US2348564A - Well device - Google Patents

Description

May 9, 1944. H; c. ons 2,348,564

WELL DEVICE H. C. OTIS WELL DEVICE `May 9, 1944.

Filed Aug. 2 1940 2 Sheets-Sheet 2 Patented May. 9,

UNITED STATES PATENT OFFICE WELL DEVICE Herbert C. Otis, Dallas, Tex. Application August 2, 1940, Serial No. 349,773

(Cl. s- 232) 18 Claims.

This invention relates to new and useful improvements in well devices.

One object of the invention is to provide an improved control device for use in flowing wells, which is arranged to permit an upward, flow of the well iluids so long as the gas in said fluids is lifting or raising the oil; said device being constructed to substantially shut ,olf upward flow to retard the production or/ilow of gas alone when such gas enters the production string, whereby the gas in the producing formation is conserved and is permitted to ilow to the surface in appreciable volumes only when it is acting to raise the oil.

Another object of the present invention is to provide an improved well device for controlling the upward flow of well fluids through the production string in accordance with the rate of entry of the well uids from the producing formation into the bore, whereby a liquid seal is at all times maintained around the inlet of the production string and the gas in the producing formation is conserved.

An important object of the invention is to provide an `improved well device which operates as an intermitter and which is constructed so as to permit maximum eflicient flow upwardly through the producion string until such time as the liquid level in the well bore falls to a predetermined point, at which time said device closes to retard the flow to maintatin a liquid seal around the production string inlet; the device reopening to again permit iiow under predetermined well conditions.

Another object of the invention is to provide a well device, of the character described, which is automatically operated by the pressure differential thereacrossand which is readily adjustable so as to beactuated by predetermined pressure differentials said device being so constructed that, if desired, it may be run into and removed from the well by means of a flexible line or cable.

A particular object of the invention is to provide an improved well device for controlling the upward flow of well iluids through a production string, said device including a main ow passage having a valve element, which is actuated by the pressure differential therewith and also having a minimum flow orince above the valve element, whereby a flow may occur through the minimum flow orifice to control the actuation of the valve element.

A further object of the invention is to provide an improved control device, of the character dethereacross, y associated scribed, wherein the minimum 4flow orice establishes communication between the well casing and the well tubing above the valve element, whereby when the liquid level in the casing falls to a predetermined point, gas is admitted to the tubing to lighten the liquid column therein and permit closing of said valve; the location or elevation of the minimum flow orifice being subject to variation, whereby the liquid level in the casing may be maintained at a predetermined point, in accordance with the location of said orifice.

Still another object of the invention is to provide an improved well device, of the character described, which may be connected with a suitable removable locking tool so that it may be removably supported at any desired elevation in the production string or which may be directly coupled in the production string and lowered therewith into the Well bore.

A A construction designed to carry out the invention will be hereinafter described, together with other features of the invention.

'Ihe invention will be more readily understood from a reading of the following specication and by reference to the accompanying drawings, in which an example of the invention is shown, and

wherein:

Figure l is a transverse, vertical, sectional view of a well deviceconstructed in accordance with the invention and illustrating the same mounted on the lower end of a running and locking assembly, which supports the device within the well tubing,

Figure 2 is an enlarged, transverse, vertical, sectional view of the device, showing the valve element in its closed position,

Figures 3 to 5 are horizontal, cross sectional views, taken on the lines 3 3, 4 4 ad 5 5 rerespectively, of Figure 2,

Figure 6 is a view similar to Figure 1 showing a modiiied form of the invention with the valve element in its open position,

Figure '7 is an enlarged, transverse, vertical, sectional View of this form, with the valve element in its closed position, and

Figure 8 is a horizontal, cross-sectional view, taken on the line 8-8 of Figure 7.

