U.S. patent application number 14/250516 was filed with the patent office on 2014-08-07 for cranked rod pump method.
This patent application is currently assigned to Unico, Inc.. The applicant listed for this patent is Unico, Inc.. Invention is credited to Thomas L. Beck, Michael D. Dry, Benjamin J. Gregory, Michael A. MacDonald, Ronald G. Peterson.
Application Number | 20140219827 14/250516 |
Document ID | / |
Family ID | 48669682 |
Filed Date | 2014-08-07 |
United States Patent
Application |
20140219827 |
Kind Code |
A1 |
Gregory; Benjamin J. ; et
al. |
August 7, 2014 |
Cranked Rod Pump Method
Abstract
An improved apparatus and method are disclosed, for pumping
fluids, such as water and/or hydrocarbons, from a subterranean
formation or reservoir, through use of a cranked rod pumping (CRP)
apparatus for imparting reciprocating substantially vertical motion
to a rod of a sucker-rod pump having a pump stroke. The CRP
apparatus includes a motor driven cranked mechanical actuator
arrangement. The cranked mechanical actuator arrangement includes a
substantially vertically moveable member attached to the rod of the
sucker-rod pump for imparting and controlling vertical motion of
the rod of the sucker-rod pump. The actuator arrangement may
include pneumatic counterbalancing.
Inventors: |
Gregory; Benjamin J.;
(Racine, WI) ; Beck; Thomas L.; (Union Grove,
WI) ; Peterson; Ronald G.; (Racine, WI) ;
MacDonald; Michael A.; (Racine, WI) ; Dry; Michael
D.; (Racine, WI) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Unico, Inc. |
Franksville |
WI |
US |
|
|
Assignee: |
Unico, Inc.
Franksville
WI
|
Family ID: |
48669682 |
Appl. No.: |
14/250516 |
Filed: |
April 11, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
13155585 |
Jun 8, 2011 |
8708671 |
|
|
14250516 |
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|
12251789 |
Oct 15, 2008 |
8328536 |
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13155585 |
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Current U.S.
Class: |
417/53 ;
29/401.1 |
Current CPC
Class: |
F04B 17/006 20130101;
F24T 10/10 20180501; Y02P 80/10 20151101; E21B 43/127 20130101;
F04B 47/026 20130101; Y02E 10/10 20130101; Y10T 29/49716 20150115;
F04B 47/022 20130101; F24T 10/30 20180501; Y02E 10/46 20130101;
F04B 47/02 20130101; F03G 6/00 20130101; F24T 2010/56 20180501;
E21B 43/126 20130101 |
Class at
Publication: |
417/53 ;
29/401.1 |
International
Class: |
E21B 43/12 20060101
E21B043/12; F04B 47/02 20060101 F04B047/02 |
Claims
1. A method for extending the operating life of a hydrocarbon well
having a walking beam apparatus operatively connected thereto for
imparting reciprocating substantially vertical motion to a rod of a
sucker-rod pump having a pump stroke disposed in the well, the
method comprising: disconnecting the rod from the walking beam
apparatus, and operatively connecting the rod to a CRP
apparatus.
2. The method of claim 1, further comprising, operating the CRP
apparatus at a lower production rate than the production rate of
the walking beam pump prior to its replacement by the CRP
apparatus.
3. The method of claim 1, further comprising, mounting the CRP
apparatus directly on a wellhead of the well.
4. The method of claim 1, further comprising, leaving the walking
beam apparatus in place adjacent the well.
5. A method for pumping fluid from a source of fluid located in a
remote location, the method comprising: providing a CRP apparatus
with the CRP including a cranked mechanical actuator arrangement
having a vertically movable member attached to a rod of a
sucker-rod pump configured for imparting and controlling vertical
motion of the rod of the sucker-rod pump; and a motor having a
rotatable element thereof operatively connected to the vertically
movable member of the cranked mechanical actuator arrangement in a
manner establishing a fixed relationship between rotational
position of the rotatable element of the motor and vertical
movement of the vertically movable member; operatively attaching
the CRP apparatus to the source of fluid; and pumping fluid from
the source of fluid.
6. The method of claim 5, further comprising, attaching the CRP
apparatus to a stand-alone source of power.
7. The method of claim 6, the stand-alone source of power comprises
a solar energy power source.
8. The method of claim 5, further comprising, providing the source
of fluid at the remote location.
9. The method of claim 8, wherein the source of fluid at the remote
location comprises a fluid well, and the method further comprises
providing the fluid well.
10. A method for starting a CRP apparatus including a motor coupled
to a crank in a fully lowered, stationary position through a full
rotation, the method comprising: coupling the crank to a vertically
movable member attached to a rod of a sucker-rod pump for imparting
and controlling vertical motion of the rod of the sucker-rod pump;
coupling the motor to the vertically movable member establishing a
fixed relationship between rotation position of the motor and
vertical movement of the vertically movable member; rotating the
motor of the CRP apparatus in a first direction; rotating the motor
in a second direction if the motor rotational speed in the first
direction slows below a threshold speed; and rotating the motor,
sequentially, in the first and second direction motor can rotate
the crank through a full rotation cycle, thereafter continue
rotating the crank in a single rotational direction imparting
reciprocating vertical rotation to the rod of the sucker-rod pump.
