Note: Descriptions are shown in the official language in which they were submitted.
CA 02441307 2003-09-16
WO 02/086322 PCT/US02/12751
FLUID CONTROLLED PUMPING SYSTEM AND METHOD
TECHNICAL FIELD OF THE INVENTION
This invention relates in general to the field of fluid pumping systems and,
more
particularly, to a fluid controlled pumping system and method.
BACKGROUND OF THE INVENTION
Pumping units are used in a variety of applications for compressing, raising,
or
transferring fluids. For example, pumping units may be used in municipal water
and
1 o sewage service applications, mining andlor hydrocarbon exploration and
production
applications, hydraulic motor applications, and consumer product manufacturing
applications. Pumping units, such as progressive cavity pumps, centrifugal
pumps, and
other types of pumping devices, are generally disposed within a fluid and are
used to
compress or increase the pressure of the fluid, raise the fluid between
different elevations,
or transfer the fluid between various destinations.
Conventional pumping units, however, suffer several disadvantages. For
example,
conventional pumping units generally require some form of lubrication to
remain
operational. For instance, a progressive cavity pump generally includes a
rotor disposed
within a rubber stator. In operation, a rotational force is imparted to the
rotor, thereby
2 0 producing a corkscrew-like effect between the rotor and the stator to lift
the fluid from one
elevation to another. W the case of the progressive cavity pump, friction
caused by the
rotation of the rotor relative to the stator without fluid lubrication
oftentimes causes the
progressive cavity pump to fail within a relatively short period of time.
Generally, the
fluid that is being pumped provides the required lubrication. However,
variations in the
2 5 fluid level proximate to an inlet of the pumping unit may result in an
absence of fluid
lubrication for the pumping unit. Thus, maintaining adequate fluid lubrication
at the
pumping unit is critical for the performance and longevity of pumping
operations.
Additionally, in centrifugal pumping applications, an absence of the fluid to
be pumped
may cause cavitation.
CA 02441307 2003-09-16
WO 02/086322 PCT/US02/12751
2
SUMMARY OF THE INVENTION
Accordingly, a need has arisen for an improved pumping system that provides
increased control of fluid lubrication of the pumping unit. The present
invention provides
a fluid controlled pumping system and method that addresses shortcomings of
prior
pumping systems and methods.
According to one embodiment of the present invention, a fluid controlled
pumping
system includes a pumping unit disposed within a fluid cavity. The pumping
unit includes
a passage extending to a head of the pumping unit. The system also includes a
pressure
source coupled to the passage and operable to force a fluid outwardly from the
head of the
pumping unit through the passage. The system also includes a pressure sensor
coupled to
the passage and operable to determine a fluid pressure within the passage. The
system
further includes a controller coupled to the pumping unit and operable to
regulate an
operating parameter of the pumping unit in response to the fluid pressure.
According to another embodiment of the present invention, .a method for fluid
controlled pumping includes providing a pumping unit disposed within a fluid
cavity. The
pumping unit includes a passage extending to a head of the pumping unit. The
method
also includes forcing a fluid outwardly from the head of the pumping unit
through the
passage and determining a fluid pressure within the passage. The method also
includes
automatically regulating an operating parameter of the pumping unit in
response to the
2 o fluid pressure.
According to another embodiment of the present invention, a fluid controlled
pumping system includes a pumping unit disposed within a fluid cavity. The
pumping
unit includes an inlet operable to receive a fluid to be pumped from the fluid
cavity. The
system also includes a valve slidably coupled to the pumping unit. The valve
includes a
2 5 passage for receiving pump fluid from the pumping unit. The valve is
further operable to,
in response to a decreasing fluid level within the fluid cavity, move relative
to the
pumping unit to align a passage of the valve with a port of the pumping unit
to recirculate
the pumped fluid to the inlet of the pump.
According to another embodiment of the present invention, a method for fluid
level
3 0 controlled pumping includes providing a progressive cavity pump disposed
within a fluid
cavity. The pump includes a stator/rotor portion for pumping fluid disposed in
the fluid
cavity. The stator/rotor portion includes an inlet and an outlet. The method
also includes
CA 02441307 2003-09-16
WO 02/086322 PCT/US02/12751
3
providing a valve coupled to the pump. The valve is operable to receive the
fluid from the
outlet of the stator/rotor portion. The method further includes automatically
recirculating
the fluid from the outlet to the inlet via the valve in response to a decrease
in a fluid level
within the fluid cavity.
