U.S. patent application number 13/823181 was filed with the patent office on 2013-10-24 for downhole delivery of chemicals with a micro-tubing system.
This patent application is currently assigned to SCHLUMBERGER TECHNOLOGY CORPORATION. The applicant listed for this patent is Richard D. Hutchins, Yan P. Kuhn de Chizelle, Hemant K.J. Ladva, Andrey Mirakyan, Douglas Pipchuk, Mathew M. Samuel, Don Williamson. Invention is credited to Richard D. Hutchins, Yan P. Kuhn de Chizelle, Hemant K.J. Ladva, Andrey Mirakyan, Douglas Pipchuk, Mathew M. Samuel, Don Williamson.
Application Number | 20130277047 13/823181 |
Document ID | / |
Family ID | 45833539 |
Filed Date | 2013-10-24 |
United States Patent
Application |
20130277047 |
Kind Code |
A1 |
Kuhn de Chizelle; Yan P. ;
et al. |
October 24, 2013 |
Downhole Delivery Of Chemicals With A Micro-Tubing System
Abstract
A technique utilizes micro-tubing to facilitate performance of a
well treatment in which the micro-tubing is deployed for
cooperation with a larger tubing, such as a coiled tubing
positioned in wellbore. The micro-tubing is used to deliver a
separated chemical downhole to modify a property of a treatment
fluid used in performing a desired well treatment operation at a
desired treatment region along the wellbore. A variety of
additional components may be combined with the micro-tubing to
further facilitate the treatment application.
Inventors: |
Kuhn de Chizelle; Yan P.;
(Houston, TX) ; Samuel; Mathew M.; (Sugar Land,
TX) ; Pipchuk; Douglas; (La Defanse Cedex, FR)
; Williamson; Don; (Belding, MI) ; Mirakyan;
Andrey; (Katy, TX) ; Ladva; Hemant K.J.;
(Missouri City, TX) ; Hutchins; Richard D.; (Sugar
Land, TX) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Kuhn de Chizelle; Yan P.
Samuel; Mathew M.
Pipchuk; Douglas
Williamson; Don
Mirakyan; Andrey
Ladva; Hemant K.J.
Hutchins; Richard D. |
Houston
Sugar Land
La Defanse Cedex
Belding
Katy
Missouri City
Sugar Land |
TX
TX
MI
TX
TX
TX |
US
US
FR
US
US
US
US |
|
|
Assignee: |
SCHLUMBERGER TECHNOLOGY
CORPORATION
Sugar Land
TX
|
Family ID: |
45833539 |
Appl. No.: |
13/823181 |
Filed: |
September 15, 2011 |
PCT Filed: |
September 15, 2011 |
PCT NO: |
PCT/US11/51689 |
371 Date: |
July 9, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61384011 |
Sep 17, 2010 |
|
|
|
Current U.S.
Class: |
166/250.12 ;
166/242.2; 166/250.01; 166/299; 166/305.1 |
Current CPC
Class: |
E21B 17/203
20130101 |
Class at
Publication: |
166/250.12 ;
166/305.1; 166/299; 166/250.01; 166/242.2 |
International
Class: |
E21B 17/20 20060101
E21B017/20 |
Claims
1. A method of performing a well treatment, comprising: routing a
micro-tubing down through a coiled tubing deployed in wellbore;
employing a securing mechanism to secure a lower end of the
micro-tubing proximate a discharge region of the coiled tubing;
positioning a communication line within the micro-tubing; and
delivering treatment fluids downhole through the micro-tubing and
through an interior of the coiled tubing located between the
micro-tubing and an interior surface of the coiled tubing, the
treatment fluids being dissimilar.
2. The method as recited in claim 1, wherein routing comprises
pumping the micro-tubing down through the coiled tubing via a
velocity booster coupled to a lead end fixture of the
micro-tubing.
3. The method as recited in claim 1, wherein positioning comprises
positioning a fiber optic communication line within the
micro-tubing.
4. The method as recited in claim 1, wherein delivering comprises
delivering a treatment fluid through the micro-tubing which alters
the properties of the overall well treatment.
5. The method as recited in claim 1, wherein routing comprises
routing a plurality of micro-tubings down through the coiled
tubing.
6. The method as recited in claim 1, further comprising
distributing treatment fluid from the micro-tubing, through a
plurality of perforations, and into a mixing region for mixing with
dissimilar treatment fluid delivered through the interior of the
coiled tubing between the micro-tubing and the interior surface of
the coiled tubing.
7. The method as recited in claim 1, further comprising providing a
sensor system downhole coupled to the communication line.
8. The method as recited in claim 1, further comprising utilizing
the communication line to power a downhole tool.
9. The method as recited in claim 2, wherein pumping comprises
pumping down the micro-tubing with a pump-down plug having at least
one burst disc which may be ruptured to enable delivery of at least
one type of fluid.
10. The method as recited in claim 1, further comprising coupling
the micro-tubing and the communication line to a retrievable
delivery and electronics package.
11. The method as recited in claim 1, further comprising attaching
a canister containing an additional treatment fluid to an end of
the micro-tubing and controlling delivery of the additional
treatment fluid with a valve.
