U.S. patent application number 16/404283 was filed with the patent office on 2020-03-26 for hydraulic fracturing equipment with non-hydraulic power.
This patent application is currently assigned to U.S. Well Services, Inc.. The applicant listed for this patent is U.S. Well Services, Inc.. Invention is credited to Brandon N. Hinderliter.
Application Number | 20200095854 16/404283 |
Document ID | / |
Family ID | 64902600 |
Filed Date | 2020-03-26 |
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United States Patent
Application |
20200095854 |
Kind Code |
A1 |
Hinderliter; Brandon N. |
March 26, 2020 |
HYDRAULIC FRACTURING EQUIPMENT WITH NON-HYDRAULIC POWER
Abstract
The present disclosure is directed to a hydraulic fracturing
system for fracturing a subterranean formation. In an embodiment,
the system can include an electric pump fluidly connected to a well
associated with the formation, and configured to pump fluid into a
wellbore associated with the well at a high pressure so that the
fluid passes from the wellbore into the formation and fractures the
formation. The system can further include one or more ancillary
units associated with the fluid pumped into the wellbore. The
system can further include a first motor electrically coupled to
the electric pump to operate the electric pump, and one or more
second motors, each of the second motors electrically coupled to
each of the ancillary units to operate the one or more ancillary
units.
Inventors: |
Hinderliter; Brandon N.;
(Houston, TX) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
U.S. Well Services, Inc. |
Houston |
TX |
US |
|
|
Assignee: |
U.S. Well Services, Inc.
Houston
TX
|
Family ID: |
64902600 |
Appl. No.: |
16/404283 |
Filed: |
May 6, 2019 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
15644487 |
Jul 7, 2017 |
10280724 |
|
|
16404283 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H02P 27/06 20130101;
H02P 27/047 20130101; F04B 49/20 20130101; F04B 51/00 20130101;
E21B 43/26 20130101; F04B 49/06 20130101; F04B 17/03 20130101; H02P
5/74 20130101 |
International
Class: |
E21B 43/26 20060101
E21B043/26; H02P 27/04 20060101 H02P027/04; F04B 17/03 20060101
F04B017/03; F04B 49/06 20060101 F04B049/06; H02P 5/74 20060101
H02P005/74; F04B 49/20 20060101 F04B049/20; F04B 51/00 20060101
F04B051/00; H02P 27/06 20060101 H02P027/06 |
Claims
1. (canceled)
2. A hydraulic fracturing system for fracturing a subterranean
formation comprising: an electric pump fluidly connected to a well
associated with the subterranean formation, and configured to pump
fluid into a wellbore associated with the well at a high pressure
so that the fluid passes from the wellbore into the subterranean
formation and fractures the subterranean formation; one or more
ancillary units associated with the fluid pumped into the wellbore;
a first motor electrically coupled to the electric pump to operate
the electric pump; one or more second motors, each of the one or
more second motors electrically coupled to at least one of the one
or more ancillary units to operate the at least one of the one or
more ancillary units.
3. The system of claim 2, wherein the first motor is selected from
the group consisting of any of an electric motor, a diesel motor, a
natural gas motor, a gasoline motor, and a hydraulic motor, or a
combination thereof.
4. The system of claim 2, further comprising: an electric
generator, wherein the first motor is electrically coupled to the
electric pump via the electric generator to generate electricity
for use by the electric pump.
5. The system of claim 2, wherein the one or more second motor
comprises an electric motor.
6. The system of claim 5, wherein the electric motor is selected
from the group consisting of any of a single-phase AC motor, a
three-phase motor, and a DC motor.
7. The system of claim 2, further comprising: a plurality of
variable-frequency drives (VFD), each VFD connected to at least on
of the first motor or the one or more second motors to control the
speed of the first motor of the one or more second motors.
8. The system of claim 7, wherein each VFD frequently performs
electric motor diagnostics to prevent damage to the first motor or
the one or more second motors.
9. The system of claim 7, further comprising: one or more trailer,
wherein the one or more ancillary units are positioned on the one
or more trailer, and wherein each VFD is positioned on the one or
more trailer proximate each of the one or more ancillary units.
10. The system of claim 9, wherein the one or more second motors
are each positioned on the one or more trailers proximate each of
the one or more ancillary units.
11. The system of claim 2, wherein additional of the one or more
ancillary units are selected from the group consisting of any of a
blender, a hydration unit, a chemical additive unit, a small pump,
a chemical pump, a water pump, a valve actuator, a cooling fan, an
auger, a mixing paddle, a conveyor belt, and a blower, or any
combination thereof.
12. The system of claim 2, wherein the one or more ancillary units
comprise a blender, the blender being positioned on a trailer and
fluidly connected to an auger or proximate a bottom elevation of
the auger, or a combination thereof, such that the one or more
second motors provide power to drive the auger.
13. The system of claim 2, wherein the one or more ancillary units
comprise the hydration unit, the hydration unit being positioned on
a trailer, the trailer further comprising a VFD, wherein the one or
more second motors are positioned any of between the hydration unit
and the VFD, or below the VFD, or a combination thereof, and
wherein the one or more second motors provide power to the
hydration unit via the VFD.
14. A hydraulic fracturing system for fracturing a subterranean
formation comprising: an electric pump fluidly connected to a well
associated with the subterranean formation, and configured to pump
fluid into a wellbore associated with the well at a high pressure
so that the fluid passes from the wellbore into the subterranean
formation and fractures the subterranean formation; one or more
ancillary units associated with the fluid pumped into the wellbore;
a first motor electrically coupled to the electric pump to operate
the electric pump; one or more second motors, the one or more
second motors comprising an electric motor, and each of the one or
more second motors electrically coupled to at least one of the one
or more ancillary units to operate the at least one of the one or
more ancillary units; and a plurality of variable-frequency drives
(VFD), each VFD connected to at least one of the first motor or the
one or more second motors to control the speed of the first motor
or the one or more second motors.
15. The system of claim 14, wherein the first motor is selected
from the group consisting of any of an electric motor, a diesel
motor, a natural gas motor, a gasoline motor, and a hydraulic
motor, or a combination thereof.
16. The system of claim 14, wherein the electric motor is selected
from the group consisting of any of a single-phase AC motor, a
three-phase motor, and a DC motor.
17. The system of claim 14, wherein each VFD frequently performs
electric motor diagnostics to prevent damage to the first motor or
the one or more second motors.
18. The system of claim 14, further comprising: one or more
trailer, wherein the one or more ancillary units are positioned on
the one or more trailer, and wherein each VFD is positioned on the
one or more trailer proximate each of the one or more ancillary
units.
19. The system of claim 14, wherein the one or more second motors
are each positioned on the one or more trailers proximate each of
the one or more ancillary units.
