U.S. patent application number 16/395855 was filed with the patent office on 2019-10-31 for well service pump systems and related methods.
The applicant listed for this patent is AMERIFORGE GROUP INC.. Invention is credited to Shelton BURNETT, Tom GABLE, Eric MARTIN, Lyle MEYER, Garrett Smith.
Application Number | 20190330923 16/395855 |
Document ID | / |
Family ID | 66476842 |
Filed Date | 2019-10-31 |
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United States Patent
Application |
20190330923 |
Kind Code |
A1 |
GABLE; Tom ; et al. |
October 31, 2019 |
WELL SERVICE PUMP SYSTEMS AND RELATED METHODS
Abstract
A well service pump system supplies high pressure working fluid
to a well. The pump system includes a closed-loop hydraulic circuit
for actuating a plurality of working pump assemblies. The pump
system is powered by a motor, which transfers mechanical energy to
a plurality of pumps, which, in turn, provide hydraulic fluid to
operate hydraulic ram cylinders, and thereby operate the working
pump assemblies. Each of the polished rods of the hydraulic ram
cylinders is connected axially to a plunger rod end of the working
fluid end cylinder to operate the working pump assembly.
Inventors: |
GABLE; Tom; (Houston,
TX) ; Smith; Garrett; (Houston, TX) ; BURNETT;
Shelton; (Houston, TX) ; MARTIN; Eric;
(Houston, TX) ; MEYER; Lyle; (Houston,
TX) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
AMERIFORGE GROUP INC. |
Houston |
TX |
US |
|
|
Family ID: |
66476842 |
Appl. No.: |
16/395855 |
Filed: |
April 26, 2019 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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62664072 |
Apr 27, 2018 |
|
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
E21B 43/129 20130101;
F04B 2205/501 20130101; E21B 4/14 20130101; F04B 53/008 20130101;
F04B 9/113 20130101; F04B 17/06 20130101; E21B 47/009 20200501;
F04B 23/06 20130101; E21B 44/005 20130101 |
International
Class: |
E21B 4/14 20060101
E21B004/14; E21B 47/00 20060101 E21B047/00; E21B 43/12 20060101
E21B043/12 |
Claims
1. A well service pump system for delivering working fluid at high
pressure to a well, the pump system comprising: at least two
working fluid pump assemblies, each comprising: a working fluid end
cylinder having a plunger rod configured to reciprocate within the
fluid end cylinder; and a hydraulic ram cylinder having a ram
piston configured to reciprocate within the ram cylinder and a
piston rod coupled to the ram piston and coupled to the plunger rod
of the working fluid end cylinder such that the ram piston of the
hydraulic ram cylinder can be actuated to move the plunger rod of
the working fluid end cylinder: in a first direction to expel
working fluid from the fluid end cylinder during a forward stroke
of the plunger rod, and in a second direction to draw working fluid
into the fluid end cylinder during a return stroke of the plunger
rod; wherein the hydraulic ram cylinder includes a first hydraulic
port on a first side of the ram piston and a second hydraulic port
on a second side of the ram piston; a plurality of bi-directional
pumps, each coupled to a respective one of the working fluid pump
assemblies such that the bi-directional pump is in fluid
communication with the first hydraulic port and the second
hydraulic port of the hydraulic ram cylinder to pump hydraulic
fluid: from the second hydraulic port directly into the first
hydraulic port to actuate the ram piston to drive the plunger rod
in the first direction; and from the first hydraulic port directly
into the second hydraulic port to actuate the ram piston to drive
the plunger rod in the second direction.
2. The well service pump system of claim 1, comprising a fluid
reservoir configured to be in fluid communication with each of the
plurality of bi-directional pumps to compensate for leakage in the
system.
3. The well service pump system of claim 1, wherein, when the ram
piston of the hydraulic ram cylinder reciprocates within the
hydraulic ram cylinder, the ram piston is, at all times, spaced a
distance from a first end wall of the hydraulic ram cylinder and a
second end wall of the hydraulic ram cylinder opposite the first
end wall.
4. The well service pump system of claim 1, comprising a motor
configured to drive each of the bi-directional pumps to direct
fluid to the first and second ports.
5. The well service pump system of claim 4, comprising a pump drive
coupled to the motor and to each of the bi-directional pumps, the
pump drive configured to transfer mechanical energy from the motor
to each of the bi-directional pumps.
6. The well service pump system of claim 5, wherein at least one of
the bi-directional pumps is mounted to the pump drive.
7. The well service pump system of claim 4, wherein the motor
comprises an electric motor.
8. The well service pump system of claim 1, wherein, for at least
one of the working fluid pump assemblies, the ram piston has an
actuatable piston surface area that is at least two times greater
than an actuatable piston surface area of the plunger rod.
