US2757614A

US2757614A - Free piston well pump

Info

Publication number: US2757614A
Application number: US349513A
Authority: US
Inventors: John D Spalding
Original assignee: Nat Supply Co
Current assignee: National Supply Co
Priority date: 1953-04-17
Filing date: 1953-04-17
Publication date: 1956-08-07
Anticipated expiration: 1973-08-07

Description

Aug. 7; 1956 Filed April 17, 1955 3 Sheets-Sheet 1 lwrom/a s Aug. 7, 1956 J. D. SPALDING 2,757,614

FREE PISTON WELL PUMP Filed April 17. 1953 s Sheets-Sheet s IN VEN TOR. JOA A/ 0. 5 94. D/A G United States Patent FREE PISTON WELL PUMP John Spalding, Los Angeles, Calif., assignor to The National Supply Company, Pittsburgh, Pa., a corpora tion of Pennsylvania Application April 17, 1953, Serial No. 349,513

7 Claims. (Cl. 103-522) This invention relates to free piston pumping apparatus and is particularly directed to improvements over devices of the type shown in the co-pending application of Howard C. Tait, Serial No. 289,277, filed May 22, 1952, entitled Control for Plunger Lift, now Patent No. 2,649,738.

The principal object of this invention is to provide improved Well head structure for use with the free piston pumping apparatus. A more particular object is to provrde a novel form of trigger block assembly which is removable as a unit from a side face of the bumper spring housing on the well head. Another object is to provide such an assembly having a trigger element which is contacted by the plunger and which engages an abutment stop on the trigger box to limit movement of the trigger element when the plunger is not within the bore of the bumper spring housing. Another object is to provide an improved mounting of the spear tube at the well head which functions as a mechanical opener for the valve at the lower end of the plunger. Other and related objects and advantages will appear hereinafter.

Referring to the drawings:

Figure l is a side elevation showing a well head structure embodying my invention.

Figure 2 is a sectional elevation on an enlarged scale taken substantially on the lines 2--2 as shown in Figure 1.

Figure 3 is an elevation view taken substantially on the lines 33 as shown in Figure 2.

Figure 4 is a transverse sectional view taken substantially on the lines 4-4 as shown in Figure 3.

Figure 5 is a longitudinal sectional view taken substantially on the lines 5 5 as shown in Figure 3.

Figure 6 is a side elevation partly broken away taken in the direction of the lines 6-6 as shown in Figure 3.

Figure 7 is a sectional detail similar to Figure 6 but showing the moving parts in different positions.

Figure 8 is a plan view partly broken away showing a portion of the trigger box.

Figure 9 is a schematic diagram showing a control instrument for use in connection with the free piston pumping apparatus.

In the drawings:

The well head generally designated 10 is mounted at the upper end of the well casing 11. The eduction tube 12 is connected to the well head 10. The body of the shut-off valve 13 forms a connection between the eduction tube 12 and the nipple 14. The body 15 serves as a bumper spring housing and the upper end of the body is closed by means of the assembly cap 16. The well fluid delivery conduit generally designated 17 includes the shutoif valve 18 and serves to connect the side outlet 19 of the body 15 with the main control valve generally designated 20. This control valve is mounted in the discharge pipe downstream from the shut-01f valve 18. When the valve 20 is closed the well is shut in. The valve 20 may be of the general type shown in said Tait patent and may include a power head 21 which operates an axially movable valve stem 22. When fluid pressure is supplied through piping 23, the valve stem 22 moves downward 2,757,6l4 Patented Aug. 7, 1956 to open the valve. When fluid pressure in the piping 23 is reduced a spring, not shown, raises the valve stem 22 to close the valve.

A lateral outlet 24 on the well head is connected through a shut-01f valve 25 to a supply pipe 26. Gas under pressure is injected through the pipe 26 and passes through the valve 25 and outlet 24 into the interior of the casing 11.

