U.S. patent application number 14/801619 was filed with the patent office on 2016-01-21 for aqueous slurry for particulates transportation.
The applicant listed for this patent is TRICAN WELL SERVICE LTD.. Invention is credited to Julius Xaver HEIDLAS, Weibing LU, Chuanzhong WANG, Kewei ZHANG.
Application Number | 20160017213 14/801619 |
Document ID | / |
Family ID | 55074037 |
Filed Date | 2016-01-21 |
United States Patent
Application |
20160017213 |
Kind Code |
A1 |
ZHANG; Kewei ; et
al. |
January 21, 2016 |
AQUEOUS SLURRY FOR PARTICULATES TRANSPORTATION
Abstract
An aqueous slurry composition for use in industries such as
petroleum and pipeline industries comprises an aqueous liquid,
particulates, a hydrophobizing agent that renders the particulate
surface hydrophobic and a hydrophobic polymer. The slurry is
produced by rendering the surface of the particulate hydrophobic
during or prior to making the slurry. The method and composition
can find many applications in different industries, particularly in
petroleum industry.
Inventors: |
ZHANG; Kewei; (Calgary,
CA) ; HEIDLAS; Julius Xaver; (Humble, TX) ;
WANG; Chuanzhong; (Calgary, CA) ; LU; Weibing;
(Calgary, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
TRICAN WELL SERVICE LTD. |
Calgary |
|
CA |
|
|
Family ID: |
55074037 |
Appl. No.: |
14/801619 |
Filed: |
July 16, 2015 |
Current U.S.
Class: |
507/202 ;
507/219; 507/221; 507/224; 507/231 |
Current CPC
Class: |
C09K 8/805 20130101;
E21B 43/267 20130101; E21B 43/168 20130101; E21B 43/26 20130101;
C09K 8/80 20130101; C09K 8/92 20130101; C09K 8/68 20130101; E21B
43/164 20130101; C09K 8/88 20130101 |
International
Class: |
C09K 8/80 20060101
C09K008/80; C09K 8/92 20060101 C09K008/92; E21B 43/267 20060101
E21B043/267 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 16, 2014 |
CA |
2856942 |
Claims
1. A well service slurry composition comprising: a) an aqueous
liquid; b) particulates; c) one or more hydrophobizing agents; and
d) one or more hydrophobic polymers.
2. The slurry composition of claim 1 wherein the one or more
hydrophobic polymers is a polyolefin, a styrene polymer, a vinyl
polymer, an acrylic polymer, a polyester, or a fluorinated or
silyl-modified derivative of a polyolefin, a styrene polymer, a
vinyl polymer, an acrylic polymer or a polyester.
3. The slurry composition of claim 1, wherein the one or more
hydrophobizing agents is an amine hydrophobizing agent.
4. The slurry composition of claim 1, wherein the one or more
hydrophobizing agents is a silicon or fluorinated hydrophobizing
agent.
5. The slurry composition of claim 1, wherein the slurry
composition further comprises a frother.
6. The slurry composition of claim 1, wherein the slurry
composition further comprises a gas.
7. The slurry composition of claim 1, wherein the slurry
composition further comprises an oil.
8. The slurry composition of claim 1, wherein the slurry
composition is a fracturing fluid and wherein the particulates are
proppants.
9. The slurry composition of claim 1, wherein the particulates are
sand proppants.
10. The slurry composition of claim 8, wherein the aqueous liquid
is flowback water from a previous fracturing operation.
11. A method of preparing an aqueous slurry composition comprising
the step of mixing an aqueous liquid, particulates, a hydrophobic
polymer and a hydrophobizing agent together to form a mixture.
12. The method of claim 11 further comprising the step of mixing
the particulates and the hydrophobizing agent together before
adding the hydrophobic polymer to the mixture.
13. The method of claim 11, wherein the hydrophobic polymer is a
polyolefin, a styrene polymer, a vinyl polymer, an acrylic polymer,
a polyester, or a fluorinated or silyl-modified derivative of a
polyolefin, a styrene polymer, a vinyl polymer, an acrylic polymer
or a polyester.
14. The method of claim 11, wherein the hydrophobizing agent is an
amine hydrophobizing agent.
15. The method of claim 11, wherein the hydrophobizing agent is a
silicon or fluorinated hydrophobizing agent.
16. The method of claim 11 further comprising the step of adding a
frother to the mixture.
17. The method of claim 11 further comprising the step of adding an
oil to the mixture.
18. The method of claim 11 further comprising the step of adding
gas to the mixture.
19. The method of claim 11, wherein the aqueous slurry composition
is a fracturing fluid and wherein the particulates are
proppants.
20. The method of claim 19, wherein the fracturing fluid is formed
simultaneously while it is being pumped into a formation.
21. The method of claim 19, wherein the aqueous liquid is flowback
water from a previous fracturing operation.
22. A method of preparing a well service slurry composition
comprising the steps of: a) contacting particulates with a liquid
medium containing a hydrophobizing agent and a hydrophobic polymer,
to form treated particulates; b) separating the treated
particulates from the liquid medium; and c) mixing the treated
particulates with an aqueous liquid to form the aqueous slurry
composition.
23. The method of claim 22, wherein the liquid medium is an aqueous
or a non-aqueous medium.
24. The method of claim 22, wherein the hydrophobic polymer is a
polyolefin, a styrene polymer, a vinyl polymer, an acrylic polymer,
a polyester, or a fluorinated or silyl-modified derivative of a
polyolefin, a styrene polymer, a vinyl polymer, an acrylic polymer
or a polyester.
25. The method of claim 22 wherein the hydrophobizing agent is an
amine hydrophobizing agent.
26. The method of claim 22, wherein the hydrophobizing agent is a
silicon or fluorinated hydrophobizing agent.
27. The method of claim 22, further comprising the step of adding a
frother and/or a gas and/or an oil to the aqueous slurry
composition.
28. The method of claim 22, wherein the aqueous slurry composition
is a fracturing fluid and wherein the particulates are
proppants.
29. The method of claim 28, wherein the aqueous liquid is flowback
water from a previous fracturing operation.
30. A method of preparing the well service slurry composition of
claim 1 comprising the steps of: a) contacting particulates with a
liquid medium containing a hydrophobizing agent to form treated
particulates; b) separating the treated particulates from the
liquid medium; and c) mixing the treated particulates with a
hydrophobic polymer and an aqueous liquid to form the aqueous
slurry composition.
31. The method of claim 30, wherein the liquid medium is an aqueous
or a non-aqueous medium.
32. The method of claim 30, wherein the hydrophobic polymer is a
polyolefin, a styrene polymer, a vinyl polymer, an acrylic polymer,
a polyester, or a fluorinated or silyl-modified derivative of a
polyolefin, a styrene polymer, a vinyl polymer, an acrylic polymer
or a polyester.
33. The method of claim 30 wherein the hydrophobizing agent is an
amine hydrophobizing agent.
34. The method of claim 30, wherein the hydrophobizing agent is a
silicon or fluorinated hydrophobizing agent.
35. The method of claim 30, further comprising the step of adding a
frother, and/or a gas and/or an oil to the aqueous slurry
composition.
36. The method of claim 30, wherein the aqueous slurry composition
is a fracturing fluid and wherein the particulates are
proppants.
37. The method of claim 36, wherein the aqueous liquid is flowback
water from a previous fracturing operation.
Description
FIELD
[0001] This disclosure relates to an aqueous slurry composition for
transporting particulates and to a method of making such a
composition.
BACKGROUND
[0002] Aqueous slurries, which basically comprise an aqueous medium
and particulates, are commonly used in the oil and gas industry to
transport particulates through a pipe or tube, either on ground, or
from the surface to a subterranean formation or from a subterranean
formation to the surface. The most commonly used particulates
include sand, ceramic particulates, glass spheres, bauxite
(aluminum oxide) particulates, resin coated particulates and
synthetic particulates. The particulates usually range in size from
about 10 to about 100 U.S. mesh, i.e., about 150 to 2000 .mu.m in
diameter and normally have significantly higher density than water.