9. The well service pump system of claim 1, wherein each working
fluid pump assembly further comprises a coupling member coupled to
the plunger rod of the working fluid end cylinder and to the piston
rod of the hydraulic ram cylinder.
10. The well service pump system of claim 1, wherein in each
working fluid pump assembly, the piston rod of the hydraulic ram
cylinder is axially aligned with the plunger rod of the hydraulic
ram cylinder.
11. The well service pump system of claim 1, wherein in each
working fluid pump assembly, the working fluid end cylinder has a
cylindrical inner wall and the plunger rod has an outer surface
that is spaced apart from the cylindrical inner wall such that the
working fluid end cylinder can pump abrasive fluids without the
plunger rod and the cylinder inner wall simultaneously contacting
individual particles in the working fluid.
12. The well service pump system of claim 1, wherein at least one
of the hydraulic pumps comprises a fixed-displacement hydraulic
pump.
13. The well service pump system of claim 1, wherein each working
fluid pump assembly further comprises: an inlet check valve coupled
to the fluid end cylinder and configured to permit working fluid to
be drawn into the fluid end cylinder but prevent working fluid from
exiting the fluid end cylinder through the inlet check valve; and
an outlet check valve coupled to the fluid end cylinder and
configured to permit working fluid to exit the fluid end cylinder
while preventing working fluid from being drawn into the fluid end
cylinder through the outlet check valve.
14. The well service pump system of claim 13, wherein, for at least
one of the working fluid pump assemblies, the working fluid is
pressurized when it enters the fluid end cylinder through the inlet
check valve.
15. A method comprising: delivering a working fluid to a well with
a well service pump system comprising: at least two working fluid
pump assemblies, each comprising: a working fluid end cylinder
having a plunger rod configured to reciprocate within the fluid end
cylinder; and a hydraulic ram cylinder having a ram piston
configured to reciprocate within the hydraulic ram cylinder and a
piston rod coupled to the ram piston and coupled to the plunger rod
of the working fluid end cylinder; wherein the hydraulic ram
cylinder includes a first hydraulic port on a first side of the ram
piston and second hydraulic port on a second side of the ram
piston; a plurality of bi-directional pumps, each fluidly coupled
to a respective one of the working fluid pump assemblies; wherein
delivering the working fluid comprises: actuating the ram piston of
the hydraulic ram cylinder to move the plunger rod of the working
fluid end cylinder: in a first direction to expel working fluid
from the fluid end cylinder during a forward stroke of the plunger
rod, and in a second direction to draw working fluid into the fluid
end cylinder during a return stroke of the plunger rod; and
directing hydraulic fluid, via the bi-directional pump: from the
second hydraulic port directly into the first hydraulic port to
actuate the ram piston to drive the plunger rod in the first
direction; and from the first hydraulic port directly into the
second hydraulic port to actuate the ram piston to drive the
plunger rod in the second direction.
16. The method of claim 15, comprising actuating a motor to drive
each of the bi-directional pumps to direct fluid to the first and
second ports.
17. The method of claim 16, wherein the motor comprises an electric
motor.
18. The method of claim 15, wherein at least one of the hydraulic
pumps comprises a fixed-displacement hydraulic pump.
19. The well service pump system of claim 4, wherein the motor
comprises a combustion engine.
20. The method of claim 16, wherein the motor comprises a
combustion engine.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority to U.S. Provisional
Application No. 62/664,072, filed Apr. 27, 2018, the entire
contents of which application are specifically incorporated by
reference herein without disclaimer.
FIELD OF INVENTION
[0002] The present invention relates generally to pumping
assemblies used for well servicing applications, most particularly
pumping assemblies used for well fracturing operations.
DESCRIPTION OF RELATED ART
[0003] Oil and gas wells require services such as fracturing,
acidizing, cementing, sand control, well control and circulation
operations. All of these services require pumps for pumping fluid
down the well. The type of pump that has customarily been used in
the industry for many years is a gear driven plunger type, which
may be referred to as a "frac pump." The pump is often powered by a
diesel engine, typically 2,000 bhp or larger, that transfers its
power to a large automatic transmission. The automatic transmission
then transfers the power through a large driveline, into a gear
reduction box mounted on the frac pump. The frac pump has a
crankshaft mounted in a housing. A plunger has a crosshead that is
reciprocally carried in a cylinder perpendicular to the crankshaft.
A connecting rod connects each eccentric portion or journal of the
crankshaft to the plunger. The driveline enters the frac pump at a
right angle to the connecting rods, plungers and pump discharge. A
typical pump might be, for example, a triplex type having three
cylinders, three connecting rods, and three journals on the
crankshaft. An example of a common type of a well service pump
(e.g., plunger pump) is disclosed in U.S. Pat. No. 2,766,701 to
Giraudeau. Typical commercially available pumps include the
Weir/SPM.TM. line of pumps, for example, the QWS 2500 Classic.TM.