Description
CROSS-REFERENCE TO RELATED PATENT APPLICATIONS
[0001] This patent application is a divisional application of
co-pending U.S. patent application Ser. No. 13/155,585, filed Jun.
8, 2011 and claims the benefit of U.S. Non-Provisional patent
application Ser. No. 12/251,789, filed Oct. 15, 2008, now U.S. Pat.
No. 8,328,536, issued Dec. 11, 2012, which claims the benefit of
U.S. Provisional Patent Application No. 60/979,986, filed Oct. 15,
2007, the entire teachings and disclosures of such documents are
incorporated herein by reference thereto.
FIELD OF THE INVENTION
[0002] This invention relates to pumping of fluids, such as water
and/or hydrocarbons, from subterranean formations or reservoirs,
and more particularly to a pumping apparatus and method for use in
such pumping applications.
BACKGROUND OF THE INVENTION
[0003] For many years, the familiar "horsehead" walking-beam type
mechanism has been used for pumping fluids such as water and/or oil
from subterranean formations. As discussed at length in commonly
assigned co-pending U.S. patent application Ser. No. 11/761,484,
titled "Linear Rod Pump Apparatus And Method," by Beck et al.,
conventional walking beam apparatuses have a number of
disadvantages, not the least of which is their large size. In
addition, performance of the walking beam pump apparatus is largely
a function of the design in connection of a number of mechanical
parts, which include massive counter-weights and complex drive
mechanisms which are difficult to control for obtaining maximum
pumping efficiency or to compensate for changes in the condition of
the well over time.
[0004] Also, for potential well sites in very remote locations, and
particularly in locations without access to a power grid and no
practical road access for regularly servicing a pumping apparatus
or a motor generator, batteries, or other traditional stand-alone
power source for a pumping apparatus, it has heretofore been
impractical, and in some cases impossible, to utilize a
conventional walking-beam apparatus or other known types of prior
pumping apparatuses and methods. As a result, potentially valuable
energy resources have remained untapped.
[0005] Although the linear rod pump apparatus and methods,
disclosed in the above-referenced '484 to Beck, provide significant
improvement over other prior pumping apparatuses and methods in
many pumping applications, the continually reversing motor utilized
in the linear rod pump apparatus and methods disclosed in Beck '484
may not be desirable in some pumping applications. For such
applications, another type of apparatus and method which could
operate without continually reversing the motor might prove to be
more desirable.
[0006] It is particularly desirable to provide such an improved
apparatus and method for pumping fluid from hydrocarbon wells, or
other fluid reservoirs, which are located so remotely from any
source of line power or access roads that the only convenient
source of energy for powering the pumping apparatus in an
unattended mode would be a solar array. It is particularly
desirable, in this regard, for some applications to have the solar
array be the sole source of power, without the need for reliance
upon any back-up batteries or other capacitive energy storage.
BRIEF SUMMARY OF THE INVENTION
[0007] The invention provides an improved apparatus and method for
pumping fluids, such as water and/or hydrocarbons, from a
subterranean formation or reservoir, through use of a cranked rod
pumping (CRP) apparatus for imparting reciprocating substantially
vertical motion to a rod of a sucker-rod pump having a pump stroke.
A CRP apparatus, according to the invention, includes a motor
driven cranked mechanical actuator arrangement. The cranked
mechanical actuator arrangement includes a substantially vertically
moveable member attached to the rod of the sucker-rod pump for
imparting and controlling vertical motion of the rod of the
sucker-rod pump.
[0008] The cranked mechanical actuator arrangement may include a
frame having a base thereof which is adapted for attachment to the
wellhead of the well. The frame further includes at least two
linear guide rails extending vertically upwardly from the base when
the base is attached to the wellhead. The vertically moveable
member is slideably mounted on the linear guides and constrained by
the guides for substantially linear reciprocating vertical movement
along the guides.
[0009] In some forms of the invention, the cranked mechanical
actuator arrangement may further include a crank element and an
articulating link element. The crank element is operatively coupled
at a first attachment point thereof to the rotatable element of the
motor for rotation in a fixed drive ratio with the rotatable
element of the motor. In some forms of the invention, the
mechanical actuator arrangement may also include a drive
arrangement operatively connect between the rotatable element of
the motor in the first attachment point of the crank element, such
that the crank element rotates at a different speed than the
rotatable element of the motor in a fixed drive ratio. The
articulating link of the cranked mechanical actuator arrangement
may have first and second attachments thereof, disposed at a spaced
relationship from one another along the articulating link element.
The first attachment point of the articulating link element may be
pivotably joined to the crank element at a second attachment point
of the cranked element, with the second attachment point of the
cranked element being spaced eccentrically, radially outward from
the first attachment point of the cranked element. The second
attachment point of the articulating link element may be pivotably
attached to the vertically moveable member.
[0010] In some forms of the invention, at least one of the cranked
element and/or the articulating link element may further include an
additional attachment point for changing the stroke of the
vertically moveable member along the guides, to thereby change the
pump stroke. The motor and/or the drive apparatus may be mounted on
the base of the frame.