VIn the drawings, the numeral I0 designates a tubular -body or cage which is formed with an axial bore H extending entirely therethrough. The lower portion of the bore is enlarged as shown at I2, and above.this enlarged portion the bore is reduced in diameter to provide a reduced passage I3. The annular shoulder i4 which is formed between the reduced passage I3 and the enlarged lower portion I2 of the bore is inclined or bevelled to form an annular inclined valve seat.v A guide block I5 has its upper portion threaded into the lower enlarged end I2 of the bore of the body or cage Ill and this block is provided with an external shoulder I6. When the guide block is screwed upwardly into the body or cage, a suitable packing gasket or ring I1 is interposed between the shoulder I6 and the lower end of the body so as to seal the connection between the parts.

The guide block I5 is formed with an axial bore or opening I8 and a plurality of flow passages I9 surround the bore and extend vertically through the block I5, whereby a flow of fluid from below the block may pass upwardly through these passages and into the enlarged lower portion I2 of the bore of the body or cage I0. From the enlarged lower portion of the bore, the iluid may pass the valve seat I4 and then flow upwardly through the reduced passage I3 in the body.

For controlling the flow oflluid through the reduced passage I3, a valve element is provided. This valve element includes an enlarged valve head 2| which has its upper portion rounded and adapted to engage the inclined or bevelled seat I4 within the body or cage I0. An elongate valve stem 22 which is preferably made integral with the valve head 2| and-which depends therefrom, extends downwardly through the axial bore I8 of the guide block I5 and this stem is slidable within said bore. The lower end of the stem extends a considerable distance below the block I5 and is provided with screw threads 23. For constantly urging the valve element downwardly so as to move the valve head 2l away from its seat I4, a coiled spring 24 surrounds said stem below the guide block. This spring has its upper end engaging the bottom of the guide block I5, while its lower end rests upon a flanged washer 25 which is sldable on the stem 22. The anged washer 25 is adjustably retained in position on the stem 22 by means of lock nuts 26 which are threaded onto the lower end of said stem. Manifestly, the coiled spring exerts its pressure to constantly urge the valve element 20 toward a lower position, as shown in Figure 1 and the spring pressure may be readily varied by adjusting the anged washer 25 through the medium of the lock nut 26. The projecting lower end of the stem 22, together with the coiled spring 24 and its associate parts are enclosed by an elongate tubular sleeve or housing 21, which housing is provided with ports 28 in its side wall and with an axial port 29 in its bottom. The ports 28 and 29 are provided for the purpose of permitting an unrestricted flow from the exterior of said housing into the interior thereof. The upper end of the housing 21 may be suitably fastened to the guide block I5 but as illustrated, is threaded to the lower end thereof.

The assembly, as above described, is adapted to be lowered within the well tubing A, which tubing extends through the well casing B in the usual manner. The assembly may be lowered by any suitable means and in any suitable manner, but as shown in Figures 1 and 2, said device is connected to the lower end of a running and locking tool T. This tool is fully disclosed and described in my Letters Patent No. 2,246,811, issued June 24, 1941, and provides a means whereby the valve assembly may be run into the tubing on a wire line and suitably supported within said tubing. Briefly, the running tool includes a tubular mandrel 30 which is provided with sealing cups 3l at its upper' end and similar sealing cups 32 at its lower end. The upper end of the valve -body or cage I0 ls adapted to be threaded onto the lower end of this mandrel.

The upper end of the mandrel is connected to the tubular mandrel 33 of a locking assembly. This assembly includes radially expanslble locking dogs 34 which'are suspended from a carrier or sleeve 35 slidable on the mandrel 33. Upward displacement of the carrier and locking. dogsfrom the mandrel 33 is prevented by an external annular shoulder 36 which is formed on the mandrel 33 and which is engaged by the dogs 34 when said dogs are moved upwardly relative to the mandrel.

The tool T also includes an elongate nipple or housing 31 which is connected in the tubing string A. This housing includes an annular recess 3Bl at its upper portion and said recess is provided with a shoulder 39 at its upper end. When the locking assembly is moved downwardly into the nipple, the locking dogs 34 are retracted so as to move into horizontal alinement with the recess 38. has entered the housing, the locking dogs 34 may move downwardly on the mandrel 33, whereby said dogs are` expanded radially outwardly, and upon an upward'movement of the assembly said dogs engage the shoulder 39 so as to prevent upward displacement of the entire assembly, as is clearly shown in Figure 1.

