U.S. patent application number 14/145888 was filed with the patent office on 2014-07-10 for encapsulating an electric submersible pump cable in coiled tubing.
This patent application is currently assigned to SCHLUMBERGER TECHNOLOGY CORPORATION. The applicant listed for this patent is SCHLUMBERGER TECHNOLOGY CORPORATION. Invention is credited to Sheng Chang, Matthew Garber, Kevin T. Scarsdale, Burcu Unal, Joseph Varkey.
Application Number | 20140190706 14/145888 |
Document ID | / |
Family ID | 51060119 |
Filed Date | 2014-07-10 |
United States Patent
Application |
20140190706 |
Kind Code |
A1 |
Varkey; Joseph ; et
al. |
July 10, 2014 |
ENCAPSULATING AN ELECTRIC SUBMERSIBLE PUMP CABLE IN COILED
TUBING
Abstract
An electric submersible pump (ESP) cable encapsulated in coiled
tubing is provided. In an example process, ESP cable is drawn
through coiled tubing. Liquid filler that cures into a supportive
solid matrix is pumped into the coiled tubing. The solid matrix may
be a rubberized filler or a closed-cell foam. Additives in the
liquid filler can compensate for thermal expansion during operation
of the ESP, or decrease overall weight of the solid matrix, or
swell in the presence of oil, water, salt, or gas to seal a hole in
the coiled tubing. The coiled tubing may be formed and seam-welded
around the ESP cable from flat steel strip. A long coiled tubing
resistant to stretch for deep wells may be produced by providing
extra ESP cable for slack before the liquid filler cures into solid
matrix. The coiled tubing may be clad with corrosion-resistant
alloy for corrosive wells.
Inventors: |
Varkey; Joseph; (Sugar Land,
TX) ; Unal; Burcu; (Richmond, TX) ; Chang;
Sheng; (Sugar Land, TX) ; Garber; Matthew;
(Sugar Land, TX) ; Scarsdale; Kevin T.; (Pearland,
TX) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SCHLUMBERGER TECHNOLOGY CORPORATION |
Houston |
TX |
US |
|
|
Assignee: |
SCHLUMBERGER TECHNOLOGY
CORPORATION
Houston
TX
|
Family ID: |
51060119 |
Appl. No.: |
14/145888 |
Filed: |
December 31, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61748383 |
Jan 2, 2013 |
|
|
|
Current U.S.
Class: |
166/378 ;
166/66.4 |
Current CPC
Class: |
E21B 17/206 20130101;
H01B 7/046 20130101; E21B 43/128 20130101; F04B 47/06 20130101;
E21B 19/22 20130101 |
Class at
Publication: |
166/378 ;
166/66.4 |
International
Class: |
F04B 47/06 20060101
F04B047/06; E21B 4/04 20060101 E21B004/04 |
Claims
1. An apparatus, comprising: a coiled tubing for deploying an
electrical apparatus in a well; a cable in the coiled tubing in
communication with the electrical apparatus; and a liquid filler
occupying a space between an outside of the cable and an inside of
the coiled tubing, the liquid filler curing into a supportive solid
matrix.
2. The apparatus of claim 1, wherein the cable powers the
electrical apparatus and the electrical apparatus comprises an
electric submersible pump (ESP).
3. The apparatus of claim 1, wherein the supportive solid matrix
comprises a rubberized filler.
4. The apparatus of claim 1, wherein the supportive solid matrix
comprises a closed-cell foam matrix.
5. The apparatus of claim 1, wherein the supportive solid matrix
comprises one of an epoxy, a silicone, an ether, an ester, a liquid
fluorosilicone, a liquid fluoroelastomer, a SHIN-ETSU-SIFEL potting
gel, a urethane, or a polymer that solidifies over time or when
exposed to heat.
6. The apparatus of claim 1, wherein the supportive solid matrix
further comprises an additive compensating for thermal expansion of
the cable during an operation of the electrical apparatus.
7. The apparatus of claim 1, wherein the supportive solid matrix
further comprises an additive for decreasing a weight of the
supportive solid matrix, including one of a chopped carbon fiber, a
glass fiber, a synthetic fiber, glass beads with air, formed
particles, or chopped formed particles.