[0011] In some forms of the invention, the cranked rod mechanical
actuator may further include a pneumatic counterbalance arrangement
operatively connected between the frame and the vertically moveable
member. The pneumatic counterbalance arrangement may include at
least one pneumatic cylinder that is operatively connected between
the base and the vertically moveable member, for storing energy
during a portion of the downward stroke of the vertically moveable
member and for releasing the stored energy during a portion of a
subsequent upward stroke of the vertically moveable member. In some
forms of the invention, at least one pneumatic cylinder may be
disposed between the vertically moveable member and the base, to
thereby provide a physically compact apparatus, and to more
advantageously align the pneumatic cylinder to apply force between
the vertically moveable member in the base in a direct rather than
an offset manner.
[0012] In some forms of the invention, the articulating link
element may be configured to include an offset section thereof, to
thereby enhance alignment of various moving parts of the CRP
apparatus with one another.
[0013] In some forms of a CRP apparatus, according to the
invention, the motor and/or gearbox are disposed on one side of one
or more linear guide rails extending vertically upward from the
base of the frame, and the vertically movable member being
slidingly disposed on an opposite side of the one or more linear
guide rails. The crank element and the articulating link element
have respective lengths thereof, and the vertical location of the
first attachment point of the crank element above the base of the
frame is cooperatively selected so that the vertically movable
member is constrained to always hang below the first attachment
point of the articulating link in any angular position of the crank
element, during operation of the CRP apparatus, in such a manner
that gravitational force will cause the vertically movable member
to be slidingly held in contact with the one or more linear guide
rails as the motor is controlled to impart reciprocating motion to
the vertically movable member along the one or more linear guide
rails.
[0014] The invention may also take the form of a method for
constructing, installing, operating, replacing, and/or maintaining
a CRP apparatus in accordance with the invention. In one form of
the invention, a method is provided for extending the life of a
hydrocarbon well having a walking beam apparatus operatively
connected thereto for imparting reciprocating substantially
vertical motion to a rod of a sucker-rod pump having a stroke
disposed in the well, by disconnecting the rod from the
walking-beam apparatus and operatively connecting the rod to a CRP
apparatus according to the invention.
[0015] A method for replacing a walking beam apparatus with a CRP
apparatus, according to the invention, may further include
operating the CRP apparatus at a slower stroke rate than the stroke
rate of the walking beam pump prior to its replacement by the CRP
apparatus. The method, according to the invention, may include
mounting the CRP apparatus directly on a wellhead of the well, to
thereby preclude the need for a separate mounting structure for the
CRP apparatus. A method, according to the invention, may also
include leaving the walking beam apparatus in place adjacent to the
well, after installation of the CRP apparatus.
[0016] A CRP apparatus, according to the invention, may also
include a motor drive and controller for operating the motor in a
substantially constant input power operational mode. The CRP
apparatus may be configured to include substantially no electrical
power storage elements. In some cases, where the inertia of the
rotatable element of the motor is insufficient to maintain a
constant input power without excessive speed variations, additional
inertia may be added to rotatable element of the motor.
[0017] A CRP apparatus or method, according to the invention, may
include operatively coupling a solar energy power source to a CRP
apparatus, according to the invention, for providing some or all of
the power for driving the motor. In some forms of the invention,
the CRP solar energy power source is the sole source of power for
driving the motor, such that the CRP apparatus only pumps when the
solar energy power source is producing sufficient power to drive
the motor. Those having skill in the art will recognize that the
capability of the invention to be practiced solely with a solar
energy power source without the need for any electrical power
storage elements, makes apparatuses and methods, according to the
invention, particularly desirable for use in remote locations
having little or no access to power lines or maintenance roads.
[0018] The invention may also take the form of a method for pumping
fluid from a source of fluid located in a remote location, by
operatively attaching a CRP apparatus, according to the invention,
to the source of the fluid. The method may further include
attaching the CRP apparatus to a stand-alone source of power, such
as an engine driven generator, a battery, or a solar collecting
array. In some forms of the invention, the stand-alone source of
power is a solar energy power source.
[0019] Some forms of a method, according to the invention, may
further include providing the source of fluid at the remote
location. Where the source of fluid at the remote location is a
fluid well, a method according to the invention may further include
providing the fluid well through steps such as drilling the well,
and/or uncapping an existing abandoned well.
[0020] Other aspects, objects and advantages of the invention will
be apparent from the following detailed description of the
accompanying drawings, photographs and other attachments.
BRIEF DESCRIPTION OF THE DRAWINGS AND ATTACHMENTS
[0021] The accompanying drawings and attachments incorporated in
and forming a part of the specification illustrate several aspects
of the present invention and, together with the description, serve
to explain the principles of the invention.
[0022] FIG. 1 is a schematic illustration of a first exemplary
embodiment of a crank rod pumping apparatus (CRP), according to the
invention, mounted to the wellhead of a hydrocarbon well.
[0023] FIG. 2 is a schematic illustration of the first exemplary
embodiment of the CRP pumping apparatus, according to the
invention, mounted on the wellhead of the well shown in FIG. 1, and
operatively connected for pumping fluid from the well, instead of
the walking beam apparatus, with the CRP pumping apparatus and
walking beam pumping apparatus being drawn to the same scale to
illustrate the substantial reduction in size and complexity of the
CRP pumping apparatus, according to the invention, as compared to
the walking beam apparatus which was providing similar pumping
output.
