Note: Descriptions are shown in the official language in which they were submitted.
DEFOAMING COMPOSITIONS
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims priority to U.S. Provisional Application
61/541,790, filed September 30, 2011.
FIELD OF THE ART
[0002] The present disclosure generally relates to defoaming compositions and
methods for reducing air entrainment in fluids.
BACKGROUND
[0003] Worldwide, it is estimated that 1.8 billion tonnes of Portland cement
are
produced annually making it one of the most widely used manmade products on
earth.
Concrete and other cement-based materials define a major component of the
materials
used in civil engineering applications such as buildings, bridges, roads and
other
transportation infrastructures, as well as underground constructions such as
cementing a
well bore.
[0004] Primary cementing is the process of placing cement in the annulus
between
the casing and the formations exposed to the wellbore. Since its inception in
1903, the
major objective of primary cementing has always been to provide zonal
isolation in the oil,
gas and water wells. To achieve this objective, a hydraulic seal must be
created between
the casing and cement and between the cement and the formations, while at the
same time
preventing fluid channels in the cement sheath. Oil and gas cementing service
companies
have introduced various chemical additives in order to achieve and improve
desired
properties of cement slurries. Many of such cement additives can cause the
slurry to foam
during mixing. Excessive slurry foaming can have several undesirable
consequences.
Slurry gelation can result, and loss of hydraulic pressure during pumping can
occur owing
to cavitation on the mixing system. In addition, air entrainment may cause
undesired slurry
densities to be pumped down hole as measured density at surface will be
different than
actual downhole density increasing the risk of formation damage.
[0005] During slurry mixing, a densitometer or mass flow meter is used to help
field operators proportion the solid and liquid ingredients. If air is present
in the slurry at
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the surface, the density of the system "cement + water + air" is measured by
the
densitometer. Since the air becomes compressed downhole, the true downhole
slurry
density becomes higher than the measured surface density which can damage the
formation. Antifoaming or defoaming agents are usually added to the mix water
or dry-
blended with the cement to prevent such problems. They may also be used for
breaking
foamed fluids. In such applications, defoamer may be utilized to break the
excess foamed
fluid returned to surface after well treatment and thus facilitate disposal
process. In
general, desirable antifoaming or defoaming agents, have the following
characteristics to
be effective: a) insoluble in the foaming system, and b) lower surface tension
than the
foaming system. The antifoaming agent functions largely by spreading on the
surface of
the foam or entering the foam lamella. Because the film formed by the spread
of antifoam
on the surface of a foaming liquid does not support foam, the foam situation
is alleviated.
BRIEF SUMMARY
[0006] Disclosed herein are defoaming compositions comprising one or more
organic acid ester polymers selected from an organic acid ester of
polyethylene oxide
polymer, an organic acid ester of polypropylene oxide polymer, and a mixture
thereof. In
certain embodiments, the compositions may further comprise an organic acid
ester of an
ethylene oxide-propylene oxide block copolymer. Cement compositions including
the
defoaming composition, methods for reducing air entrainment in cement
compositions,
and methods for cementing a subterranean formation are also disclosed herein.
[0007] The disclosure may be understood more readily by reference to the
following detailed description of the various features of the disclosure and
the examples
included therein.
BRIEF DESCRIPTIONS OF THE DRAWINGS
[0008] Figure 1 is a graph of the defoaming effect of various dioleate esters
of
polyoxyethylene (EO) polymers on cement slurry density. Average molecular
weight of EO
DO -1, EO DO -2 and EO DO -3 esters are, 828, 928 and 1128 Daltons,
respectively.
Dosages are given as BWOC.
[0009] Figure 2 is a graph of the defoaming effect of various dioleate esters
of
polyoxypropylene (PO) polymers on cement slurry density. Average molecular
weight of
PO DO -1, PO DO -2 and PO DO -3 esters are, 1528, 2528 and 4528 Daltons,
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respectively. Dosages are given as BWOC.
[0010] Figure 3 is a graph of the defoaming effect of PO DO esters in
combination
with EO or EO/PO diesters. Defoaming compositions are described in Table 4.
[0011] Figure 4 is a graph of the defoaming effect of EO DO esters, EO/PO
diesters, and various mixtures thereof. Defoaming compositions are described
in Table 5.
