Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 02957166 2017-02-06
IN-LINE WELL FLUID EDUCTION BLENDING
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of, and claims priority to and the
benefit of co-pending
U.S. Provisional Application Serial No. 62,294,708 filed February 12, 2016.
BACKGROUND OF THE INVENTION
1. Field of Invention
[0002] The present disclosure relates in general to injecting fluid into a
well, and in particular to
methods and devices that blend additives to the fluid in an eductor.
2. Description of Prior Art
[0003] Fluids are often injected into wells during various wellbore
operations, such as during
drilling, pump down procedures, or hydraulic fracturing ("fracing"). A blender
is typically
provided at the well site during the fracing process for mixing chemicals,
water, and proppant.
The chemicals generally include friction reducers and viscosity enhancers. The
blender feeds the
mixture to high pressure pumps for pressuring the mixture to pressures that
often approach
10,000 psi; the pressurized mixture is then injected into the well to create
fractures.
[0004] Completion of a well typically involves perforating through casing that
lines the
wellbore, where perforating generally starts at a lowermost depth in the
wellbore, and is
sequentially performed at reduced depths up the wellbore. Plugs are generally
installed in the
wellbore above each set of perforations. It is not uncommon for an operator to
create twenty or
more sets of perforations, and install twenty or more plugs in a well. The
plugs are usually
-2-
CA 02957166 2017-02-06
removed with a drilling system. High pressure completion drilling fluid is
often circulated
through the wellbore while the plugs are being drilled. Typical drilling
pressures are in the range
of 2500 to 5000 psi, and the flow rates are usually at least 100 gpm (gallons
per minute). The
fluid flow rate and pressure is controlled so that the drilled plug fragments
flow out of the
wellbore entrained within the completion drilling fluid. To enhance the flow
of the completion
drilling fluid, friction reducers, chemicals, or viscosifiers such as liquid
gelling agents are added
to the well fluid in a blender. The friction reducers and viscosifiers are
normally polymers.
After a designated viscosity has been reached, the drilling fluid is directed
from the blender to
the high pressure pumps. Blending can be time consuming, which adds to the
total time to drill
out the wells containing the temporary frac plugs.
100051 Mixing devices and systems such as low, or zero, pressure surface
blending systems, low
pressure batch mixing systems, low pressure surface hydration systems and
other such systems
primarily depend on time. Conventional blenders use atmospheric tanks, static
mixers, internal
stirring paddles, and/or some form of non-positive suction and/or displacement
high pressure
jetting. The blending unravels and shear stresses component molecules of the
chemicals being
introduced. Blending is done in efforts to bring multiple components
ultimately into one
homogeneous and consistent blend of quality product with enhanced chemical and
physical
characteristics. Atmospheric blending generally requires at least two hours to
achieve hydration
rates of around 90%.
-3-
CA 02957166 2017-02-06
. .
SUMMARY OF THE INVENTION
[0006] Disclosed herein is an example method of wellbore operations that
includes providing an
eductor unit having a housing, an axial bore in the housing, a jet nozzle in
the bore, the jet nozzle
having an inlet and an outlet, and an inner diameter that reduces with
distance away from the
inlet. An annular space is formed between an outer surface of the jet nozzle
and inner surface of
the axial bore, an eductor port is adjacent the annular space that extends
through the housing, and
a profile is on an inner surface of the housing adjacent the outlet of the jet
nozzle and that defines
a venture. The method includes directing a flow of fluid into the inlet of the
jet nozzle, so that
the fluid flow exits the outlet of the jet nozzle and generate a low pressure
zone in the annular
space, and forming a mixture by providing communication between an additive
and the port, so
that the additive is drawn into the annular space and combines with the fluid.
In an example, the
method further includes directing the mixture into a wellbore to wash plug
cuttings from the
wellbore. The method optionally further includes directing the mixture through
a drill string, so
that the mixture discharges from a drill bit on an end of the drill string.
Further in this example,
the drill string can be coiled tubing or jointed pipe tubulars. In an
alternative, multiple eductor
ports are included. In an embodiment, the method further includes directing
different additives
through different eductor ports. In one alternative, the additive is
controllingly dosed through the
eductor port. An example exists where some of the fluid is bypassed around the
jet nozzle. By
monitoring a viscosity of the mixture, an amount of the additive combined with
the fluid can be
regulated based on a monitored value of the viscosity.