[0024] FIGS. 3 and 4 are perspective illustrations of a second
exemplary embodiment of a CRP apparatus, according to the
invention.
[0025] FIGS. 5-7 are schematic illustrations of the construction of
several alternate embodiments of a pneumatic counterbalance
arrangement, according to the invention.
[0026] FIGS. 8-10 are schematic illustrations showing additional
construction details and demonstrating the operation of several
alternate embodiments of pneumatic counterbalance arrangements,
according to the invention.
[0027] FIGS. 11-13 are perspective illustrations of a third
exemplary embodiment of a cranked rod pump apparatus, according to
the invention.
[0028] FIGS. 14-16 are perspective illustrations of a fourth
exemplary embodiment of a cranked rod pumping apparatus, according
to the invention.
[0029] FIG. 17 is a perspective illustration of a fifth exemplary
embodiment of a cranked rod pumping apparatus, according to the
invention.
[0030] FIGS. 18 and 19 are side views of the fifth exemplary
embodiment of a cranked rod pumping apparatus shown in FIG. 17,
with FIGS. 18 and 19 showing elements of the cranked rod pump in
two different positions during a cranking cycle of the cranked rod
pump, according to the invention.
[0031] While the invention will be described in connection with
certain preferred embodiments, there is no intent to limit it to
those embodiments. On the contrary, the intent is to cover all
alternatives, modifications and equivalents as included within the
spirit and scope of the invention.
DETAILED DESCRIPTION OF THE INVENTION
[0032] FIG. 1 is a schematic illustration showing an embodiment of
a cranked rod pump (CRP) apparatus 100 attached to a wellhead of a
hydrocarbon well. As shown in FIG. 1, the invention may be
practiced with a variety of power sources including a solar array
101 or through attachment to a conventional power grid 103.
[0033] FIG. 2 illustrates the manner in which a CRP apparatus 100,
according to the invention, may be utilized to great advantage for
replacing a conventional walking beam pumping apparatus 50. In FIG.
2, the cranked rod pumping apparatus 100 is mounted on the well
head 54 of a hydrocarbon well 56.
[0034] Returning to FIG. 1, the well includes a casing 60 which
extends downward into the ground through a subterranean formation
62 to a depth sufficient to reach an oil reservoir 64. The casing
60 includes a series of perforations 66, through which fluid from
the hydrocarbon reservoir enter into the casing 60, to thereby
provide a source of fluid for a down-hole pumping apparatus 68,
installed at the bottom of a length of tubing 70 which terminates
in an fluid outlet 72 at a point above the surface 74 of the
ground. The casing 60 terminates in a gas outlet 76 above the
surface of the ground 74.
[0035] The down-hole pumping apparatus 68 includes a stationary
valve 78, and a traveling valve 80. The traveling valve 80 is
attached to a rod string 82 extending upward through the tubing 70
and exiting the well head 54 at the polished rod 52. Those having
skill in the art will recognize that the down-hole pumping
apparatus 68, in the exemplary embodiment of the invention, forms a
traditional sucker-rod pump arrangement for lifting fluid from the
bottom of the well 56 as the polished rod 52 imparts reciprocal
motion to rod string 82 and the rod string 82 in turn causes
reciprocal motion of the traveling valve 80 through a pump stroke
84. In a typical hydrocarbon well, the rod string 82 may be several
thousand feet long and the pump stroke 84 may be several feet
long.
[0036] As shown in FIG. 1, the first exemplary embodiment of a
cranked rod pump apparatus 100, according to the invention,
includes a cranked mechanical actuator arrangement 102, a motor
104, and a control arrangement 106, with the control arrangement
106 including a controller 108 and a motor drive 110. A controller
and/or motor drive, according to the invention, may take a variety
of forms and include some or all of the apparatuses and methods
disclosed in commonly assigned: U.S. Pat. No. 7,168,924 B2, to Beck
et al., titled "Rod Pump Control System Including Parameter
Estimator"; and co-pending, U.S. patent application Ser. No.
11/380,861, titled "Power Variation Control System for Cyclic
Loads," to Peterson. The disclosures, teachings and suggestions of
the Beck '924 patent and the Peterson '861 patent application are
incorporated herein in their entireties by reference.
[0037] In all forms of the invention, the velocity and torque of
the motor are calculated from measurements of motor voltages and
currents. Crank velocity and torque are calculated allowing for the
ratio of the gear box. Position of the crank is determined by
integrating the crank velocity starting from a known reference
position. The reference may be determined from a reference switch
or by analyzing the pattern of the crank torque throughout the
rotation of the crank. Estimating the reference point takes
advantage of the fact that the loads on the crank at the top and
bottom of stroke are approximately zero and that these two points
are 180 degrees apart. Therefore, points in the crank rotation that
have approximately zero load, but are not 180 degrees separated
from a similar point may be ignored. The position of the rod is
determined by the position of the crank and the geometry of the CRP
apparatus.
[0038] FIGS. 3 and 4 illustrate a second exemplary embodiment of a
CRP apparatus 200, for imparting reciprocating substantially
vertical motion, as indicated by arrow 202 to a rod 204 of a
sucker-rod pump, such as the one illustrated as 100 in FIG. 1,
having a pump stroke 206. The exemplary embodiment of the CRP
apparatus 200 includes a cranked mechanical actuator arrangement
208 having a substantially vertically moveable member 210 attached
to the rod 204 of the sucker-rod pump for imparting and controlling
vertical motion of the rod 204 of the sucker-rod pump.
