US2823620A - Method and apparatus for starting flow of wells - Google Patents

Description

Feb. 18, 1958 `c. c. CARLISLE 2,823,620

METHOD AND APPARATUS Fon STARTING FLOW oF WELLS Filed Sept. 6, 1952 2 Sheets-Sheet l n I. Il

l. l' /I b- Trae/vifs Feb. 18, 1958 c. c. CARLISLE METHOD AND IPPARATUS FOR STARTING FLOW OF WELLS Filed Sept. 6, 1952 2 Sheets-Sheerl 2 ATTOP/VYS United States Patent METHOD AND APPARATUS FOR STARTING FLOW 0F WELLS Charles C. Carlisle, Tulsa, Okla.

Application September 6, 1952, Serial No. 308,236

6 Claims. (Cl. 10S- 232) This invention relates to an apparatus for flowing wells by the gas lift method and more particularly to a method of'starting oil ow in vsuch vwells after the gas pressure has failed or the wells have been shut down. For example, an oil well often flows when it is first drilled in under the formation pressure but after a short time the gas which produces the flow drops in both pressure and volume below that required to maintain the oil flow. When that state is reached, a gas may be injected into the oil near the bottom of the well under artificial pressure and the ow may be maintained. However, when once the flow is started, the gas must be supplied in a continuous stream, for if the supply is even momentarily interrupted the oil flow will cease and the well must be restarted.

In starting flow of a well it is difi'icult toovercorne the excessive hydrostatic head of oil which ordinarily accumulates in such wells during interruption of the gas supply or shut down periods, because such excessive hydrostatic head cannot be removed by direct application of a reasonable gas pressure. For example, in the more common type of gas lift, the gas is passed into a well containing a casing and a flow tubing in such a manner that the gas passes around the lower end of the flow tubing in a stream and in its passage gasifies the oil as it is started upwardly by the induced pressure in the well whether through the casing or through the tubing depending upon the passage through which the gas is injected. Such methods operate effectively and efficiently with a minimum pressure of gas aslong as the well is under flow but when the ow is shut down a vrelatively greater hydrostatic head of well liquid accumulates and rises above Ythe point of gas discharge. Thisfhigh head of ungasified liquid cannot be overcome by a steady application of gas under moderate flow pressure in a continuous direction. This difficulty arises because when pressure of the gas is applied to depress the liquid level in one flow passageway, the hydrostatic head is pushed higher in the other ow passageway and forces the liquid back into. the .producing formation until the oil volume in the well be .decreased until its hydrostatic pressure head be reduced to a state below thatof the injected gas pressure so that this artificially suppliedgas can be forced downward and underneath the tubing into the oil column, at that point, into the oil column in the other ow pas-l sageway. Any attempt to directly start the well by straight application of gas pressure in order to force over the entire excess load of accumulated oil and uncoverv theA lower end of the tubing increases the hydrostatic head until it reaches the maximum, that is, until itis equal to the entire height of the flow passage which may bek several thousand feet. It, therefore, is obvious that the required starting pressure must be at least equalV to the lished such equipment would not be needed andcould not be economically operated in maintaining normal flow pressure. To overcome this difficulty it has been proposed to start flow from deep wells by a rockover method by which a series of impulses is effected in alternate directions through the respective passageways by alternately applying pressure to one passageway to depress the liquid level in that passageway and to raise the level in the other passageway. These impulses when properly timed cause the liquid to raise higher in one passageway and higher until the rising column is eventually forced out of the top of the well, the action being assisted by the gas which has been absorbed under the pressure produced by the agitation resulting from the alternating or rocking movement. However, it is difficult to manipulate the numerous Valves that are required to properly time the impulses.

total ,hydrostatic head developed in the flow passageway, 'Y

It is also apparent that. after ow'has beenrestaba discharged from the well.

Therefore it is the purpose of the present invention to provide a simple method and apparatus for starting flow by maintaining the rising and falling columns under proper movement and timing to quickly and effectively establish a continuous fiow in one direction.

In accomplishing this and other objects of the invention hereinafter pointed out, I have provided improved structure, the preferred forms of which are illustrated in the accompanying drawings wherein:

Fig. l is an elevational view of a gas lift well equipped with a flow starting apparatus constructed and arranged in accordance with the present invention.

Fig. 2 is an enlarged section through the single control valve showing position of the valve for establishingilow of gas pressure in one passageway and release of pressure through the other passageway.

Fig. 3 is a similar view showing the control valve in position to conserve pressure through transfer gas pressure above the respective columns from one flow passageway to the other prior to application of the gas pressure supply.

