U.S. patent application number 14/067895 was filed with the patent office on 2015-04-30 for remote sensing of in-ground fluid level apparatus.
This patent application is currently assigned to ENDOW ENERGY, LLC. The applicant listed for this patent is ENDOW ENERGY, LLC. Invention is credited to William A. Rowe, Timothy Strunk.
Application Number | 20150118068 14/067895 |
Document ID | / |
Family ID | 52995689 |
Filed Date | 2015-04-30 |
United States Patent
Application |
20150118068 |
Kind Code |
A1 |
Strunk; Timothy ; et
al. |
April 30, 2015 |
REMOTE SENSING OF IN-GROUND FLUID LEVEL APPARATUS
Abstract
A fluid pump apparatus includes a pump chamber in a wellbore, a
drive line capable of transferring a gas pressure to the pump
chamber, a control system, an exhaust line, and a pressure sensor.
The pressure sensor is capable of remotely sensing gas pressure in
the exhaust line and providing communication to the control system.
The control system is capable of determining when the fluid level
in the pump chamber is full or near full based on input from the
pressure sensor.
Inventors: |
Strunk; Timothy;
(Georgetown, KY) ; Rowe; William A.; (Lexington,
KY) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
ENDOW ENERGY, LLC |
Georgetown |
KY |
US |
|
|
Assignee: |
ENDOW ENERGY, LLC
Georgetown
KY
|
Family ID: |
52995689 |
Appl. No.: |
14/067895 |
Filed: |
October 30, 2013 |
Current U.S.
Class: |
417/63 |
Current CPC
Class: |
F04B 49/06 20130101;
F04B 47/02 20130101 |
Class at
Publication: |
417/63 |
International
Class: |
F04B 51/00 20060101
F04B051/00 |
Claims
1. A fluid pump apparatus comprising: a. a pump chamber located in
a wellbore and having a fluid inlet, a fluid outlet port, and at
least one gas port, and b. an exhaust line providing fluidic
communication from said gas port to an exhaust chamber located a
distance above said pump chamber, and c. a control system capable
of receiving an electrical input, processing said electrical input,
and producing an electrical output signal, and d. a pressure sensor
in fluidic communication with the exhaust line and in electrical
communication with the control system, and e. said control system
is capable of receiving an electrical input from said pressure
sensor, processing said electrical input, and producing an
electrical output signal capable of indicating a near full
condition in said pump chamber.
2. The fluid pump apparatus of claim 1, further comprising: a. a
vacuum device, capable of providing negative pressure gas, in
fluidic communication with said exhaust line, and b. a valve
capable of fluidically isolating said exhaust line from said
exhaust chamber.
3. The fluid pump apparatus of claim 2, further comprising: a. a
compressed gas supply capable of providing positive pressure gas,
and b. a drive line in fluidic communication from said compressed
gas supply to said gas port, and c. a valve capable of fluidically
isolating said pressure sensor from said pump chamber, and d. a
valve capable of fluidically isolating said compressed gas supply
from said pump chamber.
4. The fluid pump apparatus of claim 1, further comprising: a. a
compressed gas supply capable of providing positive pressure gas,
and b. a drive line in fluidic communication from said compressed
gas supply to said gas port, and c. a venturi in fluidic
communication with said compressed gas supply and with said exhaust
line, and d. a valve capable of fluidically isolating said venturi
from said compressed gas supply, and e. a valve capable of
fluidically isolating said pressure sensor from said pump chamber,
and f. a valve capable of fluidically isolating said compressed gas
supply from said pump chamber.
5. The fluid pump apparatus of claim 3, further comprising: a. a
normally open check valve including a float, wherein said float is
capable of allowing the bi-directional flow of gas and downward
flow of liquid, but preventing the upward flow liquid.
6. The fluid pump apparatus of claim 4, further comprising: a. a
normally open check valve including a float, wherein said float is
capable of allowing the bi-directional flow of gas and downward
flow of liquid, but preventing the upward flow of liquid.
7. The fluid pump apparatus of claim 1, further comprising: a. said
pressure sensor positioned at least 30.5 m (100 ft.) above said
pump chamber.
8. The fluid pump apparatus of claim 3, wherein: a. said output
signal is capable of communicating with an intermediate device
being at least one member of the group consisting of a number, a
light, a level, a sound, a haptic response, and a different output
signal.
9. The fluid pump apparatus of claim 3, wherein; a. said output
signal is capable of controlling a valve to enable fluidic
communication from said gas supply to said pump chamber.
