is a substantially increased amplitude of vibration in the jacket pipe string at the point of the tight connection. However, this can be readily accommodated within either or both of the resilient annulus 152 and the somewhat resilient jacket pipe 11b. Also, of course, the bushing 145, when made or fitted to seal effectively to the tubing member 12b', affords a sand excluding tight connection.

The resilient bushing 145 thus preferably acts, in effect, as a substantial closure or barrier means against incoming sand; and this closure means may have an actual friction sliding engagement with the pump tubing, so as to afford a very effective sand exclusionary function. It is also possible, however, to permit some circulation of well iluid down the annulus and out through a small annular clearance space between the bushing 145 and the pump extremity 12b'. With a thoroughly tight seat at bushing 145, recirculation in accordance with the invention is still accommodated by the recirculation uid intake ports in the pump tubing string. Bushing 145 may alternatively be made soft enough, and with a sufficiently tight tit on tubing member 12b', to take a rm grip on the latter, and simply resiliently deform to accommodate the vibration at the lower end ofthe tubing string.

As in all of the above described variations of this invention, there is a wall means providing a barrier between the well fluid, with its sand, and the annulus provided by the jacket pipe around the pump tubing. vAs explained above, this barrier `or restriction may be a perforated pipe wall, a resilient packer, a bushing, a solid shoulder or flange, or any other flow stopping or` restricting means.

FIG. 9 shows a further moditication of the lower end portion of the jacket pipe. stance designated generally by reference numeral 11C. A fragmentary lower end portion of the sonic pump tubing is indicated at 12C, and this sonic pump tubing is terminated somewhat in the manner of FIG. 4, with a uid impelling and check valve means 50c carried by the terminal coupling member 52e. According to the modiiication of FIG. 9, the jacket pipe 11C has a bottom end closure means and How-restricted intake means in combination forming the barrier means, embodied in a check valve device 170, which, in general physical rnakeup, may be identical to the check valve units 50 such as shown in detail in FIG. 2 and described hereinabove. A lower end `shell 171 screwed onto the lower end of pipe 11c has an inturned annular ange 172 forming an intake port 173 in the bottom. This intake port 173 is tiow-restricted by the mounting of the check valve unit 170 thereabove, it being seen that the check valve body 174 is seated on the shell iiange 172, and confined in position by rubber rings or sleeves 175 which engage its outer periphery, and are in turn conned and positioned by a spacer member 176 contained inside the shell 171. It will be understood that the spacer member 176, though appearing :soli-d in the sectional view in FIG. 9, may be skeletonized for lightness.

Considering the operation of the embodiment of FIG. 9, it will be seen that the movable lcheck valve element 61C will rise to admit well fluids from outside the jacket pipe whenever suction is developed in the region immediately thereabove by reason of cyclic low pressures generated below the lower end portion of the sonic pump tubing. On the alternate positive pressure pulsesthe check valve element 61e is caused to approach toward its seat, so at this time there is reduced iniiow into the jacket pipe, i.e., there is thus restriction to inow. The operation of the pumping system with the modiication shown in FIG. 9 should be evident. Reciriculation flow down the annulus 36d, between the jacket pipe 11e and the pump tubing string 12C, mixes'with well iiuid admitted through the check valve unit 170, and the mixed ilow is intaken into tubing 12C in accordance with the usual pumping performance of the sonic pump. The jacket termination member serves etfectively as a barrier or closure means against free inflow of sand, particularly under heaving conditions, while at the same time acting as a restricted well fluid intake means. Even under conditions of substantial heaving, little sand is likely to rise through the check valve unit 170. What sand does so rise through check valve 170 into the space below the intake end of the sonic pump tubing is picked up by the ricirculation fluid sent down through the annulus 36e and it will be evident that the rate of such recirculation tlow can be increased under sanded conditions to improve the rate at which the sand is carried out Via the pump tubing.

