U.S. patent application number 11/482601 was filed with the patent office on 2008-01-10 for methods and compositions for enhancing proppant pack conductivity and strength.
This patent application is currently assigned to Halliburton Energy Services, Inc.. Invention is credited to Philip D. Nguyen, Richard D. Rickman.
Application Number | 20080006405 11/482601 |
Document ID | / |
Family ID | 38918144 |
Filed Date | 2008-01-10 |
United States Patent
Application |
20080006405 |
Kind Code |
A1 |
Rickman; Richard D. ; et
al. |
January 10, 2008 |
Methods and compositions for enhancing proppant pack conductivity
and strength
Abstract
Methods comprising providing a curable resin composition that
comprises a curable resin and at least a plurality of filler
particles; and coating at least a plurality of particulates with
the curable resin composition on-the-fly to form curable resin
coated particulates. The curable resin coated particulates may be
suspended in a treatment fluid and placed into at least a portion
of a subterranean formation.
Inventors: |
Rickman; Richard D.;
(Duncan, OK) ; Nguyen; Philip D.; (Duncan,
OK) |
Correspondence
Address: |
ROBERT A. KENT
P.O. BOX 1431
DUNCAN
OK
73536
US
|
Assignee: |
Halliburton Energy Services,
Inc.
|
Family ID: |
38918144 |
Appl. No.: |
11/482601 |
Filed: |
July 6, 2006 |
Current U.S.
Class: |
166/295 ;
166/305.1; 507/219 |
Current CPC
Class: |
C09K 8/805 20130101 |
Class at
Publication: |
166/295 ;
166/305.1; 507/219 |
International
Class: |
E21B 33/138 20060101
E21B033/138 |
Claims
1. A method comprising: providing at least a plurality of
particulates; providing a curable resin composition comprising a
curable resin and at least a plurality of filler particles; coating
the particulates with the curable resin composition on-the-fly to
form curable resin coated particulates; suspending the curable
resin coated particulates in a treatment fluid; and placing the
treatment fluid into at least a portion of a subterranean
formation.
2. The method of claim 1 wherein the filler particles comprise at
least one filler particle selected from the group consisting of
silica, glass, clay, alumina, fumed carbon, carbon black, graphite,
mica, meta-silicate, calcium silicate, calcine, kaoline, talc,
zirconia, titanium dioxide, fly ash, boron, and any combination
thereof.
3. The method of claim 1 wherein the size of the filler particles
is from about 0.01 .mu.m to about 100 .mu.m.
4. The method of claim 1 wherein the curable resin comprises at
least one curable resin selected from the group consisting of a two
component epoxy based resin, a novolak resin, a polyepoxide resin,
a phenol aldehyde resin, a urea aldehyde resin, a urethane resin, a
phenolic resin, a furan resin, a furan/furfuryl alcohol resin, a
phenolic/latex resin, a phenol formaldehyde resin, a polyester
resin and any hybrid or copolymer thereof, a polyurethane resin and
any hybrid or copolymer thereof, an acrylate resin, and any
combination thereof.
5. The method of claim 1 wherein the curable resin composition is
coated on the curable resin coated particulates in an amount in the
range of from about 0.1% to about 25% by weight of the
particulates.
6. The method of claim 1 wherein the filler particles are included
in the curable resin composition in an amount in the range of from
about 1% to about 70% by weight of the curable resin
composition.
7. A method comprising: providing a curable resin composition that
comprises a curable resin and at least a plurality of filler
particles; and coating at least a plurality of particulates with
the curable resin composition on-the-fly to form curable resin
coated particulates.
8. The method of claim 7 further comprising the steps of suspending
the curable resin coated particulates in a treatment fluid and
placing the treatment fluid into at least a portion of a
subterranean formation.
9. The method of claim 7 wherein the filler particles comprise at
least one filler particle selected from the group consisting of
silica, glass, clay, alumina, fumed carbon, carbon black, graphite,
mica, meta-silicate, calcium silicate, calcine, kaoline, talc,
zirconia, titanium dioxide, fly ash, boron, and an y combination
thereof.
10. The method of claim 7 wherein the size of the filler particles
is from about 0.01 .mu.m to about 100 .mu.m.