DETAILED DESCRIPTION
[0012] Defoaming compositions and methods for reducing the air entrainment in
a
fluid such as a cement composition are provided. The defoaming compositions
generally
comprise one or more organic acid ester polymers selected from an organic acid
ester of
polyethylene oxide polymer, an organic acid ester of polypropylene oxide
polymer, and a
mixture thereof. In certain embodiments, the compositions may further comprise
an organic
acid ester of an ethylene oxide-propylene oxide block copolymer.
[0013] In other embodiments, one or more organic acid ester polymers selected
from (a) an organic acid ester of polyethylene oxide polymer, (b) an organic
acid ester of
polypropylene oxide polymer, and (c) an organic acid ester of an ethylene
oxide-propylene
oxide block copolymer.
[0014] In certain embodiments, the defoaming compositions comprise two or more
organic acid ester polymers selected from (a) an organic acid ester of
polyethylene oxide
polymer, (b) an organic acid ester of polypropylene oxide polymer, and (c) an
organic acid
ester of an ethylene oxide-propylene oxide block copolymer.
[0015] In any of the foregoing embodiments, the organic acid ester compounds
have a low acid number, for example less than 15.
[0016] These defoaming compositions provide effective foam control by reducing
air entrainment relative to other conventional defoamers, are relatively
biodegradable, and
are less toxic.
[0017] In one embodiment, the composition comprises an organic acid ester of
polyethylene oxide polymer. In another embodiment, the composition comprises
an
organic acid ester of polypropylene oxide polymer. In certain embodiments, the
composition comprises an organic acid ester of an ethylene oxide-propylene
oxide block
copolymer. In another embodiment, the composition comprises an organic acid
ester of an
ethylene oxide-propylene oxide block copolymer and an organic acid ester of
polyethylene
oxide polymer or an organic acid ester of polypropylene oxide polymer.
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[0018] In one embodiment, the composition comprises an organic acid ester of
polyethylene oxide polymer and an organic acid ester of polypropylene oxide
polymer. In
one embodiment, the composition comprises an organic acid ester of
polyethylene oxide
polymer and an organic acid ester of an ethylene oxide-propylene oxide block
copolymer.
In another embodiment, the composition comprises an organic acid ester of
polypropylene
oxide polymer, and an organic acid ester of an ethylene oxide-propylene oxide
block
copolymer.
[0019] In one embodiment, the composition comprises an organic acid ester of
polyethylene oxide polymer of the formula:
0 0
RO ______
0-./-/--R
n'
wherein R is a linear or branched, saturated or unsaturated, alkyl or alkyl
carboxylate
group having from 3 to 40 carbon atoms; and n' is 4 to 23.
[0020] In one embodiment, the composition comprises an organic acid ester of
polypropylene oxide polymer of the formula:
0 CH3 0
0 _______ OR
-n
wherein R is a linear or branched, saturated or unsaturated, alkyl or alkyl
carboxylate
group having from 3 to 40 carbon atoms; and n is 16 to 68.
[0021] In one embodiment, the composition comprises an organic acid ester of
an
ethylene oxide-propylene oxide block copolymer of the formula:
0 CH3 0
10' ____ C) 0
a[ a __ OR
wherein R is a linear or branched, saturated or unsaturated, alkyl or alkyl
carboxylate
group having from 3 to 40 carbon atoms, a is 2 to 8 and b is 16 to 68.
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[0022] In one embodiment, the defoaming composition comprises an organic acid
ester of polyethylene oxide polymer and an organic acid ester of polypropylene
oxide
polymer. In certain embodiments, the organic acid ester moieties of the
organic acid ester
of polyethylene oxide polymer and the organic acid ester of polypropylene
oxide polymer
are the same. In certain embodiments, the organic acid ester moieties of the
organic acid
ester of polyethylene oxide polymer and the organic acid ester of
polypropylene oxide
polymer are the different.
[0023] In one embodiment, the defoaming composition comprises an organic acid
ester of polyethylene oxide polymer and an organic acid ester of an ethylene
oxide-
propylene oxide block copolymer. In certain embodiments, the organic acid
ester moieties
of the organic acid ester of polyethylene oxide polymer and the organic acid
ester of an
ethylene oxide-propylene oxide block copolymer are the same. In certain
embodiments,
the organic acid ester moieties of the organic acid ester of polyethylene
oxide polymer and
the organic acid ester of an ethylene oxide-propylene oxide block copolymer
are the
different.