8. The apparatus of claim 1, wherein the supportive solid matrix
further comprises an additive to swell in the presence of one of an
oil, water, a salt, or a gas to seal off a hole in the coiled
tubing.
9. The apparatus of claim 1, wherein the liquid filler cures into
the supportive solid matrix due to an elapse of time or when
exposed to heat.
10. The apparatus of claim 1, wherein the supportive solid matrix
remains pliable and deformable in response to a stretch or a
movement of the cable in relation to the coiled tubing, or in
response to a deformation of the coiled tubing deviating around a
spool, a reel, a drum, a well head, a goose neck, an injector, a
joint, a casing, an annulus, a well wall, a well curve, a hangar, a
termination, or a sheave.
11. The apparatus of claim 1, wherein the cable comprises one of a
round cable, a flat cable, a coaxial cable, or a helically coiled
cable.
12. The apparatus of claim 1, wherein the coiled tubing comprises a
seam-welded tube formed over the cable and an excess of the cable
comprising a slack.
13. The apparatus of claim 1, wherein the coiled tubing further
comprises a corrosion resistant cladding.
14. The apparatus of claim 13, further comprising a low-carbon
steel coiled tubing and a metallic bonding layer added on the
low-carbon steel coiled tubing, wherein the corrosion resistant
cladding bonds to the low-carbon steel coiled tubing via a chemical
affinity with the metallic bonding layer and an associated heat of
reaction from the chemical affinity.
15. A method, comprising: pulling a cable into a coiled tubing for
deploying an electrical apparatus in a well; and pumping a liquid
filler that cures into a solid matrix into the coiled tubing to
secure the cable in relation to the coiled tubing.
16. The method of claim 15, wherein the solid matrix comprises one
of a rubberized filler or a closed-cell-foam.
17. The method of claim 15, further comprising drawing the coiled
tubing down onto the solid filler when air gaps cause separation
between the solid filler and the coiled tubing.
18. A method, comprising: shaping a continuous piece of flat metal
around a cable for communicating power or data to an electrical
apparatus in a well; seam-welding the continuous piece of metal
into a coiled tubing around the cable; and pumping a liquid filler
that cures into a solid filler into the coiled tubing to secure the
cable in relation to the coiled tubing.
19. The method of claim 18, further comprising shaping the
continuous piece of flat metal around an excess of the cable to
provide a slack for the cable when the coiled tubing stretches
under an increased weight in a deep well application.
20. The method of claim 18, further comprising cladding an outside
surface of the coiled tubing with a corrosion-resistant metal or
alloy to resist a chemical corrosion.
Description
RELATED APPLICATIONS
[0001] This patent application claims the benefit of priority to
U.S. Provisional Patent Application No. 61/748,383 filed on Jan. 2,
2013 and incorporated herein by reference in its entirety.
BACKGROUND
[0002] In the oil and gas industries, coiled tubing ("coil") is
metal piping, usually between 1.00-3.25 inches in diameter, used
for well intervention and sometimes used for production tubing.
Coiled tubing can be pushed into a well rather than depending only
on gravity. The coiled tubing is a continuous length of tubular
steel or composite that is flexible enough to be wound on a large
reel for transportation. A coiled tubing unit is composed of a reel
with the coiled tubing, an injector, control console, power supply,
and well-control stack. The coiled tubing is injected into an
existing production string, unwound from the reel and inserted into
the well. The coiled tubing may be referred to as "coiled" even
when it has been unreeled into a well. When a well lacks enough
pressure, then an electric submersible pump (ESP) may be suspended
from the coiled tubing to apply artificial lift to recover
hydrocarbon resources.
[0003] In conventional ESP deployment from coiled tubing, ESP
electrical cable may be pulled into the coiled tubing using a wire
or wire rope that is pumped into the coil using "pig" attached to
the wire rope. The downhole ends of the coiled tubing and ESP cable
are terminated and the ESP is hung from the termination of the
coiled tubing. The coiled tubing is terminated at the top of well
with an ability to allow slack management of cable inside the
coiled tubing, to mitigate forces on the upper connection due to
the cable sliding further down into the coiled tubing over time. To
keep the cable supported inside, the coiled tubing is
conventionally filled with fluid, such as glycol.
