US2859827A

US2859827A - Apparatus for treating wells

Info

Publication number: US2859827A
Application number: US397322A
Authority: US
Inventors: Lloyd E Elkins; Renic P Vincent
Original assignee: Pan American Petroleum Corp
Current assignee: Pan American Petroleum Corp
Priority date: 1953-12-10
Filing date: 1953-12-10
Publication date: 1958-11-11
Anticipated expiration: 1975-11-11

Description

Nov. 11, 1958 E. ELKINS ETAL APPARATUS 'FOR TREATING WELLS Filed Dec. 10, 1955 5 Sheets-Sheet l FIG. 2

LLOYD E. ELKINS RENIC P VINCENT INVENTORS BY A ATTORNEY FIG.

Nov. 11, 1958 L. E. ELKINS ETAL APPARATUS FOR TREATING WELLS 3 Sheets-Sheet 2 Filed Dec. 10, 1953 4 8 8 M "m 4 rfilllul/ln v ATTORNEY L. E. LRlNs ETAL APPARATUS FOR TREATING, WELLS Nov. 11, 1958 3 Sheets-Sheet 5 Filed D60. 10, 1955 1N VEN TORS T1-\\\\\& MI H fl w w.. w

FIG. 5

I ATTORNEY Unite APPARATUS FOR TREATING WELLS Application December 10, 1953, Serial No. 397,322

8 Claims. (Cl. 166-465) This invention relates to an apparatus for injecting a treating agent into a well. More particularly, this invention is directed to an improvement in the art of dispensing a corrosion inhibitor in the well fluids near the bottom of a well so that the complete tubing string and other apparatus in a well are protected from corrosion.

In the producing of oil from deep wells, it is often desirable to inject a treating agent into the well or into the well fluids nearer the bottom of the well. For example, it is often desirable to inject an oil-water demulsifying agent into the well fluids near the bottom of the well so that the formation of an emulsion within the well may be prevented or so that emulsions formed before the fluids enter the well may be readily broken within the well.

One of the most commonand perplexing problems in the production of oil wells is the corrosion of the tubing and other pumping apparatus within the well. Various corrosive agents such as acidic gases, notably hydrogen sulfide, carbon dioxide, and the lower organic acids are produced by many wells. In the case of gas lift wells, particularly those produced with an oxidizing gas, oxidation corrosion of the production tubing, gas lift valves, and the like is also a major cause of considerable down time and expense.

' Various corrosion inhibiting treating agents have been injected into such corrosive wells. These corrosion inhibitors comprise the gaseous, liquid, and solid phases of various materials. For example, the volatile amines, ammonia, and the like have been injected into wells to neutralize acidic corrosion. Liquid solutions of corrosion inhibitors such as formaldehyde and solid compositions including various amines andother neutralizing or wetting agents have been injected into wells to overcome various causes of corrosion. In some cases, these inhibitors can be injected into the annular space between the casing and tubing and circulated down around the end of the tubing and back up through the inside of the tubing with the well fluids whereby the complete well apparatus can be contacted by the inhibitor and protected from corrosion. In many cases, however, as, for example,in dually-completed wells or wells otherwise employing a production packer, it is often difllcult if not impractical to circulate the corrosion inhibitor to the bottom of the well so that the complete tubing string and other producing equipment below the packer can be protected. In gas lift wells, both those equipped with a tubing packer and those which produce without a packer, the protection of the tubing and casing strings below the gas injection valveis generally impractical since the inhibitor which is introduced into the annular space where the lifting gas naturally flows with the lifting gas through the operating gas lift valve and thus bypasses all producing equipment below that valve.

Various proposals have been made for injecting inhibitors into wells of this type. Oiland water-soluble solid sticks of corrosion inhibitors are sometimes, for example, dropped into the tubing, but inasmuch as these materials generally must be completely soluble in the State Patefit well fluids, it is often necessary to shut the well in so that these inhibitors will fall to the bottom of the-well. If the inhibitor is placed in a heavy container or weights are attached, these materials must be fished from the well when the supply of-inhibitor is dissipated. Such operations require considerable time and expense.