[0024] In one embodiment, the defoaming composition comprises an organic acid
ester of polypropylene oxide polymer and an organic acid ester of an ethylene
oxide-
propylene oxide block copolymer. In certain embodiments, the organic acid
ester moieties
of the organic acid ester of polypropylene oxide polymer and the organic acid
ester of an
ethylene oxide-propylene oxide block copolymer are the same. In certain
embodiments,
the organic acid ester moieties of the organic acid ester of polypropylene
oxide polymer
and the organic acid ester of an ethylene oxide-propylene oxide block
copolymer are the
different.
[0025] As used herein, the terms "polymer," "polymers," "polymeric," and
similar
terms are used in their ordinary sense as understood by one skilled in the
art, and thus may
be used herein to refer to or describe a large molecule (or group of such
molecules) that
contains recurring units. Polymers may be formed in various ways, including by
polymerizing monomers and/or by chemically modifying one or more recurring
units of a
precursor polymer. A polymer may be a "homopolymer" comprising substantially
identical recurring units form by, e.g., polymerizing a particular monomer. A
polymer may
also be a "copolymer" comprising two or more different recurring units formed
by, e.g.,
copolymerizing two or more different monomers, and/or by chemically modifying
one or
more recurring units of a precursor polymer.
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[0026] Polyoxyethylene, also known as polyethylene glycol (PEG), has low
toxicity and is used in variety of products. Suitable polyoxyethylene polymers
for use in
the present invention are terminated with hydroxyl groups and have a molecular
weight
from about 200 to about 1000 Daltons. In certain embodiments, the average
molecular
weight of the polymer is about 200 to about 600 Daltons. In other embodiments,
the
average molecular weight of the polymer is about 300 to about 400 Daltons.
[0027] Polyoxypropylene, also known as polypropylene glycol (PPG), is less
toxic
than PEG. Suitable polyoxypropylene polymers are terminated with hydroxyl
group,
having a molecular weight from 1000 to 4000 Daltons.
[0028] Organic acid esters of polyoxyethylene or polyoxypropylene are suitable
for use in the defoaming compositions described herein. The organic acid ester
of either
the polyoxyethylene polymer or the polyoxypropylene polymer is the reaction
product of
the polymer and an organic acid that has at least one carboxylic acid group,
including
mono-, di- or multi-carboxylic acid functionalities. Suitable organic acids
include,
without limitation, oleic acid, stearic acid, suberic acid, azelaic acid,
sebacic acid, phthalic
acid, isophthalic acid, terephthalic acid, and mixtures thereof. The organic
acid ester of the
polyoxypropylene polymer or the polyoxyethylene polymer are of the formulas
shown
below:
0 CH3 0
0 ___________________________________ 0 R
0 0
_____________________________________ OR
n'
[0029] wherein R is a linear or branched, saturated or unsaturated, alkyl or
alkyl
carboxylate group having from 3 to 40 carbon atoms, n is 16 to 68 and n' is 4
to 23. Many
PEG and PPG diesters are commercially available.
[0030] The block copolymer of ethylene oxide and propylene oxide is not
intended
to be limited to any particular structure and is commercially available in
several types.
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Suitable polyoxyethylene-polyoxypropylene copolymers are terminated with
hydroxyl
groups and generally have an average molecular weight of 1000 to 5000 Daltons,
and in
other embodiments, an average molecular weight of 2000 to 4000 Daltons, and in
still
other embodiments, an average molecular weight of 2000 to 2750 Daltons and
preferably
possess a melting point below 20 C. For example, Poloxamers are nonionic
triblock
copolymers composed of a central hydrophobic chain of polypropylene oxide
flanked by
two hydrophilic chains of polyethylene oxide. A schematic representation of a
Poloxamer
copolymer is shown here:
CH3
H _____________ C)* _________________ ,0" ______ OH
[0031] The ethylene oxide and propylene oxide block copolymers are also known
by trade names Pluronic from BASF and Mulsifan from Zschimmer & Schwarz GmbH
& Co. Because the lengths of the polymer blocks can be customized, many
different
EO/PO block copolymers exist having slightly different properties.