For example, the density of sand is typically about 2.6 g/cm.sup.3
while the density of water is 1 g/cm.sup.3. Aqueous slurries are
widely used in petroleum industry, which include hydraulic
fracturing and drilling operations. To make a relatively stable
slurry, the particulates must be suspended in a liquid medium for a
lengthy period of time at static and/or dynamic conditions, and
therefore the viscosity or viscoelasticity of the fluid must be
sufficiently high in order to be able to suspend particulates. The
most commonly used method for increasing viscosity or
viscoelasticity of an aqueous liquid is by adding a viscosifier
(for example, a natural or synthetic polymer) or a viscoelastic
surfactant to the liquid.
[0003] Hydraulic fracturing is a technology commonly used in the
petroleum industry to enhance oil and gas production from a
subterranean formation. During the operation, a fracturing fluid is
injected through a wellbore into a subterranean formation at a
pressure sufficient to initiate fractures in the formation.
Frequently, the fracturing fluid comprises particulates, commonly
known as proppants, suspended in the fluid and transported as a
slurry into the fractures. For example, following the initiation of
the fractures the slurry transports the particulates into the
fractures. At the last stage of the fracturing operation,
fracturing fluid is flowed back to the surface leaving proppants in
the fractures forming proppant packs to prevent fractures from
closing after pressure is released (i.e., the particulates "prop"
open the fractures). The proppant packs provide highly conductive
channels that allow the hydrocarbons (e.g., oil and/or gas) to seep
through the formation to the wellbore more efficiently. Proppants,
including sands, ceramic particulates, bauxite particulates, glass
spheres, resin coated sands, synthetic particulates and the like,
are known in the industry. Among them sands are by far the most
commonly used proppants. As noted above, the proppants normally
range in size from about 10 to 100 U.S. mesh, which is about 150 to
2000 .mu.m in diameter.
[0004] Fracturing fluids in common use include various
aqueous-based and non-aqueous based (i.e., hydrocarbon-based)
fluids. Due to their low cost and high versatility, aqueous-based
fluids are preferred and most commonly used. To better transport
particulates, water-soluble viscosifiers, such as polymers (i.e.,
linear or cross-linked polymers) or viscoelastic surfactants are
added to increase fluid viscosity. For example, a polymer, such as
guar gum or its derivatives, is added into an aqueous liquid
wherein the physical entanglement of polymer chains increases the
fluid viscosity and thus its suspension capability. To further
enhance fluid viscosity, it is common to chemically cross-link
polymer chains by certain chemical compounds forming chemically
cross-linked gel. Guar gum cross-linked by borates is one example
of this. Compared to a cross-linked fluid, linear gels, i.e.,
fluids containing sufficient amount of polymers without
cross-linking, cause less formation damage and are more
cost-effective, but have relatively poor suspension capability. In
recent years, slick water, i.e., water containing very small amount
of friction reducing agent, which normally ranges from 0.015% to
0.1%, preferably 0.02% to 0.06%, of the fluid, has been widely used
as a fracturing fluid, especially for fracturing shale or tight
formations. Various water-soluble polymers, including guar gum and
its derivatives as well as polyacrylamide and its derivatives, have
been used as friction reducing agents. Polyacrylamide copolymers,
which contain other monomers in addition to acrylamide monomers,
are commonly used as friction reducing agents in hydraulic
fracturing operations. One such type of copolymer is a
hydrophobically modified polyacrylamide copolymer.
[0005] Viscoelastic fluids are the fluids that exhibit both viscous
and elastic characteristics when being subjected to stress and are
widely used to make aqueous slurries to transport particulates.
Basically, the viscosity of the fluid works to slow down the rate
of particulate settling out of suspension, while the elasticity
helps to suspend the particulates. Under dynamic conditions,
agitation or turbulence further help stabilize the slurry.
Therefore, conventional methods of making stable particulate
slurries focus on manipulating the rheological properties of the
fluid by adding sufficient amounts of a viscosifier, such as a
water-soluble polymer, to the slurry. It is not unusual that a
polymer is used together with a foaming agent to improve the
rheology and reduce the cost.
[0006] As noted above, the last stage of a fracturing treatment
involves the flowing of the fracturing fluid back to the surface
while the proppants are left in the fractures. However, it is not
unusual for a significant amount of proppant to be carried out of
the fractures and into the wellbore along with the fluids being
flowed back out of the well. This process is known as "proppant
flowback". Proppant flowback after fracturing treatments has long
plagued the petroleum industry. It is highly undesirable because it
not only reduces the amount of proppants remaining in the fractures
(thus, leading to reduced fracture conductivity), but also causes
significant operational difficulties. U.S. Pat. No. 6,047,772
indicates that different methods have been tried to address the
problem of proppant flowback. In one method, resins are used to
coat the proppant grains to make them tacky so that they stick
together to reduce proppant flowback. This method is expensive, and
operationally challenging.
[0007] There still exists a need for compositions and methods of
making slurries that will form a stable proppant pack in the
fracture formations and resist flowing back to the surface, while
at the same time being cost-effective and operationally simple.
[0008] When drilling subterranean formations for oil and gas,
aqueous-based drilling fluids are normally used. During the
drilling process large amounts of particulates, called cuttings,
are generated. Cuttings have different sizes ranging from fines to
pebbles. The drilling fluid is circulated through the wellbore to
make a slurry with the cuttings in situ and subsequently transport
them out of wellbore. In most cases, polymers as well as clays are
added to the drilling fluids to increase their
viscosity/viscoelasticity in order to transport the cuttings
efficiently. However, polymers and clay fines can easily penetrate
into pores or thin fractures in the formation and significantly
reduce formation permeability, especially at near wellbore. Reduced
formation permeability impedes oil and/or gas production. Therefore
it is highly desirable to have a drilling fluid that can make
stable slurry in situ with the cuttings and transport them out of
the wellbore, while at the same time cause less formation damage
(i.e., a fluid that does not impede the permeability of the
formation).
[0009] In oil sand operation massive amount of sands are left after
oil is stripped from the sand surface. Finding a more cost
efficient way to transport sands efficiently over distance through
pipelines has long been required in the industry.
[0010] U.S. Pat. Nos. 7,723,274 and 8,105,986 disclose a different
way of enhancing particulate transportation using a slurry. Unlike
the conventional way, which focuses on improving fluid rheology (as
discussed above), these patents teach that by rendering the
particulate surfaces sufficiently hydrophobic, gas bubbles become
attached to the particulate surfaces, thus buoying the
particulates, and consequently resulting in the formation of stable
slurry without requiring viscosifying of the fluid. Moreover, the
spontaneous attachment of bubbles to different particulates bridges
the particulates together resulting in particulate agglomeration
(aggregation). This is also known as gas bridging in the scientific
literature. The slurry can be used to effectively transport
particulates in different applications, particularly in hydraulic
fracturing operation.
SUMMARY
[0011] It has been found that the addition of a hydrophobic polymer
to a slurry composition, for example that disclosed in U.S. Pat.
Nos. 7,723,274 and 8,105,986, can significantly enhance the
attachment of bubbles to the particulate surfaces and can enhance
particulate agglomeration. Consequently the transportation
capability of the slurry is improved.
[0012] According to one aspect there is provided an aqueous slurry
composition comprising an aqueous liquid, particulates, a
hydrophobizing agent which renders the particulate surfaces
hydrophobic and a hydrophobic polymer. Also provided is a method of
making such an aqueous slurry composition. In some embodiments the
aqueous slurry composition is a fracturing fluid. In some
embodiments the particulates are proppants.
[0013] According to another aspect there is provided an aqueous
slurry composition comprising an aqueous liquid, particulates, a
hydrophobizing agent which renders the particulate surfaces
hydrophobic, a hydrophobic polymer and a gas. Also provided is a
method of making such an aqueous slurry composition. In some
embodiments the aqueous slurry composition is a fracturing fluid.
