U.S. patent application number 11/244559 was filed with the patent office on 2007-04-12 for methods for enhancing aqueous fluid recovery form subterranean formations.
This patent application is currently assigned to Halliburton Energy Services, Inc.. Invention is credited to Bobby Bowles, Philip D. Nguyen, Mark A. Parker, Billy F. Slabaugh, Jimmie D. Weaver.
Application Number | 20070079965 11/244559 |
Document ID | / |
Family ID | 37434036 |
Filed Date | 2007-04-12 |
United States Patent
Application |
20070079965 |
Kind Code |
A1 |
Nguyen; Philip D. ; et
al. |
April 12, 2007 |
Methods for enhancing aqueous fluid recovery form subterranean
formations
Abstract
Methods of improving load recovery using hydrophobic coatings to
enhance the recovery of treatment fluids from subterranean
formations may include the use of hydrophobic coating agents. In
particular, such methods may include the steps of coating a
plurality of particulates so as to form a plurality of
hydrophobically-coated particulates. The presence of these
hydrophobically-coated particulates downhole may enhance the
recovery of aqueous treatment fluids.
Inventors: |
Nguyen; Philip D.; (Duncan,
OK) ; Weaver; Jimmie D.; (Duncan, OK) ;
Bowles; Bobby; (Comanche, OK) ; Slabaugh; Billy
F.; (Marlow, OK) ; Parker; Mark A.; (Duncan,
OK) |
Correspondence
Address: |
Robert A. Kent;Halliburton Energy Services, Inc.
2600 S. 2nd Street
Duncan
OK
73536-0440
US
|
Assignee: |
Halliburton Energy Services,
Inc.
|
Family ID: |
37434036 |
Appl. No.: |
11/244559 |
Filed: |
October 6, 2005 |
Current U.S.
Class: |
166/279 ;
166/305.1; 507/269; 507/901 |
Current CPC
Class: |
C09K 8/805 20130101;
C09K 8/68 20130101 |
Class at
Publication: |
166/279 ;
166/305.1; 507/269; 507/901 |
International
Class: |
E21B 43/16 20060101
E21B043/16 |
Claims
1. A method of enhancing the recovery of an aqueous treatment fluid
from a subterranean formation comprising: providing a plurality of
particulates; coating the plurality of particulates with a
hydrophobic coating agent so as to form a plurality of
hydrophobically-coated particulates; providing a carrier fluid;
mixing the plurality of hydrophobically-coated particulates with
the carrier fluid so as to form a pumpable slurry; introducing the
plurality of hydrophobically-coated particulates into the
subterranean formation; placing the plurality of
hydrophobically-coated particulates in the subterranean formation;
and allowing a treatment fluid to flow back through the plurality
of hydrophobically-coated particulates to recover a treatment fluid
that was previously-introduced into the subterranean formation.
2. The method of claim 1 wherein the hydrophobic coating agent
comprises a polyamide.
3. The method of claim 1 wherein the hydrophobic coating agent is a
polycarbonate, a polycarbamate, or a natural resin.
4. The method of claim 1 wherein the hydrophobic coating agent
comprises a reaction product of a compound having a chlorosilyl
group and an alkysilane.
5. The method of claim 1 wherein the hydrophobic coating agent
comprises a polymer of a silane compound having a
fluoroalkyl-group.
6. The method of claim 1 wherein the hydrophobic coating agent is a
silicon-oxide layer, a hybrid organo-silicon oxide anchor layer, or
a mixture thereof.
7. The method of claim 6 further comprising coating a
chloroalkysilane by vapor-deposition on the surface of the
hydrophobically-coated particulates
8. The method of claim 1 wherein the hydrophobic coating agent
comprises a polymer of a fluoroalkyl-group containing silane
compound.
9. The method of claim 1 wherein the hydrophobic coating agent
comprises lecithin.
10. The method of claim 3 wherein the coating of the plurality of
particulates occurs before the mixing of the plurality of
hydrophobically-coated particulates with the carrier fluid.
11. The method of claim 1 wherein the hydrophobic coating agent
comprises a polyamide, a solvent, and a surfactant.
12. The method of claim 11 wherein the surfactant is lauryl
sulfate, a polycarbonate, a polyacetal, a poly(orthoester), a
polyesteramide, or an alkyl sulfate having an alkyl chain from
about 6 carbon atoms to about 21 carbon atoms.
13. The method of claim 11 wherein the solvent comprises isopropyl
alcohol.
14. The method of claim 11 wherein the surfactant comprises
cocodiamine.
15. The method of claim 14 wherein the solvent comprises isopropyl
alcohol.
16. A method of enhancing the recovery of an aqueous treatment
fluid from a subterranean formation comprising: providing a
plurality of hydrophobically-coated particulates; placing the
plurality of hydrophobically-coated particulates in the
subterranean formation; and allowing a treatment fluid to flow back
through the plurality of hydrophobically-coated particulates to
recover a treatment fluid that was previously-introduced into the
subterranean formation.
17. The method of claim 16 wherein the hydrophobic coating agent
comprises a polyamide.
18. The method of claim 17 wherein the hydrophobic coating agent
further comprises an solvent wherein the solvent is isopropyl
alcohol and a surfactant.
19. A method of recovering a previously-introduced aqueous
treatment fluid from a subterranean formation comprising: providing
a plurality of particulates; introducing the plurality of
particulates into a subterranean well bore; introducing a
hydrophobic coating agent into the subterranean well bore; allowing
the hydrophobic coating agent to coat the plurality of particulates
so as to form a plurality of hydrophobically-coated particulates;
allowing the plurality of hydrophobically-coated particulates to be
placed in a portion of the subterranean formation; and allowing the
previously-introduced aqueous treatment fluid to flow back through
the plurality of hydrophobically-coated particulates.
