Note: Descriptions are shown in the official language in which they were submitted.
CA 02945580 2016-10-17
INDEPENDENT CONTROL OF AUGER AND HOPPER ASSEMBLY
IN ELECTRIC BLENDER SYSTEM
BACKGROUND OF THE INVENTION
1. Field of Invention
[0001] The present disclosure relates to operations in a subterranean
formation. In particular, the
present disclosure relates to a hydraulic fracturing system.
2. Description of Related Art
[0002] Hydraulic fracturing is a technique used to stimulate production from
some hydrocarbon
producing wells. The technique usually involves injecting fluid into a
wellbore at a pressure
sufficient to generate fissures in the formation surrounding the wellbore.
Typically, the
pressurized fluid is injected into a portion of the wellbore that is pressure
isolated from the
remaining length of the vvellbore so that fracturing is limited to a
designated portion of the
formation. The fracturing fluid slurry, whose primary component is usually
water, includes
proppant (such as sand or ceramic) that migrate into the fractures with the
fracturing fluid slurry
and remain to prop open the fractures after pressure is no longer applied to
the wellbore. Other
than water, potential primary fluids for the slurry include nitrogen, carbon
dioxide, foam
(nitrogen and water), diesel, or other fluids. The fracturing slurry may also
contain a small
component of chemical additives, which can include scale build up inhibitors,
friction reducing
agents, viscosifiers, stabilizers, pII buffers, acids, biocides, and other
fluid treatments. In
embodiments, the chemical additives comprise less than 1% of the fracturing
slurry.
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[0003] The fluids are blended with a proppant in the blender unit. The
proppant is supplied from
a nearby proppant source via a conveyor into a hopper associated with the
blender unit. The
hopper associated with the blender unit can be difficult to align with the
proppant feed. This
difficulty arises, in part, because during transport on a trailer, the hopper
of the blender unit is
typically placed in a raised position. In order to properly position the
hopper relative to the
conveyor, so that the hopper can receive proppant, three steps are necessary,
including 1) the
trailer carrying the blender unit must be aligned with the conveyor, 2) power
must be connected
to the blender unit, and 3) the hopper must be lowered into position to
receive proppant from the
conveyor.
[00041 The problem lies in the necessary order of these three steps in known
systems. For
example, typically, power to the blender unit is not connected until all
trailers and equipment are
in place at the well site. Because the hopper cannot be lowered into position
until power is
connected to the blender unit, this means that the blender unit trailer must
be positioned relative
to the conveyor while the hopper unit is in the elevated position. The problem
with this is that
when in the hopper is in the elevated position, it is very difficult to tell
when the trailer is
properly aligned with the conveyor. Furthermore, by the time power is
connected, allowing the
hopper to be lowered, it is too late to reposition the blender unit trailer if
the hopper does not
properly align with the conveyor.
SUMMARY OF THE INVENTION
100051 Disclosed herein are embodiment systems and methods of hydraulic
fracturing with
independent control of an auger and hopper assembly. In embodiments, a
hydraulic fracturing
system includes a blender unit capable of mixing proppant and fluid. A first
power supply, such
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as an electric generator, can be used to power the blender unit. The system
can further include
an auger and hopper assembly, which includes one or more augers, a hopper, and
a hydraulic
cylinder. The hopper can receive proppant through an upper opening and
transport the proppant
out of the hopper using one or more augers. The hydraulic cylinder, when
activated by one or
more actuators for example, can move the auger and hopper assembly between a
stowed position
and a deployed position.
[0006] A second power supply. such as a battery, can power the auger and
hopper assembly.
The second power supply can operate independently of the first power supply.
In other words, in
embodiments, the battery can supply power to the auger and hopper assembly
with no power
input from the electric generator. The battery, however, can be recharged by
the electric
generator when the electric generator is on. Thus, the first power supply can
recharge the second
power supply, but the second power supply operates independently when powering
the auger and
hopper assembly. In embodiments, the second power supply is a 12-volt direct
current battery.
In embodiments, one or more batteries are connected in parallel to form a
power supply.
[0007] The hydraulic fracturing system can further include a blender tub
positioned beneath the
auger outlets. When the auger and hopper assembly is in the deployed position,
the auger outlets
become aligned with upper opening of the blender tub. That is, the approximate
center of the
blender tub can be positioned below the auger outlets when the auger and
hopper assembly is in
the deployed position.