Specifically, in the exemplary embodiment 200, the rod 204 passes
through a through-hole (not shown) in an upper crossbar 212 of the
vertically moveable member 210, and is secured to the vertically
moveable member 210 by a clamp 214 which grips the rod 204 above
the vertically moveable member 210.
[0039] The first exemplary embodiment of the CRP apparatus 200 also
includes a motor 216 having a rotatable element (not shown) thereof
operatively connected in a manner described in more detail below to
the substantially vertically moveable member 210 of the linear
actuator arrangement 208.
[0040] As shown in FIGS. 3 and 4, the crank mechanical actuator
arrangement 208 in the exemplary embodiment 200 of the invention
includes a frame 218, having a base 220 adapted for attachment to
the wellhead of a well, and two linear guide rails 222, 224 which
extend vertically upward from the base 220, when the base 220 is
attached to wellhead. The vertically moveable member 210 is
slideably mounted, by linear bearings (not shown) on the linear
guides 222, 224 and constrained by the guides 222, 224 for
substantially linear reciprocating vertical movement along the
guides 222, 224 in the manner illustrated in FIGS. 3 and 4.
[0041] As shown in FIGS. 3 and 4, the exemplary embodiment of the
crank mechanical actuator arrangement 208 in the exemplary
embodiment of the CRP apparatus 200 includes a drive arrangement,
in the form of a right angle gear box 226, which is mounted on the
base 220. The rotatable element of the motor 216 is attached to a
vertically oriented input (not shown) of the gear box 226, and
converted to motion of a horizontally oriented output shaft 228 of
the gear box 226 by a gear train (not shown) within the gear box
226. In this manner, the rotatable element of the motor 216 is
operatively coupled in a fixed-ratio drive arrangement to the
output shaft 228 of the gear box. It will be further seen from
FIGS. 3 and 4 that the upper ends of the guides 222, 224 are joined
by an upper frame cross member 230, and that the frame 218 further
includes a motor mounting bracket 232 which extends downward from
the upper frame cross member 230 to provide support for the motor
216 in its vertically oriented position atop the gear box 226.
[0042] As further shown in FIGS. 3 and 4, the crank mechanical
actuator arrangement 208 of the first exemplary embodiment 200
includes a crank element 234 and an articulating link element 236.
As will be understood from FIGS. 3 and 4, the crank element 234 is
operatively coupled at a first attachment point thereof to the
rotatable element of the motor 216, by virtue of the
above-described attachment of the motor 216 to the gear box 226,
attachment of the first attachment point of the crank element to
the output shaft 228 of the gear box 226, such that the crank
element 234 rotates in a fixed drive ratio with the rotatable
element of the motor 216.
[0043] The articulating link element 236 has first and second
attachment points thereof, disposed at a spaced relationship from
one another along the articulating link element 236. The first
attachment point of the articulating link element 234 is pivotably
joined to the crank element 234 at a second attachment point of the
crank element 234 which is spaced eccentrically and radially
outward from the first attachment point of the cranked element 234.
The second attachment point of the articulating link element is
pivotably attached to the vertically moveable member 210.
[0044] Those having skill in the art will recognize that, by virtue
of the above-described arrangement, as the motor 216 drives the
output shaft of the gear box 226, the crank element rotates with
the output shaft of the gear box, passing on part of each stroke
through a slot in the base 220 and causes the articulating link
element 236 to drive the vertically moveable member 210 up and down
along the guides 222, 224 to thereby impart the reciprocating pump
stroke to the rod 204.
[0045] As will be noted from an examination of FIG. 4, the crank
element 234, in the exemplary embodiment 200, is essentially a
lever having an additional attachment point 235 for the
articulating link element 236, so that the stroke length 206 may be
varied by changing the attachment point to the crank element 234.
It will be further noted, by those having skill in the art, that
although a simple lever-like configuration was selected for use in
the exemplary embodiment 200, in other embodiments of the
invention, the crank element 234 may have other shapes, such as
triangular, square, or circular, and may also include additional
attachment points to provide for a wider selection of stroke
lengths. It will be yet further noted, that, in other embodiments
of the invention, the articulating link element 236 may also have
additional attachment points for use in adjusting stroke
length.
[0046] As shown in FIGS. 3 and 4, the cranked rod mechanical
actuator 208 of the exemplary embodiment of the CRP apparatus 200
also includes a pneumatic counterbalance arrangement 238, which
includes four pneumatic cylinders 239 operatively connected between
the frame 218 and the vertically moveable member 210, in addition
to other components which are operatively connected in a suitable
manner, such as those described in greater detail below hereto. As
will be understood, from a review of the drawings and description
given herein, the exemplary embodiment pneumatic counterbalance
arrangement 238 in the CRP apparatus 200 includes several pneumatic
cylinders 239 operatively connected between the base 220 and the
vertically moveable member 210 for storing energy during a portion
of the downward stroke of the vertically moveable member 210, and
for releasing the stored energy during a portion of a subsequent
upward stroke of the vertically moveable member 210. Addition of
the pneumatic counterbalance arrangement 238 results in the lifting
force available from the CRP apparatus being increased
substantially over the lifting capacity of a CRP apparatus,
according to the invention, which does not include the pneumatic
counterbalance arrangement 238.