Fig. 4 is a similar view showing the control valve in position for applying pressure through the second passageway and releasing pressure from the first passageway.

Fig. 5 is an axial section through the valve on the line 5--5 of Fig. 4.

. Fig. 6 is yan elevational view of a modified form of starting apparatus employing discharge ducts separate from the flow starting ducts. v

Fig. 7 is a sectional view through the control valve used in the modified form of apparatus.

Fig. 8 is a sectional view of a control valve similar to the control valve illustrated in Fig. 2 and which may be used in the modified form of apparatus.

Referring more in Adetail to the drawings:

1 designates a well extending from the surface of the ground indicated at 2, to a liquid accumulating pocket 3 formed in a liquid producing formation 4. The Well 2 is provided with a casing 5 that is shown as extending from the producing formation to a point above the surface of the ground where it is provided with a casing head 6 having lateral connections 7 connected with a flow pipe 8. Extending through a seal 9 carried by the casing head vand depending into the well casing is a flow tubing 10 which connects through its lower end 11 with the interior of the casing 5 at a point in submergence by a column of well liquid that is forced upwardly into the casing and tubing under normal formation or rock pressure. It is thus obvious that two flow passageways are provided, one through the ow tubing 10 and the other through the annular space 12 between the tubing and casing so that either one or the other of the passageways may be utilized for the introduction of a Igaseous pressure medium and the other asaow passageway through which well liquid is In carrying out the present invention for beginning of a flow of the well liquid through one of the passageways, the upper end of the tubing 16 and pipe 3 are connected by branch pipes 13 and 14 with a control valve 15. Also connected with the control valve is a gas supply pipe 16 by which gas is alternately admitted under pressure to pipes 13 and 14. Also connected with the valve is a liquid discharge pipe 17 for conducting the well liquid to a place of storage.

Located in the respective pipes adjacent the various connections with the valve 1S are gauges 15, if: and 2i, which register pressure admitted through shutoff valves 22, 23, 24 and 2S respectively. The control valve 1S includes a valve body 26 having circumfercntially disposed radial branches 27, 2S, 29 and 30 that are adapted to be connected with the pipes 16, 14, 17 and 13 respectively. Extending transversely through the valve body is a conical bore 31 in which is rotatably mounted a tapered valve plug 32 that is adapted to be drawn into seal tight relation with the bore by means of a nut that is applied to a reduced threaded end 34 at the smaller end of the valve plug and which bears against the washer 35 that seats upon a shoulder 36 encircling the smaller end of the bore as shown in Fig. 5. The opposite end of the valve plug has a reduced terminal 37 to which is attached a handle 38 by which the valves may be turned through three positions as later described.

As above stated, the normal formation pressure will cause the well liquid to raise upwardly within the lower end of the tubing 10 and casing 5 so that substantially high hydrostatic heads `are carried within the well wherever the flow is shut down. When the well is flowing a gas under pressure is ordinarily admitted through the tubing 1t? and discharged across the lower end 11 thereof 'for upward relief through the annular passageway 12 in such a manner that the gas intermixes with the liquid in the casing and reduces the head thereof. so that the liquid ilows upwardly through the casing and is discharged by way of the casing head or if desired, the gas pressure may be applied by way of the passageway between the casing and tubing and the intermiXed fluids are discharged by way of the tubing. When the liow has 'been shut down as when making repair to the equipment or as may be required in pro-rationing the production of a pro ducing area, relatively great hydrostatic heads of liquid accumulate in the well hole so that the level stands a material distance above the outlet end 13 of the tubing. Consequently, it is necessary to rst overcome this head before tlow can be established from the well by means of a reasonable gas pressure. As preivously stated, this might be effected by introducing through the well tubing or casing gas under sullicient high pressure to effect depression of the liquid, for example, in the casing and lift a column of liquid the entire height of the tubing, but, as previously stated, it is not practical to supply such high pressure and l have overcome this `difficulty by employing an improved rockover `method whereby gas under reasonable pressure is alternately admitted through the casing and tubing by means of the single control valve 26 through its various positions illustrated in Figs. 2 to 4 inclusive.

As shown in Figs. 2, 3 and 4, the plug member of the valve is provided with laterally disposed arcuate ports 39 and 40 having the terminals spaced apart around the periphery of the plug and 'from each other corresponding with the spacing of radial channels 41 that are provided in the valve body to connect with the pipes 13, 14, 16 and 17. The valve core is also provided intermediate the arcuate ports with a diametrical port 42 that is adapted to connect diametrically opposite pipes 13 and 14 when the terminals of the arcuate ports are moved out of connection with the pipes 16 and 17 as shown in Fig. 3.