[0008] Methods according to various embodiments can include positioning a
blender unit near a
proppant source. The blender unit can be mobile. For example, it can be
positioned on a truck
or trailer that includes various other components of a blender system, such as
a blender tub with
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an upper opening, and an auger and hopper assembly with the hopper having an
upper opening
and the auger outlets being positioned above the center of the blender tub. An
example method
can further include deploying the auger and hopper assembly from a stowed
position to a
deployed position. When the assembly is in the deployed position, the hopper
will be aligned
with a proppant feed from the proppant source. For example, the proppant can
be fracturing
sand, and the proppant feed can be a sand conveyor configured to deliver sand
to the hopper.
Deploying the assembly, according to various embodiments, includes powering
one or more
actuators with a battery. In addition, the blender unit can be connected to a
power supply, which
is independent from the battery that powers the actuators of the auger and
hopper assembly.
100091 When the auger and hopper assembly is moved to the deployed position,
proppant from
the proppant feed can be received into the hopper through the upper opening of
the hopper. One
or more augers with inlets positioned to receive proppant from the hopper can
move proppant out
of the hopper. The auger outlets are positioned above the blender tub when the
auger and hopper
assembly is in the deployed position. Proppant from the hopper can then be
released via the
auger outlets into the blender tub, where it is received by the blending unit.
The blending unit
can then mix the proppant with a fluid to prepare a fracturing slurry. This
slurry can be pumped
to a fracturing pump system, where it can be highly pressurized and pumped
into a subterranean
formation, as discussed in more detail below,
BRIEF DESCRIPTION OF DRAWINGS
[0010] Some of the features and benefits of the present invention having been
stated, others will
become apparent as the description proceeds when taken in conjunction with the
accompanying
drawings, in which:
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[0011] FIG. 1 is a schematic example of a hydraulic fracturing system
according to certain
embodiments;
[0012] FIG. 2 is a side perspective view of a blender system with an auger and
hopper assembly
in a stowed position according to certain embodiments;
[0013] FIG. 3 is a side perspective view of a blender system with an auger and
hopper assembly
in a deployed position according to certain embodiments;
[0014] FIG. 4 is a view of a portion of a blender system with an auger and
hopper assembly in a
deployed position according to certain embodiments;
[0015] FIG 5 is a view of a portion of a blender system with an auger and
hopper assembly in a
stowed position according to certain embodiments;
[0016] FIG 6 is a view of a portion of a blender system according to certain
embodiments; and
[0017] FIG. 7 is a view of a pump and motor assembly according to certain
embodiments.
[0018] While the invention will be described in connection with certain
embodiments, it will be
understood that it is not intended to limit the invention to those
embodiments. On the contrary, it
is intended to cover all alternatives, modifications, and equivalents, as may
be included within
the spirit and scope of the invention as defined by the appended claims.
DETAILED DESCRIPTION OF INVENTION
[0019] The method and system 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
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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 +1- 5% of the cited magnitude.
In an
embodiment, usage of the term -substantially" includes +/- 5% of the cited
magnitude.
[0020] 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
arc employed, they are used in a generic and descriptive sense only and not
for the purpose of
limitation.
[0021] Figure 1 is a schematic example of a hydraulic fracturing system 10
that is used for
pressurizing a wellbore 12 to create fractures 14 in a subterranean formation
16 that surrounds
the wellbore 12. Included with the system I 0 is a hydration unit 18 that
receives fluid from a
fluid source 20 via line 22, and also selectively receives additives from an
additive source 24 via
line 26. Additive source 24 can be separate from the hydration unit 18 as a
stand-alone unit, or
can be included as part of the same unit as the hydration unit 18. The fluid,
which in one
example is water, is mixed inside of the hydration unit 18 with the additives.
In an embodiment,
the fluid and additives are mixed over a period of time to allow for uniform
distribution of the
additives within the fluid.
[0022] In the example of Figure 1, the fluid and additive mixture is
transferred to a blender unit
28 via line 30. A proppant source 32 contains proppant, which is delivered to
the blender unit 28
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as represented by line 34, where line 34 can be a conveyer. Inside the blender
unit 28, the
proppant and fluid/additive mixture are combined to form a fracturing slurry,
which is then
transferred to a fracturing pump system 36 via line 38; thus fluid in line 38
includes the
discharge of blender unit 28 which is the suction (or boost) for the
fracturing pump system 36.
Blender unit 28 can have an onboard chemical additive system, such as with
chemical pumps and
augers. Optionally, additive source 24 can provide chemicals to blender unit
28; or a separate
and standalone chemical additive system (not shown) can be provided for
delivering chemicals
to the blender unit 28. In an example, the pressure of the slurry in line 38
ranges from around 80
psi to around 100 psi. The pressure of the slurry can be increased up to
around 15.000 psi by
pump system 36.