[0032] The organic acid ester of the ethylene oxide-propylene oxide block
copolymer is the reaction product of the block copolymer and an organic acid
that has at
least one carboxylic acid group, including mono-, di- or multi-carboxylic acid
functionalities. Suitable organic acids include, without limitation, oleic
acid, stearic acid,
suberic acid, azelaic acid, sebacic acid, phthalic acid, isophthalic acid,
terephthalic acid,
and mixtures thereof.
[0033] The organic acid ester of the ethylene oxide-propylene oxide is of the
general structure:
-
c)H [(3, ____________________________________ OR
a - a
[0034] wherein R is a linear or branched, saturated or unsaturated, alkyl or
alkyl
carboxylatc group or aryl or aryl carboxylate group having from 3 to 40 carbon
atoms, a is
2 to 8 and b is 16 to 68. As noted above, the composition has a low acid
value. In one
embodiment, the acid value is less than 15, and in other embodiments, the acid
value is
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less than 5. As used herein, the term acid value generally refers to the
number of
milligrams of potassium hydroxide needed to neutralize the carboxylic acid
groups in one
gram of polymer. Thus, in the case of di- and multi-carboxylic acid esters,
the free
carboxylic acid groups, if present, may be further esterified to prevent
adverse effects on
other fluid properties. The particular block structure is not intended to be
limited and may
have an ordered (E0-PO-E0 or PO-E0-P0) or random arrangements. For example, in
some embodiments, the polyoxyethylene-polyoxypropylene portion has a
polyoxypropylene backbone with polyoxyethylene end cap whereas in other
embodiments,
the polyoxyethylene-polyoxypropylene fatty acid esters have a polyoxyethylene
backbone
with polyoxypropylenc end caps. Still further, in some embodiments, the
backbone alkyl
group R may further include hydroxyl containing substituents such as may occur
using
castor oil derivatives as the di- or multicarboxylic acid.
[0035] The polyoxyethylene-polyoxypropylene organic acid esters can be
prepared
by conventional means such as by a condensation reaction of the desired
alcohol (e.g.,
polyethylene glycol-polypropylene glycol (E0/P0) block polymer) with a mono-,
di- or
multi-carboxylic acid in the presence of a suitable catalyst at an elevated
temperature.
Alternatively, the polyoxyethylene-polyoxypropylene organic acid esters can be
prepared
by transesterification of the EO/P0 block copolymer with a triglyceride of the
desired
mono-, di-, or multi-carboxylic acid and a base such a potassium hydroxide or
other
suitable alkalis as the catalyst.
[0036] In any of the foregoing embodiments, the organic acid ester may be an
oleic acid ester.
[0037] In a particular embodiment, the compositions may further comprise
hydrophobic solids. The optional hydrophobic solids such as silicon dioxide
(silica) may
be used to enhance the performance of the esters defoaming ability. The
hydrophobic
silica may fumed, precipitated, or a mixture thereof. Other suitable
hydrophobic solids
include talc, clays, aluminosilcates, mica, alumina and such.
[0038] The defoaming compositions may also be diluted in a diluent system, for
example an organic diluent or mixture of diluents. Such diluents include but
are not
limited to mineral oil, vegetable oil, alpha olefins, glycols, alcohols,
kerosene and
mixtures thereof. The defoaming compositions may also comprise water. In
particular
embodiments, the defoaming composition comprises vegetable oil.
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[0039] In one embodiment, the defoaming composition comprises one or more
organic acid ester polymers selected from (a) an organic acid ester of
polyethylene oxide
polymer, (b) an organic acid ester of polypropylene oxide polymer, and (c) an
organic acid
ester of an ethylene oxide-propylene oxide block copolymer; and each component
may
comprise from about 0 to about 100% by weight of the organic acid ester
polymers in the
composition. In certain embodiments, two or more types of organic acid esters
polymers
are included in the composition and each polymer may comprises from about 1%
to about
99%, about 2% to about 98%, about 5% to about 95%, about 10% to about 90%,
about
15% to about 85%, about 20% to about 80%, about 25% to about 75%, about 30% to
about 70%, about 35% to about 65%, about 40% to about 60%, about 45% to about
55%,
or about 50% each, by weight of the organic acid ester polymers in the
composition.
[0040] The defoaming composition including the organic acid esters of the
polyoxyethylene, polyoxypropylene and/or ethylene oxide-propylene oxide block
copolymer as described herein can be added to cement compositions at 0.01 to 1
% by
weight of the cement (BWOC).