The housing 31 is formed with radiallyI extending inlet openings 40 which are disposed opposite the central portion of the mandrel 30, when the locking dogs are in their locking position, and these openings establish communication between the interior of the casing B and the annular space between the housing 31 and the mandrel 30 and between the sealing cups 3l and 32, whereby fluid may flow from the casing into this space surrounding the mandrel 30. The mandrel is formed with an inclined orifice 4I, which will be hereinafter referred to as a. minimum flow orifice and which serves to permit a reduced flow of uid into the bore of the mandrel 30. By observing Figure 1, it will be obvious that the bore of the mandrel 30 communicates with the bore I I of the valve body or cage I0 and also communicates with the bore of the mandrel 33 of the locking assembly. The upper end of the bore of the locking assembly mandrel is in direct communication with the bore of the tubing A. Therefore, an upward ow of fluid from the bore of the valve cage or body I0 may pass into the tubing string A.

In the operation of the device, the valve iis-- sembly is run into the well tubing A by means of the tool T and during the lowering of the apparatus, the surface connections or controls on the tubing are closed, whereby the well fluids are not flowing upwardlyV through said tubing. Of course, since the well is shut in, the liquid will be standing at a predetermined level, as controlled by well conditions, within the well casing A, which level is indicated by the dotted lines L in Figure 1. The housing 31, with which the running tool T coacts, is located below this standing liquid level of the well, whereby the valve assembly is disposed below such level when the tool T is locked Within the housing, as has been explained. As the device is being lowered through the well and after it is supported therein, but prior to the time that the surface con- After the locking assembly nections on the tubing are opened, the valve element 20 will be in its open or lowered position, as shown in Figure 1, being held in such position by the coiled spring 24. The pressures across said valve are of course,v equalized and said spring moves the valve element downwardly to its lowered or open position. When the sur-` face connections on the tubing are opened, an

upward flow of the well fluids will occur through the flow passages I 9 in the guide block I5 and upwardly through the reduced passage I3 of the valve body or cage I0. From this point, the well fluids liiow upwardly through the tubing string. There will also be a I'low from the interior of the casing through the ports 40 in the housing 3'I `and through the minimum flow orifice 4I of the mandrel 30, such uids admixing With the upWardly owing fluid in said mandrel.

It is contemplated that the combined flow area of the passages 19, together with the now through the minimum flow orifice 4I permit an upward flow through the tubing string which is greater than the flow of well fluid from the producing formation into the lower end of the well casing. This results in the well liquid being removed through the tubing string at a rate in excess of the rate at which the well fluids are entering the lower end of the casingv and therefore, the standing liquid level in the well casing will be lowered. Such loweringl of the liquid level in the casing B will be aided by the gashead or the trapped gas in the casing above such level.

The flow passages I9 in the valve guide I5 act somewhat as a choke because they restrict the flow to a certain extentl and therefore, when there is a flow through these passages, a pressure drop exists across fthem. However, it is noted that the restriction set upby the passages I9 is not sufcient to defeat aeration of the liquid bythe gas; that is, a suiiicient volume of iluid may pass through the passages I9 ,to assure that the velocity of the gas liberated from solution with the oil, together with the free gas, is at a rate sufficient to raise' the liquids upwardly through the tubing. while the weii/nuids are flowing upwardly through the flow passages and then through the tubing string, the pressure v drop across the passages I9 is not sulicient to cause the valve element 20 to move upwardly against the pressure of the spring 24l and therefore, during upward .now through said tubing, l

the valve 20 remains/in a'lowered or open position. The insuiciency of the pressure drop across the passages I9 is due to the low gas/oil the result that the Vpressure differential across the flow passages I9 will be increased. When the Valve is lowered, the lower portion of the head 2| of said valve is seated against the upper end of the bore I 8 of the guide I5 and therefore the pressure drop across the flow pasasges I9 is applied to the area of the valve stem 22, When the pressure differential across the passages is built up to a sufficient point due to the reduction in the weight of the liquid column, then the valve element is moved upwardly, against the pressure of the spring 24 and such upward movement causes the valve head 2I to engage the seat I4 and thereby shut off a further now upwardly through the valve body III and also through the flow passages I9.