20. The system of claim 14, wherein additional of the one or more
ancillary units are selected from the group consisting of any of a
blender, a hydration unit, a chemical additive unit, a small pump,
a chemical pump, a water pump, a valve actuator, a cooling fan, an
auger, a mixing paddle, a conveyor belt, and a blower, or any
combination thereof.
21. A method for powering one or more ancillary units associated
with a hydraulic fracturing system, the method comprising: fluidly
connecting an electric pump to a well associated with a
subterranean formation, the electric pump configured to pump fluid
into a wellbore associated with the well at a high pressure so that
the fluid passes from the wellbore into the subterranean formation
and fractures the subterranean formation; fluidly connecting the
one or more ancillary units with the fluid pumped into the
wellbore; electrically coupling a first motor to the electric pump
to operate the electric pump; electrically coupling one or more
second motors to each of the one or more ancillary units to operate
the one or more ancillary units, the one or more second motors
comprising an electric motor; and connecting each of a plurality of
variable-frequency drives (VFD) to at least one of the first motor
or the one or more second motors to control the speed of the first
motor or the one or more second motors.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 15/644,487, filed Jul. 7, 2017, which is now
U.S. Pat. No. 10,280,724 issued May 7, 2019, the full disclosure of
which is hereby incorporated by reference herein for all
purposes.
BACKGROUND
1. Technical Field
[0002] This disclosure relates generally to hydraulic fracturing
and more particularly to systems and methods for ancillary
components of hydraulic fracturing equipment powered by non-
hydraulic electric motors.
2. Background
[0003] With advancements in technology over the past few decades,
the ability to reach unconventional sources of hydrocarbons has
tremendously increased. Horizontal drilling and hydraulic
fracturing are two such ways that new developments in technology
have led to hydrocarbon production from previously unreachable
shale formations. Hydraulic fracturing operations typically require
powering numerous components in order to recover oil and gas
resources from the ground. For example, hydraulic fracturing
usually includes pumps that inject fracturing fluid down the
wellbore, blenders that mix proppant into the fluid, cranes,
wireline units, and many other components that all must perform
different functions to carry out fracturing operations.
[0004] Historically, large diesel motors have been used for drive
power in hydraulic fracturing systems, while a system of hydraulics
is typically used to drive smaller ancillary devices such as
augers, chemical pumps, mixing paddles, water pumps, and cooling
fans. For example, hydraulic power can include use of pressure and
flow of hydraulic oil as a power source for turning valves,
rotating fans and blowers, or spinning pumps to displace fracturing
slurry, proppant, or chemicals onboard individual pieces of
ancillary equipment. The use of hydraulics to power such ancillary
elements of the hydraulic fracturing system includes several
disadvantages, however.
[0005] For example, a fundamental drawback of using hydraulics to
operate a chemical pump is the irregularity of the control system.
Typically a proportional valve is used to regulate the flow of
hydraulic fluid from a hydraulic pump to a hydraulic motor used to
drive a chemical pump. Combined with a
proportional-integral-derivative (PID) loop control system, a
chemical pump with a hydraulic motor can be controlled accurately
within a given range of fluid rate. However, the upper rate (pump
speed) can be influenced by the charge pressure of the hydraulic
system, which can fluctuate based on how heavily the entire
hydraulic system is being used or by the level of power of the
drive motor powering the hydraulic pumps for the charge pressure.
Every time a new chemical pump or auger is turned on, the charge
pressure will at least temporarily drop, which can cause an
undesirable fluctuation in the speed of operation of each chemical
pump.
[0006] Another common problem with using hydraulic motors to power
chemical pumps may occur when an operator attempts to run a
chemical pump too slowly. For example, a normal progressive cavity
chemical pump rated for a maximum of 15 gallons per minute (gpm)
will not operate smoothly below 2 gpm due to the inability of the
PID controller and proportional valve to properly regulate the flow
of hydraulic fluid at such a low setting. This lower operability
limit can cause the pump to surge on and off, resulting in the
addition of an incorrect amount of chemicals to the fracturing
slurry. In many instances, this problem is dealt with by installing
multiple chemical pumps of different sizes (max fluid rates), such
that different chemicals can be run accurately at different speeds
(fluid rates). The myriad of different chemical pumps must be
preplanned and installed before commencing hydraulic fracturing
operations, often based on customer requirements, or alternatively
several extra chemical pumps must be installed at all times to
allow for the flexibility required during fracturing operations,
either of which results in inefficiencies in operation and
cost.
[0007] Reliability can also be a problem with hydraulic circuits. A
single failure in a hydraulic hose or hydraulic pump can cause
every hydraulic motor attached to that circuit to fail. Hydraulic
systems also have filters which can clog or leak, dry rotted hoses
that can fail, fittings that can leak or fail, pumps that can
overheat, and fluid that can thicken and "gel up" in the winter,
which requires heaters to be installed in the hydraulic fluid
reservoir. Moreover, hot, pressurized hydraulic fluid has been
known to injure workers, is contaminating to the environment, and
is heavy, thereby adding to the weight of the mobile trailer on
which the ancillary equipment is situated at a hydraulic fracturing
site. Hydraulic fluid also requires dedicated radiators, which
represent another point of possible failure and which take up
valuable space at the hydraulic fracturing operation drill pad and
add noise pollution.
[0008] Thus, it may be desirable to modify hydraulic fracturing
systems to power ancillary units, such as blenders and chemical
pumps, with a non-hydraulic power source.
SUMMARY
[0009] With the creation of the electrical microgrid for electrical
hydraulic fracturing equipment, electric motors can now easily be
used anywhere mechanical rotation is required. Previously, large
diesel motors were used for drive power in hydraulic fracturing
systems, while a system of hydraulics were used to power smaller
ancillary devices such as augers, chemical pumps, mixing paddles,
water pumps, and cooling fans.
[0010] The present disclosure is directed to a system and method
for powering ancillary units associated with a hydraulic fracturing
system, such as blenders and pumps, with a non-hydraulic power
source. In particular, the present disclosure is directed to use of
a plurality of electric motors to operate each ancillary unit in a
hydraulic fracturing system.
[0011] In accordance with an aspect of the disclosed subject
matter, the method and system of the present disclosure provide a
hydraulic fracturing system for fracturing a subterranean
formation. In an embodiment, the system can include an electric
pump fluidly connected to a well associated with the subterranean
formation and configured to pump fluid into a wellbore associated
with the well at a high pressure so that the fluid passes from the
wellbore into the subterranean formation and fractures the
subterranean formation; one or more ancillary units associated with
the fluid pumped into the wellbore; a first motor electrically
coupled to the electric pump to operate the electric pump; and one
or more second motors, each of the one or more second motors
electrically coupled to at least one of the one or more ancillary
units to operate the at least one of the one or more ancillary
units.
[0012] In an embodiment, the first motor can be selected from the
group including any of an electric motor, a diesel motor, a natural
gas motor, a gasoline motor, and a hydraulic motor, or a
combination thereof.