[0007] Also disclosed herein is a system for use in wellbore operations that
includes an upstream
line in communication with a source of a wellbore treatment fluid, a
downstream line in
communication with the wellbore, and an eductor unit. In this example the
eductor unit is made
-4-
CA 02957166 2017-02-06
up of a housing, an inlet in communication with the upstream line, an exit in
communication
with the downstream line, a jet nozzle in the housing that defines an annular
space between the
jet nozzle and an inner surface of the housing, and a port that extends
through a sidewall of the
housing adjacent the annular space, and that is in selective communication
with a source of
additive, so that additive drawn into the annular space mixes with the well
treatment fluid in the
housing to form a mixture. The system can further include a plurality of ports
that are each in
communication with different sources of additive. The system can optionally
include a control
valve for regulating a flow of additive to the eductor unit. A profile can
optionally be included
in a portion of the housing downstream from the jet nozzle, wherein the
profile defines a venturi.
Examples exist where the additive and wellbore treatment fluid are combined in
the eductor unit
to form a mixture. Alternatives exist where a sensor is included that is in
contact with the
mixture, and where the sensor senses a viscosity of the mixture, or where an
external sensor that
is not in direct contact with the mixture senses the flow rate of the additive
being pulled into the
mixture inside the eductor unit. Pumps can optionally be included in the
downstream line that
pressurize the mixture. In an alternative, a mixing device is in the
downstream line that is
between the pumps and the wellbore.
-5-
CA 02957166 2017-02-06
BRIEF DESCRIPTION OF DRAWINGS
[0008] 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:
[0009] Figure 1 is a side partial sectional view of an example of a plug
removal system for use
with a wellbore.
[0010] Figure 2 is a schematic view of an example of an eductor unit for use
with the plug
removal system of Figure 1.
[0011] Figures 2A and 3 are schematic views of alternate examples of eductor
units for use with
the plug removal system of Figure 1.
[0012] While the invention will be described in connection with the preferred
embodiments, it
will be understood that it is not intended to limit the invention 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 invention as defined by the
appended claims.
-6-
CA 02957166 2017-02-06
DETAILED DESCRIPTION OF INVENTION
[0013] 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
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.
[0014] 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.
[0015] Figure 1 shows in a side partial sectional view one example of a plug
removal system 10
for removing plugs 121, 122, 123 shown disposed within a wellbore 14. Wellbore
14 intersects a
subterranean formation 16, and is shown having a vertical portion V. and a
horizontal portion H.
As shown, plug 121 is in the vertical portion V, whereas plugs 122, 123 are in
the horizontal
portion H of wellbore 14. Perforations 18 are shown projecting radially
outward from wellbore
14 and into formation 16 which provide a pathway for connate fluid within
formation 16 to flow
into wellbore 14. Optionally, formation fractures (not shown) may be included
within formation
-7-
CA 02957166 2017-02-06
16 that were hydraulically generated by pressurizing wellbore 14, such as with
a fracturing fluid.
Plug removal system 10 is shown having a drill bit 20 disposed in wellbore 14
and being lowered
towards plug 121 for drilling out and removing plug 121. In the example, plugs
121-123 can be
formed from any material used in plugging or pressure isolating portions of
the wellbore 14, such
as but not limited to various types of composites and elastomers. Drill bit 20
is mounted on an
end of coiled tubing 22 (or other drilling tubular), where the bit 20 and
tubing define a drill string
23. Optionally included with the drill string 23 is a mud motor 24 that
attaches between the end
of the coiled tubing 22 (or other drilling tubular) and bit 20. Carrying tools
25 may alternatively
be included that are shown mounted on the string 23 upstream of the mud motor
24. Mud motor
24 rotates the bit 20 dovvnhole so that bit 20 can excavate through the plugs
121-123. Alternative
devices on surface may rotate the drill string 23 eliminating the need of the
mud motor 24. A
reel 26 is shown on surface for storing the coiled tubing 22; in coiled tubing
operations
unwinding tubing 22 from reel 26 deploys bit 20 deeper within wellbore 14.
Optionally, an oil
rig 28 is shown provided over the opening of wellbore 14 on surface, and from
which sections of
drill pipe may be used in place of the tubing 22. In an alternative, a blowout
preventer ("BOP")
30 is provided on surface and at the opening of wellbore 14 for providing
positive well control
during operations within wellbore 14.
