US2083687A - Deep well pump - Google Patents

Description

June 15, 1937. R. L. cHENULT l DEEP WELL PUMP Filed Sept. 4, 1956 Patented June 15, 1593.7

UNITED STATES DEEP WELL PUMP Roy L. Chenault, Pittsburgh, Pa., assignorto Gulf Research & Development Company, Pittsburlh,

Pa., a corporation of Delaware Application September 4, 1936, Serial No. 99,477

4 Claims.

This invention relates to deep well pumps, and it comprises a pump for Aoperating under high submergence heads, for lifting liquid insuccessive slugs by the pressure and lifting effect of gas introduced into the pump from the'surface oi the well, with means forI initially ejecting liquid from the pump when positioned in the well, without resort to high pressure of gas for that purpose, whereby a normal operating condition can beestablished within the pump and its operationl started notwithstanding its submergence to deep levels; all as more fully hereinafter set forth and a's claimed.

The general type of pump of which this is yan improvement is disclosed in'my prior Patents No.

1,890,720 and No. 2,059,508. It is particularly adapted for oil well operation wherein the oil israised in stages and is'discharged in successive slugs to the well surface. To this end the oil is admitted to a submerged displacement chamber through an inlet valve, after which the inlet is closed and gas is admitted to the chamber through ports uncovered in the reciprocation of a valve piston, forcing the oil upwardly from the displacement chamber to a point where, upon reverse reciprocation of the piston and consequentuncovering of a different seriesv of ports, it is picked up by the gas, then admitted to the eduction pipe of the pump, and is discharged to the Asurface in'slugs of va weight commensurate with the pressure vof gas available at the well for operations. v

In many wells in which it is desirable to use a pump of this type the fluid level may be several thousand feet and it is advantageous to submerge the displacement chamber under this full depth of liquid. In positioning the displacement chamv In the older types it was necessary to displaceI the entire cont'ents of the outer string of tubing and displacement chamber into the inner, or flow string when starting. This generally resulted in creating a head of oil in the iiow string several times as great as the submergence head of the (Cl. S-231) pump, and accordingly higher gas pressure was required to initiate flow. The type of pump with which my aforesaid inventions are concerned constitutes an improvement in that the liquid after being raised in the ow string to an intermediate height by gas pressure is picked up by gas injected into the flow string and is discharged. in slugs to the'surface. With this type of pump it is not necessary to add'the contents of the displacement chamber to that of the flow string when starting. However, under conditions of high submergence and with the relatively large diameter tubing such as is required in wells of great depth, the'kick-off pressure may become excessive even in the improved type of pump, yfor the voil in the annulus Within the outer string of tubing must be displaced into the inner string which constitutes the eduction pipe, and in starting the head of liquid in the eduction pipe may f be several times as great as the submergence head.

It is accordingly an object which is achieved by my invention to provide a pump comprising inner and outer tube strings each with a series of ports and passages, certain of which are adapted to be brought into communication initially to displace liquid from the annulus between the concentric strings of tubing partly into the inner tube string and partly through the displacement chamber at the lower end of the outer string back into the well. Thereafter, such communication between the ports is closed. In subsequent normal pumping liquid is admitted to the displacement chamber through a valved inlet which is then closed by reciprocation of the. inner tube string while communication is established with a source of gas under pressure to force liquid from the displacement chamber upwardly into the inner string to an intermediate level. It is there picked up upon reverse movement of the inner string by gas which is now injected into the eduction pipe and is discharged in a slug to the surface while in the same movement of the inner .tube string the inlet valve is again opened and. 'the displacement chamber refilled.

Figure 2 is an enlarged view in longitudinal lsection of that part of the pump within thereach of bracket A, Figure 1, and in the position there shown.

Figure 3 is an enlarged longitudinal section similar to Figure 2, but showing the pump in the lower normal working position, or in other words, in the down position of its valve piston.

Figure 4 is -an enlarged longitudinal section, similar to Figure 2, but showing the pump in the upper normal working position or in other words, in the up position of its valve piston.

Figure 5 is a transverse section taken along the line 5 5 of Figure 1.

Referring more particularly to the drawing, the pump assembly comprises an outer string of tubing II) within which an inner tube string II is concentrically mounted. Each tube string is composed of axially aligned and connected sections which dene an enlarged annular space I2 above the threaded nipple I3 in the outer string and a second enlarged annular space I4 below it.

The nipple I3 has opposite tubular extensions I5 and I6 which together comprise an elongated cylinder spaced from the Walls of the adjoining upper and lower sections ofthe outer tube string to define passages I1 and I8 which have ports I9 and 20 respectively, extending into the bore of the cylinder. A valve piston 2I forms an element of the reciprocable inner string and is received in the cylinder I5, I6. This valve directs the flow of gas for discharging the pumped liquid in stages to the surface of the well. In order to accomplish its purpose the piston 2i is reduced inI diameter between the packed heads 22, 23 and 24, and is formed with ports 25 com municating between its hollow bore 25 and the space 21 which extends between the packed heads '22 and 23.