[0013] In an embodiment, the system can further include an electric
generator, where the first motor can be electrically coupled to the
electric pump via the electric generator to generate electricity
for use by the electric pump.
[0014] In an embodiment, the one or more second motor can include
an electric motor.
[0015] In an embodiment, the electric motor can be selected from
the group including any of a single-phase AC motor, a three-phase
motor, and a DC motor.
[0016] In an embodiment, the hydraulic fracturing system can
further include a plurality of variable-frequency drives (VFD), and
each VFD can be connected to at least one of the first motor or the
one or more second motors to control the speed of the first motor
or the one or more second motors.
[0017] In an embodiment, each VFD can frequently perform electric
motor diagnostics to prevent damage to the first motor or the one
or more second motors.
[0018] In an embodiment, the system can further include one or more
trailer, where the one or more ancillary units can be positioned on
the one or more trailers, and where each VFD can be positioned on
the one or more trailer proximate each of the one or more ancillary
units.
[0019] In an embodiment, the one or more second motors can each be
positioned on the one or more trailers proximate each of the one or
more ancillary units.
[0020] In an embodiment, the one or more ancillary units can be
selected from the group including any of a blender, a hydration
unit, a chemical additive unit, a small pump, a chemical pump, a
water pump, a valve actuator, a cooling fan, an auger, a mixing
paddle, a conveyor belt, and a blower, or any combination
thereof.
[0021] In an embodiment, the one or more ancillary units can
include a blender, the blender being positioned on a trailer and
fluidly connected to an auger. In an embodiment, the one or more
second motors can be positioned any of proximate a top elevation of
the auger or proximate a bottom elevation of the auger, or a
combination thereof, such that the one or more second motors can
provide power to drive the auger.
[0022] In an embodiment, the one or more ancillary units can
include a hydration unit, the hydration unit being positioned on a
trailer, and the trailer further including a VFD. In an embodiment,
the one or more second motors can be positioned any of between the
hydration unit and the VFD, or below the VFD, or a combination
thereof, and the one or more second motors can provide power to the
hydration unit via the VFD.
[0023] The present disclosure is also directed to a hydraulic
fracturing system for fracturing a subterranean formation. In an
embodiment, the system can include an electric pump fluidly
connected to a well associated with the subterranean formation, and
configured to pump fluid into a wellbore associated with the well
at a high pressure so that the fluid passes from the wellbore into
the subterranean formation and fractures the subterranean
formation. In an embodiment, the system can further include one or
more ancillary units associated with the fluid pumped into the
wellbore. In an embodiment, the system can further include a first
motor electrically coupled to the electric pump to operate the
electric pump. In an embodiment, the system can further include one
or more second motors, the one or more second motors including an
electric motor, and each of the one or more second motors
electrically coupled to at least one of the one or more ancillary
units to operate the at least one of the one or more ancillary
units. In an embodiment, the system can further include a plurality
of variable-frequency drives (VFD), each VFD connected to at least
one of the first motor or the one or more second motors to control
the speed of the first motor or the one or more second motors.
[0024] The present disclosure is further directed to a method for
powering one or more ancillary units associated with a hydraulic
fracturing system. In an embodiment, the method can include fluidly
connecting an electric pump to a well associated with a
subterranean formation, the electric pump configured to pump fluid
into a wellbore associated with the well at a high pressure so that
the fluid passes from the wellbore into the subterranean formation
and fractures the subterranean formation. In an embodiment, the
method can further include fluidly connecting the one or more
ancillary units with the fluid pumped into the wellbore, and
electrically coupling a first motor to the electric pump to operate
the electric pump. In an embodiment, the method can further include
electrically coupling one or more second motors to each of the one
or more ancillary units to operate the one or more ancillary units,
the one or more second motors comprising an electric motor; and
connecting each of a plurality of variable-frequency drives (VFD)
to at least one of the first motor or the one or more second motors
to control the speed of the first motor or the one or more second
motors.
[0025] The use of electric motors, rather than hydraulic pumps, to
power the ancillary units of a hydraulic fracturing system has many
advantages. For example, small electrical motors with small
variable-frequency drives (VFDs) are able to spin steadily at any
speed up to their maximum designed rotations per minute (RPM),
unlike hydraulic pumps, which may operate at irregular speeds or be
limited to higher speeds, as discussed above. The use of electric
motors can allow operators to install a single type of chemical
pump or auger motor and accurately control the pump or motor
regardless of desired rates and job designs, rather than requiring
installation of multiple pumps for operation at multiple settings,
as would be required with hydraulic motors.
[0026] Additionally, without the use of hydraulic pumps, all
hydraulic fluid can be eliminated; this has several advantages.
Preventing spills of contaminating fluids has become a very high
priority in the industry, and hydraulic oil is one of the most
commonly spilled fluids on well stimulation sites due to blown
hoses, leaking seals, changing filters, changing pumps and motors,
overfilled reservoirs, or oil transfers from buckets and totes.
Requiring spare totes of hydraulic oil and replacement hydraulic
filters, as well as spare parts for JIC fittings, hydraulic hoses,
and gauges, may no longer be necessary with the use of electric
motors. The use of electric power, rather than hydraulic power,
also promotes a "greener" image of environmental responsibility, at
least because electric motors save time and money over hydraulic
pumps, as maintenance time is greatly reduced.
[0027] Weight reduction is another advantage of using electric
motors rather than hydraulic pumps. Without the need for hydraulic
oil, the reservoir, filters and filter houses, hoses, pumps,
motors, ball valves, racks of gauges, and electronically controlled
proportional valves can all be removed from ancillary unit
trailers, and can be replaced with comparatively small and
light-weight three-phase, 600V electric motors, power cables, and
small VFDs.
[0028] The most obvious and notable change will be the elimination
of the single large electric motor (HPU), which is used to drive
the multitude of hydraulic pumps in existing hydraulic fracturing
systems that utilize hydraulic pumps to power the ancillary units.
Typical HPUs operate in "on" and "off" settings only, and the speed
is not adjustable. While this setup eliminates the need for a large
and expensive VFD, since a simple soft starter is used, the HPU is
very inefficient in power usage. Regardless of the hydraulic power
that is used, if only a single chemical pump is being used or if
all chemical pumps, boost pumps, and valves are being utilized, the
electric drive motor for the hydraulics must be on and at full
speed in order to rotate the hydraulic pumps. This constant
operation leads to decreased efficiency, and increased costs and
noise pollution.
[0029] With the HPU removed, the associated air cooling blower
often positioned on top of the HPU can also be removed, further
saving space, electrical power, the possibility of a single failure
point--where one failed part can cripple the entire system--and
reducing noise, as the blower motors are often the most prominent
source of noise in the hydraulic fracturing fleet.