Well Service Pump and the Destiny TWS2500.TM. Well Service
Pump.
[0004] There are a number of known problems with the prior art
plunger pumps of the type under consideration. These pumps will
typically be mounted on a trailer or skid back-to-back. The frac
pumps are mounted at a right angle to the engine, transmission and
driveline. Each pump has an outboard side connected to a manifold
with valves for drawing in and pumping fluid acted on by the
plunger. The inboard sides will be located next to each other. The
overall width from one manifold to the other manifold should not
exceed roadway requirements, e.g., Department of Transportation
(DOT) rules and regulations. If the pumps are to be trailer mounted
for highway transport, this distance will be on the order of about
eight and one half feet. As a result, this necessarily means that
the frac units which are trailer mounted will be restricted in size
by the applicable DOT rules and regulations. The current plunger
stroke length for present day frac pumps is typically 8 to 10
inches. However, in order to meet DOT requirements, some
manufacturers have reduced the size of the pump, for example
reducing the pump stroke, in some cases down to as much as four to
six inches.
[0005] However, reducing the stroke length of the plungers is not
an ideal solution to the problem and, in fact, offers a number of
disadvantages in the design. Ideally, it would be desirable to
lengthen the stroke of these pumps instead of shortening the stroke
length, in order to reduce cycles per minute in use. This is due to
the fact that there is a tremendous failure rate in current frac
pump fluid ends, due to cyclic fatigue. The increased failure rate
results from increased demand placed upon today's frac pumps, as
compared to the practice in prior years. An example of a typical
frac job in shale formations today would be a five hour pump time.
During this pump time the plunger cycles would be, for example, 250
per minute at 10,000 psi. There has not been a great deal of change
in the design of basic frac pumps going back some fifty years.
However, the prior art designs of fifty years ago were intended for
frac jobs that might last up to 2 hours. The unit would then
typically be shut down until the next day. During today's frac
jobs, for example in commonly encountered shale formations, the
units are pumping 4-8 hours at higher pressures than in the past.
The units are then typically shut down for an hour or two and then
started up again for another stage for approximately the same
duration. This type of operation may exceed the intended design
limits of the units.
[0006] It has also been attempted in the past, especially with the
larger oil field pumps, to increase the stroke length by offsetting
the crankshaft axis with the cylinder axis. The offset is selected
so that during the power or output stroke, the centerline of the
crankshaft end of the connecting rod will be located closer to the
cylinder axis than the crankshaft axis. Matzner et al. disclose
vertically offsetting the cylinder axis from the crankshaft axis in
U.S. Pat. No. 5,246,355. It has also been attempted for the axis of
the wrist pin of the connecting rod to be vertically offset from
the cylinder axis to achieve the width requirements. An example of
a plunger pump having an offset wrist pin is disclosed in U.S. Pat.
No. 5,839,888 to Harrison. However, these designs still suffer from
all of the problems of having the frac pump mounted at a right
angle to the engine, transmission and driveline. They also fail to
reduce the mechanical complexity of the system and, in fact, likely
increase the complexity.
[0007] With prior art designs, it will be very difficult to
increase the plunger stroke length much more than 10 to 12 inches.
For example, increasing the stroke length by one inch may
necessitate increasing total length of the frac pump by at least
two inches due to the crankshaft design. This can put frac pumps in
violation of DOT standards regarding the width of the trailer
mounted frac unit, since the pump sits at a right angle to the
engine, transmission and driveline.
[0008] For these and other reasons, a need continues to exist for
improvements in oil and gas well servicing pumps of the type under
consideration.
SUMMARY
[0009] The present disclosure includes embodiments of pump systems
and methods.
[0010] Some embodiments of the present well service pump systems,
for delivering working fluid at high pressure to a well, comprise
at least two working fluid pump assemblies, each comprising: a
working fluid end cylinder having a plunger rod configured to
reciprocate within the fluid end cylinder; and a hydraulic ram
cylinder having a ram piston configured to reciprocate within the
ram cylinder and a piston rod coupled to the ram piston and coupled
to the plunger rod of the working fluid end cylinder such that the
ram piston of the hydraulic ram cylinder can be actuated to move
the plunger rod of the working fluid end cylinder: in a first
direction to expel working fluid from the fluid end cylinder during
a forward stroke of the plunger rod, and in a second direction to
draw working fluid into the fluid end cylinder during a return
stroke of the plunger rod; wherein the hydraulic ram cylinder
includes a first hydraulic port on a first side of the ram piston
and a second hydraulic port on a second side of the ram piston; a
plurality of bi-directional pumps, each coupled to a respective one
of the working fluid pump assemblies such that the bi-directional
pump is in fluid communication with the first hydraulic port and
the second hydraulic port of the hydraulic ram cylinder to pump
hydraulic fluid: from the second hydraulic port directly into the
first hydraulic port to actuate the ram piston to drive the plunger
rod in the first direction; and from the first hydraulic port
directly into the second hydraulic port to actuate the ram piston
to drive the plunger rod in the second direction.
