U.S. patent application number 13/853231 was filed with the patent office on 2013-08-22 for aqueous-based insulating fluids and related methods.
This patent application is currently assigned to Halliburton Energy Services, Inc.. The applicant listed for this patent is Halliburton Energy Services, Inc.. Invention is credited to Ryan Ezell.
Application Number | 20130213656 13/853231 |
Document ID | / |
Family ID | 48981400 |
Filed Date | 2013-08-22 |
United States Patent
Application |
20130213656 |
Kind Code |
A1 |
Ezell; Ryan |
August 22, 2013 |
Aqueous-Based Insulating Fluids and Related Methods
Abstract
Aqueous-based insulating fluids that have greater stability at
high temperatures with lower thermal conductivity may be used, for
example, in applications requiring an insulating fluid such as
pipeline and subterranean applications. For example, a method may
include providing an aqueous-based insulating fluid in an annulus
between a riser column and an outer casing disposed thereabout, the
riser column connecting a wellbore penetrating a subterranean
formation to a floating surface rig; and flowing a fluid through
the riser column and the wellbore.
Inventors: |
Ezell; Ryan; (Houston,
TX) |
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Applicant: |
Name |
City |
State |
Country |
Type |
Halliburton Energy Services, Inc.; |
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US |
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Assignee: |
Halliburton Energy Services,
Inc.
Houston
TX
|
Family ID: |
48981400 |
Appl. No.: |
13/853231 |
Filed: |
March 29, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12046086 |
Mar 11, 2008 |
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13853231 |
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11685909 |
Mar 14, 2007 |
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12046086 |
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Current U.S.
Class: |
166/302 ;
166/308.5; 175/67 |
Current CPC
Class: |
C10M 2207/0406 20130101;
C10M 2209/1055 20130101; E21B 36/003 20130101; E21B 43/26 20130101;
C10M 173/02 20130101; C10M 2207/0225 20130101; F16L 59/143
20130101; C10M 2209/1085 20130101; C10M 2209/1045 20130101; E21B
7/18 20130101; F16L 59/14 20130101 |
Class at
Publication: |
166/302 ; 175/67;
166/308.5 |
International
Class: |
E21B 36/00 20060101
E21B036/00; E21B 43/26 20060101 E21B043/26; E21B 7/18 20060101
E21B007/18 |
Claims
1. A method comprising: providing an aqueous-based insulating fluid
in an annulus between a riser column and an outer casing disposed
thereabout, the riser column connecting a wellbore penetrating a
subterranean formation to a floating surface rig; and flowing a
fluid through the riser column and the wellbore.
2. The method of claim 1, wherein providing comprises placing the
aqueous-based insulating fluid in the annulus, the aqueous-based
insulating fluid comprising an aqueous base fluid, a water-miscible
organic liquid, a synthetic polymer, and a crosslinker; and
crosslinking the synthetic polymer with the crosslinker.
3. The method of claim 2, wherein crosslinking comprises exposing
the aqueous-based insulating fluid to a temperature of about
90.degree. F. or greater.
4. The method of claim 3, wherein exposing occurs before placing
the aqueous-based insulating fluid in the annulus.
5. The method of claim 3, wherein exposing occurs after placing the
aqueous-based insulating fluid in the annulus.
6. The method of claim 1, wherein the aqueous-based insulating
fluid comprises an aqueous base fluid, a water-miscible organic
liquid, and a layered silicate.
7. The method of claim 1, wherein the fluid is a drilling
fluid.
8. The method of claim 1 further comprising: performing a managed
pressure drilling operation to extend the wellbore in the
subterranean formation.
9. The method of claim 1 further comprising: performing a dual
gradient drilling operation to extend the wellbore in the
subterranean formation.
10. The method of claim 1, wherein the fluid is a formation
fluid.
11. The method of claim 1, wherein at least a portion of the
aqueous-based insulating fluid is exposed to a temperature of about
250.degree. F. to about 400.degree. F. for 30 days or greater.
12. The method of claim 1, wherein the fluid is about 20% warmer or
greater than if flowing through a similar riser without the
aqueous-based insulating fluid.
13. A method comprising: providing an aqueous-based insulating
fluid in an annulus between a tubing and a casing disposed
thereabout, the tubing and casing penetrating a subterranean
formation; and flowing steam through the tubing and into the
subterranean formation.
14. The method of claim 13, wherein providing comprises placing the
aqueous-based insulating fluid in the annulus, the aqueous-based
insulating fluid comprising an aqueous base fluid, a water-miscible
organic liquid, a synthetic polymer, and a crosslinker; and
crosslinking the synthetic polymer with the crosslinker.
15. The method of claim 14, wherein crosslinking comprises exposing
the aqueous-based insulating fluid to a temperature of about
90.degree. F. or greater.
16. The method of claim 13, wherein the aqueous-based insulating
fluid comprises an aqueous base fluid, a water-miscible organic
liquid, and a layered silicate.
17. The method of claim 13 further comprising: producing a
hydrocarbon fluid from the subterranean formation.
18. A method comprising: providing an aqueous-based insulating
fluid in an annulus between a tubing and a casing disposed
thereabout, the tubing and the casing penetrating a subterranean
formation, the subterranean formation comprising permafrost; and
flowing a fluid at about 40.degree. F. or greater through the
tubing.
19. The method of claim 18 further comprising: performing a
drilling operation to extend the wellbore in the subterranean
formation.
20. The method of claim 18, wherein providing comprises placing the
aqueous-based insulating fluid in the annulus, the aqueous-based
insulating fluid comprising an aqueous base fluid, a water-miscible
organic liquid, a synthetic polymer, and a crosslinker; and
crosslinking the synthetic polymer with the crosslinker.
21. The method of claim 18, wherein the aqueous-based insulating
fluid comprises an aqueous base fluid, a water-miscible organic
liquid, and a layered silicate.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation-in-part of U.S. patent
application Ser. No. 12/046,086, now published as 2008/0224087,
entitled "Improved Aqueous-Based Insulating Fluids and Related
Methods," filed on Mar. 11, 2008, which is a continuation-in-part
of U.S. patent application Ser. No. 11/685,909, now published as
2008/0227665, entitled "Improved Aqueous-Based Insulating Fluids
and Related Methods," filed on Mar. 14, 2007, the entirety of each
of these is incorporated herein by reference, and from which
priority is claimed pursuant to 35 U.S.C. .sctn.120.
BACKGROUND
[0002] The present invention relates to insulating fluids, and more
particularly, to aqueous-based insulating fluids that have greater
stability at high temperatures with lower thermal conductivity that
may be used, for example, in applications requiring an insulating
fluid such as pipeline and subterranean applications (e.g., to
insulate petroleum production conduits).