[0030] With the elimination of hydraulics-based power, up to three
HPU motors and associated blower motors can be removed from each
typical fleet. The reduction in noise associated with this removal
may be most noticeable during times where the fracturing pumps,
mixing equipment, and turbine generators are in a standby or
low-load state. This accounts for approximately 50% of the time
during well stimulation activities and occurs during wireline pump
downs, injection tests, pressure tests, and at the beginning of
fracturing stages.
[0031] The elimination of the HPU motor can also allow the
auxiliary trailer to be reduced in size, or eliminated entirely, as
a result of the extra space created on the ancillary unit trailers.
Extra space is also created on the ancillary equipment, due to the
removal of the hydraulic cooling fans, HPU motor, HPU cooling
system, hydraulic pumps, hydraulic pump enclosure, hydraulic oil
reservoir, and proportional valve bank, and surrounding deck space
required for maintenance and monitoring of the hydraulic system.
Removing these hydraulic power-related units frees up the entire
tongue of the trailer on which the ancillary equipment is situated,
and several feet onto the drop portion of the trailer chassis. In
this space, it is possible to install a VFD housing similar to one
that is installed on the fracturing pump trailers. For example, the
blender VFD housing can contain a motor control center (MCC) for
control of all electrically powered chemical pumps, proppant
augers, paddles, water pumps, and blower motors for the discharge
pump's large electric motor (known as the SPU). Lighting control,
power cable connections, and the SPU VFD drive can all be housed on
the blenders and hydration units, and can be removed from the
auxiliary trailer. Placing these components on the ancillary
equipment will allow the one or two auxiliary trailers commonly
included in hydraulic fracturing operations to be drastically
reduced in size or completely eliminated altogether, thereby
reducing the overall footprint required for the well site.
[0032] Removing the hydraulic pumps can also eliminate the need for
hydraulic heating. This includes immersion heaters or any other
electric or residual heating elements, and can further save
electrical power and space required for breakers, cables, or any
additional voltage transformers.
[0033] An additional advantage to eliminating hydraulic power for
ancillary units in a hydraulic fracturing system is the reduction
of interconnecting cables between the ancillary mixing equipment
(e.g., blender, hydration unit) and the auxiliary trailer. These
cables are often the limiting factor that dictates the placement of
the equipment on site, in that the ancillary equipment can only be
positioned as far from the auxiliary trailer as the associated
cables will reach, while the auxiliary trailer can only be as far
from the switchgear as the associated cable will reach. Oftentimes
the desired equipment placement is not possible due to one piece of
equipment having cables that are too short. Producing longer power
and communication cables is expensive as well as inefficient, as
power losses and signal degradation become limiting factors with
cable length.
[0034] If all VFDs, soft starters, and breakers can be placed on
the hydration and blender units, or other ancillary hydraulic
fracturing equipment, then up to ten interconnecting cables per
blender and four interconnecting cables per hydration unit can be
removed, allowing for the fleet-wide reduction of up to 24 power
and signal cables, for example. These interconnecting cables are a
contributor to longer rig-in and rig-out times experienced on the
electric fleets as compared to diesel fleets. These cables also
require an enclosed trailer to transport the cables between well
pads, resulting in an increased risk of failure and damage every
time the cables are disconnected and stowed for transport.
Eliminating these cables and connections will save time and reduce
cable costs, and will increase fleet-wide reliability.
[0035] Other aspects and features of the present disclosure will
become apparent to those of ordinary skill in the art after reading
the detailed description herein and the accompanying figures.
BRIEF DESCRIPTION OF DRAWINGS
[0036] Some of the features and benefits of the present disclosure
having been stated, others will become apparent as the description
proceeds when taken in conjunction with the accompanying drawings,
in which:
[0037] FIG. 1 is an overhead schematic diagram of a physical
arrangement of components of a hydraulic fracturing system at a
well site, according to an embodiment.
[0038] FIG. 2 is a schematic perspective view of a blender trailer,
powered by a hydraulic pump, for use in a hydraulic fracturing
system, according to an embodiment.
[0039] FIG. 3 is a schematic perspective view of a blender trailer,
powered by an electric motor, for use in a hydraulic fracturing
system, according to an embodiment.
[0040] FIG. 4 is a schematic perspective view of auger, proppant
hopper, and mixing tub components of the blender trailer of FIG. 3,
according to an embodiment.
[0041] FIG. 5 is a schematic perspective view of a hydration unit
trailer, powered by a hydraulic pump, for use in a hydraulic
fracturing system, according to an embodiment.
[0042] FIG. 6 is a schematic perspective view of a hydration unit
trailer, powered by an electric motor, for use in a hydraulic
fracturing system, according to an embodiment.
[0043] While the disclosure will be described in connection with
the preferred embodiments, it will be understood that it is not
intended to limit the disclosure to that embodiment. On the
contrary, it is intended to cover all alternatives, modifications,
and equivalents, as may be included within the spirit and scope of
the disclosure as defined by the appended claims.
DETAILED DESCRIPTION OF DISCLOSURE
[0044] The method and systems of the present disclosure will now be
described more fully hereinafter with reference to the accompanying
drawings in which embodiments are shown. The method and system of
the present disclosure may be in many different forms and should
not be construed as limited to the illustrated embodiments set
forth herein; rather, these embodiments are provided so that this
disclosure will be thorough and complete, and will fully convey its
scope to those skilled in the art. Like numbers refer to like
elements throughout. In an embodiment, usage of the term "about"
includes +/-5% of the cited magnitude. In an embodiment, usage of
the term "substantially" includes +/-5% of the cited magnitude.
[0045] It is to be further understood that the scope of the present
disclosure is not limited to the exact details of construction,
operation, exact materials, or embodiments shown and described, as
modifications and equivalents will be apparent to one skilled in
the art. In the drawings and specification, there have been
disclosed illustrative embodiments and, although specific terms are
employed, they are used in a generic and descriptive sense only and
not for the purpose of limitation.
[0046] Described herein are example methods and systems for
powering ancillary units of a hydraulic fracturing system with
electric power.
[0047] FIG. 1 shows an overhead schematic view of an example of a
hydraulic fracturing system 100 arrangement at a well site,
according to an embodiment. In the illustrated example, up to about
13.8 kV or more of power can be supplied from a plurality of
switchgear trailers (not shown) to a plurality of transformers
105-a, 105-b, 105-c, 105-d, 105-e, 105-f, 105-g, 105-h. The
transformers 105-a, 105-b, 105-c, 105-d, 105-e, 105-f, 105-g, 105-h
can supply power at a stepped-down voltage of down to about 600V or
less to a plurality of variable-frequency drive (VFD) houses 110-a,
110-b, 110-c, 110-d, 110-e, 110-f, 110-g, 110-h. The VFD housings
110-a, 110-b, 110-c, 110-d, 110-e, 110-f, 110-g, 110-h can in turn
control power provided to a plurality of fracturing pumps 115-a-1,
115-a-2, 115-b-1, 115-b-2, 115-c-1, 115-c-2, 115-d-1, 115-d-2,
115-e-1, 115-e-2, 115-f-1, 115-f-2, 115-g-1, 115-g-2, 115-h-1,
115-h-2.