According to yet another embodiment of the present invention, a fluid level
controlled pumping system includes a progressive cavity pump disposed within a
fluid
cavity. The pump includes a stator/rotor portion for pumping a fluid disposed
within the
fluid cavity. The stator/rotor portion of the pump includes an inlet and an
outlet. The
system also includes a valve coupled to the pump and disposed in communication
with the
outlet. The valve is operable to recirculate the fluid from the outlet to the
inlet in response
to a decrease in a fluid level in the fluid cavity.
The invention provides several technical advantages. ~ For example, in one
embodiment of the present invention, the system monitors the fluid pressure
within the
fluid cavity which corresponds to a level of the fluid within the fluid
cavity. Based on the
fluid pressure, the system controls the operating parameters of the pumping
unit to ensure
proper fluid lubrication during operation. Thus, as the fluid level decreases
within the
fluid cavity, the operating parameters of the pumping unit may be modified.
For example,
in response to a decrease in the fluid level within the fluid cavity, the
operating speed of
the pumping unit may also be decreased, thereby maintaining a substantially
constant fluid
2 0 level within the fluid cavity to provide required pumping unit
lubrication. Additionally,
operation of the pumping unit may also be ceased based on the fluid level
within the fluid
cavity to substantially prevent operation of the pumping unit absent fluid
lubrication.
Another technical advantage of the present invention includes providing a
fluslung
mechanism for substantially preventing a build-up of materials at the inlet of
the pumping
2 5 unit. For example, a progressive cavity pump may include an internal
passage extending
downwardly within a rotor of the pump and having an outlet disposed proximate
to the
inlet of the pump. A fluid may be provided downwardly within the passage and
outwardly
from the outlet of the passage to flush material accumulation build-up from
the inlet of the
pump and maintain material suspension within the pumped fluid if desired.
3 o The invention additionally provides several technical advantages. For
example, in
one embodiment of the present invention, fluid lubrication of the pumping unit
is
maintained by recirculating the pumped fluid to the inlet of the pumping unit
in response
CA 02441307 2003-09-16
WO 02/086322 PCT/US02/12751
4
to a change in a fluid level within the fluid cavity. For example, according
to one
embodiment of the present invention, a valve is disposed proximate the pumping
unit to
recirculate pumped fluid back to the inlet of the pumping unit. Thus, as the
fluid level
decreases within the fluid cavity, the valve recirculates the pumped fluid to
the inlet of the
pumping unit to substantially prevent operation of the pumping unit absent
fluid
lubrication. In one embodiment, the valve may be slidably coupled to the
pumping unit,
thereby providing movement of the valve relative to the pumping unit in
response to
changes in the fluid level within the fluid cavity.
Another technical advantage of the present invention includes increased
reliability
of the pumping unit without necessitating costly user intervention. For
example,
according to one embodiment of the invention, a valve is slidably coupled to
the pumping
unit, thereby providing upward and downward movement of the valve in response
to
variations in a fluid level within a fluid cavity. The valve automatically
provides
recirculation or the return of the pumped fluid to the inlet of the pumping
unit to ensure
lubrication of the pumping unit in response to decreasing fluid levels within
the fluid
cavity.
Other technical advantages will be readily apparent to one skilled in the art
from
the following figures, descriptions, and claims.
CA 02441307 2003-09-16
WO 02/086322 PCT/US02/12751
BRIEF DESCRIPTION OF THE DRAWINGS
For a more complete understanding of the present invention and the advantages
thereof, reference is now made to the following descriptions taken in
connection with the
accompanying drawings in which:
5 FIGURE 1 is a diagram illustrating a fluid controlled pumping system in
accordance with an embodiment of the present invention;
FIGURE 2 is a diagram illustrating a fluid controlled pumping system in
accordance with another embodiment of the present invention;
FIGURE 3 is a diagram illustrating the fluid controlled pumping system
illustrated
in FIGURE 2 after a change in a fluid level within a fluid cavity in
accordance with an
embodiment of the present invention; and
FIGURE 4 is a flow chart illustrating a method for fluid level controlled
pumping
in accordance with an embodiment of the present invention.
DETAILED DESCRIPTION OF THE DRAWINGS
FIGURE 1 is a diagram illustrating a fluid controlled pumping system 10 in
accordance with an embodiment of the present invention. In the embodiment of
FIGURE
1, the system 10 is illustrated in a mining or hydrocarbon production
application; however,
it should be understood that the system 10 may also be used in other pumping
2 0 applications. The system 10 includes a pumping unit 12 extending into a
fluid cavity 13.