11. The method of claim 7 wherein the curable resin comprises at
least one curable resin is selected from the group consisting of a
two component epoxy based resin, a novolak resin, a polyepoxide
resin, a phenol aldehyde resin, a urea aldehyde resin, a urethane
resin, a phenolic resin, a furan resin, a furan/furfuryl alcohol
resin, a phenolic/latex resin, a phenol formaldehyde resin, a
polyester resin and any hybrid or copolymer thereof, a polyurethane
resin and any hybrid or copolymer thereof, an acrylate resin, and
any combination thereof.
12. The method of claim 7 wherein the curable resin composition is
coated on the curable resin coated particulates in an amount in the
range of from about 0.1% to about 25% by weight of the
particulates.
13. The method of claim 7 wherein the filler particles are included
in the curable resin composition in an amount in the range of from
about 1% to about 70% by weight of the curable resin
composition.
14. A method comprising: providing a curable resin and at least a
plurality of filler particles; combining the curable resin and the
filler particles at the well site to form a curable resin
composition; and coating at least a plurality of particulates with
the curable resin composition on-the-fly to form curable resin
coated particulates.
15. The method of claim 14 further comprising the steps of
suspending the curable resin coated particulates in a treatment
fluid and placing the treatment fluid into at least a portion of a
subterranean formation.
16. The method of claim 14 wherein the filler particles comprise at
least one particle selected from the group consisting of silica,
glass, clay, alumina, fumed carbon, carbon black, graphite, mica,
meta-silicate, calcium silicate, calcine, kaoline, talc, zirconia,
titanium dioxide, fly ash, boron, and an y combination thereof.
17. The method of claim 14 wherein the size of the filler particles
is from about 0.01 .mu.m to about 100 .mu.m.
18. The method of claim 14 wherein the curable resin is comprises
at least one curable resin selected from the group consisting of a
two component epoxy based resin, a novolak resin, a polyepoxide
resin, a phenol aldehyde resin, a urea aldehyde resin, a urethane
resin, a phenolic resin, a furan resin, a furan/furfuryl alcohol
resin, a phenolic/latex resin, a phenol formaldehyde resin, a
polyester resin and any hybrid or copolymer thereof, a polyurethane
resin and any hybrid or copolymer thereof, an acrylate resin, and
any combination thereof.
19. The method of claim 14 wherein the curable resin composition is
coated on the curable resin coated particulates in an amount in the
range of from about 0.1% to about 25% by weight of the
particulates.
20. The method of claim 14 wherein the filler particles are
included in the curable resin composition in an amount in the range
of from about 1% to about 70% by weight of the curable resin
composition.
Description
BACKGROUND
[0001] The present invention relates to the treatment of
subterranean formations. More particularly, the present invention
relates to methods and compositions for enhancing proppant pack
conductivity and strength.
[0002] Hydrocarbon-producing wells are often stimulated by
hydraulic fracturing treatments. Hydraulic fracturing operations
generally involve pumping a treatment fluid (e.g., a fracturing
fluid or a "pad" fluid) into a well bore that penetrates a
subterranean formation at a hydraulic pressure sufficient to create
or enhance at least one or more fractures in the subterranean
formation. The fluid used in the treatment may comprise
particulates, which are often referred to as "proppant
particulates," that are deposited in the resultant fractures. The
proppant particulates are thought to prevent the fractures from
fully closing upon the release of hydraulic pressure, forming
conductive channels through which fluids may flow to a well bore to
ultimately be produced. The term "propped fracture" as used herein
refers to a fracture (naturally-occurring or otherwise) in a
portion of a subterranean formation that contains at least a
plurality of proppant particulates. The term "proppant pack" refers
to a collection of proppant particulates within a fracture.
[0003] Hydrocarbon-producing wells also may undergo gravel packing
treatments, inter alia, to reduce the migration of unconsolidated
formation particulates into the well bore. In gravel packing
operations, particulates, often referred to in the art as gravel,
are suspended in a treatment fluid, which may be viscosified, and
the treatment fluid is pumped into a well bore in which the gravel
pack is to be placed. As the particulates are placed in or near a
subterranean zone, the treatment fluid is either returned to the
surface or leaks off into the zone. The resultant gravel pack acts
as a filter to prevent the production of the formation solids with
the produced fluids. Traditional gravel pack operations may involve
placing a gravel pack screen in the well bore and then packing the
surrounding annulus between the screen and the well bore with
gravel. The gravel pack screen is generally a filter assembly used
to support and retain the gravel placed during the gravel pack
operation. A wide range of sizes and screen configurations is
available to suit the characteristics of a well bore, the
production fluid, and any particulates in the subterranean
formation.