[0048] Each of the transformers, VFD housings, and fracturing pumps
can be housed on a plurality of fracturing pump trailers 112-a,
112-b, 112-c, 112-d, 112-e, 112-f, 112-g, 112-h, arranged parallel
with respect to each other, as in the illustrated embodiment. In
other embodiments, the plurality of trailers may be arranged
perpendicularly, in series, or in any other arrangement suitable
for the hydraulic fracturing operation. In some embodiments, each
VFD housing 110-a, 110-b, 110-c, 110-d, 110-e, 110-f, 110-g, 110-h
is positioned on a trailer with two fracturing pumps 115-a-1,
115-a-2, 115-b-1, 115-b-2, 115-c-1, 115-c-2, 115-d-1, 115-d-2,
115-e-1, 115-e-2, 115-f-1, 115-f-2, 115-g-1, 115-g-2, 115-h-1,
115-h-2 positioned thereon, while the transformers 105-a, 105-b,
105-c, 105-d, 105-e, 105-f, 105-g, 105-h-are positioned on separate
trailers. In other embodiments, other combinations of transformers,
VFD housings, and fracturing pumps can be arranged on one or more
trailers. Although illustrated in FIG. 1 as having eight sets of
transformers, VFD housings, and fracturing pumps, in other
embodiments, any of 1, 2, 3, 4, 5, 6, 7, 9, 10 or more of each
element can be included in the hydraulic fracturing system 100.
[0049] In some embodiments, fracturing pumps 115-a-1, 115-a-2,
115-b-1, 115-b-2, 115-c-1, 115-c-2, 115-d-1, 115-d-2, 115-e-1,
115-e-2, 115-f-1, 115-f-2, 115-g-1, 115-g-2, 115-h-1, 115-h-2 can
include diesel or dual-fuel fracturing pumps, which can be used to
supplement an electric fleet. For example, the diesel or dual-fuel
fracturing pumps can be fluidly connected to and combined with the
fluid output of electric fracturing pumps. Together, the electric
and non-electric fracturing pumps can be used to provide power for
fracturing the well.
[0050] In the illustrated embodiment, two additional transformers
105-i, 105-j receive up to about 13.8 kV power or more from a
switchgear trailer and provide a stepped-down voltage of down to
about 600V or less to sand equipment 145, a hydration unit 160,
blenders 165-a, 165-b, and/or a chemical additive unit 170. Power
from transformers 105-i, 105-j can also be indirectly supplied to
data van 155 via a VFD housing 130-a, 130-b of one or more blenders
165-a, 165-b, according to the illustrated embodiment.
[0051] In typical, hydraulically-powered systems, two or more
auxiliary trailers (not shown) would be included in the hydraulic
fracturing system 100 to house the hydraulic equipment and related
power equipment such as VFDs, soft starters, motor control centers
(MCCs), and breakers, for example. In the illustrated embodiment,
the two transformers 105-i, 105-j are provided in lieu of the two
auxiliary trailers, as bulky hydraulic motors may not be needed to
power the ancillary equipment. The remaining equipment typically
stored on the auxiliary trailers, such as the VFDs, soft starters,
motor control centers, and breakers, can be relocated to the
individual trailers housing each of the hydration unit 160,
blenders 165-a, 165-b, and chemical additive unit 170. For example,
according to an embodiment of the present disclosure, the entire
hydraulic system typically positioned on and used to power each
piece of ancillary equipment in known hydraulically-powered systems
can be removed and replaced with a VFD housing.
[0052] Since the required equipment for the auxiliary trailer is
partially or entirely eliminated by the substitution of electric
power for hydraulic power, the embodiment illustrated in FIG. 1 can
allow for elimination of the auxiliary trailer. With each of the
VFDs, soft starters, MCCs, and breakers moved to respective blender
165-a, 165-b and hydration unit 160 trailers, the auxiliary trailer
can be replaced with one or more transformers 105-i, 105-j.
[0053] Replacing the two typical auxiliary trailers with two 13.8
kV to 600V transformers 105-i, 105-j can conserve space at the
hydraulic fracturing well site 100. The mixing equipment composed
of two blenders 165-a, 165-b, a hydration unit 160, and a chemical
additive unit 170 can each include a VFD housing 130-a, 130-b,
130-c, 130-d, respectively, in place of where the hydraulic power
equipment would have been positioned on each respective trailer, as
discussed in more detail below with respect to FIGS. 2, 3, 5, and
6.
[0054] In the illustrated embodiment, the two blender units 165-a,
165-b can be powered through separate transformers 105-i, 105-j.
This configuration can provide redundancy such that if one
switchgear, turbine, or transformer has a failure, the other
blender will still be operational for flushing the wellbore and
maintaining circulation.
[0055] According to an embodiment, blenders 165-a, 165-b can
operate very similarly to a fracturing pump, with only a
transformer 105-i, 105-j supplying power to the trailer on which
each blender 165-a, 165-b is positioned, and with all supporting
breakers and controls being locally positioned at blenders 165-a,
165-b. These transformers 105-i, 105-j can be small, skid-mounted
enclosures that can be positioned close to the blenders 165-a,
165-b at the hydraulic fracturing system 100 well site, and can
include connections for two or more pieces of equipment. Each
connection can include six cables plus a ground cable, according to
an embodiment, where the six cables are composed of two cables for
each of the three power phases. In other embodiments, other numbers
and combinations of cables, ground cables, and power phases can be
used.
[0056] Typical electric motors may use 600V, three-phase electrical
power, according to some embodiments. Alternate embodiments may use
4160V, 480V, or any other feasible three-phase voltage instead.
Single-phase alternating current (AC) voltage can be used as well,
with voltages including but not limited to 120V or 240V. In some
embodiments, DC voltage, for example having simplified controls
(e.g., lack of a VFD) can be used for smaller motors, at voltages
including 5V, 12V, 24V, 48V, or any other reasonable DC
voltage.
[0057] In the illustrated example, hydration unit 160 includes a
trailer positioned to house mixing vessels and fluid pumps 135 and
a VFD housing 130-c. The hydration unit 160 can hold up to 300
barrel units (bbl) of fluid in a mixing vessel 135, according to an
embodiment, and between 200 bbl to 225 bbl of fluid according to
another embodiment. The hydration unit 160 can supplement the
capabilities of the blenders 165-a, 165-b by pulling on fluid
through a suction manifold. Typically, fluid pulling is provided by
a hydraulically powered fluid pump; however, in an embodiment
according to the present disclosure, fluid pulling can be provided
instead by an electrically powered fluid pump. The electric motor
operating the fluid pump can be positioned on the trailer housing
hydration unit 160, for example between the mixing vessels and
pumps 135 and VFD housing 130-c in an embodiment, or under the VFD
housing 130-c in another embodiment.