100161 In one embodiment, the bit 20 includes nozzles that discharge a mixture
M of completion
drilling fluid. After the mixture M is discharged from bit 20, fragments of
the drilled plugs 121-
123 become entrained in the mixture M. The pressure of the mixture M exiting
the bit 20 is
sufficient to circulate the completion drilling fluid up the wellbore 14,
through BOP 30, and into
a return line 32. In the return line 32, the mixture M with fragments is
directed to a solids
removal system 34 for processing to remove particulate matter and solids
within the mixture M,
-8-
CA 02957166 2017-02-06
such as the cuttings from drilling though the plugs 121-123. A pressure
control valve 36 is shown
installed in return line 32 for maintaining a back pressure against pressure
in wellbore 14,
formation 16, and in return line 32. Removing the solids and particulate
matter from the
completion drill fluid forms a conditioned well fluid defined as fluid F. A
storage tank 38, via
line 40, receives fluid F discharged from solid removal system 34.
[0017] Still referring to Figure 1, as described below fluid F mixes with an
additive A to form
mixture M. In one example fluid F is made up substantially by weight of fresh
water and/or
brine water, and can contain trace amounts (i.e. less than 1.0 percent by
weight) of other
substances, including but not limited to particles of plug cuttings, and trace
amounts of additive
A not removed in the solids removal system 34. In the illustrated example,
additive A is stored
within an additive storage vessel 42 and is directed to an eductor unit 44 via
line 46. An optional
control valve 47 regulates flow of the additive through line 46. In a non-
limiting example,
regulating flow through line 46 includes allowing an unimpeded flow of
additive in line 46 (i.e.
100% of a maximum flow), fully impeding a flow of fluid in line 46 (i.e. 0% of
a maximum
flow), and partially impeding flow in line 46 so that a flow rate in line 46
is between 0% and
100% of a maximum flow. Fluid F is directed to eductor unit 44 within line 48,
whose opposing
ends are shown connected to tank 38 and eductor unit 44. An optional in-line
filtration device or
centrifugal sand/debris separator Z is shown placed in line 48 and between the
fluid storage tank
38 and eductor unit 44 to polish and finish the debris removal process of the
completion drilling
fluid F prior to being reintroduced in the wellbore operations. Line 46 is
schematically shown
coupled to an eduction port 49 that projects through a sidewall of eductor
unit 44. Additive A
exits line 46, flows through inject port 49, and into eductor unit 44 for
mixing with the fluid F. It
should be pointed out that embodiments exist wherein more than one type of
additive A is mixed
-9-
CA 02957166 2017-02-06
with the fluid F within eductor unit 44. Thus multiple additive storage
vessels 42, or multiple
compartments within additive storage vessel 42, may be provided for storing of
different
additives A to be mixed with fluid F. Further optionally, embodiments exist
wherein eductor
unit 44 includes multiple eduction ports 49, or where multiple additives are
injected into a
manifold (not shown) that is in communication with a single port 49. Examples
of additives
include friction reducers, viscosifiers (such as polyacrylamide and
polysaccharide), potassium
chloride, Xantham gum polymer, hydroxyethyl cellulose polymer, guar gum
polymer, biocides,
lubricants, long chain polymer molecules, ethylene glycol, methanol, isooctyl
alcohol, xylene,
ethylbenzene,kerosene, dihydroxyaluminum stearate, fatty acids,
poly(acrylamide-co-sodium
acrylate, ammonium bisulfite, isopropanol, 3-(tridecyloxy)-2-
hydroxypropyltrimethyl
ammonium, 1-dodecanesulfonic acid, hydroxyl-sodium salt, dodecene-l-sulfonic
acid,
glutaraldehyde, 2-propenoic acid, polymer with 2-propenamide, sodium chloride,
C12-C14
isoalkanes, and the like, and combinations thereof. Additives can be obtained
from Rockwater
Energy Solutions, 515 Post Oak Boulevard, Suite 200, Houston, Texas 77027, 713-
235-9500.
100181 In the example of Figure 1, mixture M exits eductor unit 44 and is
directed to a transport
pump 50 via line 52. In one example transport pump 50 is a centrifugal pump,
and discharges
the mixture M into line 54 at a pressure sufficient to overcome dynamic losses
in lines 48, 52,
54, which in an example is around 40 pounds per square inch ("psi") to around
100 psi. Mixture
M discharged from the transport pump 50 is directed to an injection pump 56
within line 54.
