U.S. patent application number 10/047267 was filed with the patent office on 2003-07-17 for pump-off control interrupter.
Invention is credited to Stoker, Joe Kent.
Application Number | 20030133805 10/047267 |
Document ID | / |
Family ID | 21947990 |
Filed Date | 2003-07-17 |
United States Patent
Application |
20030133805 |
Kind Code |
A1 |
Stoker, Joe Kent |
July 17, 2003 |
PUMP-OFF CONTROL INTERRUPTER
Abstract
A pump-off control system for use with an electric motor driven
pump jack assembly for operation of a down hole pump in which a
circuit interrupter device is attached to the top of the polished
rod of the pump jack and upon occurrence of fluid pound, the
polished rod imparts sufficient force on the circuit interrupter
device to open the electrical contacts of the device momentarily
interrupting power to the electric motor shutting down the pump for
a period of time determined by a time delay relay that controls the
shut down time for the well.
Inventors: |
Stoker, Joe Kent;
(Breckenridge, TX) |
Correspondence
Address: |
Robert C. Peterson
Milburn & Peterson, P.C.
Suite 1100
620 N. Grant
Odessa
TX
79761
US
|
Family ID: |
21947990 |
Appl. No.: |
10/047267 |
Filed: |
January 14, 2002 |
Current U.S.
Class: |
417/12 ;
417/45 |
Current CPC
Class: |
F04B 47/02 20130101;
F04B 49/02 20130101; E21B 47/009 20200501 |
Class at
Publication: |
417/12 ;
417/45 |
International
Class: |
F04B 049/00 |
Claims
What is claimed:
1. A pump-off control system for use in conjunction with an
electric motor driven beam pumping unit including a polished rod
attached by a wire-line carrier and hangar assembly to a horse head
of the beam and to a down hole sucker rod pump comprising: (a) an
electrical power source; (b) an interlocking pair of normally open
relays wherein the first relay of said pair must be closed before
the second relay of said pair can close; (c) a first electrical
circuit connected to the power source for energizing the first
relay after a pre-determined time delay; (d) a control device
attached to the polished rod as a component of said first
electrical circuit, the control device momentarily de-energizing
the first relay upon incurring fluid pound. (e) a second electrical
circuit connected to the power source for energizing the second
relay when the first relay is energized; and (f) a motor controller
connected to the power source for starting and stopping the
electric motor, the motor controller starting the electric motor in
response to the second relay being energized and stopping the
electric motor in response to the second relay being
de-energized.
2. A pump-off control system for use in conjunction with an
electric motor driven beam pumping unit including a polished rod
attached by a wire-line carrier and hangar assembly to a horse head
of the beam and a down hole sucker rod pump comprising: (a) an
electrical power source; (b) an electrical power circuit coupling
the power source to the electric motor for supplying power to the
electric motor; and (c) an electric motor control circuit for
connecting and disconnecting the power circuit to the electric
motor including a control device secured to the polished rod
maintaining the power circuit coupled to the electric motor until
the polished rod encounters fluid pound, causing the control device
to disconnect the power source from the electric motor for a preset
time delay period.
3. The control device of claim 1 comprising: (a) an insulating
sleeve member closed at one end by a removable insulating cap; (b)
a metallic member secured in the other end of the sleeve member and
attached to the polished rod for movement with the polished rod;
(c) a metallic cylinder slideably retained within the insulating
sleeve member having a metal plug at one end, said metal plug
normally abutting said metallic member and making electrical
contact therewith interruptible upon encountering fluid pound
force; and (d) an electrical conductor connected to the metal plug
and extending through the cap.
4. The control device of claim 3 wherein the metal plug in
Babbitt.
5. The control device of claim 3 wherein the insulating sleeve
member is plastic.
6. A pump-off control system for use in conjunction with an
electric motor driven beam pumping unit including a polished rod
attached by a wire-line carrier and hangar assembly to a horse head
of the beam and to a down hole sucker rod pump comprising: (a) an
electrical power source; (b) a first electrical circuit connected
to the power source for energizing the first relay after a
predetermined time delay; (c) a control device attached to the
polished rod as a component of said first electrical circuit, the
control device momentarily de-energizing the first relay upon
incurring fluid pound. (d) a second electrical circuit connected to
the power source for energizing a second relay only while the first
relay is energized; and (e) a motor controller connected to the
power source for starting and stopping the electric motor, the
motor controller starting the electric motor in response to the
second relay being energized and stopping the electric motor in
response to the second relay being de-energized.