[0058] The mixing vessel 135 of hydration unit 160 can be used to
premix chemicals for use in hydraulic fracturing operations and can
act as a buffer in the event of a fluid delivery problem. For
example, if a fracturing stage is being pumped at a fluid rate of
70 barrels per minute (bpm) when water transfer to the well site is
lost, the mixing vessel 135 can provide operators with a
three-minute window to determine the problem causing the lost water
transfer and to resume water transfer, or to flush the surface
equipment and shut down pumping operations.
[0059] The mixing vessel 135 can include an instrumentation and
control package, which can allow the mixing vessel 135 to monitor,
for example, any of fluid rate, pressure, viscosity, pH,
temperature, and chemical additive rates in either automatic or
manual modes of operation. All valves, paddles, and pumps
associated with the mixing vessel 135 can be controlled and powered
through an onboard circuit positioned on the trailer housing
hydration unit 160.
[0060] A plurality of small electric motors can be used with
various components associated with the hydration unit 160. For
example, an electric motor can be used to rotate mixing paddles in
a large mixing compartment of the hydration unit 160, while another
electric motor can be used with a suction manifold to pull of the
fluid, and still another electric motor can be used for driving the
chemical pumps associated with the hydration unit 160. Each
electric motor can be positioned at various discrete positions
about the hydration unit 160 trailer in some embodiments, or can be
clustered in other embodiments.
[0061] Chemical additive unit 170 can include a trailer positioned
to house chemical pumps 140 and VFD housing 130-d. In some
embodiments, a fracturing fleet can utilize four or five chemical
pumps, depending on the particular needs of the fracturing site, or
consumer requirements. In some embodiments, the blender units 165-a
can include five to eight chemical pumps, although in other
embodiments, one, two, three, four, nine, ten, or more chemical
pumps can be included. In some embodiments, the hydration units 160
can additionally include five or more chemical pumps, although in
other embodiments the hydration units 160 can include zero, one,
two, three, or four chemical pumps, depending on particular
fracturing site requirements or consumer preferences. In some
embodiments, where both the blender units and the hydration units
include chemical pumps, either the blender units 165-a or the
hydration units 160 can provide all the chemicals needed for the
fracturing slurry. In such embodiments, either the blender units
165-a or the hydration units 160 can serve as the primary chemical
delivery method. Because of this redundancy, if either the blender
unit or the hydration unit has a pump failure, the other,
functioning unit can serve as a backup to provide the chemicals
needed for the fracturing slurry. Thus, in some embodiments, the
blender units 165-a, 165-b can also contain chemical pumps 125-a,
125-b, such that the hydration unit 160 can serve as either the
backup chemical delivery system to the chemical delivery system of
the blender units 165, or as the primary chemical delivery system.
This backup chemical delivery system may be advantageous, for
example, in use with certain chemicals. For example, guar gel (a
viscosifier) needs time and fluid shear to properly mix and
thicken, and accordingly should be added to the slurry mixture at
the hydration unit 160. If added at one or more of the blenders
165-a, 165-b, guar gel may not have sufficient time to mix, and may
result in an improper slurry viscosity, leading to less than ideal
well production after the fracturing process is completed.
[0062] In some embodiments, chemical additive unit 170 can serve as
the primary source of chemicals for the fracturing slurry. In other
embodiments, chemical additive unit 170 can serve as the secondary
or tertiary source of chemicals, after the hydration unit 160
and/or blenders 165-a, 165-b. The chemical additive unit 170 can
include several chemical pumps and vats, and can be used to
supplement the blenders 165-a, 165-b, particularly when the
hydraulic fracturing operation requires multiple different
chemicals or a particular chemical pump redundancy. In some
embodiments, up to a dozen or more chemical pumps can be used with
chemical additive unit 170. In some embodiments, the chemical pumps
can be configured for use with liquid chemicals, while in other
embodiments the chemical pumps can be dry chemical augers. In the
latter case, a small hopper with a small, screw-type auger can pull
the powder chemical from the hopper, and can drop the powder
chemical into a mixing tub. Each blender can include one or more of
these hopper and auger combinations, in some embodiments. In other
embodiments, a larger dry chemical additive system can be
incorporated into a hydration unit with a large mixing tub.
[0063] Like the hydration unit 160 and blenders 165-a, 165-b, the
chemical additive unit 170 can be designed to be operated without
the use of hydraulics, instead employing electric motors. The
substitution of electrical power for hydraulic power can provide
multiple advantages, as previously discussed, including saving
space, enhancing reliability and versatility, improving ecological
impact, being lighter, quieter, and safer, presenting fewer fire
hazards.
[0064] The one or more chemical pump 140 of chemical additive unit
170 can include one or more electric motor, which can be stacked
between the VFD housing 130-d and the chemical additive unit 170 in
some embodiments, or can be installed underneath the VFD housing
130-d in other embodiments. The electric motors can be small enough
to be positioned in various configurations around the chemical pump
140 trailer. The electric motors can operate components of the
chemical pump 140 in lieu of the use of hydraulic power, the latter
of which is typically provided from one or more auxiliary
trailers.
[0065] Blenders 165-a, 165-b can include slurry mixing units 120-a,
120-b, pumps 125-a, 125-b, and VFD housings 130-a, 130-d. The
slurry mixing units 120-a, 120-b and pumps 125-a, 125-b can each be
electrically coupled to a respective electric motor to drive
operation of the mixing units and pumps. In an embodiment, blenders
165-a, 165-b can further include a battery powered electric hopper
raise/lower system to facilitate "spotting" the blender during
rig-in. This raise/lower system can allow a proppant hopper to be
lowered into place before turbine power is connected, so that
operators can see where the hopper will rest in relation to a sand
conveyor. With the introduction of electrically actuated valves
according to the present disclosure, the raise/lower system can be
tied into that battery system. This can allow the blender operator
to open a manifold crossover in the event of an electrical failure
(e.g., turbine shutdown, ground fault, cable disconnection, breaker
opening, etc.). The manifold crossover can be a pipe that spans
from the suction manifold to the discharge manifold, bypassing the
mixing tub, discharge pump, and metering instrumentation. This
configuration also provides an added operational backup, in which,
if the primary blender loses power, the raise/lower system can
still open the manifold crossover to allow the hydration unit 160
to boost water through the inoperable primary blender manifold to
the secondary blender without shutting down the fracturing
operation. This can prevent millions of dollars wasted during
downtime by maintaining circulation in the well to prevent a
"screen out," in which additional nonproductive services such as
coil tubing, flow back, or a workover rig will be required to clean
out the well.