[0041] The defoaming compositions can be added to the cement composition
before, during, or after blending of the various components of the cement
composition.
The defoaming compositions can be added as a liquid or as an emulsion or as
dry products
as may be desired for the intended application. In one exemplary embodiment,
the
defoaming composition can be combined with a cementitious material and a fluid
such as
water to form the cement composition before or during the blending of those
components.
This blending can occur at the pumphead, which displaces the cement
composition down
through the annulus of a wellbore (i.e., the area between a pipe in the
wellbore and the
wall of the wellbore) wherein it is allowed to set into a hard material, for
example cement.
The defoaming compositions serve to prevent or reduce the formation of foam
during the
preparation or pumping of the cement composition or to break the foam from a
well
treatment fluid returned to the surface. In another embodiment, the defoaming
composition
can be added to an already prepared cement composition before pumping the
composition
into a subterranean formation where it is allowed to set into a hard cement.
In this case, the
defoaming composition can serve to prevent or reduce the formation of foam in
the
cement composition as it is being pumped. In each of these embodiments, the
ability of the
defoaming composition to reduce the level of gas entrained in the cement
composition can
result in the formation of relatively stronger cement that can properly
support the piping in
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the wellbore. The defoaming composition can also be incorporated in the cement
composition to help control the density of the ensuing hardened cement. In yet
another
embodiment, the defoaming compositions can be combined with a previously
foamed
wellbore treatment fluid such as a foamed cement or foamed drilling mud to
break or
reduce the foam therein. Due to the removal of the foam, the wellbore
treatment fluid can
be readily disposed of after its use.
[0042] In one embodiment, a method for reducing air entrainment in a cement
composition is provided, the method comprising: adding a defoaming composition
to a
cement composition wherein the defoaming composition comprises one or more
organic
acid ester polymers selected from an organic acid ester of polyethylene oxide
polymer, an
organic acid ester of polypropylene oxide polymer, and mixtures thereof;
wherein the air
entrainment in the cement composition is reduced relative to a cement
composition
without the defoaming composition. In certain embodiments, the composition may
further
comprise an organic acid ester of an ethylene oxide-propylene oxide block
copolymer. In
certain embodiments, the defoaming composition is added to the cement
composition at 0.01
to 1% by weight of the cement.
[0043] In one embodiment, a method for reducing air entrainment in a cement
composition is provided, the method comprising: adding a defoaming composition
to a
cement composition wherein the defoaming composition comprises one or more
organic
acid ester polymers selected from (a) an organic acid ester of polyethylene
oxide polymer,
(b) an organic acid ester of polypropylene oxide polymer, and (c) an organic
acid ester of
an ethylene oxide-propylene oxide block copolymer; wherein the air entrainment
in the
cement composition is reduced relative to a cement composition without the
defoaming
composition. In certain embodiments, the defoaming composition is added to the
cement
composition at 0.01 to 1% by weight of the cement.
[0044] In one embodiment, a method for reducing air entrainment in a cement
composition is provided, the method comprising: adding a defoaming composition
to a
cement composition wherein the defoaming composition comprises two or more
organic
acid ester polymers selected from (a) an organic acid ester of polyethylene
oxide polymer,
(b) an organic acid ester of polypropylene oxide polymer, and (c) an organic
acid ester of
an ethylene oxide-propylene oxide block copolymer; wherein the air entrainment
in the
cement composition is reduced relative to a cement composition without the
defoaming
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composition. In certain embodiments, the defoaming composition is added to the
cement
composition at 0.01 to 1% by weight of the cement.
[0045] In one embodiment, a cement composition comprising: hydraulic cement;
water; and a defoaming composition comprises one or more organic acid ester
polymers
selected from an organic acid ester of polyethylene oxide polymer, an organic
acid ester of
polypropylene oxide polymer, and mixtures thereof, is provided. In certain
embodiments,
the composition may further comprise an organic acid ester of an ethylene
oxide-
propylene oxide block copolymer.
[0046] In one embodiment, a cement composition comprising: hydraulic cement;
water; and a defoaming composition comprises one or more organic acid ester
polymers
selected from (a) an organic acid ester of polyethylene oxide polymer, (b) an
organic acid
ester of polypropylene oxide polymer, and (c) an organic acid ester of an
ethylene oxide-
propylene oxide block copolymer; is provided.