20. The method of claim 16 wherein the hydrophobic coating agent
comprises a polyamide, a solvent wherein the solvent is isopropyl
alcohol, and a surfactant wherein the surfactant is cocodiamine.
Description
BACKGROUND
[0001] The present invention relates to the enhancement of
treatment fluid recovery from subterranean formations. More
particularly, the present invention relates to improved methods
using hydrophobic coating agents to enhance the recovery of aqueous
treatment fluids.
[0002] Treatment fluids are often used in a variety of subterranean
formations. Such treatments include, but are not limited to,
drilling operations, stimulation treatments, completion fluids, and
sand control treatments. As used herein, the term "treatment," or
"treating," refers to any subterranean operation that uses a fluid
in conjunction with a desired function and/or for a desired
purpose. The term "treatment" or "treating" does not necessarily
imply any particular action by the fluid.
[0003] Recovery of an aqueous treatment fluid is often desired
after the treatment fluid has performed its function. Typically,
treatment fluids, such as fracturing fluids, for example, will be
recovered by allowing the treatment fluid to flow back from the
subterranean formation. Increasing the efficiency and the recovery
rate of aqueous treatment fluids, sometimes referred to as load
recovery, is often desired. As used herein, the term "load
recovery" means the recovery of an aqueous treatment fluid
previously-injected into a subterranean formation. Increasing load
recovery is often desired, because the continued presence of an
aqueous treatment fluid can undesirably reduce hydrocarbon
production. That is, an increase in water saturation in the
near-well bore area can result in water blocks that may act to
impair the production of hydrocarbons. As used herein, the term
"water block" refers to the reduction of formation permeability
caused by the invasion or saturation of water into the pores
causing capillary blocking of pore throats by surface tension
and/or clay swelling. Treatment fluids, and more particularly,
aqueous treatment fluids that remain in the near well bore area can
impede the migration of hydrocarbons into and through the pore
spaces of the treated region.
[0004] Enhancing the recovery of treatments fluids such as
fracturing fluids may also be desirable to allow, in some cases,
the possible reuse of the treatment fluid or to avoid excessive
mixing of the treatment fluid with produced hydrocarbons.
[0005] Although usually no additional action is taken to enhance
the load recovery efficiency beyond merely flowing back from the
formation, some conventional methods used to increase the recovery
of a treatment fluid have included certain chemical treatments such
as the use of surfactants to decrease water wetting of the
formation. Reducing water wetting of the formation is thought to
increase the relative permeability of water in the formation so as
to enhance, at least temporarily, the load recovery from the
subterranean formation. Other methods have been used to increase
load recovery such as enhanced cleanup of propped fractures.
Unfortunately, the conventional methods often suffer from high cost
and/or low efficiencies.
[0006] Despite past advances in load recovery efficiency, further
improving load recovery efficiencies may be advantageous. For
example, gas production may be enhanced in certain applications by
improvement of load recovery by, among other things, improvement in
the removal of water blocks.
SUMMARY
[0007] The present invention relates to the enhancement of
treatment fluid recovery from subterranean formations. More
particularly, the present invention relates to improved methods
using hydrophobic coating agents to enhance the recovery of aqueous
treatment fluids.
[0008] One embodiment of the present invention provides a method of
enhancing the recovery of an aqueous fluid from a subterranean
formation comprising: providing a plurality of particulates;
coating the plurality of particulates with a hydrophobic coating
agent so as to form a plurality of hydrophobically-coated
particulates; providing a carrier fluid; mixing the plurality of
hydrophobically-coated particulates with the carrier fluid so as to
form a pumpable slurry; introducing the plurality of
hydrophobically-coated particulates into the subterranean
formation; placing the plurality of hydrophobically-coated
particulates in the subterranean formation; and allowing a
treatment fluid to flow back through the plurality of
hydrophobically-coated particulates to recover a treatment fluid
that was previously-introduced into the subterranean formation.
[0009] Another embodiment of the present invention provides a
method of recovering a previously-introduced aqueous treatment
fluid from a subterranean formation comprising: providing a
plurality of particulates; introducing the plurality of
particulates into a subterranean well bore; introducing a
hydrophobic coating agent into the subterranean well bore; allowing
the hydrophobic coating agent to coat the plurality of particulates
so as to form a plurality of hydrophobically-coated particulates;
allowing the plurality of hydrophobically-coated particulates to be
placed in a portion of the subterranean formation; and allowing the
previously-introduced aqueous treatment fluid to flow back through
the plurality of hydrophobically-coated particulates.
[0010] Another embodiment of the present invention provides method
of enhancing the recovery of an aqueous treatment fluid from a
subterranean formation comprising: providing a plurality of
hydrophobically-coated particulates; placing the plurality of
hydrophobically-coated particulates in the subterranean formation;
and allowing a treatment fluid to flow back through the plurality
of hydrophobically-coated particulates to recover a treatment fluid
that was previously-introduced into the subterranean formation.
[0011] 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
[0012] The present invention relates to the enhancement of
treatment fluid recovery from subterranean formations. More
particularly, the present invention relates to improved methods
using hydrophobic coating agents to increase the recovery of
aqueous treatment fluids.
[0013] Improving the load recovery of treatment fluids is often
desirable to enhance the production of hydrocarbons, in part, by
the removal of water blocks. The methods and compositions of the
present invention allow for an enhanced recovery of treatment
fluids from subterranean formations both in terms of rate and
efficiency. In preferred embodiments, the methods and compositions
of the present invention are especially suited for enhancing the
recovery of aqueous fracturing fluids from subterranean
formations.