[0047] In some cases, the available power, due to limitations in
the power source, electronic drive rating or mechanical limitations
of the apparatus, may not be sufficient to rotate the crank from a
fully lowered, stationary position through a full rotation. In
those cases, the crank is rotated in a first direction until the
rotational speed of the motor decreases, due to loading, below some
threshold. At this time, rotational direction is reversed to
command torque in the second, opposite direction. During each
iteration of this rocking action, energy is stored in the lifted
mass of the rod string, pump and fluid column. This energy is then
returned to the kinetic energy of the pump mechanism or into the
pressurization of the pneumatic counterbalance system as the lifted
mass is lowered. In this way, the crank pump mechanism will achieve
greater and greater speed and inertia and/or the counterbalance
will support more and more of the weight of the fluid column, rod
string and downhole pump mechanism each time it passes through the
fully lowered position, until the combined inertia,
counterbalancing and available power are sufficient to rotate the
mechanism through a full cycle. From this point the mechanism
continues in a single rotational direction.
[0048] FIG. 5 is a schematic illustration of a portion of the CRP
apparatus 200, illustrating the placement of a pair of pneumatic
cylinders 239 of the pneumatic counterbalance arrangement 238
configured as shown and discussed above with regard to FIGS. 3 and
4. Specifically, in the configuration shown in FIGS. 3-5, the rod
240 of the cylinders 239 is operatively attached to the upper
crossbar 212, and the base of the cylinders 239 is attached to the
base 220 of the frame 218. Those having skill in the art will
recognize, however, that a pneumatic counterbalance arrangement
according to the invention may take a variety of other forms, such
as those illustrated schematically in FIG. 6 and FIG. 7. In FIG. 7,
the cylinders 239 are mounted on the upper frame cross member 230
with the rods 240 of the cylinders 239 extending downward into
operative contact with the upper crossbar 212. FIG. 7 illustrates
an alternate placement of the cylinders 239 between the upper frame
cross member and the moveable upper crossbar 212.
[0049] It is contemplated that, in addition to alternate mounting
arrangements for the pneumatic cylinders 239, the number of
cylinders utilized in any given application may also be greater or
less than that shown in FIGS. 3-7, in various embodiments of the
invention. It is also contemplated that it will generally be
advantageous to have a working axis of the cylinders 239 aligned as
closely as possible with the polished rod 204, so that the
counterbalance forces generated by the cylinders are operatively
transmitted as directly as possible to the polished rod 204.
[0050] FIGS. 8-10 are schematic illustrations of several alternate
embodiments of a pneumatic counterbalance arrangement 238,
according to the invention. It will be recognized that the
embodiments shown in FIGS. 8-10 are illustrative of the general
principles of construction and operation of a pneumatic
counterbalance arrangement according to the invention but are by no
means intended to be limiting. Those having skill in the art will
recognize that there are many other ways of constructing and
operating a pneumatic counterbalance arrangement within the
contemplated scope of the invention. It is further noted that the
embodiments shown in FIGS. 8-10 all operate on a "bootstrap"
principle, in which air is drawn into the cylinder 239 and trapped
in a volume below a piston 242 of the cylinder 239 by virtue of
reciprocating movements imparted to the rod 240 of the cylinder 239
by upward movement of the upper crossbar 212 in combination with
the operation of an inlet check valve 244. Repetitive cycling of
the piston 242 up and down results in a counterbalance pressure
being built up on the cylinder 239 below the piston which then
exerts an upward force on the piston 242 which is transmitted
through the rod 240 as an upward counterbalancing force against
downward movement of the upper crossbar 212. This resultant
counterbalancing force acts against the weight of the rod and
pumping mechanism on the downward stroke of the pump and further
acts to assist the CRP apparatus in pulling the rod 204 upward on a
successive stroke.
[0051] In the embodiment shown in FIG. 8, as the rod 240 pulls the
piston 242 upward on an upward stroke of the CRP apparatus 200, the
inlet check valve 244 opens and allows a flow of air into the
cylinder 239 in a lower chamber having a volume defined by the
space between the piston 242 and the inlet check valve 244. When
the piston 242 reaches the top of its stroke and begins to move
downward on its downward stroke, the check valve 244 closes and
traps the ingested air between the piston 242 and the inlet check
valve 244. As the piston 242 continues to move downward, the space
between the piston 242 and the inlet check valve 244 becomes
smaller, which causes the pressure of the air trapped between the
piston 242 and the inlet check valve 244 to increase. This increase
in pressure results in a storage of energy which is then released
on the successive upstroke as the piston 242 moves upward to
thereby generate the counterbalancing force aiding the CRP
apparatus in raising the rod 204 on its upstroke. As a practical
matter, with the arrangement shown in FIG. 8 it may take a rocking
action as described above to allow the pressure between the piston
242 and the check valve 244 at the bottom of the pump stroke 206 to
"bootstrap" up to a maximum working value. The inlet check valve
244 will continuously open to replenish any air leaking past the
piston 242 during operation of the CRP apparatus. In the embodiment
of FIG. 8, the cylinder 239 may be either a single acting or a
double acting cylinder.
