US2601654A - Automatic choke control - Google Patents

Description

' June 24, 1952 c. B. WRIGHT AUTOMATIC CHOKE CONTROL Filed April 1, 1949 Patented June 24, 1952 UNITED STATES PATENT OFFICE 2,601,654 AUTOMATIC CHOKE CONTROL Charles B. Wright, McFaddin, Tex.

Application April 1, 1949, Serial No. 84,872

4 Claims.

This invention relates to an automatic choke control or blowout preventer for oil and gas wells and which constitutes an improvement on my prior U. S. Patent No. 2,138,719, issued November 29, 1933, entitled Blow-Out Preventer.

More particularly, it is an object of the present invention to provide a novel automatic choke control for use in flow lines of high pressure wells producing gas or oil for automatically controlling the rate of flow from the well for regulating the pressure therein to eliminate the possibility of an increase in flow from the well beyond its capacity and which would lower the pressure in the well to permit sand and water to enter and which in passing out at the point where the pressure is greatly reduced will result in friction and in the cutting out of the tubing and regulating valve with resulting loss of the well and possible injury to workmen in attempting to close the well.

Another object of the invention is to provide an automatic choke for controlling the flow from a well and which may be adjusted to regulate it for operation under any desired rate of flow.

Still a further object of the invention is to provide an automatic choke control having means for efiectively excluding sand from parts of the choke control which would be injured thereby.

Still a further object of the invention is to provide a choke control of extremely simple construction composed of few parts and capable of being readily assembled and disassembled for the replacement or repair thereof or for applying chokes of different sizes and which may be quickly and easily interposed in the flow line of a well.

Other objects and advantages of the invention, in addition to those set forth in my prior patent, previously referred to, will hereinafter become more fully apparent from the following description of the drawing, illustrating a presently preferred embodiment of the invention, and wherein:

Figure 1 is a side elevational view, partly in section showing the choke control unit;

Figure 2 is a longitudinal substantially central sectional view, partly in side elevation, thereof, and

Figure 3 is a cross sectional view of the choke control taken substantially along a plane as indicated by the line 33 of Figure 2.

Referring more specifically to the drawing, the automatic choke control in its entirety is designated generally 5 and includes a pipe 6 constituting the cylinder or casing of the choke control and having externally threaded ends I one of which is engaged by an upper collar or threaded coupling 8 and the other of which is engaged by a corresponding lower collar or coupling 9, which collars are provided with inwardly opening annular shoulders I0 against which the ends of the tube 6 abut when the collars 8 and 9 are in fully applied positions. Said tube ends are provided with outwardly opening annular grooves H for receiving resilient packing rings I2 which abut against the shoulders I0 and are compressed in said grooves by engagement therewith for sealing the joints between the tube 6 and collars 8 and 9.

Said collars 8 and 9 are provided with restricted internally threaded openings I3 at their opposite, outer ends and said opening I 3 of the upper collar 8 detachably engages an intermediate externally threaded portion M of a nipple or pipe I5, one end of which projects upwardly from the collar 8 and isexternally threaded as seen at I6 at its outer end for engagement with a portion of a flow line of an oil or gas well, in the same manner as the nipple 26 of my prior Patent 2,138,719, as illustrated in Figure 1 thereof, so that the nipple or pipe I 5 constitutes the inlet end of the choke control 5. The nipple or pipe I5, between the collar 8 and its end I 6, is provided with a radially threaded opening I? communicating with the bore thereof to receive a pressure release valve, not shown, such as the valve 21 of my aforementioned patent and by means of which the pressure in the pipe I5 may be released, for a purpose which will hereinafter become apparent. The opposite end It of the pipe or nipple I5 is externally restricted in diameter from the threaded portion M to the end thereof and said restricted portion l 8 extends through the collar 8 and into the tube or casing 6 and is provided at its inner, lower end with an internally enlarged portion I 9.