[0011] Some embodiments of the present systems comprise a fluid
reservoir configured to be in fluid communication with each of the
plurality of bi-directional pumps to compensate for leakage in the
system.
[0012] In some embodiments of the present systems, when the ram
piston of the hydraulic ram cylinder reciprocates within the
hydraulic ram cylinder, the ram piston is, at all times, spaced a
distance from a first end wall of the hydraulic ram cylinder and a
second end wall of the hydraulic ram cylinder opposite the first
end wall.
[0013] Some embodiments of the present systems comprise a motor
configured to drive each of the bi-directional pumps to direct
fluid to the first and second ports.
[0014] Some embodiments of the present systems comprise a pump
drive coupled to the motor and to each of the bi-directional pumps,
the pump drive configured to transfer mechanical energy from the
motor to each of the bi-directional pumps. In some embodiments of
the present systems, at least one of the bi-directional pumps is
mounted to the pump drive. In some embodiments of the present
systems, the motor comprises an electric motor and/or a combustion
engine.
[0015] In some embodiments of the present systems, for at least one
of the working fluid pump assemblies, the ram piston has an
actuatable piston surface area that is at least two times greater
than an actuatable piston surface area of the plunger rod.
[0016] In some embodiments of the present systems, each working
fluid pump assembly further comprises a coupling member coupled to
the plunger rod of the working fluid end cylinder and to the piston
rod of the hydraulic ram cylinder. In some embodiments of the
present systems, in each working fluid pump assembly, the piston
rod of the hydraulic ram cylinder is axially aligned with the
plunger rod of the hydraulic ram cylinder. In some embodiments of
the present systems, each working fluid pump assembly, the working
fluid end cylinder has a cylindrical inner wall and the plunger rod
has an outer surface that is spaced apart from the cylindrical
inner wall such that the working fluid end cylinder can pump
abrasive fluids without the plunger rod and the cylinder inner wall
simultaneously contacting individual particles in the working
fluid. In some embodiments of the present systems, at least one of
the hydraulic pumps comprises a fixed-displacement hydraulic
pump.
[0017] In some embodiments of the present systems, each working
fluid pump assembly further comprises: an inlet check valve coupled
to the fluid end cylinder and configured to permit working fluid to
be drawn into the fluid end cylinder but prevent working fluid from
exiting the fluid end cylinder through the inlet check valve; and
an outlet check valve coupled to the fluid end cylinder and
configured to permit working fluid to exit the fluid end cylinder
while preventing working fluid from being drawn into the fluid end
cylinder through the outlet check valve. In some embodiments of the
present systems, for at least one of the working fluid pump
assemblies, the working fluid is pressurized when it enters the
fluid end cylinder through the inlet check valve.
[0018] Some embodiments of the present methods comprise delivering
a working fluid to a well with a well service pump system
comprising: at least two working fluid pump assemblies, each
comprising: a working fluid end cylinder having a plunger rod
configured to reciprocate within the fluid end cylinder; and a
hydraulic ram cylinder having a ram piston configured to
reciprocate within the hydraulic ram cylinder and a piston rod
coupled to the ram piston and coupled to the plunger rod of the
working fluid end cylinder; wherein the hydraulic ram cylinder
includes a first hydraulic port on a first side of the ram piston
and second hydraulic port on a second side of the ram piston; a
plurality of bi-directional pumps, each fluidly coupled to a
respective one of the working fluid pump assemblies; wherein
delivering the working fluid comprises: actuating the ram piston of
the hydraulic ram cylinder to move the plunger rod of the working
fluid end cylinder: in a first direction to expel working fluid
from the fluid end cylinder during a forward stroke of the plunger
rod, and in a second direction to draw working fluid into the fluid
end cylinder during a return stroke of the plunger rod; and
directing hydraulic fluid, via the bi-directional pump: from the
second hydraulic port directly into the first hydraulic port to
actuate the ram piston to drive the plunger rod in the first
direction; and from the first hydraulic port directly into the
second hydraulic port to actuate the ram piston to drive the
plunger rod in the second direction.
[0019] Some embodiments of the present systems comprise actuating a
motor to drive each of the bi-directional pumps to direct fluid to
the first and second ports. In some embodiments of the present
methods, the motor comprises an electric motor and/or a combustion
engine. In some embodiments of the present methods, at least one of
the hydraulic pumps comprises a fixed-displacement hydraulic
pump.