10. The fluid pump apparatus of claim 3, wherein; a. said output
signal is capable of controlling a valve to fluidically isolate
said exhaust line from said pump chamber.
11. The fluid pump apparatus of claim 3, wherein; a. said exhaust
chamber being at least one of a tank and atmosphere.
12. A fluid pump apparatus comprising: a. a pump chamber located in
a wellbore and having a fluid inlet, a fluid outlet port, and a gas
port, and b. an exhaust line providing fluidic communication from
said gas port to an exhaust chamber located a distance above said
pump chamber, and c. a control system capable of receiving an
electrical input, processing said electrical input, and producing
an electrical output signal, and d. a pressure sensor in fluidic
communication with the exhaust line and in electrical communication
with the control system, and e. said pressure sensor capable of
providing one or more electrical signals to said controller
corresponding to a near full condition in said pump chamber.
13. The fluid pump apparatus of claim 12, further comprising: a. a
vacuum device, capable of providing negative pressure gas, in
fluidic communication with said exhaust line, and b. a valve
capable of fluidically isolating said exhaust line from said
exhaust chamber.
14. The fluid pump apparatus of claim 13, further comprising: a. a
compressed gas supply capable of providing positive pressure gas,
and b. a drive line in fluidic communication from said compressed
gas supply to said gas port, and c. a valve capable of fluidically
isolating said pressure sensor from said pump chamber, and d. a
valve capable of fluidically isolating said compressed gas supply
from said pump chamber.
15. The fluid pump apparatus of claim 14, further comprising: a. a
normally open check valve including a float, wherein said float is
capable of allowing the bi-directional flow of gas and the downward
flow of liquid, but preventing the upward flow of liquid.
16. The fluid pump apparatus of claim 15, further comprising: a. a
normally open check valve including a float, wherein said float is
capable of allowing the bi-directional flow of gas and the downward
flow of liquid, but preventing the upward flow of liquid.
17. The fluid pump apparatus of claim 15, wherein: a. said output
signal is capable of communicating with an intermediate device
being at least one member of the group consisting of a number, a
light, a level, a sound, a haptic response, and a different output
signal.
18. The fluid pump apparatus of claim 14, wherein: a. said exhaust
chamber being at least one of a tank and atmosphere.
19. The fluid pump apparatus of claim 12, further comprising: a. a
compressed gas supply capable of providing positive pressure gas,
and b. a drive line in fluidic communication from said compressed
gas supply to said gas port, and c. a venturi in fluidic
communication with said compressed gas supply and with said exhaust
line, and d. a valve capable of fluidically isolating said venturi
from said compressed gas supply, and e. a valve capable of
fluidically isolating said pressure sensor from said pump chamber,
and f. a valve capable of fluidically isolating said compressed gas
supply from said pump chamber.
20. The fluid pump apparatus of claim 12, further comprising: a.
said pressure sensor positioned at least 30.5 m (100 ft.) above
said pump chamber.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] Not applicable
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
[0002] Not applicable
NAMES OF THE PARTIES TO A JOINT RESEARCH AGREEMENT
[0003] Not applicable
REFERENCE TO SEQUENCE LISTING
[0004] Not applicable
BACKGROUND
[0005] 1. Field of the Invention
[0006] The invention generally relates to an in-ground fluid
pumping system. More particularly, the invention is related to an
apparatus for remotely sensing the fluid level in a pump
chamber.
[0007] 2. Description of the Related Art
[0008] In-ground fluid pumping systems are employed to extract
petroleum oil, water, or other liquids from within the earth. These
pumping systems are often placed in a drilled well to efficiently
extract fluids from tens to hundreds of meters below the surface of
the earth (ground level). In many cases, a blend of fluids, such as
oil and water, are extracted, in addition to natural gas and
contaminates such as sand. As such, in-ground wells require robust
pumping systems to reduce the potential of various hazards while
also avoiding premature wear due to the transfer of abrasives in
the fluid.
[0009] Traditional wells date back to the 1920's, which employ a
pumpjack fluid extraction system. A pumpjack uses a walking beam,
fixed above ground, which continuously actuates a piston connected
by a series of connecting rods (sucker rods). These are
mechanically intensive pump systems, having moving components
spanning deep into the well which require maintenance due to wear,
scaling, and corrosion. Their mechanical nature causes difficulties
in remotely sensing fluid levels deep in the well.