7. The control device of claim 6 comprising: (a) plastic sleeve;
(b) a metal plug secured in one end of plastic sleeve and the other
end secured to the polished rod; (c) a metal member slideably
retained in the plastic sleeve resting upon the metal plug; and (d)
the metal member and the metal plug forming an electrical contact
interruptible upon occurrence of fluid pound.
8. The control device of claim 7 wherein the metal plug includes
Babbitt metal.
9. The control device of claim 7 wherein the metal member includes
at least one stackable weight.
10. The control device of claim 7 wherein the plastic sleeve is
polyvinyl chloride.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field
[0002] The device for pump-off control pertains to control systems
for pumping units generally referred to as sucker rod pumps. More
particularly the pump-off control interrupter for the pump jack
that interrupts the production cycle for a predetermined time.
[0003] 2. State of the Art
[0004] In the production of oil from the sub-service reservoir,
frequently beam type pumping units are common artificial lift
devices for producing oil. These, so called, sucker rod pumps
reciprocate a down-hole pump mechanism that lifts oil on each
upward stroke of the sucker rods and on the down stroke, oil flows
into the pump and the process is repeated. Often in producing fluid
by artificial means with sucker rod pumps, the oil flowing
reservoir surrounding the well does not flow to the pump as fast as
the pump can lift the oil and when this happens, the fluid level in
the reservoir falls below the top of the pump plunger. A limited
amount of oil, if any, flows into the barrel of the pump. At this
point, the amount of oil being pumped is decreased and on the down
stroke the pump plunger impacts the fluid with a hammer type
pounding effect joining the sucker rods. Over long periods of time,
this pounding causes fatigue and failure of the sucker rod pumping
mechanism.
[0005] Various techniques have been developed to control the
operation of the sucker rod pumps to minimize the fluid pound
effect by disrupting the pumping operation for a sufficient period
of time to permit oil from the reservoir to again increase the
volume surrounding the well bore so that the plunger of the pump is
below the fluid level and permits fluid pumping again.
[0006] U.S. Pat. No. 5,823,262 issued to Dutton discusses in some
detail the problem in detecting the pump-off condition and
providing adequate means to minimize the problem. Dutton proposes a
flow meter arrangement for determining the volume of fluid being
pumped and the pumping is shut down when measurement from the flow
meter indicates a decline in pump efficiency, which indicates that
the production fluid level in the tubing has fallen below the upper
most travel of the plunger.
[0007] Another attempt to provide a pump-off control device
utilizes the measurement of the length of time required for the
pump to down stroke with a full barrel of oil and the time interval
for the down stroke with less than a full barrel of oil. By these
two measurements, pump-off is determined and the well shut down to
prevent excessive fluid pound. The pump is allowed to pump a
predetermined number of cycles and if fluid pound is reached again,
the time is reset on the new information.
[0008] Another system for pump-off control utilizes wave-form
signals proportional to the load on the motor drawing the pump to
determine the change in load waveform when the pump is at
pump-off.
SUMMARY OF THE INVENTION
[0009] The present invention provides a pump-off control system for
sucker rod or beam pumping units, in which the pump motor is
shut-off when the sucker rod unit undergoes fluid pound, which
jolts the sucker rods. This action interrupts the electrical
circuit supplying power to the pump motor. To accomplish this,
Applicant mounts the pump-off interrupter on top of the polished
rod on the balance beam pumping unit. The interrupter has a fixed
electrical contact that moves with the movement of the polished rod
and a floating electrical contact that rests on the fixed contact.
When fluid pound occurs, there is sufficient jolt to the polished
rod to cause the fixed and floating contacts of the interrupter to
part, thus interrupting an electric circuit, which holds a normally
open contact of a time delay relay closed as long as voltage is
applied across the relay. In this fashion, when the relay opens by
interruption of the electric circuit, power to the motor is
interrupted until the electrical circuit is completed through the
time delay relay. The time delay may be set to retain the well shut
in for a sufficient amount of time to permit the fluid in the well
bore of the reservoir to rise above the plunger to again
efficiently pump oil from the reservoir.