12. A method of performing a well treatment, comprising: deploying
a micro-coil tubing and a larger tubing downhole to a well
treatment region of a wellbore; delivering a treatment fluid
downhole through the larger tubing; using the micro-coil tubing to
deliver a chemical downhole for combination with the treatment
fluid at the well treatment region, the chemical being selected to
modify a property of the treatment fluid; and communicating signals
along the larger tubing via a communication line.
13. The method as recited in claim 12, wherein deploying comprises
deploying the larger tubing in the form of coiled tubing.
14. The method as recited in claim 12, wherein deploying comprises
pumping the micro-coil tubing down through an interior of the
larger tubing.
15. The method as recited in claim 12, wherein deploying comprises
deploying the micro-coil tubing along an exterior of the larger
tubing.
16. The method as recited in claim 12, further comprising routing
the communication line downhole through the micro-coil tubing.
17. The method as recited in claim 12, further comprising forming
the micro-coil tubing from a thermoplastic material.
18. The method as recited in claim 12, wherein using comprises
delivering the chemical downhole through the micro-coil tubing in
the form of an additive comprising one of: a crosslinker, a
breaker, an HT stabilizer, a corrosion inhibitor, a pH adjustor, a
rheology enhancer, or an enzyme.
19. The method as recited in claim 12, wherein using comprises
delivering the chemical downhole through the micro-coil tubing in
the form of a tracer for monitoring the well and the well
treatment.
20. The method as recited in claim 12, wherein using comprises
delivering the chemical downhole into a mixing region with a
desired turbulent flow pattern.
21. The method as recited in claim 12, further comprising detecting
electrical properties of a surrounding formation by using
conductive and nonconductive portions of the micro-coil tubing.
22. A system for treating a well, comprising: a coiled tubing
deployed in a wellbore; a micro-tubing sized to enable deployment
along an interior of the coiled tubing; a securing mechanism to
secure a downhole end of the micro-tubing proximate an end of the
coiled tubing; and an end fixture coupled to the micro-tubing and
located downhole to control the discharge and mixing of chemicals
separately delivered downhole through the coiled tubing and the
micro-tubing to modify a well treatment.
23. The system as recited in claim 22, wherein the micro-tubing is
a non-metallic tubing deployed in the coiled tubing and held by the
securing mechanism.
24. The system as recited in claim 22, wherein the end fixture
comprises a plurality of openings located at positions 360.degree.
around a mixing chamber.
25. The system as recited in claim 22, wherein the end fixture
comprises a plurality of vanes oriented to facilitate mixing of a
chemical additive, delivered through the micro-tubing, with a
separate well treatment fluid delivered through the coiled tubing.
Description
BACKGROUND
[0001] During and after many downhole wellbore operations, such as
hydraulic fracturing, a controlled release of chemicals may be
desired. In many applications, however, treatment fluids travel to
substantial depths which can affect properties of the chemicals
delivered downhole. The detrimental effects on the treatment
chemicals often are exacerbated when certain chemicals are mixed at
the surface and then delivered downhole to the substantial
depths.
[0002] Coiled tubing has been employed to deliver well treatment
fluids downhole for enhancing hydrocarbon production. Examples of
well treatment applications employing coiled tubing include the
pumping of stimulation fluids, e.g. acids, solvent washes, scale
dissolvers, and/or fracturing fluids; and the pumping of cleanout
fluids, e.g. nitrogen, CO2, polymer-containing aqueous brines
(xanthan and diutan), and mixed metal hydroxides to lift sand,
debris or drill cuttings. However, challenges have arisen in
delivering the chemicals in a controlled manner to the desired
depths with conventional coiled tubing systems. A number of
solutions have been proposed, such as the use of fluid plugs,
canisters, and encapsulation. Additionally, the use of micro-coil
chemical delivery has been attempted, but such techniques incur
various difficulties.
[0003] For example, difficulties arise in retrofitting existing
coiled tubing systems with micro-coil tubing. Additionally,
existing systems are inadequate for delivering and mixing the
desired chemicals to modify properties of the well treatment
system. Furthermore, existing systems may not be capable of
sufficient interaction with monitoring systems and other downhole
systems employed during a given well treatment application.
SUMMARY
[0004] In general, a system and method is described for
facilitating performance of a well treatment in which a
micro-tubing, e.g. a micro-coil or micro-capillary tubing, is
deployed for cooperation with a larger tubing, such as a coiled
tubing positioned in a wellbore. The micro-tubing is used to
deliver a separated chemical downhole for modifying a property of a
treatment fluid used in performing a desired well treatment
operation at a desired treatment region along the wellbore.
Additional components may be combined with the micro-tubing to
further facilitate the treatment application. For example, a
securing mechanism may be used to selectively secure a lower end of
the micro-tubing proximate a lower end of the larger tubing. In
some embodiments, a communication line also is routed downhole
along the micro-tubing to facilitate transmission of signals, e.g.
power and/or data, between downhole and surface locations. The
communication line may be used in cooperation with a sensor
system.