The lower end of the piston,carries a check valve 28 (Figure 1) from the housing of which a jointed tubular extension 29 depends, such extension having ports 30 immediately above its lower end, and mounting a packed piston 3| Vat its lower end. 'I'he piston 3| reciprocates in acylinder 32 which has inlet ports 33 and which is connected to an enlarged displacement chamber 34 by a reducing nipple 35.

At its upper end thevalve piston 2| is'coupled to the adjoining section of the inner tube string by an internally threaded collar 36. This collar is of larger diameter than the piston and provides a shoulder which limits the extreme downward movement of the piston by abutting against the cylinder end I5, as shown in Figures 1 and 2.

The opposite cylinder end I6 is formed with a plurality of radial bosses31 (Figures 1 and 5) each of which has an axial passage threaded to receive a coupling nipple. 38 which passes through the wall of the outer tube string. The coupling nipples 38 have bevelled heads which are flush with the surface of the section of tubing 38 through which they project. A series of radial ports is thus provided for communication between the space 40 around the valve piston and the interior of the well casing 4I.

The vinner tube string II extends upwardly through a packing 42, at the surface, and is reciprocated by mechanism, not shown, to actuate the valve piston and inlet valve. The outer tube string III has a branch pipe l43 through which gas is forced into the pump and is directed by the valve piston in its various positions, first to remedy any flooded condition of the pump, and subsequently to carry onvnormal pumping.

In-operation, the pump is, assembled in the usual manner by first lowering the outer tube string into the well, the oil or other liquid to be pumped meanwhile rising in and around it to the well level. The inner tube string is next lowered within the outer string and this too fills with oil.

Initially, the inner string is lowered until coupling collar 36 abuts the end of the valve cylinder in which position both the inner and outer strings communicatewith the well. 'I'he inner string communicates with the well through ports 25, space 21, ports 28, space I8 and thus through the displacement chamber to ports 33. The displacement chamber communicates with the 'well through ports 3,3 at its lower end. The valve ports I9, 20 and 25 are also in communication in this extreme position of the inner string. Gas under pressure now enters the annular space I2 between the inner and outer strings of tubing and is applied gradually so that the bottom hole pressure and the formation pressure will have time to equalize while the oil above ports 25 is displaced downwardly and nds its way back to the well through -open ports 33 in the displacement chamber. Most, if not all, of the oil so returned to the well will pass back into the formation, but even if it does notentirely do so, there will be a negligible gain in head in the well casing because of its large volume as compared to that of the annulus. Furthermore, little or no oil from the annulus will be added to that in the inner string of tubing. If it were the head would be greatly increased because of the smaller volume of the inner string and in consequence it would be more difficult to initiate flow to the surface.

Continued application of gas pressure eventually displaces oil from the annulus downwardly to the level at which ports 25 are uncovered, whereupon gas enters the inner string of tubing and raises the oil above those ports to the surface by gas lift. With the escape of gas to the inner tube string in this manner, the return of oil from the annulus to the well ceases and, instead, oil from the Well thereafter flows through open ports 30 and pastv valve 28, rising in the inner tube string to a level above the ports 25 so that the gas lift, having been initiated continues and large volumes of raised to the surface. The oil level in the well casing thereupon recedes to the level shown in Fig. 1 of the drawing at which point the liquid can be lifted eithernot at all or only ineiciently by gas lift. Thev inner tube string is then positioned for reciprocation in normal pumping.

In the extreme lowered position of the inner string a means is provided for temporarily forcing the contents of the annulus back into the well. inl increasing the submergence head yet it obviates adding the annulus contents to the inner tube string and so making it more difficult to start flow to the surface under the low gas pressures ordinarily available at the well.

'I'he various positions in which the inner tube string may be placed make it possible to initiate the flow of oil with low pressure and under high submergence-conditions by'gas lift until the submergence is so low that pumping is desirable, whereupon the inner string of tubing is raised` to the position in which the intermediate head 23 of the valve piston cuts otf communication between the ports I 9 and 20 by way of the passage 21. (Figure 3.) This position then is established as the lower limit of pump stroke in the ensuing pumping operation. In it the foot valve is oil are rapidly'.

The oil so expelled has little or no effect 'aus The oil in theI displacement chamber is there-- upon forced through the open'ports 30 in the inner tube string and upwardly in the eduction passage past the ball check valve 28.

The inner string is again lowered to its normal down position (Figure 3) in which the head 23 of the piston cuts off the flow of gas to the displacement chamber and instead 'establishes its passage through the annulus I2, space I'I, ports I9 and space 21 around the valve piston to the ports 25. At this point it is injected into the column of oil which was raised above the check valve 28v on the previous lup stroke and discharges this limited quantity of oil to the surface by gas-lift, in the form of a slug of such weight that it can be lifted by the available gas pressure.