[0047] In one embodiment, a cement composition comprising: hydraulic cement;
water; and a defoaming composition comprises two or more organic acid ester
polymers
selected from (a) an organic acid ester of polyethylene oxide polymer, (b) an
organic acid
ester of polypropylene oxide polymer, and (c) an organic acid ester of an
ethylene oxide-
propylene oxide block copolymer; is provided.
[0048] In a particular embodiment, the hydraulic cement comprises hydraulic
cements comprising calcium, aluminum, silicon, oxygen and/or sulfur; Portland
cements
such as class A, B, C, G, and H cements according to American Petroleum
Institute (API)
specification for materials and testing for well cements; pozzolana cements;
gypsum
cements; phosphate cements; high alumina content cements; slag cements; cement
kiln
dust; silica cements; high alkalinity cements; and combinations comprising at
least one of
the foregoing cements.
[0049] In another embodiment, a method of cementing a subterranean formation
is
provided, the method comprising: displacing a cement composition into the
subterranean
formation, the cement composition comprising hydraulic cement, water, and a
defoaming
composition comprises one or more organic acid ester polymers selected from an
organic
acid ester of polyethylene oxide polymer, an organic acid ester of
polypropylene oxide
polymer, and mixtures thereof; and allowing the cement to set. In certain
embodiments, the
composition may further comprise an organic acid ester of an ethylene oxide-
propylene
oxide block copolymer.
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[0050] In another embodiment, a method of cementing a subterranean formation
is
provided, the method comprising: displacing a cement composition into the
subterranean
formation, the cement composition comprising hydraulic cement, water, and a
defoaming
composition comprises one or more organic acid ester polymers selected from
(a) an
organic acid ester of polyethylene oxide polymer, (b) an organic acid ester of
polypropylene oxide polymer, and (c) an organic acid ester of an ethylene
oxide-propylene
oxide block copolymer; and allowing the cement to set.
[0051] In another embodiment, a method of cementing a subterranean formation
is
provided, the method comprising: displacing a cement composition into the
subterranean
formation, the cement composition comprising hydraulic cement, water, and a
defoaming
composition comprises two or more organic acid ester polymers selected from
(a) an
organic acid ester of polyethylene oxide polymer, (b) an organic acid ester of
polypropylene oxide polymer, and (c) an organic acid ester of an ethylene
oxide-propylene
oxide block copolymer; and allowing the cement to set.
[0052] In certain embodiments, the cement composition comprises pumping the
cement composition into an annular space between the walls of a well bore and
casing during
a primary of a remedial cementing operation. In one embodiment, the hydraulic
cement is
foamed and the defoaming composition is added to the hydraulic cement in an
amount
effective to break the foam, thereby reducing gas entrainment in the hydraulic
cement. In one
embodiment, the defoaming composition is at 0.01 to 1% weight of the hydraulic
cement.
[0053] The cement compositions can include the defoaming compositions
described herein, a cementitious material, and a sufficient amount of fluid to
render the
cement compositions pumpable. Any of a variety of cements suitable for use in
subterranean cementing operations may be used. The cementitious material can
include,
for example, hydraulic cements which set and harden by reaction with water.
Examples of
suitable hydraulic cements include but are not limited to hydraulic cements
comprising
calcium, aluminum, silicon, oxygen and/or sulfur; Portland cements such as
class A, B, C,
G, and H cements according to American Petroleum Institute (API) specification
for
materials and testing for well cements; pozzolana cements; gypsum cements;
phosphate
cements; high alumina content cements; slag cements; cement kiln dust; silica
cements;
high alkalinity cements; and combinations comprising at least one of the
foregoing
cements. Examples of suitable fluids for use in the cement compositions
include, but are
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not limited to, fresh water, produced water, seawater, brine solutions, and
combinations
comprising at least one of the foregoing.
[0054] As deemed appropriate by one skilled in the art, additional additives
can be
added to the cement composition for improving or changing the properties of
the cement.
Examples of such additives include but are not limited to set retarders, fluid
loss control
additives, dispersing agents, set accelerators, and formation conditioning
agents. Other
additives such as bentonite and silica fume can be introduced to the cement
composition to
prevent cement particles from settling to the bottom of the fluid. Further, a
salt such as
sodium chloride or potassium chloride can be added to the cement composition.