In some embodiments the particulates are proppants.
[0014] According to a further aspect there is provided an aqueous
slurry composition comprising an aqueous liquid, particulates, a
hydrophobizing agent which renders the particulate surfaces
hydrophobic, a hydrophobic polymer and a frother. Also provided is
a method of making such an aqueous slurry composition. In some
embodiments the aqueous slurry composition is a fracturing fluid.
In some embodiments the particulates are proppants.
[0015] According to a further aspect there is provided an aqueous
slurry composition comprising an aqueous liquid, particulates, a
hydrophobizing agent which renders the particulate surfaces
hydrophobic, a hydrophobic polymer and an oil. Also provided is a
method of making such an aqueous slurry composition. In some
embodiments the aqueous slurry composition is a fracturing fluid.
In some embodiments the particulates are proppants.
[0016] According to a further aspect there is provided a method of
treating proppants in a hydraulic fracturing operation by
contacting the proppants with a hydrophobizing agent which renders
the particulate surfaces hydrophobic and a hydrophobic polymer,
before or during the hydraulic fracturing operation.
[0017] According to a further aspect there is provided a method of
treating proppants in a hydraulic fracturing operation by
contacting the proppants with a hydrophobizing agent which renders
the particulate surfaces hydrophobic, a hydrophobic polymer and a
frother, before or during the hydraulic fracturing operation.
[0018] According to a further aspect, there is provided a method of
treating proppants in a hydraulic fracturing operation by
contacting the proppants with a hydrophobizing agent which renders
the particulate surfaces hydrophobic, a hydrophobic polymer and an
oil before or during such hydraulic fracturing operation. As well,
when used in fracturing operations, especially slick water
fracturing, water can be re-used after flowback from a previous
fracturing operation, to make the slurry.
[0019] In one aspect, described herein is a well service slurry
composition, including a fracturing fluid composition,
comprising:
a) an aqueous liquid; b) particulates; c) one or more
hydrophobizing agents; and d) one or more hydrophobic polymers.
[0020] The one or more hydrophobic polymers may be a polyolefin, a
styrene polymer, a vinyl polymer, an acrylic polymer, a polyester,
or a fluorinated or silyl-modified derivative of a polyolefin, a
styrene polymer, a vinyl polymer, an acrylic polymer or a
polyester.
[0021] The one or more hydrophobizing agents may be an amine
hydrophobizing agent, or a silicon or fluorinated hydrophobizing
agent. In various embodiments the slurry composition may further
comprise a frother, a gas, an oil, or a combination of these
agents.
[0022] In one embodiment the slurry composition is a fracturing
fluid and wherein the particulates are proppants. In one embodiment
the particulates are sand proppants. In one embodiment the aqueous
liquid is flowback water from a previous fracturing operation.
[0023] In another aspect, disclosed herein is a method of preparing
an aqueous slurry composition, including a fracturing fluid
composition, comprising the step of mixing an aqueous liquid,
particulates, a hydrophobic polymer and a hydrophobizing agent
together to form a mixture.
[0024] In one embodiment the method further comprises the step of
mixing the particulates and the hydrophobizing agent together
before adding the hydrophobic polymer to the mixture.
[0025] In one embodiment the hydrophobic polymer is a polyolefin, a
styrene polymer, a vinyl polymer, an acrylic polymer, a polyester,
or a fluorinated or silyl-modified derivative of a polyolefin, a
styrene polymer, a vinyl polymer, an acrylic polymer or a
polyester.
[0026] In one embodiment the hydrophobizing agent is an amine
hydrophobizing agent. In one embodiment the hydrophobizing agent is
a silicon or fluorinated hydrophobizing agent.
[0027] In one embodiment the method further comprises the step of
adding a frother, an oil, a gas, or combination of same, to the
mixture.
[0028] In one embodiment of the method the aqueous slurry
composition is a fracturing fluid and wherein the particulates are
proppants.
[0029] In one embodiment of the method, the fracturing fluid is
formed simultaneously while it is being pumped into a formation. In
one embodiment, the aqueous liquid is flowback water from a
previous fracturing operation.
[0030] In another aspect, described herein is a method of preparing
a well service slurry composition, including a fracturing fluid
composition, comprising the steps of:
a) contacting particulates with a liquid medium containing a
hydrophobizing agent and a hydrophobic polymer, to form treated
particulates; b) separating the treated particulates from the
liquid medium; and c) mixing the treated particulates with an
aqueous liquid to form the aqueous slurry composition.
[0031] The liquid medium may be an aqueous or a non-aqueous
medium.
[0032] The hydrophobic polymer may be a polyolefin, a styrene
polymer, a vinyl polymer, an acrylic polymer, a polyester, or a
fluorinated or silyl-modified derivative of a polyolefin, a styrene
polymer, a vinyl polymer, an acrylic polymer or a polyester.
[0033] The hydrophobizing agent may be an amine hydrophobizing
agent or a silicon or fluorinated hydrophobizing agent. The method
may further comprise the step of adding a frother and/or a gas
and/or an oil to the aqueous slurry composition.
[0034] In one embodiment of the method the aqueous slurry
composition is a fracturing fluid and the particulates are
proppants. In one embodiment of the method the aqueous liquid is
flowback water from a previous fracturing operation.
[0035] In another aspect, described herein is method of preparing a
well service slurry composition, including a fracturing fluid
composition, comprising the steps of:
a) contacting particulates with a liquid medium containing a
hydrophobizing agent to form treated particulates; b) separating
the treated particulates from the liquid medium; and c) mixing the
treated particulates with a hydrophobic polymer and an aqueous
liquid to form the aqueous slurry composition.
[0036] The liquid medium may be an aqueous or a non-aqueous
medium.
[0037] The hydrophobic polymer may be a polyolefin, a styrene
polymer, a vinyl polymer, an acrylic polymer, a polyester, or a
fluorinated or silyl-modified derivative of a polyolefin, a styrene
polymer, a vinyl polymer, an acrylic polymer or a polyester.
[0038] The hydrophobizing agent may be an amine hydrophobizing
agent or a silicon or fluorinated hydrophobizing agent. The method
may further comprise the step of adding a frother and/or a gas
and/or an oil to the aqueous slurry composition.
[0039] In one embodiment of the method the aqueous slurry
composition is a fracturing fluid and the particulates are
proppants. In one embodiment of the method the aqueous liquid is
flowback water from a previous fracturing operation.
DETAILED DESCRIPTION
[0040] For purposes of this specification and the claims appended
thereto, the term "hydrophobic polymer" is used herein to mean any
polymer that is non-wetting to water and typically has a water
contact angle approximately equal to or greater than 90.degree..