BRIEF DESCRIPTION OF THE DRAWINGS
[0005] Certain embodiments will hereafter be described with
reference to the accompanying drawings, wherein like reference
numerals denote like elements, and:
[0006] FIG. 1 is a schematic front elevation view of one embodiment
of a well system having a micro-tubing deployed in a wellbore for a
well treatment application;
[0007] FIG. 2 is a bottom view of the micro-tubing illustrated in
FIG. 1;
[0008] FIG. 3 is a front view of one embodiment of a treatment
system employing a micro-coil tubing having an end fixture;
[0009] FIG. 4 is a cross-sectional, schematic view of another
embodiment of a treatment system employing a micro-tubing having a
different type of end fixture used in cooperation with a larger
tubing;
[0010] FIG. 5 is a cross-sectional, schematic view of another
embodiment of a treatment system employing a micro-tubing used in
cooperation with a larger tubing;
[0011] FIG. 6 is a cross-sectional, schematic view of another
embodiment of a treatment system employing a micro-tubing used in
cooperation with a larger tubing; and
[0012] FIG. 7 is a schematic view of another embodiment of a
treatment system employing a micro-tubing used in cooperation with
a larger tubing.
DETAILED DESCRIPTION
[0013] In the following description, numerous details are set forth
to provide an understanding of the present disclosure. However, it
will be understood by those of ordinary skill in the art that the
present disclosure may be practiced without these details and that
numerous variations or modifications from the described embodiments
may be possible.
[0014] The embodiments described herein generally relate to a
system and method for improving the performance of a well treatment
at a downhole location. According to one embodiment, a treatment
fluid, e.g. a fracturing fluid, stimulation fluid, or other
treatment fluid, may be modified by separately delivering one or
more chemicals downhole through a micro-tubing. By way of example,
the micro-tubing may comprise a micro-coil tubing which is pumpable
along a larger tubing, e.g. a larger coiled tubing, deployed in a
wellbore. In some applications, the micro-tubing is pumped down
through an interior of the larger tubing with the aid of a
pump-down plug and/or velocity booster.
[0015] The well treatment system also may comprise a communication
line for conveying sensor data which enables monitoring of the
treatment application. In some applications, the monitoring may be
performed in real-time by, for example, a fiber optic system
deployed downhole adjacent the micro-tubing. The communication line
may be protected by the micro-tubing via placement of the
communication line along an interior of the micro-tubing. Depending
on the application, the communication line may utilize an optical
fiber in the form of a distributed sensor (for sensing temperature,
vibration, and/or pressure) and/or the communication line may be
coupled to downhole sensor systems. Additionally, the communication
line may be an individual line or multiple lines for carrying data
signals and/or power signals between the downhole sensor or sensor
systems. If the communication line is designed for power, power
signals may be directed downhole to power one or more components of
the well treatment equipment located downhole.
[0016] According to one specific embodiment, the micro-tubing
employed with the overall well treatment system is a pumpable
tubing formed of a non-metallic material, such as a thermoplastic
material. One example of a suitable thermoplastic material is a
polyetheretherketone (PEEK) material which is delivered along an
interior of coiled tubing to an end of the coiled tubing via
pumping. A downhole end of the micro-tubing is fitted with an end
fixture in the form of a plug, e.g. an expandable or inflatable
plug. The plug may be designed as a securing mechanism to secure
the micro-tubing within the coiled tubing or casing and to seal the
micro-tubing with respect to the coiled tubing or casing. In an
embodiment, the micro-tubing may be formed from a composite
material containing metals or formed from a non-metallic material
comprising a coating of metallic paint or nano materials
[0017] As illustrated and described in greater detail below, one
embodiment of the plug is fitted with burst discs, such as a first
burst disc which enables inflation or expansion of the plug to
facilitate pumping of the micro-tubing, and another burst disc to
open the coil for flow of chemicals once the thermoplastic
micro-tubing has been fully inserted to the end of the surrounding
coiled tubing. In some embodiments, the plug is designed to fit
into a securing mechanism having the form of a tool receptacle
attached at the end of the coiled tubing. The tool receptacle helps
lock the micro-tubing in place. The securing mechanism also may be
integrated with a mixing device to facilitate mixing of fluids
delivered through the micro-tubing and through the coiled tubing.
By way of example, the mixing device may be designed with openings
oriented to create a vortex effect which facilitates mixing of
fluids, and thus modification of the treatment fluid at the
downhole location. The plug and/or other securing features enable
retrofitting of coiled tubing with a much smaller micro-tubing by
allowing deployment of the micro-tubing to a desired location
within the coiled tubing via pumping followed by securing the
micro-tubing.
[0018] Referring generally to FIG. 1, one embodiment of a well
system 20 is illustrated as having a well treatment system 22
deployed in a wellbore 24. The wellbore 24 extends down from a
surface location and into or through a subterranean formation 26.
By way of example, the wellbore 24 may be cased with a casing 28
having perforations 30 which allow injection of the treatment fluid
into the surrounding subterranean formation 26 at a desired well
treatment region 32.