The fluid cavity 13 generally includes a fluid to which a compressing,
raising, or
transferring operation is to be performed. Thus, in the illustrated
embodiment, the
pumping unit 12 extends downwardly from a surface 14 into a well bore 16. In
this
embodiment, pumping unit 12 comprises a progressive cavity pump 1 ~; however,
it should
2 5 be understood that other types of pumping units 12 may be used
incorporating the
teachings of the present invention.
Pump 18 includes a base portion 20 disposed on the surface 14 and a
stator/rotor
portion 22 disposed within the well bore 16. Stator/rotor portion 22 includes
a stator 24
coupled to an interior surface 26 of a housing 28. Stator/rotor portion 22
also includes a
3 0 rotor 30 disposed within the stator 24 such that rotation of the rotor 30
relative to the stator
24 produces a corkscrew-like effect, thereby pumping or lifting a fluid 32
disposed within
the cavity 13, or well bore 16, to the surface 14. It should be understood
that, in this
CA 02441307 2003-09-16
WO 02/086322 PCT/US02/12751
6
embodiment, the fluid 32 may include water, hydrocarbon compositions, drilling
mud,
drilling cuttings, and other substances generally lifted to the surface 14
from the well bore
16. However, the fluid 32 may comprise other substances generally encountered
in the
particular pumping application.
In operation, a suction end 34 of the stator/rotor portion 22 is disposed
within the
well bore 16 such that rotation of the rotor 30 relative to the stator 24
draws the fluid 32
upwardly through an inlet 36 formed between the rotor 30 and the stator 24.
The fluid 32
travels upwardly through the stator/rotor portion 22 and exits a discharge end
38 of the
stator/rotor portion 22 through an outlet 40 formed between the stator 24 and
the rotor 30.
l0 The fluid 32 travels upwardly within an annulus 42 formed between the
housing 28 and a
drive shaft 44. A lower end 46 of the drive shaft 44 is coupled to an upper
end 48 of the
rotor 30 to provide rotational movement of the rotor 30 relative to the stator
24. The fluid
32 traveling upwardly through the annulus 42 is directed outwardly from
annulus 42 to a
mud pit or other location (not explicitly shown) through a discharge port 50.
For example,
the fluid 32 may be directed through discharge port 50 to a separator (not
explicitly
shown) for separating hydrocarbons and/or other substances from water.
However, it
should be understood that the fluid 32 may also be directed through discharge
port 50 to
other suitable processing systems.
The well bore 16 also includes a discharge port 52 for directing gas or other
2 0 substances outwardly from well bore 16. For example, a gas disposed within
the well bore
16 may travel upwardly through an annulus 54 formed between the housing 28 and
both
the well bore 16 and a housing 56 of the base portion 20. Thus, gases within
the well bore
16 may be directed upwardly toward the surface 14 and discharged through port
52 to be
flared or to accommodate other suitable processing requirements.
2 5 As illustrated in FIGURE 1, the pumping unit 12 also includes a hollow
passage 60
extending downwardly through drive shaft 44 and rotor 30. Passage 60 includes
an open
end 62 disposed proximate the suction end 34 of the stator/rotor portion 22
such that a
depth 64 of the fluid 32 within the well bore 16 relative to the pumping unit
12 may be
monitored. The use of the passage 60 will be described in greater detail
below.
3 0 System 10 also includes a pneumatic pressure source 72, a pressure sensor
74, a
controller 76, and a drive motor 78. Pressure source 72 is coupled to the
passage 60
through an upper end 80 of the pumping unit 12 for directing a pressurized
fluid
CA 02441307 2003-09-16
WO 02/086322 PCT/US02/12751
7
downwardly within the passage 60. Pressure source 72 may include carbon
dioxide,
nitrogen, air, methane, or other suitable pressurized fluids. Pressure sensor
74 is also
coupled to the passage 60 for measuring the fluid pressure within the passage
60.
In operation, the pressure source 72 provides a pressurized fluid downwardly
within the passage 60 such that a relatively small and controlled amount or
volume of the
pressurized fluid exits the open end 62 of the passage 60, as indicated
generally at 90. For
example, the pressure source 72 may be maintained at a pressure significantly
greater than
a pressure of the fluid 32 within the well bore 16, and an orifice metering
valve 82 may be
coupled to the pressure source 72 such that the friction pressure becomes
generally
l0 negligible. However, other suitable methods and devices may also be used to
maintained
a controlled amount or volume of the pressurized fluid exiting the open end 62
of the
passage 60.