[0020] The term "coupled" is defined as connected, although not
necessarily directly, and not necessarily mechanically; two items
that are "coupled" may be unitary with each other. The terms "a"
and "an" are defined as one or more unless this disclosure
explicitly requires otherwise. The term "substantially" is defined
as largely but not necessarily wholly what is specified (and
includes what is specified; e.g., substantially 90 degrees includes
90 degrees and substantially parallel includes parallel), as
understood by a person of ordinary skill in the art. In any
disclosed embodiment, the terms "substantially," "approximately,"
and "about" may be substituted with "within [a percentage] of" what
is specified, where the percentage includes 0.1, 1, 5, and 10
percent.
[0021] The phrase "and/or" means and or or. To illustrate, A, B,
and/or C includes: A alone, B alone, C alone, a combination of A
and B, a combination of A and C, a combination of B and C, or a
combination of A, B, and C. In other words, "and/or" operates as an
inclusive or.
[0022] The terms "comprise" (and any form of comprise, such as
"comprises" and "comprising"), "have" (and any form of have, such
as "has" and "having"), "include" (and any form of include, such as
"includes" and "including"), and "contain" (and any form of
contain, such as "contains" and "containing") are open-ended
linking verbs. As a result, an apparatus that "comprises," "has,"
"includes," or "contains" one or more elements possesses those one
or more elements, but is not limited to possessing only those
elements. Likewise, a method that "comprises," "has," "includes,"
or "contains" one or more steps possesses those one or more steps,
but is not limited to possessing only those one or more steps.
[0023] Any embodiment of any of the apparatuses, systems, and
methods can consist of or consist essentially of--rather than
comprise/include/contain/have--any of the described steps,
elements, and/or features. Thus, in any of the claims, the term
"consisting of" or "consisting essentially of" can be substituted
for any of the open-ended linking verbs recited above, in order to
change the scope of a given claim from what it would otherwise be
using the open-ended linking verb.
[0024] The feature or features of one embodiment may be applied to
other embodiments, even though not described or illustrated, unless
expressly prohibited by this disclosure or the nature of the
embodiments.
[0025] Further, a device or system that is configured in a certain
way is configured in at least that way, but it can also be
configured in other ways than those specifically described.
[0026] Some details associated with the embodiments described above
and others are described below.
BRIEF DESCRIPTION OF THE DRAWINGS
[0027] FIG. 1 depicts a first perspective view of one embodiment of
the present well service pump systems.
[0028] FIG. 2 depicts a second perspective view of the system of
FIG. 1.
[0029] FIGS. 3 and 4 depict perspective views of various components
of the system of FIG. 1.
[0030] FIGS. 5 and 6 depict first and second perspective views of
working pump assemblies suitable for use with some embodiments of
the system of FIG. 1.
[0031] FIG. 7 depicts a cross-sectional side view of an embodiment
of the working pump assemblies of FIGS. 5 and 6.
[0032] FIG. 8 depicts a schematic of a closed-loop hydraulic
circuit, suitable for use with some embodiments of the system of
FIG. 1.
DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS
[0033] The following drawings illustrate by way of example and not
limitation. For the sake of brevity and clarity, every feature of a
given structure is not always labeled in every figure in which that
structure appears. Identical reference numbers do not necessarily
indicate an identical structure. Rather, the same reference number
may be used to indicate a similar feature or a feature with similar
functionality, as may non-identical reference numbers. The figures
are drawn to scale (unless otherwise noted), meaning the sizes of
the depicted elements are accurate relative to each other for at
least the embodiment depicted in the figures.
[0034] Referring now to the figures, and more particularly, to
FIGS. 1 and 2, shown therein and designated by reference numeral 10
is an embodiment of the present well service pump systems for
delivering working fluid at high pressure to a well. As shown,
system 10 can be coupled to and carried by a vehicle 14 (e.g., a
truck trailer) for transportation to and from work sites. In some
embodiments, a system (e.g., 10) can be coupled to a skid frame
that can then be loaded and offloaded from a vehicle (e.g.,
14).
[0035] As shown, system 10 includes a motor 18, which is configured
to drive a plurality of hydraulic pumps 22 (FIG. 3) to direct fluid
as described in further detail below. Motor 18 can include one or
more sources of mechanical energy, such as a diesel engine,
gasoline engine, and/or an electric motor. In this embodiment,
system 10 includes a pump drive 26, which is coupled to motor 18
(via driveline 30) and each pump 22. Pump drive 26 is configured to
transfer mechanical energy from motor 18 to each pump 22 one at a
time or two or more at a time. As shown, each pump 22 is mounted
directly onto pump drive 26.
[0036] System 10 includes a plurality of working pump assemblies
34, each of which are coupled to and actuatable by a respective
pump 22 to deliver working fluid at a high pressure to a well. As
shown, system 10 can include any suitable number of working pump
assemblies 34, such as two, three, four, five, six, seven, eight,
nine, or ten assemblies. As shown, each assembly 34 can be mounted
on a transport vehicle (e.g., 14) by one or more
vibration-dampening mounts 38.