Examples of hydrophobic polymers, by way of illustration only,
include: (a) polyolefins, which is a class of polymers or
copolymers synthesized from a simple olefin as a monomer including,
polyethylene, poly(isobutene), poly(isoprene),
poly(4-methyl-1-pentene), polypropylene, ethylene propylene
copolymers, ethylene-propylene-hexadiene copolymers, and
ethylene-vinyl acetate copolymers; (b) styrene polymers, including
poly(styrene), poly(2-methylstyrene), styrene-acrylonitrile
copolymers having less than about 20 mole-percent acrylonitrile;
(c) vinyl polymers, such as poly(vinyl butyrate), poly(vinyl
decanoate), poly(vinyl dodecanoate), poly(vinyl hexadecanoate),
poly(vinyl hexanoate), poly(vinyl propionate), poly(vinyl
octanoate), and poly(methacrylonitnile); (d) acrylic polymers,
including poly(n-butyl acetate), poly(ethyl acrylate); methacrylic
polymers, such as poly(benzyl methacrylate), poly(n-butyl
methacrylate), poly(isobutyl methacrylate), poly(t-butyl
methacrylate), poly(t-butylaminoethyl methacrylate), poly(dodecyl
methacrylate), poly(ethyl methacrylate), poly(2-ethylhexyl
methacrylate), poly(n-hexyl methacrylate), poly(phenyl
methacrylate), poly(n-propyl methacrylate), poly(octadecyl
methacrylate); (e) polyesters, such as poly(ethylene
terephthalate), poly(butylene terephthalate), and poly(ethylene
terenaphthalate); and (f) fluorinated or silyl-modified derivatives
of above mentioned polymers, such as silyl-modified polyolefines,
silyl-modified polyacrylates, silyl-modified polyamides,
fluorinated olefin polymers, fluorinated vinyl polymers,
fluorinated styrene polymers, fluorinated acrylic polymers, and
fluorinated methacrylic polymers are included as well, including
poly(chlorotrifluoroethylene),
chlorotrifluoroethylenetetrafluoroethylene copolymers,
poly(hexafluoropropylene), poly(tetrafluoroethylene),
tetrafluoroethylene-ethylene copolymers, poly(trifluoroethylene),
and styrene-2,2,3,3,-tetrafluoropropyl methacrylate copolymers,
poly(vinyl fluoride), poly(vinylidene fluoride);
poly(heptafluoroisopropoxyethylene),
poly(heptafluoroisopropoxypropylene),
poly[(1-chlorodifluorornethyl)tetrafluoroethyl acrylate],
poly[di(chlorofluoromethyl) fluoromethyl acrylate],
poly(1,1-dihydroheptafluorobutylacrylate),
poly(1,1-dihydropentafluoroisopropyl acrylate),
poly(1.1-dihydropentadecafluorooctyl acrylate),
poly(heptafluoroisopropyl acrylate),
poly[5-(heptafluoroisopropoxy)pentyl acrylate],
poly[11-(heptafluoroisopropoxy) undecyl acrylate],
poly[2-(heptafluoropropoxy)ethyl acrylate], poly(nonafluoroisobutyl
acrylate); poly(1,1-dihydropentadecafluorooctyl methacrylate),
poly(heptafluoroisopropyl methacrylate), poly(heptadecafluorooctyl
methacrylate), poly(1-hydrotetrafluoroethyl methacrylate),
poly(1,1-dihydrotetrafluoropropyl methacrylate),
poly(1-hydrohexafluoroisopropyl methacrylate), and
poly(t-nonafluorobutyl methacrylate). Normally hydrophobic polymers
of low or moderate molecular weights are preferred. Furthermore,
hydrophobic polymers that are liquid or viscous liquid at moderate
conditions are also preferred.
[0041] The hydrophobizing agent used herein includes amine
hydrophobizing agents and silicon or fluorinated hydrophobizing
agents. The term "amine hydrophobizing agent" is used herein to
mean long carbon chain hydrocarbon amines (i.e., containing no
silicon or fluoro-based groups in the molecules). Such compounds
contain at least fourteen, preferably at least sixteen, carbon
atoms, which render the surface of the particulates hydrophobic.
These include simple primary, secondary and tertiary amines,
primary ether amines, di-amines, polyamines, ether diamines,
stearyl amines, tallow amines, condensates of amine or alkanolamine
with fatty acid or fatty acid ester, and condensates of
hydroxyethylendiamines. Examples include the condensate of
diethylenetetraamine and tallow oil fatty acid, tetradecyloxypropyl
amine, octadecyloxypropyl amine, hexadecyloxypropyl amine,
hexadecyl-1,3-propanediamine, tallow-1,3-propanediamine, hexadecyl
amine, tallow amine, soyaalkylamine, erucyl amine, hydrogenated
erucyl amine, ethoxylated erucyl amine, rapeseed amine,
hydrogenated rapeseed amine, ethoxylated rapeseed amine,
ethoxylated oleylamine, hydrogenated oleylamine, ethoxylated
hexadecyl amine, octadecylamine, ethoxylated octadecylamine,
ditallowamine, hydrogenated soyaalkylamine, amine, hydrogenated
tallow amine, di-octadecylamine, ethoxylated (2) tallowalkylamine,
for example Ethomeen.RTM. T/12 or ethoxylated (2) soyaalkylamine,
for example, Ethomeen.RTM. S/12, or oleyl amine, for example,
Armeen.RTM. OL, or di-cocoalkylalamine, for example Armeen.RTM. 2C
from Akzo Nobel Inc., and the condensate of an excess of fatty
acids with diethanolamine.
[0042] The term "silicon or fluorinated hydrophobizing agents" is
used herein to mean the hydrophobizing agents disclosed, for
example, in U.S. Pat. No. 7,723,274, which include different
organosilanes, organosiloxanes and polysiloxanes modified with
different functional groups, including cationic, amphoteric as well
as anionic groups, fluorinated silanes, fluorinated siloxanes and
fluorinated hydrocarbon compounds. In general, organosilanes are
compounds containing silicon to carbon bonds. Organosiloxanes are
compounds containing Si--O--Si bonds. Polysiloxanes are compounds
in which the elements silicon and oxygen alternate in the molecular
skeleton, i.e., Si--O--Si bonds are repeated. The simplest
polysiloxanes are polydimethylsiloxanes. Polysiloxane compounds can
be modified by various organic substitutes having different numbers
of carbons, which may contain N, S, or P moieties that impart
desired characteristics. For example, cationic polysiloxanes are
compounds in which one or more organic cationic groups are attached
to the polysiloxane chain, either at the middle or the end or both
at the same time. The most common organic cationic groups are
organic amine derivatives including primary, secondary, tertiary
and quaternary amines (for example, quaternary polysiloxanes
including, quaternary polysiloxanes including mono-as well as
di-quaternary polysiloxanes, amido quaternary polysiloxanes,
imidazoline quaternary polysiloxanes and carboxy quaternary
polysiloxanes). Similarly, the polysiloxane can be modified by
organic amphoteric groups, where one or more organic amphoteric
groups are attached to the polysiloxane chain, either at the middle
or the end or both, and include betaine polysiloxanes and
phosphobetaine polysiloxanes. Among different organosiloxane
compounds which are useful for the present compositions and methods
are polysiloxanes modified with organic amphoteric or cationic
groups including organic betaine polysiloxanes and organic amino or
quaternary polysiloxanes as examples. One type of betaine
polysiloxane or quaternary polysiloxane is represented by the
formula
##STR00001##
wherein each of the groups R.sub.1 to R.sub.6, and R.sub.8 to
R.sub.10 represents an alkyl containing 1-6 carbon atoms, typically
a methyl group, R.sub.7 represents an organic betaine group for
betaine polysiloxane, or an organic quaternary group for quaternary
polysiloxane, and have different numbers of carbon atoms, and may
contain a hydroxyl group or other functional groups containing N, P
or S, and m and n are from 1 to 200. For example, in one type of
quaternary polysiloxane R.sup.7 is represented by the group
##STR00002##
wherein R.sup.1, R.sup.2, R.sup.3 are alkyl groups with 1 to 22
carbon atoms or alkenyl groups with 2 to 22 carbon atoms. R.sup.4,
R.sup.5, R.sup.7 are alkyl groups with 1 to 22 carbon atoms or
alkenyl groups with 2 to 22 carbon atoms; R.sup.6 is --O-- or the
NR.sup.8 group, R.sup.8 being an alkyl or hydroxyalkyl group with 1
to 4 carbon atoms or a hydrogen group; Z is a bivalent hydrocarbon
group, which may have a hydroxyl group and may be interrupted by an
oxygen atom, an amino group or an amide group; x is 2 to 4; The
R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5, R.sup.7 may be the
same or different, and X.sup.- is an inorganic or organic anion
including Cl.sup.- and CH.sub.3COO.sup.-. Examples of organic
quaternary groups include
[R--N.sup.+(CH.sub.3).sub.2--CH.sub.2CH(OH)CH.sub.2--O--(CH.sub.2).sub.3--
-] (CH.sub.3COO.sup.-), wherein R is an alkyl group containing from
1-22 carbons or a benzyl radical and CH.sub.3COO.sup.- an anion.