[0004] In some situations, hydraulic fracturing and gravel packing
operations may be combined into a single treatment. Such treatments
are often referred to as "frac pack" operations. In some cases, the
treatments are generally completed with a gravel pack screen
assembly in place with the hydraulic fracturing treatment being
pumped through the annular space between the casing and screen. In
this situation, the hydraulic fracturing treatment ends in a
screen-out condition, creating an annular gravel pack between the
screen and casing. In other cases, the fracturing treatment may be
performed prior to installing the screen and placing a gravel
pack.
[0005] Particulates (such as proppant or gravel) used in
subterranean operations are often coated with resins to facilitate
consolidation of the particulates and/or to prevent their
subsequent flow-back through the conductive channels in the
subterranean formation, which can, for example, clog the conductive
channels and/or damage the interior of the formation or equipment.
The term "resin" as used herein refers to any of numerous
physically similar polymerized synthetics or chemically modified
natural resins including thermoplastic materials and thermosetting
materials.
[0006] Generally, resin coated proppants are either precured or
curable. Precured resin coated proppants comprise a proppant coated
with a resin that has been significantly crosslinked. This precured
resin coating provides crush resistance to the proppant. The resin
coating is already cured before it is introduced into the well and
therefore, the proppant does not agglomerate. However, in some
instances, precured proppants may flow back from a propped
fracture, especially during clean up or production in oil and gas
wells, because they are mainly held in the fracture by stress.
[0007] In contrast, curable resin coated proppants comprise a
proppant coated with a resin which has not been significantly
crosslinked before being placed in a subterranean formation.
Curable resins include (i) resins which are cured entirely in the
subterranean formation and (ii) resins which are partially cured
prior to injection into the subterranean formation with the
remainder of curing occurring in the subterranean formation. Curing
occurs as a result of the crosslinking of the resin, which may
occur as a result of the stress and temperature conditions existing
in the subterranean formation, and/or as a result of an activator
and/or catalyst. This is believed to cause the proppant to bond
together and form a 3-dimensional matrix and thereby prevent
proppant flow-back. However, curable resins may be expensive.
Therefore, any filler medium that can be admixed with a resin
composition to enhance the consolidation performance of coating on
particulates, allowing a reduced amount of resin coating on
proppant, is economically desirable.
SUMMARY
[0008] The present invention relates to the treatment of
subterranean formations. More particularly, the present invention
relates to methods and compositions for enhancing proppant pack
conductivity and strength.
[0009] One embodiment of the present invention is a method
comprising: providing at least a plurality of particulates;
providing a curable resin composition comprising a curable resin
and at least a plurality of filler particles; coating the
particulates with the curable resin composition on-the-fly to form
curable resin coated particulates; suspending the curable resin
coated particulates in a treatment fluid; and placing the treatment
fluid into at least a portion of a subterranean formation.
[0010] Another embodiment of the present invention is a method
comprising: providing a curable resin composition that comprises a
curable resin and at least a plurality of filler particles; and
coating at least a plurality of particulates with the curable resin
composition on-the-fly.
[0011] Another embodiment of the present invention is a method
comprising: providing a curable resin and at least a plurality of
filler particles; combining the curable resin and the filler
particles at the well site to form a curable resin composition; and
coating at least a plurality of particulates with the curable resin
composition on-the-fly.
[0012] The features and advantages of the present invention will be
apparent to those skilled in the art. While numerous changes may be
made by those skilled in the art, such changes are within the
spirit of the invention.
DESCRIPTION OF PREFERRED EMBODIMENTS
[0013] The present invention relates to the treatment of
subterranean formations. More particularly, the present invention
relates to methods and compositions for enhancing proppant pack
conductivity and strength.