[0003] Insulating fluids are often used in subterranean operations
wherein the fluid is placed into an annulus between a first tubing
and a second tubing or the walls of a well bore. The insulating
fluid acts to insulate a first fluid (e.g., a hydrocarbon fluid)
that may be located within the first tubing from the environment
surrounding the first tubing or the second tubing to enable optimum
recovery of the hydrocarbon fluid. For instance, if the surrounding
environment is very cold, the insulating fluid is thought to
protect the first fluid in the first tubing from the environment so
that it can efficiently flow through the production tubing, e.g.,
the first tubing, to other facilities. This is desirable because
heat transfer can cause problems such as the precipitation of
heavier hydrocarbons, severe reductions in flow rate and, in some
cases, casing collapse. Additionally, when used in packer
applications, a required amount of hydrostatic head pressure is
needed. Thus, higher density insulating fluids are often used for
this reason as well to provide the requisite hydrostatic force.
[0004] Such fluids also may be used for similar applications
involving pipelines for similar purposes, e.g., to protect a fluid
located within the pipeline from the surrounding environmental
conditions so that the fluid can efficiently flow through the
pipeline. Insulating fluids can be used in other insulating
applications as well wherein it is desirable to control heat
transfer. These applications may or may not involve
hydrocarbons.
[0005] Beneficial insulating fluids preferably have a low inherent
thermal conductivity, and also should remain gelled to prevent,
inter alia, convection currents that could carry heat away.
Additionally, preferred insulating fluids should be aqueous-based,
and easy to handle and use. Moreover, preferred fluids should
tolerate ultra high temperatures (e.g., temperatures of 400.degree.
F. or above) for long periods of time for optimum performance.
[0006] Conventional aqueous-based insulating fluids have many
drawbacks. First, many have associated temperature limitations.
Typically, most aqueous-based insulating fluids are only stable up
to 240.degree. F. for relatively short periods of time. This can be
problematic because it can result in premature degradation of the
fluid, which can cause the fluid not to perform its desired
function with respect to insulating the first fluid. A second
common limitation of many conventional aqueous-based insulating
fluids is their density range. Typically, these fluids have an
upper density limit of 12.5 ppg. Oftentimes, higher densities are
desirable to maintain adequate pressure for the chosen application.
Additionally, most aqueous-based insulating fluids have excessive
thermal conductivities, which means that these fluids are not as
efficient or effective at controlling conductive heat transfer.
Moreover, when a viscosified fluid is required to eliminate
convective currents, oftentimes to obtain the required viscosity in
current aqueous-based fluids, the fluids may become too thick to be
able to pump into place. Some aqueous-based fluids also can have
different salt tolerances that may not be compatible with various
brines used, which limits the operators' options as to what fluids
to use in certain circumstances.
[0007] In some instances, insulating fluids may be oil-based.
Certain oil-based fluids may offer an advantage because they may
have lower thermal conductivity as compared to their aqueous
counterparts. However, many disadvantages are associated with these
fluids as well. First, oil-based insulating fluids can be hard to
"weight up," meaning that it may be hard to obtain the necessary
density required for an application. Secondly, oil-based fluids may
present toxicity and other environmental issues that should be
managed, especially when such fluids are used in sub-sea
applications. Additionally, there can be interface issues if
aqueous completion fluids are used. Another complication presented
when using oil-based insulating fluids is the concern about their
compatibility with any elastomeric seals that may be present along
the first tubing line.
[0008] Another method that may be employed to insulate a first
tubing involves using vacuum insulated tubing. However, this method
also can present disadvantages. First, when the vacuum tubing is
installed on a completion string, sections of the vacuum tubing can
fail. This can be a costly problem involving a lot of down time. In
severe cases, the first tubing can collapse. Secondly, vacuum
insulated tubing can be very costly and hard to place. Moreover, in
many instances, heat transfer at the junctions or connective joints
in the vacuum tubings can be problematic. These may lead to "hot
spots" in the tubings.
SUMMARY OF THE INVENTION
[0009] The present invention relates to insulating fluids, and more
particularly, to aqueous-based insulating fluids that have greater
stability at high temperatures with lower thermal conductivity that
may be used, for example, in applications requiring an insulating
fluid such as pipeline and subterranean applications (e.g., to
insulate petroleum production conduits).
[0010] In one embodiment, a method may include providing an
aqueous-based insulating fluid in an annulus between a riser column
and an outer casing disposed thereabout, the riser column
connecting a wellbore penetrating a subterranean formation to a
floating surface rig; and flowing a fluid through the riser column
and the wellbore.
[0011] In another embodiment, a method may include providing an
aqueous-based insulating fluid in an annulus between a tubing and a
casing disposed thereabout penetrating a subterranean formation;
and flowing steam through the tubing and into the subterranean
formation.
[0012] In yet another embodiment, a method may include providing an
aqueous-based insulating fluid in an annulus between a tubing and a
casing disposed thereabout penetrating a subterranean formation,
the subterranean formation comprising permafrost; and flowing a
fluid at about 40.degree. F. or greater through the tubing.
[0013] The features and advantages of the present invention will be
readily apparent to those skilled in the art upon a reading of the
description of the preferred embodiments that follows.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] The following figures are included to illustrate certain
aspects of the present invention, and should not be viewed as
exclusive embodiments. The subject matter disclosed is capable of
considerable modifications, alterations, combinations, and
equivalents in form and function, as will occur to those skilled in
the art and having the benefit of this disclosure.
[0015] FIG. 1 lists the materials used in the formulations and the
amounts thereof as described in Example 1 in the Examples
section.
[0016] FIG. 2 illustrates data from a fluid that was heated to
about 190.degree. F. for 5000 minutes to activate the crosslinking
agent and provide an increase in viscosity.
[0017] FIG. 3 lists the materials that may be used in the
formulations and the approximate amounts thereof as described in
Example 2 in the Examples section.
[0018] FIG. 4 illustrates data from a fluid that was heated from
approximately 100.degree. F. to approximately 600.degree. F. for
approximately 45,000 seconds at approximately 10,000 psi.
[0019] FIG. 5 provides a photograph of various insulating fluids
subjected to long-term, high-temperature conditions.
DETAILED DESCRIPTION
[0020] The present invention relates to insulating fluids, and more
particularly, to aqueous-based insulating fluids that have greater
stability at high temperatures with lower thermal conductivity that
may be used, for example, in applications requiring an insulating
fluid such as pipeline and subterranean applications (e.g., to
insulate petroleum production conduits). The aqueous-based
insulating fluids of the present invention may be used in any
application requiring an insulating fluid. Preferably, they may
have particular use in pipeline and subterranean applications.
[0021] The improved aqueous-based insulating fluids and methods of
the present invention have many potential advantages. One of these
many advantages is that the fluids, in some embodiments, may have
enhanced thermal stability, which enables them to be beneficially
used in many applications. Secondly, in some embodiments, the
aqueous-based insulating fluids of the present invention may have
higher densities than conventional aqueous-based insulating fluids,
and therefore, present a distinct advantage in that respect.
Additionally, the aqueous-based insulating fluids of the present
invention may have relatively low thermal conductivity, which is
thought to be especially beneficial in certain applications. In
some embodiments, these fluids are believed to be very durable.
Moreover, in some embodiments, the fluids of the present invention
offer aqueous-based viscous insulating fluids with a broad fluid
density range, decreased thermal conductivity, and stable gel
properties at temperatures exceeding those of current industry
standards (e.g., even at temperatures of about 600.degree. F. or
more, depending on the organic liquid included). Another potential
advantage is that these fluids may prevent the formation of
hydrates within the insulating fluids themselves or the fluids
being insulated. Other advantages and objects of the invention may
be apparent to one skilled in the art with the benefit of this
disclosure.