[0010] More recently, a gas displacement pump has been introduced
as an alternative to a traditional pumpjack well pump for some
applications. Gas displacement pump systems collect a volume of
fluid in a pump chamber near the bottom of the well, which is then
pumped to a receiving tank using gas pressure. Gas displacement
wells have fewer moving parts, compared to pumpjack systems. As
such, gas displacement wells are generally less expensive than
pumpjack systems to install and operate.
[0011] These gas displacement pumps are more conducive to having
electrically connected fluid level sensing components in the well.
The lack of reciprocating components improve the capability of
electrically connected sensing systems. One electrical sensing
system relies on limit switches in the pump chamber to sense near
full and near empty fluid levels. These switches are positioned
essentially at the bottom of the well, requiring electrical cables
connected from above ground to hundreds of meters deep. Normally
two switches are positioned in the pump chamber to sense high and
low fluid levels. The high fluid level corresponds to a near full
condition and the low fluid level corresponds to a near empty
condition. When high fluid level is detected, the pump chamber is
ready to be pressurized with gas to drive the fluid towards the
surface. When a near empty fluid level is detected, pumping towards
the surface is complete and the pump chamber gas is exhausted to
allow the chamber to refill with fluid from the wellbore. Since
conventional high and low sensors are located in the pump chamber,
they are directly exposed to oil, water, gas and abrasives. These
switches and electrical connections pose serious reliability and
safety concerns.
[0012] It is preferred that electrical components are not exposed
to oil or gas. It is also preferred that electrical cables, if any,
do not extend essentially the full depth of the well. It is further
preferred that a fluid evacuation rate, such as barrels of oil per
day (bpd), be maximized.
SUMMARY
[0013] The present invention provides a fluid pump apparatus for
use in a gas displacement pump system capable of sensing when the
fluid level in a pump chamber is full or near full without a sensor
located in the pump chamber. The present invention teaches a novel
apparatus for detecting pump chamber full or near full with a
pressure sensor located in a gas line. The pressure sensor can be a
great distance from the pump and therefore can be located on the
surface where the conditions are not harsh and maintenance is
facilitated.
[0014] A first embodiment of the present invention provides a fluid
pump apparatus for use in a gas displacement pump capable of
sensing a fluid level in a pump chamber using a full complement of
valves, a down-hole exhaust valve, and a vacuum pump.
[0015] A second embodiment of the present invention provides a
fluid pump apparatus for use in a gas displacement pump capable of
sensing a fluid level in a pump chamber using a minimum set of
valves, all on or above the earth surface, and a venturi.
[0016] Both the first and second embodiments are capable of sensing
near-full fluid level in the pump chamber when the pump chamber gas
pressure is either above or below atmospheric pressure, and having
a sensing means tens to hundreds of meters from the fluid
level.
[0017] Features and advantages of the present invention will be
more understood through the detailed description and in reference
to the figures which follow.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] FIG. 1a is an elevation view, not to scale, schematically
representing a first embodiment of a fluid pump apparatus;
[0019] FIG. 1b is taken from View A-A of FIG. 1a showing a top
view, not to scale, of schematically represented features;
[0020] FIG. 2a shows FIG. 1a in a negative pressure fill state;
[0021] FIG. 2b shows FIG. 1a in a near-full sense state following
negative pressure fill;
[0022] FIG. 3a shows FIG. 1a in a positive pressure fill state;
[0023] FIG. 3b shows FIG. 1a in a near-full sense state following
positive pressure fill;
[0024] FIG. 4a is an elevation view, not to scale, schematically
representing a second embodiment of a fluid pump apparatus;
[0025] FIG. 4b is taken from View B-B of FIG. 4a showing a top
view, not to scale, of schematically represented features;
[0026] FIG. 5 shows FIG. 4a in a negative pressure fill and sense
state;
[0027] FIG. 6 shows FIG. 4a in a positive pressure fill and sense
state;
DETAILED DESCRIPTION
[0028] It is to be understood that various omissions and
substitutions of equivalents are contemplated as circumstances may
suggest or render expedient, but these are intended to cover the
application or implementation without departing from the spirit or
scope of the claims of the present invention. It is to be
understood that the phraseology and terminology used herein is for
the purpose of description and should not be regarded as limiting.
The use of "including," "comprising," or "having" and variations
thereof herein is meant to encompass the items listed thereafter
and equivalents thereof as well as additional items. Further, the
terms "a" and "an" herein do not denote a limitation of quantity,
but rather denote the presence of at least one of the referenced
item. It is also to be understood that the use of the term "fluid"
denotes a liquid, but "fluidic", "fluidic communication",
"fluidically coupled" or like terms can denote a liquid or a gas as
is commonly used in the industry.