[0010] It is therefore an object of the invention to provide a
circuit interrupter attached to the polished rod, which opens a
relay when the polished rod undergoes fluid pound shutting down the
sucker rod pump.
[0011] It is another object of the invention to provide a pump-off
interrupter mounted on the polished rod, which includes an
insulated cylinder with one end attached to a metallic cylinder
filled with Babbitt metal with a metallic disc attached to the
Babbitt metal to provide one side of an electrical contact. The
metallic cylinder is secured to the polished rod. A second metallic
cylinder, with Babbitt metal to provide sufficient weight, secures
a metallic disc to form the other side of an electrical contact,
such that the contact is maintained during normal pumping operation
of the balance beam pump and upon incurring fluid pound, the two
contacts will separate from the impact shutting down the pump.
[0012] It is an additional object of the invention to provide a
pump-off control mounted on the polished rod, which includes a
plastic cylinder with one end securely attached by metallic
material to the polished rod to provide one side of an electrical
contact within the plastic cylinder. A metallic cylinder with
metallic material secured in one end to form the other side of an
electrical contact, including a series of removeable metal disc to
provide sufficient weight to maintain the contact closed during
normal operation and responding to fluid pound to break the
electrical connection.
BRIEF DESCRIPTION OF DRAWINGS
[0013] FIG. 1 is a schematic illustration of a walking beam, sucker
rod pump system.
[0014] FIG. 1a illustrates the positioning of the pump-off control
attachment to the polished rod of the pump system in FIG. 1.
[0015] FIG. 2 illustrates the pump-off control separation of the
contacts on impact.
[0016] FIG. 3 illustrates the pump-off control in the normally
closed position.
[0017] FIG. 4 is a schematic diagram of the motor control circuit
of the pump-off control.
DESCRIPTION OF THE PREFERRED EMBODIMENT(S)
[0018] Referring now to FIGS. 1 and 1a, a pump control system 10
consisting of a walking beam type pump jack 12, having a typical
walking beam 13 with a horse head 14 and the walking beam 13
mounted on an a-frame 16 at pivot 17. Counter weight crank 18,
driven through gear box 20 by electrical motor 21, is attached to
the rear of walking beam 13 by a pair of pitman arms 19. Wire-line
hangar 23 attached to horse head 14 by cable 24 is secured to
polished rod 25. Polished rod 25 is connected to sucker rods
extending from the reservoir to wellhead 28 in the production
tubing (not shown).
[0019] The pump-off control device (sometimes referred to as POC)
30 as best seen in FIGS. 2 and 3 consists of a rod box 32 threaded
onto polished rod 25 and includes a quantity of Babbitt material 33
to provide some weight to rod box 32. On top of the Babbitt
material is metallic disc 34 secured by the Babbitt material to rod
box 32. Cylindrical sleeve 35 is secured to cylindrical rod box 32.
Cylindrical sleeve 35, made of insulating material, has a plastic
cap 37. The cap is threadably secured to cylindrical sleeve 35 and
has a grommet 38 to sealably engage wire 39, which extends through
the grommet and is connected to control box 50. A second
cylindrical rod box 41 contains Babbitt material 42, which secures
bolt 43 with head 44 buried in Babbitt material 42. Bolt 43 has a
pair of nuts 45, which secure wire 39. Metallic contact or disc 47
is secured to Babbitt material 42 facing metallic disc 34. Metallic
contact or disc 47 and metallic contact or disc 34 provide smooth
contact surfaces for rod box 41 and rod box 32, respectively, to
provide good electrical contact therebetween. Rod box 41 is of a
lesser outer diameter than the inner diameter of cylindrical sleeve
35 and is free to slide up and down in cylindrical sleeve 35. For
purposes of adjusting the weight of rod box 41, metallic weights
49, may be inserted in rod box 41 surrounding bolt 43. The weight
adjustment may be readily done in the field by removing plastic cap
37, sliding rod box 41 out of the top, far enough to remove nuts 45
from bolt 43 and inserting one or more metallic weights 49 inside
rod box 41 and reassemble with nuts 45 re-attached to bolts 43
securing wire 39 to bolt 43. Likewise, if metallic weights 49
initially in rod box 41 are too heavy for operations, they may be
removed in the field in the reverse manner as if they were being
added.