Examples of the injection pump 56 include a high pressure positive
displacement pump that
pressurizes the mixture M up to about 10,000 psi. Optionally, mixture M after
being discharged
from injection pump 56 is directed to a high pressure mixing device 58 via
line 60. One example
of a high pressure mixing device 58 is provided in U.S. Patent Application No.
14/075,436 filed
-10-
CA 02957166 2017-02-06
,
,
November 8, 2013, which is assigned to the owner of this application, and
which is incorporated
by reference herein in its entirety for all purposes. An advantage of the high
pressure mixing
device 58 installed between lines 60 and 62 is that the need for surface
atmospheric, or other
such low pressure mixing devices is eliminated, thereby allowing for real time
positive
displacement homogenous mixing and blending. Another advantage of the device
38 is near
instantaneous full hydration of additive polymers under pressure while mixture
M is heading
towards the drill string 23, and ultimately exiting the bit 20. A feedline 62
is shown having an
end attached to a discharge of mixing device 58 and which provides fluid
communication
between mixing device and coiled tubing 22 wound on reel 26. Thus in an
example, the mixture
M is injected into the well 14, via coiled tubing 22 (or other drilling
tubular) and used for
removing cuttings or other particulate matter when drilling through the plugs
121-123.
100191 Referring now to Figure 2, shown in schematic view is an example of the
eductor unit 44,
where bypass lines 63, 64 divert a portion of the fluid F entering eductor
unit 44. As shown,
lines 63, 64 each have an inlet end connected to line 48, and an exit end
connected to line 52.
Also shown are leads 651-653 which have inlets connected to line 46, and leads
654-656, which
have inlets connected to line 66. In the illustrated example, line 66 branches
from line 46 so that
additive flowing in line 46 can be delivered to 654-656. Leads 651-656
respectively register with
ports 671-676 that extend through a sidewall of a housing 68. Housing 68 is an
annular member
shown provided generally coaxially in the eductor unit 44, and that extends
from where bypass
lines 63, 64 intersect line 48 to where bypass lines 63, 64 intersect line 52.
Thus in the example
of Figure 2, bypass lines 63, 64 carry an amount of fluid F around housing 68.
A bore 70 is
shown extending axially through housing 68 thereby providing fluid
communication between
line 48 and line 52. A jet nozzle 71 is disposed within housing 68 having a
passage 72 extending
-11-
CA 02957166 2017-02-06
axially through the jet nozzle 71. An inlet 73 to the passage 72 is shown
disposed in a portion of
housing 68 proximate to line 48, and which receives a portion of the flow of
fluid F from line 48
not diverted to bypasses 63, 64. Fluid F entering jet nozzle 71 through the
inlet 73, flows
through the passage 72 and exits through an outlet 74 shown on an end of
nozzle 71 distal from
inlet 73. In the example of Figure 2, outlet 74 of jet nozzle 71 has a cross-
sectional area that is
smaller than or equal to a cross-sectional area of the inlet 73 to jet nozzle
71. In one
embodiment, the outlet 74 of jet nozzle 71 has a cross-sectional area that is
greater than the
cross-sectional areas of bypass lines 63, 64. Bypass lines 63, 64 can have the
same or different
cross sectional areas. Examples exist wherein bypasses 63 and 64 are operable
bypasses, and
depending on desired flow through jet nozzle 71, may either fully open or
closed on demand
with various types of flow control devices (not shown), such as but not
limited to, ball valves.
[0020] A profile 75 is shown that extends axially along a portion of the
sidewalls of bore 70 and
proximate the outlet 74 of jet nozzle 71. An inner surface of profile 75
follows a path that is
generally oblique to an axis Ax of bore 70 and radially inward from sidewalls
of bore 70. At an
axial distance downstream from outlet 74, the inner surface of profile 75
transitions radially
outward towards sidewalls of bore 70 and along a path oblique to axis Ax. At
the transition the
profile 75 has a maximum radial thickness, which forms a minimum diameter D.
within bore
70. An angle between the surface of profile 70 and axis Ax downstream of
transition is greater
than an angle between surface of profile 70 and axis Ax upstream of
transition. The profile 75
thus reduces flow path diameter in the bore 70 from a maximum diameter DB to
minimum
diameter Dmin, and back to maximum diameter DB. The changes in diameter of the
bore 70
define a venturi 76 within bore 70. As such, the restricted diameter of the
venturi 76 causes a
localized increase in velocity of the fluid F flowing within bore 70, which in
turn generates a
-12-
CA 02957166 2017-02-06
localized reduced pressure. An annular space 77 shown between the sidewalls of
bore 70 and
outer radius of jet nozzle 71 also experiences a localized reduced pressure.