Examples of organic betaine groups include
--(CH.sub.2).sub.3--O--CH.sub.2CH(OH)(CH.sub.2)--N.sup.+(CH.sub.3).sub.2C-
H.sub.2COO.sup.-. Such compounds are commercially available. It
should be understood that cationic polysiloxanes include compounds
represented by formula (II), wherein R.sub.7 represents other
organic amine derivatives including organic primary, secondary and
tertiary amines.
[0043] Other examples of organo-modified polysiloxanes include
di-betaine polysiloxanes and di-quaternary polysiloxanes, which can
be represented by the formula
##STR00003##
wherein the groups R.sub.12 to R.sub.17 each represent an alkyl
containing 1-6 carbon atoms, typically a methyl group, the R.sub.11
and R.sub.18 groups represent an organic betaine group for
di-betaine polysiloxanes or an organic quaternary group for
di-quaternary, and have different numbers of carbon atoms and may
contain a hydroxyl group or other functional groups containing N, P
or S, and m is from 1 to 200. For example, in one type of
di-quaternary polysiloxane R.sub.11 and R.sub.18 are represented by
the group
##STR00004##
wherein R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5, R.sup.6,
R.sup.7, Z, X.sup.- and x are the same as defined above. Such
compounds are commercially available. Quaternium 80 (INCI) is one
of the commercial examples.
[0044] Similarly, the polysiloxane can be modified by organic
anionic groups, where one or more organic anionic groups are
attached to the polysiloxane chain, either at the middle or the end
or both, including sulfate polysiloxanes, phosphate polysiloxanes,
carboxylate polysiloxanes, sulfonate polysiloxanes, thiosulfate
polysiloxanes. The organosiloxane compounds also include
alkylsiloxanes including hexamethylcyclotrisiloxane,
octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane,
hexamethyldisiloxane, hexaethyldisiloxane,
1,3-divinyl-1,1,3,3-tetramethyldisiloxane, octamethyltrisiloxane,
decamethyltetrasiloxane. The organosilane compounds include
alkylchlorosilane, for example methyltrichlorosilane,
dimethyldichlorosilane, trimethylchlorosilane,
octadecyltrichlorosilane; alkyl-alkoxysilane compounds, for example
methyl-, propyl-, isobutyl- and octyltrialkoxysilanes, and
fluoro-organosilane compounds, for example,
2-(n-perfluoro-octyl)-ethyltriethoxysilane, and
perfluoro-octyldimethyl chlorosilane. Other types of chemical
compounds, which are not organosilicon compounds, which can be used
to render proppant surfaces hydrophobic are certain
fluoro-substituted compounds, for example certain fluoro-organic
compounds including cationic fluoro-organic compounds. Further
information regarding organosilicon compounds can be found in U.S.
Pat. No. 7,723,274 and Silicone Surfactants (Randal M. Hill, 1999)
and the references therein, and in U.S. Pat. Nos. 4,046,795;
4,537,595; 4,564,456; 4,689,085; 4,960,845; 5,098,979; 5,149,765;
5,209,775; 5,240,760; 5,256,805; 5,359,104; 6,132,638 and 6,830,811
and Canadian Patent No. 2,213,168. Organosilanes can be represented
by the formula
R.sub.nSiX.sub.(4-n) (I)
wherein R is an organic radical having 1-50 carbon atoms that may
possess functionality containing N, S, or P moieties that impart
desired characteristics, X is a halogen, alkoxy, acyloxy or amine
and n has a value of 1-3. Examples of suitable organosilanes
include: Si(OCH.sub.3).sub.4, CH.sub.3Si(OCH.sub.3).sub.3,
CH.sub.3Si(OCH.sub.2CH.sub.3).sub.3,
CH.sub.3Si(OCH.sub.2CH.sub.2CH.sub.3).sub.3,
CH.sub.3Si[O(CH.sub.2).sub.3CH.sub.3].sub.3;
CH.sub.3CH.sub.2Si(OCH.sub.2CH.sub.3).sub.3,
C.sub.6H.sub.5Si(OCH.sub.3).sub.3,
C.sub.6H.sub.5CH.sub.2Si(OCH.sub.3).sub.3,
C.sub.6H.sub.5Si(OCH.sub.2CH.sub.3).sub.3,
CH.sub.2.dbd.CHCH.sub.2Si(OCH.sub.3).sub.3,
(CH.sub.3).sub.2Si(OCH.sub.3).sub.2,
(CH.sub.2.dbd.CH)Si(CH.sub.3).sub.2Cl,
(CH.sub.3).sub.2Si(OCH.sub.2CH.sub.3).sub.2,
(CH.sub.3).sub.2Si(OCH.sub.2CH.sub.2CH.sub.3).sub.2,
(CH.sub.3).sub.2Si[O(CH.sub.2).sub.3CH.sub.3].sub.2,
(CH.sub.3CH.sub.2).sub.2Si(OCH.sub.2CH.sub.3).sub.2,
(C.sub.6H.sub.5).sub.2Si(OCH.sub.3).sub.2,
(C.sub.6H.sub.5CH.sub.2).sub.2Si(OCH.sub.3).sub.2,
(C.sub.6H.sub.5).sub.2Si(OCH.sub.2CH.sub.3).sub.2,
(CH.sub.2.dbd.CH)Si(OCH.sub.3).sub.2,
(CH.sub.2.dbd.CHCH.sub.2).sub.2Si(OCH.sub.3).sub.2,
(CH.sub.3).sub.3SiOCH.sub.3, CH.sub.3HSi(OCH.sub.3).sub.2,
(CH.sub.3).sub.2HSi(OCH.sub.3),
CH.sub.3Si(OCH.sub.2CH.sub.2CH.sub.3).sub.3,
CH.sub.2.dbd.CHCH.sub.2Si(OCH.sub.2CH.sub.2OCH.sub.3).sub.3,
(C.sub.6H.sub.5).sub.2Si(OCH.sub.2CH.sub.2OCH.sub.3).sub.2,
(CH.sub.3).sub.2Si(OCH.sub.2CH.sub.2OCH.sub.3).sub.2,
(CH.sub.2.dbd.CH.sub.2).sub.2Si(OCH.sub.2CH.sub.2OCH.sub.3).sub.2,
(CH.sub.2.dbd.CHCH.sub.2).sub.2Si(OCH.sub.2CH.sub.2OCH.sub.3).sub.2,
(C.sub.6H.sub.5).sub.2Si(OCH.sub.2CH.sub.2OCH.sub.3).sub.2,
CH.sub.3Si(CH.sub.3COO).sub.3, 3-aminotriethoxysilane,
methyldiethylchlorosilane, butyltrichlorosilane,
diphenyldichlorosilane, vinyltrichlorosilane,
methyltrimethoxysilane, vinyltriethoxysilane,
vinyltris(methoxyethoxy) silane,
methacryloxypropyltrimethoxysilane,
glycidoxypropyltrimethoxysilane, aminopropyltriethoxysilane,
divinyldi-2-methoxysilane, ethyltributoxysilane,
isobutyltrimethoxysilane, hexyltrimethoxysilane,
n-octyltriethoxysilane, dihexyldimethoxysilane,
octadecyltrichlorosilane, octadecyltrimethoxysilane,
octadecyldimethylchlorosilane, octadecyldimethylmethoxysilane and
quaternary ammonium silanes including
3-(trimethoxysilyl)propyldimethyloctadecyl ammonium chloride,
3-(trimethoxysilyl)propyldimethyloctadecyl ammonium bromide,
3-(trimethylethoxysilylpropyl)didecylmethyl ammonium chloride,
triethoxysilyl soyapropyl dimonium chloride,
3-(trimethylethoxysilylpropyl)didecylmethyl ammonium bromide,
3-(trimethylethoxysilylpropyl)didecylmethyl ammonium bromide,
triethoxysilyl soyapropyl dimonium bromide,
(CH.sub.3O).sub.3Si(CH.sub.2).sub.3P.sup.+(C.sub.6H.sub.5).sub.3Cl,
(CH.sub.3O).sub.3Si(CH.sub.2).sub.3P.sup.+(C.sub.6H.sub.5).sub.3Br.sup.-,
(CH.sub.3O).sub.3Si(CH.sub.2).sub.3P.sup.+(CH.sub.3).sub.3Cl.sup.-,
(CH.sub.3O).sub.3Si(CH.sub.2).sub.3P.sup.+(C.sub.6H.sub.5).sub.3Cl.sup.-,
(CH.sub.3O).sub.3Si(CH.sub.2).sub.3N.sup.+(CH.sub.3).sub.2C.sub.4H.sub.9C-
l,
(CH.sub.3O).sub.3Si(CH.sub.2).sub.3N.sup.+(CH.sub.3).sub.2CH.sub.2C.sub-
.6H.sub.5Cl.sup.-,
(CH.sub.3O).sub.3Si(CH.sub.2).sub.3N.sup.+(CH.sub.3).sub.2CH.sub.2CH.sub.-
2OHCl.sup.-,
(CH.sub.3O).sub.3Si(CH.sub.2).sub.3N.sup.+(C.sub.2H.sub.5).sub.3Cl.sup.-,
(C.sub.2H.sub.5O).sub.3Si(CH.sub.2).sub.3N.sup.+(CH.sub.3).sub.2C.sub.18H-
.sub.37Cl.sup.-. It is well known that some silanes, for example,
alkoxy silanes, undergo hydrolysis in aqueous medium before
reacting with hydroxyl groups (--OH) on the particulate surfaces,
for example, sand surfaces.
