US2993447A - Apparatus for control of fluidoperated pumps - Google Patents

Description

July 25, 1961 D. E. MARQUIS 2,993,447

APPARATUS FOR CONTROL OF FLUID-OPERATED PUMPS Filed Nov. 17, 8

FIG. 2

INVENTOR. D.E. MARQUIS BY M FIG. 3

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POWER OIL PRODUCED O|L& EXHAUST POWER OIL A TTORNEYS United States Patent 2,993,447 APPARATUS FOR CONTROL OF FLUID- OPERATED PUMPS Duane E. Marquis, Bartlesville, 0kla., assignor to Phillips Petroleum Company, a corporation of Delaware Filed Nov. 17, 1958, Ser. No. 774,249 11 Claims. (Cl. 10346) This invention relates to apparatus for control of fluidoperated pumps. In a more particular aspect the invention relates to apparatus for automatically controlling the rate of flow of operating of power fluid for driving a fluidoperated pump unit.

The invention is especially applicable to the operation of a hydraulic subsurface pump unit in connection with the recovery of oil from oil wells. It is obvious, however, from the ensuing description that the apparatus can be employed in other services.

In pumping oil from a well it is conventional practice to employ a hydraulic or fluid-operated subsurface pump unit well below the ground level and submerged in the oil to be pumped. Such a pump has a fluid motor which is operated by power oil pumped from the surface down to the fluid motor. The oil in the well is pumped to the surface through a production tubing. Ordinarily, great depths are involved, and a number of conditions not readily detectable at the surface can afiect the operation of the pump adversely. In the past the rate of operation of the fluid motor, and therefore of the pump has been controlled at the surface merely by regulating the power oil rate at the surface. The operation of such pumps are adversely affected by conditions such as fluctuations in the pumping load which can cause the pump to race when the load lightens and to incur hydraulic shock when the load returns. For instance, there should always be a certain minimum head of fluid above the pump inlet in the well in order to provide a suflicient net positive suction head to prevent vaporization within the pump itself. Other conditions which sometimes exist to affect the pump load include the entrainment of gases with the oil into the pump suction, with subseqent discharge of gases into the production tubing, thus lessening the head of the discharge side of the pump and reducing the work required by the pump, with resultant increase in the rate at which the pump operates unless the supply of power oil is throttled. Another condition which can cause a change in the pump load is occasional pumping of slugs of water together with oil, thus also changing the pressure on the discharge side of the pump when the Water enters the production tubing.

Therefore, an object of the present invention is to provide a governor for controlling the rate of flow of power fluid to a fluidoperation pump in which the rate of operation of the pump is regulated in accordance with the load or work required by the pump. It is also an object of the invention to control the rate of operation of a fluidoperated pump in accordance with the hydraulic head of fluid to be pumped on the suction of the pump.

Other objects, as well as advantages and aspects, of the invention will become apparent from the accompanying disclosure and the description of the appended drawings.

The invention will be better understood by reference to a description of the drawings, of which FIGURE 1 is a general view of a well showing a well casing, submerged hydraulic pump, supply tubing for supplying power fluid, a governor for controlling the rate of said power fluid, and production tubing for conveying produced oil and exhaust power oil to the surface. FIGURE 2 is an elevation in detail of one embodiment of my governor, while FIGURE 3 is an elevation of another embodiment of the lower valve control mechanism of my governor shown in FIGURE 2.

Referring now to FIGURES 1 and 2, 10 is a well casing in which is disposed a tubing 11 for conducting produced fluids and exhaust power oil to the surface. Also disposed inside the casing 10 is a second tubing string 12. Within tubing 12 there is positioned a hydraulic subsurface pump unit 13 of conventional design. The pump unit of this embodiment is of the free type, that is, the pump can be pumped down the tubing to its position as illustrated, and by reversing the direction of flow of power oil, it can be pumped back to the surface. An example of such a pump unit is shown in volume 2 of the 1957 Composite Catalogue of Oil Field Equipment and Services, published by World Oil, Houston, Texas, at page 2896.

