Note: Descriptions are shown in the official language in which they were submitted.
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SYSTEMS AND METHODS OF OPTIMIZED PUMP SPEED CONTROL TO REDUCE
CAVITATION, PULSATION AND LOAD FLUCTUATION
TECHNICAL FIELD
The present disclosure generally relates to subterranean drilling operations,
more
particularly, to systems and methods of controlling pump speed to reduce
cavitation and load
fluctuation in the pumped fluids.
BACKGROUND
Hydrocarbons, such as oil and gas, are commonly obtained from subterranean
formations that may be located onshore or offshore. The development of
subterranean operations
and the processes involved in removing hydrocarbons from a subterranean
formation are
complex. Typically, subterranean operations involve a number of different
steps such as, for
example, mixing and pumping fluids into a wellbore at a desired well site.
Cavitation, pulsation, and load fluctuation are common problems/faults
encountered
when pumping fluids. In particular, cavitation can cause accelerated wear and
mechanical
damage to pump components, couplings, gear trains, and drive motors.
Cavitation and load
fluctuation are often caused by the pulsation of the pumping apparatus.
Cavitation is the
formation of vapor bubbles in the inlet or the suction zone/stroke of the
pump. This condition
occurs when local pressure drops to below the vapor pressure of the liquid
being pumped. These
vapor bubbles collapse or implode when they enter a high pressure zone (for
example, at the
discharge valve during the discharge/power stroke) of the pump causing erosion
of or damage to
pump components or both. If a pump runs for an extended period under
cavitation conditions,
permanent damage may occur to the pump structure and accelerated wear and
deterioration of
pump internal surfaces and seals may occur. Depending on the type of pump,
other problems
may occur such as inlet or outlet blockage, leakage of air into the system due
to faulty pump
seals or valves, leaky or damaged valves, internal parts impacting the pump
casing, etc.
Consequently, a need exists for improved systems and methods for preventing
cavitation,
pulsation, and load fluctuation in pumps.
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BRIEF DESCRIPTION OF THE DRAWINGS
For a more complete understanding of the present disclosure and its features
and
advantages, reference is now made to the following description, taken in
conjunction with the
accompanying drawing, in which:
FIG. 1 is a schematic view of the pumping apparatus in accordance with certain
embodiments of the present disclosure.
FIG 2. is a schematic view of an exemplary fracturing apparatus in accordance
with
certain embodiments of the present disclosure.
While embodiments of this disclosure have been depicted, such embodiments do
not
imply a limitation on the disclosure, and no such limitation should be
inferred. The subject
matter disclosed is capable of considerable modification, alteration, and
equivalents in form and
function, as will occur to those skilled in the pertinent art and having the
benefit of this
disclosure. The depicted and described embodiments of this disclosure are
examples only, and
not exhaustive of the scope of the disclosure.
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DETAILED DESCRIPTION
Illustrative embodiments of the present disclosure are described in detail
herein. In the
interest of clarity, not all features of an actual implementation are
described in this specification.
It will of course be appreciated that in the development of any such actual
embodiment,
numerous implementation specific decisions must be made to achieve developers'
specific goals,
such as compliance with system related and business related constraints, which
will vary from
one implementation to another. Moreover, it will be appreciated that such a
development effort
might be complex and time consuming, but would nevertheless be a routine
undertaking for
those of ordinary skill in the art having the benefit of the present
disclosure. Furthermore, in no
way should the following examples be read to limit, or define, the scope of
the disclosure.
The present disclosure relates to systems and methods for pumping fluids, more
particularly, to systems and method of controlling pump speed to reduce
cavitation and load
fluctuation in the pumped fluids.
Cavitation is often caused by the improperly configured rig-up jobs. A rig-up
job may
be considered improperly configured for any number of reasons. For example, a
rig-up job is
improperly configured when the hoses that connect the blender to the pumps and
the hoses that
lead downhole from the pumps vary in length, number, or diameter. Cavitation
caused by an
improperly configured rig-up job is exacerbated by high pump speeds, which are
often
associated with well stimulation treatments and other downhole operations.
Well stimulation
treatments, such as fracturing or acidizing treatments, require high pump
speeds in order to
generate the requisite pressure to fracture or stimulate a subterranean
formation. Furthermore,
the pumping of slurries in other subterranean operations requires relatively
high pump speeds to
ensure the particulates remain suspended.