[0037] Referring additionally to FIGS. 5-7, one embodiment of the
present working pump assemblies 34 is shown. As shown, assembly 34
includes a hydraulic ram cylinder 42 and a working fluid end
cylinder 46. Working fluid end cylinder 46 includes a plunger rod
50 disposed within a chamber 54 defined by the fluid end cylinder.
Plunger rod 50 is configured to reciprocate within chamber 54 to
draw in working fluid into fluid end cylinder 46 via an inlet 58
and expel working fluid under high pressure to the well via an
outlet 62. As shown in FIG. 7, hydraulic ram cylinder 42 has a ram
piston rod 66 disposed within a chamber 70 defined by the ram
cylinder. Ram piston rod 66 is coupled to plunger rod 50 to actuate
the plunger rod and supply the working fluid under pressure. For
example, assembly 34 includes a coupling member 74, such as a
bracket, coupled between piston rod 66 and plunger rod 50 such that
linear and/or rotational movement of the piston rod causes a
matching linear and/or rotational movement of the plunger rod.
Further, coupling member 74 is configured to connect piston rod 66
and plunger rod 50 such that the rods are axially aligned relative
to one another.
[0038] Plunger rod 50 has an outer diameter that is smaller than an
inner diameter of a cylindrical inner sidewall 78 of working fluid
end cylinder 46. As such, plunger rod 50 is received in
spaced-apart fashion from sidewall 78 so that abrasive fluids may
be pumped without undue wear on the plunger rod and/or sidewalls.
For example, an annular space between an outer surface of plunger
rod 50 and inner sidewall 78 of working fluid end cylinder 46 is
larger than the largest expected transverse dimension of any
particle in the working fluid to prevent any single particle in the
working fluid from simultaneously contacting the outer surface of
the plunger and the inner sidewall of the working fluid end
cylinder.
[0039] In the embodiment shown, plunger rod 50 is sealed within
fluid end cylinder 46 by an end seal 82 that provides a tight seal
around an outer surface of the plunger rod and assists with
maintaining alignment of the plunger rod relative to the fluid end
cylinder. For example, end seal 82 comprises a hydraulic seal that
can be pressurized via a port extending through fluid end cylinder
46. Plunger rod 50 can have a length (measured from end seal 82 to
a distal end of the plunger rod within chamber 54 of fluid end
cylinder 46) that exceeds 12 inches (e.g., exceeds 40 inches and/or
is between 50 inches and 60 inches, such as 48 inches). The maximum
length of plunger rod 50 that extends into chamber 54 of fluid end
cylinder 46 is termed a stroke length of the plunger rod.
[0040] Hydraulic ram cylinder 42 includes a ram piston 86 (FIG. 7)
coupled to ram piston rod 66 and disposed within hydraulic ram
cylinder 42. Contrary to plunger rod 50, ram piston 86 includes an
outer diameter that fits closely and in a substantially sealed
relationship with a cylindrical inner sidewall 90 of hydraulic ram
cylinder 42. Ram piston 86 is configured to be actuatable to
reciprocate within ram cylinder 42 such that the piston, via its
connection to piston rod 66, can cause plunger rod 50 to move
accordingly within fluid end cylinder 46. For example, ram cylinder
42 comprises a first hydraulic port 94 on a first side of ram
piston 86 and a second hydraulic port 98 on a second side of the
piston. Each hydraulic port 94, 98 is configured to receive
hydraulic fluid from a respective pump 22 to actuate ram piston 86
such that the piston (via piston rod 66 and coupling member 74)
move plunger rod 50 in a first direction 102 to expel working fluid
from fluid end cylinder 46 during a forward stroke of the plunger
rod and in a second direction 106 to draw working fluid into the
fluid end cylinder during a return stroke of the plunger rod. For
example, in the depicted embodiment, when plunger rod 50 is in the
forward stroke, the plunger rod occupies a majority of the volume
of chamber 54, thereby reducing the volume available for working
fluid within the chamber and thus forcing the working fluid out of
fluid end cylinder 46 via outlet 62.
[0041] Ram piston 86 has a piston surface area 110 upon which
hydraulic fluid in chamber 70 can act to move the ram piston, and
thus piston rod 66, in first direction 102 and plunger rod 50 has a
piston surface area 114 upon which working fluid in chamber 54 can
act to move the plunger rod in second direction 106. In this
embodiment, piston surface area 110 of at least one ram piston 86
is greater than, such as approximately two or more times greater
than, piston surface area of plunger rod 50.