Inserted in the tubing string 12 above pump unit 13 is my governor for controlling the flow of power fluid to the pump 13, generally designated at 20 in FIGURE 1. The flow controller or governor is contained within an enlarged section 21 of the tubing string 12. This enlarged section is frequently called a receiving sub. Within the receiving sub there is located a sliding sleeve 22. This sleeve has a plurality of ports 23. These ports register with ports 24 in the receiving sub at any time the flow controller is in its operating position, that is, the position as shown. When ports 23 and 24 are in registry, there is communication between the annular space surrounding the tubing string and the interior of the tubing. O-ring seals are provided at 25 to seal between the receiving sub and the sleeve 22. These seals are disposed so as to isolate ports 24 and 23 from fluid above and below the point at which these ports enter the interior of the tubing. Receiving sub 21 is provided with a shoulder 26. This shoulder restricts the upward movement of sleeve 22 as will be hereinafter discussed. Receiving sub 21 has a second shoulder 29 that restricts downward movement of sleeve 22. Near the lower end of sleeve 22 is a recess 27 and a third shoulder 28. This recess and shoulder cooperate with dogs 32, -33 to be discussed hereafter. Receiving sub 21 must be separable in order to install sleeve 22. This is conveniently done by providing threads as at 19 for separating the two sections of sub 21 in order that sleeve 22 may be inserted.

The control valve proper is contained within housing 31. Housing 31 has attached to its lower end two sets of latches or dogs. These are shown at 32 and 33. Latches 32 and 33 are biased by coil springs 41 to urge them outwardly. When the flow controller assembly is pumped down tubing string 12, latch 32 engages recess 27 and shoulder 28, thus forcing sleeve 22 downwardly and causing ports 23 and 24 to register. Sleeve 22 striking shoulder 29 of receiving sub 21 prevents further downward movement and thereby retains ports 23 and 24 in registry.

Dogs 32 are held in a retracted position (shown by dashed lines in FIGURE 2) during running in operations by means of retaining ring '42. Retaining ring 42 is supported by a plurality of posts 43 which in turn are attached to ring or collar 44. Collar 44 serves as a mount for dogs 33. Collar 44 is attached to a smaller collar 45 by means of shear pins 46. Shear pins 46 are made of a soft steel or even of aluminum, copper, or brass so that they will shear at a predetermined stress. Pins 47 which hold dogs 33 to collar 44 are of a stronger material. Collar 45 is urged upwardly by compression spring 47 which rests on lower housing 48. Lower housing 48 is supported by center tube 51.

The flow controller assembly 20 is installed in the well tubing above the hydraulic pump 13. With the free type pump, this is done by inserting the pump at the surface and allowing it to fall by gravity to its operating position, or by pumping it into place by pumping power oil down the tubing string 12.

After the pump is inserted the flow controller 20 is inserted. The fiow controller falls by gravity or is pumped into position. The lower dogs 33 are urged outwardly by springs 41 but because of the angle at which these dogs extend, the flow controller is permitted to progress down the tubing string. After dogs 33 pass shoulder 28 of sleeve 22, the controller is then ready for placing in its operating position. This is done by reversing the flow of power oil momentarily so that oil flows down tubing 11 and up tubing 12. The flow controller will then tend to move up but dogs 33 prevent this. Additional pump pressure then causes the controller to move up slightly and this compresses spring 47 forcing collar 45, collar 44, posts 43 and retaining ring 42 downwardly with respect to dogs 32. Dogs 32 are thereby released to engage recess 27 and the upper face of shoulder 28. Flow of power oil is then returned to the normal direction and sleeve 22 is forced downwardly until shoulder 28 rests on shoulder 29 at which time ports 23 and 24 are in registry. During the time power oil is being pumped in the reverse direction, upwardly in tubing 12, the fiow controller 20 is prevented from being returned to the surface because dogs 33 engage shoulder 28 of sleeve 22 and sleeve 22 cannot rise higher than shoulder 26 of the receiving sub 21, It is important during the reverse flow of power oil that only small pressures be used since excess pressure will shear pins 46 and cause the device to pump upwardly out of the tubing.