The pressure sensor 74 is used to measure the pressure within the passage 60
required to dispel the pressurized fluid from the open end 62 of the passage
60. As
illustrated in FIGURE 1, the pressure required to dispel the pressurized fluid
outwardly
from the open end 62 of the passage 60 generally corresponds to the level or
depth 64 of
the fluid 32 proximate the inlet 36 of the pumping unit 12. Therefore, the
pressure within
the passage 60 may be used to determine the depth 64 of the fluid 32 proximate
the inlet
36 of the pumping unit 12.
2 0 As further illustrated in FIGURE l, the pressure sensor 74 is coupled to
the
controller 76. The controller 76 may comprise a processor, mini computer,
workstation, or
other type of processing device for receiving a signal from the pressure
sensor 74
corresponding to the pressure within the passage 60. The signals received from
the sensor
74 by the controller 76 may comprise a continuous data stream or may comprise
periodic
2 5 data signals. The controller 76 receives the signals from the sensor 74
and monitors the
fluid pressure within the passage 60. Based on the pressure within the passage
60, the
controller 76 regulates the operating parameters of the pumping unit 12.
For example, as illustrated in FIGURE 1, the controller 76 is coupled to the
drive
motor 78 to control the operating parameters of the pumping unit 12. As
illustrated in
3 0 FIGURE 1, the drive motor 78 imparts a rotational force to the drive shaft
44 via a belt 92
coupled between the drive motor 78 and the drive shaft 44 proximate the upper
end 80 of
the pumping unit 12 to rotate the rotor 30 relative to the stator 24. Thus,
the controller 76
CA 02441307 2003-09-16
WO 02/086322 PCT/US02/12751
8
controls the rotational force imparted by the drive motor 78 based on the
pressure signal
received from the pressure sensor 74, thereby controlling the fluid 32 flow
rate to the
surface 14. For example, in operation, the drive motor 78 receives a control
signal from
the controller 76 to regulate the rotational force imparted to the drive shaft
44 by the drive
motor 78.
Thus, in operation, the operating parameters of the pumping unit 12 are
modified
in response to changes in the amount of fluid 32 within the well bore 16 to
substantially
prevent operation of the pumping unit 12 in a "dry" or unlubricated condition.
For
example, as illustrated in FIGURE 1, pressure source 72 provides a pressurized
fluid
downwardly within the passage 60 so that a relatively small and controlled
amount or
volume of the pressurized fluid exits the open end 62 of the passage 60
proximate the
suction end 34. In response to a change in the depth 64 of the fluid 32 within
the well bore
16, the pressure within the passage 60 required to dispel the pressurized
fluid outwardly
from the open end 62 of the passage 60 also varies. Based on the pressure
change within
the passage 60, controller 76 regulates the operating parameters of the
pumping unit 12 via
drive motor 78. Thus, as the depth 64 of the fluid 32 within the well bore 16
decreases,
the pressure within the passage 60 required to dispel the pressurized fluid
outwardly from
the open end 62 also correspondingly decreases. In response to a decrease in
the pressure
within the passage 60, controller 76 automatically reduces the rate of
rotation of the drive
2 0 shaft 44 provided by the drive motor 78, thereby resulting in a decrease
in the flow rate of
fluid 32 removed from the well bore 16. Thus, the rate of rotation of the
drive shaft 44
may be reduced or ceased in response to a decrease in the level of the fluid
32 within the
well bore 16, thereby reducing the rate of fluid 32 flow upwardly out of the
well bore 16
and substantially preventing the operation of the pumping unit 12 absent
adequate
2 5 lubrication. Additionally, by regulating the operating parameters of the
pumping unit 12
based on the fluid 32 level within the well bore 16, the present invention
also provides a
means to maintain a substantially constant fluid 32 level within the well bore
16.
Correspondingly, system 10 may also be used to increase the rate of rotation
of the
drive shaft 44 in response to increases in the depth 64 of the fluid 32 in the
well bore 16,
3 0 thereby increasing the fluid 32 flow rate from the well bore 16. For
example, as the depth
64 of the fluid 32 increases within the well bore 16, the pressure required to
dispel the
fluid outwardly from the open end 62 of the passage 60 also increases. In
response to the
CA 02441307 2003-09-16
WO 02/086322 PCT/US02/12751
9
increase in pressure within the passage 60, the controller 76 regulates the
drive motor 78
to provide additional rotational force to the drive shaft 44, thereby
providing increased
pumping volume of the fluid 32 to the surface 14.