[0042] Each pump 22 is configured to be driven by motor 18 to
supply a hydraulic fluid under high pressure to first hydraulic
port 94 and second hydraulic port 98 of a respective ram cylinder
42. As shown in FIG. 8, each pump 22 can be fluidly coupled to a
respective working fluid pump assembly 34 using a closed-loop
hydraulic circuit 118. Further, each pump 22 can operate
bi-directionally to actuate ram piston 86 in both first direction
102 and second direction 106. For example, each pump 22 is coupled
to a respective ram cylinder 42 such that the pump is in fluid
communication with each of first hydraulic port 94 and second
hydraulic port 98 of the ram cylinder to pump hydraulic fluid from
the second hydraulic port directly into the first hydraulic port to
actuate ram piston 86 to drive plunger rod 50 in first direction
102 (forward stroke) and from the first hydraulic port directly
into the second hydraulic port to actuate the ram piston to drive
the plunger rod in second direction 106 (return stroke). By using a
closed-loop hydraulic circuit 118 to actuate ram piston 86, and
thereby actuate plunger rod 50, less hydraulic fluid is required
for actuating assembly 34, as compared to a system (e.g., 10)
having an open-loop hydraulic circuit.
[0043] At least one pump 22 can comprise a fixed-displacement
hydraulic pump. In some embodiments, at least one pump (e.g., 22)
can comprise a variable-displacement hydraulic pump. Each pump 22
direct fluid to ports 94, 98 at a variable flow rate.
[0044] In some embodiments, system 10 may include a hydraulic fluid
reservoir 122 configured to be in fluid communication with each
pump 22 to compensate for leakage and/or other operational losses
of hydraulic fluid in the system.
[0045] As shown, system 10 includes a working fluid end block 126
that comprises, for each assembly 34, an inlet 58 having an inlet
check valve 130 fluidly coupled to chamber 54 of fluid end cylinder
46 and configured to permit working fluid to be drawn into the
fluid end cylinder but prevent working fluid from exiting the fluid
end cylinder through the inlet check valve. In this embodiment, for
at least one assembly 34, working fluid directed to inlet 58 can
flow from an elevated tank and/or through a pump, such that the
working fluid is pressured when it enters chamber 54 of fluid end
cylinder 46 through inlet valve 130, thereby urging plunger rod 50
in its return stroke. In operation, inlet check valve 130 prevents
working fluid from exiting chamber 54 through inlet 58, thereby
enabling working fluid to be pressurized in chamber 54 of fluid end
cylinder 46 during the forward stroke of plunger rod 50.
[0046] In this embodiment, end block 126 comprises, for each
assembly 34, outlet 62 having an outlet check valve 218 fluidly
coupled to chamber 54 of fluid end cylinder 46 and configured to
permit working fluid to exit the fluid end cylinder while
preventing working fluid from being drawn into the fluid end
cylinder through the outlet check valve. In operation, outlet check
valve 134 prevents working fluid that is pressurized downstream of
the outlet check valve from entering chamber 54 of fluid end
cylinder 46 during the return stroke of plunger rod 50 of assembly
34 and during the forward stroke of a plunger rod (e.g., 50) of one
or more of the other working fluid pump assemblies (e.g., 34) of
system 10.
[0047] As shown, system 10 comprises a suction manifold 138 fluidly
coupled to each inlet check valve 130 of end block 126 to
distribute working fluid to each of the inlet check valves in
parallel. System 10 comprises a discharge manifold 142 coupled to
each outlet check valve 134 of end block 126 to collect working
fluid from each of the outlet check valves in parallel.
[0048] System 10 comprises a control system 146 having at least one
processor 150, one or more of which is configured to control the
operation of each pump 22. Control system 146, and thus
processor(s) 150 can be electronically coupled to each pump 22 via
wired or wireless connection. Processor(s) 150 can be configured to
control a flowrate and/or direction of hydraulic fluid flowing
between each pump and its respective ram cylinder 42. For example,
processor(s) 150 can be configured to control each pump 22 such
that it directs hydraulic fluid, at any suitable flowrate, in a
first direction from second hydraulic port 98 to first hydraulic
port 94 and a second direction from the first hydraulic port to the
second hydraulic port. Processor(s) 150 can be configured to
control the frequency and sequence at which each pump 22 alternates
the direction hydraulic fluid between the first and second
directions such that system 10, via collective operation of the
pumps, delivers a continuous and pulseless output flow of working
fluid from fluid end cylinders 46 to the well, as described in
paragraphs [0067]-[0069] and FIG. 16 of U.S. Publication
2015/0192117, which is hereby incorporated by reference in its
entirety.
[0049] In this embodiment, the length and rate at which each ram
piston 86 completes its forward and return strokes can be adjusted
by one or more parameters of system 10. For example, with the aid
of one or more sensors 154 configured to collect data indicative of
ram piston 86 relative to ram cylinder 42, the length and rate of
the forward and return strokes of each ramp piston can be adjusted
by control system 146, which can vary the pressure and/or the rate
at which hydraulic fluid is delivered to and removed from each ram
cylinder 42. For example, assuming that hydraulic fluid is
delivered at a pressure that is sufficient to move ram piston 86,
the faster the hydraulic fluid is delivered to first hydraulic port
94 and/or removed from chamber 70 via second hydraulic port 98 by
pump 22, the faster the ram piston will complete its forward
stroke. Conversely, if it is more advantageous for the return
stroke to be completed faster (have a shorter duration) than the
forward stroke, pump 22 can be controlled to more quickly deliver
hydraulic fluid to second hydraulic port 98 and/or remove hydraulic
fluid from chamber 70 via first hydraulic port 94.