[0045] The term "frother" is used herein to mean a compound that
acts to stabilize bubbles so that they will remain well-dispersed
in the slurry. The most commonly used frothers are aliphatic
alcohols, including particularly, methyl isobutyl carbinol (MIBC),
2-ethyl hexanol, n-pentanol, n-butyl, n-hexanol, 2-butanol,
n-heptanol, n-octanol, isoamyl alcohol as well as cyclic alcohols
including pine oil, terpineol, fenchyl alcohol, alkoxy paraffins
such as 1,1,3,-triethoxybutane (TEB) and polypropyl glycol ethers
such as commercial products Dowfroths.RTM. by Dow Chemicals
Company. It is understood that mixtures of different frothers, such
as mixtures of the alcohols, are often used. As well, oils
including hydrocarbon oils such as mineral oils or paraffin oils
and natural oils can be used alone or in combination with, for
example, an alcohol frother, to stabilize the bubbles on the
particulate surfaces and enhance particulate agglomeration.
[0046] The term "aqueous liquid" or "aqueous fluid" is used herein
to mean water, salt solutions, or water containing an alcohol or
other organic solvents. It should be understood that additives
other than water in the aqueous liquid should be used in amounts or
in a manner that does not adversely affect the methods and
compositions described herein. The size of particulates in the
compositions and methods described herein is about 10-100 U.S.
mesh, which is about 150 to 2000 .mu.m in diameter. It should be
understood that the size distribution of the particulates, such as
proppants, can be narrow or wide. Suitable proppants include sands,
ceramic proppants, glass beads/spheres, bauxite proppants,
synthetic particulates and any other proppants known in the
industry.
[0047] The slurries described herein can be made on the surface or
in situ in a subterranean formation. Furthermore, a gas can be
mixed into the slurry. Suitable gases include air, carbon dioxide,
nitrogen, methane and mixtures thereof. The gas can be introduced
into the slurry during preparation thereof. For example, when the
slurry is pumped through a pipe, gas such as air or nitrogen can be
introduced into the slurry.
[0048] The slurry compositions described herein, particularly those
suitable for use in hydraulic fracturing operations, comprise an
aqueous liquid, proppants, such as sands, one or more
hydrophobizing agents as described herein (such as a stearyl amine,
tallow amine, a cationic modified polysiloxane, an amine silane or
an alkoxy silane), and one or more hydrophobic polymers (for
example, a polyolefin such as poly(isobutene) or poly(isoprene)).
The compositions may also include a frother such as MIBC or a small
amount of oil, or a frother/oil combination. Furthermore, a gas
such as air, nitrogen or carbon dioxide (or mixtures thereof) can
also be added to the slurry compositions.
[0049] For hydraulic fracturing operations, the slurries can be
prepared, for example on-the-fly, by mixing an aqueous liquid,
proppants, such as sands, one or more hydrophobizing agents as
described herein (such as a stearyl amine, tallow amine, a cationic
modified polysiloxane, an amine silane or an alkoxy silane), and
one or more hydrophobic polymers (for example, a polyolefin such as
poly(isobutene) or poly(isoprene)) using conventional mixing
methods under sufficient shear while pumping the slurry into the
subterranean formation. Additionally, the slurries may further
comprise a frother such as MIBC, or an oil, such as a mineral oil,
or a frother/oil combination. Such frothers, oils or frother/oil
combinations can be premixed with the hydrophobizing agent and
hydrophobic polymer or can be added separately in the slurry to
enhance the particulate floatation. Furthermore, a gas such as air,
nitrogen or carbon dioxide (or mixtures thereof) can also be added
to the slurry.
[0050] Alternatively, proppants can be pre-treated prior to being
introduced into the fluid, wherein proppants are first treated by
contacting the proppants with a liquid medium containing one or
more hydrophobizing agents as described herein (such as a stearyl
amine, a cationic modified polysiloxane, an amine silane or an
alkoxy silane), one or more hydrophobic polymers, for example, a
polyolefin (such as poly(isobutene) or poly(isoprene)), and then
separating the treated proppants from the medium. The liquid medium
used for pre-treating the proppants can be aqueous or non-aqueous.
The pre-hydrophobized proppants, i.e., treated proppants, can later
be mixed with an aqueous liquid containing a small amount of oil,
such as mineral oil, to make the slurry during a hydraulic
fracturing operation. Alternatively, the pre-treated proppants can
later be mixed with an aqueous liquid containing a frother, such as
MIBC, to make the slurry during a hydraulic fracturing operation.
Finally, the pre-treated proppants can later be mixed with an
aqueous liquid containing a frother/oil mixture. Furthermore, a gas
such as air, nitrogen or carbon dioxide (or mixtures thereof) can
also be added to the slurry.
[0051] In another embodiment, proppants can first be treated by
contacting the proppants with a liquid medium containing one or
more hydrophobizing agents as described herein, one or more
hydrophobic polymers, and oil, and then separating the proppants
from the medium. The pre-treated proppants can later be mixed with
an aqueous liquid to make the slurry during a hydraulic fracturing
operation. A frother can be added to the slurry composition while
pumping. Furthermore, a gas such as air, nitrogen or carbon dioxide
(or mixtures thereof) can also be added to the slurry.
[0052] In another embodiment, proppants can first be treated by
contacting the proppants with a medium containing one or more
hydrophobic polymers and then separating the proppants from the
medium. The pre-treated proppants can later be mixed with an
aqueous liquid containing one or more hydrophobizing agents as
described herein and a small amount of oil, such as mineral oil, to
make the slurry during a hydraulic fracturing operation.
Alternatively, the pre-treated proppants can later be mixed with an
aqueous liquid containing a frother, such as MIBC, to make the
slurry during a hydraulic fracturing operation. Finally, the
pre-treated proppants can later be mixed with an aqueous liquid
containing a frother/oil mixture. Furthermore, a gas such as air,
nitrogen or carbon dioxide (or mixtures thereof) can also be added
to the slurry.
[0053] In a further embodiment, proppants can first be treated by
contacting the proppants with a medium containing one or more
hydrophobic polymers and oil and then separating the proppants from
the medium. The pre-treated proppants can later be mixed with an
aqueous liquid comprising one or more hydrophobizing agents as
described herein to make the slurry during a hydraulic fracturing
operation. A frother can also be added to the slurry composition.
Furthermore, a gas such as air, nitrogen or carbon dioxide (or
mixtures thereof) can also be added to the slurry.