[0022] In certain embodiments, the aqueous-based insulating fluids
of the present invention comprise an aqueous base fluid, a
water-miscible organic liquid, and a layered silicate. In certain
embodiments, the aqueous-based insulating fluids of the present
invention comprise an aqueous base fluid, a water-miscible organic
liquid, a layered silicate, and optionally a synthetic polymer. In
some instances, the polymer may be crosslinked by using or adding
to the fluid an appropriate crosslinking agent. Thus, the term
"polymer" as used herein refers to oligomers, homopolymers,
copolymers, terpolymers and the like, which may or may not be
crosslinked. Optionally, the aqueous-based insulating fluids of the
present invention may comprise other additives such as corrosion
inhibitors, pH modifiers, biocides, glass beads, hollow spheres
(e.g., hollow microspheres), rheology modifiers, buffers, hydrate
inhibitors, breakers, tracers, additional weighting agents,
viscosifiers, surfactants, and combinations of any of these. Other
additives may be appropriate as well and beneficially used in
conjunction with the aqueous-based insulating fluids of the present
invention as may be recognized by one skilled in the art with the
benefit of this disclosure.
[0023] The aqueous base fluids that may be used in the
aqueous-based insulating fluids of the present invention include
any aqueous fluid suitable for use in insulating, subterranean, or
pipeline applications. In some instances, brines may be used, for
example, when a relatively denser aqueous-based insulating fluid is
desired (e.g., density of 10.5 ppg or greater); however, it may be
observed that the fluids of the present invention may be less
tolerant to higher concentrations of salts than other fluids, such
as those that include a polymer, but not a layered silicate as
described herein. Suitable brines include, but are not limited to
those that contain: NaCl, NaBr, KCl, CaCl.sub.2, CaBr.sub.2,
ZrBr.sub.2, sodium carbonate, sodium formate, potassium formate,
cesium formate, and combinations and derivatives of these brines.
Others may be appropriate as well. The specific brine used may be
dictated by the desired density of the resulting aqueous-based
insulating fluid or for compatibility with other completion fluid
brines that may be present. Denser brines may be useful in some
instances. A density that is suitable for the application at issue
should be used as recognized by one skilled in the art with the
benefit of this disclosure. When deciding how much of an aqueous
fluid to include, a general guideline to follow is that the aqueous
fluid component should comprise the balance of a high temperature
aqueous-based insulating fluid after considering the amount of the
other components present therein.
[0024] The water-miscible organic liquids that may be included in
the aqueous-based insulating fluids of the present invention
include water-miscible materials having relatively low thermal
conductivity (e.g., about half as conductive as water or less). By
"water-miscible," it is meant that about 5 grams or more of the
organic liquid will disperse in 100 grams of water. Suitable
water-miscible organic liquids include, but are not limited to,
esters, amines, alcohols, polyols, glycol ethers, or combinations
and derivatives of these. Examples of suitable esters include low
molecular weight esters; specific examples include, but are not
limited to, methylformate, methyl acetate, and ethyl acetate.
Combinations and derivatives are also suitable. Examples of
suitable amines include low molecular weight amines; specific
examples include, but are not limited to, diethyl amine,
2-aminoethanol, and 2-(dimethylamino)ethanol. Combinations and
derivatives are also suitable. Examples of suitable alcohols
include methanol, ethanol, propanol, isopropanol, and the like.
Combinations and derivatives are also suitable. Examples of glycol
ethers include ethylene glycol butyl ether, diethylene glycol
methyl ether, dipropylene glycol methyl ether, tripropylene glycol
methyl ether, and the like. Combinations and derivatives are also
suitable. Of these, polyols are generally preferred in most cases
over the other liquids since they generally are thought to exhibit
greater thermal and chemical stability, higher flash point values,
and are more benign with respect to elastomeric materials.
[0025] Suitable polyols are those aliphatic alcohols containing two
or more hydroxy groups. It is preferred that the polyol be at least
partially water-miscible.
[0026] Examples of suitable polyols that may be used in the
aqueous-based insulating fluids of this invention include, but are
not limited to, watersoluble diols such as ethylene glycols,
propylene glycols, polyethylene glycols, polypropylene glycols,
diethylene glycols, triethylene glycols, dipropylene glycols and
tripropylene glycols, combinations of these glycols, their
derivatives, and reaction products formed by reacting ethylene and
propylene oxide or polyethylene glycols and polypropylene glycols
with active hydrogen base compounds (e.g., polyalcohols,
polycarboxylic acids, polyamines, or polyphenols). The polyglycols
of ethylene generally are thought to be water miscible at molecular
weights at least as high as 20,000. The polyglycols of propylene,
although giving slightly better grinding efficiency than the
ethylene glycols, are thought to be water-miscible up to molecular
weights of only about 1,000. Other glycols possibly contemplated
include neopentyl glycol, pentanediols, butanediols, and such
unsaturated diols as butyne diols and butene diols. In addition to
the diols, the triol, glycerol, and such derivatives as ethylene or
propylene oxide adducts may be used. Other higher polyols may
include pentaerythritol. Another class of polyhydroxy alcohols
contemplated is the sugar alcohols. The sugar alcohols are obtained
by reduction of carbohydrates and differ greatly from the
above-mentioned polyols. Combinations and derivatives of these are
suitable as well.
[0027] The choice of polyol to be used is largely dependent on the
desired density of the fluid. Other factors to consider include
thermal conductivity. For higher density fluids (e.g., 10.5 ppg or
higher), a higher density polyol may be preferred, for instance,
triethylene glycol or glycerol may be desirable in some instances.
For lower density applications, ethylene or propylene glycol may be
used. In some instances, more salt may be necessary to adequately
weight the fluid to the desired density. In certain embodiments,
the amount of polyol that should be used may be governed by the
thermal conductivity ceiling of the fluid and the desired density
of the fluid. If the thermal conductivity ceiling is 0.17
BTU/hft.degree. F., then the concentration of the polyol may be
about 40% to about 99% of a high temperature aqueous-based
insulating fluid of the present invention. A more preferred range
could be about 70% to about 99%.
[0028] Examples of layered silicates that may be suitable for use
in the present invention include, but are not limited to, smectite,
vermiculite, swellable fluoromica, montmorillonite, beidellite,
hectorite, and saponite. A high-temperature, electrolyte stable
synthetic hectorite may be particularly useful in some embodiments.
An example of a synthetic hectorite clay for use in accordance with
this invention is LAPONITE.RTM. RD (commercially available from
Laporte Absorbents Company of Cheshire, United Kingdom). Mixtures
of any of these of silicates may be suitable as well. In preferred
embodiments, the silicate may be at least partially water soluble.
In some embodiments, the layered silicate may be a natural layered
silicate or a synthetic layered silicate. In certain embodiments,
the silicate should comprise about 0.1.degree./0 to about 15%
weight by volume of the fluid, and more preferably, about 0.5% to
about 4% weight by volume of the fluid.