Reducing the
pressure in the annular space 77 creates a pressure differential between the
annular space 77 and
line 46, which induces a flow of additive A through ports 671-676 into annular
space 77.
100211 Shown in Figure 2A is an alternate example of eductor unit 44A, where
additive flowing
through each of the ports 671-676 can be different, which is unlike the
embodiment of Figure 2
wherein the additive in each port 671-676 is the same. In the embodiment of
Figure 2A,
dedicated lines 46A1-46A6 have inlet ends coupled with storage vessels 42A1-
42A6, and outlet
ends that register respectively with ports 671-676. Control valves 47A1-47A6
are shown
respectively on lines 46A1-46A6 and that regulate flow through the lines 46A1-
46A6. Thus
depending on a particular application, a same or different additive is
injected into the eductor
unit 44, 44A. Examples exist wherein valving (not shown) is installed that
allow for selective
changing between injecting the same or different additives. Further, in one
example, the lines
46A1-46A6 connecting to each of the ports 671-676 can include control valves
(not shown) for
regulating the volumetric flow rate of additives through the eduction ports
671-676-
[0022] The feedback for determining the flow through lines 46, 48 (Figure 2)
can be gained from
monitoring conditions of the mixture M downstream of eductor unit 44, or at
the discharge end
of eductor unit 44. For example, if a viscous fluid makes up one of the
additives A being
injected via eduction ports 671-676, monitoring the viscosity of the mixture M
real time can
provide a basis for adjusting a flow rate of the viscous fluid additive. An
example of a
monitoring system is shown with an indicator 78 mounted on a probe 80 that is
in
communication with the mixture M in line 62. Probe 80 includes sensing means
that monitors
information about the fluid, such as but not limited to fluid conditions,
characteristics, and/or
-13-
CA 02957166 2017-02-06
properties. Signals representing the sensed fluid information is transmitted
to a controller 82 via
a communication means 84. In an example, controller 82 includes an information
handling
system, which contains a processor, memory accessible by the processor,
nonvolatile storage
area accessible by the processor, and logics for performing each of the steps
above described.
Examples exist where communication means 84 includes an electrically
conducting medium,
means for wireless communication, fiber optics, and combinations thereof. In
one non-limiting
example of operation, logics direct controller 82 to change an amount of
additive being
dispensed to the eductor unit 44 based on fluid information sensed by the
monitoring system. In
an embodiment, controller 82 provides instructional commands to control valve
47 (Figure 2), or
control valves 47A1-47A6 (Figure 2) to regulate the amount of additive being
dispensed to
eductor units 44, 44A. In an example, changing the amount of additive includes
reducing a flow
rate of the amount of additive, or increasing a flow rate of the amount of
additive. Conversely,
an external electronic digital monitoring sensor and electronic readout (not
shown) that senses
the flow rate of additive A through line 46, but that is not in direct contact
with additive A or
mixture M, can be mounted on additive storage vessel 42 or on line 46.
Alternatively the sensor
can monitor an internal drainage rate of the additive storage vessel 47. In
this example, a
volumetric versus timed dosage flow rate of additive A can be released into
the eductor via line
46 in a controlled dosage fashion using control valve 47, the electronic
readout and operation of
control valve 47 can either be hands on or remotely controlled via
electronics.