[0014] Methods of the present invention may include coating
proppant or gravel particulates with a hydrophobic or
water-repellent coating. A fracturing carrier fluid may be used to
introduce coated particulates into created fractures in the
subterranean formation. By introducing coated proppant or coated
gravel particulates into the subterranean formation and allowing
the treatment fluids to flow back through the coated particulates,
the recovery of the aqueous treatment fluids may be enhanced.
I. Hydrophobically-Coated Particulates Used in Conjuction with the
Present Invention
[0015] A. Suitable Particulates
[0016] The particulates that may be used in the present invention
include any proppant or gravel particulates that may be used in a
subterranean application (proppant and gravel particulates are
referred to herein collectively as "particulates"). Suitable
particulates include sand, sintered bauxite, silica alumina, glass
beads, etc. Other suitable particulates include, but are not
limited to, sand, bauxite, ceramic materials, glass materials,
polymer materials, polytetrafluoroethylene materials, nut shell
pieces, seed shell pieces, fruit pit pieces, wood, composite
particulates, proppant particulates, gravel, and combinations
thereof. Suitable composite materials may comprise a binder and a
filler material wherein suitable filler materials include silica,
alumina, fumed carbon, carbon black, graphite, mica, titanium
dioxide, meta-silicate, calcium silicate, kaolin, talc, zirconia,
boron, fly ash, hollow glass microspheres, solid glass, and
combinations thereof. In certain exemplary embodiments, the
particulates may comprise common sand. Suitable particulates may
take any shape including, but not limited to, the physical shape of
platelets, shavings, flakes, ribbons, rods, strips, spheroids,
ellipsoids, toroids, pellets, or tablets. Although a variety of
particulate sizes may be useful in the present invention, in
certain embodiments, particulate sizes greater than about 100 mesh
are preferred, and in still other embodiments, particulate sizes
greater than about 40 mesh is preferred.
[0017] B. Hydrophobic Coatings Generally
[0018] The hydrophobically-coated particulates used in the methods
of the present invention may comprise a plurality of particulates
and a hydrophobic coating. Optionally, the hydrophobically-coated
particulates may comprise a surfactant.
[0019] Particulates of the present invention may be coated with a
hydrophobic or water repellant coating. The term "coating" as used
herein refers to at least a partial coating of some or all of the
particulates. 100% coverage of the particulates is not implied by
the term "coating." Hydrophobic coating agents of the present
invention may be any chemical agent capable of forming a
hydrophobic coating on the surface of particulates so as to enhance
the recovery of an aqueous treatment fluid. In certain embodiments,
a surfactant may be included in the hydrophobic coating agent so as
to improve the coating process as explained further below. Suitable
hydrophobic coating agents may include oligomeric materials,
monomeric materials, and oil-wetting compounds to provide at least
a monomolecular film making the mineral surfaces water-repellent or
hydrophobic.
[0020] In one embodiment, the particulate solids may be coated with
certain resin compositions or tackifying agents so as to provide a
hydrophobic coating on their surfaces as explained in more detail
below. In another embodiment, the hydrophobic surface coating may
comprise the reaction products of a compound having a chlorosilyl
group and an alkylsilane. The hydrophobic coatings may be formed by
forming a silicon oxide layer or hybrid organo-silicon oxide anchor
layer from a humidified reaction product of silicon tetrachloride
or trichloromethysilane, followed by the vapor-deposition of a
chloroalkylsilane.
[0021] In another embodiment, the hydrophobic coating agent may
comprise polymers of a fluoroalkyl-group containing silane
compound, and the polymers may include at least dimers and trimers
of the silane compound. This hydrophobic coating agent may be made
by preparing a hydrophobic solution, the solution being produced by
subjecting a fluoroalkyl-group contained silane compound to a
hydrolysis and a condensation polymerization to produce at least
dimers and trimers of the silane compound, coating the hydrophobic
solution onto the surface of the particulate solids, and heating
the particulate solids to cause the fluoroalkyl group in the
solution to be bonded to the surface of the particulate solids so
as to form the hydrophobic film on the particulate solids.
[0022] In another embodiment, the hydrophobic coating agent may
comprise lecithin. Lecithin is particularly suitable for this
purpose, because it creates a monomolecular film and is
hydrophobic. Lecithin is a phosphorus-containing liquid, that is, a
phosphatide found in all living organisms, both plant and animal.
It consists of glycerol combined with two fatty acid radicals,
phosphoric acid and choline. Hence, there may be many lecithin or
phosphatidylcholines depending on the nature and disposition of the
fatty acid groups. The term "lecithin" as used herein includes
natural, synthetic, and modified lecithins, and it may be
chemically or enzymatically modified. For more information on
lecithin and its many variants, please see the KIRK-OTHMER
ENCYCLOPEDIA OF CHEMICAL TECHNOLOGY, 4th ed. Volume 15, pages
192-210, John Wiley & Sons, 1995. Lecithins Sources,
Manufacture & Uses, by Bernard F. Szuhaj, AMERICAN OIL CHEMISTS
SOCIETY, 1985 and Lecithins, by Bernard F. Szuhaj and Gary R. List,
AMERICAN OIL CHEMISTS SOCIETY, 1985.
[0023] In yet another embodiment, the hydrophobic coating agent may
comprise a polyamide. Without being limited to a particular
molecular weight range, in certain embodiments, the hydrophobic
coating agent may include polyamides having molecular weights from
about 10,000 to about 200,000.
[0024] Other hydrophobic coating agents are described in U.S. Pat.
Nos. 5,249,627 issued to Harms et al. and 6,660,693 issued to
Miller et al., which are incorporated herein by reference.
[0025] In certain preferred embodiments, the hydrophobic coating
agent may comprise a polyamide, isopropyl alcohol, and a
cocodiamene surfactant.