In the general scheme of operation the control valve 2i) remains closed while the plunger 29 is at the lower end of the eduction tube 12. During this period the well fluid enters the eduction tube above the plunger, and casing pressure builds up as the gas is injected through the pipe 26. When the pressure reaches a predetermined magnitude the valve 20 is opened. This action serves to reduce the pressure of the gas in the eduction tube above the plunger 29. The plunger is then moved upward through the eduction tube, lifted by the pressure of the gas in the casing which continues to enter the lower end of the eduction tube as the plunger rises. A load of well fluid above the plunger is carried to the surface and is discharged through the pipe 17 and the valve 20. When the plunger 29 enters the body 15 the valve 20 closes, again shutting in the well. The plunger 29 drops down through the eduction tube 12 to the lower end thereof and the cycle is repeated.

The plunger 29 is preferably of the type shown in the co-pending application of Donald G. Knox, and James W. Lawrence, Jr., Serial No. 83,850, filed March 28, 1949, entitled Plunger Lift Device, now Patent No. 2,642,002. This plunger travels freely the entire length of the eduction tube 12. The plunger includes a tubular body 30 having a plurality of shoes 31 mounted thereon which extend into sealing engagement with the interior of the eduction tube 12. A valve 32 is mounted for movement on the lower end of the tubular body 30 and moves upward to close against the seat 33 when the plunger begins its upward travel in the eduction tube 12.

When the plunger 29 reaches the well head it in its upward travel it passes through the body of the shut-off valve 13 and through the connecting nipple 14 into the bore 34 of the body 15. The upper end of the plunger strikes a bumper plate 35 which is mounted for axial movement within a counter bore 36. A coil spring 37 mounted Within this counter bore normally acts to maintain the bumper plate 35 against the shoulder 35. A stem 39 fixed to the'bumper plate 33 extends axially of the spring 37 and passes through a guide opening 49 in a stationary bushing 41. This bushing 41 is held in place by means of the cap 16. The guide provided by the bushing 41 prevents tilting of the bumper plate 35.

A spear 42 is fixed to the bumper plate 35 and extends downwardly therefrom into the bore 34. The purpose of the spear 42 is to unseat the valve 32 and thus serve as a mechanical opener for the valve which operates when the plunger 29 enters the body 15. The spear is maintained in concentric position within the bore 34 because the stem 39 and guide bore 4b prevent tilting of the bumper plate 35.

In order to effect closing of the control valve 20 when the plunger 29 enters the body 15, I provide a trigger element 43 which is fixed to a rockshaft 44 carried on the trigger block 45. When the plunger 29 enters the bore 34 it strikes the surface 46 of the trigger element 43 thereby turning the rockshaft 44. A vent valve generally designated 47 is caused to open when the rockshaft 44 turns. Opening of the vent valve 47 serves to bleed down the fluid pressure in the pipe 48. A control instrument 49 operating in the manner described below then reduces the pressure in the piping 23 thereby closing the control valve 29.

As clearly shown in Figure 4, the body 15 is provided with a flat surface at one side and a corresponding flat surface 51 is provided on the block 45. Threaded

elements

52 and 53 serve to clamp the

surfaces

50 and 51 together in metal to metal contact. A lateral opening 54 is provided in the body 15 and communicates with the central bore 34. The outer end of this opening terminates at the fiat surface 51. An annular seal ring 55 is confined in a recess in the block 45 and serves to effect a fluid tight connection between the block 45 and body 15 about the lateral opening 54. The trigger element 43 extends through the opening 54 and into the bore 34 for contact with the plunger 29. The trigger element 43 includes a hub 56 which is secured to the rockshaft by means of set screws 57. A cavity 58 is provided within the block 45 to provide clearance for the trigger element 43 and this cavity has an entrance opening at the flat face 51 which is encircled by the seal ring 55.