[0066] FIG. 2 shows a perspective schematic view of an example 200
of a hydraulically powered hydraulic fracturing blender 265, as is
typically used in hydraulic fracturing systems. The hydraulic
fracturing blender 265 can be used to mix multiple dry and liquid
chemicals and different types of proppant (usually sand). The
blender 265 can pull fluid in through a suction manifold with a
hydraulically powered suction pump and discharge the mixed or
unmodified fluid at over 100 pounds per square inch (psi) and 130
barrels per minute (bpm) through a discharge manifold with a large
electrically-driven discharge pump. Proppant can be deposited in
proppant hopper 246, and can move up rotating auger 248, before
being dumped into mixing tub 222. Hoses 252 can supply chemicals
and fluids to be mixed with the proppant in mixing tub 222, and the
mixed product can be pumped to the fracturing pumps through the
discharge manifold.
[0067] A typical blender 265 as illustrated can also include a
monitoring and controls instrumentation package, which allows the
blender 265 to monitor and control fluid density, fluid rate, fluid
pressure, chemical additive rates, and proppant additive rates, in
either manual or automatic modes. In the shown embodiment, all
pumps (except for the discharge pump and air blowers), valves, and
augers can be controlled and powered through a hydraulic circuit
275, positioned at a front end of the trailer on which blender 265
is positioned.
[0068] FIG. 3 shows a perspective schematic view of an example 300
of an electrically powered hydraulic fracturing blender 365,
according to an embodiment. Blender 365 shows an alternative
embodiment to blender 265 as illustrated in FIG. 2, providing an
example configuration in which the hydraulic circuit 275 powering
blender 265 is replaced with one or more electric motor 390 and a
VFD 380 to provide electrical, rather than hydraulic, operation to
blender 365. In some embodiments, an electric motor 390 can be
provided for each suction pump, chemical pump, and/or tub paddle
associated with the blender 365. As illustrated in FIG. 3, in
examples where the electric motor 390 operates a sand auger
associated with blender 365, the electric motor 390-a, 390-b, 390-c
can be positioned in any of three distinct positions with respect
to blender 365, as discussed in more detail below with respect to
FIG. 4, or in any other appropriate positions on the blender
trailer.
[0069] Each of the elements of blender 265, including mixing tub
222, proppant auger 248, proppant hopper 246, and hoses 252 can
operate identically in blender 365. For example, proppant can be
deposited in proppant hopper 346, and can move up rotating auger
348, before being dumped into mixing tub 322. Hoses 352 can supply
chemicals and fluids to be mixed with the proppant in mixing tub
322, and the mixed product can be boosted to the fracturing pumps
from the discharge manifold. However, unlike the elements of
blender 265, which are hydraulically powered, each element of
blender 365 can be operated by an electric motor 390, in the
absence of hydraulic circuit 275. With hydraulic circuit 275
removed, the trailer housing blender 365 can have sufficient space
at the front of the trailer to support a VFD 380 to control and
deliver power to the electric motor 390-a, 390-b, 390-c to
mechanically rotate the proppant augers, as discussed in more
detail with respect to FIG. 4 below.
[0070] FIG. 4 shows a side schematic view of an example 400 of the
proppant auger portion 448 of the electrically powered hydraulic
fracturing blender 365 as illustrated in FIG. 3, according to an
embodiment. As discussed above with respect to FIG. 3, proppant can
be deposited into proppant hopper 446, and can be moved up rotating
proppant auger 448 to be dumped into mixing tub 422. In some
embodiments, the proppant auger 448 of blender unit 365 can include
three large proppant augers on the rear of the trailer, which lead
from the hopper 446 to the mixing tub 422. In other embodiments, 1,
2, 4, or more proppant augers can be utilized. Chemicals and fluids
can be added to mixing tub 422 to be mixed with the proppant, and
the mixed proppant can be discharged through a discharge manifold
to the fracturing pumps.
[0071] As discussed above with respect to FIGS. 2 and 3, the
proppant auger 448 is typically hydraulically driven, often by a
hydraulic motor 495 positioned on the top of the proppant auger
tube 448. As the trailer housing the fracturing blender 365 is
mobile, roadway height restrictions must be taken into account in
positioning the components of the blender 365 on the trailer. In
typical, hydraulically-powered blenders (as illustrated in FIG. 2),
the hydraulic motor 495 may be positioned at a top end of proppant
auger 448. Hydraulic motors are typically divided into two
parts--the hydraulic pump and the hydraulic motor--with pressurized
hoses connecting each part. Because of this configuration, each
part of the hydraulic motor individually takes up less space than
does a typical electric motor. A typical electric motor is
constructed as a single unit, such that replacing a component of
the hydraulic motor with the electric motor in the same position as
the component of the hydraulic motor may result in the trailer
housing the blender 365 exceeding roadway height restrictions.
[0072] Thus, in the electrically-powered blender 365 illustrated in
example 400, the hydraulic motor 495 may be removed, and an
electric motor may be positioned on the sloped surface of the
proppant auger 448, such that the larger electric motor does not
extend higher than the smaller hydraulic motor 495 would have
extended. For example, in an embodiment, the electric motor 490-a
may be positioned near an upper end of the top face of the proppant
auger 448, parallel to the proppant auger tube. In this
configuration, a chain, gear, or belt coupling, or another
appropriate coupling, may be used to drive the auger. In another
embodiment, the electric motor 490-b may be positioned near a lower
end of the bottom face of the proppant auger 448, and the electric
motor may be configured to spin the auger from the bottom. In still
another embodiment, the electric motor 490-c may be positioned at a
bottom end of the proppant auger 448. Various other configurations
are also contemplated, any of which enable the arrangement of the
elements of blender 365 on the trailer to comply with roadway
restrictions.
[0073] Electric motor 490-a, 490-b, 490-c can be a 600 V,
three-phase motor in an embodiment, or can be a single-phase motor
having a different voltage in other embodiments. In some examples,
the electric motor may be small, for example the size of a small
trashcan, while in other examples the electric motor may be larger.
In examples where the electric motor is small, the electric motor
may be configured to dissipate heat independently, such that a
cooling apparatus is not needed. In some examples the electric
motor can use AC power, while in other examples the electric motor
can use DC power. The electric motor may work in conjunction with a
transformer in some examples. In some embodiments, the electric
motor can generate at least about 30-40 horsepower (HP) in order to
provide sufficient power to rotate proppant auger 448. In other
embodiments, other electric motor power levels are contemplated;
for example, an electric motor for use with a chemical pump may
operate around 15 HP, an electric motor for use with augers may
operate around 50 HP, and an electric motor for use with a suction
pump may operate around 200 HP. The electric motor can be an
induction motor or a permanent magnet motor, according to various
embodiments.
[0074] FIG. 5 shows a perspective schematic view of an example 500
of a typical hydraulically-powered hydration unit 560. The
hydration unit 560 can supplement the capabilities of the blender
365, as discussed above with reference to FIGS. 3 and 4. In the
illustrated example 500, hydration unit 560 can be powered by a
hydraulic circuit 575, an electric motor (HPU) for which is
illustrated in FIG. 5 as positioned at a front end of the hydration
unit 560 trailer.