[0019] The well treatment system 22 is illustrated schematically
and may comprise a variety of configurations and components. By way
of example, the well treatment system 22 comprises a micro-tubing
34, which may be a micro-coil tubing or a micro-capillary tubing,
for delivering an additive/chemical 35 to the well treatment region
32. The micro-tubing 34 is deployed along a larger tubing 36, which
in many applications comprises coiled tubing. In the example
illustrated, the micro-tubing 34 is deployed along an interior 38
of the larger tubing 36, e.g. coiled tubing. Depending on the
application, the micro-tubing 34 may comprise an individual tubing
or multiple tubings, as represented by the additional tubing shown
in dashed lines in FIG. 1. If the micro-tubing 34 comprises
multiple tubings, a plurality of different chemicals 35 may be
selectively delivered downhole to the well treatment region 32 via
the multiple tubings for mixing with a treatment fluid 39.
Treatment fluid 39 is delivered separately along the interior 38 of
larger tubing 36 outside of micro-tubing 34.
[0020] By way of example, the well treatment fluid 39, e.g. a
fracturing fluid, may be delivered downhole through tubing 36 in
the annulus formed between micro-tubing 34 and an interior surface
40 of tubing 36 before exiting at a discharge region 41 of tubing
36. One or more chemical additives 35 may be simultaneously, but
separately, delivered down through micro-tubing 34 for mixing with
treatment fluid 39 at a desired downhole mixing region 42, e.g. a
mixing chamber. This at depth mixing allows the well treatment
fluid to be modified in a desired manner at the downhole region 42
for injection into the well treatment region 32 of formation
26.
[0021] In the example illustrated, micro-tubing 34 is pumped down
through the interior of coiled tubing 36 which enables retrofitting
of existing coiled tubing systems. However, the micro-tubing 34 may
be pumped down through larger tubing in a variety of applications
and systems. The pumping down may be facilitated by providing the
micro-tubing 34 with an end fixture 44 which may comprise (or work
in cooperation with) a securing mechanism designed to secure
micro-tubing 34 at a desired position within coiled tubing 36, such
as at a downhole end of coiled tubing 36.
[0022] According to one embodiment, end fixture 44 comprises a
pump-down plug 46 having a seal 48 designed to seal against
interior surface 40 of tubing 36. The pump-down plug 46 helps pull
micro-tubing 34 down through the interior 38 of tubing 36 when
fluid is pumped down from a surface location. The plug 46 may be
selectively expanded or inflated against the interior surface 40 to
facilitate pumping of micro-tubing 34 to the desired downhole
location within larger tubing 36. In some applications, the
pump-down plug 46 serves as a securing mechanism via selective
expansion into engagement with the surrounding tubing 36. However,
in other applications a separate securing mechanism 50 may work
alone or in cooperation with plug 46 to secure the micro-tubing 34
at the desired location in tubing 36. For example, the securing
mechanism 50 may comprise a landing feature, latch, collett, or
other securing mechanism designed to grip and hold the lead end of
micro-tubing 34 at a desired location, e.g. at a downhole end of
tubing 36.
[0023] As further illustrated in FIG. 2, the pump-down plug 46 may
comprise one or more controllable openings 52, e.g. valves or burst
discs, which allow the plug 46 to be pressurized and inflated or
otherwise expanded against interior surface 40. In one example,
application of sufficient pressure causes the disc 52 to rupture
which enables flow of chemicals 35 down through micro-tubing 34 and
into mixing region 42. In some applications, an additional burst
disc or valve 52 may be used to prevent expansion of the pump-down
plug 46 until a desired stage of the process. Other burst discs or
valves 54 also may be used in plug 46 to selectively control the
flow of well treatment fluid 39 through the plug from the annulus
surrounding micro-tubing 34 within larger tubing 36. In other
embodiments, however, the flow of well treatment fluid 39 may be
enabled by deflating or otherwise disengaging pump-down plug 46
from interior surface 40.
[0024] In some applications, the communication line 56 of well
treatment system 22 comprises one or more communication lines, as
further illustrated in FIG. 1. The communication line 56 may
comprise an optical fiber cable, however the communication line
also may comprise other signal carriers to carry data signals
and/or electrical power signals. In some embodiments, communication
line 56 enables transmission of data signals to and/or from an
electronics and sensor system 58 deployed downhole to monitor the
mixing and application of treatment fluids and additives. By way of
example, sensor system 58 may comprise downhole sensors for
measuring fluid pH, pressure, temperature, viscosity, acoustic
measurements, salinity, and/or other parameters. The communication
line 56 also may comprise electric lines designed to transfer
electrical power signals to a downhole tool 60 of the downhole
equipment employed to carry out the well treatment operation. For
example, downhole tool 60 may comprise one or more components of an
injection system employed to inject fracturing fluids into the
surrounding formation 26. In some embodiments, downhole tool 60
comprises one or more of actuatable valves, sleeves, and/or ports.
A control system 62, such as a computer-based processing system,
may be employed at a surface location with suitable surface
equipment or at another suitable location to control the delivery
of signals downhole and to receive/process data received from the
downhole components.