As best shown in Figure 5 the trigger element 43 engages an abutment stop 59 which is formed integrally as a part of the block 45. The abutment stop 59 comprises a curved central portion 60 carried on parallel upright legs 61. These legs 61 are spaced apart so that the trigger element 43 may extend between them. The legs are joined integrally with the block 45 by means of the projections 62. The

parts

60, 61, and 62 extend forwardly from the flat face 51 and project into the lateral opening 54 provided on the body 15. Since the abutment stop 59 is carried on the block 45 and since the trigger element 43 is pivotally mounted on the same block 45 the amount or extent of projection of the trigger element 43 into the bore 34 depends on the spacing of the flat surface 50 from the longitudinal axis of the body. The same block and trigger assembly can therefore be used with any one of several sizes of plungers and eduction tubes,

The rockshaft 44 is mounted to turn within aligned bores 63 and 64 provided in the block 45. A hollow plug 65 is threadedly connected to the block 45 and carries a seal ring 66 which engages the rockshaft 44. The seal ring 66 prevents escape of pressure fluid from the cavity 58 along the bore 63. A portion 67 of the rockshaft 44 extends into the space 68 and the portion 67 is provided with a fiat face 69. Set screws 70 carried by the lever 71 engage this flat face and causes the lever 71 to turn as a unit with the rockshaft 44. One end of the lever is engaged by coil spring 72 which acts resiliently to turn the rockshaft 44 in a direction to hold the trigger element 43 in engagement with abutment stop 59. The other end of the lever 71 carries an arm 73 which engages the outer end of a movable valve element 74 which forms a part of the vent valve assembly 47. This valve element 74 is mounted to move axially within a bore 75 provided on the member 76. The member 76 is threadedly connected to the block 45. A conical head 77 on the valve element 74 is engageable with a valve seat 78 formed on the member 76. When the valve head 77 is moved away from the seat 78 pressure in the line 48 is bled to atmosphere through the opening 79. When the arm 73 holds the valve head 77 in engagement with the seat 78, the fluid pressure in the line 48 is prevented from escaping through the passage 79. A ring 80 prevents over travel of the valve element 747 A removable plug 81 is provided for access to the set screws 70 which clamp the lever 71 to the extending portion 67 of the rockshaft 44. Shims 82 are provided for adjusting the position of the member 76 with respect to the block 45 and thereby adjusting the position of the valve element 74 with respect to the lever extension 73. A transparent cover plate 83 serves as a closure for the space 68 and therefore the action of the lever 71 can readily be observed during operation. The transparent cover plate 83 is held in position by means of suitable fastenings 84. It will be noted that all of the projecting parts on the block 45 extend from the fiat surface 51. Thus the spring housing 85, plug 81, member 76, the

abutment stop 59 and the trigger element 43 all extend from the flat surface 51. The trigger element 43 and abutment stop 59 project into the body opening 54 while the plug 51 and spring housing 85 project into a clearance space 86 formed on the body 15. (See Figure 4). The exposed front face 87 of the block 45 is therefore free of projections, except for the threaded

elements

52 and 53. From the above description it will be understood that the trigger element 43 is moved from the position shown in Figure 5 to the position shown in Figure 2 when the plunger 29 enters the bore 34 in the body 15. This movement of the trigger element 43 causes the arm 71 to shift from the position shown in Figure 6 to the position shown in Figure 7. This action in turn allows the valve element 74 to move to the left as viewed in Figures 6 and 7 to permit escape of fluid under pressure from the line 48 through the vent opening 79. When the plunger 29 drops back down the eduction tube 12 and leaves the bore 34 the spring 72 acting on the lever 71 returns the trigger element 43 into contact with the abutment stop 59. At the same time the extension arm 73 engages the valve element 74 to bring the valve parts 77 and 78 into sealing relationship, thereby closing the vent opening 79.