Thus, the present invention provides increased control of the pumping of fluid
32
from the well bore 16 to the surface 14 based on an amount or depth 64 of the
fluid 32
within the well bore 16. As the depth 64 of the fluid 32 increases or
decreases, the
controller 76 regulates the operating parameters of the pumping unit 12 via
the drive
motor 78, thereby causing a corresponding increase or decrease, respectively,
of the
rotational speed of the drive shaft 44. Therefore, the present invention may
be used to
provide increased pumping of the fluid 32 in response to increased levels of
the fluid 32
within the well bore 16 and/or a decrease or cessation of the pumping of the
fluid 32 from
the well bore 16 in response to decreasing amounts of fluid 32 within the well
bore 16.
The present invention may also provide flushing or mixing of the fluid 32
within
the fluid cavity 13 to substantially prevent or eliminate material build-up at
the inlet 36 of
the pumping unit 12. For example, a solenoid valve 96 or other suitable device
may be
used to provide periodic fluid pressure bursts downwardly through the passage
60 and
outwardly proximate to the suction end 34 of the pumping unit 12 to
substantially prevent
material accumulation at the inlet 36 and maintain material suspension within
the fluid 32.
FIGURE 2 is a diagram illustrating a fluid controlled pumping system 100 in
2 0 accordance with another embodiment of the present invention, and FIGURE 3
is a
diagram illustrating the system 100 illustrated in FIGURE 2 after a decrease
in a fluid 102
level within a well bore 104 in accordance with an embodiment of the present
invention.
In this embodiment, system 100 includes a pumping unit 106 disposed within the
well
bore 104 for pumping the fluid 102 within the well bore 104 to the surface.
The pumping
2 5 unit 106 illustrated in FIGURES 2 and 3 comprises a progressive cavity
pump 108.
However, it should be understood that other types of pumping units 106 may
also be used
in accordance with the teachings of the present invention.
As described above in connection with FIGURE 1, the progressive cavity pump
108 includes a stator/rotor portion 110 for lifting the fluid 102 within the
well bore 104 to
3 0 the surface. For example, as illustrated in FIGURES 2 and 3, the
stator/rotor portion 110
includes a rotor 112 coupled to a drive shaft 114 rotatable within a stator
116 of the pump
108. Thus, rotation of the rotor 112 relative to the stator 116 draws the
fluid 102 into an
CA 02441307 2003-09-16
WO 02/086322 PCT/US02/12751
inlet 118 of the stator/rotor portion 110 such that the corkscrew-like
movement of the rotor
112 relative to the stator 116 lifts the fluid 102 through the stator/rotor
portion 110 and
dispels the fluid 102 outwardly from an outlet 120 of the stator/rotor portion
110. The
fluid 102 then travels upwardly from a discharge end 122 of the stator/rotor
portion 110
5 via an annulus 124 formed between the drive shaft 114 and a housing 126 of
the pumping
unit 106 to the surface. '
In tlus embodiment, system 100 also includes .a valve 140 disposed about the
housing 126 of the pumping unit 106 and a check valve 142 disposed proximate a
suction
end 144 of the pumping unit 106. Valve 140 is slidably coupled to the housing
126 of the
1 o pumping unit 106 such that variations in the fluid 102 level within the
well bore 104 cause
corresponding upward and downward movement of the valve 140 relative to the
pumping
unit 106. For example, in this embodiment, valve 140 includes internal
chambers 146 that
may be filled with a fluid, foam, or other substance generally having a
density less than a
density of the fluid 102 such that the valve 140 floats in the fluid 102
relative to the
pumping unit 106. Thus, for example, the internal chambers 146 may be filled
with
nitrogen, carbon dioxide, foam, or other suitable fluids or substances
generally having a
density less than a density of the fluid 102. In the embodiment illustrated in
FIGURES 2
and 3, two internal chambers 146 are illustrated; however, it should be
understood that a
fewer or greater number of internal chambers 146 may be used to obtain
floatation of the
2 o valve 140 relative to the pumping unit 106. The valve 140 may be
constructed from two
or more components secured together about the pumping unit 106, or the valve
140 may
be constructed as a one-piece unit. For example, the checlc valve 142 may be
removable
coupled to the housing 126 (not explicitly shown) to accommodate placement of
the valve
140 about the pumping unit 106. However, it should be understood that other
suitable
2 5 assembly methods may be used to position the valve 140 relative to the
pumping unit 106.
In the embodiment illustrated in FIGURES 2 and 3, housing 126 includes
integrally formed upper stops 150 and lower stops 152. Stops 150 and 152
restrict upward
and downward movement of the valve 140 to predetermined locations relative to
the
pumping unit 106 in response to variations in the fluid 102 level within the
well bore 104.