[0025] In the embodiment illustrated, communication line 56 is
deployed within micro-tubing 34, although the communication line
may be routed downhole within the coiled tubing 36 outside of
micro-tubing 34 or at other suitable locations. In some
applications, the communication line 56 is embedded in a wall of
the micro-tubing 34 or in a wall of the larger tubing 36. By
placing the communication line 56 within micro-tubing 34, the
communication line is protected. Depending on the application, the
communication line 56 may be pumped down through tubing 36 while
within micro-tubing 34. In other applications, however, the
communication line 56 may be pumped down through micro-tubing 34
after deployment of the micro-tubing downhole. If the communication
line 56 is an optical fiber used as a distributed sensor system,
the optical fiber may simply be pumped down and returned to a
surface location, as with other distributed sensor systems deployed
downhole. In other applications, the communication line 56 is
coupled to downhole equipment, such as sensor system 58 and/or
downhole tool 60, via appropriate wet connectors or other types of
available connectors.
[0026] As discussed briefly above, some treatment applications
benefit from forming micro-tubing 34 from a thermoplastic material,
such as PEEK. Such materials have high temperature limits and high
tensile strength while being exceptionally chemically resistant. In
this specific example, the pump-down plug 46 is made of a plastic
or metal material with concentric seals 48 along its outside
diameter. The seals 48 serve as wipers and prevent undesirable
fluid communication across the plug. Pressurizing fluid above the
plug 46 causes the plug to expand and then to move downhole along
the interior of tubing 36 until it is received in securing
mechanism 50, e.g. a landing tool. In some applications, the plug
46 is designed to latch into a receptacle attached to the end of
the coiled tubing 36 so as to secure the lead end of the PEEK
tubing.
[0027] After landing in the securing mechanism 50, plug 46 may be
opened to the flow of additives/chemicals by opening the
controllable opening 52. The plug 46 also may be removed, e.g.
dissolved, or otherwise opened up to enable the flow of well
treatment fluid down through tubing 36 along the exterior of
micro-tubing 34. To remove micro-tubing 34 from the wellbore, the
tubing may simply be pulled from the plug 46 and from securing
mechanism 50, if present. After removal, the PEEK tubing 34 can be
retooled for the next deployment. Alternatively, the micro-tubing
34 may be left within larger tubing 36 and used for future delivery
of desired chemicals.
[0028] Referring generally to FIG. 3, another embodiment of end
fixture 44 is illustrated as located at the lower end of
micro-tubing 34. In this embodiment, the end fixture 44 comprises
one or more velocity boosters 64 designed to catch fluid as end
fixture 44 and micro-tubing 34 are pumped down through larger
tubing 36 to the securing mechanism 50. The velocity boosters 64
may be in the form of cups or flaps designed to catch the pump-down
fluid and to speed movement of micro-tubing 34 through the
surrounding tubing 36. In some applications, the pump-down fluid
may comprise a treatment fluid.
[0029] End fixture 44 further comprises an enlarged portion 66,
such as an enlarged cylinder, having a plurality of perforations
68. The perforations 68 are oriented to discharge the desired
chemical 35 delivered through micro-tubing 34 into mixing region
42. Initially, the perforations 68 may be sealed to protect against
leakage during deployment of the micro-tubing 34 through coiled
tubing 36. By way of example, the perforations may be sealed with a
dissolvable or removable material 70. Similarly, the velocity
booster or boosters 64 also may be dissolvable or removable. In
some applications, the velocity boosters 64 are frangible so they
can be selectively shattered and removed. Removal of the velocity
boosters 64 is often desirable to facilitate flow of well treatment
fluid through interior 38 of coiled tubing 36 for mixing with the
chemical additives 35 delivered through micro-tubing 34. In a
similar manner, the seals 48 and/or plug 46 illustrated in FIG. 1
also may be dissolvable or removable.
[0030] The end fixture 44 can be constructed with additional
features to facilitate the well treatment application. For example,
one or more valves 72 may be employed to control the flow of
chemicals from micro-tubing 34 to perforations 68. This valving
enables control over the additive dosage as additives 35 are
delivered to modify the well treatment fluid 39 routed externally
of micro-tubing 34 within tubing 36. The one or more valves 72 may
be controlled via signals, e.g. hydraulic or electric signals,
delivered through communication line 56. The end fixture 44 also
may comprise a jetting tool 74. Additional features may comprise a
magnet 76 positioned to minimize movement of the communication line
56. In some applications, the magnet 76 is exposed by dissolving or
otherwise removing the surrounding velocity boosters 64 after
positioning micro-tubing 34 and communication line 56 in the well.
The magnet 76 may be used to facilitate connection and/or
communication of signals between the communication line 56 and
downhole components, such as sensor system 58 and downhole tool
60.