In order to carry out the cycle of operations I provide a control mechanism of the general type shown in the Tait patent, referred to above. This control mechanism causes the control valve 20 to open when the casing pressure builds up to a predetermined magnitude, and causes the valve 20 to close when the plunger 29 enters the body 15. The control instrument generally designated 49 comprises a casing having a number of parts of the control mechanism positioned therein. Among these parts are the pilot valve 88, the relay valve 8), the bellows assembly 90, the Bourdon tube 91, and the valve assembly 92. Pilot supply gas at relatively low pressure, for example, 20 p. s. i., is supplied through conduit 93 to the terminal 94 of the relay valve 89 and to the terminal 95 of the pilot valve 88. This pilot supply gas may be obtained from any convenient source, and as shown in the drawings is obtained through a pressure reducing regulator 96 connected to the gas supply pipe 26. The line 97 is connected to the supply pipe 26 at a point near the entrance to the casing 11, and hence reflects the pressure within the casing 11. This line 97 is connected to the Bourdon tube 91. The control line 23 communicates with the power head 21 of the control valve 20, and with the terminal 100 of the bellows assembly 90. The trigger line 48 connects the vent valve assembly 47 to the

terminals

101 and 104 of the relay valve 89. The terminal 102 of the pilot valve 88 connects through line 105 with the terminal 103 on the relay valve 89.

The relay valve shown diagrammatically at 89 employs a ball 111 which may engage either an upward facing seat 112 or a downward facing seat 113. When the ball 111 rests by gravity upon the seat 112 it closes off the vent port 114. A diaphragm 115 operates a plunger 116 which may engage the ball 111 and move it upward away from seat 112 and into contact with seat 113.

I"; Pressure fluid admitted through terminal 104 operates the diaphragm 115. A restriction 118 located for convenience within the relay valve 89 connects

terminals

94 and 101 and hence establishes communication between the pressure fluid supply line 93 and the trigger line 48.

The pilot valve shown diagrammatically at 88 is provided with a valve spool 119 which moves axially within a cylindrical bore 120. An annular groove 121 in the spool 119 connects the terminal 99 with either the terminal 95 or the vent port 122, depending upon the axial position of the spool 119. A compression spring 123 acts resiliently to move the spool 119 in one direction, and such movement is resisted by fluid pressure in the chamber 124 below the spool 119.

The Bourdon tube 91 has its moving end connected to the crank arm 125 of the flapper valve 126, pivotally mounted at 127. A nozzle 128 engages the under side of the flapper valve 126 to form a seal. The nozzle 128 is also movably mounted, and as shown diagrammatically in the drawings, the nozzle is carried on an arm 129 pivotally supported at 130. A link 131 is pivoted at one end to the arm 129 and at the other end to the post 132 fixed on the end wall of the bellows 90. When the pressure in the bellows chamber 133 increases, the nozzle 128 is moved toward the flapper valve 126. One or more loops 134 in the nozzle feed pipe 135 permit the nozzle 128 to move freely through its relatively short are of movement. When pressure in the Bourdon tube increases, the flapper valve 126 is swung toward the nozzle 128. The nozzle 128 and flapper valve 126 are collectively referred to as the vent valve 92.

In the position of the parts as shown in Figure 2, the plunger 29 is in the body and the vent valve 47 is open. The trigger line 48 is therefore vented to atmosphere through vent port 79. If desired, a dash-pot mechanism, not shown, can be employed to prevent too rapid closing of the vent valve 47 in the event that the plunger 29 should descend out of contact with the trigger element 43 before any considerable pressure drop occurs in pipe 48. The release in pressure below the diaphragm 115 in the relay valve 89 allows the sliding plunger 116 to drop, and the ball 111 rests on seat 112, closing off vent port 114. Pressure from the pilot supply line 93 then passes into the relay valve 89 through terminal 94, out through terminal 103, through pipe 105, and into the chamber 124 in the pilot valve 88 through terminal 1112. The spool 119 moves up against the action of the spring 123 to close off the terminal 95 and to connect the terminal 99 with the vent port 122. The control pipe 23 is thus vented to atmosphere, and the reduction in pressure within the power head 21 of the motor valve assembly 2i) permits a spring (not shown) to lift the stem 22 to close the valve.