Assuming that the starting operation begins with seating of the valve plug in the position shown in Fig. 2 where the port 39 interconnects the pipes 14 and 16 and the arcuate port 40 connects the pipes 13 and 17, gas

Clt

under pressure 4is then discharged from the pipe 16 through the arcuate port 39 and pipe 14 into and through the passageway 12.

In this position of the valve plug, the tubing 10 is vented through the port 40 to the pipe 17. Pressure is then built up in the passageway 12 from the supply pipe 16 to the available maximum pressure causing the liquid level to be depressed therein and the liquid level to rise in the tubing 19 to a point as high as possible or until the hydrostatic head of liquid in the tubing 10 equalizes the applied pressure in the passageway 12. Under these conditions some liquid may be forced back into the formation, thus further lowering the liquid level in the casing. When a substantial equilibrium is obtained between the pressure in the passageway and the hydrostatic head in the tubing, the valve core is turned to the position shown in Fig. 3. The gas pressure in the passageway 12 is then transfered through the pipe 13, port 42 and pipe 14 into the tubing. This conserves a portion of the gas under pressure in lthe passageway 12 and reduces the amount of gas to be injected into the tubing 10 on the next cycle. This position of the valve is substantially momentary, the time being determined upon inspection of the pressures indicated on the gauges 19 and 20. As soon as the indicated gas pressures are substantially equalized, the valve core is moved to the position shown in Fig. 4 where the port 4i) connects the pipe 14 with the discharge pipe 17 and the port 39 connects the gas supply pipe 16 with the tubing 10. The gas in the passageway 12 is then released through the discharge tube 17 and the full gas pressure is applied through the tubing 10 to follow up gravity descent of the liquid lcolumn and thereby take advantage of the momentum and effecting elevation of the liquid in the passageway 12 to as high a level as possible and depression of the level in the tubing to as low a point as possible. These points having been reached, the valve core is returned to the position shown in Fig. 3 where the high pressure in the tubing 10 is transferred in part to the passageway 12. When the pressures are substantially equalized the valve core is turned to the position shown in Fig. 2 whereby the gas under pressure is again applied through the passageway 12 and pressure is vented from the tubing 10 through the discharge pipe 17, the momentum of the moving liquid again being relied upon to assist the depressing of the liquid column as far as possible and raise the column in the tubing. This alternate application of gas under pressure on one side with released pressure on the other side, is repeated as often as necessary and the liquid columns are thereby caused to surge back and forth in conjunction with the inuences of gravity and momentum whereby an appreciable amount of agitation is produced and contact of the liquid with the gas is increased with a resultant increase in gas absorption, which absorption, of course, is materially assisted by the pressure under which the gas is introduced. The gravity descent of one of the columns of liquid eventually reaches the end 11 of the tubing 10, for example, should the pressure in the tubing 10 depress the column below the end 11, the gas will break through under the end of the tubing into the passageway 12 and if the column in the passageway 12 is depressed to the end of the tubing, the gas will break through into the column of liquid carried by the tubing 10. This breaking through of the gas under pressure effects atomization of the liquid in the higher column to eiect elevation thereof to the top of the well and discharge through the pipe 17.

All of the alternate pressure applications are easily and properly timed by the single control valve at intervals to correspond with the beginning of the descent of the respective liquid columns, this timing being determined by watching the pressure gauges. The result is that the columns are caused not only to surge back and forth but also to rise higher and higher on the respective sides until a quantity of the liquid is sent over. It is important that this rocking or surging motion be so timed as to obtain the maximum surge with the geratest possible rapidity, since such timing results in taking the great advantage of the momentum of the moving liquid columns. In this fashion the combined inuence of such momentum of the liquid bodies, together with the pressure under which the gas is introduced and the expansive influences of the absorbed gas, eventually result in establishing continuous ow from the Well.

In the present invention the single control Vvalve facilitates this timing and assures that the application of gas pressure is applied at the right moment whereby the ow is started with a minimum of cycles and in a shorter time period and with less gas.