[0026] C. Surfactants That May Be Optionally Included in the
Hydrophobic Coating Agents of the Present Invention
[0027] In certain embodiments, the hydrophobic coating agent may
optionally further comprise a surfactant. Any surfactant may be
used that enhances the coating of the hydrophobic coating agent
onto the surface of the particulates. The surfactants may aid in
the dispersibility of the hydrophobic coating agent so as to
increase the portion of particulates thereby coated and so as to
enhance the ability of the hydrophobic coating agent to adhere to
the surface of the particulates.
[0028] The selection of an appropriate surfactant to enhance the
coating of the particulate surfaces may depend on, among other
factors, the type of particulates used, the composition of fluids
resident in the subterranean formation, and the conditions of the
subterranean formation, such as formation temperature. In certain
embodiments, for example, suitable surfactants may comprise
long-chain alkyl sulfates wherein the alkyl chain comprises from
about 6 carbon atoms to about 21 carbon atoms. An example of one
suitable long-chain alkyl sulfate is lauryl sulfate. Other suitable
surfactants may comprise one or more degradable surfactants,
wherein the surfactant molecules are derived from degradable
polymers and contain a backbone with repeating units of degradable
groups, such as esters or other derivatives, for example, such as
polycarbonates, polyacetals, poly(orthoesters), or polyesteramides
as the degradable hydrophobic block or tail in the surfactant
molecule attached to the hydrophilic polymeric block or head group.
Other suitable surfactants may include reactive surfactants, such
as non-migratory surfactants or "surfmers," which comprise
surfactants that carry one or more polymerizable functional groups.
Examples of reactive surfactants suitable for use in the present
invention are described in U.S. Patent Application Publication
Number 2005/0070679, filed Aug. 30, 2004, the relevant disclosure
of which is hereby incorporated by reference. The surfactant may be
present in a treatment fluid utilized in the present invention in
any amount that does not adversely affect the properties of the
particulates. In certain embodiments, the surfactant may be present
in an amount in the range of from about 0.01% to about 10% by
volume of a treatment fluid comprising the particulates being
treated. In certain embodiments, the surfactant may be present in
an amount in the range of from about 0.1% to about 2% by volume of
a treatment fluid comprising the particulates being treated.
II. Carrier Fluids Suitable for Use in the Present Invention
[0029] A carrier fluid may be used to introduce the particulates
into the subterranean formation, including fracturing carrier
fluids. Any carrier fluid that achieves the desired viscosity
effect for carrying and depositing the particulates in the
subterranean formation is suitable for use in the present
invention. Carrier fluids include any of the fracturing fluids
commonly known in the art such as, for example, fracturing fluids
comprising a liquid and a gelling agent.
III. Methods Generally and Coating Techniques
[0030] One embodiment of the present invention provides a method of
enhancing the recovery of an aqueous fluid from a subterranean
formation comprising: providing a plurality of particulates;
coating the plurality of particulates with a hydrophobic coating
agent so as to form a plurality of hydrophobically-coated
particulates; providing a carrier fluid; mixing the plurality of
hydrophobically-coated particulates with the carrier fluid so as to
form a pumpable slurry; introducing the plurality of
hydrophobically-coated particulates into the subterranean
formation; placing the plurality of hydrophobically-coated
particulates in the subterranean formation; and allowing a
treatment fluid to flow back through the plurality of
hydrophobically-coated particulates to recover a treatment fluid
that was previously-introduced into the subterranean formation.
[0031] Another embodiment of the present invention provides a
method of recovering a previously-introduced aqueous treatment
fluid from a subterranean formation comprising: providing a
plurality of particulates; introducing the plurality of
particulates into a subterranean well bore; introducing a
hydrophobic coating agent into the subterranean well bore; allowing
the hydrophobic coating agent to coat the plurality of particulates
so as to form a plurality of hydrophobically-coated particulates;
allowing the plurality of hydrophobically-coated particulates to be
placed in a portion of the subterranean formation; and allowing the
previously-introduced aqueous treatment fluid to flow back through
the plurality of hydrophobically-coated particulates.
[0032] Another embodiment of the present invention provides method
of enhancing the recovery of an aqueous treatment fluid from a
subterranean formation comprising: providing a plurality of
hydrophobically-coated particulates; placing the plurality of
hydrophobically-coated particulates in the subterranean formation;
and allowing a treatment fluid to flow back through the plurality
of hydrophobically-coated particulates to recover a treatment fluid
that was previously-introduced into the subterranean formation.
[0033] In practicing certain embodiments of the present invention,
the coating process of the plurality of particulates may be by any
method known in the art. This coating may be accomplished in
treatments performed prior to transporting the particulates to a
job site, or in a treatment performed "on-the-fly." The term
"on-the-fly" is used herein to mean that one flowing stream
comprising particulates is continuously introduced into another
flowing stream comprising the hydrophobic coating agent so that the
streams are combined and mixed while continuing to flow as a single
stream as part of the on-going treatment at the job site. Such
mixing can also be described as "real-time" mixing. One such
on-the-fly mixing method would involve continuously conveying the
particulates and the hydrophobic coating agent to a mixing vessel,
for example, using a sand screw. Once inside the mixing vessel, the
particulates would be contacted with the hydrophobic coating agent
and continuously removed from the mixing vessel. In that situation,
the sand screw could be used both to aid in mixing the
particulates, be they gravel, proppant, or some other particulates,
with the hydrophobic coating agent and to remove the hydrophobic
coating agent from the mixing tank. As is well understood by those
skilled in the art, batch or partial batch mixing may also be used
to accomplish such coating at a well site just prior to introducing
the particulates into a subterranean formation.