After the valve is seated to close the flow through the bore I3, the only flow which can occur is through the minimum flow orifice-4I and, as has been explained, the area of this oriice is such that the flow passing therethrough is less than the flow of well fluid which is entering the bottom .of the casing B from the producing formation, whereby, the liquid level in the casing B will be again built up. Of course, gas

i will enter through the orifice 4I until the level of the liquid rises thereabove, after which liquid will now through said orifice. The orifice is of such small size that the volume of liquid passing therethrough is insuincient to liberate enough gas to produce the necessary velocity for lifting said liquid through the tubing and therefore, a liquid column yis built up within the tubing above the valve element. The valve element 20 will remain in its closed position until the column is built up within the tubing string to a point where the hydrostatic heador weight of said column is suilicient, along with the pressure of the spring 24, to again cause the valve to move downwardly to an open position, It is pointed out that if the diameter of the valve seat I4 is greater than that of the valve stem, the pressure which must be built up above the valve assembly must be greater than the pressure at which the valve closed because, as has been explained, when the valve is open, the effective area acted upon by the pressures is the area of the stern.

From the above, it will be seen that the valve is normally held open by the spring 24v to permit an upward flowthrough the tubing string A. This ilow is continued until the liquid level within the well casing falls to a predetermined point ,f and when such point is reached, the valve eleratio conditions of the column of fluid above the f valve assembly. Since the column above the valve assembly is 'predominately liquid, the A'columnv is relatively heavy and the weight thereof, plus the pressure of the spring 2,4, is sufcient to hold the valve open against the pressure yacting below the valve. /V i j When ow has continued throughl thai/device for a sufiicient length pf time vto lower the standing liquid level Within the casing A to a point below the openings 40 in the housing 3l,

, the gas which is trapped above the' liquid level in the casing will enter the openings 4Q and will then flow through the minimum flow orifice 4i and into the upwardly moving column of well fluid. The entrance of this gas into*` the liquid column will result in an aeration of the column,

whereby the weight of said column is reduced.'

As soon as this occurs, the pressure above the valve element will be reduced accordingly, with tion to shut oil the ow, such closure being effected by aeration of the column above the valve.

The valve remains in a closed position until the f liquid level has again built up within the well casing, after which the Valve opens to repeat the cycle. The valve is actuated by the pressure diierential thereacross and the provision of/the spring 24 which may be readily adjusted, makes the device practical under various well conditions. It is obvious that the gas head which is normally present in the upper end of the well casing is utilized to effect operation of thel valve to permit closing thereof. The, liquid level in the casing can never fall below the minimum flow orifice 4I yand therefore, a liquidy seal is constantly maintained around the tubing inlet. with thefresult that the escape or production of l gas alone, without oil, from the producing formation is retarded and substantially prevented.

Thus, the gas in the formation is conserved to prolong the life of the flowing well. The position of the minimum flow orifice 4| is subject to variation and the elevation of this flow orifice will effect the closure of the valve element at the desired, predetermined level of the liquid in the casing.

As above pointed out, the valve assembly may be lowered into the -well tubing by any suitable mean; and the invention is not to be limitedl to any particular type of running tool. In Figures 6 to 8 a slightly modified form of the invention, together with another type of running device is illustrated. In this form, the running tool R, includes an elongate tubular mandrel 50 which is provided with pressure seal packing elements on its lower portion. Above the packing cups, the mandrel has a slip expanding portion 52 which is arranged to coact with gripping slips 53 which are slidably mounted on the mandrel. The slips are carried by a suitable carrier or sleeve 54 and upward displacement of the carrier and slips is prevented by an external flange 55 which is formed on the mandrel. This tool is clearly sfown and described in my prior Patents Nos. Re. 20,546 and 1,972,791 and obviously, may be locked within the tubing at any elevation therein. When this type of tool is used, it is not necessary to provide the coacting nipple or housing 31 of the first form. l