[0029] An overall description of the pumping system will be
described, corresponding to FIGS. 1a-b. Turning to FIG. 1a, fluid
pump apparatus 11a comprises a fluidic system 21 (normally
described as a "well") formed of a wellbore 10 positioned in an
earth formation 15 containing fluid such as oil or water, but may
also include natural gas and contaminants such as sand, at a
generally static fluid level 20. The wellbore 10 is generally a
tubular steel casing extending from an upper end near an earth
surface 25, terminating at a lower end tens to hundreds of meters
into the earth formation 15. The wellbore 10 may include
perforations 30 near the lower end on the sides and bottom surface,
which permits fluid to enter.
[0030] A wellbore casing is normally used for deep wells to
preserve their shape, but in some instances, the integrity of the
surrounding earth is adequately sound without a casing. For
example, a well (such as fluidic system 21) drilled into solid rock
or tight clay may not require a separate casing. The present
invention will function adequately in these instances, therefore is
within the scope of what is described herein as a fluid pump
apparatus (11a or 11b).
[0031] Returning again to FIGS. 1a-b, pump chamber 35 is positioned
near the bottom of the wellbore 10 proximate the perforations 30.
The pump chamber 35 includes a pump chamber bottom 36, a chamber
top 37, and generally circular sides. The pump chamber bottom 36
includes a normally round hole, providing a fluid inlet 40. The
pump chamber bottom 36 may be flat, conical, convex, concave, or
other such shape. A conically shaped pump chamber bottom 36 is
shown throughout the figures. The chamber top 37, more clearly
shown in FIG. 1b, includes a fluid outlet port 45 and a gas port
50. The chamber top 37 is preferably a separate component
mechanically coupled and fluidically sealed to the pump chamber
35.
[0032] Within the pump chamber 35 is a fluid inlet check ball 55
held in position by retainers (not shown) which is common for check
ball designs. The retainers allow movement of the fluid inlet check
ball 55 but contain it to a position capable of sealing against a
fluid inlet ball seat 56 when a force balance on the fluid inlet
check ball 55 favors the sealing position. Also within the pump
chamber 35 is a fluid outlet port 45 mechanically coupled to the
chamber top 37. The fluid outlet pipe 48 is a hollow pipe of
substantially smaller diameter than the pump chamber, which
provides a fluidic path from an intake port 46 of the pump chamber
35 to a fluid outlet exit port 47 positioned to dispense the pumped
fluid to a receiving tank 60. The fluid outlet pipe 48 may
optionally be formed integrally to the pump chamber 35. The fluid
outlet pipe 48 includes a fluid outlet check ball 38, which forms a
seal against fluid outlet ball seat 42 to prevent fluid in the
fluid outlet pipe 48 from flowing back to the pump chamber 35.
[0033] The receiving tank 60 is positioned near the earth surface
25, normally referred to as "ground level". It may be buried below
the earth surface 25, may be positioned above the earth surface 25,
or may be on a mobile transport such as a truck (not shown) or
trailer (not shown). The receiving tank 60 may be an open trough
design, as shown in the figures, or may be a closed or partially
closed shape.
[0034] Also shown in FIG. 1a is a pneumatic system 31. A compressed
gas supply 65 is fluidically coupled to a drive line 70. A
compressed gas supply 65 may be a gas compressor, wherein gas is
compressed on demand, or may be bottled gas. The gas may be air,
natural gas, or an inert gas such as nitrogen or argon. The drive
line 70 terminates at gas port 50 shown in View A-A (FIG. 1b) which
is a part of chamber top 37. In-line with the drive line 70 is
valve 75, which controls the flow of gas through the drive line 70
and into the pump chamber 35, also isolating the compressed gas
supply 65 from the pump chamber 35. An exhaust line 110 branches
off the drive line 70 providing a vent to an exhaust chamber (not
shown) with low resistance to gas flow, normally above the earth
surface 25. The exhaust chamber may be a tank capable of receiving
gas, or it be may be the atmosphere. A tank may be used to capture
and possibly recycle gas, particularly if an inert gas such as
nitrogen or argon is used. A tank may be configured to perform in
similar fashion to the atmosphere, having a large volume capacity
and having means for providing gas to pneumatic system 31 on
demand.
[0035] In parallel with exhaust line 110 is pressure sensor 105,
capable of measuring positive and negative pressure in this line.
Also in parallel with exhaust line 110 is vacuum line 80, which is
coupled to a vacuum device such as vacuum pump 85, capable of
providing a vacuum means to exhaust line 110 and pump chamber 35.