[0029] Inclusion of a synthetic polymer may be useful, inter alia,
to produce fluids that exhibit gelation behavior. Examples of
synthetic polymers that optionally may be suitable for use in the
present invention include, but are not limited to, acrylic acid
polymers, acrylic acid ester polymers, acrylic acid derivative
polymers, acrylic acid homopolymers, acrylic acid ester
homopolymers (such as poly(methyl acrylate), poly (butyl acrylate),
and poly(2-ethylhexyl acrylate)), acrylic acid ester co-polymers,
methacrylic acid derivative polymers, methacrylic acid
homopolymers, methacrylic acid ester homopolymers (such as
poly(methyl methacrylate), polyacrylamide homopolymer, n-vinyl
pyrrolidone and polyacrylamide copolymers, poly(butyl
methacrylate), and poly (2-ethylhexyl methacrylate)), n-vinyl
pyrrolidone, acrylamido-methyl-propane sulfonate polymers,
acrylamidomethyl-propane sulfonate derivative polymers,
acrylamidomethyl-propane sulfonate co-polymers, and acrylic
acidlacrylamido-methyl-propane sulfonate copolymers, and
combinations thereof. Copolymers and terpolymers may be suitable as
well. Mixtures of any of these of polymers may be suitable as well.
In preferred embodiments, the polymer should be at least partially
water soluble. Suitable polymers can be cationic, anionic,
nonionic, or zwitterionic. In certain embodiments, the polymer
should comprise about 0.1% to about 15% weight by volume of the
fluid, and more preferably, about 0.5% to about 4%.
[0030] To obtain the desired gel characteristics and thermal
stability for an aqueous-based insulating fluid of the present
invention, the polymer included in the fluid may be crosslinked by
an appropriate crosslinking agent. In those embodiments of the
present invention wherein it is desirable to crosslink the polymer,
optionally and preferably, one or more crosslinking agents may be
added to the fluid to crosslink the polymer.
[0031] One type of suitable crosslinking agent is a combination of
a phenolic component (or a phenolic precursor) and formaldehyde (or
a formaldehyde precursor). Suitable phenolic components or phenolic
precursors include, but are not limited to, phenols, hydroquinone,
salicylic acid, salicylamide, aspirin, methyl-p-hydroxybenzoate,
phenyl acetate, phenyl salicylate, o-aminobenzoic acid,
p-aminobenzoic acid, m-aminophenol, furfuryl alcohol, and benzoic
acid. Suitable formaldehyde precursors may include, but are not
limited to, hexamethylenetetramine, glyoxal, and 1,3,5-trioxane.
This crosslinking agent system needs approximately 250.degree. F.
to thermally activate to crosslink the polymer. Another type of
suitable crosslinking agent is polyalkylimine. This crosslinking
agent needs approximately 90.degree. F. to activate to crosslink
the polymer. This crosslinking agent may be used alone or in
conjunction with any of the other crosslinking agents discussed
herein.
[0032] Another type of crosslinking agent that may be used includes
non-toxic organic crosslinking agents that are free from metal
ions. Examples of such organic cross-linking agents are
polyalkyleneimines (e.g., polyethyleneimine),
polyalkylenepolyamines and mixtures thereof. In addition,
water-soluble polyfunctional aliphatic amines, arylalkylamines and
heteroarylalkylamines may be utilized.
[0033] When included, suitable crosslinking agents may be present
in the fluids of the present invention in an amount sufficient to
provide, inter alia, the desired degree of crosslinking. In certain
embodiments, the crosslinking agent or agents may be present in the
fluids of the present invention in an amount in the range of about
0.0005% to about 10% weight by volume of the fluid. In certain
embodiments, the crosslinking agent may be present in the fluids of
the present invention in an amount in the range of about 0.001% to
about 5% weight by volume of the fluid. One of ordinary skill in
the art, with the benefit of this disclosure, will recognize the
appropriate amount of crosslinking agent to include in a fluid of
the present invention based on, among other things, the temperature
conditions of a particular application, the type of polymer(s)
used, the molecular weight of the polymer(s), the desired degree of
viscosification, and/or the pH of the fluid.
[0034] Although any suitable method for forming the insulating
fluids of the present invention may be used, in some embodiments,
an aqueous-based insulating fluid of the present invention may be
formulated at ambient temperature and pressure conditions by mixing
water and a chosen water-miscible organic liquid. The water and
water-miscible organic liquid preferably may be mixed so that the
water-miscible organic liquid is miscible in the water. The chosen
silicate may then be added and mixed into the water and
water-miscible organic liquid mixture until the silicate is
hydrated. Any chosen additives may be added at any point, including
a polymer. Preferably, any additives are dispersed within the
mixture. If desired, a crosslinking agent may be added. If used, it
should be dispersed in the mixture. Crosslinking, however,
generally should not take place until thermal activation, which
preferably, in subterranean applications, occurs downhole; this may
alleviate any pumping difficulties that might arise as a result of
activation before placement. Activation results in the fluid
forming a gel. The term "gel," as used herein, and its derivatives
refer to a semi-solid, jelly-like state assumed by some colloidal
dispersions. Once activated, the gel should stay in place and be
durable with negligible syneresis.
[0035] In some embodiments, the gels formed by hydrating the
silicate may have a zero sheer viscosity of about 100,000
centipoise measured on an Anton Paar Controlled Stress Rheometer at
standard conditions using standard operating procedures.
[0036] Once gelled, if the fluid contains polymer, one method of
minimizing or removing the gel may comprise diluting or breaking
the crosslinks and/or the polymer structure within the gel using an
appropriate method and/or composition to allow recovery or removal
of the gel. Another method could involve physical removal of the
gel by, for example, air or liquid.
[0037] In some embodiments, the aqueous-based insulating fluids of
the present invention may be prepared on-the-fly at a well-site or
pipeline location. In other embodiments, the aqueous-based
insulating fluids of the present invention may be prepared off-site
and transported to the site of use. In transporting the fluids, one
should be mindful of the activation temperature of the fluid.
[0038] In one embodiment, the present invention provides a method
comprising: providing a first tubing; providing a second tubing
that substantially surrounds the first tubing thus creating an
annulus between the first tubing and the second tubing; providing
an aqueous-based insulating fluid that comprises an aqueous base
fluid, a polyol, and a layered silicate; and placing the
aqueous-based insulating fluid in the annulus. In some embodiments,
the aqueous-based insulating fluid also includes a polymer. The
tubings may have any shape appropriate for a chosen application. In
some instances, the second tubing may not be the same length as the
first tubing. In some instances, the tubing may comprise a portion
of a larger apparatus. In some instances, the aqueous-based
insulating fluid may be in contact with the entire first tubing
from end to end, but in other situations, the aqueous-based
insulating fluid may only be placed in a portion of the annulus and
thus only contact a portion of the first tubing. In some instances,
the first tubing may be production tubing located within a well
bore. In some instances, the tubings may be located in a geothermal
well bore. The production tubing may be located in an off-shore
location. In other instances, the production tubing may be located
in a cold climate. In other instances, the first tubing may be a
pipeline capable of transporting a fluid from one location to a
second location.