The valve assembly of this form of the invention is substantially the same as the first form shown in Figures 1 to 5 with the exception that a valve body |00 is substituted for the valve body or cage I0. The body |00 has its upper end extended and this upper end is threaded onto the lower end 0f the mandrel 50 of the tool R. Below the internal screw threads at the upper end of the bore of the body |00, additional screw threads |0| are formed, whereby a valve retain-- ing collar |02 may be mounted within the upper ends of the bore of said body. A ball check valve |03 is confined below the retaining memier |02 and is adapted to engage an internal seat |04 which is formed at the upper end of the restricted passage ||3 of the valve body. For establishing a communication between the exterior of the valve assembly and the bore ||3 when the valve element is in its closed position, a restricted or minimum flow passage |4| is provided in the body |00. This minimum ow passage takes the place of the minimum flow passage 4| described in the first form of the invention. The remainder of the valve assembly in the form shown in Figures 6 and '7 is identical to the valve assembly shown in Figures l and 2.

The operation of this form of the invention is substantially the same as the first form. Normally, the valve element is unseated, as shown in Figure 6 and an upward flow through the ow passages |9 is permitted. Such upward ow will of course unseat the ball check valve |03 and will then enter the tubing string. When the liquid level in the well casing falls to a predetermined point. ,das is permitted to enter the minimum ow orice |4| with the result that the liquid column is aerated and its weight reJ duced, thereby permitting the valve element 20 to move to its closed position, as shown in Figure '7, When this occurs, flow through the passages I9 is shut off and well fiuids are admitted through the minimum flow orifice |4|. When the pressure above the valve element 20 is again built up, said element moves downwardly to anopen position and the cycle is repeated.

The provision of the ball check valve |03, which valve is located above the minimum flow orifice |4|, is not essential to the invention. However, when the Well is shut in at the surface, the liquid which has been accumulated in' In both forms of the invention, the intermty ting device is illustrated as connected to a suitable runningtool, whereby it may be readily run into or removed from the well by means of a flexible line. However, the invention is not to be limited to positioning the assembly by means of such a tool for obviously, the valve body I0 in the first form and |00 in the second form could be directly coupled to the well tubing string, in which case the assembly would be lowered with the tubing and would not be independently removable from the well.

The foregoing description of the invention is explanatory thereof and various changes in the size, shape and materialsl as well as in the details of the illustrated construction may be vmade, within the scope of the appended claims,

without departing from the spirit of the invention.

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

l. A flowing well control device wherein a tubing mounted in a Well casing has a uid inlet at its lower end, including in combination, a valve normally biased to open position mounted in the tubing string and responsive to the pressure differentialthereacross for controlling the flow of well fluids upwardly through the tubing, means for establishing a predetermined pressure differential across the valve to maintain the valve in its open position permitting an upward flow through the tubing string, and a fluid inlet to the tubing above the valve restricted to admit a reduced flow. of fluid from the casing into the tubing, said fluid inlet constantly admitting fluid, regardless of the position of the valve, the admitted flow acting on the valve to vary the predetermined differential to effect actuation of said valve to closed position.

2. A wel] control device for flowing wells includng, a Awell casing, a well tubing having a well fluid inlet mounted within the casing, a valve mounted in the tubing above the inlet and responsive tothe differential in pressures thereacross for controlling the flow through the tubing, resilient means urging the valve to an open position, whereby a predetermined pressure differential across the valve is required to actuate the same, and a fluid inlet to the tubing above said valve restricted to meter the flow of fluid from the casing to the tubing, said fluid inlet constantly admitting fluid to the tubing, the admittance of gaseous fiuid through the restricted fluid inlet acting to lighten the column of flowing fluid above the valve to increase the pressure differential thereacrcss and permit closing of the valve to shut off flow through the tubing.

3. A well control device for flowing wells including, a well casing, a well tubing having a wel fiuid inlet mounted within the casing, a valve mounted in the tubing above the inlet and responsive to the differential in pressures thereacross for controlling the flow through the tubing, resilient means urging the valve to an open position, whereby a predetermined pressure differential across the valve is required to actuate the same, a fluid inlet to the tubing above said valve restricted to meter the lflow of fluid from the casing to the tubing, the admittance of gaseous iluid through the restricted fluid inlet acting to lighten the column of flowing Vfluid above the valve to increase the pressure differentalthereacross and permit closing of the valve to shut oil ilow through the tubing, and separate means exposed. to the well fluids for causing the valve to reopen.