In the form of the invention shown in Fig. 6, the passageway 43 between the casing 44 and tubing 45 is connected through the casing head 46 with the main ow discharge pipe Y47 having a shutoff valve 49 located therein in spaced realtion with the casing head 46. The tubing 45 extends through'lthe casing head 46 and is connected by a ow discharge pipe `50 of similar capacity with the pipe 47 through a tting 51. The pipe 50 is provided with a shutoifvalve 52 that is spaced above the casing head. In this form of the invention a gas pressure control valve 53 may be provided which does not employ a diametrical passageway 42 intermediate the arcuate ports 54 and 55 of the valve core 56. The valve 53 has four branches 57, 58, 59 and 60 similar to the valve previously described. The branch 58 constitutes the gas pressure inlet and is connected with the gas pressure supply through a pipe 61. The branch 57 is connected with the tubing through a pipe 62 while the branch 59 is connected with the pipe 47 by a pipe 63, the connections of the pipe 62 and 63 being made intermediate the casing head and the valves 49 and 52. The branch 61 is connected by a vent pipe 64 with the discharge pipe 47 on the discharge sides of the valves 49 and 52.

In this form ofthe invention, Vpressure is equalized between the tubing 45 and passageway 43 surrounding the tubing through a bypass pipe 65 that connects the pipe 63 with the tubingS. i The bypass is provided with a shutoi valve 66. A pressure gauge 67 is connected in K the gas pressure supply line to indicate the supply pressure. Similar gauges 68 are connected into the bypass 65 on the side of the valve 66 adjacent the pipe 63 to register the pressure in the passageway 43. A pressure gauge 69 is also connected in the pipe 62 to indicate the pressure in the tubing. A gauge 70 is also connected on the vent side of the valves to indicate the discharge pressure.

In this form of the invention ow is started with the valves 49 and 52 closed. The bypass valve 66 is also closed and assuming that the core of the control valve is set to connect the pipes 61 and 63, gas is discharged under pressure into the passageway 43 to depress the liquid level therein and raise the liquid level in the tubing 45. As soon as the gas pressure equalizes the hydrostatic head of liquid as indicated by comparison of gauges 68 and 69, the control valve is closed by shifting the core to a position Where the ports 54 and 55 therein are out of register with the branch connections. The valve 66 is then opened to allow passage of gas under pressure from the passageway 43 into the upper end of the tubing 45. As soon as the gas pressure is equalized the valve 66 is closed and the control valve 53 is moved to its other position where the supply of gas is discharged from the pipe 61 through the pipe 62 into the tubing 45 and the space 43 surrounding the tubing is vented through the pipes 63 and 64. The position of the valve core 56 is thus alternated in conjunction with opening and closing of the valve 66 to effect rocking of the columns of uid until a flow is established through the tubing 45 or pas- 6 sageway 4 3 as desired; vWhen the initial flow is started to the discharge line through the pipe 62 or 63 and onward through pipe 64, the valve 49 or 52 is opened to establish subsequent flow -in bypassing relation with the control valve. For example, if flow is started through the tubing 45, the valve 52 will be opened so that the main flow is from the tubing through the discharge pipe 50. If ow is to be established through the passageway 43, then the valve 49 will be opened and the ow is discharged directly to the pipe 47. Otherwise the operation is the same as described in the rst form of the invention. If desired, the bypass 65 may be omitted and a control valve 71 provided with a diametrical port 72 as shown in Fig. 8 whereby the operation will be the same as described in the rst form of the invention with the exception ,that the main flow would not be carried on through the starting valve. y

From the foregoing it is obvious thatvI have provided a simple arrangement to facilitate timing of application of pressure iluid to the respective columns of liquid so that pressures may be applied at the right time and thereby reduce thetime and pressure medium required in starting the ow of a well.

What I claim and desire to secure by Letters Patent is:

l. An yapparatus for starting flow of a well under gas pressure including ducts extending into the well from the top andhaving terminals submerged in liquid* contained in the well, oneof which is adapted to serve as a conductor of well uid from the well and the other a con ductor for the gas pressure into the well, a gas pressure supply duct, a well liquid discharge duct, control means having connections with all of said ducts at the top of the well for alternately establishing flow of pressure uid into one and then lthe otherof the well ducts and to release pressure through the discharge ducts for lgasifying co1- umns of the well liquid in said ducts until one of said columns is elevated to the discharge duct, and valved means connecting said well flow ducts for utilizing pressure in one well duct to initially repressure the other duct when said other duct is connected with the discharge duct.

