U.S. patent application number 11/824057 was filed with the patent office on 2009-01-01 for short stroke piston pump.
This patent application is currently assigned to BLACKHAWK ENVIRONMENTAL CO.. Invention is credited to Mark Bertane.
Application Number | 20090000790 11/824057 |
Document ID | / |
Family ID | 40159003 |
Filed Date | 2009-01-01 |
United States Patent
Application |
20090000790 |
Kind Code |
A1 |
Bertane; Mark |
January 1, 2009 |
Short stroke piston pump
Abstract
A short stroke piston pump for recovering oil and/or water from
marginal stripper wells, tar sands and coal beds includes a motor
connected to one end of a drive rod, the motor capable of moving
the drive rod in a generally up and down direction. A piston is
connected to another end of the drive rod, the piston and drive rod
are disposed in a riser pipe, the piston is adapted to transport
fluid up the riser pipe as the piston moves up and down in the
riser pipe. Additionally, a controller is communicatively connected
to the motor, the controller changing speed and direction of the
motor in response to a location or status of the drive rod within
the riser pipe
Inventors: |
Bertane; Mark; (Glen Ellyn,
IL) |
Correspondence
Address: |
MARSHALL, GERSTEIN & BORUN LLP
233 S. WACKER DRIVE, SUITE 6300, SEARS TOWER
CHICAGO
IL
60606
US
|
Assignee: |
BLACKHAWK ENVIRONMENTAL CO.
Glen Ellyn
IL
|
Family ID: |
40159003 |
Appl. No.: |
11/824057 |
Filed: |
June 29, 2007 |
Current U.S.
Class: |
166/370 ;
417/415 |
Current CPC
Class: |
E21B 43/126
20130101 |
Class at
Publication: |
166/370 ;
417/415 |
International
Class: |
E21B 43/12 20060101
E21B043/12 |
Claims
1. A method of extracting oil from marginal stripper wells
comprising: providing a short stroke piston pump comprising: a
motor connected to one end of a flexible drive rod, the motor
capable of moving the flexible drive rod in a generally up and down
direction; a piston connected to another end of the flexible drive
rod, the piston and the flexible drive rod being disposed in a
riser pipe, the piston adapted to transport fluid up the riser pipe
as the piston moves up and down in the riser pipe; a controller
communicatively connected to the motor, the controller changing
speed and direction of the motor in response to a location or
status of the flexible drive rod within the riser pipe; installing
the short stroke piston pump in a marginal stripper well; adjusting
the controller to set a speed of the motor based on an oil yield of
the marginal stripper well.
2. The method of claim 1 further comprising adjusting the
controller to pause the motor at a bottom of a downstroke of the
flexible drive rod to compensate for drive rod float or
stretch.
3. The method of claim 1 further comprising adjusting the
controller to pause the motor at a top of an upstroke of the
flexible drive rod to compensate for drive rod float or
stretch.
4. The method of claim 1, wherein the flexible drive rod is made of
a fiberglass material.
5. The method of claim 1, wherein the flexible drive rod is greater
than approximately 1000 ft in length.
6. The method of claim 1, further comprising adjusting the motor to
produce an upstroke speed that is different from a downstroke
speed.
7. The method of claim 1, further comprising adjusting the motor
speed between approximately 50 Hz and about approximately 10
Hz.
8. The method of claim 7, wherein the motor speed is approximately
30 Hz.
9. The method of claim 1, wherein the motor moves the drive rod
between about 27 strokes per minute and about 5 strokes per
minute.
10. The method of claim 1 further comprising determining the oil
yield of the marginal stripper well.
11. A short stroke piston pump comprising: a motor connected to one
end of a flexible drive rod, the motor capable of moving the
flexible drive rod in a generally up and down direction; a piston
connected to another end of the flexible drive rod, the piston and
the flexible drive rod being disposed in a riser pipe, the piston
adapted to transport fluid up the riser pipe as the piston moves up
and down in the riser pipe; a controller communicatively connected
to the motor, the controller changing speed and direction of the
motor in response to a location of the drive rod within the riser
pipe.
12. The short stroke piston pump of claim 11, wherein the
controller pauses the motor at a bottom of a downstroke of the
flexible drive rod to allow energy stored in the flexible drive rod
to push the piston into a fluid in a well.
13. The short stroke piston pump of claim 11, wherein the
controller pauses the motor at a top of an upstroke of the flexible
drive rod to allow energy stored in the flexible drive rod to
release.