To remove the flow controller from the wells all that is necessary is to reverse the flow of power oil so that oil is pumped down tubing 11 and back to the surface via tubing 12. This will unseat the pump 13 and cause it to rise upwardly to strike against the bottom end of the flow controller. Retrieving a bottom hole hydraulic pump in this manner is well known in the art and needs no further explanation here, except to state that power oil is not forced down into the well bore below pump 13 because standing valve 15 FIGURE 1) prevents such flow. When pump 13 strikes the lower surface of the flow controller, additional pressure is applied and dogs 33 force collar 44 down. A further increase in pressure will shear pins 46 because collar 45 cannot move down along tube 51 further than stop ring 52. When pins 46 shear, collar 44 will fall into the bottom space of lower housing 48,. and at the same time dogs 33 will be fully retracted so that they cannot prevent additional upward movement of the flow controller. Continued pumping of the power oil will then pump the flow controller and the pump 13 to the surface.

When flow controller is installed in its operative position, ports 23 and 24 are in registry. Power oil is pumped down tubing 12 through the conduits in the flow controller and down to pump 13 where the produced oil is mixed with the exhaust power oil for return to the surface via tubing 11. As oil from the producing formation enters the well bore, it rises to some point above the flow controller in annular space16. The height to which the oil rises will be dependent on the productivity of the well and on the rate at which the oil is pumped out of the well. Obviously, it is desirable to operate pump 13 at a high speed when a large amount of oil is available in space 16 and at a slower rate when only a small amount of oil is available. Valve 65, 66 of my flow controller will regulate the pumping rate in accordance with the amount of oil available for pumping. The amount of oil available for pumping is in direct proportion to its height in space 16 and, for that reason, the hydrostatic head of the column of oil is used to regulate the rate of flow of power oil and hence the speed of the hydraulic pump.

.The hydrostatic head created by the column of oil in space 16 is applied to the means for positioning valve 65, 66- via" ports- 24'- and 23. Ports 23 communicate with annular groove 53 in body 31. Annular groove 53 is confined by packing rings 53a which can be O-rings, chevron packing or any other suitable material. Groove 53 communicates with passageway 55 which terminates in cylinder 56. In the embodiment shown in FIGURE 2, there is disposed within cylinder 56 a piston 57 which is mounted on valve stem 61. A spring 62 urges piston 57 downwardly. Suitable packing is provided at 63 and 64 to make a seal between the valve stem 61 and the upper and lower portions of cylinder 56. It is desirable, although not absolutely necessary, that the space inside cylinder 56 above piston 57 be charged with a gas under pressure. Any suitable dry gas can be employed but nitrogen is readily available and is especially suitable. If a gas charge is employed, suitable connections for introducing the gas (not shown) are provided.

From the preceding, it will be seen that piston 57 will move upwardly in cylinder 56 in proportion to the hydrostatic pressure exerted on the underside of the piston by the column of fluid in annular space 16. As piston 57 moves, valve stem 61 will move and, thus, the opening between Valve head 65 and seat 66 will be a function of the same hydrostatic pressure. As shown in FIGURE 2, it will be noted that all pressure forces on valve stem 61 are balanced except the differential created by the hydrostatic head of oil and the bias created by the gas charge and the spring 62.