A number of illustrative embodiments of the invention The jacket pipe is in this inhave now been disclosed. It will be understood, of course, that numerous additional modifications may be made within the broad scope of the invention, and that numerous modifications in design, structure, and arrangement may be made without departing from the spirit and scope of the appended claims.

l claim:

1. In a deep well sonic pumping installation for pumping well fluids intiowing from a producing earthen formation to a well bore sunk therein, the combination of:

an elastic pump tubing string extending down into said well bore, and having sonic'fluid impelling means therein,

a sonic wave `generator coupled to said tubing string for applying sonic elastic vibrations to said tubing string in a direction-longitudinally thereof,

a jacket pipe in said well bore around the lower end portion of said pump tubing string in the region of said producing formation, said jacket pipe being spaced from said pump tubing string to afford an annulus therebetween.

wall means extending inwardly from said jacket pipe so as to providey a sand barrier between said tubing string and said inliowing well fluid,

a source of recirculation fluid, and

flow conduit means connecting said recirculation fluid source to said annulus.

2. The subject matter of claim 1, wherein said wall means comprises a perforated pipe member which surrounds and cages the lower end portion of said pump tubing string.

3. The subject matter of claim 2, wherein said perforations are located below substantially the lower extremity of said pump tubing string.

4. The subject matter of claim 1, including a well casing in said well bore extending down in the well bore to said producing formation.

S. The subject matter of claim 4, including also means u for delivering a fluid downwardly in the well between said jacket pipe and said well casing to the region of said wall means.

6. The subject matter of claim 1, wherein said sonic fluid impelling means includes two vertically spaced fluid impelling and check valve units in said pump tubing string, and said pump tubing string has, between said units, a fluid intake port for admitting fluid from said annulus into the tubing string.

7. The subject matter of claim 1, wherein said sonic iiuid impelling means includes two vertically spaced fluid impelling and check valve units in said pump tubing string, and said pump tubing string has, between said unitsJ a uid intake port. for admitting fluid from said annulus into the tubing string, and

check valve means controlling said uid intake port, said check valve means being arranged for opening response to negative pressure pulses inside the tubing string and for closing response to positive pressure pulses within the tubing string.

8. The subject matter of claim 1, wherein said wall means affording said sand barrier embodies a fluid intake check valve exposed to said well fluids.

9. The subject matter of claim 1, wherein said wall means is supported by said jacket pipe, and in turn supportingly engages said pump tubing string.

10. In a deep wel] sonic pumping installation for pumping well iluids from a well bore sunk into a producing earthen formation, the combination of:

an elastic pump tubing string extending down into said well bore, and having sonic uid impelling'means therein,

a sonic wave generator coupled to said tubing string for applying sonic elastic vibrations to said tubing string in a direction longitudinally thereof,

a jacket pipe surrounding said pump tubing string in the region of said producing formation, said jacket pipe being spaced from said pump tubing string to afford a well annulus therebetween,

:an annu-lar fluid flow restriction means between said jacket pipe and said pump tubing string and arranged for sliding, fluid-flow-restrictive engagement with said pump tubing string,

said pump tubing string having fluid intake port means therein communicating with said well annulus above said annular fluid flow restriction means,

a source of recirculation fluid, and

flow conduit means connecting said fluid source to said well annulus.

11. In a deep well sonic pumping installation for pumping well fluids from a well bore sunk into a producing earthen formation, the combination of:

an elastic pump tubing string extending down into said well bore, and having sonic fluid impelling means therein,

a fluid barrier in said jacket pipe across the annulus `between said jacket pipe and said pump tubing string,

said pump tubing string having fluid intake port means communicating with said well annulus above said barrier,

a source of recirculation fluid, and

flow conduit means connecting said fluid source to said well annulus.