14. The short stroke piston pump of claim 11, wherein the flexible
drive rod is made of a fiberglass material.
15. The short stroke piston pump of claim 11, wherein the flexible
drive rod is greater than about 1000 feet in length.
16. The short stroke piston pump of claim 11, wherein a flexible
drive rod stroke length is between approximately 10 inches and
approximately 30 inches.
17. The short stroke piston pump of claim 11, wherein less than 10
barrels per week of oil are removed from a well.
18. The short stroke piston pump of claim 11, wherein the
controller adjusts the speed of the motor between approximately 50
Hz and approximately 10 Hz.
19. The short stroke piston pump of claim 18, wherein the
controller adjusts the speed of the motor to approximately 30
Hz.
20. The short stroke piston pump of claim 11, wherein the
controller adjusts the motor to produce a flexible drive rod stroke
frequency in the range of about 27 strokes per minute to about 5
strokes per minute.
21. The short stroke piston pump of claim 11, wherein the
controller adjusts a speed at which the flexible drive rod is
actuated.
22. The short stroke piston pump of claim 21, wherein the
controller sets an upstroke speed of the flexible drive rod
different from a downstroke speed of the flexible drive rod.
23. The short stroke piston pump of claim 11, wherein the
controller adjusts motor speed based on a liquid yield of a
well.
24. The short stroke piston pump of claim 11, wherein the motor is
electric.
25. The short stroke piston pump of claim 11, wherein the motor is
pneumatic.
26. The short stroke piston pump of claim 11, wherein the
controller can be remotely adjusted.
27. The short stroke piston pump of claim 11, wherein the short
stroke piston pump pumps oil from a marginal stripper well.
28. The short stroke piston pump of claim 11, wherein the short
stroke piston pump pumps heated bitumen from a tar sands well.
29. The short stroke piston pump of claim 11, further including a
ball screw connected to the motor and the flexible riser pipe,
wherein one revolution of the ball screw raises the piston one
inch.
30. The short stroke piston pump of claim 11, further including a
ball screw connected to the motor and the flexible riser pipe,
wherein two revolutions of the ball screw raises the piston one
inch.
31. The short stroke piston pump of claim 11, wherein the short
stroke piston pump pumps water from coal beds during methane
dewatering operations.
Description
BACKGROUND
[0001] 1. Field of the Disclosure
[0002] The disclosure generally relates to short stroke piston
pumps and more specifically to short stroke piston pumps used in
marginal stripper wells, tar sands, and/or methane dewatering of
coal beds.
[0003] 2. Related Technology
[0004] A typical oil well is drilled into the earth and oil is
pumped out with heavy duty oil pump jacks. Eventually, the oil in
the well is depleted to a point where it is no longer economical to
use the high capacity heavy oil pump jack because these heavy oil
pumps pump oil out of the well faster than the oil yield. When this
happens, the heavy oil pump jack is shut off, or in some cases, it
is removed and taken to a new well where it will be more
productive, and the first well is idled and eventually capped.
These abandoned idled wells are unused "stripper wells." Sometimes
theses stripper wells still have enough yield to be productive with
other conventional well pumps. More often, the yield of the
stripper wells is too low to make oil production economically
feasible with conventional oil well pumps. Generally, the yield in
such wells may be less than five barrels per week. These stripper
wells are called "marginal" stripper wells in the industry because
although they still produce oil, the yield is too low to make oil
production in these marginal stripper wells profitable with
conventional heavy duty oil pumps.
[0005] Typically, oil and gas fields that have stopped flowing use
an artificial means of producing the oil. The oil is extracted from
these stripper wells typically using four different types of pumps,
each being driven by electric power. However, these four types of
conventional pumps are not well suited for pumping oil from
marginal stripper wells because of each of the four conventional
pumps is designed to pump at too high a flow rate for marginal
stripper wells.
[0006] First, an electrically driven jack pump may be used. The
jack pump is constructed of heavy iron and is powered by a direct
drive totally enclosed and fan cooled electric motor. The pump jack
actuates a sucker rod which, in turn, drives a piston near the
bottom of the well in an up and down reciprocating motion. The
piston is connected to a large drive motor via a sectioned steel
drive rod. A counter weight at the opposite end of the drive rod is
used to reduce the power consumption of the jack pump and to help
pull the piston up on the return stroke. Because the pump jack is
made of heavy iron and set up in a fulcrum configuration with a
counter weight to assist the motor in pulling the piston up on the
return stroke, typical pump jacks are very heavy and expensive to
install.