4. A well control device for flowing wells including, a well casing, a well tubing having a well fluid inlet mounted within the casing, a valve mounted in the tubing above the inlet and responsive to the differential in pressures thereacross for controlling the flow through the tubing, resilient means urging the valve to an open position, whereby a predetermined pressure differential across the valve is required to actuate lthe same, and a fluid inlet to the tubing above said valve restricted to meter the ilow of fluid from the casing to be tubing, the admittance of gaseous iluid through the restricted iluid inlet acting to lighten the column of flowing Iluid above the valve to increase the pressure diiferential thereacross and permit closing of the valve to shut off flow through the tubing, said restricted iluid inlet acting to admit liquid to the tubing above the valve after the valve has closed, wherebir a liquid column is built up to again open the valve when said column exerts a predetermined hydrostatic head on the valve.

5. A llowing well control device wherein a tubing mounted in a well casing has a fluid inlet at its lower end, including in combination, a'valve normally biased to open position mounted in the tubing string and responsive to the pressure dif- :erential thereacross for controlling the flow of well iluids upwardly through the tubing, means for establishing a predetermined pressure differential across the valve to maintain the valve in its open position permitting an upward flow through the tubing string, and constantly open means for admitting gas from the casing into the tubing above the valve to lighten the column of flowing fluid and thereby change the differential across the valve to close said valve, said gas being admitted to the tubing when the liquid level in the casing falls below a predetermined point, whereby a liquid seal is constantly maintained around the well fluid inlet to the tubing and to @dect actuation of the valve to closed position.

6. A well control device including, a well fluid conductor having a well iluid inlet for conducting well fluids from the lower end of a well bore to the surface, a valve seat within said conductor, a valve element normally biased toward open position and movable relative to said seat for controlling the flow through the conductor, said element having its upper end exposed to the pressure in the conductor above the element and its 'lower end exposed to the pressure in the conductor therebelow, whereby the element is actuated by the differential in such pressures, and a fluid inlet for constantly admitting well iluids into the conductor above the valve whereby such well fluids are added to the column above the valve to vary the dilerential across the valve and thereby effect actuation of said valve to closed position.

7. A well control device including, a well fluid conductor having a well fluid inlet at its lower end communicating with the producing formation for conducting well fluids to thel surface, a valve body mounted in the conductor and having its bore communicating with the bore of the conductor, a guide block mounted within the body and having flow passages therein for permitting an upward flow through the body, said passages setting up a predetermined pressure drop thereacross, a valve element slidable in the block with its upper end exposed to the pressure ln the conductor thereabove and its lower end eXpOsed to the pressure in the conductor below the guide block, whereby the element is actuated by the differential in such pressures, and a uid inlet to the conductor above the valve element restricted to admit well fluids to the tubing above said valve, said admitted iluid acting on the column of flowing fluid when the valve is open to effect closure thereof and acting on the valve when the same is closed to eifect opening thereof.

8. A well control device including, a well casing having its lower end communicating with the producing formation and its upper end closed, a well tubing extending through the well casing and having its lower end communicating with the casing, whereby well iluids may ilow upwardly through the tubing to the surface, a, valve seat within the tubing string, a valve element normally biased toward open position mounted within the tubing and movable relative to said seat for controlling upward flow through the tubing, said valve being responsive to the pressure differential thereacross, and a constantly open restricted uid inlet to the tubing above the valve and independent of the latter for establishing communication between the casing and tubing, said inlet functioning to admit gas from the casing into the tubing when the liquid level in the casing falls to a predetermined point, whereby the admitted gas lightens the flowing column of fluid in the tubing to vary the pressure differential across the valve element and effect closure thereof.