It is, therefore, an object of this invention to provide an improved apparatus for introducing a treating agent into the bottom of a well. It is a more specific object of this invention to provide a container for a treating agent which can be dropped into a well and which subsequently will automatically dispense the treating agent into the well near the bottom of the Well and automatically return to the surface for recharging when the supply of treating agent has been substantially completely :exhausted. This invention will be better understood from the following description in which like reference numbers refer to the same or similar parts in the various embodiments which are here disclosed by way of example for the construction and operation of the invention. ln-this description, reference will 'be' made to-the accompanying drawings in which:

'Figure 1 is a cross-sectional view of a well producing apparatus including an apparatus for dispensing a treating agent at the bottom of the apparatus; and 1 Figures 2, 3, 4, and 5 are cross-sectional views of different embodiments of an apparatus for dispensing a treating agent at the bottom of a well and then automatically returning to the surface for recharging.

This invention in brief consists of an apparatus which may be charged with a well treatingagent such as a corrosion inhibitor and which, when dropped into the tubing of a well, will fall to the bottomof the tubing and there dispense the treating agent into the well fluids over an extended period of time. When the supply of treating agent is exhausted, a packing element is expanded to prevent well fluids bypassing'the dispenser and thus cause the apparatus to be lifted to the surface with the well fluids so that it can be recharged and dropped again to thebottom of a well. .For a more detailed description of this invention, referenceis now made to the accompanying drawings and particularly to Figure l of the drawings.

In Figure 1 a string of tubing '9 is shown in a well which also has a casing 10. A production packer'll is .set between the tubing and casing in the well. At the surface the tubing and casing are connected by a tubing head-12 which supports the tubing in the well and provides a closed annulus 13' between the tubing and casing. The tubing head has a side connection 14 through which, in the case of a gas lift well, gas is injected for lifting the well fluids. A cross pin 15 is placed near the bottom of the tubing to provide a stop for an apparatus dropped into the tubing and prevent it from falling out the bottom of the tubing into the open hole. While this cross pin prevents the apparatus from falling out the bottom'of the tubing, it does not prevent flow of fluid up through the tubing. Optionally, the cross pin may have an upward;- ly projecting valve-actuating mechanism 16 attached for operating a dispenser valve as hereinafter disclosed. The tubing may also be provided at spaced points with external gas lift valves 17 which are lowered with the tubing into the well for controlling the gas injection from the easing into the tubing and for aerating the well fluids and pro ducing the well as well known in this art.

Above the tubing head a master gate 18 is placed in the tubing string for controlling or shutting in the well. The tubing is equipped above the master gate with a 'flow connection, referred to in the art as a flow T or cross :19. One lateral connection on-the cross is plugged with a bull plug 21. In the case of a flowing well, a choke nipple 22 is screwed into the other lateral connection and a flow bean 23, which may be inserted through the opposite lateral connection with bull plug 21 removed, is screwed into, the choke nipple. The flow bean is normally re- -moved"in the case of a pumping or gas lift well. A 'lubricator nipple 24 is screwed into the top of cross 19. This nipple provides suitable space above master gate 18' so that a treating agent dispenser 25 can be placed "in the tubing string above the gate when it is closed. The upper end ofthe lubricator nipple has an internal annular stop 26 for the treating agent dispenser which also seals the nipple and prevents flow when the dispenser is in its uppermost position. A T-27 attached to the upper end of nipple 24 has a side outlet nipple 28 which is connected with choke nipple 22 and flow line 29 by a bypass '30. If it is desired to shut the well in automatically 'whenthe supply of treating agent is exhausted, valve 31 maybe closedand the well produced through the bypass. This bypass also-contains a blow-down valve 32 and a bypass shut-off valve 33. The upper end of T-27 is closed with a plug 34 or, if desirable, by a quick-opening valve or the like (not shown). Referring now to Figures 2, 3, 4, and and specifically to Figure 2, the treating agent dispenser will be described 'in detail. The dispenser comprises generally a container 35 which forms a chamber 36 in which the treatingagent is placed. The container has a small leak or'orifice 37, typically a capillary tube, forming a restricted discharge port through which the contents of chamber 36 are displaced into the well fluids that normally flow up around the container when it is located at the bottom stop in the tubing. A resilient bumper such as spring 38 may be attached, as by welding, to the bottom of the containerfor the purpose of absorbing shock in case the apparatus is dropped into a substantially dry tubing string and falls with great force to the bottom stop. The container also has near the upper end an equalizing port 39 through which well fluids enter the upper chamber 41 as the treating agent is displaced from chamber 36. A piston 42 having an O-ring or other packing element 43 around its periphery is placed in the container between the chamber 36 and the upper chamber 41. This piston is normally urged downwardly by com pression spring 44 which displaces the piston all the way through chamber 36 to the lower chamber head 45. In some instances, the upper chamber may be sealed and filled with a compressible fluid such as air which acts to drive piston 42 and displace the treating agent from thecontainer. Tubular piston rod 46 is connected concentrically to piston 42 and extends through upper chamher head 47 and resilient packer 48. This piston rod has a head 49 at the upper end. A filling connection 51 such as a valved Alemite fitting is threaded axially into head 49 so that a supply of treating agent may be easily attached. The bore 52 in the piston rod forms a fluid connection between the filling connection and the treating agent chamber 36.