[0007] Second, an electrical submersible pump may be used. The
submersible pump is similar to water well submersible pumps and
includes a submersible motor that drives a wet impeller end. This
electric submersible pump is inserted into the well and connected
to the surface by an educator pipe and a power cord. Submersible
pumps are used on high yield, high flow wells. Submersible pumps
are good for pumping both oil and high water content wells;
however, they are not good for shallow low flow wells. Because the
impeller of a submersible pump runs at a high RPM, the impeller is
susceptible to wear due to the grit and suspended particles in the
oil found in stripper wells. Furthermore, submersible pumps can be
prone to explosion because the electrical motor wire goes down to
the bottom of the well to the electric submersible drive motor.
This electric motor wire can fray and, being in proximity to
volatile gas in the oil well, can cause an explosion. A short
circuit in the motor or the power cord could trigger such an
explosion. Moreover, some electric submersible pump motor cannot
run in a dry condition. Some electric motors use pumped fluid to
cool the electric motor and if fluid is not present the motor can
over heat and destroy itself. Electric submersible pumps need to
pump at a high rate of speed to keep the electric motor cool and
many mature oil fields cannot sustain a high enough pumping rate.
Additionally, when pumping at too high a rate, the electric
submersible pumps may pump water with the oil. The oil and water
are emulsified when pumped and must be separated at the surface;
the water is pumped back into deep well injection wells, thereby
adding expense to the pumping operation.
[0008] Third, a progressive cavity pump may be used. The
progressive cavity pump may include a single external helical
section and a stator with an internal shape of a two start helix.
The stator is an elastomer bonded inside an alloy steel tube. When
a steel rotor is placed inside the stator a series of sealed
cavities are formed. As the rotor turns, these cavities progress
from the suction end of the pump to the discharge end, thereby
transporting fluid through the pump. The fluid flow rate for
progressive cavity pumps is directly proportional to the speed of
rotation. This type pump unit also cannot run in a dry condition.
The long rotating shaft that imparts the circular motion to drive
the down hole progressive cavity pump is driven from the surface by
a rotatary top head drive motor.
[0009] Forth, linear sucker rod pumps may be used. Linear sucker
rods use a reversible motor and servo positioners to directly
control a sucker rod using a rack and pinion mechanism. The linear
sucker rod pump mounts directly to a well head. A rigid drive rod
runs through a channel inside the rack and is suspended from the
top by a conventional rod clamp. An induction motor, coupled to the
rack and pinion mechanism through a gear box, cycles the rack up
and down to reciprocate the rod and thus pump up the oil.
[0010] Unlike the marginal stripper wells, bitumen yield rate from
oil sands is pumped as fast as possible to take advantage if the
flowing heated bitumen before it cools off and flow slows. Oil
sands are a mixture of sand, bitumen and water. Bitumen does not
flow well in its naturally occurring state. Generally, bitumen is
extracted from the oil sands through open pit mining and the deep
oil sands by injected steam recovery. A middle layer of tar sand
can be extracted by electro--thermal stripping system process. Deep
in situ thermal recovery involves drilling a well and injecting
steam to heat the bitumen thereby allowing the bitumen to flow out
of the sand and into the well bore. Conventional pumps cannot
recover bitumen from the middle tar sands between surface mining
and deep steam injection and recovery.
[0011] Similarly, sustained methane gas well dewatering operations
are generally low yield rate operations. Methane gas dewatering is
the dewatering of coal beds that contain methane. Water suppresses
the release of the methane gas because of methane's affinity for
the water molecule. In other words, in the presence of water,
methane rapidly dissolves in the water and becomes unusable. Coal
beds often have isolated (perched) pockets of water that when
breached yield a transitory high flow rate of water into a typical
dewatering well. Eventually the flow rate decreases into a
relatively stable low flow rate. The typical submersible pump is
well adapted to handle the initial high flow rate, but as the flow
rate decreases, the submersible pump begins to pump high levels of
grit and suspended particles which quickly wear out the internal
components of the submersible pump. In order to keep the water from
flooding the well, a low pump rate must be maintained (generally
under 5 gallons per minute). These low flow rates are also
insufficient to cool the typical submersible pump which uses the
pumping fluid to cool its electric motor. The conventional pumps
described above are not well suited for methane gas dewatering
operations.