[0075] The hydration unit 560 is configured to pull on fluid
through a suction manifold with a hydraulically powered fluid pump,
and can hold up to about 300 bbl of fluid in a mixing vessel 562.
The mixing vessel 562 can be used to premix chemicals before use in
the hydraulic fracturing process, and can act as a buffer in the
event of a fluid delivery problem. For example, if a fracturing
stage is being pumped at a fluid rate of 70 bpm when water transfer
to the wellsite is lost, the hydration unit 560 can provide the
operators with a three-minute window in which to determine the
problem and resume water transfer, or to flush the surface
equipment and shut down pumping operations.
[0076] Onboard hydration unit 560 can be an instrumentation and
control package that allows the hydration unit 560 to monitor fluid
rate, pressure, viscosity, pH, temperature, and chemical additive
rates in either automatic or manual modes of operation. All valves,
paddles, and pumps can be controlled and powered through an onboard
hydraulic circuit.
[0077] FIG. 6 shows a perspective schematic view of an example 600
of an electrically powered hydraulic fracturing hydration unit 660,
according to an embodiment. Hydration unit 660 shows an alternative
embodiment to hydration unit 560 as illustrated in FIG. 5,
providing an example configuration in which the hydraulic circuit
575 powering hydration unit 560 is replaced with one or more
electric motor 690 and a VFD house 680 to provide electrical,
rather than hydraulic, operation of hydration unit 660. In some
embodiments, an electric motor 690 can be provided for each of the
one or more chemical pumps, suction pumps, and mixing paddles
associated with hydration unit 600.
[0078] The remaining components of hydration unit 660, such as
mixing vessel 662, may operate as described above with respect to
FIG. 5. However, components of hydration unit 660, such as suction
pumps and mixing paddles, may be driven by one or more electric
motors 690 via VFD housing 680, rather than by a hydraulic circuit
575. In some embodiments, the electric motor 690-b may be
positioned between mixing vessel 662 and VFD housing 680. In other
embodiments, the electric motor 690-a may be positioned in front
of, behind, or under VFD housing 680. Alternate electric motor
690-a, 690-b positions on the hydration unit 660 trailer are also
contemplated. As discussed above with respect to the hydraulic
fracturing blender of FIGS. 3 and 4, in some embodiments it may be
advantageous to consider roadway height regulations in determining
where to position the electric motor 690-a, 690-b. For example,
positioning the electric motor 690-a, 690-b atop mixing vessel 662
may result in the overall height of the hydration unit 660 trailer
exceeding roadway height limitations in some cases, but may be
permissible in other instances, depending upon specific
regulations.
[0079] In some embodiments, the removed hydraulic circuit 575 may
be replaced by VFD housing 680 on the front portion (or "tongue")
of the trailer. In other embodiments, rather than placing the VFD
housing 680 on the tongue of the trailer, the front of the trailer
may be left as an open deck with or without perimeter rails, such
that the open space can be used for chemical tote or other
component storage. For example, hydraulic fracturing sites often
include at least one flatbed or drop deck trailer provided for
storing chemical totes thereon; however, use of separate trailers
for chemical totes may necessitate the use of several independent
chemical lines spanning between the totes and the hydration unit
660 trailer. By instead storing the chemical totes on the hydration
unit 660 trailer, both the separate storage trailers and the
chemical lines may be eliminated, thereby conserving space at the
hydraulic fracturing site and limiting the use of materials, such
as chemical lines, which may be expensive, faulty, dangerous, and
cumbersome.
[0080] In another embodiment, a small acid vessel can be positioned
on the vacant trailer deck position. This embodiment may be useful
for trigger toes (e.g., where no sand is pumped, the well is
pressurized to open a sleeve called the "toe," and small quantities
of water and acid are displaced to open the formation and
surrounding cement) or for low-rate fracturing jobs (e.g.,
conventional or non-shale jobs, typically performed at less than 50
bpm or even as low as 5 bpm, as opposed to 70-120 bpm for shale
jobs). In one example, the acid vessel could hold about 500 to 1500
gallons of acid, for example hydrochloric acid (HCL) at a
concentration of about 15% to 30%, and could be completely enclosed
and refillable from a supply acid tanker. Other acids and different
concentrations are also feasible. In this configuration, extra
landing gear to support the weight of the trailer while rigged-in
may be required.
[0081] In examples where the equipment is dedicated to low-rate
jobs, pump downs only, or trigger toes, and is specifically
designed for a maximum of about 60 bpm (as opposed to about 130 bpm
for typical electric blenders), for example, a small open-top
mixing tank may be positioned on the open deck space to combine the
qualities of the hydration unit and blender onto a single unit.
According to such an embodiment, the single unit may include a
large electric discharge motor (e.g., about 1000 HP or more) for
boosting fluid to fracturing pumps capable of about 120 psi charge
pressure, in one example. The single unit could also include
multiple chemical pumps (e.g., 5-10 liquid pumps, 2-4 dry chemical
hoppers), and optional sand augers if the unit will be used for
low-rate well stimulation. In some embodiments, the single unit
could further include an optional chemical premixing tank with an
open top and mixing paddles (having, for example, 50-100 bbl
capacity) plumbed into the suction lines of the unit. This
configuration could take the place of the HPU motor and hydraulics
in typical electric blender models.
[0082] Additional elements of the single unit could include an
optional acid tank plumbed into the discharge lines; optional open
deck space for chemical totes, pallets, or vats; or an optional VFD
housing with all required breakers, soft starters, and VFDs for
reduced interconnecting cables. The single unit could also include
a supplemental mixing tub (e.g., having about 5-10 bbl volume) if
sand augers are installed; a suction pump for drawing water from a
source; and/or a full instrumentation package (e.g., Densometer,
suction and discharge flow meters, suction and discharge pressure
transducers, pH probe, fluid temperature probe, viscometer,
chemical flow meters, and others)
[0083] In the described example single unit, the purpose of the
large open top mixing tank can be to allow for the premixing of
gel. Gel is usually made of guar, but can be composed of synthetic
origins as well, and can be added to the vat in condensed liquid
form or in a powder form. Premixing may be required where the
viscosifier can take several minutes to hydrate, and may need extra
time to mix the gel with water. Facilitating this premixing is the
typical role of the hydration unit, in addition to containing
supplemental chemical pumps and acting as a fluid buffer in the
event of an issue with the water supply. If a mixing tank is
installed, extra landing gear may be required to support the weight
of the extra fluid once the unit is rigged in and filled.
[0084] The present disclosure described herein, therefore, is well
adapted to carry out the objects and attain the ends and advantages
mentioned, as well as others inherent therein. While a presently
preferred embodiment of the disclosure has been given for purposes
of disclosure, numerous changes exist in the details of procedures
for accomplishing the desired results. These and other similar
modifications will readily suggest themselves to those skilled in
the art, and are intended to be encompassed within the spirit of
the present disclosure disclosed herein and the scope of the
appended claims.
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