The dispenser is shown in Figure 2 in the filled position, i. e., chamber 36 is full of treating agent and the dispenser is ready to be dropped into the well. In this position, spring 44 is compressed and packer 48 is unstressed. When the apparatus is lowered into the well, the piston head 49 is released and spring 44 forces piston 42 down into chamber 36 displacing the treating agent out of orifice 37. The supply of treating agent in the chamber is normally many times the quantity which will be displaced through the orifice as the apparatus falls in the well. For example, in a typical operation the chamber may hold from about 1 to about 25 gallons or more of treating agent which may be displaced through the orifice over an extended period of time, typically from one day to one week or longer. By comparison, the container will fall to the bottom of most wells within a few minutes so that the amount of treating gent di p ed i the well fluids before the apparatus reaches the bottom of the well is substantially insignificant. The outside diameter of container 35 is desirably substantially smaller than the inside diameter of the tubing in which the apparatus is used. The space between the container and the well tubing then provides a flow passage for the well fluids as the container rests on the bottom stop. Treating agent is displaced through the orifice and mixed or intermingled with the well fluids as they flow past the container and up the tubing, thus either preventing demulsification of the well fluids, inhibiting corrosion of the tubing and other well apparatus, or the like. After due time when the treating agent has been substantially all displaced from chamber 36 and piston 42 is approaching lower chamber head 45, piston rod head 49 strikes the upper end of resilient packer 48, and as additional treating agent is displaced from chamber 36, the spring 44 urges piston rod head 49 down compressing the packer axially and expanding it radially or circumferentially. Eventually when the transverse cross-sectional area of the packer 48 is substantially equal to the crosssectional area of the tubing opening, the pressure drop of the well fluids flowing through the annular space be tween the packer and the inside tubing wall is great enough to lift the packer and the attached container. The flow of the well fluids then carries the dispenser up the tubing into the lubricator nipple 24. If bypass valve 33 is opened, the pressure drop across flow bean 23 is great enough to cause some of the well fluids to flow up through the lubricator nipple and the bypass into flow line 29. This bypassed fluid carries the treating agent dispenser to the top of the Iubn'cator nipple so that piston rod head 49vcontacts stop 26 and seals the opening and well fluids can no longer flow through the bypass. Blow down valve 32 is then opened and bypass valve 33 closed so that the tubing head pressure is applied against piston rod head 49 to hold the dispenser in position in the lubricator nipple with filling connection 51 located above the stop 26 in T-27. Bull plug 34 may then be removed and a source of treating agent connected to the filling connection. As the treating agent is injected into the chamber 36 in the dispenser through bore 52, chamber 36 expands forcing the piston rod 46 out of the top of the upper chamber 41 and relieving the axial stress on packer 43so that its diameter and lateral cross-sectional area are decreased. At the same time, the well fluids which were drawn into the upper chamber through equalizing port 39 at the bottom of the well are displaced back into the tubing through the same port. After the chamber 36 has thus been filled, bull plug 34 is replaced in T-27, blow down valve 32 is closed, and bypass valve 33 is opened to equalize the hydraulic pressure across stop 26 so that the dispenser may again fall through the tubing to the bottom stop on another cycle.