[0039] In one embodiment, the present invention provides a method
comprising: providing a first tubing; providing a second tubing
that substantially surrounds the first tubing thus creating an
annulus between the first tubing and the second tubing; providing
an aqueous-based insulating fluid that comprises an aqueous base
fluid, a water-miscible organic liquid, and a layered silicate; and
placing the aqueous-based insulating fluid in the annulus. In some
embodiments, the aqueous-based insulating fluid also includes a
polymer.
[0040] In one embodiment, the present invention provides a method
comprising: providing a tubing containing a first fluid located
within a well bore such that an annulus is formed between the
tubing and a surface of the well bore; providing an aqueous-based
insulating fluid that comprises an aqueous base fluid, a
water-miscible organic liquid, and a layered silicate; and placing
the aqueous-based insulating fluid in the annulus. In some
embodiments, the aqueous-based insulating fluid also includes a
polymer.
[0041] In one embodiment, the present invention provides a method
comprising: providing a first tubing that comprises at least a
portion of a pipeline that contains a first fluid; providing a
second tubing that substantially surrounds the first tubing thus
creating an annulus between the first tubing and the second tubing;
providing an aqueous-based insulating fluid that comprises an
aqueous base fluid, a water-miscible organic liquid, and a layered
silicate; and placing the aqueous-based insulating fluid in the
annulus. In some embodiments, the aqueous-based insulating fluid
also includes a polymer.
[0042] In one embodiment, the present invention provides an
aqueous-based insulating fluid that comprises an aqueous base
fluid, a water-miscible organic liquid, and a layered silicate. In
some embodiments, the aqueous-based insulating fluid also includes
a polymer.
[0043] In another embodiment, the present invention provides a
method of forming an aqueous-based insulating fluid comprising:
mixing an aqueous base fluid and a water-miscible organic liquid to
form a mixture; adding at least one layered silicate to the
mixture; allowing the layered silicate to hydrate; placing the
mixture comprising the layered silicate in a chosen location; and
allowing the mixture comprising the layered silicate to activate to
form a gel therein. In some embodiments, a polymer may be added to
the mixture and allowed to hydrate. Optionally, a crosslinking
agent may be added to the mixture comprising the polymer to
crosslink the polymer.
[0044] In some embodiments, an aqueous-based insulating fluid
described herein may advantageously be utilized in subsea
applications, e.g., to mitigate thickening of fluids flowing
through a riser. In subsea applications, the subterranean formation
temperature is often significantly higher than that of the ocean,
especially in deep-water. Treatment fluids, e.g., drilling fluids,
are often designed to have specific rheological properties at the
temperatures of the subterranean formation. However, in subsea
applications, the reduced temperature of the ocean disposed about
the riser causes the treatment fluid to have different rheological
properties in the riser portion then in the wellbore portion.
Accordingly, many subterranean operations that are highly dependent
on the rheological properties of treatment fluids are unavailable
or very costly to be performed in subsea applications, e.g.,
managed pressure drilling operations and dual gradient operations.
Further, the rheological changes along the wellbore increase the
risk of damage to the formation or wellbore tools (e.g., the riser
or a blowout preventer), which can be reduced with the use of
high-stability insulating fluids.
[0045] The aqueous-based insulating fluids described herein may
advantageously be utilized, in some embodiments, in an annulus
disposed about the riser to mitigate fluid temperature reduction
associated with flowing through the riser. Surprisingly, it has
been observed that fluids passing through a riser insulated with
the aqueous-based insulating fluid described herein are about 20%
to about 40% warmer than without the insulting fluid. As such, the
rheological properties of the fluids are better controlled (e.g.,
mitigating yield point increases and minimizing the plastic
viscosity of the fluid), which in turn reduces the risk of pressure
spikes and lowers the equivalent circulating density ("ECD") of the
fluid. A lower ECD allows for a flatter rheological profile in a
narrow pore pressure-fracture pressure gradient window, thereby
mitigating formation damage during managed pressure drilling
operations.
[0046] Further, the aqueous-based insulating fluids described
herein are more stable than crosslinked biopolymer systems, thereby
reducing the frequency with which an insulating fluid would need to
be replace. In some instances, at least a portion of the
aqueous-based insulating fluid may exposed to a temperature of
about 30.degree. F. to about 400.degree. F. for 30 days or greater
without significant reduction in performance (e.g., thermal
conductivity). In some instances, at least a portion of the
aqueous-based insulating fluid may be exposed to a temperature of
about 250.degree. F. to about 400.degree. F. for 30 days or greater
without significant reduction in performance.
[0047] In some embodiments, the present invention provides a method
comprising: providing an aqueous-based insulating fluid in an
annulus between a riser column and an outer casing disposed
thereabout, the riser column connecting a wellbore penetrating a
subterranean formation to a floating surface rig; and flowing a
fluid through the riser column and the wellbore. In some
embodiments, the aqueous-based insulating fluid may comprise an
aqueous base fluid, a water-miscible organic liquid, and a
synthetic polymer crosslinked with a crosslinker. In some
embodiments, providing the aqueous-based insulating fluid in the
annulus may involve placing the aqueous-based fluid in the annulus,
the aqueous-based fluid comprising an aqueous base fluid, a water
miscible organic liquid, a synthetic polymer, and a crosslinker;
and crosslinking the synthetic polymer with the crosslinker. In
some instances, crosslinking may involve exposing the aqueous-based
insulating fluid to a temperature of about 90.degree. F. or
greater, which may occur before, after, or during placing the
aqueous-based insulating fluid in the annulus. In some embodiments,
the aqueous-based insulating fluid may comprise an aqueous base
fluid, a water-miscible organic liquid, a layered silicate, and
optionally a synthetic polymer, which may optionally be crosslinked
(e.g., via the crosslinking described above).
[0048] In some instances, the fluid passing through the riser may
be a drilling fluid, a formation fluid, or the like. In some
embodiments, methods may further involve performing a managed
pressure drilling operation to extend the wellbore in the
subterranean formation. In other embodiments, methods may further
involve performing a dual gradient drilling operation to extend the
wellbore in the subterranean formation.
[0049] In some instances, the aqueous-based insulating fluids
described herein may be utilized in conjunction with formations
having variable temperatures along the length of a wellbore,
especially in formations where near the surface the formation
comprises permafrost. Formations comprising permafrost are prone to
wellbore collapse when the fluids flowing therethrough are
sufficient to melt the permafrost. Further, the geographical
locations where formations comprising permafrost are located may
have additional environmental concerns and regulations. The ability
to minimize the local temperature changes for mitigating permafrost
melting may be advantageous in such locations.