Below valve seat 66 in housing 31, there is a passage 67 within tube 51. Communicating with passage 67 is a passage 71. Passage 71 connects with conduit 71a, which in turn communicates with passage 71b communicating with a cylinder 90. Disposed in cylinder is compression spring 91 and piston 92. Piston 92 is connected to another piston 93 by valve stem 94. Piston 93 is also a valve member because it has a conical lower surface 95. This conical'surface mates with valve seat 96 in partition 101. Surrounding piston 93 is cylinder 97. There is also a passageway 98 through valve stem 94 that extends to the top of piston 93. Thus, piston 93 acts as a dash pot to regulate rate of movement of the valve.

The elements just described, cylinders 90 and 97, pistons 92 and 93, valve surface 95, valve seat 96 and valve stem 94 comprise a load responsive regulating valve. By load responsive is meant the condition whereby the bottom hold hydraulic pump engineis required to perform greater or lesser amounts of work depending upon operating conditions in the well bore that are independent of the liquid level in annular space 16. For example, if a considerable amount of gas is produced With the oil, some of this gas will be entrained in the produced oil being pumped to the surface through tubing 11. As the oil and gas approach the surface, the gas expands and frequently this expansion literally blows large volumes of oil from the tubing. When this occurs, the fluid level in tubing 11 may be, for a short time, many hundreds of feet down from the surface. The result of this is that there is a reduced back pressure on the subsurface hydraulic pump and less work required by the pump engine. In a similar manner, if the well produces varying amounts of water, it is possible under some circumstances that the column of fluid in tubing 11 will be principally water and the hydraulic gradient will be much greater than if oil only i being pumped. Under this circumstance, the pump engine is required to perform more work. This change in the Work load' on the pump engine is reflected in a change in the pressure of the hydraulic'oil power supply in passage 67. Since passage 67 is in direct communication with the underside of piston 92, this pressure is utilized to regulate the opening between valve surface and valve seat 96. Thus, the valve is responsive to pump loads,

Power oil from a surface pump unit is pumped down tubing 12 by a surface pump (not'shown) through ports 102 in housing 31 and ports 102a in cylinder 97 through the load responsive valve 95, 96, space 103, liquid level responsive valve 65,66 and thence down passage 67 to the ydraulic subsurface pump 13. Exhaust power oil and produced oil are forced up tubing 11 to the surface. My flow controller regulates the flow of power oil in accordance with the hydraulic head of oil available in space 16 as well as in accordance to the load on the pump as affected by variations in the back pressure exerted through tubing string '11.

In FIGURE 3 is shown another embodiment of the control means for the liquid level flow control valve 65, 66. As shown here, the biasing spring 62 and piston 57 have been replaced by a gas charged bellows 83. Nitro gen gas under pressure is a convenient and readily available gas. Provision for charging the bellows is made by filling connector 81, 82 with integral ball check valve. Alternately, the bellows can contain a spring biasing the valve closed.

While the flow control valve assembly 29 can be retrieved by pumping it back to the surface as has been previously described, it can also be installed or removed by wire line techniques. These techniques are well known in the industry and it is believed that no detailed explanation is required here. A fishing neck 111 is provided at the top of body 31. A suitable installation and/or removal tool can be attached to the fishing neck of the flow control valve. To install the valve, the assembly 'will be lowered by wire line to the receiving sub 21 and raised slightly to release dogs 32, thus locking the valve in position. After this, the setting tool is released and removed. To remove the valve, a removal tool is lowered through tubing 11 to engage the fishing neck 111. Pulling upward with su ficient force will shear pins 47 allowing collar 44 to fall downward thus retracting dogs 33. With dogs 33 retracted, the valve can then be withdrawn.

As will be evident to those skilled in the art, various modifications of this invention can be made or followed in the light of the foregoing disclosure and discussion without departing from the spirit and scope of the disclosure or from the scope of the claims.