In-line with exhaust line 110 is valve 115, which controls the flow
of gas through the exhaust line 110 and fluidically isolates the
exhaust line 110 from an exhaust chamber. Also in-line with the
exhaust line 110 is valve 90 which controls the flow of gas through
the exhaust line 110 and isolates the pump chamber 35 from the
pressure sensor 105.
[0036] Valves 75 and 90 are shown in a "down-hole" configuration,
wherein these valves are positioned in the wellbore 10 which may
exceed 610 m (2000 ft.) below the earth surface 25. In an alternate
configuration, these valves may be integrated with additional
features such as chamber top 37. It should be noted, however, that
the wellbore 10 may have an internal diameter as small as 10 cm (4
in.). Therefore, the usable outside diameter of down-hole devices
is about 7.7 cm (3 in.), which is the primary limitation to
locating control components below the earth surface 25.
[0037] Valve 115 may be electronically or pneumatically controlled
as further described in a subsequent paragraph. Alternately, valve
115 may be replaced by a check valve (such as normally closed check
valve 116 shown in FIG. 4a) which is capable of operation passively
with no external controls. For some embodiments, or some operating
conditions, a passive exhaust valve may provide a "failsafe",
capable of preventing an unsafe pressure buildup in the event of an
electrical or control system 120 malfunction. A passive exhaust may
also be preferred for embodiments in which providing an
electrically or pneumatically controlled valve is impractical.
[0038] A portion of pneumatic system 31 may be designed to provide
service to multiple wells (such as fluidic systems 21) in a "hub
and spoke" configuration. A pneumatic hub 34 may consist of at
least the compressed gas supply 65, and may optionally include a
vacuum device such as vacuum pump 85. The pneumatic hub 34 may be
configured in a first location, providing service to a well or to
multiple wells in a second, third, or any number of well locations
("spokes") within the practical limits of cost, distance, fluidic
friction, and the like. Such a configuration may be practical due
to cost and maintenance efficiencies, or in cases in which access
to a well may be limited by, for example, the earth surface 25
terrain, environmental sensitivities, or personal privacy.
[0039] FIG. 1a also shows a control system 120 having
representative control lines communicating with "control
components". Broken control lines are shown for clarity. "Control
components" generally include electrically controlled devices in
the pneumatic system 31. In the figure, this includes valve 75,
valve 90, valve 115, valve 100, pressure sensor 105, compressed gas
supply 65, and vacuum pump 85. (Each of the valves are referred to
generally as "active valve components".) The control system 120 may
include multiple sub-systems to provide, for example, supervisory
control, data acquisition, and programmable logic. This system is
generally capable of receiving electrical signals, processing the
signals, then producing an output signal capable of controlling or
reporting. In one aspect of this invention, the output signal is
capable of indicating a near full condition in the pump chamber.
More particularly, pressure sensor 105 remotely measures a pressure
in exhaust line 110, then provides a corresponding electronic
signal to the control system 120. The control system 120 relies on
programmable logic to interpret the electrical signal, and to
determine if an action should be performed. For example, if the
control system 120 interprets a pressure, or change in pressure,
corresponding to thresholds defined in the programmable logic, a
change in the state of valves or pumps may occur. In one instance,
once a near full condition is determined by the control system 120,
a change to a fluid pumping state may occur by opening valve 75 to
allow fluidic communication of the compressed gas supply 65 to the
pump chamber 35, or by closing valve 90 to isolate pump chamber 35
from exhaust line 110.
[0040] The pressure sensor 105 is robust in operation. It is
capable of sensing a pressure in an exhaust line having a number of
bends, angles, or restrictions with no degradation in the quality
of the sensed pressure.
[0041] In application, "near full" may indicate a variable level
depending on the behavior of the pressure sensor 105, the impedance
of pneumatic system 31 and the logic sensitivity programmed into
the control system 120. For most applications, is not necessary to
optimize the design to a precise level prior to initiating the pump
cycle. Near full may indicate 100% full for one well, 90% full for
another, and 80% full for yet another. An individual well may also
change with time, resulting in "near full" changing from 90% to 85%
or 95% while still within the spirit and scope of a "near full"
condition. Even in a hub and spoke configuration, wherein a
pneumatic hub 34 is shared among multiple wells, a range of "near
full" thresholds may occur from well to well.
[0042] Returning again to a discussion of output signals, an output
signal may alternately communicate with one or more intermediate
devices wherein additional logic or actions may determine if, or
when, a change in the state of valves or pumps will occur. For
example, an intermediate device may include an electrical device
(not shown) for providing, for example, a number, a light, a level,
a sound, a haptic response, a different output signal, or any
combination thereof to a user or to a secondary control system,
which may be an electrical or a pneumatic control system.