12. In a deep well sonic pumping installation for pumping well fluids from a well bore sunk into a producing earthen formation, the combination of an elastic pump tubing string extending down into said well bore, and having sonic fluid impelling means therein,

a jacket pipe surrounding said pump tubing string in the region of said producing formation, said jacket pipe being spaced from said pump tubing string to aflord a well annulus therebetween,

a fluid barrier in said jacket pipe across the well annulus between said jacket pipe and said pump tubing string in the lower region where entering sand tends to impede said sonic vibrations of said tubing string, and

there ybeing a restricted fluid passage through said `barrier between portions of the well annulus above and below said barrier,

13. The subject matter of claim 12, wherein said pump tubing string has fluid intake port means exposed to well fluids in said portion of the Well annulus below said barrier.

14. The subject matter of claim 13, including fluid flow restriction means in said portion of said well annulus below said barrier, and below said fluid intake port means.

15. In a deep well sonic pumping installation for pumping well fluids inffowing from a producing earthen formation to a well bore sunk therein, the combination of:

an elastic pump tubing string extending down into said well bore, and having sonic fluid impelling means therein;

a sonic wave generator coupled to said tubing string for applying sonic elastic vibrations to said tubing string in a direction longitudinally thereof;

a jacket pipe in said well bore around the lower end portion of said pump tubing string in the region of said producing formation, said jacket pipe being spaced from said pump tubing string to afford an annulus therebetween;

wall means on said jacket pipe formed to provide a sand lbarrier between said annulus and said inflowing well fluid, which wall means embodies a fluid flow restricting means situated in said annulus between said jacket pipe and said pump tubing string;

a source of recirculation fluid; and

flow conduit means connecting said recirculation fluid source to said annulus.

16. The subject matter ofclaim 1S, wherein said fluid flow restricting means embodies a packing to the pump tubing which is effective as a fluid seal to hold a column of fluid thereabove to a given height in said well annulus.

17. The subject matter of claim 15, wherein said pump tubing string has a fluid intake port communicating with said annulus `above said fluid flow restricting means.

1S.. The subject matter of claim 1S, wherein said pump tubing string has a check-valved fluid intake port communicating with said annulus above said fluid flow restricting means.

19. The subject -matter of claim 15, wherein said fluid flow restricting means comprises a fluid packing element between said jacket pipe and said pump tubing string.

2t). The subject matter of claim 15, wherein said fluid flow restricting means comprises a sliding bushing between said jacket pipe and said pump tubing string.

References Cited by the Examiner UNITED STATES PATENTS 2,244,256 6/1941 Looman 103--1 2,766,450 4/1955 Bodine 103-1 3,127,842 4/1964 Bodine 103-1 LAURENCE V. EFNER, Primary Examiner.

Claims

1. IN A DEEP WELL SONIC PUMPING INSTALLATION FOR PUMPING WELL FLUIDS INFLOWING FROM A PRODUCING EARTHEN FORMATION TO A WELL BORE SUNK THEREIN, THE COMBINATION OF: AN ELASTIC PUMP TUBING STRING EXTENDING DOWN INTO SAID WELL BORE, AND HAVING SONIC FLUID IMPELLING MEANS THEREIN, A SONIC WAVE GENERATOR COUPLED TO SAID TUBING STRING FOR APPLYING SONIC ELASTIC VIBRATIONS TO SAID TUBING STRING IN A DIRECTION LONGITUDINALLY THEREOF, A JACKET PIPE IN SAID WELL BORE AROUND THE LOWER END PORTION OF SAID PUMP TUBING STRING IN THE REGION OF SAID PRODUCING FORMATION, SAID JACKET PIPE BEING SPACED FROM SAID PUMP TUBING STRING TO AFFORD AN ANNULUS THEREBETWEEN. WALLS MEANS EXTENDING INWARDLY FROM SAID JACKET PIPE SO AS TO PROVIDE A SAND BARRIER BETWEEN SAID TUBING STRING AND SAID INFLOWING WELL FLUID, A SOURCE OF RECIRCULATION FLUID, AND FLOW CONDUIT MEANS CONNECTING SAID RECIRCULATION FLUID SOURCE TO SAID ANNULUS.