SUMMARY
[0004] An electric submersible pump (ESP) cable encapsulated in
coiled tubing is provided. An apparatus comprises a coiled tubing
for deploying an electrical apparatus in a well, a cable in the
coiled tubing in communication with the electrical apparatus, and a
liquid filler occupying a space between an outside of the cable and
an inside of the coiled tubing, the liquid filler curing into a
supportive solid matrix. An example method comprises pulling a
cable into a coiled tubing for deploying an electrical apparatus in
a well, and pumping a liquid filler that cures into a solid matrix
into the coiled tubing to secure the cable in relation to the
coiled tubing. Another example method comprises shaping a
continuous piece of flat metal around a cable for communicating
power or data to an electrical apparatus in a well, seam-welding
the continuous piece of metal into a coiled tubing around the
cable, and pumping a liquid filler that cures into a solid filler
into the coiled tubing to secure the cable in relation to the
coiled tubing.
[0005] This summary section is not intended to give a full
description of the subject matter. A detailed description with
example embodiments follows.
BRIEF DESCRIPTION OF THE DRAWINGS
[0006] FIG. 1 is a diagram of an example coiled-tubing-deployed ESP
cable with a liquid filler that cures into a supportive rubberized
matrix.
[0007] FIG. 2 is a diagram of an example coiled-tubing-deployed ESP
cable with a liquid filler that cures into a supportive closed-cell
foam matrix.
[0008] FIG. 3 is a diagram of different example cable types and
configurations suitable for encapsulation within a coiled
tubing.
[0009] FIG. 4 is a diagram of example construction of a seam-welded
tube around an ESP cable with slack and a liquid filler that cures
into a supportive rubberized matrix for deep well deployment.
[0010] FIG. 5 is a diagram of example corrosion-resistant cladding
around coiled tubing encapsulating an ESP cable.
[0011] FIG. 6 is a flow diagram of an example method of creating a
coiled-tubing deployed ESP cable with solid filler matrix.
[0012] FIG. 7 is a flow diagram of an example method of creating a
coiled-tubing deployed ESP cable for deep wells.
[0013] FIG. 8 is a flow diagram of an example method of creating a
coiled-tubing deployed ESP cable with solid filler matrix suitable
for corrosive wells.
DETAILED DESCRIPTION
Overview
[0014] This disclosure describes encapsulating electric submersible
pump (ESP) cables that are within coiled tubing. An ESP cable may
be either a power cable or a control cable, or both, for providing
power and control to an ESP. In a particular scheme, coiled tubing
physically suspends the ESP within a well, with ESP cable residing
inside the coiled tubing. In an implementation described herein,
the coiled tubing, with the ESP cable inside, is filled with a
liquid, which then cures to encapsulate the ESP cable within a
solid matrix inside the coiled tubing. The solid matrix addresses
problems that occur with conventional fluid fillers, and provides a
host of advantages.
[0015] In an example process, referring to FIG. 1, an ESP cable 100
is placed into or pulled inside of coiled tubing 102 filled with
air 104, which is then pumped with a liquid filler 106 in fluid
state that cures into a solid matrix 108 over time or when exposed
to heat. The resulting solid matrix 108 may consist of a rubberized
solid 108. In FIG. 2, the resulting solid filler 208 may consist of
a closed-cell foam 208 that permanently secures the ESP cable 100
inside the coiled tubing 102. As shown in FIG. 3, the example
coiled-tubing deployed ESP cable described herein can use a round
ESP cable 100 (e.g., tri-conductor), a flat ESP cable 302, a
helically disposed ESP cable 304, a round ESP cable having only a
single conductor 306, a coaxial ESP cable, or other cross-sectional
shapes and types of the ESP cable 100.
[0016] In another implementation shown in FIG. 4, a continuous
strip of steel 402 or other metal that is to become the coiled
tubing 402 is formed and seam-welded 404 around the ESP cable 400.