[0031] As discussed above, communication line 56 may be constructed
in a variety of forms and may be coupled with other devices/systems
downhole via a variety of available wet connectors, inductive
couplings, and other types of connectors. The type of connector
employed (if a connector is needed) depends on the application and
use of communication line 56. In some applications, for example,
communication line 56 comprises an optical fiber 78 which may be
used to take measurements of the duration of the treatment,
flowback, and production. By way of example, optical fiber 78 may
comprise a distributed sensor system, such as a distributed
temperature sensor system. In some applications, the optical fiber
78 is designed to relay signals back and forth between the downhole
components and control system 62, including instruction signals
from the control system 62 to the downhole component(s). The
optical fiber 78 also may be used to deliver light, e.g. UV light,
for activation of additives delivered through micro-tubing 34
and/or to cause treatment fluid reaction. In some applications, the
optical fiber 78 may even be used in cooperation with the
micro-tubing 34 to measure fluid properties by illuminating a
sample of fluid using a colorimetric method.
[0032] Communication line 56 also may comprise additional signal
carriers, such as one or more electrical lines 80 designed to carry
data and/or power signals. For example, power signals may be
delivered through electric line 80 to power downhole tool 60 (see
FIG. 1). The electric line 80 also may be used to deliver voltage
for the purpose of generating heat to initiate reactions downhole.
In some applications, downhole tool 60 is an acoustic tool and
electric line 80 powers the tool 60 to provide acoustic or
ultrasound effects which help initiate downhole reaction of
chemicals.
[0033] The micro-tubing 34 is used to deliver a variety of
chemicals 35 downhole, e.g. additives used to modify properties of
the treatment system/treatment fluid 39 when mixed with the
treatment fluid at mixing region 42. By way of example,
micro-tubing 34 may be used to deliver additives comprising one or
more of crosslinkers, breakers, breaker aids, HT stabilizers,
corrosion inhibitors, rheology enhancers, enzymes, oxygen
scavengers, scale control additives, H2S scavengers, viscosity
boosters, activators, clay stabilizers, buffers, emulsifiers,
demulsifiers, pH adjusters, reaction activators, catalysts, and/or
other chemical additives. Additionally, the additive may be
delivered in a desired physical state, such as a liquid, a
solution, an emulsion, a colloid, a slurry, a foam, or a gas. The
type of additive chemical 35 delivered through micro-tubing 34 may
be selected according to the type of well treatment fluid 39
separately delivered downhole. Well treatment fluid 39 may comprise
fracturing fluid, but the fluid 39 also may comprise a variety of
other types of fluids, including slurries, acids, stimulants, and
other well treatment fluids. In an embodiment, the additive
chemical 35 comprises a gas that may be delivered through the
micro-tubing 34 to create a foam with fluids at the mixing region
42. In an embodiment, an additive chemical 35 may be delivered
downhole through the micro-tubing 34 to the mixing region 42 using
energized gas.
[0034] Furthermore, individual additives or multiple additives may
be delivered downhole to mixing region 42 via a single micro-tubing
34. In alternate embodiments, multiple additives may be delivered
downhole separately through multiple micro-tubings 34. The amount
of chemical additives added to the well treatment fluid in mixing
region 42 may be metered and controlled by, for example, one or
more of the valves 72. Additionally, the micro-tubing 34 may be
employed to inject tracers which are used for monitoring the well
application, such as the well treatment and/or well production. In
some applications, the micro-tubing 34 may even be employed for
fluid sampling by reversing the flow of fluid through the
micro-tubing.
[0035] Referring generally to FIG. 4, another embodiment of well
treatment system 22 is illustrated. In this embodiment,
micro-tubing 34 is routed down through larger tubing 36 at an
off-center position generally along the interior surface 40. The
micro-tubing 34 is joined with end fixture 44 via a tubing
connector 82. In this embodiment, end fixture 44 is generally
cylindrical and has an outer surface 84 which lies generally along
interior surface 40 of tubing 36. The end fixture 44 further
comprises an interior surface 86 which defines mixing region or
chamber 42.
[0036] A flow passage 88 is disposed between outer surface 84 and
interior surface 86 and delivers the additive 35 to a plurality of
injection ports 90. Injection ports 90 may be in the form of
openings/perforations formed through interior surface 86 to
introduce the chemical 35 into mixing region/chamber 42. The
injection ports 90 are oriented to impart a desired mixing flow. In
one embodiment, the injection ports 90 are distributed over the
full 360.degree. circumference along interior surface 86 around the
mixing region 42 (or along a circumference less than the
360.degree.) to provide a distributed injection of chemical 35 from
micro-tubing 34. The injection ports 90 also may be oriented to
induce turbulent flow to enhance mixing with the well treatment
fluid 39. In other applications, the injection ports 90 may be
oriented to induce a vortex similarly designed to enhance mixing
with the primary well treatment fluid 39. The mixing also may be
enhanced by employing a plurality of mixing vanes 92 along the
interior surface 86 of end fixture 44. The mixing vanes 92 may be
designed to act as an inline static mixer at the end of the
micro-tubing 34.
[0037] In the embodiment illustrated in FIG. 4, the end fixture 44
is pumped down through larger tubing 36 along with its micro-tubing
34. The pumping down may be facilitated by providing a temporary
restrictor 94, e.g. a burst disc, across the end fixture 44, as
illustrated. The end fixture 44 is pumped down until a lower end of
the fixture/micro-tubing is captured by securing mechanism 50. By
way of example, the securing mechanism 50 may comprise a combined
landing nipple and lock 96 located at a bottom end 98 of tubing 36
to lock the micro-tubing 34 in place. Additionally, the sensor
assembly 58 may be located in end fixture 44 and may comprise a
plurality of sensors 100 for detecting and/or monitoring a variety
of fluid and mixing related parameters, as discussed above.