[0052] The exemplary embodiment of the pneumatic counterbalance
arrangement 238 shown in FIG. 9 is essentially identical to the
embodiment shown in FIG. 8 and described above, with the exception
that in the embodiment of FIG. 9 the pneumatic counterbalance
arrangement 238 also includes an outlet check valve 246 and the
cylinder 239 is a double acting cylinder. Operation of the
embodiment shown in FIG. 9 is essentially the same as operation of
the previously described embodiment of FIG. 8, with the exception
of the action of the outlet check valve 246. As will be understood
from an examination of FIG. 9, whereas the inlet check valve 244 is
configured to allow air to be drawn into the cylinder 239 as the
piston moves upward and to close and trap air between the piston
242 and the inlet check valve 244 on the downward stroke of the
piston, the outlet check valve 246 is configured to allow air to
exit the space between the piston 242 and the outlet check valve
246 as the piston 242 moves upward, and prevent entry back into the
space between the piston 242 and the outlet check valve 246 as the
piston 242 moves downward. By virtue of this arrangement, as the
piston 242 is reciprocated within the cylinder 239, in addition to
pressure being built up in the space below the piston 242 pressure
above the piston 242 is reduced below atmospheric as the piston 242
is forced downward by the action of the upper crossbar 212 on the
piston rod 240. This arrangement provides an advantage in that the
embodiment of FIG. 9 generates a greater pressure differential and
resultant counterbalancing force across the piston 242 than is
generated in the embodiment shown in FIG. 8.
[0053] FIG. 10 illustrates yet another alternate embodiment of a
pneumatic counterbalance arrangement 238, according to the
invention. In simple terms, the embodiment shown in FIG. 10
combines a cylinder 239 having inlet and outlet check valves 244,
246 arranged in operating as described above with regard to the
embodiment of FIG. 9, with an additional pumping cylinder 248
having a configuration and operation similar to that described
above with regard to the embodiment of FIG. 8.
[0054] The pumping cylinder 248 includes a piston 250 driven by a
piston rod 252 which is operatively connected to the upper crossbar
212 to operate substantially in a parallel manner to the piston rod
240 of the piston 239. A second inlet check valve 254 is provided
to allow air to be drawn into both the cylinder 248 and the
cylinder 239 beneath their respective pistons 250 and 242 on a
first upstroke of the CRP apparatus 200. On subsequent upstrokes,
the pressure in reservoir cavity 256 would exceed the pressure in
pumping cavity 258, causing check valve 244 to remain closed. On a
downward stroke of the CRP apparatus 200, the pistons 242 and 250
compress the air in the pumping cavity 258 and the reservoir cavity
256. As the air in the pumping cavity 258 compresses, it will
exceed atmospheric pressure, causing inlet check valve 254 to
close. The air in the pumping cavity 258 will continue to compress
and, due to its relatively smaller volume, will compress to a
higher pressure than the air in the reservoir cavity 256. When this
occurs, check valve 244 will open and allow the higher pressure air
to enter the reservoir cavity 256. As the CRP apparatus 200
reciprocates, the reciprocal motion of the pistons 242 and 250
results in pressure above atmospheric being built up in the
reservoir cavity 256. By raising the pressure at the inlet to the
first inlet check valve 244 above atmospheric, a higher
counterbalance pressure may be built up in the reservoir cavity 256
of the embodiment shown in FIG. 10 than can be achieved with the
embodiments of FIG. 8 and FIG. 9 in which the pressure upstream of
the inlet check valve 244 is limited to atmospheric pressure. It
will also be appreciated that the pressure generated in the pumping
cavity 258 will contribute to the counterbalance effect and be
transmitted through the rod 252 of the pumping cylinder 248 to the
upper crossbar 212. As a practical matter, with the arrangement
shown in FIG. 10 it may take several strokes of the CRP apparatus
200, or a rocking action as described above, to allow the pressure
between the piston 242 and the check valve 244 at the bottom of the
pump stroke 206 to "bootstrap" up to a maximum working value.
[0055] As shown in FIG. 10, it may be desirable to add an air tank
260 at an appropriate position within a pneumatic counterbalance
arrangement according to the invention, in order to improve
operation. It may also be advantageous to provide some form of
pressure gage or sensor 262 at an appropriate location for
monitoring and controlling operating pressures in the reservoir
cavity 256, the pumping cavity 258, and the cavity between the
piston 242 and the outlet check valve 246 using a controller 264.
It will be recognized that the controller 264 may take any
appropriate form, including manual or automatic controls.
[0056] FIGS. 11-13 illustrate a third exemplary embodiment of a CRP
apparatus 300, in accordance with the invention. The third
exemplary embodiment of the CRP apparatus 300 is substantially
identical to the second exemplary embodiment of the CRP apparatus
200, described above, with the exception that the third exemplary
embodiment of the CRP apparatus 300 does not include a pneumatic
counterbalance arrangement. FIGS. 11-13 illustrate an upper
crossbar 312, an articulating link element 336, and a crank element
334 of the third exemplary embodiment of the CRP apparatus 300 in
different positions during a pump stroke 306.