3 0 For example, as illustrated in FIGURE 2, as the level of the fluid 102
within the well bore
104 increases, the valve 140 floats upwardly relative to the pumping unit 106
until an
upper end 154 of the valve 140 reaches the stop 150. Similarly, referring to
FIGURE 3, in
CA 02441307 2003-09-16
WO 02/086322 PCT/US02/12751
11
response to a decrease in the level of the fluid 102 within the well bore 104,
the valve 140
floats downwardly relative to the pumping unit 106 until a lower end 156 of
the valve 140
reaches stops 152. Thus, as will be described in greater detail below, stops
150 and 152
are positioned on pumping unit 106 to position the valve 140 relative to the
pumping unit
106 in predetermined locations to facilitate recirculation of the pumped fluid
102.
As illustrated in FIGURES 2 and 3, the valve 140 includes a passage 160
extending from an upper end 162 of the valve 140 to a lower end 164 of the
valve 140.
The passage 160 provides a communication path for recirculating all or a
portion of the
pumped fluid 102 from the discharge end 122 of the stator/rotor portion 110 to
the inlet
118 of the stator/rotor portion 110 in response to a decreasing fluid 102
level within the
well bore 104. The recirculation of the pumped fluid 102 will be described in
greater
detail below in connection with FIGURE 3.
System 100 also includes a locking system 170 for releasably securing the
valve
140 in predetermined positions relative to the pumping unit 106. In this
embodiment, the
locking system 170 includes a locking element 172 biased inwardly relative to
the valve
120 towards the housing 126 via a spring 174. The housing 126 includes
integrally
formed recesses 176 and 178 configured to receive the locking element 172 to
releasably
secure the valve 140 in the predetermined positions relative to the pumping
unit 106. For
example, as illustrated in FIGURE 2, in response to an increase in the level
of fluid 102
2 0 within the well bore 104, the valve 140 floats upwardly relative to the
pumping unit 106 to
an upwardly disposed position where the locking system 170 releasably secures
the valve
140. As will be described in greater detail below, the locking system 170
substantially
prevents undesired movement of the valve 140 relative to the pumping unit 106
as a result
of fluid 102 turbulence within the well bore 104 or minor fluid 102 variations
within the
2 5 well bore 104. The locking system 170 also provides a mechanism for
securing the valve
140 in a desired position relative to the pumping unit 106 to substantially
reduce the power
required for operating the pumping unit 106.
As illustrated in FIGURE 3, in response to a decrease in the level of fluid
102 in
the well bore 104, the valve 140 moves downwardly relative to the pumping unit
106 to a
3 0 downwardly disposed position where locking system 170 releasably secures
the valve 140.
The locking system 170 may be configured such that a weight of the valve 140
unsupported by the fluid 102 is greater than a force of the spring 174
directed inwardly,
CA 02441307 2003-09-16
WO 02/086322 PCT/US02/12751
12
thereby causing a release of the valve 140 from the upwardly disposed position
in
response to a decrease in the level of fluid 102 within the well bore 104.
Thus, as will be
described in greater detail below, the locking system 170 releasably secures
the valve 140
in predetermined positions relative to the pumping unit 106 to facilitate
recirculation of the
pumped fluid 102 or to cease the recirculation of the pumped fluid 102.
As illustrated in FIGURES 2 and 3, the pumping unit 106 includes a port 190
formed in a wall 192 of the housing 126 proximate to the discharge end 122 of
the
stator/rotor portion 110. The pumping unit 106 also includes a port 194 formed
in the wall
192 of the housing 126 proximate to the inlet 118 of the stator/rotor portion
110. Seals
198, such as O-ring elastomer seals or other suitable sealing members, are
disposed on
each side of ports 190 and 194 to prevent undesired leakage of the fluid 102
about the
ports 190 and 194 relative to the valve 140.
The check valve 142 includes a ball or sphere 200 disposed within an internal
area
202 of the check valve 142 sized greater than a size of an inlet 204 of the
check valve 142
such that the sphere 200 may be received by a seating area 206 of the check
valve 142 to
substantially prevent passage of the fluid 102 through the inlet 204 from the
internal area
202. However, it should be understood that other suitable shapes, such as
ovoid or
otherwise, or devices, such as a flapper or otherwise, may be used to
substantially prevent
passage of the fluid 102 through the inlet 204 from the internal area 202. As
will be
2 0 described in greater detail below, the check valve 142 is disposed
proximate the inlet 118
of the stator/rotor portion 110 of the pumping unit 106 to direct the
recirculated fluid 102
to the inlet 118.