SUMMARY OF THE DISCLOSURE
[0012] A short stroke piston pump for recovering oil and/or water
from marginal stripper wells, tar sands and coal beds is described
herein. The short stroke piston pump includes a motor connected to
one end of a flexible drive rod, the motor is capable of moving the
flexible drive rod in a generally up and down direction. A piston
is connected to another end of the flexible drive rod. The piston
and flexible drive rod are then disposed in a riser pipe and the
piston transports fluid up the riser pipe as the piston moves up
and down in the riser pipe. Additionally, a controller is
communicatively connected to the motor. The controller may change
the speed and direction of the motor, and may even pause the motor,
in response to a location and/or status of the drive rod within the
riser pipe.
[0013] Also disclosed herein is a method of extracting oil from
marginal stripper wells, and includes providing a short stroke
piston pump and installing the short stroke piston pump on the
marginal stripper well. The controller is programmed to vary the
speed and/or frequency of the motor based on the depth of the
marginal stripper well, the discharge pressure, the yield of the
marginal stripper well, and the viscosity of the oil in the
marginal stripper well.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] Objects, features, and advantages of the present disclosure
will become apparent upon reading the following description in
conjunction with the drawing figures, in which:
[0015] FIG. 1 is a side sectional view of a short stroke piston
pump constructed in accordance with the teachings of the
disclosure;
[0016] FIG. 2 is a close up side sectional view of the short stroke
piston pump of FIG. 1; and
[0017] FIGS. 3A-3C are side exploded views of the internal
components of the short stroke piston pump of FIG. 1.
DETAILED DESCRIPTION OF THE DISCLOSURE
[0018] FIG. 1 illustrates a short stroke piston pump 201
constructed in accordance with the teachings of the disclosure. The
short stroke piston pump 201 includes a riser pipe 200 and a valve
assembly 220 attached to one end of the riser pipe 200. The valve
assembly 220 includes a piston 230 connected to a flexible drive
rod 232. The flexible drive rod may be made of fiberglass, or any
similar flexible material. The flexible drive rod 232 extends
through a flow chamber 233 to a motor 234 which moves the piston
230 in a reciprocating normally up and down motion through the flow
chamber 233 thereby pumping liquid in a direction from the valve
assembly 220 towards the motor 234. The motor 234 is attached to
the drive rod 232 by an actuator 242. Limit switches 244 measure
travel of the actuator 242 as the motor 234 moves the actuator 242.
The limit switches 244 send signals to a controller 240 as a
portion of the actuator 242 contacts each respective limit switch
244. The controller 240 sends signals to the motor 234 based on
input from the limit switches 244 and a programmed operational
routine, thereby controlling the frequency and direction that the
motor 234 moves the actuator 242, and thus the drive rod 232 and
piston 230. The motor 234 may be a variable speed motor to move the
actuator at different speeds and/or frequencies. The motor 234 may
be electrically or pneumatically actuated. Generally, the drive
motor 234 produces a stroke length of between 10 and 30 inches.
However, shorter or longer stroke lengths may be used if required.
Further, the motor 234 preferably is one that produces less than
about five horsepower, although larger motors may be used if
required for greater depths or greater discharge pressures.
[0019] Generally, piston pumps with flexible dive rods have been
used for shallow well pumping viscous and non-viscous fluids (e.g.,
wastewater pumping at landfills, coal tar recovery of bunker C oil,
and recovery of #6 fuel oil). Such pumps were previously limited to
shallow wells because they lacked the hp and mechanical strength to
lift at the greater depths. At depths greater than about 1000 ft.,
rod stretch (or "float") becomes a significant problem, such that
the motor can become overloaded because the piston may be moving in
an upward direction for a significant amount of time (due to the
stretch) even after the motor has reversed direction and is moving
the drive rod in a downward direction. More viscous fluids present
a similar problem, especially at deeper depths. Viscous fluids,
such as oil, produce more resistance in the piston during
operation. This additional resistance magnifies the issue of drive
rod stretch. As a result, piston pumps used to pump viscous fluids,
or to pump from deep wells, tend to employ non-flexible drive rods
(e.g., steel drive rods). However, non-flexible drive rods add
significant amounts of weight and cost to the piston pump, and to
maintenance costs, as well as additional momentum-related forces
for the motor to overcome.