Cavitation can be reduced by fluctuating the speed of the pump in a periodic
manner
such that the pump speed effectively prevents vapor bubbles in the pump's
inlet from forming.
A reduction in cavitation may be achieved by varying the speed of the engine
or motor that
actuates the pump. In one or more embodiments, the engine or motor may be a
diesel or other
combustion engine, an electric motor, or any combination thereof. In one or
more embodiments,
an electric motor is used as more control over the variations in speed may be
achieved. The
engine or motor may be controlled by a controller, such as, an information
handling system.
The present disclosure may be understood with reference to FIG. 1, where like
numbers
are used to indicate like and corresponding parts. FIG. 1 is a schematic view
of the pumping
apparatus 100 in accordance with certain embodiments of the present
disclosure. Pumping
apparatus 100 may be located at a well surface, at a well site along with
various types of drilling
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or fracturing equipment (not expressly shown) or at any other location where
an operation
requires a pumping apparatus 100.
The pumping apparatus 100 comprises a pump 10 coupled to a primary mover 14 by
a
drive train 12. In certain embodiments, the pump 10 comprises a positive
displacement pump.
In certain embodiments, the primary mover 14 comprises a drive mechanism 40.
Drive
mechanism 40 may comprise an internal combustion engine. In certain
embodiments, the
internal combustion engine may comprise a diesel engine. In certain
embodiments, the drive
mechanism 40 may comprise an electric motor. In certain embodiments the
movement of the
primary mover 14 actuates the movement of the pump 10. In certain embodiments,
the primary
mover 14 is coupled directly to the pump 10 and actuates pumping of pump 10
directly. In
certain embodiments, the primary mover 14 is coupled to the drive train 12 and
actuates the
pumping of pump 10 by actuating the movement of the drive train 12. In certain
embodiments,
the speed of the primary mover 14 determines the pumping speed of the pump 10.
A person of
skill in the art with the benefit of this disclosure would see that the speed
at which the primary
mover 14 operates may determine the rotational speed of pump 10. Furthermore,
a person of
skill in the art with the benefit of this disclosure would appreciate that the
primary mover 14 may
be controlled to change the rotational speed of the pump 10 in any manner
known in the art.
The pump 10 operates so as to pump fluid from an upstream portion of a fluid
channel
28 to a downstream portion of a fluid channel 18. The fluid channels 18 and 28
may comprise
hosing, piping, any kind of hosing or piping known in the art or any
combination thereof. In one
or more embodiments, fluid channel 18 is downstream of a blender (not shown).
In one or more
embodiments, fluid channel 18 leads directly into the wellbore 60 as described
in Figure 2. In
one or more embodiments, fluid channel 18 couples to a manifold (not shown).
The pumping apparatus 100 further comprises a controller 16. The controller 16
is
electronically coupled to the primary mover 14. The controller 16 may comprise
a processor 30
and a memory 32 where the memory 32 comprises one or more instructions, such
as a program,
that when executed by the processor 30 control the primary mover 14. In one or
more
embodiments, the primary mover 14 may comprise a memory 34 and a receiver 36
such that the
primary mover 14 may receive the one or more commands sent by the controller
16. The
controller 16 may throttle the speed at which the primary mover 14 operates.
Throttling the
speed of the primary mover 14 may cause the speed of the primary mover 14 and
thus the pump
10 the primary mover 14 actuates to cyclically decrease and increase
continuously.
Additionally, the controller 16 may be programmed to optimize one or more
characteristics of the pumping apparatus 100. For example, for a given
operation or
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environment, one or more characteristics of the pumping apparatus 100 may be
selected for
optimization. In one or more embodiments, the controller 16 may calculate the
speed at which
the primary mover 14 operates such that the selected characteristic is
optimized. Characteristics
of the pumping apparatus 100 may include, but are not limited to, vibration of
a component of
the primary mover 14, torque or force of at least one component of the primary
mover 14, linear
.. or angular displacement of at least one component of the primary mover 14,
linear or angular
velocity of at least one component of the primary mover 14õ linear or angular
acceleration of at
least one component of the primary mover 14, fuel or electrical power
efficiency of the primary
mover 14, emissions produced by the primary mover 14, vibration of the
drivetrain 12, torque of
the drive train 12, angular velocity of the drivetrain 12, angular
acceleration of the drive train 12,
flow rate of the pump 10, inlet pressure of the pump 10, outlet pressure of
the pump 10, vibration
of the pump 10, force of the pump 10, torque of the pump 10, in linear or
angular displacement
of the pump 10, linear or angular velocity of the pump 10, linear or angular
acceleration of the
pump 10, or any other characteristic. In some embodiments, the calculated
speed is based, at
least in part, on one or more characteristics of the pumping apparatus 100.