I claim:

1. A governor for controlling the flow of power fluid for operation of a fluid-operated unit which is adapted to be submerged in a body of liquid comprising, in combination; a housing defining a passage for supplying said power fluid to said unit; a first valve in said passage through which all power fluid must pass in traversing said passage; a second valve in said passage through which all power fluid must also pass in traversing said passage, downstream from said first valve and arranged in series therewith; pressure actuable means responsive to a pressure differential across said second valve for operating said first valve; and pressure responsive means exposed to the fluid pressure exerted upon the exterior of said housing for operating said second valve.

2. A governor of claim 1 wherein said first valve has a dashpot operatively associated therewith.

3. A governor of claim 1 where said second valve includes a valve seat and a moveable valve member adapted to engage said valve seat to close said passage, and wherein said pressure responsive means comprises a cylinder closed at both ends, a valve stem slideably extending through said cylinder and through both ends thereof in a fluid-sealed relationship and connected at one end with said moveable valve member, a piston in said cylinder, said valve stem being rigidly aflixed to said piston at an intermediate point in said cylinder, a compression spring in said cylinder on one side of said piston urging said valve to a closed position, and a passageway communicating with said cylinder on the other side of said piston, said passageway communicating at its other end with said body of liquid to be pumped.

4. A governor of claim 3 wherein said cylinder contains a gas under pressure on the same side of the piston containing the compression spring.

5. A governor of claim 1 wherein said first valve includes a valve seat and a moveable valve element adapted to engage said first valve seat to close said first valve and wherein said pressure responsive means for operating said second valve comprises a closed vessel, a valve stem extending through one wall of said vessel in a slideable, fluid-sealed manner and connected at one end with said moveable valve element and connected at the other end with a compressible diaphragm contained within said closed vessel, said closed vessel being in fluid communication with said body of liquid to be pumped.

6. In a fluid-operated pumping apparatus for use in wells, the combination of: a fluid-operated pump submerged in well fluid in a well; a first conduit for conveying power fluid for operating said pump downwardly through the well to said pump; a second conduit connected with the outlet of said pump for conveying pumped liquid upwardly through said well; governor means in said first conduit adapted to control the rate of flow of power fluid therethrough, said governor means including a first valve in said first conduit through which all power fluid must pass in traversing said first conduit, a second valve in said first conduit through which all power fluid must also pass in traversing said first conduit fluid, said second valve being downstream from said first valve and arranged in series therewith, pressure actuable means responsive to a pressure differential across said second valve for operating said first valve, and pressure responsive means exposed to the fluid pressure of said well fluid in said well for operating said second valve.

7. A governor for controlling the flow of power fluid for operation of a fluid-operated unit which is adapted to be submerged in a body of liquid comprising, in combination; a housing defining a passage for supplying said power fluid to said unit; a first valve in said passage through which all power fluid must pass in traversing said passage; a second valve in said passage through which all power fluid must also pass in traversing said passage, down stream from said first valve and arranged in series therewith; pressure actuable means responsive to a pressure differential across said second valve for operating said first valve.

8. A governor of claim 7 wherein said first valve has a dash pot operatively associated therewith.

9. A governor of claim 7 wherein said first valve includes a valve seat and a moveable valve element adapted to engage said first valve seat to close said first valve, and wherein said pressure actuable means comprises a valve stem connected to said moveable valve element, a cylinder, a piston in said cylinder, said piston being connected to said valve stem, and said piston being exposed on one side to fluid pressure existing upstream of said first valve and on the other side to fluid pressure existing downstream from said second valve.

10. A governor of claim 9 wherein said cylinder contains a compression spring on said other side of said valve tending to urge said first valve toward an open position.

11. A governor of claim 10 wherein said moveable valve element is associated operatively with a dashpot for damping the action of said moveable valve element, said dashpot being in fluid communication, through an opening in said valve element and said valve stem, with the fluid downstream from said first valve.

References Cited in the file of this patent UNITED STATES PATENTS 2,266,356 Coberly Dec. 16, 1941 2,589,668 Coberly Mar. 18, 1952 2,637,276 Coberly May 5, 1953 2,703,585 Coberly Mar. 8, 1955

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