[0014] In accordance with the methods and compositions of the
present invention, at least a plurality of particulates may be at
least partially coated with a curable resin composition that
comprises a curable resin and at least a plurality of filler
particles. These particulates may be referred to herein as "coated
particulates." In some embodiments, these coated particulates may
be used, inter alia, to facilitate the consolidation of the
particulates into a permeable mass that may improve the resiliency,
crush resistance, and/or conductivity of a resulting particulate
pack. Additionally, in some embodiments, these coated particulates
may be 100% curable within the subterranean formation, so as to
form a permeable mass of high compressive strength. The term
"coated" as used herein does not imply any particular degree of
coverage of the particulates with a curable resin composition.
[0015] In certain embodiments, the particulates may be coated with
the curable resin composition in an amount of from about 0.1% to
about 25% by weight of the particulates. In other embodiments,
particulates may be coated with the curable resin composition in an
amount of from about 1% to about 5% by weight of the
particulates.
[0016] The particulates may be coated by any suitable method as
recognized by one skilled in the art with the benefit of this
disclosure. In some embodiments, the particulates may be coated
with the curable resin composition on-the-fly and then introduced
into a subterranean formation. As used herein, the term
"on-the-fly" is used to mean that a flowing stream is continuously
introduced into another flowing stream so that the streams are
combined and mixed while continuing to flow as a single stream as
part of an on-going treatment. Some potential advantages that may
be achieved by coating particulates with the curable resin
composition on-the-fly is that the amount or type of filler
particles included in the curable resin composition may be adjusted
immediately prior to the proppants being coated and introduced into
the formation.
[0017] In certain embodiments, the coated particulates may be
suspended in a treatment fluid and this treatment fluid may be
placed into a subterranean formation. The coated particulates may
be suspended in the treatment fluid by any suitable method as
recognized by one skilled in the art with the benefit of this
disclosure.
[0018] A wide variety of particulate materials may be used in
accordance with the present invention, including, but not limited
to, sand, bauxite, ceramic materials, glass materials, resin
precoated proppant (e.g., commercially available from Borden
Chemicals and Santrol, for example, both from Houston, Tex.),
polymer materials, "TEFLON.TM." (tetrafluoroethylene) materials,
nut shells, ground or crushed nut shells, seed shells, ground or
crushed seed shells, fruit pit pieces, ground or crushed fruit
pits, processed wood, composite particulates prepared from a binder
with filler particulate including silica, alumina, fumed silica,
carbon black, graphite, mica, titanium dioxide, meta-silicate,
calcium silicate, kaolin, talc, zirconia, boron, fly ash, hollow
glass microspheres, and solid glass; or mixtures thereof. The
particulate material used may have a particle size in the range of
from about 2 to about 400 mesh, U.S. Sieve Series. Preferably, the
particulate material is graded sand having a particle size in the
range of from about 10 to about 70 mesh, U.S. Sieve Series.
Preferred sand particle size distribution ranges are one or more of
10-20 mesh, 20-40 mesh, 40-60 mesh or 50-70 mesh, depending on the
particle size and distribution of the formation particulates to be
screened out by the particulate materials. It should be understood
that the term "particulate," as used in this disclosure, includes
all known shapes of materials including substantially spherical
materials, fibrous materials, polygonal materials (such as cubic
materials) and mixtures thereof. It should also be understood that
the term "proppant," as used in this disclosure, includes all known
shapes of materials including substantially spherical materials,
fibrous materials, polygonal materials (such as cubic materials)
and mixtures thereof.
[0019] Curable resins suitable for use in the methods and
compositions of the present invention include any resin that is
capable of forming a hardened, consolidated mass. The term "resin"
as used herein includes any of numerous physically similar
polymerized synthetics or chemically modified natural resins,
including but not limited to thermoplastic materials and
thermosetting materials. Many such resins are commonly used in
subterranean consolidation operations, and some suitable resins
include two component epoxy based resins, novolak resins,
polyepoxide resins, phenol-aldehyde resins, urea-aldehyde resins,
urethane resins, phenolic resins, furan resins, furan/furfuryl
alcohol resins, phenolic/latex resins, phenol formaldehyde resins,
polyester resins and hybrids and copolymers thereof, polyurethane
resins and hybrids and copolymers thereof, acrylate resins, and
mixtures thereof. Some suitable resins, such as epoxy resins, may
be cured with an internal catalyst or activator so that when pumped
downhole, they may be cured using only time and temperature. Other
suitable resins, such as furan resins generally require a
time-delayed catalyst or an external catalyst to help activate the
polymerization of the resins if the cure temperature is low (i.e.,
less than 250.degree. F.) but will cure under the effect of time
and temperature if the formation temperature is above about
250.degree. F., preferably above about 300.degree. F. It is within
the ability of one skilled in the art, with the benefit of this
disclosure, to select a suitable resin for use in embodiments of
the present invention and to determine whether a catalyst is
required to trigger curing.