For example, in one
.. or more embodiments, the pump 10 may accelerate fluid according to a well-
known function or
functions such as slider-crank motion equations, fluid compression and bulk
modulus relations,
valve force-mass acceleration equations. The controller 16 may be programmed
to control the
primary mover 14 based on the well-known function to optimize the flow rate of
the fluid
through the pump 10. In one or more embodiments, this calculation is based, at
least in part, on
the signals from one or more sensors discussed in greater detail below.
The pumping apparatus 100 may further comprise one or more sensors 26. Any of
the
one or more sensors 26 may be coupled to the controller 16. In one or more
embodiments, one or
more sensors 26 may be disposed within or coupled to the primary mover 14. The
sensor 26 is
coupled to the primary mover 14 such that the sensor 26 may monitor at least
one characteristic
of the primary mover 14. For example, in one or more embodiments the sensor 26
may monitor
at least one of the vibration of a component of the primary mover 14, the
torque or force of at
least one component of the primary mover 14, the linear displacement of at
least one component
of the primary mover 14, the linear or angular velocity of at least one
component of the primary
mover 14, the linear or angular acceleration of at least one component of the
primary mover 14,
or any combination thereof. In one or more embodiments, sensor 26 may comprise
a pressure
sensor, a strain gauge, an accelerometer, a position sensor, a velocity
sensor, an acoustic sensor,
or any combination thereof.
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In one or more embodiments, the sensor 26 may further communicate or transmit
the
information about the monitored characteristic to the controller 16 at regular
intervals, timed
intervals, intermittent intervals, predetermined intervals or at any other
interval. In some
embodiments, the information is communicated continuously. The controller 16
may modify the
control signal sent to the primary mover 14 based, at least in part, on the
information received
from sensor 26, such that the primary mover 14 operates to optimize any one or
more
characteristics of the pumping apparatus 100. In one or more embodiments, the
sensor 26
monitors any one or more characteristics being optimized by the controller 16.
In one or more embodiments, the pumping apparatus 100 may comprise a sensor 22
wherein the sensor 22 is coupled to the controller 16 and the drive train 12.
The sensor 22 is
coupled to the drive train 12 to monitor at least one characteristic of the
drive train 12. For
example, the sensor 22 may monitor at least one of the vibration of a
component of the drive
train 12, the torque or force of at least one component of the drive train 12,
the linear
displacement of at least one component of the drive train 12, the linear or
angular velocity of at
least one component of a drive train 12, the linear or angular acceleration of
at least one
component of the drive train 12, or any combination thereof. In one or more
embodiments,
sensor 22 may comprise a pressure sensor, a strain gauge, an accelerometer, a
position sensor, a
velocity sensor, an acoustic sensor, or any combination thereof
In one or more embodiments, the sensor 22 may further communicate the
information
about the characteristic to the controller 16 at regular intervals, timed
intervals, intermittent
intervals, predetermined intervals or at any other interval. In one or more
embodiments, the
information is communicated continuously. The controller 16 may modify the
control signal the
control 16 sends to the primary mover 14 based on the information received
from sensor 22, such
that the primary mover 14 operates to optimize a characteristic of the pumping
apparatus 100. In
some embodiments, the characteristic sensor 22 monitors the same
characteristic or a different
.. characteristic being optimized by the controller 16.
In some embodiments, the pumping apparatus 100 may comprise a sensor 24
wherein
the sensor 24 is coupled to the controller 16 and the pump 10. The sensor 24
is coupled to the
pump 10 such that it may monitor at least one characteristic of the pump 10.
For example, the
sensor 24 may monitor at least one of the vibration of a component of the pump
10, the torque or
.. force of at least one component of the pump 10, the linear displacement of
at least one
component of the pump 10, the linear or angular velocity of at least one
component of a pump
10, the linear or angular acceleration of at least one component of the pump
10, fluid flow,
pressure, or any combination thereof In some embodiments, sensor 24 may
comprise a strain
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gauge, an accelerometer, a pressure sensor, a position sensor, a velocity
sensor, an acoustic
sensor, a flow meter, or any combination thereof.