In operation, a generally high level, or an increase in the level, of the
fluid 102
within the well bore 104 causes upward movement of the valve 140 relative to
the
2 5 pumping unit 106, as illustrated in FIGURE 2. The locking system 170
releasably secures
the valve 140 in the upwardly disposed position such that the passage 160 of
the valve 140
is misaligned with the ports 190 and 194, thereby preventing recirculation of
the fluid 102
discharged from the outlet 120 of the stator/rotor portion 110. Thus, in
operation, rotation
of the rotor 112 relative to the stator 116 draws the fluid 102 inwardly
through inlet 204 of
3 0 the check valve 142 and into the internal area 202 of the check valve 142.
The fluid 102 is
further drawn into the inlet 118 of the stator/rotor portion 110 and is
discharged from the
outlet 120 as described above. In the upwardly disposed position, the passage
160 of the
CA 02441307 2003-09-16
WO 02/086322 PCT/US02/12751
13
valve 140 is not in alignment with the port 190, thereby allowing the pumped
fluid 102 to
travel upwardly to the surface via the annulus 124. The locking system 170
releasably
secures the valve 140 in the upwardly disposed position to prevent undesired
movement of
the valve 140 in response to minor fluctuations or turbulence in the level of
fluid 102
within the well bore 104. Additionally, the stops 150 prevent extended upward
movement
of the valve 140 and accommodate engagement of the locking system 170.
As the level of the fluid 102 in the well bore 104 decreases, as illustrated
in
FIGURE 3, the valve 140 travels downwardly relative to the pumping unit 106
where the
locking system 170 releasably secures the valve 140 in the downwardly disposed
position.
In the valve 140 position illustrated in FIGURE 3, an inlet 208 of the passage
160 is
aligned with the port 190, thereby receiving all or a portion of the pumped
fluid 102 from
the discharge end 122 of the stator/rotor portion 110 into the passage 160.
Additionally, in
the downwardly disposed valve 140 position illustrated in FIGURE 3, an outlet
210 of the
passage 160 is aligned with the port 194, thereby communicating the fluid
within the
passage 160 into the internal area 202 of the check valve 142 and inlet 118.
As illustrated in FIGURE 3, the reduced flow rate of the fluid 102 upwardly to
the
surface causes the sphere 200 to move downwardly and seat against the seating
area 206
of the check valve 142, thereby substantially preventing the recirculated
fluid 102 received
through the port 194 from exiting the inlet 204. The locking system 170,
therefore,
2 0 provides positive positioning of the valve 140 in either am open or closed
position to
provide or cease, respectively, fluid 102 recirculation and substantially
reduce or eliminate
modulation of the valve 140 relative to the pumping unit 106. Additionally,
the locking
system 170 substantially reduces the power required to operate the pumping
unit 106, for
example, the power required to rotate the rotor 112, by releasably securing
the valve 140
2 5 in a fully open position, thereby resulting in recirculation of the fluid
102.
Thus, in response to a decrease in the level of the fluid 102 within the well
bore
104, the valve 140 moves downwardly relative to the pumping unit 106 to
recirculate all
or a portion of the pumped fluid 102 from the discharge end 122 of the
stator/rotor portion
110 back to the inlet 118 of the stator/rotor portion 110, thereby providing a
continuous
3 0 loop of fluid 102 flow to the inlet 118 to substantially prevent operation
of the pumping
unit 106 in a "dry" or unlubricated condition. The passage 160 of the valve
140 provides a
fluid communication path between the discharge end 122 and the inlet 118 in
the
CA 02441307 2003-09-16
WO 02/086322 PCT/US02/12751
14
downwardly disposed position illustrated in FIGURE 3, thereby recirculating
the pumped
fluid 102 to the inlet 118 of the stator/rotor portion 110 in response to
decreasing fluid 102
levels within the well bore 104. The passage 160 and ports 190 and 194 may be
sized to
recirculate all or a portion of the fluid 102.
Similarly, as the fluid 102 level within the well bore 104 increases, the
valve 140
travels upwardly relative to the pumping unit 12 to the upwardly disposed
position
illustrated in FIGURE 2. As described above, the locking system 170 may be
configured
such that the increasing fluid 102 level within the well bore 104 causes the
valve 140 to
create an upwardly directed force greater than the normal inwardly directed
force from the
1 o spring 174, thereby releasing the valve 140 from the downwardly disposed
position. As
the valve 140 travels or floats upwardly relative to the pumping unit 106, the
passage 160
becomes misaligned from the ports 190 and 192, thereby ceasing the
recirculation of the
fluid 102 to the inlet 118. The seals 198 substantially prevent any undesired
fluid 102
flow through the ports 190 and 192. Thus, upward directed movement of the
valve 140
relative to the pumping unit 106 redirects the pumped fluid 102 upwardly to
the surface.