[0050] Some embodiments of the present invention may involve
providing an aqueous-based insulating fluid in an annulus between a
tubing and an outer casing disposed thereabout; and flowing a fluid
at about 40.degree. F. or greater (e.g., about 40.degree. F. to
about 110.degree. F.) through the tubing. In some embodiments, the
aqueous-based insulating fluid may comprise an aqueous base fluid,
a water-miscible organic liquid, and a synthetic polymer
crosslinked with a crosslinker. In some embodiments, providing the
aqueous-based insulating fluid in the annulus may involve placing
the aqueous-based fluid in the annulus, the aqueous-based fluid
comprising an aqueous base fluid, a water miscible organic liquid,
a synthetic polymer, and a crosslinker; and crosslinking the
synthetic polymer with the crosslinker. In some instances,
crosslinking may involve exposing the aqueous-based insulating
fluid to a temperature of about 90.degree. F. or greater, which may
occur before, after, or during placing the aqueous-based insulating
fluid in the annulus. In some embodiments, the aqueous-based
insulating fluid may comprise an aqueous base fluid, a
water-miscible organic liquid, a layered silicate, and optionally a
synthetic polymer, which may optionally be crosslinked (e.g., via
the crosslinking described above).
[0051] In some instances, the fluid may be a drilling fluid, a
formation fluid, or the like. In some embodiments, methods may
further involve producing hydrocarbons from the subterranean
formation.
[0052] In some embodiments, the aqueous-based insulating fluids
described herein may be used in conjunction with other
high-temperature fluids, e.g., geothermal wells or steam injection
wells. The aqueous-based insulating fluids may advantageously
mitigate column expansion while enhancing the efficiency of the
wellbore operation because reduced heat loss of the
high-temperature fluid flowing therethrough. Column expansion can
lead to formation damage, column failure, and wellbore collapse.
Because of the high temperatures in steam injection wells,
crosslinked biopolymer systems tend to degrade and lose insulating
efficacy rapidly. The high-temperature stability of the
aqueous-based insulating fluids described herein (e.g., greater
than about 300.degree. F. or, in some instances, as high as
600.degree. F.) may advantageously mitigate the frequency with
which insulating fluids need to be replaced.
[0053] Some embodiments of the present invention may involve
providing an aqueous-based insulating fluid in an annulus between a
tubing and a casing string (e.g., a wellbore liner, a cement
casing, or the like), the aqueous-based insulating fluid comprising
an aqueous base fluid, a water-miscible organic liquid, and a
synthetic polymer crosslinked with a crosslinker; and flowing a
fluid at a temperature greater than about 225.degree. F. through
the tubing and into the subterranean formation. In some instances,
the fluid temperature may be from about 250.degree. F. to about
600.degree. F., depending on the application.
[0054] Some embodiments of the present invention may involve
providing an aqueous-based insulating fluid in an annulus between a
tubing and a casing disposed thereabout; and flowing steam through
the tubing and into the subterranean formation. In some
embodiments, the aqueous-based insulating fluid may comprise an
aqueous base fluid, a water-miscible organic liquid, and a
synthetic polymer crosslinked with a crosslinker. In some
embodiments, providing the aqueous-based insulating fluid in the
annulus may involve placing the aqueous-based fluid in the annulus,
the aqueous-based fluid comprising an aqueous base fluid, a water
miscible organic liquid, a synthetic polymer, and a crosslinker;
and crosslinking the synthetic polymer with the crosslinker. In
some instances, crosslinking may involve exposing the aqueous-based
insulating fluid to a temperature of about 90.degree. F. or
greater, which may occur before, after, or during placing the
aqueous-based insulating fluid in the annulus. In some embodiments,
the aqueous-based insulating fluid may comprise an aqueous base
fluid, a water-miscible organic liquid, a layered silicate, and
optionally a synthetic polymer, which may optionally be crosslinked
(e.g., via the crosslinking described above). Some embodiments may
further involve producing hydrocarbons from the subterranean
formation.
[0055] In some instances, the aqueous-based insulating fluid may be
utilized in the production well corresponding to a steam well.
Generally, the steam well is utilized for injecting steam, which
heats the heavy oil and reduces the viscosity. By utilizing
aqueous-based insulating fluids described herein in the production
wells, the heavy oil may advantageously retain the heat from the
steam and flow through the production well more easily and with
less energy input (e.g., lower pumping pressures).
[0056] Some embodiments of the present invention may involve
providing an aqueous-based insulating fluid in an annulus between a
tubing and a casing disposed thereabout within a production
wellbore; injecting steam into a subterranean formation comprising
heavy oil so as to yield heated heavy oil; and producing the heated
heavy oil via the production wellbore. In some embodiments, the
aqueous-based insulating fluid may comprise an aqueous base fluid,
a water-miscible organic liquid, and a synthetic polymer
crosslinked with a crosslinker. In some embodiments, providing the
aqueous-based insulating fluid in the annulus may involve placing
the aqueous-based fluid in the annulus, the aqueous-based fluid
comprising an aqueous base fluid, a water-miscible organic liquid,
a synthetic polymer, and a crosslinker; and crosslinking the
synthetic polymer with the crosslinker. In some instances,
crosslinking may involve exposing the aqueous-based insulating
fluid to a temperature of about 90.degree. F. or greater, which may
occur before, after, or during placing the aqueous-based insulating
fluid in the annulus. In some embodiments, the aqueous-based
insulating fluid may comprise an aqueous base fluid, a
water-miscible organic liquid, a layered silicate, and optionally a
synthetic polymer, which may optionally be crosslinked (e.g., via
the crosslinking described above).
[0057] In some instances, the aqueous-based fluids described herein
may be used to prevent damage to cemented casings. Cement casings
are prone to cracking, degrading, forming microannuli, and the like
with thermal fluctuation that are often a consequence of performing
a plurality of wellbore operations. Such degradation, e.g.,
especially microannuli, inhibit zonal isolation and well control,
which, in some instances, can lead to wellbore blowouts,
contamination of isolated water tables, and the like.
[0058] Some embodiments of the present invention may involve
providing an aqueous-based insulating fluid in an annulus between a
pipe (or liner or the like) and a cement casing disposed
thereabout; and flowing a fluid through the pipe. In some
embodiments, the aqueous-based insulating fluid may comprise an
aqueous base fluid, a water-miscible organic liquid, and a
synthetic polymer crosslinked with a crosslinker. In some
embodiments, providing the aqueous-based insulating fluid in the
annulus may involve placing the aqueous-based fluid in the annulus,
the aqueous-based fluid comprising an aqueous base fluid, a water
miscible organic liquid, a synthetic polymer, and a crosslinker;
and crosslinking the synthetic polymer with the crosslinker. In
some instances, crosslinking may involve exposing the aqueous-based
insulating fluid to a temperature of about 90.degree. F. or
greater, which may occur before, after, or during placing the
aqueous-based insulating fluid in the annulus. In some embodiments,
the aqueous-based insulating fluid may comprise an aqueous base
fluid, a water-miscible organic liquid, a layered silicate, and
optionally a synthetic polymer, which may optionally be crosslinked
(e.g., via the crosslinking described above).
[0059] In some embodiments, the methods described herein may
utilize aqueous-based insulating fluid with water-miscible organic
liquid that comprise an amine, e.g., diethyl amine, 2-aminoethanol,
and 2-(dimethylamino)ethanol, and the like, and any combination
thereof.
[0060] In some embodiments, the methods described herein may
utilize an aqueous-based insulating fluid (or crosslinked synthetic
polymer) with a crosslinker that comprises at least one of
polyalkylimine, polyalkyleneimines, polyethyleneimine, and the
like, any derivative thereof, and any combination thereof.