9. .A well control device including, a well casing having its lower end communicating with the producing formation and its upper end closed, a well tubing extending through the well casing and having a well fluid ilet communicating with the casing, whereby well fluids may flow upwardly through the tubing to the surface, a valve seat within the tubing string above the well iluid inlet, a valve element normally biased toward open position mounted within the tubing and movable relative to said Seat for controlling upward flow through the tubing, said valve being responsive to the pressure differential thereacross, means for establishing a predetermined pressure differential across the valve, whereby the valve is normally open to permit flow, and a reduced fluid inlet to the tubing above the valve and independent of the latter for establishing constant communication between the casing and tubing regardless of the position of the valve, said inlet functioning to admit gas from the casing into the tubing when the liquid level in the casing falls to a predetermined point, whereby the admitted gas lightens the flowing column of iluid in the tubing to effect closure of the valve element, the inlet also acting to admit liquid to the tubing after the valve is closed, whereby a liquid column sufllcient to effect re-opening of said valve is built up.

l0. A well control device including, a well casing having its lower end communicating with the producing formation and its upper end closed, a well tubing extending through the well casing and having a well fluid inlet communicating with the casing, whereby well fluids may flow upwardly through the tubing to the surface, a valve seat within the tubing string above the well fluid inlet, a valve element mounted within the tubing and movable relative to said seat for controlling upward flow through the tubing, said valve being responsive to the pressure differential thereacross, resilient means associated with the valve urging said valve toward its open position, and a restricted fluid inlet to the tubing above the valve for establishing constant communication between the casing and regardless of the position of the valve tubing, said inlet functioning to admit gas from the casing into the tubing when the liquid level in the casing falls to a predetermined point, whereby the admitted gas lightens the flowing column of fluid in the tubing to effect closure of the valve element against the pressure of the resilient means, the restricted fluid inlet also acting to permit equalization of pressures across the valve after the same is closed to permit the resilient means to re-open said valve.

11. A well control device including, a well casing having its lower end communicating with the producing formation and its upper end closed, a well tubingextending through the well casing and having a well fluid inlet communicating with the casing, whereby well fluids may flow upwardly through the tubing to the surface, a valve seat within the tubing string above the well fluid inlet, a valve element mounted within the tubing and movable relative to said seat for controlling upward flow through the tubing, said valve being responsive to the pressure differential thereacross, resilient means associated with the valve urging said valve toward its open position, a restricted fluid inlet to the tubing above the valve for establishing constant communication between the casing and tubing, said inlet functioning to admit gas from the casing into the tubing when the liquid level in the casing falls to a predetermined point, whereby the admitted gas lightens the flowing column of fluid in the tubing to effeet closure of the valve element against the pressure of the resilient means, the restricted fluid inlet also acting to permit equalizationl of pressures across the valve after the same is closed to permit the resilient means to re-open said valve, and means for adjusting the resilient means to control the pressure differential at which the valve operates.

12. A well device, of the character described, including a well casing, a well tubing having a well liquid inlet communicating with the casing to permit the well fluids from the casing to enter said tubing and flow upwardly therein, and a valve assembly mounted in the tubing above the inlet and having a valve element normally biased toward open position disposed in the line of flow through the tubing so as to be actuated by the differential in pressures above and below the element, said element being arranged to close upon the exertion of a predetermined pressure differential thereacross, the tubing having a restricted port above the valve element independent of the latter for establishing constant communication between the tubing and casing and for admitting gas to the tubing when the liquid level in the casing falls to a point immediately below the restricted port, admission of gas to the tubing setting up the necessary pressure differential across the valve element to effect closing of the valve and thereby prevent the liquid level in the casing falling below the well liquid inlet of the tubing to maintain a liquid seal around the liquid inlet to the tubing.

13. A well device of the character described, including a well casing, a well tubing having a liquid inletl communicating with the casing to permit the well fluids from the casing to enter said tubing and flow upwardly therein, a valve assembly mounted in the tubing above the inlet and having a valve element normally biased toward open position disposed in the line of flow through the tubing so as to be actuated by the differential in pressures above and below the element, said element being arranged to close upon the exertion of a predetermined pressure differential thereacross, the valve assembly having a restricted port above the valve element and independent of the latter for establishing constant communication between the tubing and ,casing and for admitting gas to the tubing when the liquid level in the casing falls to a predetermined point, the admission of gas to the tubing setting up the necessary pressure differential across the valve element to effect closing of the valve and thereby maintain a liquid seal around the liquid inlet to the tubing, the restricted port also functioning to admit fluid to the tubing after the valve is closed to build up a fluid column therein and thereby reduce the differential across the valve element and thereby permit re-opening thereof,