Thus, the present invention provides a fluid level controlled pumping system
that
automatically recirculates pumped fluid 102 to the inlet 118 of the pumping
unit 106 in
response to variations in the level of fluid 102 within the well bore 104.
Therefore, the
present invention provides greater reliability than prior pumping systems by
maintaining
2 0 lubrication of the pumping apparatus during decreased fluid levels within
a well bore,
thereby increasing the longevity of the pumping apparatus. Additionally, the
present
invention operates independently of manual intervention by an operator or
user, thereby
providing increased reliability and ease of use.
FIGURE 4 is a flowchart illustrating a method for fluid level controlled
pumping
2 5 in accordance with an embodiment of the present invention. The method
begins at step
200, where the pumping unit 12 is disposed within the well bore 16. As
described above,
the pumping unit 12 may comprise a progressive cavity pump 18 or other
suitable type of
pumping unit. At step 202, the pressure source 72 is used to force a
controlled volume of
fluid downwardly into the well bore via the passage 60. As described above, in
the
3 0 progressive cavity pump 18 illustrated in FIGURE 1, the pressurized fluid
is forced
downwardly through the rotor 30 via the passage 60. However, the passage 60
may be
CA 02441307 2003-09-16
WO 02/086322 PCT/US02/12751
otherwise located or configured relative to the pumping unit 12 such that the
end 62 of the
passage 60 is disposed proximate to the suction end 34 of the pumping unit 12.
At step 204, the pressurized fluid is dispelled outwardly from the end 62 of
the
passage 60 proximate to the suction end 34 of the pumping unit 12. At step
206, the
5 controller 76 monitors the pressure within the passage 60 via signals
received from the
sensor 74. As described above, the sensor 74 is coupled to the passage 60 and
determines
the fluid pressure within the passage 60 corresponding to the depth 64 of the
fluid 32
within the well bore 16. At step 208, the controller 76 determines whether a
pressure
variation has occurred within the passage 60, thereby indicating a fluctuation
in the level
10 of the fluid 32 within the well bore 16. The controller 76 may include
processing
instructions andlor programming such that the pressure variations within the
passage 60
must exceed a predetermined amount before a corresponding fluid 32 level
fluctuation
warrants a change in the operating parameters of the pumping unit 12. However,
the
controller 76 may otherwise be configured to automatically adjust the
operating
15 parameters of the pumping unit 12 based on the pressure variations within
the passage 16.
At decisional step 210, a determination is made whether the pressure within
the
passage 60 has increased. If the pressure within the passage 60 has increased,
the method
proceeds from step 210 to step 212, where the controller 76 initiates an
increase in the
fluid 32 flow rate via the pumping unit 12. As described above, the controller
76 transmits
2 0 a control signal to the drive motor 78 to regulate the operating
parameters of the pumping
unit 12 to obtain an increase in the pumping flow rate. If a pressure increase
did not
occur, the method proceeds from step 210 to step 214.
At decisional step 214, a determination is made whether the pressure within
the
passage 60 has decreased. If the pressure within the passage 60 has decreased,
the method
2 5 proceeds from step 216 to step 218, where the controller 76 initiates a
decrease in the fluid
32 flow rate via the pumping unit 12. As described above, the controller 76
transmits a
control signal to the drive motor 78 to decrease the flow rate of the fluid 32
pumped to the
surface 14. If a pressure decrease did not occur within the passage 60, the
method
proceeds from step 216 to decisional step 220, where a determination is made
whether
3 0 additional monitoring of the pressure within the passage 60 is desired. If
additional
pressure monitoring is desired, the method returns to step 206. If no
additional monitoring
is desired, the method is complete.
CA 02441307 2003-09-16
WO 02/086322 PCT/US02/12751
16
Thus, the present invention provides an efficient fluid level controlled
pumping
system that substantially eliminates operation of a pumping unit in a "dry" or
unlubricated
condition, thereby increasing the operating life of the pumping unit. The
present invention
also provides a fluid level controlled pumping system that requires minimal
manual
operation and monitoring, thereby increasing the efficiency of pumping
operations.
Although the present invention has been described in detail, various changes
and
modifications may be suggested to one skilled in the art. It is intended that
the present
invention encompass such changes and modifications as falling within the scope
of the
appended claims.