At the same time the foot valve. is again opened and oil from the well flows into the displacement chamber, lling it and forcing the previously used gas from it and upwardly through space I8, ports 20 and into space 40 around the valve piston, this space being now in open communication with the well casing 4I through exhaust ports 44. Thus, the gas expelled by inilowing oil from the 'well passes through the space 40 and out into the well by way of the radial ports M in bosses 3l. y

In the downstroke position oil is discharged from the eduction pipe by gas-lift while at the same time the underlying displacement chamber is refilled and its contained gas is expelled. In the upstroke position the gas-lift is cut 01T and pressure is applied, instead, upon the oil in the displacement chamber forcing it up into the eduction passage to the point where it will be picked up and similarly discharged to the surface by gas-lift upon the next succeeding down stroke.

Excessive pressures are therefore not required for raising the liquid from deep wells in stages, and kick-off can be accomplished at lower pressures with a given submergence, even though when the pump strings are lowered into the well they are initially filled to a high level with the liquid.

What I claim is:

1. A deep well pump comprising a tube string, a displacement chamber carried thereby to extend into the liquid in a well, a source of pneumatic pressure, a reciprocable eduction pipe within said tube string which may be lowered to an extreme position outside the normal limit of its reciprocation, valve means normally actuated by reciprocation of the eduction pipe for alternately admitting liquid from the well to the displacement chamber while venting the same and. expelling such liquid therefrom under pneumatic pressure from said source in normal operation, said valve means having an elongated passage communicating with the interior of said eduction pipe and establishing through communication from said source of pneumatic pressure to the well in the extreme lowered position of'said -eduction pipe, thereby in such lowered position of the eduction pipe to eject liquid trapped in the pump under pneumatic pressure not substantial- I ly exceeding that required for succeeding normal pump operations.

2. A pump for operatingunder high submergence heads and. for delivering successive and substantially uniform slugs of liquid to the surface of a well by pneumatic pressure, wherein liquid at a high level in the pump may be expelled under normal working pneumatic pressures preparatory to pumping, which pump comprises a tube string, a displacement chamber carried by said tube string and adapted to extend into the liquid of the well, a valved inlet in said displacement chamber for intermittently admitting well liquid thereto, an eduction pipe reciprocable within said tube string and communicating with said chamber at its lower end, a source of pneumatic pressure, valve means actuated by said eduction pipe in normal reciprocation betweenl determined upper and lower limits for alternately connecting first the displacement chamber and then the eduction pipe with the source of pneumatic pressure, said valve means having a passage which an extreme position of said eduction pipe outside the normairange of its reciprocation establishes direct communication of the source of pneumatic pressure with both the eduction pipe and the displacement chamber, whereby/When the valve means is so disposed in its extreme position liquid which is trapped at a high level in the pump will be expelled in part through the eduction pipe and in part back through the displacement chamber to the well under the pneumatic pressurei'equired only for normal working, after which said valve means is positioned to assume its normal extremes of reciprocation in operation ofthe pump to discharge successive slugs of liquid. 4

3. A pump for operating under high submergence heads and for delivering successive slugs u of liquid to the surface of a well by pneumatic pressure, wherein liquid at a high level in the pump may be expelled under normal working pneumatic pressures preparatory to pumping, which pump comprises a tube string, a. displacement chamber carried by said tube string and adapted to extend into the liquid of the well, a valved inlet in said displacement chamber for intermittently admitting well liquid thereto, an eduction pipe normally reciprocable Within said tube string between upper and lower limits and communicating with Said chamber at its lower end, said eduction pipe being movable to a third position beyond the normal range of yits reciprocation, a check valve in said eduction pipe for retaining liquid forced therepast from said chamber, a source of pneumatic pressure, va hollow, ported valve carried by said eduction pipe, said valve having a packed piston and being of reduced diameter above and below such piston to dene spaced, uncommunicating passages, a cylinder carried by said tube string having ports level in the pump will be expelled in part through the eduction pipe by pneumatic-lift and in part back through the displacement chamber to the well under the pneumatic pressure required only for normal working, after which the said valve may be positioned to assume its, normal extremes of reciprocation in operation of the pump.

4. A deep well pump comprising inner and outer strings of tubing, an inlet valve at the lower end thereof controlled by reciprocation of the inner tube string to admit well liquid to the pump, a displacement chamber in the outer tube string into which the admitted well liquid ows, a ported piston and cylinder carried by the inner and outer tube strings, respectively, theA ports thereof beingso arranged that initially in an extreme down position of the piston beyond the,

normal limits of its reciprocation, liquid which is trapped in the pump during its submerged assembly may be expelled by gas pressure, upwardly through the inner tube string and downwardly through the displacement chamber into the well,

whereafter the normal Aworking limit of downstroke may be established so that with the inlet valve of the displacement chamber open the said piston cuts said chamber oi from communication with the gas supply, and directs the gas, instead, through the respective ports then in communication, into the inner tube string to discharge oil upwardly therethrough by gas-lift, the said piston in its upstroke position closing the inlet valve of the displacement chamber and permitting flow of gas to the said displacement chamber to discharge liquid therefrom upwardly into the inner tube string from which, upon the next down stroke, such liquid will be discharged by gas in- 15 .iected thereinto.

ROY L. CHENAULT.

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