2. An apparatus for starting ow of a well under gas pressure including ducts extending into the well from the top lof the well and terminating in submergence by liquid in the well, one of said ducts being adapted to serve as a conductor of well liquid from the well and the other a conductor for the gas pressure into the well, a gas pressure supply duct, a well liquid discharge duct, a single control valve having connections with said ducts at the top of the well and having a valving element provided with ports arranged relatively to said connections and having positions to alternately establish flow of pressure liquid into one and then the other of the well ducts and to release pressure through the discharge duct when the valving element is shifted through said positions, said valving element having a port 'adapted to interconnect said well ducts intermediate said positions of the valving element to utilize pressure in one well duct for initially pressuring the other well duct, and gauges connected with the respective ducts near said connections with the control valve.

3. The method of starting flow of well liquid in a well in which flow is maintained by introducing a pressure fluid medium from a source of supply through one duct to effect upward llow of well uid through another duct with the ducts extending from above ground into the well and terminating below the liquid in the well, said method of starting the ilow comprising passing a fluid pressure medium through one duct to depress well liquid in the said one duct and elect upward How of well liquid in the said other duct until the pressure in said one duct and the hydro-static head of liquid in said other duct substantially balance, shutting oit the source of pressure uid medium, transferring pressure fluid medium from said one duct into said other duct for conserving the pressure fluid medium and whereby the well uid drops in said other duct and raises in said one duct, supplying the uid pressure medium from the source of supply through the said other duct and simultaneously releasing the pressure from said one duct to enhance the momentum of the rise and fall of well liquid in said ducts and increase the rise of Well liquid in the said one duct, shutting off the source of pressure uid medium, transferring the pressure iluid medium from the said other duct into the said one duct, and continuing said steps in successive order to effect an increasing rocking movement of the well liquid downwardly in one duct and upwardly in the other in increasing momentum until the Well liquid ows from the Wel 4. An apparatus for starting flow of a well under uid pressure including ducts extending into the well from the top of said well and terminating in submergence with liquid in the well, one of said ducts being adapted to serve as a conductor of well liquid from the well and the other a conductor for the pressure uid into the well, a pressure liuid supply duct, a Well liquid discharge duct, a control valve, means for interconnecting all of said ducts at the top of the well with said control valve, said control valve having a valving element provided with ports arranged relatively to said connections and having positions to alternately establish ow of pressure uid into one and then the other of the well ducts and to release pressure through the discharge duct when the valving element is shifted through said positions, said valving element also having a port adapted to interconnect with said well ducts intermediate said positions of the valving element to utilize pressure uid in one well duct for initially pressuring the other well duct.

5. An apparatus for starting ow of uid from a well under gas pressure including ducts extending from the top of the Well and terminating within the uid of said well, a discharge duct connected with each of the well ducts at the top of the well, a shutoi valve in each of said discharge ducts, a gas pressure supply duct, branch ducts connected with said discharge ducts on inlet sides of the shutoff valves, a single control valve interconnecting the branch ducts with the gas pressure supply duct and having a valving element provided with ports arranged relatively to said connections of the supply and branch ducts and having positionsto alternately establish ow of gas pressure into one and then the other of the well ducts and to release gas pressure from the discharge ducts when the valving element is shiftedthrough said positions forv eiecting alternate pulsations on the Well iluid until flow is established to the top of the well through one of the well ducts to the discharge duct which is connected therewith, said shutoff Valve in that discharge duct being adapted to be opened to discharge said ow of well fluid, and said valving element also having a port for establishing connection between the well ducts intermediate said positions of the valving element for equalizing pressure in'said ducts.

6. An apparatus for starting flow of uid from a well under gas .pressure including ducts extending downwardly from the top of the well ,andl terminating within the well uid of s'aid well, main discharge ducts connected with the Well ducts at the top of the well, shutoi valves in each of the discharge ducts, -a gas pressure supply duct, branch ducts connected with the well ducts on inlet sides of the shutoi valves, a single control valve interconnecting the branch ducts and the gas pressure supply duct and having a lvalving element provided with ports arranged relatively to said connections with the branch ducts and having positions to alternately establish flow of gas pressure into one and then the other of the well ducts and to release pressure when the valving element is shifted through said positions for eiecting alternate pulsations on the well liquid until flow is established to the top of the well through one of the well ducts, said shutoff valve in that Well duct being adapted to be opened to pass said ow of Well liquid through the discharge duct, and a valved bypass interconnecting said well ducts at a point on the well side of the shutoi valves for equalizing pressure in said well ducts between operations of the control valve.

References Cited in the le of this patent UNITED STATES PATENTS 1,740,105 Lake Dec. 17, 1929 1,827,925 Wolcott Oct. 20, 1931 2,134,200 Pivoto Oct. 25, 1938 2,340,481 Lloyd Feb. l, 1944

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