[0057] FIGS. 14-16 illustrate a fourth exemplary embodiment of a
CRP apparatus 400, according to the invention. The construction of
the fourth exemplary embodiment of the CRP apparatus 400 is similar
in most respects to the embodiments described hereinabove. The
primary difference between the fourth exemplary embodiment 400 and
the previous exemplary embodiments lies in mounting the motor 416
and right angle gear box 420 on top of the upper frame cross member
430 of the frame 418, rather than mounting the motor and gear box
216 and 226 to the base 220 of the frame 218 in the second and
third exemplary embodiments of the CRP apparatus 200, 300. FIGS.
14-16 show a vertically moveable member 410, a crank element 434
and an articulating link element 436 of the CRP apparatus 400 in
several different positions during a pump stroke 406.
[0058] FIGS. 17-19 illustrate a fifth exemplary embodiment of a CRP
apparatus 500, according to the invention. The construction of the
fifth exemplary embodiment of the CRP apparatus 500 is similar in
many respects to the other embodiments of CRP apparatuses described
hereinabove. The primary difference between the fifth exemplary
embodiment 500 and the previous exemplary embodiments lies in
mounting the motor 516 and right angle gear box 526 on one side of
a vertical guide rail member 519, of the frame 518, having one or
more linear guide rails 522, 524 on an opposite side of the guide
rail member 519 from the motor 516 and gearbox 526 for guiding a
vertically movable member 510 along the linear guide rails 522,
524. The vertically movable member 510 is operatively connected by
a crank element 534 and an articulating link element 536 and the
right angle gearbox 520 to a rotatable element of the motor 516, in
the form of a motor output shaft (not shown). By virtue of this
arrangement, the rotatable element of the motor 516 and the
vertically movable member 510 are operatively connected in a fixed
relationship to one another.
[0059] FIGS. 18 and 19 respectively show the vertically moveable
member 510, at the low end and the high end of a pump stroke 506 of
the CRP apparatus 500. The respective lengths of the crank element
534 and an articulating link element 536 of the CRP apparatus, and
the vertical location of the right angle gearbox 526 above a base
520 of the frame 518 are cooperatively selected so that the
vertically movable member 510 will always hang below the upper end
of the articulating link 536 in any angular position of the crank
element 534, during operation of the CRP apparatus 500. As a result
having the vertically movable member 510 always hang below the
upper end of the articulating link 536 in any angular position of
the crank element 534, in combination with positioning the gearbox
526 and vertically movable member 510 on opposite sides of the
vertical guide rail member 519, gravitational forces will cause the
vertically movable member 510 to be slidingly held in contact with
the linear guide rails 522, 524 of the vertical guide rail member
519, as the motor 516 is controlled to impart reciprocating motion
to the vertically movable member 510 along the linear guide rails
522, 524.
[0060] As best seen in FIG. 17, the pump rod 504 extends slidingly
through and is secured to the vertically movable member 510 in the
exemplary embodiment of the CRP apparatus by a clamp 514 located
above the vertically movable member 510, in the same manner as
described above in relation to other embodiments of the invention.
As further shown in FIG. 17, the vertically movable member 520 of
the CRP apparatus 500 includes bearing arrangements, roller bearing
arrangements 511, for reducing frictional contact of the vertically
movable member 510 with the linear guide rails 522, 524.
[0061] It will be understood that a pneumatic counterbalance
arrangement, according to the invention may also be used in a CRP
apparatus similar to the fifth exemplary embodiment of the
invention, in other embodiments of the invention.
[0062] All references, including publications, patent applications,
and patents cited herein are hereby incorporated by reference to
the same extent as if each reference were individually and
specifically indicated to be incorporated by reference and were set
forth in its entirety herein.
[0063] The use of the terms "a" and "an" and "the" and similar
referents in the context of describing the invention (especially in
the context of the following claims) is to be construed to cover
both the singular and the plural, unless otherwise indicated herein
or clearly contradicted by context. The terms "comprising,"
"having," "including," and "containing" are to be construed as
open-ended terms (i.e., meaning "including, but not limited to,")
unless otherwise noted. Recitation of ranges of values herein are
merely intended to serve as a shorthand method of referring
individually to each separate value falling within the range,
unless otherwise indicated herein, and each separate value is
incorporated into the specification as if it were individually
recited herein. All methods described herein can be performed in
any suitable order unless otherwise indicated herein or otherwise
clearly contradicted by context. The use of any and all examples,
or exemplary language (e.g., "such as") provided herein, is
intended merely to better illuminate the invention and does not
pose a limitation on the scope of the invention unless otherwise
claimed. No language in the specification should be construed as
indicating any non-claimed element as essential to the practice of
the invention.
[0064] Preferred embodiments of this invention are described
herein, including the best mode known to the inventors for carrying
out the invention. Variations of those preferred embodiments may
become apparent to those of ordinary skill in the art upon reading
the foregoing description. The inventors expect skilled artisans to
employ such variations as appropriate, and the inventors intend for
the invention to be practiced otherwise than as specifically
described herein. Accordingly, this invention includes all
modifications and equivalents of the subject matter recited in the
claims appended hereto as permitted by applicable law. Moreover,
any combination of the above-described elements in all possible
variations thereof is encompassed by the invention unless otherwise
indicated herein or otherwise clearly contradicted by context.
* * * * *