[0020] To overcome the drive rod float problem, the disclosed pump
201 has an electronic controller 240 that varies and controls the
speed and time of the motor 234 and thus the number of strokes per
minute of the flexible drive rod 232. For example, when pumping
viscous fluids, such as oil, the controller 240 may pause the motor
234 at a bottom of a down stroke to allow energy stored in the
flexible drive rod 232 (due to stretch) to fully unload, thereby
driving the piston 230 fully into the viscous fluid. A similar
pause of the motor at a top of an upstroke may also allow energy
stored in the drive rod 232 (from stretch) to unload. Likewise, for
very deep wells, the controller 240 may pause the motor 234 at the
bottom of the down stroke to unload any energy stored in the
flexible drive rod 232 due to the stretch. Also for deeper wells,
the controller may vary motor speed to change the speed of the
piston during the upstroke of the pump as compared to a speed of
the piston during the downstroke of the pump. During the upstroke,
additional force is exerted on the flexible drive rod 232 due to
the extra weight of the fluid being moved upwards through the flow
chamber 233. Thus, the flexible drive rod 232 may experience more
stretch during the upstroke. To counter this additional stretch,
the controller 240 may slow the motor 234 during the upstroke,
thereby allowing the flexible drive rod 232 to stretch more
gradually and reducing the stress on the flexible drive rod 232 and
the motor 234 due to drive rod stretch. In this manner, the
disclosed piston pump 201 advantageously has a lightweight,
inexpensive flexible drive rod 232, requiring less overall energy
to operate and producing less momentum issues as seen by the pump
motor 234, while still having the ability to pump viscous fluid
from deep wells (e.g., wells up to about 2000 ft. in depth).
Generally, the speed of the motor 234 may be varied, during the
upstroke and downstroke, between about 50 Hz and about 10 Hz, which
produces between approximately 27 piston strokes per minute and
approximately 5 piston strokes per minute. However, virtually any
motor speed or frequency can be programmed into the controller 240.
The motors are commanded via the controller 240, to slow down when
being turned off and to have a slow initial ramp up speed when
being turned on. This is done to eliminate any sudden stop or start
that can damage a motor gear coupling, a slip gear or break a
coupling key.
[0021] As shown in FIG. 2 limit switches 244a, 244b, 244c reverse
the motor 234 direction thereby imparting linear up-down motion to
the actuator 242. The motor 234 is mounted on top of the actuator
242 over the well head 260 and discharge tee 262. This
configuration ensures a stable, balanced, and aligned motor
assembly above the well. The actuator 242 includes a ball screw
242a that is connected to a lower actuator tube 242b. A lower limit
switch 244c and a middle limit switch 244b normally reverse the
motor 234 to keep a ball screw nut 264 (see FIG. 3B) that is
threadedly attached to the ball screw 242a between the lower limit
switch 244c and the middle limit switch 244b. A top limit switch
244a is a safety mechanism to reverse the motor should the middle
limit switch 244b fail or in the event that the ball screw nut 264
coasts past the middle limit switch 244b when the motor 234 is
turned off. The motor 234 always begins in the retract direction
because gravity may pull the ball screw nut 264 down to the bottom
of the stroke when the motor 234 is turned off.
[0022] FIGS. 3A-3C show a side exploded view of the short stroke
piston pump of FIGS. 1 and 2. The ball screw nut 264 is also
attached to the lower actuator tube 242b that moves up and down
with the ball screw nut 264 as the ball screw 242a turns. A bearing
mount 274 houses bearings and attaches the ball screw 242a to the
motor 234. The lower actuator tube 242b extends and retracts
outside the bottom of a landing plate 276 and connects to a drive
rod 232 (FIG. 1). The landing plate 276 is sealed by a rod seal 278
to ensure that no dirt, dust or liquid is drawn upward into the
ball screw 264. Below the landing plate 276 is a stuffing box 280
that includes more seals and/or wipers to clean the lower actuator
tube 242b of any residue. By altering the thread on the ball screw
242a, the pump 201 may be configured for faster or slower pump
rates. For example, a thread configuration that produces 1 inch of
travel per turn of the ball screw 242a will pump faster than a
thread configuration that produces 1 inch of thread for every two
turns of the ball screw 242a. However, the thread configuration
that produces 1 inch of travel per turn will create a greater load
on the motor 234 than the thread configuration that produces 1 inch
of travel per two turns. Examples of loads and pump rates of
different motor and stroke length combinations are summarized in
the table below.