In the embodiment of our invention shown in Figure 3, a liquid piston is used to displace the treating agent from the dispenser into the well fluids. In this embodiment the orifice 37 is located in the wall of container 35 near the upper end of chamber 36. This orifice is placed in a plug 53 which may be removed to provide an opening larger than orifice 37 for charging chamber 36 with treating agent. An upper chamber 54 is provided in upper container 55. The two containers are separated by a partition 47. The bottom of chamber 54 is connected via a tube 56 with the bottom of chamber 36. Equalizing port 39 may be placed near the top of the upper chamber or the'upper chamber may be sealed at the upper end and filled with a compressible fluid. This upper chamber is filled with 'a heavy liquid such as mercury which is immiscible with and heavier than the treating agent in chamber 36. The treating agent and mercury form an interface 57 in chamber 36 with the mercury below the interface and the treating agent above the interface. Mandr'el 58 is attached to upper head 47 of the container.

This mandrelis tubular and' forms internally a battery? co'inpa'rtment59. I A number ofstor'age'batteries'61 are' placed in series in this'compartment so that oneterminal 62 contacts the upper end of the insulated conductor 63. The other terminal 64 is connected through solenoid 65 toa ground connection 66. The core 67 within the solenoid 65 by an extension 68 is adapted to compress packer 48 =axially when the solenoid is energized. The battery compartment 59'is sealed with a'removable head 69 so that well fluids cannot get into the battery compartment. The solenoid lead passes'through but is'insulated from head 69.

In operation, the embodiment ofthe invention shown in-"Figure 3 is similar to the operation of the apparatus mercury into upper chamber 54 through tube 56'. Plug- 53 is then replaced in the chamber wall and the apparatus is* dropped into'the well with the-upper or mercuryfilled chamber above treating-agent chamber 36. The mercury in upper chamber 54 being denser than the treatin'g agent, it flows down through tube 56 into the lower end of chamber 36 displacing the treating agent out through the orifice 37. When substantially all of the treating agent has thus been displaced from chamber 36, the mercury below interface 57 contacts the lower end of insulated conductor 63 closing the electrical circuit through solenoid 65. As the solenoid is energized, packer 48is compressed axially and expanded radially to close the space between the packer and the tubing and cause the dispenser to be lifted by the well fluids to the surface. At the surface, the dispenser may be removed from the tubing, recharged as above described, and reinserted into the tubing so that another cycle is commenced.

Referring now specifically to Figure 4, an embodiment ofa treating agent dispenser is described which employs a hydraulically inflatable packing element to seal the tubing when the supply of treating agent has been exhausted. The treating agent chamber 36 contains a valve 71 in the lower head 45. This valve is preferably concentrically located so that it strikes valve-actuating mechanism 16 which is part of the bottom stop in the tubing as described above. This valve consists of a cylindrical stem 72 having a bumper head 73 on the lower end and anut 74 on the upper end. The valve moves axially in bore 75. A packing 76 which may be, for example, an O-ring is provided in bore 75 to seal the valve stem in the bore and prevent leakage of the treating agent from chamber 36 when the valve is in its lower position as shown in Figure 4. When the valve is raised to its upper position as, for example, when the valve bumper head 73 strikes the valve-actuating mechanism at the lower end of the tubing, the weight of the container 35, its contents, and the associated apparatus lowers bottom head 45 onthe valve so that orifice 37 connects the inside with the outside of the container and with the well fluids. By this means, the chamber 36 may be filled at the surface and stored indefinitely or dropped immediately into a tubing and regardless of the rate of descent in the tubing, the treating agent will be sealed in the container until it reaches the bottom stop. Piston 42 is urged down inthe container by spring 44 in the same manner as in the embodiment shown in Figure 2. A hydraulic cylinder 77 is attached to the upper head 47 of chamber 35. A packing 78 is placed in this upper head to provide a seal between the upper chamber 41 and the hydraulic liquid chamber 79., This hydraulic liquid chamber which is enclosed at the top by piston 81 includes a fluid passage 82 which extends down into the inside of the packer 48 which inthis case is hydraulically inflatable. A hole 83 is drilled from this passage into the surrounding annular chamber 84 which is enclosed by the inflatable packer. This packer is anchored at the ends on upper andlowershoulder's 85 by externalclamp bands-86.. Piston F81 has an internal packing 87 whichprovides a- 'seal; between the bore 88 of the piston and the piston: rod 46.. It also has a packing 89 which seals the annular space between the piston and the cylinder 77. Hydraulic liquid chamber 79 and annular chamber 84'are thus connected by'passage 82 and hole 83 and form a completely enclosed constant volume chamber. As the piston is forced down.- into the cylinder 77 by the annular shoulder 91 on pis-' ton rod 46, the hydraulic liquid is forced out of the hy-" draulic liquid chamber through hole 83 into annular chamber 84 causing the inflatable packer 48 to be distended diametrically. The piston rod 46 has an upper piston rod head 49 and a filling connection 51 similar to the apparatus shown in Figure 2.