Venting of the control pipe 23 through vent port 122 in the pilot valve 88 serves to efiect closing of the control valve 20, as set forth above, and also acts to decrease the pressure in the bellows chamber 133. This allows the arm 129 to swing about its pivot 130 and move the nozzle 128 away from the flapper valve 126. The nozzle 128 then vents the line 135 and trigger pipe 48 to atmosphere even though pressure fluid is being constantly supplied through restriction 118 from the pilot supply pipe 93. A reduction in casing pressure is occasioned by passage of gas through the control valve during its open period. This reduction in pressure is reflected by action of the Bourdon tube in lifting the flapper valve 126 away from the nozzle 128. The plunger 29 drops back through the eduction tube 12 to the lower end thereof in the well. The control valve 20 remains closed, with the well shut in.

The plunger 29 remains at the lower end of the eduction tube 12 in the well until the casing pressure builds up to a predetermined value. The increase in casing pressure is brought about either by entry of formation gas into the casing 11 at the lower end thereof or by admitting gas under pressure through pipe 26, or both. When the pressure in the casing 11 builds up to a predetermined intensity the Bourdon tube 91 lowers the flapper valve 126 into contact with the nozzle 128, to close off the nozzle 128 and substantially prevent escape of pressure fluid therefrom.

Pressure fluid supplied through restriction 118 then builds up pressure in the line 135 and trigger pipe 48. The diaphragm 115 in the relay valve 89 is raised, causing the plunger 116 to seat the ball 111 against the seat 113. This action vents line 105 through port 114 and allows the spring 123 in the pilot valve 88 to shift the spool 119 to a position to close off the vent port 122 and to connect terminal 95 with terminal 99. Pressure fluid then passes from the pilot supply line 93 into the control pipe 23, and into the bellows chamber 133.

When the pressure in the control pipe 23 builds up sufficiently it causes the power head 21 to open the control valve 20. The gas under pressure in the eduction tube 12 then passes out through the discharge pipe 17. The consequent reduction in pressure in the eduction tube 12 above the plunger 29 causes the plunger to be driven to the surface by pressure fluid from the casing 11. A slug of well fluid is lifted by the plunger 29, and this well fluid passes out through discharge pipe 17 and control valve 21) before the plunger 29 reaches the body 15. When the plunger 29 reaches the body 15 it engages the trigger element 43, opens the vent valve 4'7, and the cycle repeats. The valve 32 in the plunger 29 is opened by the spear 42 and the plunger drops back down the eduction tube 12 into the well.

Having fully described my invention, it is to be understood that I do not wish to be limited to the details herein set forth, but my invention is of the full scope of the appended claims.

I claim:

1. In a free piston well pump device, the combination of: an eduction tube extending into a well, a valved plunger adapted to travel freely under pressure within the eduction tube, well head structure connected to the upper end of the eduction tube including a body having a bore to receive the plunger, the body having a side face provided with a lateral opening communicating with said bore, a block removably secured to the side face of the body, means sealing the block with respect to said side face, a trigger element movably mounted on the block and extending through said lateral opening for contact with the plunger when the plunger extends into said bore, and means actuated by said trigger element for regulating flow of fluid from said eduction tube.

2. in a free piston well pump device, the combination of: an eduction tube extending into a well, a valved plunger adapted to travel freely under pressure within the eduction tube, well head structure connected to the upper end of the eduction tube including a body having a bore to receive the plunger, the body having a side face provided with a lateral opening communicating with said bore, a block removably secured to the side face of the body, means sealing the block with respect to said side face, a trigger element movably mounted on the block and extending through said lateral opening for contact with the plunger when the plunger extends into said here, a discharge pipe connected to said well head structure, a fluid-actuated flow-control valve in the discharge pipe, and means including a vent valve on said block whereby movement of the trigger element serves to close said flowcontrol valve.