[0043] In addition to controlling the systems described herein,
control system 120 may also include monitoring of local
environmental conditions such as weather, security, and safety, and
may provide a means for external data monitoring and reporting, via
wired or wireless communication. Depending on the control
configuration, more than one control line may be used. Electrical
lines may pass through the control system 120, or may communicate
directly with any of the control components. The actual wiring of
each control component is considered designer's choice, and is
known by those skilled in the art.
[0044] Now describing the active valve components in more detail,
each of the valves may be electronically controlled. Exemplary
electronically controlled valves may include solenoid valves, ball
valves, proportional control valves, stepper controlled valves, and
the like. Alternately, pneumatically controlled valves may also be
used. In these cases, an additional gas line may be required to
actuate the valve. Control of the additional gas line may further
require an electronically controlled valve, but such pneumatically
controlled valves may have advantages in more severe operating
environments or in cases in which safety regulations prohibit the
use of electrical communication.
[0045] Continuing to reference FIG. 1a, a check valve 95 may
optionally be included in-line with drive line 70, which will
isolate fluid from the pneumatic system 31 and providing a more
definite output signal from pressure sensor 105 to control system
120 when a pressure change is measured. The moving component of the
check valve 95, float 96, is designed to be buoyant in the fluid by
having a specific gravity less than or equal to the specific
gravity of the fluid. The float 96 may be a sphere, such as shown
in the figures, but may have various shapes. Check valve 95
protects pneumatic system 31, by allowing air or other gas to flow
into or out of pump chamber 35 with minimal fluidic resistance. The
orientation of the check valve 95 is such that gravity causes the
float 96 to fall away, providing a "normally open" valve, allowing
the flow of gas. The float 96 closes when a fluid level (not shown
in FIG. 1a) rises, causing the check valve 95 to seal, preventing
the upward flow of fluid above the check valve 95. Upon sealing,
the pressure sensor 105 will sense a sudden change in pressure,
providing a positive indication that the pump chamber 35 is near
full.
[0046] In many applications, the pressure sensor 105 will remotely
sense a fluid level a distance of at least 30.5 m (100 ft.) above
pump chamber 35. In other applications, the pressure sensor 105
will be a distance of at least 305 m (1000 ft.) above pump chamber
35. Thus, the pressure sensor 105 in combination with the control
system 120 is capable of remotely sensing a fluidic level in the
pump chamber by reading the gas pressure in the exhaust line
110.
[0047] Fluid levels in fluidic system 21 will now be introduced
into FIGS. 2a-b and 3a-b. In addition, the states of the active
valve components will be shown in more detail.
[0048] In FIG. 2a, a negative pressure fill state is described,
corresponding to FIG. 1a. A wellbore fluid level 32 is shown below
chamber top 37. For pump chamber fluid level 33 to fill (or nearly
fill) the pump chamber 35, a vacuum is created according to the
following description: Vacuum pump 85 is engaged, valve 100 and
valve 90 are open to allow flow, and check valve 95 is in a
normally open state, causing a vacuum in pump chamber 35, as shown
by vacuum arrows 44. (For a well using a pneumatic hub 34, vacuum
pump 85 may already be actuated.) Valves 75 and 115 are closed,
preventing flow. Fluid is pulled from wellbore 10 by flowing
through fluid inlet 40, past fluid inlet check ball 55, and into
pump chamber 35 causing the pump chamber fluid level 33 to
rise.
[0049] Turning now to FIG. 2b, a near-full sense state after
negative pressure fill is described, corresponding to FIG. 1a.
Control system 120 will be conditioned to determine an appropriate
time duration to predict the pump chamber fluid level 33 to nearly
fill pump chamber 35. Once near full is predicted, valve 100 will
close (preventing flow), then pressure sensor 105 will provide more
than one signal to control system 120, spaced apart by a time delay
determined by the control system 120. Control system 120 will
calculate any difference in signals. A small difference indicates
the pump chamber fluid level 33 is stable and is not rising. When
the fluid level 33 is stable, then the negative pressure reported
by pressure sensor 105 is compared to a threshold and if below the
threshold, then the fluid chamber is near full. If the stable
pressure is not below the threshold, the pump chamber has not
achieved a near full condition. The near full stable pressure
threshold is a negative number. The time delay is dependent on the
responsiveness of the pneumatic system 31 which is, in part,
determined by the depth of the fluidic system 21, the rate of
change of pump chamber fluid level 33, and the pneumatic impedance
of the pneumatic system 31. If control system 120 determines that
"near full" has not been achieved, a return to the negative
pressure fill state may be required.