[0038] Referring generally to FIG. 5, another embodiment of well
treatment system 22 is illustrated. In this embodiment, the end
fixture 44 is similar to the embodiment of end fixture 44 described
with reference to FIG. 4, and corresponding components have been
labeled with corresponding reference numerals. In the embodiment
illustrated in FIG. 5, however, the micro-tubing 34 is delivered
along an outside of tubing 36, e.g. coiled tubing. The micro-tubing
34 comprises a stinger end 102 which may be stung into a
corresponding receptacle 104 disposed on end fixture 44. A variety
of communication lines 56, e.g. fiber-optic cable 78 and/or
electrical line 80, may be deployed within micro-tubing 34.
Furthermore, the end fixture 44 may have a variety of
configurations designed to facilitate mixing of the additive
chemical 35 with the well treatment fluid 39 to effectively modify
the well treatment fluid at the downhole mixing region 42. Similar
to the previously described embodiment, the sensor package 58 may
comprise a variety of sensors coupled to one or more communication
lines 56 for detecting and monitoring a variety of treatment system
related parameters.
[0039] Another embodiment of well treatment system 22 is
illustrated in FIG. 6. In this embodiment, micro-tubing 34 is
combined with an end fixture 44 having a delivery and electronics
package (DEP) 106 which combines the electronics and sensor package
58 with a chemical delivery section 108 designed to deliver the
chemical additive 35 into mixing chamber 42. The DEP 106 is
deployed down through tubing 36 with micro-tubing 34 until the DEP
106 has landed in a corresponding securing mechanism 50, e.g.
landing and locking nipple 96. The DEP 106 may be landed inside a
tubing tailpipe 110 which has an internal diameter greater than the
diameter of the micro-tubing 34 and its end fixture 44. Once the
DEP 106 is landed, it may be latched in place.
[0040] During a well treatment operation, e.g. a well stimulation
operation, chemicals are delivered down through the micro-tubing 34
into the DEP 106 and out through openings 112, e.g. jets,
integrated into the DEP at the chemical delivery section 108. The
openings 112 may be positioned to evenly disperse the chemical 35
into the surrounding interior of tubing tailpipe 110. A variety of
mixing vanes 114 may be employed within the tubing tailpipe 110 to
help homogenize the chemicals 35 and well treatment fluids 39
before exiting the tailpipe assembly.
[0041] In some applications, communication line 56 may be added in
the form of a wireline attached to the DEP 106. The electronics and
sensor package 58 within the DEP 106 provides data back to the
surface through the communication line 56 as described above. For
example, sensor package 58 may be designed to detect and/or monitor
various well treatment operation parameters, including pH,
temperature, pressure, viscosity, depth, electrical conductivity,
fluid velocity, sound and/or vibration, and/or other parameters
related to the fluids and well treatment operation. Other types of
data, such as quality control data, also may be included in the
data stream delivered to control system 62 from electronics and
sensor package 58. As described with respect to other embodiments
herein, the communication line 56 may again comprise electric
lines, e.g. electric lines 80, to deliver data and/or power to
downhole mixing equipment incorporated into the DEP 106 or
positioned at other locations in the downhole equipment.
[0042] Once the well treatment operation is completed, a signal may
be sent downhole to initiate release of the DEP 106 from the
securing mechanism 50. The DEP 106 may then be retrieved to the
surface. In this example, the tubing tailpipe 110 remains in the
well without interfering with production operations. If subsequent
well treatments are desired, the DEP 106 can be redeployed down
through tubing 36 to securing mechanism 50 for delivery of desired
chemicals and/or gathering of data prior to and/or during the
subsequent well treatment operation. It should be noted that if a
stimulation treatment is delivered down the casing without tubing
36, a wireline retrievable packer assembly having a securing
mechanism/landing nipple for the DEP 106 may be placed and set
prior to deployment of the DEP. The DEP 106 may then be deployed
and locked in place at the securing mechanism 50.
[0043] Referring generally to FIG. 7, another embodiment of well
treatment system 22 is illustrated. In this embodiment, the end
fixture 44 is enlarged and contains a canister 116 with a
controllable valve 118. The canister 116 contains an additional
chemical 120 which may be delivered through valve 118 for mixing
with additive chemical 35 and with well treatment fluid 39. When
valve 118 is closed, there is no mixing of the chemical additive
35/well treatment fluid 39 and the additional chemical 120. The
additive chemical 35 can simply flow past the canister 116 for
mixing with well treatment fluid 39. When the valve 118 is opened,
the additional chemical 120 is released for mixing with the other
chemicals. In some embodiments, valve 118 is positioned to enable
flow of chemical 35 from micro-tubing 34 through canister 116, thus
allowing on demand release of the second chemical from canister
116. Depending on the type of chemical contained by canister 116,
the mixing can be accomplished internally or externally with
respect to the canister. Switching of valve 118 may be accomplished
by signals delivered through communication line 56 or by other
communication modes, such as pressure pulses, pumping down a ball
or dart, or by other suitable methods for communicating
instructions to the valve. In an embodiment, the micro-tubing 34
may be utilized to activate the contents of the canister 116
pumping a device or fluid to dissolve or otherwise open an opening
or openings in the canister 116 to release the contents 120 of the
canister 116.