TABLE-US-00001 TABLE 1 Limit 10 10 10 10 10 10 20 10 10 10 Switch
Separation (in) Stroke 14 14 14 14 14 14 24 14 14 14 Length (in)
Load (lbs) 206 406 502 545 550 598 740 808 993 1187 Motor HP 0.5 1
1.5 1.5 1.5 1.5 2 2 3 3 TDH 385 800 1000 1000 1100 1100 1500 1500
1500 1800 Rod 0.95 4.12 6.44 3.62 7.80 4.38 14.50 8.15 3.62 5.22
Stretch (in) Gallons 0.06 0.04 0.03 0.04 0.03 0.04 0.04 0.02 0.04
0.04 per stroke Strokes 18.00 23.85 31.28 22.73 38.23 24.57 25.19
40.97 22.87 27.24 per gallon Barrel per 38.05 28.73 21.90 30.13
17.92 27.88 17.48 16.72 29.95 25.15 day
[0023] As discussed earlier, marginal stripper wells have a
relatively low yield of oil. In some cases, the yield of a stripper
well may be as little as five barrels of oil per week, or less.
Large heavy iron jack pumps, as geared to high yield wells, do not
have the ability to reduce their pumping capacity to capture such
low yields of oil, without the potential of over-pumping the
formation and pumping water instead of oil. This pumped water then
needs to either be treated and discharged at surface, or sent back
down an injection well, where then yet more cost is incurred to
pump and transfer this water.
[0024] One advantage of the disclosed pump is that the controller
240 can adapt pumping capacity to the yield of the particular well.
In other words, the controller 240 may operate the motor 234 at a
speed that pumps oil out, makes less water of the marginal stripper
well at a rate that substantially matches the inflow yield of the
marginal stripper well. In doing so, the pump 201 withdraws less
water and foreign material (i.e., sand) because the pump rate is
matched to the rate at which oil is filling in the well. Thus, the
disclosed pump 201 requires less maintenance and produces less wear
due to foreign objects being pumped through the flow chamber 233.
Essentially, the pump 201 is customizable to each and every
individual marginal stripper well, e.g. with respect to yield,
depth, and discharge pressure. Furthermore, the flexible nature of
the drive rod 232 and riser pipe 200 allow the pump 201 to be used
in well bores that are not entirely vertical (e.g., a well bore
that changes direction to avoid subterranean features), or one
having a casing shift.
[0025] Yet another advantage of the pump 201 is that the relatively
light weight of the drive rod 232 gives the pump 201 low inertia.
This means that the pump 201 is easily stopped and started.
Moreover, this low inertia enables the motor 234 to vary its speed
and even pause pumping at any time, thus enabling the pump 201 to
overcome problems due to drive rod 232 stretch, yield over-pumping,
and pumping on command.
[0026] Still another advantage of the pump 201 is that the pump 201
can generally be installed with a work team of as few as three.
This is due again to the lightweight nature of the pump 201. This
reduction in manpower results in a lower initial capital expense
and thus causes more marginal stripper wells to become economically
feasible to pump. This thus eliminates the need for an expensive
so-called "makeover rig" to install the down hole pump, and to set
up the pump jack over the well.
[0027] Typically, a marginal stripper well is identified and
analyzed for its potential yield. Once the potential yield is
determined a cost estimate is performed based on the cost of the
pump 201 and the energy required to run the pump 201 for a given
oil yield. The cost estimate is then compared to an expected profit
based on the estimated yield of the marginal stripper well. Once an
economically feasible marginal stripper well is identified, an
installation team installs the pump 201 on the marginal stripper
well. A technician adjusts the controller 240 to maintain a motor
setting conforming to the estimated yield of the marginal stripper
well. Additionally, the technician calculates the amount of drive
rod stretch based on the marginal stripper well depth and programs
the controller 240 to compensate for the drive rod stretch. Once
the initial set up is complete, the technician may monitor the pump
201 (even remotely if desired) to analyze the true yield of the
marginal stripper well. Adjustments may be made (again remotely if
desired, by telemetrics) on a periodic basis as the yield
fluctuates.
[0028] Although certain pumps have been described herein in
accordance with the teachings of the present disclosure, the scope
of the appended claims is not limited thereto. On the contrary, the
claims cover all embodiments of the teachings of this disclosure
that fairly fall within the scope of permissible equivalents.
* * * * *