3. In a free piston well pump device, the combination of: an eduction tube extending into a well, a valved plunger adapted to travel freely under pressure within the eduction tube, well head structure connected to the upper end of the eduction tube including a body having a bore to receive the plunger, the body having a lateral opening communicating with said bore, a block having an abutment extending into said opening, clamp means releasably securing the block to a side face of the body in sealing relationship about said opening, a trigger element movably mounted on the block and extending through said lateral opening for contact with the plunger when the plunger extends into said bore, the trigger element engaging the abutment in the absence of the plunger to limit movement of the trigger element into said bore, and means actuated by said trigger element for regulating flow of fluid from said eduction tube.

4. In a free piston well pump device, the combination of: an eduction tube extending into a well, a valved plunger adapted to travel freely under pressure within the eduction tube, well head structure connected to the upper end of the eduction tube including a body having a bore to receive the plunger, the body having a lateral opening communicating with said bore, a block having an abutment extending into said opening, clamp means releasably securing the block to a side face of the body in sealing relationship about said opening, a trigger element movably mounted on the block and extending through said lateral opening for contact with the plunger when the plunger extends into said bore, the trigger element engaging the abutment in the absence of the plunger to limit movement of the trigger element into said bore. a discharge pipe connected to said well head structure, a flow control valve in the discharge pipe, and means including a vent valve on said block whereby movement of the trigger element serves to close said flow control valve.

5. For use with a well fluid producing device having a valved plunger adapted to travel in a well pipe and enter a well head structure at the upper end of the pipe, the improvement comprising, in combination: a body forming a part of the well head structure and provided with a lateral opening communicating with an axial bore, a block having an abutment extending into said lateral opening, clamp means releasably securing the block to a side face of the body in sealing relationship about said opening, a trigger element movably mounted on the block and extending through said lateral opening for contact with the plunger when the plunger extends into said bore, the trigger element engaging the abutment in the absence of the plunger to limit movement of the trigger element into said here, and a valve on the block opened by movement of the trigger element.

6. in a free piston well pump device, the combination of: an eduction tube extending into a well, a plunger adapted to travel freely under pressure within the eduction tube, the plunger being tubular and having a valve adapted to move upwardly relative to the plunger to closed position, well head structure connected to the upper end of the eduction tube including a body having a bore to receive the plunger, a bumper plate adapted for engagement with the upper end of the plunger and mounted for axial movement within said body, a stem fixed on the plate extending upwardly therefrom, stationary guide means engaging the stem, and a spear fixed on the plate extending downward into the bore, the spear being adapted to project into the interior of the plunger for mechanically opening said valve when the plunger reaches the upper end of its travel.

7. In a free piston well pump device, the combination of: an cduction tube extending into a well, a plunger adapted to travel freely under pressure within the educ' tion tube, the plunger being tubular and having a valve adapted to move upwardly relative to the plunger to closed position, well head structure connected to the upper end of the eduction tube including a body having a bore to receive the plunger, the body also having counterbore forming an axial continuation of said bore, a bumper plate adapted for engagement with the upper end of the plunger and mounted for axial movement within said counterbore, a coil spring in the counterbore engaging the bumper plate, a stem fixed on the plate extending upwardly therefrom through the interior of the coil spring, stationary guide means engaging the stem, and a spear fixed on the plate extending downward into the bore, the spear being adapted to project into the interior of the plunger for mechanically opening said valve when the plunger reaches the upper end of its travel.

References Cited in the file of this patent UNITED STATES PATENTS 2,001,012 Burgher May 14, 1935 2,001,552 Scott May 14, 1935 2,555,112 Brown May 29, 1951