[0044] Depending on the specific treatment application and
environment, the well treatment system 22 may be constructed
according to a variety of configurations. Various micro-tubing and
coiled tubing arrangements can be combined with a number of end
fixtures, sensor systems, and other components to facilitate the
delivery and mixing of chemicals at the downhole mixing region. In
some applications, for example, the micro-tubing 34 may be
constructed of non-conductive materials and conductive materials to
form non-conductive sections 122 and conductive sections 124 which
may be employed to measure electrical properties of the surrounding
formation, as illustrated in FIG. 7. In other applications, the
micro-tubing 34 may be designed to operate in conjunction with
optical fibers of communication line 56 to measure gas hold up. By
way of additional examples, the micro-tubing 34 may be used in
selectively treating one or more well treatment regions 32 disposed
along wellbore 24. The micro-tubing also may be used to assist the
detection and monitoring of a variety of parameters, e.g. the
micro-tubing may be employed as a pipe rheometer to measure fluid
viscosity downhole. In an embodiment, the micro-tubing 34 may be
constructed of a material that may subsequently degrade with time
after having delivered a specific chemical downhole. In an
embodiment, the micro-tubing 34 may be constructed of a high
strength composite material.
[0045] Additionally, control over the chemical mixing may be
automated via control system 62. In this example, signals are
provided to control system 62 from the various sensors 100 located
downhole, and the control system 62 automatically responds by
controlling delivery of the desired chemical additives to optimize
fluid chemistries of mixed fluids delivered into the surrounding
formation. The shape, configuration, and materials used to
construct the various components of the overall well treatment
system 22 may be adjusted as desired for a given well treatment
operation and the characteristics of the surrounding
environment.
[0046] In an embodiment, the micro-tubing 34 is utilized to pump
air or fluid in the same direction within the micro-tubing. In an
embodiment, the micro-tubing 34 is loaded utilizing vacuum or
negative pressure from one end of the micro-tubing 34. In an
embodiment, the micro-tubing 34 defines one or more compartments of
similar outside diameter or different radii, whereby the amount of
material delivered by the micro-tubing 34, such as the
chemical/additive 35, may be controlled by selected the
compartments of different radii. In an embodiment, the
chemical/additive 35 may be pumped through the micro-tubing 34 at
the time of treatment in order to modify treatment fluid 39, such
as at the mixing region 42. In an embodiment, the chemical/additive
35 may be pumped after the treatment during flowback, such as a
corrosion inhibitor to reduce the corrosion tendency due to the hot
unspent acid coming back after an acid treatment. In an embodiment,
the chemical/additive 35 and/or the treatment fluid 39 may comprise
two treatment fluids or chemical additives that individually will
not affect the fluid properties and a third, intermediate fluid or
additive that will react with the two fluids and change the fluid
properties, such as, but not limited to, by a fluid pumped through
annulus outside the tubing 36, another fluid pumped down inside the
tubing 36 and a fluid which is mixed after injection from the
micro-tubing 34.
[0047] In an embodiment, the micro-tubing 34 it utilized to perform
depth measurements, such as by using the fiber optic,
temperature/vibration correlation against known perforation depth
or by recording deployed length of the micro-tubing 34 from
surface. In an embodiment, pressure measurements may be performed
by the micro-tubing 34, especially while not pumping through the
micro-tubing 34. The micro-tubing 34 may be used as a very
effective "dead string". The micro-tubing 34 which will carry
reasonably clean & homogeneous fluids 35 may be used as a very
effective pressure guide to transmit transient pressure information
either upwards or downwards, which may be utilized for telemetry
purposes, or reservoir interpretation, such as well testing,
fracture closure pressure determination, etc. In an embodiment, the
larger tubing 36 comprises coiled tubing having long perforated
intervals in an end of the tubing 36. The micro-tubing 34 and plug
46 may then be dynamically positioned up or down the perforated
interval to change the ratio (and the location) of treated fluid
vs. untreated fluid. The well treatment system 22 may be utilized
to treat multiple zones at the same time with different fluid
rheologies, such as by pumping fluid through annulus outside the
tubing 36, pumping fluid down inside the tubing 36, and by pumping
another fluid 35 through the micro-tubing 34. In an embodiment,
fluids (treatment fluids or reservoir fluids) may be backflowed
into the micro-tubing 34 in order to take fluid samples during or
after treatment. In an embodiment, positioning, actuating, and
measuring of the plug 46 may be handled via slickline or wireline
deployed in a coiled tubing 36.
[0048] Accordingly, although a few embodiments of the present
disclosure have been described in detail above, those of ordinary
skill in the art will readily appreciate that many modifications
are possible without materially departing from the teachings of
this invention. Such modifications are intended to be included
within the scope of this invention as defined in the claims.
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