In one or more embodiments, the sensor 24 may further communicate the
information
about the characteristic to the controller 16 at regular intervals, timed
intervals, intermittent
intervals, predetermined intervals or at any other interval. In one or more
embodiments, the
information is communicated continuously. The controller 16 may modify the
control signal the
controller 16 sends to the primary mover 14 based on the information received
from sensor 24,
such that the primary mover 14 operates to optimize a characteristic of the
pumping apparatus
100. In one or more embodiments, the characteristic sensor 24 monitors the
same characteristic
optimized or a different characteristic being by the controller 16.
In one or more embodiments, the downstream portion of a fluid 18 may comprise
a
sensor 20, wherein the sensor 20 is coupled to the controller 16. The sensor
20 monitors at least
one characteristic of the downstream portion of the fluid channel 18. One or
more characteristics
monitored by sensor 20 may comprise at least one of the vibration of the
downstream portion of
a fluid channel, fluid flow, pressure, or any combination thereof In one or
more embodiments,
sensor 20 may comprise an accelerometer, a flow meter, a pressure sensor, or
any combination
thereof.
In one or more embodiments, the sensor 20 may further communicate the
information
about the characteristic to the controller 16 at regular intervals, timed
intervals, intermittent
intervals, predetermined intervals or at any other interval. In one or more
embodiments, the
information is communicated continuously. The controller 16 may modify the
control signal the
controller 16 sends to the primary mover 14 based on the information received
from sensor 20,
such that the primary mover 14 operates to optimize a characteristic of the
pumping apparatus
100. In one or more embodiments, the characteristic sensor 20 monitors the
same characteristic
optimized by the controller 16. For example, in certain embodiments, sensor 20
may monitor
any one or more characteristics including, but not limited to, the vibration
of the downstream
portion of the fluid channel 18, while the controller 16 commands the primary
mover 14 to
operate to optimize the flow rate of the fluid in fluid channel 18. In certain
embodiments, the
sensor 20 may monitor the vibration of the downstream portion of the fluid
channel 18, while the
controller 16 commands the primary mover 14 to operate to reduce the vibration
of the pump 10.
In some embodiments, the sensor 20 monitors a different characteristic than
the characteristic
being optimized by controller 16.
In one or more embodiments, the upstream portion of a fluid channel 28 may
comprise
a sensor 21, wherein the sensor 21 is coupled to the controller 16. The sensor
21 monitors at
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least one characteristic of the upstream portion of the fluid channel 28. One
or more
characteristics monitored by sensor 21 may comprise at least one of: the
vibration of the
upstream portion of a fluid channel, fluid flow, pressure, or any combination
thereof In one or
more embodiments, sensor 21 may comprise an accelerometer, a flow meter, a
pressure sensor,
or any combination thereof.
In one or more embodiments, the sensor 21 may further communicate the
information
about the monitored characteristic to the controller 16 at regular intervals,
timed intervals,
intermittent intervals, predetermined intervals or at any other interval. In
one or more
embodiments, the information is communicated continuously. The controller 16
may modify the
control signal the controller 16 sends to the primary mover 14 based on the
information received
from sensor 21, such that the primary mover 14 operates to optimize a
characteristic of the
pumping apparatus 100. In one or more embodiments, the characteristic sensor
21 monitors the
same characteristic optimized by the controller 16. For example, in certain
embodiments, the
characteristic sensor 21 may monitor the vibration of the upstream portion of
the fluid channel
28, while the controller 16 commands the primary mover 14 to operate to
optimize the flow rate
of the fluid in fluid channel 28. In certain embodiments, the sensor 21 may
monitor the vibration
of the upstream portion of the fluid channel 28, while the controller 16
commands the primary
mover 14 to operate to reduce the vibration of the pump 10. In some
embodiments, the sensor
21 monitors a different characteristic than the characteristic being optimized
by controller 16.
Figure 2 shows the well 60 during an exemplary fracturing operation using the
pumping apparatus 100 in a portion of a subterranean formation of interest 102
surrounding
a well bore 104. Apart from fracturing operations, the apparatus of Figure 2
may be used in a
variety of different well stimulation treatments such as aeidizing treatments.