[0034] In certain exemplary embodiments, the hydrophobic coating
may remain on the particulates until the load recovery of the
aqueous treatment fluid has been completed. The hydrophobic coating
may remain on the particulates until after the completion of the
load recovery to provide continued enhanced recovery, but in
certain preferred embodiments, the coating will remain on the
particulates at least until the completion of the load recovery
process.
IV. Exemplary Resins and Tackifying Agents
[0035] In addition to the hydrophobic coating agents enumerated
above, suitable hydrophobic coating agents may include any suitable
resin composition or tackifying agent that results in a hydrophobic
coating on the surface area of the treated particulates as
discussed in this section.
[0036] A. Suitable Resins
[0037] Resins suitable for use in the consolidation fluids of the
present invention include all resins known in the art that are
capable of forming a hardened, consolidated mass.
[0038] In some embodiments, the hydrophobic coating agent may
comprise a resin. Resins suitable for use in the present invention
include all resins known and used in the art. Certain resins
suitable for use in the present invention may be capable of
increasing the water contact angle of a surface by at least about
20 degrees.
[0039] One resin-type coating material suitable for use in the
methods of the present invention is a two-component epoxy based
resin comprising a hardenable resin component and a hardening agent
component. The hardenable resin component is comprised of a
hardenable resin and an optional solvent. The solvent may be added
to the resin to reduce its viscosity for ease of handling, mixing
and transferring. Factors that may affect the decision to include a
solvent include geographic location of the well and the surrounding
weather conditions. An alternate way to reduce the viscosity of the
liquid hardenable resin is to heat it. This method avoids the use
of a solvent altogether, which may be desirable in certain
circumstances. The second component is the liquid hardening agent
component, which is comprised of a hardening agent, a silane
coupling agent, a surfactant, an optional hydrolyzable ester for,
among other things, breaking gelled fracturing fluid films on the
proppant particles, and an optional liquid carrier fluid for, among
other things, reducing the viscosity of the liquid hardening agent
component.
[0040] Examples of hardenable resins that can be used in the
hardenable resin component include, but are not limited to, organic
resins such as bisphenol A-diglycidyl ether resins, butoxymethyl
butyl glycidyl ether resins, bisphenol A-epichlorohydrin resins,
polyepoxide resins, novolak resins, polyester resins,
phenol-aldehyde resins, urea-aldehyde resins, furan resins,
urethane resins, glycidyl ether resins, and combinations thereof.
The hardenable resin used may be included in the hardenable resin
component in an amount in the range of from about 60% to about 100%
by weight of the hardenable resin component. In some embodiments,
the hardenable resin used may be included in the hardenable resin
component in an amount of about 70% to about 90% by weight of the
hardenable resin component.
[0041] Any solvent that is compatible with the hardenable resin and
achieves the desired viscosity effect is suitable for use in the
hardenable resin component in certain embodiments of 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 having at least one C.sub.1 to
C.sub.6 alkyl group, mono ethers of dihydric alkanols,
methoxypropanol, butoxyethanol, hexoxyethanol, and isomers thereof.
Aqueous solvents also may be used in the methods of the present
invention. In certain embodiments wherein an aqueous solvent is
used, certain additives may be used, among other purposes, to aid
in dispersing the resin in the aqueous solution. Selection of an
appropriate solvent is dependent on, inter alia, the resin
composition chosen.
[0042] As described above, use of a solvent in the hardenable resin
component is optional but may be desirable to reduce the viscosity
of the hardenable resin component for ease of handling, mixing, and
transferring. In some embodiments, the amount of the solvent used
in the hardenable resin component is in the range of from about
0.1% to about 30% by weight of the hardenable resin component.
Optionally, the hardenable resin component may be heated to reduce
its viscosity, in place of, or in addition to, using a solvent.
[0043] Examples of the hardening agents that can be used in the
liquid hardening agent component in certain embodiments of the
present invention include, but are not limited to, piperazine,
derivatives of piperazine (e.g., aminoethylpiperazine), 2H-pyrrole,
pyrrole, imidazole, pyrazole, pyridine, pyrazine, pyrimidine,
pyridazine, indolizine, isoindole, 3H-indole, indole, 1H-indazole,
purine, 4H-quinolizine, quinoline, isoquinoline, phthalazine,
naphthyridine, quinoxaline, quinazoline, 4H-carbazole, carbazole,
.beta.-carboline, phenanthridine, acridine, phenathroline,
phenazine, imidazolidine, phenoxazine, cinnoline, pyrrolidine,
pyrroline, imidazoline, piperidine, indoline, isoindoline,
quinuclindine, morpholine, azocine, azepine, 2H-azepine,
1,3,5-triazine, thiazole, pteridine, dihydroquinoline, hexa
methylene imine, indazole, amines, aromatic amines, polyamines,
aliphatic amines, cyclo-aliphatic amines, amides, polyamides,
2-ethyl-4-methyl imidazole, 1,1,3-trichlorotrifluoroacetone, and
combinations thereof. The chosen hardening agent often effects the
range of temperatures over which a hardenable resin is able to
cure. By way of example and not of limitation, in subterranean
formations having a temperature from about 60.degree. F. to about
250.degree. F., amines and cyclo-aliphatic amines such as
piperidine, triethylamine, N,N-dimethylaminopyridine,
benzyldimethylamine, tris(dimethylaminomethyl)phenol, and
2-(N.sub.2N-dimethylaminomethyl)phenol may be used. In subterranean
formations having higher temperatures, 4,4'-diaminodiphenyl sulfone
may be a suitable hardening agent. Hardening agents that comprise
piperazine or a derivative of piperazine have been shown capable of
curing various hardenable resins from temperatures as low as about
70.degree. F. to as high as about 350.degree. F. The hardening
agent used may be included in the liquid hardening agent component
in an amount sufficient to consolidate the coated particulates. In
some embodiments of the present invention, the hardening agent used
may be included in the liquid hardenable resin component in the
range of from about 40% to about 60% by weight of the liquid
hardening agent component. In some embodiments, the hardenable
resin used may be included in the hardenable resin component in an
amount of about 45% to about 55% by weight of the liquid hardening
agent component.