A liquid filler 406 is pumped in, which cures into a solid matrix
408. This example process can be used to create a coiled tubing
with encapsulated ESP cable suitable for deep wells, over 8000 feet
deep. For deep wells, the continuous piece of steel 402 or other
metal is seam-welded 404 around a loosely lying or helically
disposed ESP cable, such as ESP cable 304 (FIG. 3) that has slack
in its pre-encapsulated configuration. The seam-welded steel 402
becomes the coiled tubing 402. The coiled tubing 402 can then be
pressure tested, and then pumped with the liquid filler 406 that
cures into the solid matrix 408. The built-in slack imparts some
flexibility when the coiled tubing 402 must deviate around
obstacles during well insertion or intervention, or when the ESP
cable 400 later tends to descend within the coiled tubing 402 by
gravity under the increased weight of its long length in a deep
well deployment.
[0017] In an example implementation shown in FIG. 5, the ESP cable
100 (or 302 or 306, for example) encapsulated within the coiled
tubing 102 is made corrosion resistant by adding an exterior
cladding 500 of chemical-resistant alloy.
Example Solid Fillers
[0018] Conventional coiled tubing containing an ESP cable and
filled interiorly with glycol presents some problems. At high
downhole temperatures, glycol can react with and damage the ESP
cable. In practical use, filling the conventional coiled tubing
with conventional fluid on a rig is a difficult process. Fluid
access through the well's "tree" (assembly of valves, spools, and
fittings) is required to compensate pressures within the
conventional coiled tubing. Also, fluid in the coiled tubing may
not be compatible with subsea tree system. Open communication of
fluid to the conventional coiled tubing must be maintained during
conventional deployment. Cable loss management conventionally
requires a large canister to coil the cable, interfering with the
tree wellbore and flow characteristics. There are also conventional
production limitations on length of a coiled tubing containing an
ESP cable, of approximately three kilometers. Large diameter coiled
tubing is conventionally required to allow the ESP cable to be
pulled into the interior of the coiled tubing. The large diameter
of the coiled tubing translates into higher tubing weights. Bulky
terminations are therefore conventionally required to support the
excessive weight of large tubing. Slack management requirements on
both power and control lines conventionally require complex coiling
and splicing, at least for deeper wells.
[0019] Coiled tubing methods can be more widely implemented in
general with the example implementations described below, which
provide compact, solid, fully supported cable-in-tubing
construction. The example implementations provide one or more
benefits, such as 1) fully supported construction, 2) no cable loss
management required, 3) compact end terminations, 4) continuous
coiled tubing lengths beyond three kilometers, 5) integrated
service lines and control lines fully supported, 6) thermal
expansion of the cable can be managed using slack in the cable and
additives that can be added into the fluid before solidifying, 7)
total weight can be reduced by adding additives that lower the
weight of the cured solid, 8) if pin holes develop on the coiled
tubing in the solid-matrix-filled tube design, then fluid migration
is limited, depending on the pressure differential, and 9)
additives can be included in the pre-cured solid filler that swell
in the presence of oil, water, salt, or gas to seal off leakage
into the coiled tubing from an oil well, providing a self-healing
coiled tubing deployment.
Example Filler Materials
[0020] Example implementations may use a polymeric fluid as the
liquid filler 106 that cures into a solid matrix to provide a
compact coiled tubing 102 with ESP cable 100 fully supported by
solid filler 108 in the coiled tubing 102. Suitable pumpable filler
materials cure in place into a deformable solid 108 that allows for
some stretch and movement of the ESP cable 100 when the coiled
tubing 102 passes around such items as goose necks, injectors,
deviations with in the well, sheaves, spools, reels, drums, joints,
casings, or as the coiled tubing 102 stretches due to its own
weight or thermal expansion in offshore, deep well, or long well
deployments.
[0021] Example materials for the solid filler 108 include epoxies,
silicones, ethers, esters, liquid fluorosilicones, liquid
fluoroelastomers, such as a SHIN-ETSU-SIFEL potting gel
(combination of a perfluoropolyether backbone with a terminal
silicone crosslinking group), urethanes, or other polymers that
solidify over time or when exposed to heat (Shin-Etsu Chemical
Company, Ltd, Tokyo, Japan).
[0022] Additives may be included that cause the example filler
material 108 to swell if exposed to specific materials, such as
oil, gas, water, or salt encountered in a downhole environment. The
swellable additive can thus respond to pinhole leaks to make a
self-plugging coiled tubing 102. Likewise, the example solid filler
material 108 in its initial liquid form 106 may incorporate
additives before being pumped into the coiled tubing 102 to lower
density, increase buoyancy, or minimize thermal expansion. The
lower density filler 108 can thereby reduce the overall weight of
the coiled tubing-encapsulated cable. Such additives may include
chopped carbon fiber, glass fiber, synthetic fiber, glass beads
with air, formed particles, chopped formed particles, and so
forth.