14. A well device of the character described, including a well casing, a well tubing having a liquid inlet communicating with the casing to permit the well fluids from the casing to enter said tubing and flow upwardly therein, a valve assembly mounted in the tubing above the inlet and having a valve element nor biased toward open position disposed in the line of flow through the tubing so as to be' actuated by the differential in pressures above and below the element, adjustable means associated with the valve element for permitting closure thereof at a predetermined pressure diferential thereacross, the valve assembly having a restricted port above the valve element and independent of the latter for establishing constant communication between the tubing and casing and for admitting gas to the tubing when the liquid level in the casing falls to a predetermined point, the admission of gas to the tubing setting up the necessary pressure differential across the valve element so as to effect closing of the valve and thereby maintain a liquid seal around the liquid inlet to the tubing.

15. A well device, of the character described,

' including a well casing, a Well tubing having a well liquid inlet communicating with the casing to permit the well fluids from the casing to enter said tubing and flow upwardly therein, a valve assembly mounted in the tubing above the inlet and having a valve element disposed in the line of flow through the tubing so as to be actuated by the differential in pressures above and below the element, said element being arranged to close upon the exertion of a predetermined pressure differential thereacross, the tubing having a restricted port above the valve element for estab-- lishing constant communication between the tubing and casing and for admitting gas to the tubing when the liquid level in the casing falls to a point immediately below the restricted port, the admission of gas to the tubing setting up the nef cessary pressure differential across the valve element to close the valve and thereby prevent the liquid level in the casing falling below the well liquid inlet of the tubing to maintain a liquid seal around the liquid inlet to the tubing, and check` valve means in the tubing above the restricted port for preventing a back flow of fluids downwardly through the tubing.

16. A well device, of the character described, including a well casing.' a well tubing having a well liquid inlet communicating with the casing to permit the well fluids from the casing to enter said tubing and flow upwardly therein, and a valve assembly mounted in the tubing above the inlet and having a valve element disposed in the line of ow through the tubing so as to be actuated by the differential in pressures above and below the element, said element being arranged to close upon the exertion of a predetermined vpressure differential thereacross, means attached to the valve assembly for removably locking the 'same within the tubing, the tubing having a restricte'd port above the valve element for establishing communication between the tubing and casing and for admitting gas to the tubing when the liquid level in the casing falls to a pointimmediately below the restricted port, the admission of gas to the tubing setting up the necessary pressure d iilerential across the valve element to close the valve and thereby prevent the liquid level in the casing falling below the well liquid vinlet of the tubing to maintain a liquid seal around the liquid inlet to the tubing.

17. A wel1 flowing .control device including, a iluid conductor having means for mounting it in the ow pipe of a well and provided with a fluid inlet port located intermediate its ends and constantly open, a seal above the inlet for closing of! the space between the conductor and the pipe, and a valve mounted in the conductor below the inlet port thereof and having means for holding it open during lowering of the device and during normal flow, said valve opening means having an adjustment to set said means to yield when the pressure differential across said valve is unequalized to a degree whereby the upwardly flowing well iluid will close said valve.

18. A well flowing device including, a fluid conductor, means for connecting the conductor with a well tubing and establishing flowing communication therewith, said conductor having a constantly open fluid inlet intermediate its ends, a

valve seat in the conductor below the inlet, the

conductor having a well fluid inlet below the valve seat, a valve in the conductor betweenA the valve seat and the inlet therebelow adapted to engage said seat, and means connected with the valve for controlling actuation thereof including a restraining element for maintaining said valve open during a predetermined rate of ilow of well fluid upwardly through said valve seat and a, restricted fluid passage correlated with .the valve to maintain a predetermined pressure differential across said passage, whereby the upwardly flowing iiuid seats the valve upon an increased pressure diierential.

HERBERT C. O'I'IS.

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