[0023] A motor 39, which connects to pump system 36 via connection 40, drives
pump system
36 so that it can pressurize the slurry. In one example, the motor 39 is
controlled by a variable
frequency drive (-VFD"). In one embodiment, a motor 39 may connect to a first
pump system
36 via connection 40 and to a second pump system 36 via a second connection
40. After being
discharged from pump system 36, slurry is pumped into a wellhead assembly 41;
discharge
piping 42 connects discharge of pump system 36 with wellhead assembly 41 and
provides a
conduit for the slurry between the pump system 36 and the wellhead assembly
41. In an
alternative, hoses or other connections can be used to provide a conduit for
the slurry between
the pump system 36 and the wellhead assembly 41. Optionally, any type of fluid
can be
pressurized by the fracturing pump system 36 to form injection fracturing
fluid that is then
pumped into the wellbore 12 for fracturing the formation 14, and is not
limited to fluids having
chemicals or proppant.
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100241 An example of a turbine 44 is provided in the example of Figure 1 and
which receives a
combustible fuel from a fuel source 46 via a feed line 48. In one example, the
combustible fuel
is natural gas, and the fuel source 46 can be a container of natural gas or a
well (not shown)
proximate the turbine 44. Combustion of the fuel in the turbine 44 in turn
powers a generator 50
that produces electricity. Shaft 52 connects generator 50 to turbine 44. The
combination of the
turbine 44, generator 50, and shaft 52 define a turbine generator 53. In
another example, gearing
can also be used to connect the turbine 44 and generator 50.
100251 An example of a micro-grid 54 is further illustrated in Figure 1, and
which distributes
electricity generated by the turbine generator 53. Included with the micro-
grid 54 is a
transformer 56 for stepping down voltage of the electricity generated by the
generator 50 to a
voltage more compatible for use by electrical powered devices in the hydraulic
fracturing system
10. In another example, the power generated by the turbine generator and the
power utilized by
the electrical powered devices in the hydraulic fracturing system 10 are of
the same voltage, such
as 4160 V so that main power transformers are not needed. In one embodiment,
multiple 3500
kVA dry cast coil transformers are utilized. Electricity generated in
generator 50 is conveyed to
transformer 56 via line 58. In one example. transformer 56 steps the voltage
down from 13.8 kV
to around 600 V. Other step down voltages can include 4,160 V, 480 V, or other
voltages. The
output or low voltage side of the transformer 56 connects to a power bus 60.
Lines 62, 64, 66,
68, 70, and 72 connect to power bus 60 and deliver electricity to electrically
powered end users
in the system 10. More specifically, line 62 connects fluid source 20 to bus
60, line 64 connects
additive source 24 to bus 60, line 66 connects hydration unit 18 to bus 60,
line 68 connects
proppant source 32 to bus 60, line 70 connects blender unit 28 to bus 60.
Another line can
connect bus 60 to an optional variable frequency drive ("VFD") (not shown).
The VFD can
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connect to motor 39. In one example, the VFD selectively provides electrical
power to motor
39 via a dedicated or shared line, and can be used to control operation of
motor 39, and thus
also operation of pump 36.
[0026] In an example, additive source 24 contains ten or more chemical pumps
for
supplementing the existing chemical pumps on the hydration unit 18 and blender
unit 28.
Chemicals from the additive source 24 can be delivered via lines 26 to the
hydration unit 18
and/or the blender unit 28. In certain embodiments, the elements of the system
10 are mobile
and can be readily transported to a wellsite adjacent the wellbore 12, such as
on trailers or
other platforms equipped with wheels or tracks.
[0027] For example, the blender unit 28 can be positioned on a trailer, such
as the exemplary
trailer illustrated in Figure 2 and Figure 3. Thus, the blender unit 28 and
various other
components can comprise a blender system 100. The blender system 100 includes
an auger
and hopper assembly 102, which includes a hopper 106. The auger and hopper
assembly 102
is capable of moving between a stowed position (Figure 2) and a generally
linearly spaced
deployed position (Figure 3). In embodiments, the stowed position is
elevationally above the
deployed position, and the auger and hopper assembly 102 can move in a
generally linear
fashion between the two positions via an angled track 112, which is positioned
between the
augers 104 and the blender tub 108. Looking at Figure 2 and Figure 3 together,
the auger and
hopper assembly 102 can begin in the stowed position as shown in Figure 2. The
auger and
hopper assembly 102 can be directed in the direction of the arrows 105 to
reach its deployed
position as shown in Figure 3. A landing gear 111 can bear the weight of the
hopper 106
when the auger and hopper assembly 102 is in the deployed position. In
embodiments, the
landing gear 111 comprises two support legs, one on each side of the hopper
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106. A bumper 109 or safety guard can also be included to keep people or
equipment from
making contact with the exposed auger bearings.