[0023] Referring to FIG. 2, the example solid matrix 208 may
consist of a closed-cell foam 208 or 208', initially in liquid
fluid state 106, exhibiting desirable properties of curability,
flexibility, and chemical resistance. In an implementation, the
solid foam 208 may result from gas bubbles remaining in the solid
filler 208 when curing from liquid to solid. In another
implementation, solid parts of the solid closed-cell foam 208' may
consist mainly of the solid walls forming the closed cells of the
foam 208'. In an implementation, a foam 208 may be selected to have
an affinity with the metal of the coiled tubing 102 in order to
create a chemical bond between the two, when needed.
Example Coiled Tubing
[0024] Example coiled tubing 102 for use in the example
implementations may be a suitable high-strength, low-carbon steel
as is often used in conventional coiled tubing. For "sour well"
applications where exposure to hydrogen sulfide (H.sub.2S) or
carbon dioxide (CO.sub.2) is anticipated, a layer of chemically
resistant cladding, such as INCONEL alloy, may be added or drawn
over the coiled tubing (see FIG. 6) for enhanced chemical
resistance, or the entire coiled tubing 102 may be made out of
INCONEL265 or other suitable alloys (Special Metals Corporation,
New Hartford, N.Y.).
Coiled-tubing-deployed ESP Cable with Rubberized Filler
[0025] FIG. 1 shows an example ESP cable 100 encapsulated in a
rubberized solid 108 inside a coiled tubing 102. In an
implementation, the example coiled-tubing-deployed ESP cable 100 is
produced by pulling the ESP cable 100 into the air-filled space
inside the coiled tubing 102, or attaching the ESP cable 100 to a
slug or a pig that may be pumped into the coiled tubing 102 by
compressed gas or other fluid. Once the ESP cable 100 is inside the
coiled tubing 102, a curable liquid 106 is pumped in to replace the
air, gas, or fluid in the coiled tubing 102. The curable liquid 106
sets to form a solid rubberized matrix 108 that holds the ESP cable
100 in place and prevents the ESP cable 100 from yielding when the
coiled tubing 102 is bent over sheaves and drums or passed over
goose necks, deviations within a well, or stretched due to its own
weight in offshore or deep well deployments. Thus, the ESP cable
100 may have some excess length and slack intentionally built into
its placement in the coiled tubing 102 when the ESP cable 100 is
inserted into the coiled tubing 102.
Coiled-tubing-deployed ESP Cable with Closed-cell Foam
[0026] FIG. 2 shows an example ESP cable 100 encapsulated in a
solid foam 208 inside a coiled tubing 102. In an implementation,
the example coiled-tubing-deployed ESP cable 100 is produced by
pulling the ESP cable 100 into the air-filled space inside the
coiled tubing 102, or attaching the ESP cable 100 to a pig that may
be pumped into the coiled tubing 102 by compressed gas or other
fluid. Once the ESP cable 100 is inside the coiled tubing 102, a
curable liquid 106 is pumped in to replace the air, gas, or fluid
in the coiled tubing 102. In this case, the curable liquid 106 may
consist of a polymeric fluid that sets to form the closed-cell foam
208 that holds the ESP cable 100 in place and helps to prevent the
ESP cable 100 from yielding when the coiled tubing 102 is bent over
sheaves, drums, over goose necks, and well curves, or stretched due
to its own weight in offshore or deep well deployments. The ESP
cable 100 may have some slack intentionally built into its
placement in the coiled tubing 102 when the ESP cable 100 is
inserted into the coiled tubing 102, before the curable liquid 106
sets into the solid closed-cell foam.
[0027] The closed-cell foam filler 208 can impart more buoyancy
than many solid rubberized fillers 108 and reduce the overall
weight of the coiled tubing 102 with ESP cable 100 and foam filler
208 inside.