[0044] The silane coupling agent may be used, among other things,
to act as a mediator to help bond the resin to formation
particulates and/or proppant. Examples of suitable silane coupling
agents include, but are not limited to,
N-.beta.-(aminoethyl)-.gamma.-aminopropyl trimethoxysilane,
N-2-(aminoethyl)-3-aminopropyltrimethoxysilane,
3-glycidoxypropyltrimethoxysilane, and combinations thereof. The
silane coupling agent used may be included in the liquid hardening
agent component in an amount capable of sufficiently bonding the
resin to the mineral surface. In some embodiments of the present
invention, the silane coupling agent used may be included in the
liquid hardenable resin component in the range of from about 0.1%
to about 3% by weight of the liquid hardening agent component.
[0045] Any surfactant compatible with the hardening agent and
capable of facilitating the contacting of the resin onto mineral
surfaces of the particulates may be used in the hardening agent
component in certain embodiments of the present invention. Such
surfactants include, but are not limited to, an alkyl phosphonate
surfactant (e.g., a C.sub.12-C.sub.22 alkyl phosphonate
surfactant), an ethoxylated nonyl phenol phosphate ester, one or
more cationic surfactants, and one or more nonionic surfactants.
Mixtures of one or more cationic and nonionic surfactants also may
be suitable. Examples of such surfactant mixtures are described in
U.S. Pat. No. 6,311,773 issued to Todd et al. on Nov. 6, 2001, the
relevant disclosure of which is incorporated herein by reference.
The surfactant or surfactants used may be included in the liquid
hardening agent component in an amount in the range of from about
1% to about 10% by weight of the liquid hardening agent
component.
[0046] While not required, examples of hydrolysable esters that can
be used in the hardening agent component in certain embodiments of
the present invention include, but are not limited to, a mixture of
dimethylglutarate, dimethyladipate, dimethylsuccinate, sorbitol,
catechol, dimethylthiolate, methyl salicylate, dimethyl salicylate,
dimethylsuccinate, ter-butylhydroperoxide, and combinations
thereof. When used, a hydrolyzable ester may be included in the
hardening agent component in an amount in the range of from about
0.1% to about 3% by weight of the hardening agent component. In
some embodiments a hydrolysable ester is included in the hardening
agent component in an amount in the range of from about 1% to about
2.5% by weight of the hardening agent component.
[0047] Use of a diluent or liquid carrier fluid in the hardenable
resin composition is optional and may be used to reduce the
viscosity of the hardenable resin component for ease of handling,
mixing and transferring. Any suitable carrier fluid that is
compatible with the hardenable resin and achieves the desired
viscosity effects is suitable for use in the present invention.
Some suitable liquid carrier fluids are those having high flash
points (e.g., about 125.degree. F.) because of, among other things,
environmental and safety concerns; such solvents include, but are
not limited to, 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 suitable liquid carrier fluids include
aqueous dissolvable solvents such as, for example, methanol,
isopropanol, butanol, glycol ether solvents, and combinations
thereof. Suitable glycol ether liquid carrier fluids 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 having 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 liquid carrier fluid is dependent on, inter alia, the
resin composition chosen.
[0048] Another resin suitable for use in the methods of the present
invention are furan-based resins. Suitable furan-based resins
include, but are not limited to, furfuryl alcohol resins,
aldehydes, and a mixture of furan resins and phenolic resins. A
furan-based resin may be combined with a solvent to control
viscosity if desired. Suitable solvents for use with furan-based
resins include, but are not limited to, 2-butoxy ethanol, butyl
lactate, butyl acetate, tetrahydrofurfuryl methacrylate,
tetrahydrofurfuryl acrylate, esters of oxalic, maleic and succinic
acids, and furfuryl acetate.
[0049] Another resin suitable for use in the methods of the present
invention is a phenolic-based resin. Suitable phenolic-based resins
include, but are not limited to, terpolymers of phenol, phenolic
formaldehyde resins, and a mixture of phenolic and furan resins. A
phenolic-based resin may be combined with a solvent to control
viscosity if desired. Suitable solvents for use in the
phenolic-based consolidation fluids of the present invention
include, but are not limited to butyl acetate, butyl lactate,
furfuryl acetate, and 2-butoxy ethanol.
[0050] Another resin suitable for use in the methods of the present
invention is an HT epoxy-based resin. Suitable HT epoxy-based
components include, but are not limited to, bisphenol
A-epichlorohydrin resins, polyepoxide resins, novolac resins,
polyester resins, glycidyl ethers and mixtures thereof. An HT
epoxy-based resin may be combined with a solvent to control
viscosity if desired. Suitable solvents for use with the HT
epoxy-based resins of the present invention are those solvents
capable of substantially dissolving the HT epoxy-resin chosen for
use in the consolidation fluid. Such solvents include, but are not
limited to, dimethyl sulfoxide and dimethyl formamide. A co-solvent
such as a dipropylene glycol methyl ether, dipropylene glycol
dimethyl ether, dimethyl formamide, diethylene glycol methyl ether,
ethylene glycol butyl ether, diethylene glycol butyl ether,
propylene carbonate, d'limonene and fatty acid methyl esters, may
also be used in combination with the solvent.
