US2275947A - Gas lift - Google Patents

Description

March 10, 1942. M CQURTNEY 2,275,947

GAS LIFT Filed May 27, 1941 2 Sheets-Sheet l March l0, 1942. 1 M, COURTNEY 2,275,947

GAS LIFT Filed May 27, 1941 2 Sheets-Sheet 2 www Patented Mar. 10, 1942 UNITED STATES PATENT OFFICE `uns HFT John M. Courtney, Vivian, La.y

Application May 27,1941, Serial No. 395,327

(Ci. s- 232) 4 Claims.

This invention relates to an apparatus for flowing or pumping a Well in which there is not sufcient formation pressure for the well to flow by A itself. Itis particularly applicable to deep wells such as oil-wells but the principles can be applied to shallow wells or to wells from which uids other than oil are to be withdrawn. It can also be Yapplied to aid the natural flow from wells which have sucient formation pressure to flow by themselves but in which it is. desirable to increase the rate of flow.A

The common practice in oil wells is to permit them to iiow under their own natural pressure as long as they will do so and then to `apply a mechanical reciprocating pump to complete the removal ofthe oil. While this is the method that' is at present in general use it is a cumbersome unsatisfactory method. Because suction will only raise oil for a distance of some 35 feet it is necessary to have the pump near the bottom of the well so that it can exert pressure instead of suction on the column of oil coming out of the well. 'I his involves the use of pump rods of lengths of 5000 feet `or greater in many instances and when the pumpvplungcr or the valves become worn it is necessary to remove the pump from that depth to replace the worn parts.v Furthermore, the collars onthe pump rod wear rapidly and all the pump parts do likewise because of the small particles of grit that remain in the oil andthe whole device is mechanically ineicient because of the relatively lcng pump rods that must be reciprccated to perform the pumping operation.

As an alternative to the use of reciprocating mechanical pumps, gas lifts of various kinds have been proposed. None, up to the present time, however, have been very successful because none were so arranged as to avoid'erosicn and plugging, nor were they in most .instances efficient enough to lift a sufiicient amount of oil with a sufficiently small expenditure of energy in operation. Y The present invention is directed to a gas lift type of pumping apparatus'but diers from previous devicesl of this type in that itis arranged so that the gas pressureis never on the formation from which oil is being pumped, sothat the possibility of clogging or plugging is substa/ntially eliminated, so that the operation `of the device can be readily started without the necessity of extended swabbing of the pump tubing, so that the operation thereafter can be carried on efflciently-with a minimum of4 gas, as compared to the amount of oil lifted, so that the apparatus will not be injured by .the operation of a swab in the pump tubing, and so that the gas used in the pumping operation may be readily recovered and re-used.

Briefly, the apparatus of the present invention consists of a string of pump tubing which extends down to the formation to be pumped, a packer near the bottom of the string of tubing to seal the tubing to the well casing or wall, preferably alter or a perforated element below the packer to lter the oil that enters the pump tubing, a particular type of gas lift mechanism in the pump tubing above the packer and the necessary equipment on the surface for forcing gas down into the well-around the pump tubing, taking gas and oil from inside of the pump tubing at the surface, separating this gas and oil, and recom- .pressing the gas for further use. .A

The gas lift mechanism forms the lower end of the tubing string and includes a standing valve which permits oil ow upward in the tubing but eiectively prevents any flow of either oil or gas downward into the formation. Above this is a device which receives gas under pressure from outside of the pump tubing and directs .this gas upwardly Within the pump tubing so as to suck fluid from beneath it and blow any fluid above it upward and out of the well. This mechanism is of particularinterest because of its detailed construction which provides av ltering string, a series of metering orifices or choke buttons which limit the amount of gas that can passinto the tubing at any particular pressure and aA .series ef pressure valves that prevent gas from entering the pump tubing below a predetermined pressure andalso prevent oil from within thepump tubing from passing out through the gas lift mechanism into the casingoutside of the pump tubing; i 4

Incidentally, there are .several inlets for gas into the` pump tubing one or more of which are considerably larger than the others and are set for release only at a relatively high pressure so that if a relatively high pressure is placed on the'. gas going into the well these openings begin..

to function and allow a strong blast of gas to pass up the well thus clearing the well for subsequent cperation and a lower pressure. The metering valvesare so constructed that they do not readily become plugged with sediment and the pressure valves are so arranged that they protect the metering valves from sediment in the cil and atthe same time are not readily clogged.

or eroded themselves.

through a condenser and then into a storagev tank. .Liquid from the bottom of the settling tank passes to storage and' a oat valve arrangement controls the level of the liquid` in the settling tank so that it never gets low enough for gas to escape to the liquid storage. From the gas storage tank, gas is passed through a heater to a reducing valve and then into the well outside of the pump tubing. The heater at the reducing valve prevents the gas from freezing when its pressure is reduced.