Example ESP cable
[0028] FIG. 3 shows example ESP cables. The ESP cable to be used in
a coiled tubing deployment may be a round ESP cable 100, such as a
tri-conductor cable for three-phase power, a flat ESP cable 302, a
helically coiled ESP cable 304, a single conductor power or control
cable 306, a coaxial style ESP cable, or a cable of other
geometrical cross-section or type. The ESP cable 100 (or 302 or 304
or 306) may be centralized or stood-off from the inner walls of the
coiled tubing 102 with periodic supports, such as periodic fins 308
or studs, that allow the pumped liquid filler 106 to pass by the
supports to fill the voids in the coiled-tubing 102 until the
filler 106 cures.
Coiled-tubing-deployed ESP Cable for Deeper Wells
[0029] Pulling an ESP cable 100 using a pumped-in wire or wire rope
into coiled tubing 102 becomes increasingly difficult as the length
of the coiled tubing 102 increases. One solution has been to form a
large-diameter outer jacket of solid material over the ESP cable
100 and then seam-weld a tube over the jacket to ultimately create
a completely filled coiled tube. An example manufacturing process
for this conventional solution includes applying a thick outer
jacket to a standard ESP cable, applying a continuous piece of
steel to the jacketed ESP cable, forming the steel into a loose
circular tube over the jacketed ESP cable through a series of
shaping rollers, seam welding the loose circular tube to form the a
completed steel tube, and drawing down the steel tube over the
jacketed ESP cable to complete the coiled-tubing-deployed ESP
cable.
[0030] One drawback of this conventional method is that there is no
opportunity to pressure test the resulting coiled tubing to ensure
that the seam weld is continuous and defect free. In this
conventional process, there is also no possibility to impart slack
in the ESP cable and so there is a possibility of yielding the
cable as the coiled tubing stretches beyond the yield point of the
ESP conductors inside. During the welding process a waste
consisting of 10% to 15% scrap is also common, and a percentage of
cable is also lost during this conventional process.
[0031] FIG. 4 shows parts of an example manufacturing process,
addressing deeper wells that need coiled tubing lengths greater
than approximately 8000 feet (greater than 2.4 kilometers). A strip
of continuous steel 402 is formed lengthwise into a rounded trough
around an ESP cable 400, using forms and shaping rollers.
Additional series of rollers form the metal 402 into a loose
circular tube 402 over the ESP cable 402. The ESP cable 402 can be
centralized or stood-off, as described above, with fins 308,
supports, or studs, etc. When the loose circular tube 402 is
seam-welded 404 to make coiled tubing, the ESP cable 400 is placed
in a configuration that is loose with slack, to provide play for
the ESP cable 400 in the finished coiled tubing 402. The resulting
coiled tubing 402 can then be pressure tested, which is not
possible in the conventional manufacture technique described above.
The resulting coiled tubing 402 can then be filled with a curable
liquid 406 that becomes the solid filler 408. If the welding of the
seam-welded coiled tubing 402 is faulty, then the ESP cable 400 can
be retrieved from the coiled tubing 402 without scrapping both the
ESP cable 400 and the coiled tubing 402.
Resistant Cladding
[0032] FIG. 5 shows example coiled tubing 102 with chemically
resistant cladding 500. In "sour well" applications where exposure
to hydrogen sulfide (H.sub.2S) or carbon dioxide (CO.sub.2) is
anticipated, standard low-carbon steel quickly deteriorates and
fails. Special alloy materials for the coiled tubing 102, such as
INCONEL alloy, can be used as a substitute for the low-carbon
steel, but this type of alloy tubing can be cost-prohibitive. An
example implementation applies a suitable thickness of a layer of a
resistant alloy 500, such as an INCONEL cladding, over example
coiled tubing 102 or seam-welded coiled tubing 402 that includes a
solid-filler stabilized cable, such as ESP cable 100 or ESP cable
302, for example.
[0033] A metallic coating, such as a metallic bonding layer 502,
may be applied first over the outer surface of the low-carbon steel
coiled tubing 102 or 402 so that when the resistant cladding 500,
such as INCONEL alloy is drawn down to the low carbon steel 102 or
402 the heat generated and the chemical affinity with the metallic
bonding layer 502 allows the bonding of the resistant cladding 500
to the steel coiled tubing 102 or 402. The ESP cable 100 (or 302 or
304 or 306) inside the coiled tubing 102 or 402 may be round, flat,
helical, coaxial, or of other suitable configuration.