[0055] The defoaming compositions described herein can be included in various
flowable end use materials to reduce the amount of entrained gas present in
such materials.
In addition to cement compositions, other examples of such end use materials
include but
are not limited to various water-based wellbore treatment fluids such as
drilling muds,
stimulation fluids, waste treatment compositions, water treatment
compositions, leaching
compositions (e.g. for mining), concrete and constructions materials
applications, and oil
and/or gas separation compositions. The various components of such
compositions would
be apparent to persons of ordinary skill in the art.
[0056] The following examples are presented for illustrative purposes only,
and
are not intended to be limiting.
EXAMPLES
[0057] For the following examples, the polymers are labeled as listed below.
Label Polymer type;
average molecular weight
in parentheses
EO/PO DO an oleic acid
ester of a polyoxyethylene-
polyoxypropylene block copolymer (2528
Daltons)
EO DO' an oleic acid
ester of polyoxyethylene
polymer (828 Daltons)
EO DO2 an oleic acid
ester of polyoxyethylene
polymer (928 Daltons)
EO DO3 an oleic acid
ester of polyoxyethylene
polymer (1128 Daltons)
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PO DO' a dioleic
ester of polyoxypropylene polymer
(1528 Dalions.)
PO DO2 a dioleic
ester of polyoxypropylene polymer
(2528 Dalions.)
PO DO3 a dioleic
ester of polyoxypropylene polymer
(4528 Daltons.)
[0058] Example 1.
[0059] In this example the compressive strength was measured for cement
compositions with a defoaming agent. Tributylphosphate is a common cement
defoamer
and used as a reference to compare the performance of defoaming compositions.
The
defoaming agents arc described in Table 1. Compressive strength data up to 48
hours for
API class A cement with a density of 1800 kg/m3 are shown given in Table 2.
Compressive strength testing was carried out on CTE Model 2000-5 Ultrasonic
Cement
Analyzer according to API RP 10B-2 (Recommended Practice for Testing Well
Cements)
operating at 4000 psi pressure and temperature of 50 C. The results show that
defoamer
containing cements meet the necessary requirements for compressive strength
and that the
defoamer compositions can be used to create viable and useful cement blends.
Minimum
requirement in well cementing is a compressive strength of 3.5 MPa after 48
hours.
[0060] Table 1 ¨ Defoaming compositions used in compressive strength
development study
Label Defoaming Components
Defoamer A Tributylphosphate (100%)
Defoamer B EO DO2 (30%) in Vegetable Oil
Defoamer C EO/P0 DO (30%) in Vegetable Oil
Defoamer D EO/P0 DO (10%) + EO DO2 (20%) in Vegetable Oil
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[0061] Table 2 - Compressive strength development of API Class A Cement
slurries with 0.2% BWOC* defoamer
Compressive Strength (MPa)
Cement Sample 6 hrs 12 hrs 18 hrs 24 hrs 36 hrs 48 hrs
With Defoamer A 5.46 8.59 10.51 11.84 13.24 14.12
With Defoamer B 5.98 9.19 11.11 12.58 14.45 15.23
WithDefoamerC 6.10 9.37 11.25 12.71 14.46 15.57
With Defoamer D 5.29 8.48 10.26 11.63 13.16 14.01
*BWOC = By Weight Of Cement
[0062] Example 2.
[0063] In this example, the effect of defoamer composition on the theology of
API
class A cement blends with density of 1800 kg/m3 was studied using a Fann 35A
viscometer at 25 and 50 C. The slurry was prepared by mixing dry cement and
tap water
on a Waring blender according to API RP 10B-2 and allowed to condition for 20
minutes
using a Chandler Engineering model 1200 Atmospheric Consistometer at the given
temperature. The rheology data is given in Table 3. It has been found that the
defoamer
composition had minimal or no effect on the rheological behavior of cement
slurries.
[0064] Table 3: Rheological behavior of API Class A cement blend with
density of 1800 kg/m3.