Additional l"details and advantages of this invention will be apparent from the following detailed description of the preferred embodiment thereof 'but it is to be understood that the principles of this invention are'not limited .to that particular embodiment except as specified .in the claims.

In the drawings:

Figure 1 is a schematic view' partly in section of a preferred form of the apparatus of this invention;

Figure 2 is a sectional elevation view o f the gas Figure 3 is a top view of the gas lift; Figure 4 is a top sectional view of the gas lift taken on line 4-4 of Figure 2; and.

Figure 5 is a detail view showing one of the. ,valve cages.

As illustrated in Figure 1, the apparatus is arranged for pumping an oil well I which includes a, casing II which extends down to the top of a formation I2 from which oil is to be removed. Extending out of the lower end of the casing I I into the formation I2 is a perforated cup-shaped member I3 supported at the bottom of a string of pump tubing I4. Oil from the formation and of course water, gas or any other fluids that are in the formation, enter through the perforated member I3 and pass upward through the pump tubing.

Just 'above' the perforated member I3 is a packer I which is shown only diagrammatically since packers are old inthe art. This packer serves to seal the outside of the pump tubing to the inside of the casing so that there will be no communication from the space between the pump tubing and the casing to the formation being pumped.

At some place in the pump tubing preferably below the gaslift, is a standing valve I6 which vertical opening 23 in the body member.

ample, the three smaller openings may open at a pressure of around fifteen pounds per square inchand the one larger opening may open at around seven hundred pounds per Square inch. The larger opening has preferablylat least from ten to twenty times the capacity of the smaller openings, however, so that when it does open a large volume of gas flows through it.

The openings I9, 20, 2I and 22 are formed by vertical openings 23, extending from the top of the main body element 24 of the gas lift, well down into its mid section Where they intersect openings 25 extendingy radially inward from the outer periphery of the body member. In order. to accurately govern the flow of gas through these openings, a metering orifice 'member or choke button 26 is screwed into each -of these openings. A recess 21 is provided in the body member 24 for each of these metering orice .members so that the head does not extend outward beyond the periphery of the body member.

Each of these metering members 26 has a longitudinal opening 28 and a transverse'intersecting opening 29 through whichA gas may enter the Since these openings may be accurately drilled to size they provide a means for accurately controlling the amount of, gas which enters the opening at any particular pressure. -It may be noted inligure 2 that the opening in the metering member which supplies the large opening 22 is considerably larger than the opening in the member opposite it which supplies one of the smaller openings I9. By providing the intersecting transverse opening 29 the possibility of plugging of the metering members is greatly reduced.-

Around the body member 24 of the gas lift is a perforated metal screen 30 which covers the metering membersand prevents, tol a large extent, the entrance of foreign. materials that might plug the metering orifices. I

At the outlet ends of the various gas openings I9, 20, 2I and 22are spring pressed ball valves each covered by a cage 3I. Each of the balls -32 rests in a seat formed in the bodyv member 24 and is pressed downwardly Iby a spring, 33` and is no more than a check valve to prevent downward flow of nuid in the pump tubing. Above this in the pump tubing string is the gas lift I1 34 which is held in place by a. valve cage 3|. The valve cages 3| are so constructed that although they hold the springs in place, gas which passes upward past the'balls 32 is not hindered to any great extent in its upward and outward flow and is able to Asweep on up the pump tubing and carry withit any oil, water, gas orr otherfluid that comes up through theopening I8 in the body member. It will be noted from Figure 2 that the valve spring 34 on the valve for the larger opening 22 is larger than the spring'on the valve for the smaller opening I9 and it should bementioned that this spring is stronger so that it holds the valve closed except under a much higher pressure.