[0050] The control system 120 is designed to detect "near full",
then evacuate the pump chamber 35 with minimal delay, providing a
maximized fluid evacuation rate. In addition, the negative pressure
fill described herein further improves the fluid evacuation rate,
thereby maximizing fluid production even in low production
wells.
[0051] FIG. 3a shows FIG. 1a in a positive pressure fill state,
wherein the wellbore fluid level 32 is above the pump chamber 35,
thereby allowing the positive head pressure to provide the force
for filling the pump chamber 35. Thus, valves are controlled simply
to provide a vent to an exhaust chamber. In this embodiment, valve
100 is closed, isolating exhaust line 110 from vacuum pump 85. In
the case of a pneumatic hub 34, vacuum pump 85 may continue to be
engaged to supply vacuum pressure to other wells. For a vacuum pump
85 dedicated to a well, it would likely be disengaged. Valves 115
and 90 are open, providing a vent from pump chamber 35 to an
exhaust chamber, enabling pump chamber fluid level 33 to rise with
minimal fluid resistance.
[0052] FIG. 3b describes a near-full sense state following the
positive pressure fill state. Control system 120 will be
conditioned to determine an appropriate time duration to predict
when the pump chamber fluid level 33 should be nearly full in the
pump chamber 35. Once near full is predicted, valve 115 changes
state from opened to closed, isolating exhaust line 110 from the an
exhaust chamber. Pressure sensor 105 will then provide more than
one signal to control system 120, spaced apart by a time delay. As
previously described, control system 120 will determine if the pump
chamber 35 is near full, or if a return to the previous fill state
is needed. In the positive pressure fill case, the pressure
threshold indicating near-full is a positive number. When sensor
105 detects a pressure in the sense state that is below the
threshold, then near-full is detected. The control system 120 is
optimized to sense a near full condition, then immediately evacuate
the pump chamber 35, improving the fluid evacuation rate.
[0053] FIGS. 4a-b provide a fluid pump apparatus 11b, corresponding
to the second embodiment. Fluid levels in the fluidic system 21 are
not shown for clarity. In FIG. 4a, the fluidic system 21 is similar
to FIG. 1a, with exceptions noted.
[0054] Pneumatic system 41 will be discussed relative to pneumatic
system 31 shown in FIG. 1a. The compressed gas supply 65, which may
be a gas compressor or bottled gas as previously described, is
fluidically coupled to the drive line 70 and to a vacuum device. In
this configuration, the vacuum device shown is a venturi 86. The
drive line 70 terminates at gas port 50 shown in View B-B (FIG. 4b)
which is a part of chamber top 39. In-line with the drive line 70
is valve 75, which controls the flow of gas through the drive line
70 and into the pump chamber 35. It should be noted that valve 75
is shown above ground (above earth surface 25), in contrast to the
down-hole position shown in FIG. 1a. Valve 75 may be in either
position or any position in between. This is designer's choice
based on practical implementation constraints dependent on the
specific well configuration. In parallel with exhaust line 110 is
vacuum line 80, which is coupled to the venturi 86. Venturi 86 is
capable of creating a vacuum from a positive pressure source such
as compressed gas supply 65. Venturi 86 is independently controlled
by valve 125, which provides pressure on-demand to the venturi 86,
resulting in a vacuum created by the well-known venturi effect. In
operation, venturi 86 provides a vacuum to vacuum line 80, causing
a vacuum in exhaust line 110 and pump chamber 35, which is capable
of being sensed by pressure sensor 105. In FIG. 4a, pneumatic hub
34 includes compressed gas supply 65, valve 125, and venturi
86.
[0055] The exhaust line 110 is shown directly coupled to the
chamber top 39, in contrast with branching off of drive line 70, as
previously shown in FIG. 1a-b. Check valve 95 is not shown in the
figure.
[0056] FIG. 4b shows a top view of chamber top 39 taken from FIG.
4a, view B-B. Chamber top 39 includes fluid outlet port 45 and gas
port 50, but also includes a second port, gas port 51.
[0057] Returning again to FIG. 4a, exhaust line 110 is shown
in-line with check valve 116. This valve is normally closed, which
passively inhibits the flow of gas in, but enables the flow of gas
out of, exhaust line 110. As is common with check valves, there is
a "cracking pressure" below which, the check valve will remain
closed. A preferred cracking pressure is about 70 cm water column
(1 psi).