[0054] In another embodiment, proppants can first be treated by
contacting the proppants with a medium containing one or more
hydrophobizing agents as described herein and then separating the
proppants from the medium. The pre-treated proppants can later be
mixed with an aqueous liquid comprising one or more hydrophobic
polymers. This aqueous liquid may also comprise a small amount of
oil, such as mineral oil, or a frother, such as MIBC, or a
frother/oil mixture. Furthermore, a gas such as air, nitrogen or
carbon dioxide (or mixtures thereof) can also be added to the
slurry.
[0055] Normally, a frother such as MIBS or n-hexanol, or an oil,
are added in a small amount, which is less than 2% and preferably
less than 1% of the total fluid volume.
[0056] In another embodiment, proppants can be pre-treated
on-the-fly in a fracturing operation wherein the proppants are
pre-treated prior to being added to the blender while at the same
time fluid is pumped into a well. There are a few methods of
pre-treating on-the-fly. In one method, prior to being added into
the blender, proppants are first treated by contacting the
proppants (for example by spraying), with a liquid medium
containing one or more hydrophobizing agents as described herein
(such as tallow amine, a cationic modified polysiloxane, an amine
silane or an alkoxy silane), one or more hydrophobic polymers (such
as a polyolefin including poly(isobutene) and poly(isoprene)), and
either an oil, or a frother or a frother/oil mixture. The
pre-treated proppants are subsequently mixed with an aqueous liquid
while being pumped into a well.
[0057] In an alternative embodiment, proppant can be first treated
on-the-fly, for example by contacting the proppants (for example,
by spraying), prior to being added to the blender, with a medium
containing one or more hydrophobizing agents as described herein,
and the pre-treated proppants are subsequently mixed with an
aqueous liquid containing one or more hydrophobic polymers and
either an oil, or a frother or a frother/oil mixture while being
pumped into a well.
[0058] In another embodiment, the proppants can be pre-treated
on-the-fly by contacting the proppants with a medium (for example
by spraying), prior to adding into the blender, containing one or
more hydrophobic polymers (for example, a polyolefin such as
poly(isobutene)) and an oil (for example, mineral oil), and the
pre-treated proppants are subsequently mixed with an aqueous liquid
containing one or more hydrophobizing agents as described herein,
while being pumped into a well. A frother can be added to the
slurry composition while pumping.
[0059] In another embodiment, proppants are pre-treated by
contacting the proppants (for example by spraying), prior to being
added into the blender, with a medium containing one or more
hydrophobizing agents as described herein (for example, an
octadecylamine, a cationic modified polysiloxane, an amine silane
or an alkoxy silane), and one or more hydrophobic polymers (for
example, polyolefin including poly(isobutene) and poly(isoprene)),
and subsequently mixing with an aqueous liquid containing either an
oil, a frother or a frother/oil mixture while being pumped into a
well.
[0060] In an another embodiment, proppant can be first treated
on-the-fly, for example by contacting the proppants (for example,
by spraying), prior to being added to the blender, with a medium
containing one or more hydrophobic polymers and the pre-treated
proppants are subsequently mixed with an aqueous liquid containing
one or more hydrophobizing agents as described herein, and either
an oil, or a frother or a frother/oil mixture while being pumped
into a well.
[0061] Optionally, a gas such as air, nitrogen or carbon dioxide
(or mixtures thereof) can also be added to the slurry compositions.
Normally, a frother such as MIBS or n-hexanol, or an oil are added
in a small amount, which is less than 2% and preferably less than
1% of the total fluid volume.
[0062] With all of the above-mentioned applications the hydrophobic
polymers may, in some cases, be further chemically cross-linked
with each other or with the hydrophobizing agent, normally in the
presence of a catalyst, after they are attached to the surfaces of
the particulates.
[0063] Various proppants known to the industry, including sands and
ceramic proppants, can be treated according to the present
disclosure during the manufacturing process, where the proppants
are treated and then transported to the well site for the
fracturing operations. In each case, a gas, such as air, nitrogen
or carbon dioxide and mixtures thereof, can also be mixed into the
slurry under agitation. As noted above, the slurry can be prepared
on surface (above ground) or in a subterranean formation where
proppants, an aqueous fluid, and a hydrophobizing agent are mixed
in situ. With the composition described herein, a high
concentration of proppants can easily be pumped into a formation
and the proppants are more evenly distributed in the fracture,
leading to improved proppant conductivity.
[0064] In each case water, especially slick water, where the fluid
itself has very limited proppant transportation capability, is
particularly preferred as the fracturing fluid. Linear gels of guar
gum and its derivatives or polyacrylamide polymer or its copolymers
including hydrophobically modified polyacrylamide can be used as
well.
[0065] The amount of hydrophobizing agent, the hydrophobic polymer
and oil used in the methods and compositions described herein
depends to a large extent upon the type of particulates, the
concentration of the particulates, as well as the fluid used. In
general, more hydrophobizing agent and hydrophobic polymer and oil
are required when particulates concentration is high.
[0066] Another benefit of the slurries described herein is that
water in the slurry can be re-used, after it is separated from the
proppants after a fracturing operation. The flowback water from a
previous fracturing operation, especially fracturing operation
using slick water, or mixture of flowback water and fresh water can
be used in the compositions and methods described herein. This has
great significance considering there is limited water supply in the
world for hydraulic fracturing operations, especially in shale
formations.
[0067] This disclosure also provides a method for preventing
proppant flowback after a fracturing operation. Because of
agglomeration, proppants in the slurry described herein tend to
move cohesively, in contrast to conventional slurries under the
same conditions. It is found that addition of oil, such as
hydrocarbon oils, silicone oils, mineral oils, vegetable oils, or
combinations thereof, to the slurry can significantly strengthen
the proppant agglomeration. Proppant agglomeration makes it harder
for fluid being flowed back to the surface (flowback fluid) to
carry the proppants out of fractures, thus reducing proppant
flowback. The strength of proppant agglomeration appears to depend
on the contact angle formed between an oil drop and a proppant
surface in water as well as on the solid/water interfacial tension.
The strength of proppant agglomeration also appears to depend, to
some extent, on the amount of oil used for the agglomeration.
[0068] The methods and compositions described herein are
particularly useful in gravel-pack operations where sand slurry is
normally pumped into a wellbore to prevent excessive amount of
sands from flowing into the wellbore from the formation. The
present method is cost effective.
[0069] Similarly, the methods and compositions described herein can
also be used in so-called formation consolidation operations. In
such an operation, a fluid containing, for example, a
hydrophobizing agent as described herein, a hydrophobic polymer and
oil, is injected into a formation to increase cohesiveness among
sand grains to consolidate the formation and to reduce sand
production.
[0070] In drilling operations, for example, a hydrophobizing agent,
a hydrophobic polymer and an oil can be added into a water-based
drilling fluid. It is particularly useful when the composition is
added to water or brine for use as a drilling fluid. During a
drilling operation, the fluid forms a slurry in situ with cuttings
and transports the cuttings out of the wellbore. Furthermore, a gas
such as nitrogen or carbon dioxide can be mixed with the slurry
during drilling. Since it is not necessary to use polymers or clays
to viscosify the fluid, there is much less formation damage.
Moreover, the cuttings can be easily removed on the surface and the
aqueous liquid becomes re-useable. Different formations including
sandstone, carbonate, shale and coal seams can be drilled using the
slurry described herein.
[0071] Similarly in wellbore cleanout operations, for example,
water containing an amine hydrophobizing agent, a hydrophobic
polymer, a frother and occasionally an oil can be circulated
through the wellbore and form slurry with debris in situ. The
debris is subsequently transported out of the wellbore. The fluid
is re-useable after separation from the debris.
[0072] For transporting particulates through pipelines the slurry
can be prepared by mixing an aqueous liquid, particulates and a
hydrophobizing agent, a hydrophobic polymer, a frother and then
pumping the slurry through the pipeline. Alternatively, a gas such
as nitrogen can be included in the slurry as well.