Above the gas' lift is a constriction 36 in the pump tubing which constriction prevents a swab, if used, from passing. down and strikingls the valves in the gas lift.

At the surface of thefground is the usual Christmas treevalve" 3l with a gauge 38 which l indicates the pressure of the gas between the pump tubing and the casing and a gauge 39 which indicates the pressure of the fluds in the pump tubing. Gas is supplied to the 4space between the pump tubing and the casing from a gas storage tank 39 through a heater 40 Iwhich prevents the'gas from freezing when the pressure on it is reduced, and then through a reducing valve 4|. A gauge 42 is provided just beyond the reducing valve to determine the pressure of the gas at that point and a control valve 43 is provided between the reducing valve and the well to control the entrance of the gas into the well.

As the fluid comes out of the pump tubing it in a condenser 5l and returned tothe gas stor-- age tank 38.

The liquid from the separator 68 is drawn off through a pipe 52 under the control of valve 53 and sent to storage tanks for further use. The valve 53 is controlled Vby a float in the separator 48. This avoids the possibility of the liquid level in the separator becoming so low that gas passes to the liquid. receptacle.

A careful. inspection of the arrangement of parts in the device described and particularly in the gas lift itself will reveal the fact that there is no place where sedimentA from the oil or other uid being pumped can readily settle ifuto the valves or meteringorices and thus cause mis` functioning ora failure to function of the device. In some instances in starting the operation o@ the device it will be desirable to clean out the.

pump tubing but this is seldom necessary. Ordinarily, it will only be necessary to raise the pressure between the casing and the pump tubing to such a point thatgthe highv pressure valve opens and this will immediately blow the pump tubing free of excess oil and start the operation ofthe device. Thereafter the pressure can be reduced 1 to a point where the high pressure valve closes,

A of said tube to the inside of the well at a point near its lower end, means to force gas under pressure into the space between the outside ofv the tube andthe inside of the well 'above the sealing means, and means to inject into thetube -in such a manner as to create an upward flow therein, the gas from outside of saidtube, the

improvement that comprises in the means to inject the gas into the tube. a plurality of metering orifices for controlling the rate gf ilow oi gas into the tube and a pressure sensitive check valve positioned between each metering orifice and the interior of the tube to prevent outward ow from lthe interior of the tube, at least one of said metering orices being larger than at' least one other of said metering oriiices and the check valve for the larger orifice being biased so as to remain lclosed except at a relatively high differential pressure.

2.\In a gas lift pumping device for use in a well and comprising a tube adapted to be lowered into fluid in a well, means to seal the outside of said tube tothe inside of the well at a point near its lower end, means to force gas under pressure into the space between the outside of the tube and the inside of the well above the sealing means, and means to inject into the tube in such a manner as tocreate an upward-flow therein, the gas from outside of said tube, the'irnprovement that comprises as the means to inject' the gas into the tube, a cylindrical body member'having a central'longitudinal opening therethrough, through which uid may pass upward, a plurality of longitudinal openings arranged around the rst mentioned opening and extending from the top downward only partly through said body member, an opening from each of the second mentioned longitudinal openings extending radially to the outside of said body member, a' sup'- plemental member having a metering oriice therein positioned in each of said radial openings, a pressure sensitive check valve at the upper end of each of the second mentioned longitudinal openings, means connecting a tubing to the lower end of said cylindrical member so that it willr be in communication with the central opening at the bottom of the cylindrical member and means connecting the top of the cylindrical member with a section of tubing so thatI the interior o! that section of tubing will be in communication with the' upper end of all of the longitudinal openings.

`3. In a gas lift pumping device as definedI in claim 2 the additional improvement that comprises .having the check valves so arranged that each check valve comprises a ball, a spring `pressing said ball downwardly against a. seat formed in the top of one of the second mentiened longitudinal openings and a cage for holding the ball and the spring which cage is so con- .str'ucted as 'to direct the ow'of gas outward and upward from the second mentioned longitudinal opening. e

4. In a gas lift pumping device as rdened in claim 2 the additional improvementI that comprises a check valve in the tubing below the body member to. prevent vthe downward 'ow of fluid therein.

JOHN M. co'URTNEY. i

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