[0020] Selection of a suitable curable resin may be affected by the
temperature of the subterranean formation to which the fluid will
be introduced. By way of example, for subterranean formations
having a bottom hole static temperature ("BHST") ranging from about
60.degree. F. to about 250.degree. F., two component epoxy based
resins comprising a hardenable resin component and a hardening
agent component containing specific hardening agents may be
preferred. For subterranean formations having a BHST ranging from
about 300.degree. F. to about 600.degree. F., a furan based resin
may be preferred. For subterranean formations having a BHST ranging
from about 200.degree. F. to about 400.degree. F., either a
phenolic based resin or a one component HT epoxy based resin may be
suitable. For subterranean formations having a BHST of at least
about 175.degree. F., a phenol/phenol formaldehyde/furfuryl alcohol
resin may also be suitable.
[0021] Any solvent that is compatible with the chosen resin and
achieves the desired viscosity effect is suitable for use in the
present invention. Some preferred solvents are those having high
flash points (e.g., about 125.degree. F.) because of, among other
things, environmental and safety concerns; such solvents include
butyl lactate, butylglycidyl ether, dipropylene glycol methyl
ether, dipropylene glycol dimethyl ether, dimethyl formamide,
diethyleneglycol methyl ether, ethyleneglycol butyl ether,
diethyleneglycol butyl ether, propylene carbonate, methanol, butyl
alcohol, d-limonene, fatty acid methyl esters, and combinations
thereof. Other preferred solvents include aqueous dissolvable
solvents such as, methanol, isopropanol, butanol, glycol ether
solvents, and combinations thereof. Suitable glycol ether solvents
include, but are not limited to, diethylene glycol methyl ether,
dipropylene glycol methyl ether, 2-butoxy ethanol, ethers of a
C.sub.2 to C.sub.6 dihydric alkanol containing at least one C.sub.1
to C.sub.6 alkyl group, mono ethers of dihydric alkanols,
methoxypropanol, butoxyethanol, hexoxyethanol, and isomers thereof.
Selection of an appropriate solvent is dependent on the resin
chosen and is within the ability of one skilled in the art with the
benefit of this disclosure.
[0022] Suitable filler particles for use in the present invention
include any particle that does not adversely react with the other
components used in accordance with this invention or with the
subterranean formation. Examples of suitable filler particles
include silica, glass, clay, alumina, fumed silica, carbon black,
graphite, mica, meta-silicate, calcium silicate, calcine, kaoline,
talc, zirconia, titanium dioxide, fly ash, boron, and combinations
thereof. In some embodiments, the filler particles may range in
size from about 0.01 .mu.m to about 100 .mu.m. As will be
understood by one skilled in the art, particles of smaller average
size may be particularly useful in situations where it is desirable
to obtain high proppant pack permeability (i.e., conductivity),
and/or high consolidation strength. In certain embodiments, the
filler particles may be included in the curable resin compositions
of the present invention in an amount of about 1% to about 70% by
weight of the curable resin composition.
[0023] Generally, the filler particles may be admixed with a resin
by any suitable method as recognized by one skilled in the art with
the benefit of this disclosure. In some embodiments of the present
invention, the filler particles may be admixed with the curable
resin well in advance of the curable resin composition being coated
onto particulates to be introduced into a subterranean formation,
creating a curable resin composition that may be used at some time
in the future. In other embodiments, the filler particles may be
admixed with the curable resin at the well site.
[0024] In certain embodiments, the particulates may be at least
partially coated with the curable resin composition and introduced
into a treatment fluid, which acts as the aqueous medium, directly
prior to being introduced into a subterranean formation in an
on-the-fly treatment. For instance, the curable resin composition
coated particulates may be mixed with an aqueous liquid (such as a
treatment fluid) on-the-fly to form a treatment slurry. Such mixing
can also be described as "real-time" mixing. One advantage of using
on-the-fly mixing in the methods of the present invention is that
it may allow for reduced waste in the event the treatment needs to
be immediately shut down. As is well understood by those skilled in
the art, mixing may also be accomplished by batch or partial batch
mixing.