The well bore
104 extends from the surface 106, and the fracturing fluid 108 is applied to a
portion of the
subterranean formation 102 surrounding the horizontal portion of the well
bore. Although
shown as vertical deviating to horizontal, the well bore 104 may include
horizontal,
vertical, slant, curved, and other types of well bore geometries and
orientations, and the
fracturing treatment may be applied to a subterranean zone surrounding any
portion of the
well bore. The well bore 104 can include a easing 110 that is cemented or
otherwise
secured to the well bore wall. The well bore 104 can be uncased or include
uncased
sections. Perforations can be formed in the casing 110 to allow fracturing
fluids and/or
other materials to flow into the subterranean formation 102. In cased wells,
perforations can
be formed using shape charges, a perforating gun, hydro-jetting and/or other
tools.
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The well is shown with a work string 112 depending from the surface 106 into
the
well bore 104. The pump and blender system 50 is coupled a work string 112 to
pump the
fracturing fluid 108 into the well bore 104. The working string 112 may
include coiled
tubing, jointed pipe, and/or other structures that allow fluid to flow into
the well bore 104.
The working string 112 can include flow control devices, bypass valves, ports,
and or
other tools or well devices that control a flow of fluid from the interior of
the working
string 112 into the subterranean zone 102. For example, the working string 112
may
include ports adjacent the well bore wall to communicate the fracturing fluid
108
directly into the subterranean formation 102, and/or the working string 112
may include
ports that are spaced apart from the well bore wall to communicate the
fracturing fluid
108 into an annulus in the well bore between the working string 112 and the
well bore
wall.
The working string 112 and/or the well bore 104 may include one or more sets
of
packers 114 that seal the annulus between the working string 112 and well bore
104 to define
an interval of the well bore 104 into which the fracturing fluid 108 will be
pumped. FIG. 2
shows two packers 114, one defining an uphole boundary of the interval and one
defining the
downhole end of the interval. When the fracturing fluid 108 is introduced into
well bore 104
(for example, in Figure 2, the area of the well bore 104 between packers 114)
at a sufficient
hydraulic pressure, one or more fractures 116 may be created in the
subterranean zone 102.
The proppant particulates in the fracturing fluid 108 may enter the fractures
116 where they
may remain after the fracturing fluid flows out of the well bore. These
proppant particulates
may "prop" fractures 116 such that fluids may flow more freely through the
fractures 116.
An embodiment of the present disclosure is a system for pumping fluid
comprising a
pump, a primary mover coupled to the pump, and a controller coupled to the
primary mover,
wherein the controller is programmed to control the primary mover so as to
optimize a first
characteristic of the system, wherein the controller commands the primary
mover to throttle its
speeds such that the primary mover's speed over time follows a cyclic or
periodic function, for
example, a sine function.
Another embodiment of the present disclosure is a method for pumping a fluid
comprising providing a pumping apparatus comprising a pump, a primary mover
that actuates
the pump, and a controller comprising a processor and a memory device
programmed to send
commands to the primary mover; and using known characteristics of the pump to
modify the
commands sent to the primary mover such that a characteristic of the pumping
apparatus is
optimized.
9
Another embodiment of the present disclosure is a method for pumping a fluid
comprising providing a pumping apparatus comprising a pump, a primary mover
mechanically
coupled to the pump by a drive train such that the primary mover actuates the
pump, a controller
that sends commands to the primary mover, and a sensor coupled to the
controller; pumping the
fluid downhole; monitoring a first characteristic of the pumping apparatus
with the sensor,
sending a signal to the controller indicative of the magnitude of the first
characteristic being
monitored by the sensor; determining an appropriate command signal to send to
the primary
mover to optimize a second characteristic of the pumping apparatus; and
sending the appropriate
command signal to the primary mover to optimize the second characteristic of
the pumping
apparatus.
Therefore, the present disclosure is well adapted to attain the ends and
advantages
mentioned as well as those that are inherent therein. The particular
embodiments disclosed above
are illustrative only, as the present disclosure may be modified and practiced
in different but
equivalent manners apparent to those skilled in the art having the benefit of
the teachings herein.
Furthermore, no limitations are intended to the details of construction or
design herein shown,
other than as described in the claims below. Also, the terms in the claims
have their plain,
ordinary meaning unless otherwise explicitly and clearly defined by the
patentee.
Date Recue/Date Received 2020-04-21
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