[0051] Another resin-type coating material suitable for use in the
methods of the present invention is a phenol/phenol
formaldehyde/furfuryl alcohol resin comprising from about 5% to
about 30% phenol, from about 40% to about 70% phenol formaldehyde,
from about 10% to about 40% furfuryl alcohol, from about 0.1% to
about 3% of a silane coupling agent, and from about 1% to about 15%
of a surfactant. In the phenol/phenol formaldehyde/furfuryl alcohol
resins suitable for use in the methods of the present invention,
suitable silane coupling agents include, but are not limited to,
N-2-(aminoethyl)-3-aminopropyltrimethoxysilane,
3-glycidoxypropyltrimethoxysilane, and
n-.beta.-(aminoethyl)-.gamma.-aminopropyl trimethoxysilane.
Suitable surfactants include, but are not limited to, an
ethoxylated nonyl phenol phosphate ester, mixtures of one or more
cationic surfactants, and one or more non-ionic surfactants and an
alkyl phosphonate surfactant.
[0052] In certain embodiments, the resin may be present in an
amount in the range of from about 0.003 pounds to about 0.5 pounds
per square foot of surface area of mineral surface treated on the
particulates. In certain embodiments, the resin may be present in
an amount in the range of from about 0.03 pounds to about 0.12
pounds per square foot of surface area of the treated
particulates.
[0053] B. Suitable Tackifying Agents
[0054] Tackifying agents suitable for use in the methods of the
present invention exhibit a sticky character and, thus, impart a
degree of consolidation to unconsolidated or weakly consolidated
particulates in the subterranean formation. As used herein, a
"tackifying agent" refers to a composition having a nature such
that it is (or may be activated to become) somewhat sticky to the
touch. Examples of suitable tackifying agents suitable for use in
the present invention include non-aqueous tackifying agents;
aqueous tackifying agents; and silyl-modified polyamides.
[0055] Tackifying agents suitable for use in the present invention
include non-aqueous tackifying agents, aqueous tackifying agents,
and silyl-modified polyamides. Certain such tackifying agents
suitable for use in the present invention may be capable of
increasing the water contact angle of a surface by at least about
20 degrees. One group of non-aqueous tackifying agents suitable for
use in the present invention comprises polyamides that are liquids
or in solution at the temperature of the particulates such that
they are, by themselves, non-hardening when placed in contact with
the particulates. An example of one such tackifying agent is a
condensation reaction product comprised of commercially available
polyacids and a polyamine. Such commercial products include
compounds such as mixtures of C.sub.36 dibasic acids containing
some trimer and higher oligomers and also small amounts of monomer
acids that are reacted with polyamines. Other polyacids include
trimer acids, synthetic acids produced from fatty acids, maleic
anhydride, acrylic acid, and the like. Such acid compounds are
commercially available from companies such as Witco Corporation,
Union Camp, Chemtall, and Emery Industries. The reaction products
are available from, for example, Champion Technologies, Inc. and
Witco Corporation. In certain embodiments, a non-aqueous tackifying
agent may comprise an isopropyl alcohol solution of about 3%
polyamides by volume of the solution. Additional compounds which
may be used as non-aqueous tackifying compounds include liquids and
solutions of, for example, polyesters, polycarbonates,
polycarbamates, natural resins such as shellac, and the like. Other
suitable non-aqueous tackifying agents are described in U.S. Pat.
No. 5,853,048 issued to Weaver et al., U.S. Pat. No. 5,833,000
issued to Weaver et al., U.S. Pat. No. 5,582,249 issued to Weaver
et al., U.S. Pat. No. 5,775,425 issued to Weaver et al., and U.S.
Pat. No. 5,787,986 issued to Weaver et al., the relevant
disclosures of which are herein incorporated by reference. In
certain embodiments, the non-aqueous tackifying agent may be
present in an amount in the range of from about 0.003 pounds to
about 0.5 pounds per square foot of surface area of mineral surface
treated on the particulates. In certain embodiments, the
non-aqueous tackifying agent may be present in an amount in the
range of from about 0.03 pounds to about 0.12 pounds per square
foot of surface area of mineral surface treated on the
particulates.
[0056] Non-aqueous tackifying agents suitable for use in the
present invention may be either used such that they form a
non-hardening coating, or they may be combined with a
multifunctional material capable of reacting with the non-aqueous
tackifying agent to form a hardened coating. A "hardened coating,"
as used herein, means that the reaction of the tackifying compound
with the multifunctional material will result in a substantially
non-flowable reaction product that exhibits a higher compressive
strength in a consolidated agglomerate than the tackifying compound
alone with the particulates. In this instance, the non-aqueous
tackifying agent may function similarly to a hardenable resin.
Multifunctional materials suitable for use in the present invention
include, but are not limited to, aldehydes such as formaldehyde,
dialdehydes such as glutaraldehyde, hemiacetals or aldehyde
releasing compounds, diacid halides, dihalides such as dichlorides
and dibromides, polyacid anhydrides such as citric acid, epoxides,
furfuraldehyde, glutaraldehyde or aldehyde condensates and the
like, and combinations thereof. In some embodiments of the present
invention, the multifunctional material may be mixed with the
tackifying compound in an amount of from about 0.01% to about 50%
by weight of the tackifying compound to effect formation of the
reaction product. In some preferable embodiments, the compound is
present in an amount of from about 0.5% to about 1% by weight of
the tackifying compound. Suitable multifunctional materials are
described in U.S. Pat. No. 5,839,510 issued to Weaver et al., the
relevant disclosure of which is herein incorporated by
reference.
[0057] Solvents suitable for use with the non-aqueous tackifying
agents of the present invention include any solvent that is
compatible with the non-aqueous tackifying agent and achieves the
desired viscosity effect. The solvents that can be used in the
present invention preferably include those having high flash points
(most preferably above about 125.degree. F.). Examples of solvents
suitable for use in the present invention include, but are not
limited to, butylglycidyl ether, dipropylene glycol methyl ether,
butyl bottom alcohol, dipropylene glycol dimethyl ether,
diethyleneglycol methyl ether, ethyleneglycol butyl ether,
methanol, butyl alcohol, isopropyl alcohol, diethyleneglycol butyl
ether, propylene carbonate, d'limonene, 2-butoxy ethanol, butyl
acetate, furfuryl acetate, butyl lactate, dimethyl sulfoxide,
dimethyl formamide, fatty acid methyl esters, and combinations
thereof.