100231 One of the advantages of the mixing of the additive A and fluid F
within the eductor unit
44 is that particular additives can be controllingly dosed into the stream of
fluid F flowing within
the eductor unit 44. In certain embodiments when used in conjunction with the
high pressure
mixing device 58, completion drilling fluid additives are homogenously mixed,
blended and the
-14-
CA 02957166 2017-02-06
polymers hydrated near instantaneously. An example of near instantaneously is
from about 10
seconds to about 15 seconds or less. One non-limiting example of hydration is
defined by the
absorption of water into the polymeric molecule, or cleavage of water into the
polymeric
molecule; thus embodiments exist where the greater the absorption, the higher
the yield of the
polymer. In contrast, traditional ways of hydrating particular polymers may
require multiple
hours of blending, mixing, and shear stressing. The additive A is added to the
fluid F over a
period of time when forming the mixture M in the eductor unit 44; thus the
flowrate of additive
A into the eductor unit 44 is less than that of the known method of dumping
all of the additive
into a mixing vat. The reduced flow rate of the additive of the present
disclosure is believed to
be due to efficiency of hydration percentage when used in conjunction with the
high pressure
inline mixer 58. Accordingly, as described above and illustrated in the
figures, combining the
additive A with fluid F in the confines of the eductor unit 44, and used in
conjunction with the
high pressure inline mixer 58, increases initial contact surface area between
the additive A and
fluid F, thereby significantly and unexpectedly increasing the rate of
hydration over previously
known methods.
[0024] In one alternative, the percent hydration of the additives A in the
fluid F is estimated by
measuring viscosity of the mixture M, and correlating the measured viscosity
with a value of
hydration. Example methods of measuring hydration rates of additive A verses
percentage of
polymer by volume of mixture M include using field hand held devices, one of
which is a marsh
funnel viscosity measurement devices or viscometers, such as the Viscolite
700, manufactured
by Hydramotion, which measures the dynamic viscosity in centipoise.
Information on the
Viscolite 700 can be obtained from Nelson Systems, sys.nelsontech.com. A non-
limiting
example of hydration rates achieved within the high pressure inline mixer 58
when utilizing the
-15-
CA 02957166 2017-02-06
,
,
eductor unit 44 include up to about 98% hydration, 96 % hydration, 92 %
hydration, 90%
hydration, 88% hydration, 86% hydration, and all values between these listed
values. In one
embodiment, 100% hydration occurs when the molecules making up the additive
being hydrated
have become fully associated, or cleaved, with an amount of water molecules
such that the
molecules making up the additive being hydrated cannot become associated with
any more or
any additional water molecules. Not only is there a tremendous time savings
with the eductor
unit 44, but capital costs can be significantly reduced as blender units are
significantly more
expensive than the piping and hardware of an example of the eductor unit 44.
100251 Figure 3 shows in a side partial sectional view an alternate example of
an eductor unit
44B and having bypasses 63B, 64B which direct some of the fluid F being
introduced via line
46B to make its way directly to line 52B. This diverts some of the fluid F
around the housing
68B of eductor unit 44B. In the example of Figure 3, a single port 49B is
shown for delivering
additive A into annular space 77B for mixing with fluid F to create mixture M.
Additive A is
shown being stored within a hopper 86B, and dispensed from hopper 86B into a
conduit 87B by
selectively operating an on/off valve 88B shown mounted within conduit 87B. An
end of
conduit 87B opposite from its connection to hopper 86B registers with port 67B
that is formed
through a sidewall of housing 68B. A control valve 90B is shown in conduit 87B
and on a side
of valve 88B distal from hopper 86B. However, examples exist wherein control
valve 90B is
disposed between valve 88B and hopper 86B. In the embodiment of Figure 3, when
valve 88B is
in the open position, control valve 90B regulates a flow of additive A from
hopper 86B and into
annular space 77B. Monitoring the level of additive A within hopper 86B over
time, and
comparing the changing level with metered marks provided on the wall of the
hopper 86B , a
flow rate of the additive A into the annular space 77B can be estimated. If
the observed flow rate
-16-
CA 02957166 2017-02-06
,
of additive A is different from a designated flowrate of additive A, the
control valve 90B can be
adjusted so that the designated flowrate of additive A is delivered to the
annular space 77B. In
one example, the designated flowrate of additive A is so that mixture M has a
particular amount
of additive A being mixed with fluid F to achieve designated properties of the
mixture M. In one
example, control valve 90B is a diaphragm-type pinch valve whose opening can
be adjusted with
a hand wheel manually, which can be obtained from Red Valve, www.redvalve.com,
Red Valve
Company 600 N. Bell Ave., Bldg. 2, Carnegie, PA 15106.
100261 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. For
example, the embodiments of Figures 2, 2A, and 3 can be combined, either in
series or in parallel
to form a system for introducing additives into a fluid to be injected into a
wellbore. 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.
-17-