[0028] The auger and hopper assembly 102 is typically placed in the stowed
position during
transport of the blender system 100. A hitch or other suitable coupling
mechanism 120 can be
provided on one end of the blender system 100 to facilitate transport. The
blending system 100
can be towed to a desired location at an appropriate distance from a fracking
site. In the
illustrated embodiment, the blending system includes unpowered wheels 116 to
facilitate towing
and weight-bearing legs 118 to support the blending system 100 when the towing
vehicle
disengages. The legs 118 can be independently adjusted to allow an operator to
level the
blending system, or otherwise achieve a desired tilt, even while accounting
for uneven ground.
Although not required for operations, the blending system 100 can be isolated,
i.e. no longer
connected to a towing vehicle, due to space constraints in the field. Once in
position, the
blending system 100 is connected to micro-grid 54 or otherwise supplied with
main electrical
power. The main electrical unit powers the blender unit 28, enabling it to
draw fluid onboard
through a suction manifold and pump, and blend the proppant and fluid/additive
mixture to form
a fracturing slurry, which is then boosted to a fracturing pump system 36
through a discharge
pump, as described more thoroughly with respect to Figure 1.
[00291 In other words, main power is not provided to the blender system 100
until after the
blender system 100 is initially staged. In some cases, it may take days from
the time the
equipment is staged before power is produced and directed to the blender
system 100.
Moreover, the blender system 100 is typically staged early in the process
before fracking
pumps, iron, and sand equipment are positioned¨so delays to staging the
blender system 100
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hold up other portions of the process. Further still, it is very difficult and
dangerous to move
equipment after power cables have been connected.
100301 Main power is typically generated by diesel engines for diesel
equipment or by an electric
generator for electrically powered equipment. For electrically powered
equipment, an electric
generator may not arrive onsite until after the blender system 100 is in
place, or the electric
generator may be onsite, but not generating power until after the blender
system 100 is in place.
Thus, if positioning the auger and hopper assembly 102 of the blender system
100 rely
exclusively on the main power, the auger and hopper assembly 102 cannot be
raised or lowered
into an ideal placement until the main electrical power is active and
connected. In the event of a
misalignment, the entire blender system 100 would need to be repositioned,
which would be
costly, time consuming, difficult, and sometimes dangerous.
100311 Put another way, without an independent power supply for the auger and
hopper
assembly 102, the blender system 100 can be maneuvered into an incorrect
position, but it will
not be known that the hopper 106 is improperly aligned with the proppant feed
until the entire
blender system 100 is connected to a power supply, such as, for example, the
micro-grid 54
discussed above. Once the misalignment is detected, the entire blender system
100 would have
to he disconnected from the power supply in order to reposition the blender
system 100. This
process may even have to be iterated multiple times given the difficulty of
estimating whether
the hopper 106 will he properly aligned with the conveyor belt (or appropriate
proppant feed)
when in the deployed position. These iterations may involve disconnecting the
main power and
moving other equipment to allow for maneuvering the blender system 100. This
can cause hours
or days of downtime. Thus prior to being transported to a wellsite, the auger
and hopper
assembly 102 are put into a stowed position, and remain in that position,
until the main power is
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online. The main power stays online until the fracturing job is completed.
Usually the deployed
position of the auger and hopper assembly 102 is difficult to predict
accurately because the
equipment is initially positioned with the auger and hopper assembly 102 in
the stowed position.
[0032] After the fracturing job is completed, a rig down process occurs in
which equipment is
removed from the site. The main power is disconnected before the blender
system 100 is moved.
If the auger and hopper assembly 102 is in the deployed position, the blender
system 100 cannot
be moved. That is, if operators disconnected the main power from the blender
system 100
without stowing the auger and hopper assembly 102, and there was no
independent power supply
to the auger and hopper assembly 102, then the blender system 100 would be
unmovable until
main power was reconnected to the blender system for the sole purpose of
stowing the auger and
hopper assembly 102. This problem, among others, is addressed by allowing for
the auger and
hopper assembly 102 to move between the stowed position and deployed position
without the
blender system 100 needing to be connected to the main power source.