[0061] In some embodiments, the methods described herein may
utilize an aqueous-based insulating fluid in an environment (e.g.,
in an annulus, in a pipeline, in a wellbore, and the like) such
that at least a portion of the aqueous-based insulating fluid is
exposed to temperatures of about 300.degree. F. or greater, about
350.degree. F. or greater, or about 400.degree. F. or greater
(e.g., about 400.degree. F. to about 600.degree. F.). For example,
at least one side of an annulus may be at such a temperature.
[0062] In some embodiments, the methods described herein may
utilize an aqueous-based insulating fluid in an environment (e.g.,
in an annulus, in a pipeline, in a wellbore, and the like) that has
a temperature differential across the aqueous-based insulating
fluid of about 50.degree. F. or greater, about 100.degree. F. or
greater, or about 150.degree. F. or greater (e.g., about 50.degree.
F. to about 200.degree. F.). In some embodiments, the methods
described herein may utilize an aqueous-based insulating fluid in
an environment (e.g., in an annulus, in a pipeline, in a wellbore,
and the like) that has a temperature differential across the
aqueous-based insulating fluid having less than about 1 in
thickness (e.g., the inner portion of the annulus being about 1/8
in to about 1 in thick) of about 50.degree. F. or greater, about
100.degree. F. or greater, or about 150.degree. F. or greater
(e.g., about 50.degree. F. to about 200.degree. F.).
[0063] To facilitate a better understanding of the present
invention, the following examples of preferred or representative
embodiments are given. In no way should the following examples be
read to limit, or to define, the scope of the invention.
EXAMPLES
Example 1
[0064] We studied the formulation and testing of various
combinations of inorganic, organic, clay and polymeric materials
for use as viscosifying/gelling agents in aqueous based fluids for
insulating fluids. We conducted a series of tests in which the
solubility, thermal conductivity, thermal stability, pH, gelling
properties, rheological behavior, and toxicity of the various
fluids were evaluated and compared. Perhaps most importantly, the
thermal stability ranges from 37.degree. F. to 280.degree. F. and
above were evaluated. These tests were conducted over short and
long term periods. FIG. 1 lists the materials used in the
formulations and the amounts tested. This in no way should be
construed as an exhaustive example with reference to the invention
or as a definition of the invention in any way.
[0065] Thermal stability and static aging: All formulations of
fluids were statically aged at temperatures about
.gtoreq.280.degree. F. for two months. Formulations and properties
for the tested fluids are shown in Tables 1 and 2 below. Most of
the fluids appeared to remain intact, with the crosslinked systems
showing an increase in viscosity and what appeared to be complete
gelation behavior. We believe that these systems appeared to
exhibit more desirable stability properties than other fluids,
which included numerous biopolymers (e.g., xanthan, welan, and
diutan gums) and inorganic clays and were generally destroyed after
3 days at 250.degree. F. In addition, as to the thermal stability
of these formulations tested, less than 1% syneresis was observed
for any of the samples.
[0066] In addition to the static tests, Sample 4 was evaluated
using a high-temperature viscometer to examine the thermal
activation of crosslinking agents (FIG. 2). The fluid was subjected
to a low shear rate at 190.degree. F., with viscosity measurements
showing an increase with time to reach the maximum recordable level
around 5000 minutes.
TABLE-US-00001 TABLE 1 IPF Formulations and Properties Before
Static Aging Sample 1 2 3 4 Formulations Density, ppg 8.5 10.5 12.3
11.3 Water, % vol 20 10 -- 1 Glycerol, % vol -- 90 78.5 90 PG, %
vol 80 -- -- -- Brine, % vol -- -- 21.5 9 Polymer A, % wt 1 1 1 --
Polymer B, % wt -- -- -- 1.25 Aldehyde, ppm 5000 5000 5000 -- HQ,
ppm 5000 5000 5000 -- PEI, % wt -- -- -- 2 Properties 300 rpm.sup.1
280 285 270 82 Shear Strength, lb/100 ft.sup.2 13.4 20.65 20.65
>13.4 Thermal Conductivity.sup.2, 0.141 0.172 0.154 0.158
BTU/hft .degree. F. .sup.1Measurements obtained from reading
observed on Fann 35 viscometer, sample temperature 120.degree. F.
.sup.2Measurements obtained by KD2-Pro Thermal Properties
Analyzer.
TABLE-US-00002 TABLE 2 IPF Formulations and Properties After 60
Days Static Aging at 280.degree. F. Sample 1 2 3 4 Formulations
Density, ppg 8.5 10.5 12.3 11.3 Water, % vol 20 10 -- 1 Glycerol, %
vol -- 90 78.5 90 PG, % vol 80 -- -- -- Brine, % vol -- -- 21.5 9
Polymer A, % wt 1 1 1 -- Polymer B, % wt -- -- -- 1.25 Aldehyde,
ppm 5000 5000 5000 -- HQ, ppm 5000 5000 5000 -- PEI, % wt -- -- --
2 Properties 300 rpm.sup.3 max max max max Shear Strength, lb/100
ft.sup.2 >50 >50 >50 >50 Thermal Conductivity.sup.2,
0.141 0.172 0.154 0.158 BTU/hft .degree. F. .sup.3Fluids gelled,
off-scale measurement.
[0067] Thermal conductivity measurements: The importance of a low
thermal conductivity (K) is an important aspect of the success of
insulating fluids. For effective reduction of heat transfer,
aqueous-based packer fluids in the density range of 8.5 to 12.3 ppg
are expected to exhibit values for K of 0.3 to 0.2 BTU/hr ft
.degree. F., and preferably would have lower values. From the
various formulations listed above, fluid densities of 8.5 to 14.4
ppg were observed, all of which have a thermal conductivity of
<0.2 BTU/hr ft .degree. F. as shown in Tables 1 and 2.
Example 2
[0068] We studied the formulation and testing of various
combinations of inorganic, organic, clay and polymeric materials
for use as viscosifying/gelling agents in aqueous based fluids for
insulating fluids. We conducted a series of tests in which the
solubility, thermal conductivity, thermal stability, pH, gelling
properties, rheological behavior, and toxicity of the various
fluids were evaluated and compared. Perhaps most importantly, the
thermal stability ranges from 37.degree. F. to 500.degree. F. and
above were evaluated. These tests were conducted over short and
long term periods. FIG. 3 lists the materials used in the
formulations and the amounts tested. This in no way should be
construed as an exhaustive example with reference to the invention
or as a definition of the invention in any way.
[0069] Thermal stability and static aging: All formulations of
fluids were statically aged at temperatures about 400.degree. F.
for 3 day intervals. Formulations and properties for the tested
fluids are shown in Tables 3 and 4 below. Most of the fluids
appeared to remain intact, with the crosslinked systems showing an
increase in viscosity and what appeared to be complete gelation
behavior. We believe that these systems appeared to exhibit more
desirable stability properties than other fluids, which included
numerous biopolymers (e.g., xanthan, welan, and diutan gums) and
inorganic clays and were generally destroyed after 3 days at
250.degree. F. In addition, as to the thermal stability of these
formulations tested, less than 1% syneresis was observed for any of
the samples.