The operation of this embodiment is similar tothe operation of the embodiments above described. The treating'agent chamber 36 is filled in the samemanner by attaching a supply of treating agent to the fillings connection 51 and forcing the treating agent down through bore52 into the chamber. This raises piston 42 compressing spring 44*and displacing fluid out of upper chamber 41. The hydraulic pressure within the chamber forces valve 71 into a closed position so that the treating agent is not wasted. The apparatus may then be dropped into:

the well tubing. As it falls to the bottom of the tubing,

the valve 71 remains closed. When the dispenser reaches the bottom of the'tubing, the spring 38 contacts cross pin 15 and at about the same time the valve bumper head 73 strikes the valve-actuating mechanism 16 opening the valve so that orifice 37 provides a passage for the treating agent in chamber 36 to escape into the well fluids.

down by spring 44 causing the hydraulic liquid in hydraulic liquid chamber 79 to be displaced through hole 83 and to expand inflatable packer 48. When the pres sure drop of the well fluids flowing around the dispenser is increased by the expansion of this packer until it isgreater than the force required to lift the dispenser, thev dispenser is lifted by the well fluids to the surface; This particular embodiment may also be used with a wellhead apparatus of the type shown in Figure 1. Inthat case, the piston'rod head 49 strikes stop 26 and by proper manipulation of the wellhead connections, as'above'described, the dispenser is held in the lubricator nipple 24 1 while the treating agent chamber is again filled. As the treating agent chamber is filled, piston 42 is displaced upward in the container 35 raising the piston rod and the annular shoulder 91 so that piston 81 is free to rise" in cylinder 77. Inasmuch as the inflatable packer 48 is elastic and smaller in diameter in an unstressed state than when it is distended, this tubular packer forces thebydraulic liquid out of annular chamber 84 through hole- 83 and back into the hydraulic liquid chamber 79 dis placing piston 81 upwardly. When the packing element has thus been deflated and the pressure across step 26 hasbeen equalized, the dispenser falls and another cycle is commenced.

Another and a preferred embodiment of the dispenser apparatus is shown in Figure 5. In this particular em-' bodiment the packer 48 is expanded in a different manner from the methods used in the above-described embodi ments. As in the other embodiments, the packing element is preferably made from a resilient material such as synthetic rubber, preferablyHycar, or the like. The outside diameter of the packer in an unstressed state is desirably approximately equal to the inside diameter of the tubing string. In any case, the force between thepacker in an unstressed state and the tubing wall is-not suflicient to prevent the dispenser from falling when it is filled andlplaced in the tubing string. Thispacke'r may? be an inverted swab rubber or the like which is connected at the upper end to the dispenser and is flared at the lower end to approximately the cross-sectional area of the tubing opening. The upper end of the packer 48 is connected to tube 92 which has a fluid passage 93 connected with the inside of the packer. Exhaust ports 94 are provided in the tube 92 so that well fluids flowing up through the tubing may pass through the inside of the packer and the fluid passage and thence out exhaust ports 94 and around the container 35. These exhaust ports may be closed by a valve 95 which is mounted in the lower chamber head 96 and has a cross-sectional area less than the cross-sectional area of chamber 35. The valve is normally held up and the exhaust ports 94 held open by compression spring 97. The treating agent in chamber 36 is forcibly displaced through orifice 37 by piston 42 which in this case may be weighted or if desired which may be actuated by a compression spring as above described. A heavy piston is sometimes more desirable than a spring for the reason that when the dispenser is falling in the tubing, the weighted piston does not exert as great a force on the treating agent in the chamber as when a spring actuated piston is employed. That is, but for the friction between the dispenser and the well fluids 01" the well tubing, the weighted piston and the dispenser would .tend to fall at the same rate and no hydraulic pressure would be exerted by the weighted piston on the treating agent in the chamber and, for that reason, no treating agent would be displaced through orifice 37 as thedispenser falls through the tubing. The space between piston 42 and the inside wall of chamber 35 is sealed with a packing 43. Chamber 36 below piston 42 is filled from the top chamber head 47 through an axial tube 98. The space between the inside bore 99 of piston 42 and tube 98 is sealed with a packing 101. Packings 43 and 101 thus prevent the treating agent in the chamber 36 from bypassing the piston and becoming intermingled with the well fluids in the upper chamber 41 which enter and exhaust through equalizing port 39. The upper head 47is provided with a face 102 which is, like pistonrod head 49, adapted to seal against stop 26. A shoulder 103 may'also be provided for attaching a fishing tool or the like if desired. The inside bore 104 of head 47 has'a threaded connection 105 at the upper end to which a supply of treating agent may be attached to charge the treating agent chamber 36. The lower end of the bore 104 is closed by a spring loaded check valve 106 which closes upwardly so that a greater pressure may be maintained in the treating agent chamber than the pressure of the surrounding atmosphere or well fluids.