[0073] The following are non-limiting examples of fluid
compositions and methods embodying the principles described
herein.
Examples
[0074] Sample A: comprises of 59.5% of poly(isobutylene), 40% MIBC
and 0.5% of stearylamine. The molecular weight of poly(isobutylene)
is about 1,000.
[0075] Sample B: comprises of 59.5% of poly(isobutylene), 40% MIBC
and 0.5% of tallow amine TA-100. The molecular weight of
poly(isobutylene) is about 1,000.
[0076] Sample C: comprises of 59.5% of poly(isobutylene), 40% MIBC
and 0.5% of ARMEEN.RTM. OL. The molecular weight of
poly(isobutylene) is about 1,000.
[0077] Sample D: comprises of 59.5% of poly(isobutylene), 40%
2-ethyl-1-hexanol and 0.5% of ETHOMEEN.RTM. S/12. The molecular
weight of poly(isobutylene) is about 1,000.
[0078] Sample E: comprises of 55.5% of poly(isoprene), 28% MIBC and
16% of limonene, and 0.5% of stearylamine.
[0079] Sample F: comprises of 10% of polystyrene, 0.5% of
stearylamine and 89.5% xylene.
[0080] Sample G: comprises of 10% of poly[di(ethylene glycol)
adipate], 0.5% of ARMEEN.RTM. OL and 40% 2-ethyl-1-hexanol. The
molecular weight of poly[di(ethylene glycol) adipate] is
.about.2,500.
[0081] Sample H: comprises of 10% of poly(isobutyl methacrylate),
0.5% of ARMEEN.RTM. OL and 89.5% xylene. The molecular weight of
poly(isobutyl methacrylate) is .about.70,000.
[0082] Sample I: comprises of 10% of polyethylene, 0.5% of
ARMEEN.RTM. OL and 89.5% xylene. The molecular weight of
polyethylene is .about.4,000.
[0083] Sample J: comprises of 59.5% of poly(isobutylene) and 40.5%
MIBC. The molecular weight of poly(isobutylene) is about 1,000.
[0084] Sample K: comprises of 59.5% of poly(isobutylene), 40% MIBC
and 0.5% of amine functionalized silicone polymer. The molecular
weight of poly(isobutylene) is about 1,500.
Example 1
[0085] 200 ml of water and 60 g of 20/40 mesh frac sand were added
into a lab blender. Under moderate shear rate (5000 rpm), 4 ml of
Sample A was added to the sand/water mixture in the blender. Then
0.2 ml of GFR-1, which is a polyacrylamide based friction reducing
agent (about 30% active), was added to the blender. The slurry was
sheared for about 15 seconds at 10,000 rpm. It was observed that
about 60% of sand was floating on the top.
Example 2
[0086] 0.3 ml of Sample A was mixed with 60 g of 20/40 frac sand.
Then the mixture was added into a lab blender which contained 200
ml of water. The slurry was sheared for 15 seconds at a moderate
rate, which is about 2500 rpm. It was observed that almost of sand
was floating on the top.
Example 3
[0087] 0.3 ml of Sample B was mixed with 60 g of 20/40 frac sand.
Then the mixture was added into a lab blender which contained 200
ml of water. The slurry was sheared for 15 seconds at a moderate
rate. It was observed that almost of sand was floating on the
top.
Example 4
[0088] 0.3 ml of Sample C was mixed with 60 g of 20/40 frac sand.
Then the mixture was added into a lab blender which contained 200
ml of 0.1% GFR-1 aqueous solution. The slurry was sheared for 15
seconds at a moderate rate. It was observed that 50% of sand was
floating on the top.
Example 5
[0089] 0.3 ml of Sample D was mixed with 60 g of 40/70 frac sand.
Then the mixture was added into a lab blender which contained 200
ml of water. The slurry was sheared for 15 seconds at a moderate
rate. It was observed that 70% of sand was floating on the top.
Example 6
[0090] 0.3 ml of Sample E was mixed with 60 g of 20/40 frac sand.
Then the mixture was added into a lab blender which contained 200
ml of water. The slurry was sheared for 15 seconds at a moderate
rate. It was observed that almost all of sand was floating on the
top.
Example 7
[0091] 0.3 ml of Sample F was mixed with 60 g of 20/40 frac sand.
Then the mixture was added into a lab blender which contained 200
ml of water. The slurry was sheared for 15 seconds at a moderate
rate. It was observed that around 50-60% of sand was floating on
the top.
Example 8
[0092] 0.3 ml of Sample G was mixed with 60 g of 20/40 frac sand.
Then the mixture was added into a lab blender which contained 200
ml of 0.1% GFR-1 aqueous solution. The slurry was sheared for 15
seconds at a moderate rate. It was observed that around 50-60% of
sand was floating on the top.
Comparative Example 8a
[0093] For comparison, Sample G' was prepared by replacing the
hydrophobic polymer, poly[di(ethylene glycol) adipate], in Sample G
with same amount of mineral oil while other components and
concentrations remained the same, i.e., Sample G' comprises of
59.5% of Envirodrill.RTM. mineral oil, 0.5% of ARMEEN.RTM. OL and
40% 2-ethyl-1-hexanol. 0.3 ml of Sample G' was mixed with 60 g of
20/40 frac sand. Then the mixture was added into a lab blender
which contained 200 ml of 0.1% GFR-1 aqueous solution. The slurry
was sheared for 15 seconds at a moderate rate. It was observed that
less than 10% of sand was floating on the top. This example
demonstrates that, as compared to mineral oil, poly[di(ethylene
glycol) adipate] is much more effective at promoting
agglomeration.
Example 9
[0094] 0.3 ml of Sample H was mixed with 60 g of 40/70 frac sand.
Then the mixture was added into a lab blender which contained 200
ml of 0.1% GFR-1 aqueous solution. The slurry was shear for 15
seconds at a moderate rate. It was observed that around 50-60% of
sand was floating on the top.
Example 10
[0095] 0.3 ml of Sample I was mixed with 60 g of 40/70 frac sand.
Then the mixture was added into a lab blender which contained 200
ml of 0.1% GFR-1 aqueous solution. The slurry was sheared for 15
seconds at a moderate rate. It was observed that around 40-50% of
sand was floating on the top.
Example 11
[0096] 0.3 ml of Sample J was mixed with 60 g of 20/40 frac sand.
Then the mixture was added into a lab blender which contained 200
ml of 0.1% GFR-1 aqueous solution. The slurry was sheared for 15
seconds at a moderate rate. It was observed that around 70% of sand
was floating on the top.
Example 11
[0097] 0.3 ml of Sample J was mixed with 60 g of 20/40 frac sand.
Then the mixture was added into a lab blender which contained 200
ml of 0.1% GFR-1 aqueous solution. The slurry was sheared for 15
seconds at a moderate rate. It was observed that around 70-80% of
sand was floating on the top.
Comparative Example 11a
[0098] For comparison, Sample J' was prepared by replacing the
hydrophobic polymer, poly(isobutylene), in Sample J with same
amount of mineral oil while other components and concentrations
remained the same, i.e., Sample J' comprises of 59% of
Envirodrill.RTM. mineral oil, 40% MIBC and 1% of amine
functionalized silicone polymer. 0.3 ml of Sample J' was mixed with
60 g of 20/40 frac sand. Then the mixture was added into a lab
blender which contained 200 ml of 0.1% GFR-1 aqueous solution. The
slurry was sheared for 15 seconds at a moderate rate. It was
observed that around 30% of sand was floating on the top. This
example demonstrates that, as compared to mineral oil,
poly(isobutylene) is much more effective at promoting
agglomeration.
Example 12
[0099] 0.3 ml of Sample K was mixed with 60 g of 40/70 frac sand.
Then the mixture was added into a lab blender which contained 200
ml of water. The slurry was sheared for 15 seconds at a moderate
rate. It was observed that almost all of sand was settling on the
bottom.
* * * * *