[0058] Pressure sensor 105 is shown positioned in parallel with
vacuum line 80, which is in parallel with exhaust line 110. It
should be noted that the pressure (positive or negative) in exhaust
line 110 will be essentially equivalent at least between valve 90,
venturi 86, and check valve 116, therefore the pressure sensor 105
may be functionally positioned between these components. Practical
considerations will likely determine the location of this sensor,
although it is preferred that the pressure sensor 105 will be
positioned above the pump chamber 35. It is most preferred that
pressure sensor 105 be located above the earth surface 25, which
will likely will be tens to hundreds of meters above pump chamber
35.
[0059] Fluids in fluidic system 21 will now be introduced into
FIGS. 5 and 6, including the states of the active valve
components.
[0060] FIG. 5 shows a negative pressure fill state and simultaneous
sense state for fluid pump apparatus 11b shown in FIG. 4a. In this
instance, the wellbore fluid level 32 is shown below chamber top
39. For pump chamber fluid level 33 to fill (or nearly fill) the
pump chamber 35, a vacuum is created by supplying a pressure from
compressed gas supply 65, through valve 125 (which is in an open
state to allow gas flow), through venturi 86, then exhausted to the
an exhaust chamber. This airflow pulls air from vacuum line 80
according to the venturi effect. Check valve 116, which is normally
closed, remains closed due to the vacuum force acting upon it.
Valve 90 is open to allow vacuum to the pump chamber 35, causing a
vacuum to act on the pump chamber fluid level 33 as shown by vacuum
arrows 44. Given the minimal valves in this configuration, there is
no means for providing a closed volume from which to sense
pressure. However, the apparatus provides a means of pressure
sensing while gas is exhausted to an exhaust chamber. In this
instance, pressure sensor 105 may sense continuously or during time
intervals as determined by control system 120. As pump chamber
fluid level 33 rises, the volume of gas in the pump chamber 35
decreases, allowing for higher levels of vacuum (negative pressure)
in exhaust line 110. When the vacuum level reported by pressure
sensor 105 is above a threshold (vacuum higher than the threshold
is detected), then the fluid chamber is near full.
[0061] FIG. 6 shows a positive pressure fill state for fluid pump
apparatus 11b shown in FIG. 4a in which the wellbore fluid level 32
is above the pump chamber 35. Thus, valves are controlled simply to
provide a vent to an exhaust chamber to allow wellbore fluid to
enter the pump chamber. In this embodiment, valve 125 is closed,
isolating exhaust line 110 from compressed gas supply 65. In the
case of a pneumatic hub 34, compressed gas supply 65 may continue
to be engaged to supply gas pressure to other wells. For a
dedicated well, it would likely be disengaged. Valve 90 is open,
providing a vent from pump chamber 35 to an exhaust chamber,
enabling pump chamber fluid level 33 to rise with minimal fluidic
resistance. As previously described, the minimal valves in this
configuration do not provide a closed volume from which to sense
pressure. However, the apparatus provides a means of pressure
sensing while gas is displaced from the pump chamber 35, exhausting
to the atmosphere. In this instance, pressure sensor 105 may sense
continuously or during time intervals as determined by control
system 120. As the pump chamber fluid level 33 rises, the volume of
gas (such as air) in the pump chamber 35 is vented through the
venturi 86 to an exhaust chamber (the venturi will allow air
passage even when not energized). The venturi 86 causes a flow
restriction, resulting in a backpressure in the fluidic system.
This is sensed by the pressure sensor 105 as a low level positive
pressure. A sensor having an increased sensitivity is preferred for
this configuration. The pressure reported by pressure sensor 105 is
compared to a threshold and if below the threshold, then the fluid
chamber is near full.
[0062] It will be appreciated by those skilled in the art that
valves may be capable of control via a pneumatic controller.
[0063] Systems may be configured differently than the figures show
while falling within the scope of the present invention. For
example, redundant valves may be used in any fluidic line. In
another example, vacuum line 80 may have essentially zero length.
In yet another example, vacuum devices such as vacuum pump 85 and
venturi 86 may be interchanged.
[0064] It is contemplated, and will be clear to those skilled in
the art that modifications and/or changes may be made to the
embodiments of the invention. Accordingly, the foregoing
description and the accompanying drawings are intended to be
illustrative of the example embodiments only and not limiting
thereto, in which the true spirit and scope of the present
invention is determined by reference to the appended claims.
* * * * *