[0050] The length and rate of the forward and return strokes of
each ramp piston 86 can be adjusted to increase pump efficiency
and/or reduce cyclic fatigue. For example, to increase pump
efficiency, ram cylinder 42 and/or fluid end cylinder 46 can be
elongated to permit ram piston 86 and/or plunger rod 50 additional
travel within respective chambers 70, 54, thereby allowing for more
working fluid to be drawn into fluid end cylinder's chamber and for
more working fluid to be expelled from the fluid end chamber into
the well for every stroke, as compared to shorter ram cylinders
and/or fluid end cylinders. Further, the longer stroke length can
significantly reduce the number of strokes required to pump a given
volume, and thereby reduce the rate at which plunger rod 50 must
cycle, reducing fatigue and extending fluid end life. For further
example, the return and forward stroke of each ram piston 86 can be
controlled (e.g., by control system 146) to prevent contact between
the ram piston and opposing interior end walls 158 of ram cylinder
42. That is, when ram piston 86 reciprocates within ram cylinder 42
during and between the forward and return strokes, the ram piston
is, at all times, spaced a distance from a first interior end wall
158 of the ram cylinder and a second interior end wall 158 of the
ram cylinder opposite the first end wall.
[0051] Some embodiments of the present methods include delivering a
working fluid to a well with a well service pump system (e.g., 10)
comprising: at least two working fluid pump assemblies (e.g., 34),
each comprising: a working fluid end cylinder (e.g., 46) having a
plunger rod (e.g., 50) configured to reciprocate within the fluid
end cylinder; and a hydraulic ram cylinder (e.g., 42) having a ram
piston (e.g., 86) configured to reciprocate within the hydraulic
ram cylinder and a piston rod (e.g., 66) coupled to the ram piston
and coupled to the plunger rod of the working fluid end cylinder;
wherein the hydraulic ram cylinder includes a first hydraulic port
(e.g., 94) on a first side of the ram piston and a second hydraulic
port (e.g., 98) on a second side of the ram piston; a plurality of
bi-directional pumps (e.g., 22), each fluidly coupled to a
respective one of the working fluid pump assemblies (e.g., 34);
wherein delivering the working fluid comprises: actuating the ram
piston of the hydraulic ram cylinder to move the plunger rod of the
working fluid end cylinder: in a first direction (e.g., 102) to
expel working fluid from the fluid end cylinder during a forward
stroke of the plunger rod, and in a second direction (e.g., 106) to
draw working fluid into the fluid end cylinder during a return
stroke of the plunger rod; and directing hydraulic fluid, via the
bi-directional pump: from the second hydraulic port directly into
the first hydraulic port to actuate the ram piston to drive the
plunger rod in the first direction; and from the first hydraulic
port directly into the second hydraulic port to actuate the ram
piston to drive the plunger rod in the second direction. Some
embodiments of the present methods additionally include actuating a
motor (e.g., 18) to drive each of the bi-directional pumps to
direct fluid to the first and second ports. In some embodiments of
the present methods, the motor comprises an electric motor and/or a
combustion engine. In some embodiments of the present methods, at
least one of the hydraulic pumps comprises a fixed-displacement
hydraulic pump.
[0052] The above specification and examples provide a complete
description of the structure and use of illustrative embodiments.
Although certain embodiments have been described above with a
certain degree of particularity, or with reference to one or more
individual embodiments, those skilled in the art could make
numerous alterations to the disclosed embodiments without departing
from the scope of this invention. As such, the various illustrative
embodiments of the methods and systems are not intended to be
limited to the particular forms disclosed. Rather, they include all
modifications and alternatives falling within the scope of the
claims, and embodiments other than the one shown may include some
or all of the features of the depicted embodiment. For example,
elements may be omitted or combined as a unitary structure, and/or
connections may be substituted. Further, where appropriate, aspects
of any of the examples described above may be combined with aspects
of any of the other examples described to form further examples
having comparable or different properties and/or functions, and
addressing the same or different problems. Similarly, it will be
understood that the benefits and advantages described above may
relate to one embodiment or may relate to several embodiments. For
example, embodiments of the present methods and systems may be
practiced and/or implemented using different structural
configurations, materials, ionically conductive media, monitoring
methods, and/or control methods.
[0053] The claims are not intended to include, and should not be
interpreted to include, means-plus- or step-plus-function
limitations, unless such a limitation is explicitly recited in a
given claim using the phrase(s) "means for" or "step for,"
respectively
* * * * *