[0058] Aqueous tackifying agents suitable for use in the present
invention are not significantly tacky when placed onto a mineral
surface, but are capable of being "activated" (that is
destabilized, coalesced and/or reacted) to transform the compound
into a sticky, tackifying compound at a desirable time. In some
embodiments, a pretreatment may be first contacted with the mineral
surface to prepare it to be coated with an aqueous tackifying
agent. Suitable aqueous tackifying agents are generally charged
polymers that comprise compounds that, when in an aqueous solvent
or solution, will form a non-hardening coating (by itself or with
an activator) and, when placed on a particulate, will increase the
continuous critical resuspension velocity of the particulate when
contacted by a stream of water. The aqueous tackifying agent may,
inter alia, enhance the grain-to-grain contact between individual
particulates (be they proppant particulates, formation fines, or
other particulates) and/or to help bring about the consolidation of
the particulates into a cohesive, flexible, and permeable mass. In
certain embodiments, the aqueous tackifying agent may be present in
an amount in the range of from about 0.003 pounds to about 0.5
pounds per square foot of surface area of mineral surface treated
on the particulates. In certain embodiments, the aqueous tackifying
agent may be present in an amount in the range of from about 0.03
pounds to about 0.12 pounds per square foot of surface area of
mineral surface treated on the particulates.
[0059] Examples of aqueous tackifying agents 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), poly(butyl methacrylate), and
poly(2-ethylhexyl methacryate)), acrylamido-methyl-propane
sulfonate polymers, acrylamido-methyl-propane sulfonate derivative
polymers, acrylamido-methyl-propane sulfonate co-polymers, and
acrylic acid/acrylamido-methyl-propane sulfonate co-polymers, and
combinations thereof. Methods of determining suitable aqueous
tackifying agents and additional disclosure on aqueous tackifying
agents may be found in U.S. patent application Ser. No. 10/864,061,
filed Jun. 9, 2004, and U.S. patent application Ser. No.
10/864,618, filed Jun. 9, 2004, the relevant disclosures of which
are hereby incorporated by reference.
[0060] Silyl-modified polyamide compounds suitable for use as a
surface-treating reagent in the methods of the present invention
may be described as substantially self-hardening compositions that
are capable of at least partially adhering to surfaces in the
unhardened state, and that are further capable of self-hardening
themselves to a substantially non-tacky state to which individual
particulates will not adhere to, for example, in formation or
proppant pack pore throats. Such silyl-modified polyamides may be
based, for example, on the reaction product of a silating compound
with a polyamide or a mixture of polyamides. The polyamide or
mixture of polyamides may be one or more polyamide intermediate
compounds obtained, for example, from the reaction of a polyacid
(e.g., diacid or higher) with a polyamine (e.g., diamine or higher)
to form a polyamide polymer with the elimination of water. Other
suitable silyl-modified polyamides and methods of making such
compounds are described in U.S. Pat. No. 6,439,309 issued to
Matherly et al., the relevant disclosure of which is herein
incorporated by reference. In certain embodiments, the
silyl-modified polyamide compound may be present in an amount in
the range of from about 0.003 pounds to about 0.5 pounds per square
foot of surface area of mineral surface treated on the
particulates. In certain embodiments, the silyl-modified polyamide
compound may be present in an amount in the range of from about
0.03 pounds to about 0.12 pounds per square foot of surface area of
the treated particulates.
[0061] 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 scope of the invention
EXAMPLES
[0062] 30/70 mesh Brady sand was coated with a low molecular weight
polyamide solution and placed in a column pack. Water was used as a
simulated production fluid to compare the permeability of coated
proppant packs versus uncoated proppant packs. Laboratory results
from the column flow tests show that the hydrophobic coated
proppant packs have higher permeability to water as compared to the
uncoated packs as shown in FIG. 1. Table 1 shows the permeability
data that is depicted in FIG. 1. The data shows that increasing the
amount of hydrophobic coating on the particulates results in a
higher permeability of the column and thus demonstrates that
hydrophobic coated particulates may enhance the recovery of aqueous
treatment fluids. TABLE-US-00001 TABLE 1 COLUMN PERMEABILITY OF
PROPPANT PACKS VERSUS AMOUNT OF HYDROPHOBIC COATING Column
Permeability (Darcies) Pore 0% Hydrophobic 0.5% Hydrophobic 1.0%
Hydrophobic Volume Coating Agent Coating Agent Coating Agent 5.4
120.6 127.5 188.6 7.2 120.6 128.1 191.1 9.1 120.9 128.7 193.2 10.8
120.5 129.4 194.8 12.7 121.1 130.0 196.2 14.5 121.3 130.6 197.5
16.3 122.1 131.2 198.6 18.1 121.6 131.8 199.5 36.3 121.6 137.2
206.1 54.4 121.8 141.6 210.1 72.5 122.0 145.1 213.0 90.7 120.4
147.7 215.2 108.9 122.1 149.4 217.1 126.9 122.1 150.1 218.6 145.0
122.2 149.9 220.0 163.2 122.8 148.9 221.2 181.3 122.9 149.9
222.3
[0063] Therefore, the present invention is well adapted to attain
the ends and advantages mentioned as well as those that are
inherent therein. 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. The terms in
the claims have their plain, ordinary meaning unless otherwise
explicitly and clearly defined by the patentee.
* * * * *