The operation of this preferred embodiment is not substantially different from the operations of the embodiments as above described. The dispenser is filled and lowered into the tubing. Compression spring 97 holds valve 95 open so that well fluids may pass readily through the inside of packer 48 and out exhaust ports 94. The dispenser, therefore, falls to the bottom of the tubing Where it is stopped by cross pin 15. The weighted piston 42 then gradually displaces the treatingagent out of chamber 36 through orifice 37 as well fluids enter equalizing port 39. When substantially all of the treating agent has thus been displaced from the treating agent chamber, the weighted piston strikes the upper head 107 of valve 95, compressing spring 97 and forcing the valve down so that ports 94 and the fluid passage through the packer are closed. Inasmuch as the packer, as above described, preferably has substantially the same crosssectional area in an unstressed state as the cross-sectional area of the hole in the tubing after the fluid passage through the packer has been closed, the pressure drop around the packer through the small annular constriction is substantially increased, thus increasing the pressure on the inside of the packer in comparison to the pressure on the outside. This greater internal pressure then expands thepacker and lifts the dispenser, and it is carried stop 26 is equalized, the dispenser falls freely through the along with the well' fluids to, the surface where it may charged with treating agent, the piston 42 is displaced upwardly in the chamber off of valve head 107 so that compression spring 97 raises the valve and opens port 94. After the chamber is thus filled to open the fluid bypass and deflate the packer and after the pressure across tubing and another cycle is commenced.

From the foregoing it can readily be seen that this invention is not limited to any particular treating agent or to any particular physical state of any treating agent and that with regard to the dispenser itself various modification's can be made without departing from the spirit of this invention. It can also be seen that automatic means may be provided at the well head to recharge the treating agent chamber when it arrives at the upper end of the tubing whereby the treating agent may be dispensed at the lower end of the tubing practically without attention overlong periods of time. While the descriptionhas been directed generally to a process in which the apparatus is recharged periodically at extended periods, in some cases the size of the discharge orifice may be increased so that a treating agent such as bridging materials, cement, or acid may be deposited at the bottom substantially instantaneously either with one trip of the dispenser or with many trips in rapid succession. Such modifications as may be construed to fall within the scope of the appended claims should, therefore, be considered to be within the scope of this invention.

We claim:

1. An apparatus for dispensing a corrosion inhibitor at the bottom of a well comprising a tubing in said well, a bottom stop in said tubing, a top stop at the surface end of said tubing, said tubing at said surface end being provided with a removable closure cap, a fluid outlet in said tubing below said top stop and connected to a flow line, a fluid connection between the top of said tubing above said top stop and said flow line, a valve in said fluid connection, a dispenser movably disposed in said tubing between said bottom and said top stops, a top head on said dispenser adapted to cooperate with said top stop to close the upper end of said tubing, and a filling connection on said dispenser adapted to be positioned adjacent said closure cap whereby said dispenser may be recharged when said tubing is under pressure.