[0033] Still referring to Figure 2 and Figure 3, the blender system 100 is
mounted on a trailer. In
this example, the blender is a fracturing blender having a capability of
supplying 130 bbl/min,
and it is designed to mix slurries for fracturing treatments. The slurries,
which can be used in
hydraulic fracturing, can also include water or other fluids. In various
embodiments, the blender
system 100 can be skid, truck, or trailer mounted, and can be used on or off-
shore. The auger
and hopper assembly 102 includes one or more obliquely angled augers 104 that
lift proppant
from an attached hopper 106, and deliver the proppant to a blender tub 108 as
shown. The
system is capable of handling a wide array of tasks associated with complex
fracturing
operations in harsh oilfield conditions; and is operable in temperature ranges
of -4 F (-20 C) to
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115 F (46 C). Embodiments of the unit include 10 inch diameter pipe and a
total power rating
of 1,400 BHP (minimum). In one example, the system pumps inhibited acid.
[0034] The blender system 100 includes an independently powered auger and
hopper positioning
system to raise and lower the auger and hopper assembly 102 prior to setting
up the main
electrical power. The positioning system controls 114 are used to adjust the
position of the auger
and hopper assembly 102. In embodiments, the power supply comprises a
dedicated electric 12
VDC power supply. In one example, the positioning system includes one or more
actuators for
positioning the auger and hopper assembly 102. In embodiments, the actuators
are powered by a
12 VDC power supply. The power supply provides power for a hydraulic pump. In
embodiments, the hopper power supply is not in communication with the main
electrical power.
In embodiments, the battery powering the auger and hopper control system is
charged by the
main power supply when the main power is on. In an embodiment, the actuators
include one or
more electrical motors and associated linkages, where the motors provide
hydraulic power to
drive the hydraulic cylinders 5 (Figure 4 and Figure 5) and linkages with
sufficient force for
positioning the auger/hopper into a designated position and/or orientation. In
Figure 5, the
cylinder 5 is in a retracted configuration, whereas in Figure 4 the cylinder 5
is in an extended
configuration. Alternatively, the actuators arc hydraulically powered with
hydraulic fluid
pressurized by pumps that are powered by the 12 VDC power source.
100351 As indicated above, when setting up a hydraulic fracturing site it is
important to position
the sand delivery system and the blender so that the sand enters the blender
hopper 106 in
roughly the center of the hopper. However, it can be difficult to visualize
exactly where the
auger and hopper assembly 102 will be in the deployed position. Compounding
this problem is
that, in various embodiments, there are two blenders. One serves as a primary
blender, and the
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other serves as a back-up blender. The proppant feed _________________ the
chute on a sand conveyor belt, for
example ______________________________________________________________ needs
to be able to reach both blenders, while leaving some room between the
blenders for personnel and equipment, such as fluid hoses, chemical hoses, and
other tools.
[0036] Embodiments of the method and system described herein position the
blender system
100, lower the auger/hopper assembly 102, and align the hopper 106 with the
sand conveyer and
other sand equipment. The steps of aligning and positioning described herein
are performed
without power from the main power supply. In embodiments, the hydraulic lines
for powering
the auger/blender actuator are isolated from other hydraulic lines that
deliver hydraulic fluid to
different services or circuits, such as cooling fans, blower motors, chemical
pumps, the blender's
suction pump, valve actuators, and the auger motors for rotating the auger
blade. Optionally, the
hydraulic lines that power the auger/hopper actuator can share a same
hydraulic tank as other
hydraulic systems.
[0037] Referring now to Figure 4, shown in a side perspective view is a
portion of the auger and
hopper assembly 102. A start button 10 can selectively energize a motor that
drives a hydraulic
pump, where the pump pressurizes hydraulic fluid for powering the actuators.
Then the auger
and hopper assembly 102 can be raised or lowered using a three-position valve
12. The three-
position valve 12 can include positions for stowed, deployed, and closed.
In certain
embodiments, the stowed position can be labeled -up," and the deployed
position can be labeled
"down" on the valve 12. In the example of Figure 4, the valve 12 is disposed
in a hydraulic
circuit and between the hydraulic pump and the actuators. Shown in perspective
view in Figure
6 is an example of a hydraulic pump 14 for pressurizing the hydraulic fluid
used to actuate
cylinder 5 (Figure 5) into an extended position for selectively positioning
the auger and hopper
assembly 102. Further illustrated in Figure 6 is a battery 16 that selectively
provides electrical
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power to a motor 18 shown schematically coupled with the pump 14. The motor 18
and pump
14 are provided in a single unit in certain embodiments. Figure 7 provides
another view of this
unit. Electrical connections 15 are provided to connect the motor 18 to the
battery 16. Hydraulic
connections 19 to the pump 14 are provided as well.
100381 The present invention 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 invention 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 invention
disclosed herein and the
scope of the appended claims.
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