Defoamer Temperature Shear Rate (rpm)
0.2 wt% BWOC C 600 300 200 100 6 3
Dial Reading
None 25 56.0 41.0 34.5 26.0 13.0 8.5
PO DO3 25 57.0 42.5 36.0
27.5 13.5 9.5
PO DO2 25 53.0 39.5 33.0
26.0 12.5 9.0
PO DO' 25 57.0 40.0 33.5
25.5 13.0 9.0
None 50 109.0 85.5 76.5 65.5 22.0 14.0
EO DO2 50 84.0 70.5 66.0
55.0 17.5 10.5
PO DO3 50 126.0 114.0 94.5 79.5 21.5 14.5
EO/PO DO 50 106.0 83.0 71.0 61.0 22.0 14.0
EO/PO DO (10%) + 50 113.0 86.5 73.0 59.5 21.0 14.0
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EO DO2 (20%) in Veg. Oil
[0065] Example 3.
[0066] In this example, defoaming characteristics of various diesters of
polyoxyethylene (EO) compositions on API class cement A slurries with design
density of
1650 kg/m3 containing 1% by weight of cement (BWOC) of sodium lignosulfonate
and
20% by weight of water sodium chloride were examined. The diesters were formed
using
oleic acid (designated using DO). Lignosulfonates are commonly used in
formulating
cement slurries as cement dispersing agents. Densities were measured
immediately after
the slurry was prepared (based on API RP 10B-2 procedure) using a graduated
cylinder
and weight of the slurry. Data are graphically represented in Figure 1. All
defoaming
compositions tested were found to be effective on reducing air entrainment
when added at
0.01% to 0.10% BWOC.
[0067] Example 4.
[0068] In this example, defoaming characteristics of various diesters of
polyoxypropylene (PO) compositions on API class cement A slurries with design
density
of 1650 kg/m3 containing 1% BWOC of sodium lignosulfonate and 20% by weight of
water sodium chloride were examined. The diesters were formed using oleic
acid.
Lignosulfonates are commonly used in formulating cement slurries and is
generally known
as cement dispersing agents. Densities were measured immediately after the
slurry was
prepared (based on API RP 10B-2 procedure) using a graduated cylinder and
weight of the
slurry. Data are graphically represented in Figure 2. All defoaming
compositions tested
were found to be effective on reducing air entrainment when added at 0.05% to
0.20%
BWOC.
[0069] Example 5.
[0070] Many cement additives can cause the slurry to foam during mixing
including surface active agents such as dispersants. In this example,
performance of
various defoaming compositions were examined in a highly foaming system
containing
sodium lignosulfonate (1% BWOC), sodium chloride (20% by weight of water) and
API
class A cement with a designed density of 1650 kg/m3. Data are graphically
represented in
Figure 3 and defoaming compositions are described in Table 4. As shown in
Figure 3, in
the absence of defoamer, air entrainment causes the slurry density (1039
kg/m3) to be
significantly lower than the designed density of 1650 kg/m3. In contrast, all
defoamer
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compositions (added at 0.10% BWOC) were effective in antifoaming/defoaming in
such a
system.
[0071] Table 4: Description of defoaming compositions used in Example 5.
Composition # Defoaming Chemistry Diluent
1 10% EO/PO DO & 30% PO DO3 Vegetable Oil
2 20% EO/PO DO & 20% PO DO3 Vegetable Oil
3 30% EO/PO DO & 10% PO DO3 Vegetable Oil
4 10% EO DO2 & 30% PO DO3 Vegetable Oil
20% E0 DO2 & 20% PO DO3 Vegetable Oil
6 30% EO DO2 & 10% PO DO3 Vegetable Oil
[0072] Example 6.
[0073] In this example, the effect of the addition of 0.1% of defoaming
composition by weight of cement (BWOC) on a cement composition containing 1%
BWOC sodium lignosulfonate and 20% by weight of water sodium chloride was
examined. Slurry density was measured immediately after mixing the dry cement
with
brine water and the dispersant. Data are graphically represented in Figure 4
and defoaming
compositions are described in Table 5. As shown in Figure 4, formulations
containing both
diesters of E0 polymers and diesters of EO/PO copolymers were found to be
effective
defoaming agents based on proximity of measured density and design density
data.
[0074] Table 5: Description of defoaming compositions used in Example 6.
Composition # Defoaming Chemistry Diluent
1 20% EO/PO DO Vegetable Oil
2 20% EO DO2
Vegetable Oil
3 20% EO/PO DO & 20% EO DO2 Vegetable Oil
4 30% EO/PO DO & 10% EO DO2 Vegetable Oil
5 10% EO/PO DO & 20% EO DO2 Vegetable Oil
6 20% EO/PO DO & 10% EO DO2 Vegetable Oil
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