[0020] Transformer T is attached to line L1 and line L2 of power
source S, providing 480 volt 3-phase power for operation of motor
21. Transformer T provides 110 volt power to control box 50.
Control box 50 houses auto switch 51, motor controller 52, dual
normally opened relay F2 and normally opened delay relay F1.
Pump-off control 30 completes the electrical circuit through
contacts 34 and 47 and wire 39 to the coil of time delay relay F1
providing power to maintain the contacts of normally open delay
relay F1 closed. Optionally, timer F4 may be provided in control
box 50 or externally to provide a read out of the cycles and/or
cumulative time pump jack 12 operated to pump oil.
[0021] Referring to FIG. 4, the operation of the pump-off control
system is best described beginning with pump jack 12 operating in
the normal manner without fluid pound occurring at this time rod
box 41 remains with metallic disc 47 firmly seated on metallic disc
34. Upon fluid pound occurring, rod box 32 transmits the impact of
fluid pound through metallic disc 34 to metallic disc 47, secured
to rod box 41, which is free to move in cylindrical sleeve 35. The
impact causes separation of metallic disc 47 from metallic disc 34,
thereby interrupting the electrical circuit supplying power to the
coil of delay relay F1, which holds the contacts of delay relay F1
closed during normal operation of pump jack 12. With this momentary
interruption, the contacts of relay F1 open. Since the contacts of
normally open relay F2 are maintained closed, as long as the
contacts of delay relay F1 are closed, upon the opening of the
contacts of delay relay F1 by the momentary separation of metallic
disc 47 and metallic disc 34, the contacts of relay F2 open and
opens the circuit from auto switch 51 to motor controller 52
interrupting the power to motor controller 52 and shuts down motor
21 and also stops timer F4. After the momentary interruption of
power to delay relay F1 caused by the separation of metallic disc
47 from metallic disc 34, normally open delay relay F1 begins
counting the delay before being energized at which time the
contacts of delay relay F1 will close restoring ground to normally
open relay F2. This time delay may be of any appropriate length
from several minutes to sixteen hours or more. Once normally open
relay F2 is grounded, it becomes energized and the contacts of
relay F2 close completing the circuit to provide power from power
source S through auto switch 51, relay F2 to motor controller 52
and at the same time provides power to timer F4, at which time
motor controller 52 starts pump motor 21, at the same time timer F4
begins to count. Pump motor 21 and consequently pump jack 12
operate until fluid pound is once again encountered, at which time
delay relay F1 opens due to loss of power, which causes normally
open relay F2 to open shutting off the power to motor controller 52
and timer F4. The operations of motor controller 52 and timer F4
recommence when the time delay of delay relay F1 expires and relay
F1 becomes energized and the contacts of delay relay F1 close
completing the electrical circuit through the coil of normally open
relay F2, which in turn is energized and closes the contacts
restoring power to motor controller 52 and timer F4.
[0022] A typical pump-off control of the invention as show in FIGS.
2 and 3 would include cylindrical sleeve 35 of polyvinyl chloride
(PVC), 8 inches long and have a 11/2 inch O.D. with cap 37 being
made of the same material. Rod box 32 would have a 15/8 inch O.D.
and would be filled to depth of 1 inch with Babbitt material and
washer 34 would have a 1{fraction (7/16)} inch O.D. Rod box 41
would have a 11/2 inch O.D. and would be 4 inches long. Rod box 41
would include a 13/4 inch depth of Babbitt fill and would secure a
21/2 inch bolt with 3/8 inch diameter extending vertically in rod
box 41. Washer 47 with a 1{fraction (7/16)} inch O.D. would be
secured to the bottom of Babbitt material 42 of rod box 41. Bolt 43
would have two nuts 45 to secure wire 39. Disc 49 would have a 11/4
inch diameter and 1/2 inch thick with a {fraction (5/16)} inch
center hole to fit over bolt 43.
[0023] Suitable relays for use as normally open delay relay F1 and
normally open relay F2 may be obtained from Dayton Electric Mfg.
Co., Niles, Ill. Motor controller may be obtained from Cutler
Hammer suppliers. The time may be obtained through regular
commercial suppliers of motors and timing devices, such as Cramer
Company, Old Saybrook, Conn.
[0024] It should be understood that various other arrangements of
the control circuit are possible with the pump-off control system
of the present invention to shut-in the well upon occurrence of
fluid pound affecting the pump-off control and interrupting the
continuity of the control circuit.
* * * * *