2. An apparatus for dispensing a treating agent in the well fluids flowing up a tubing in a well comprising a container which forms a chamber for said treating agent, a' restricted discharge port in said container to permit said treating agent to flow into said well fluids, displacing means in said container for forcing said treating agent through said port into said well fluids, an expansible flexible sealing means mounted on said container, and means actuated by said displacing means when said treating agent has been substantially completely discharged from said chamber to produce expansion of said sealing means against the inner wall of said tubing when said treating agent has been substantially completely discharged from' said chamber, whereby a pressure differential is produced acrosssaid sealing means to lift said container up said tubing.

3. An apparatus according to claim 2 wherein said displacing means includes a weighted piston.

4. An apparatus accordin to claim 3 wherein said weighted piston has an axial opening therethrough, a charging connection at the upper end of said container,

an axial tube extending from said charging conection duown through said axial opening in said piston to the bottom of said chamber, and a fluid seal in said axial opening and around said. piston to prevent flow of said treating agent .aroundsaidpiston, whereby said container;

may be charged with said treating agent from the top without Withdrawing said apparatus from said tubing.

5. An apparatus according to claim Zwherein said displacing means includes'a piston and resilient means to force said piston into said chamber.

6. An apparatus according to claim 5 including a piston rod connected to said piston and extending axially through said sealing means and a head on said piston rod to compress said sealing means axially as said piston displaces said treating agent from said chamber.

7. An apparatus according to claim 2 in which the cross sectional area of said eXpansible sealing means in an unstressed state is substantially equal to the cross sectional area of said tubing and forms a fluid seal with said tubing, a fluid passage longitudinally through said packer communicating the space above said expansible sealing means with the space beneath said expansible sealing means, and valve means actuated by said displacing means when said treating agent has been substantially completely discharged from said chamber to close said fluid passage, whereby a pressure difierential is produced across said sealing means to lift said container up said tubing.

8. An apparatus for dispensing a corrosion inhibitor in the well fluids at the bottom of a well tubing comprising an elongated container, a piston in said container dividing said container into a lower chamber which may be charged with said corrosion inhibitor and into an upper chamber, a port in the wall of said container at the upper end of said upper chamber for equalizing the pressure in said upper chamber with the well pressure, a restricted discharge port in the wall of said container near the lower end of said lower chamber to permit said corrosion inhibitor to escape into said Well fluids, a packer connected substantially coaxially with said container, the cross sectional area of said packer in an unstressed state being substantially equal to the cross sectional area of said tubing so that said packer forms a fluid seal with said tubing, a fluid passage longitudinally through said packer communicating the space outside said container above the packer with the space beneath the packer, and valve means actuated by said piston upon the displacement of substantially all of said corrosion inhibitor out of said lower chamber to close said fluid passage, whereby a pressure ditferential is produced across said packer and said container is raised in said well by the upward flow of said well fluids.

References Cited in the file of this patent UNITED STATES PATENTS 1,697,114 Green Ian. 1, 1929 2,190,901 Wilcox Feb. 20, 1940 2,588,369 Eilerts Mar. 11, 1952 2,655,996 Earl et al Oct. 20, 1953 2,714,855 Brown Aug. 9, 1955

Claims

2. AN APPARATUS FOR DISPENSING A TREATING AGENT IN THE WELL FLUIDS FLOWING UP A TUBING IN A WELL COMPRISING A CONTAINER WHICH FORMS A CHAMBER FOR SAID TREATING AGENT, A RESTRICTED DISCHARGE PORT IN SAID CONTAINER TO PERMIT SAID TREATING AGENT TO FLOW INGO SAID WELL FLUID, DISPLACING MEANS IN SAID CONTAINER FOR FORCING SAID TREATING AGENT THROUGH SAID PORT INTO SAID WELLS FLUIDS, AN EXPANSIBLE FLEXIBLE SEALING MEANS MOUNTED ON SAID CONTAINER, AND MEANS ACTUATED BY SAID DISPLACING MEANS WHEN SAID TREATING AGENT HAS BEEN SUBSTANTIALLY COMPLETELY DISCHARGED FROM SAID CHAMBER TO PRODUCE EXPANSION OF SAID SEALING MEANS AGAINST THE INNER WALL OF SAID TUBINS WHEN SAID TREATING AGENT HAS BEEN SUBSTANTIALLY COMPLETELY DISCHARGE FROM SAID CHAMBER, WHEREBY A PRESSURE DIFFERENTIAL IS PRO-