[0025] Generally, any treatment fluid suitable for a subterranean
operation may be used in accordance with the methods of the present
invention, including aqueous gels, viscoelastic surfactant gels,
foamed gels and emulsions. Suitable aqueous gels are generally
comprised of water and one or more gelling agents. Suitable
emulsions can be comprised of two immiscible liquids such as an
aqueous liquid or gelled liquid and a hydrocarbon. Foams can be
created by the addition of a gas, such as carbon dioxide or
nitrogen. In certain embodiments of the present invention, the
treatment fluids are aqueous gels comprised of water, a gelling
agent for gelling the water and increasing its viscosity, and,
optionally, a crosslinking agent for crosslinking the gel and
further increasing the viscosity of the fluid. The increased
viscosity of the gelled, or gelled and cross-linked, treatment
fluid, inter alia, reduces fluid loss and allows the treatment
fluid to transport significant quantities of suspended
particulates. The water used to form the treatment fluid may be
fresh water, salt water, brine, sea water, or any other aqueous
liquid that does not adversely react with the other components. The
density of the water can be increased to provide additional
particle transport and suspension in the present invention.
[0026] A variety of gelling agents may be used, including
hydratable polymers that contain one or more functional groups such
as hydroxyl, carboxyl, sulfate, sulfonate, amino, or amide groups.
Suitable gelling agents typically comprise polymers, synthetic
polymers, or a combination thereof. A variety of gelling agents may
be used in conjunction with the methods of the present invention,
including, but not limited to, hydratable polymers that contain one
or more functional groups such as hydroxyl, cis-hydroxyl,
carboxylic acids, derivatives of carboxylic acids, sulfate,
sulfonate, phosphate, phosphonate, amino, or amide. In some
embodiments, the gelling agents may be polymers comprising
polysaccharides, and derivatives thereof that contain one or more
of these monosaccharide units: galactose, mannose, glucoside,
glucose, xylose, arabinose, fructose, glucuronic acid, or pyranosyl
sulfate. Examples of suitable polymers include, but are not limited
to, guar gum and derivatives thereof, such as hydroxypropyl guar
and carboxymethylhydroxypropyl guar, and cellulose derivatives,
such as hydroxyethyl cellulose. Additionally, synthetic polymers
and copolymers that contain the above-mentioned functional groups
may be used. Examples of such synthetic polymers include, but are
not limited to, polyacrylate, polymethacrylate, polyacrylamide,
polyvinyl alcohol, and polyvinylpyrrolidone. In other embodiments,
the gelling agent molecule may be depolymerized. The term
"depolymerized," as used herein, generally refers to a decrease in
the molecular weight of the gelling agent molecule. Depolymerized
gelling agent molecules are described in U.S. Pat. No. 6,488,091
issued Dec. 3, 2002 to Weaver, et al., the relevant disclosure of
which is incorporated herein by reference. Suitable gelling agents
that may be used in conjunction with the methods of the present
invention may be present in the treatment fluid in an amount in the
range of from about 0.01% to about 5% by weight of the water
therein. In some embodiments, the gelling agents may be present in
the treatment fluid in an amount in the range of from about 0.01%
to about 2% by weight of the water therein.