A choke holder or piston 20 is reciprocally mounted in the tube or cylinder E5 and is provided with a restricted externally threaded upper end ill for receiving and threadedly engaging the internally threaded lower end of a sleeve 22 which extends upwardly therefrom within the cylinder or tube 6 and which is disposed loosely around the pipe portion I 8. Said restricted upper end 2| of the piston or choke holder 20 is provided with a centrally disposed upwardly opening internally threaded recess 23 for receiving a choke, designated generally 24 which is externally threaded for engaging the thread of the recess 23 and which is of annular construction to define a choke bore 25 therein which may vary in size depending upon the capacity of the well with which the choke control 5 is to be used and the normal desired flow therefrom which will be permitted by the choke control. The choke 24 is provided with turning tool receiving notches 26 in its upper end for receiving a tool, not shown, for applying the choke to or removing it from the threaded recess 23. The holder or piston 20 is provided with a longitudinally extending bore 21 the upper end of which opens into the recess 23 and which communicates with the choke bore 25 and is normally of a greater diameter than said choke bore.

The piston or holder 20 is provided with an elongated lower portion 28 of a restricted external diameter, the upper portion 29 of which is of a slightly enlarged diameter to define a support for the upper convolution of an expansion coil spring 30 which seats against the annular downwardly facing shoulder 3| of the piston or holder portion which is disposed directly above said restricted portion 29. The lower end of the spring 36 seats against a sealing ring 32 of L shaped cross section which is disposed in the lower collar 9 and which seats against the end of a restricted externally threaded end 33 of a coupling or nipple 34, which end 33 is attached to the lower collar 9 by engagement with its outer, internally threaded end [3. Said nipple or coupling 34 is provided with an opposite, lower externally threaded and restricted end 35 which is adapted to threadedly engage another adjacent end of the pipe line in which the choke control 5 is interposed, corresponding to the end 31 of the nipple 36 which is threaded connected to the pipe line portion 24 of my prior patent, aforementioned.

The piston or holder 20 includes a frustoconical portion 36 which forms a continuation of the lower end'of the restricted portion 28 and which has a restricted extension 31 which projects from the lower end thereof and which is received in a recess or socket 38 which opens outwardly of the upper end of a needle valve 39 which extends downwardly therefrom through the lower end portion of the cylinder 6, through the collar 9 and into the upper end of the nipple 34. A pin 40 engages aligned openings AI and 42 in the extension 37 and needle valve 39, as seen in Figures 2 and 3, for detachably connecting the needle valve to the choke holder or piston 25.

The nipple 34 has a bore 43 extending longitudinally therethrough and including a downwardly or inwardly tapered frusto-conical portion 45 formed in the upper end 33 thereof and into which the lower, free end of the needle valve 55; extends. The lower end of the needle valve 39 terminates in a downwardly tapered conical portion 45 which is substantially smaller than the frusto-conical passage 44 but the enlarged end of which is larger than the restricted end of the passage 26 and which valve portion 45 is normally disposed in the passage 54 but out of contact therewith, as illustrated in Figure 2 so that gas or fluid may pass readily and freely through the nipple or coupling 34 in a downward direction, as seen in Figure 2.

The restricted piston portion 28 is provided with a plurality of upwardly converging passages 45 the upper ends of which open into the lower end of the piston bore 21 and the lower ends of which open outwardly of the frustoconical piston portion 36 so that the bore 25 of the choke, the piston bore 21 and said passages 46 combine to form a passage through the piston '4 2|] from the pipe I5 to the lower end of the tube or cylinder 6.