TABLE-US-00003 TABLE 3 IPF Formulations and Properties Before
Static Aging Sample 1 2 Thermal conductivity, BTU/(hft .degree. F.)
0.166 0.177 Density, lb/gal 10.5 9.5 Fann .RTM. 35 Viscometer
150.degree. F. 150.degree. F. 600 rpm 160 161 300 rpm 125 126 200
rpm 109 102 100 rpm 84 88 6 rpm 37 40 3 rpm 34 38 PV 35 35 YP 90
91
TABLE-US-00004 TABLE 4 IPF Formulations and Properties After 72
Hours Static Aging at 450.degree. F. Sample 1 2 Thermal
conductivity, BTU/(hft .degree. F.) 0.166 0.177 Density, lb/gal
10.5 9.5 Fann .RTM. 35 Viscometer 150.degree. F. 150.degree. F. 600
rpm 163 159 300 rpm 127 122 200 rpm 111 104 100 rpm 82 86 6 rpm 40
41 3 rpm 36 37 PV 36 35 YP 91 85
[0070] Thermal conductivity measurements: The importance of a low
thermal conductivity (K) is an important aspect of the success of
insulating fluids. For effective reduction of heat transfer,
aqueous-based packer fluids in the density range of 8.5 to 10.5 ppg
are expected to exhibit values for K of 0.3 to 0.2 BTU/hr ft
.degree. F., and preferably would have lower values. From the
various formulations listed above, fluid densities of 8.5 to 10.5
ppg were observed, all of which have a thermal conductivity of
<0.2 BTU/hr ft .degree. F. as shown in Tables 3 and 4.
Example 3
[0071] In a wellbore in the field, a casing was determined to be
poorly bonded to the tubing. As such, when steam was injected into
the wellbore, the casing expanded, and because of poor adhesion to
the tubing, extended out of the wellbore by about as much as 11
feet. When an aqueous-based insulating fluid described herein was
placed between the casing and the tubing, the tubing extended out
only about 3 feet. Further, with the aqueous-based insulating
fluid, the steam injection operation was able to run longer with
higher injection rates.
Example 4
[0072] In a deviated wellbore in the field with a casing well
bonded to the tubing, the wellbore was utilized for a steam
assisted gravity drainage operation. Because of the good bonding
between the tubing and the casing, the tubing twists and breaks
because of differential casing and tubing expansion. When an
aqueous-based insulating fluid described herein was placed between
the tubing and a tubing disposed therein, the twist-off was
mitigated, and possibly eliminated.
Example 5
[0073] Three different biopolymer systems optionally crosslinked
with multivalent ions (Sample A--crosslinked guar, Sample B--a
xanthan diuten blend, and Sample C--crosslinked xanthan) and one
sample of an aqueous-based insulating fluid according to the
present invention (Sample D--polyacrylamide crosslinked with
polyethylene imine) were tested at 300.degree. F. for 30 days. FIG.
5 provides a photograph of the four samples after aging. The
biopolymer samples A, B, and C all showed phase separation and
varying degrees of polymer degradation indicated by charring and
discoloration. Sample A has completely charred, which in
application in a subterranean operation could be catastrophic.
Sample B has significant charring, and Sample C has moderate
charring. The degradation seen in all three samples lead to reduced
viscosity and lost gelation, which, in turn, allows for convective
currents to form that increase the heat transfer properties of the
fluid, i.e., the fluid no longer functions as an insulating fluid.
In contrast, Sample D of an aqueous-based insulating fluid
described herein shows no phase separation and no degradation.
Rather, Sample D is a clear single-phase fluid. This example
illustrates the thermal stability of the aqueous-based insulating
fluid of the present invention.
[0074] The exemplary aqueous-based insulating fluids disclosed
herein may directly or indirectly affect one or more components or
pieces of equipment associated with the preparation, delivery,
recapture, recycling, reuse, and/or disposal of the disclosed
aqueous-based insulating fluids. For example, the disclosed
aqueous-based insulating fluids may directly or indirectly affect
one or more mixers, related mixing equipment, mud pits, storage
facilities or units, fluid separators, heat exchangers, sensors,
gauges, pumps, compressors, and the like used generate, store,
monitor, regulate, and/or recondition the exemplary aqueous-based
insulating fluids. The disclosed aqueous-based insulating fluids
may also directly or indirectly affect any transport or delivery
equipment used to convey the aqueous-based insulating fluids to a
well site or downhole such as, for example, any transport vessels,
conduits, pipelines, trucks, tubulars, and/or pipes used to
fluidically move the aqueous-based insulating fluids from one
location to another, any pumps, compressors, or motors (e.g.,
topside or downhole) used to drive the aqueous-based insulating
fluids into motion, any valves or related joints used to regulate
the pressure or flow rate of the aqueous-based insulating fluids,
and any sensors (i.e., pressure and temperature), gauges, and/or
combinations thereof, and the like. The disclosed aqueous-based
insulating fluids may also directly or indirectly affect the
various downhole equipment and tools that may come into contact
with the aqueous-based insulating fluids such as, but not limited
to, drill string, coiled tubing, drill pipe, drill collars, mud
motors, downhole motors and/or pumps, floats, MWD/LWD tools and
related telemetry equipment, drill bits (including roller cone,
PDC, natural diamond, hole openers, reamers, and coring bits),
sensors or distributed sensors, downhole heat exchangers, valves
and corresponding actuation devices, tool seals, packers and other
wellbore isolation devices or components, and the like.
[0075] Therefore, the present invention is well adapted to attain
the ends and advantages mentioned as well as those that are
inherent therein. The particular embodiments disclosed above are
illustrative only, as the present invention may be modified and
practiced in different but equivalent manners apparent to those
skilled in the art having the benefit of the teachings herein.
Furthermore, no limitations are intended to the details of
construction or design herein shown, other than as described in the
claims below. It is therefore evident that the particular
illustrative embodiments disclosed above may be altered, combined,
or modified and all such variations are considered within the scope
and spirit of the present invention. The invention illustratively
disclosed herein suitably may be practiced in the absence of any
element that is not specifically disclosed herein and/or any
optional element disclosed herein. While compositions and methods
are described in terms of "comprising," "containing," or
"including" various components or steps, the compositions and
methods can also "consist essentially of" or "consist of" the
various components and steps. All numbers and ranges disclosed
above may vary by some amount. Whenever a numerical range with a
lower limit and an upper limit is disclosed, any number and any
included range falling within the range is specifically disclosed.
In particular, every range of values (of the form, "about a to
about b," or, equivalently, "from approximately a to b," or,
equivalently, "from approximately a-b") disclosed herein is to be
understood to set forth every number and range encompassed within
the broader range of values. Also, the terms in the claims have
their plain, ordinary meaning unless otherwise explicitly and
clearly defined by the patentee. Moreover, the indefinite articles
"a" or "an," as used in the claims, are defined herein to mean one
or more than one of the element that it introduces. If there is any
conflict in the usages of a word or term in this specification and
one or more patent or other documents that may be incorporated
herein by reference, the definitions that are consistent with this
specification should be adopted.
* * * * *