[0027] Crosslinking agents may be used to crosslink gelling agent
molecules to form crosslinked gelling agents. Crosslinkers
typically comprise at least one metal ion that is capable of
crosslinking molecules. Examples of suitable crosslinkers include,
but are not limited to, zirconium compounds (such as, for example,
zirconium lactate, zirconium lactate triethanolamine, zirconium
acetylacetonate, zirconium citrate, and zirconium diisopropylamine
lactate); titanium compounds (such as, for example, titanium
lactate, titanium citrate, titanium ammonium lactate, titanium
triethanolamine, and titanium acetylacetonate); aluminum compounds
(such as, for example, aluminum lactate or aluminum citrate);
antimony compounds; chromium compounds; iron compounds; copper
compounds; zinc compounds; or a combination thereof. An example of
a suitable commercially available zirconium-based crosslinker is
"CL-24" available from Halliburton Energy Services, Inc., Duncan,
Okla. An example of a suitable commercially available
titanium-based crosslinker is "CL-39" available from Halliburton
Energy Services, Inc., Duncan, Okla. Suitable crosslinkers that may
be used in conjunction with the methods of the present invention
may be present in the treatment fluid in an amount sufficient to
provide, inter alia, the desired degree of crosslinking between
gelling agent molecules. In some embodiments of the present
invention, the crosslinkers may be present in the treatment fluid
in an amount in the range from about 0.001% to about 10% by weight
of the water therein. In other embodiments of the present
invention, the crosslinkers may be present in the treatment fluid
in an amount in the range from about 0.01% to about 1% by weight of
the water therein. Individuals skilled in the art, with the benefit
of this disclosure, will recognize the exact type and amount of
crosslinker to use depending on factors such as the specific
gelling agent, desired viscosity, and formation conditions.
[0028] The gelled or gelled and cross-linked treatment fluids may
also include internal delayed gel breakers such as enzyme,
oxidizing, acid buffer, or temperature-activated gel breakers. The
gel breakers cause the viscous treatment fluids to revert to thin
fluids that can be produced back to the surface after they have
been used to place particulates in subterranean fractures. The gel
breaker used is typically present in the treatment fluid in an
amount in the range of from about 0.05% to about 10% by weight of
the gelling agent. The treatment fluids may also include one or
more of a variety of well-known additives, such as gel stabilizers,
fluid loss control additives, clay stabilizers, bactericides, and
the like.
[0029] To facilitate a better understanding of the present
invention, the following examples of certain aspects of some
embodiments are given. In no way should the following examples be
read to limit, or define, the entire scope of the invention.
Example 1
[0030] Consolidation strength testing was performed using a
commercially available curable resin available under the trade name
"EXPEDITE 225" from Halliburton Energy Services. Sample portions of
equal volumes of 20/40 Brady sand were each coated with 3% of the
curable resin composition containing variable amounts of silica
flour as the filler particles. Sample 1 was the control and did not
contain any silica flour. Sample 2 contained 5% silica flour.
Sample 3 contained 10% silica flour. Sample 4 contained 20% silica
flour. Sample 5 contained 40% silica flour.
[0031] The resulting unconfined compressive strengths of the
proppant are given below in Table 1. TABLE-US-00001 TABLE 1
Compressive Strength Sample % Silica Flour (psi) 1 0 1664 2 5 1546
3 10 1215 4 20 1526 5 40 1096
[0032] From Table 1, it is evident that the resin-treated proppants
achieve unconfined compressive strengths.
Example 2
[0033] Consolidation strength testing was performed using a
commercially available curable resin available under the trade name
"EXPEDITE 225" from Halliburton Energy Services. In addition to
filler particulates, a silane coupling agent was added to the
curable resin composition. Sample portions of equal volumes of
20/40 Brady sand were each coated with 3% of the curable resin
composition containing 40% silica flour, and variable amounts of a
silane coupling agent. Sample 1 contained 1% of the silane coupling
agent. Sample 2 contained 2% of the silane coupling agent. Sample 3
contained 4% of the silane coupling agent. Sample 4 contained 6% of
the silane coupling agent was added.
[0034] The resulting unconfined compressive strengths of the
proppant are given below in Table 2 TABLE-US-00002 TABLE 2 % Silane
Coupling Compressive Strength Sample Agent (psi) 1 1 1096 2 2 966 3
4 1886 4 6 1462
[0035] From Table 2, it is evident that the resin-treated proppants
achieve unconfined compressive strengths.
[0036] 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.
While numerous changes may be made by those skilled in the art,
such changes are encompassed within the spirit of this invention as
defined by the appended claims. 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 or modified and all such variations are
considered within the scope and spirit of the present invention. In
particular, every range of values (e.g., "from about a to about b,"
or, equivalently, "from approximately a to b," or, equivalently,
"from approximately a-b") disclosed herein is to be understood as
referring to the power set (the set of all subsets) of the
respective range of values. The terms in the claims have their
plain, ordinary meaning unless otherwise explicitly and clearly
defined by the patentee.
* * * * *