The externally enlarged portion 41 of the piston 20 is slightly spaced from the internal annular wall of the cylinder or tube 6 to provide a slight clearance therebetween and the sleeve 22 has substantially the same clearance with respect to the cylinder bore. The spring 30 normally urges the piston 25 upwardly relatively to the cylinder or tube 6 so that its upper end seats against the lower end of the pipe portion l8 which forms a stop for limiting the upward movement of the piston 20 under the biasing action of the spring 30. With the parts thus disposed in their normal positions, as illustrated in Figure 2, the conical valve end 45 is out of contact with the frusto-conical passage 44 which forms a seat for said valve 45, so that the valve is in an open position to permit gas or fluid from a well to pass through a flow line in which the choke 5 is interposed, entering said choke through the pipe l5 and passing through the choke bore 25, through the piston bore 21 and passages 46 into the lower portion of the cylinder 6 and thence through the nipple 34 back into the flow line. The rate of flow is limited by the size of the choke passage 25 and it will be readily apparent that by providing chokes 24 having passages 25 of different diameters, the rate of flow of the choke control 5 may be readily varied as required depending upon the capacity and pressure of a particular well. Should an excess pressure occur in the well creating an excess flow through the pipe line or flow line, a pressure will be built up in the pipe is due to the restricted passage afforded by the choke passage 25 which will force the piston or choke holder 20 downwardly against the action of the spring 39 until the valve 45 seats in the valve seat or passage 44 to thereby close the automatic choke 5. Due to the differences in diameter of the portions 44 and 45, said valve 45 will only contact the seat 44 adjacent its restricted inner or lower end. The spring 30 by normally holding the upper restricted end 2| of the piston 26 in seating engagement with the lower end of the pipe 15 causes the gas or fluid to be directed into the choke passage 25 and effectively prevents the gas or fluid from passing through the cylinder 6 around the piston 20. The pipe portion I 8 also functions with the upwardly extending sleeve 22 which is disposed therearound to effectively seal out sand and other foreign matter which might otherwise pass upwardly through the cylinder 6 around the piston 253 and prevent the upper end of the piston from properly seating on the end of the pipe portion [3, since the sleeve 22 extends to normally above the upper end of the cylinder 6 and may even seat against the annular shoulder 41, formed by the restricted end I8 of the pipe I5. In the event that the choke control 5 is closed by the valve 45 seating in the valve seat 44, pressure in the pipe [5 above the choke 24 must be released through the valve connected to the tapped opening 11, before the spring 30 can return the valve 45 to its open position of Figure 2.

It will thus be readily apparent that the automatic choke control 5 will effectively function to prevent an excess flow from a pipe line, not shown, in which said choke control is interposed to prevent damage to manually controlled, regulating valves of said pipe line, not shown, such as are disclosed in my prior patent, and which would otherwise permit an excess flow from the well with resulting lowering of the pressure in the well and damage thereto and to the well tubing. It will also be apparent, and as previously described, that chokes 24 having ports or passages 25 of different sizes may be readily applied to the piston 20 for varying the capacity of the choke control 5 to accommodate it to wells of different capacities and pressures.

Various modifications and changes are con templated and may obviously be resorted to. without departing from the spirit or scope of the invention as hereinafter defined by the appended claims.

I claim as my invention:

1. An automatic choke control for flow lines of gas or oil wells comprising a cylinder, coupling means detachably connected to the ends of said cylinder for interposing the choke control in a flow line including a nipple positioned at the outlet end of the cylinder, said nipple having a passage extending therethrough including a valve seat, a piston reciprocally disposed in said cylinder having a passage extending longitudinally therethrough and including an enlarged end located adjacent the inlet end of said cylinder, a choke member removably mounted in said enlarged end of the passage and having a restricted choke bore communicating with the piston passage and inlet end of the choke control, an inlet pipe connected to and forming a part of the coupling means at the inlet end of the cylinder having an externally restricted end extending into the cylinder and normally engaging an end portion of the piston which is disposed around the choke, a valve connected to and projecting from the opposite end of said piston and supported thereby for movement therewith longitudinally of the cylinder and having a free end extending into the nipple passage for engagement with the valve seat thereof, in one position of the piston, for closing the choke control,

expansion spring means biasing the piston into engagement against the restricted end of the inlet pipe and urging the valve toward an open position, and a sleeve carried by the piston and projecting from the first mentioned end thereof toward the inlet end of the choke control, said sleeve being loosely disposed around said externally restricted end of the inlet pipe and combining therewith to form a shield for preventing sand and other foreign matter from escaping through the cylinder around the piston and toward the inlet end of the choke control.

2. A choke control as in claim 1, the inlet end of said choke member extending into said restricted pipe portion when the piston is held in engagement therewith by said spring means.

3. A choke control as in claim 1, said valve seat comprising a frusto-conical passage portion having it enlarged end opening toward the out-- let end of the cylinder. and said valve having a conical shaped end disposed remote to the piston and extending into said frusto-conical valve seat of a size for seating engagement with the valve seat adjacent its restricted end.

4. A choke control as in claim 1, said sleeve being detachably connected to the piston by threaded engagement with the first mentioned end thereof, around and outwardly of said choke member.

CHARLES B. WRIGHT.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 911,005 Garman Jan. 26, 1909 2,138,719 Wright Nov. 29, 1938 2,179,144 Buttner Nov. 7, 1939 2,411,392 Saville Nov. 9, 1946

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