Example Methods
[0034] FIG. 6 shows an example method 600 of creating a
coiled-tubing deployed ESP cable with supportive solid matrix. In
the flow diagram, the operations are summarized in individual
blocks.
[0035] At block 602, a coiled tube of appropriate size for
inserting into a well is selected.
[0036] At block 604, a wire or wire rope is pumped into the coiled
tube by a fluid, such as air or water. For example, the air or
water may move a "pig" attached to a first end of the wire rope to
draw the wire rope through the coiled tube. An ESP cable is
attached to the other end of the wire rope, and can be pulled
through the coiled tubing by the wire rope. The fluid used to pump
the ESP cable may be replaced by air.
[0037] At block 606, a liquid filler that cures into a solid matrix
is pumped into the coiled tubing. The liquid filler may cure over
time or through application of heat into a rubberized matrix or a
closed-cell foam. Both ends of the coiled tubing may be capped and
a slight pressure applied during the cure time to minimize
shrinkage. The tubing may be drawn down onto the cured matrix when
shrinkage or air gaps cause separation between the ESP cable
elements and the inner wall of the coiled tubing.
[0038] The ESP cable used for the above example process may be
round, flat or another suitable configuration. The ESP conductors
may be bundled into a helix to match the thermal expansion of the
coiled tubing. Additionally, centralizers or stand-offs, designed
to allow through-flow, can be used along the length of the ESP
cable to keep the cable off the tubing inner wall, during curing
time.
[0039] FIG. 7 shows an example method 700 of creating a
coiled-tubing deployed ESP cable for deep wells. In the flow
diagram, the operations are summarized in individual blocks.
[0040] At block 702, a continuous piece of flat steel or other
metal is formed through a series of shaping rollers into a length
with an arc-shaped or trough-shaped cross-section.
[0041] At block 704, an ESP cable with extra slack is applied into
the bottom of the arc-shaped or trough-shaped metal. The ESP cable
and its conductors may have a round, flat, or other cross-sectional
profile, or may be of helical or coaxial configuration. An
additional series of rollers form the metal into a loose circular
tube over the ESP cable. The cable can be centralized or stood-off,
as described above.
[0042] At block 706, the adjacent edges of the metal are
seam-welded to form a completed coiled tube. The completed tube may
be pressure-tested. When a faulty seam weld is detected during the
pressure testing, then the ESP cable can be retrieved from the
coiled tubing without scrapping both the ESP cable and the coiled
tubing.
[0043] At block 708, a liquid filler that cures into a solid matrix
or forms into a closed-cell foam is pumped in to fill the space
between the ESP cable and the coiled tubing.
[0044] The ESP cable is given slack in the coiled tubing so that
the ESP cable does not lay completely straight in the coiled tubing
before the curable or formable fluid is pumped in. The slack or
excess length helps to minimize the possibility of the conductors
of the ESP cable yielding when the coiled tubing stretches under
its own increased weight due to extended length.
[0045] FIG. 8 shows an example method 800 of creating a
coiled-tubing deployed ESP cable with solid filler matrix and
suitable for corrosive wells. In the flow diagram, the operations
are summarized in individual blocks.
[0046] At block 802, a coiled tube of appropriate size for
inserting into a well is selected.
[0047] At block 804, an ESP cable is drawn through the coiled
tubing.
[0048] At block 806, a liquid filler that cures into a solid matrix
is pumped into the coiled tubing.
[0049] At block 808, a layer of corrosion-resistant metal or alloy
is applied around the outside of the coiled tubing. For example,
INCONEL alloy may be applied as a cladding around the coiled
tubing.
Conclusion
[0050] Although only a few example embodiments have been described
in detail above, those skilled in the art will readily appreciate
that many modifications are possible in the example embodiments
without materially departing from the subject matter. Accordingly,
all such modifications are intended to be included within the scope
of this disclosure as defined in the following claims. In the
claims, means-plus-function clauses are intended to cover the
structures described herein as performing the recited function and
not only structural equivalents, but also equivalent structures. It
is the express intention of the applicant not to invoke 35 U.S.C.
.sctn.112, paragraph 6 for any limitations of any of the claims
herein, except for those in which the claim expressly uses the
words `means for` together with an associated function.
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