Note: Descriptions are shown in the official language in which they were submitted.
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2,4-PENTANEDIONE DISULFONATE SALTS, METHODS FOR THEIR PREPARATION AND THEIR
USE IN CEMENT COMPOSITIONS
Background
The present invention relates generally to salts that are useful as cement
dispersants,
methods for making such salts, cement compositions incorporating such salts,
and methods for
cementing using cement compositions incorporating such salts. The invention
also relates to cement
compositions incorporating such salts. In particular, a disulfonate salt of
2,4-pentanedione and
methods for making and using such a salt are described.
Cement dispersants are often used in cement compositions utilized in
construction for
facilitating the mixing of the cement compositions. Also, in the cementing of
oil and gas wells and
the like, dispersants are extensively used to reduce the apparent viscosities
of the cement
compositions utilized. The reduction of the apparent viscosity of a cement
composition allows the
cement composition to be pumped with less friction pressure and less pump
horsepower. In
addition, the lower apparent viscosity often allows the cement composition to
be pumped in
turbulent flow. Turbulent flow characteristics are desirable when pumping
cement compositions in
oil and gas wells to more efficiently remove drilling fluid from surfaces in
the well bore as the
drilling fluid is displaced by the cement composition being pumped. The
inclusion of dispersants in
cement compositions is also desirable in that the presence of the dispersants
reduces the water
required for preparation of the cement compositions. Cement compositions
having a reduced water
content are characterized by improved compressive strength development.
A number of dispersing agents have been utilized heretofore in cement
compositions,
particularly in cement compositions used for primary and remedial cementing in
oil and gas wells.
For example, certain organic acids, such as gluconic acid and citric acid,
have been used as cement
dispersants. However, such organic acids are also strong set retarding agents.
That is, the presence
of an organic acid dispersant in a cement composition prevents the cement
composition from setting
for a relatively long period of time. Such a delayed set is often costly or
otherwise detrimental.
Other dispersants that are commonly used in hydraulic cement compositions
include polynapthalene
sulfonate, poly-B-naphthol sulfonate, polymelamine sulfonate, and many others.
While such
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2
dispersants function very well in cement compositions, they can be
environmentally unacceptable,
especially in offshore operations where particular ecological properties may
be required.
Description
According to one aspect of the invention, a method of cementing is provided.
The method
includes introducing a cement composition comprising cementitious material,
mixing fluid and a
disulfonate salt of 2,4-pentanedione into an area to be cemented, and allowing
the cement
composition to set therein. In certain embodiments, the 2,4-pentanedione
disulfonate salt acts as a
cement dispersant. According to certain embodiments, the area to be cemented
is in a subterranean
zone, which may be penetrated by a well bore.
According to another aspect of the invention, methods of preparing a
disulfonate salt of 2,4-
pentanedione are provided. According to one such method, 2,4-pentanedione is
sulfonated by
reacting it with a sulfur source, for example, chlorosulfonic acid. The molar
ratio of the sulfur
source to 2,4-pentanedione is in the range of from about 4:1 to about 1:1 in
some embodiments, in
the range of from about 3:1 to about 2:1 in other embodiments, or in the range
of from about 3.5:1
to about 2.5:1 in still other embodiments. The resulting product includes 2,4-
pentanedione-1,5-
disulfonic acid, and other acid by-products, such as hydrochloric and sulfuric
acids, and/or mono-
sulfonic acids.
The resulting product is then reacted with a base, for example, sodium
hydroxide, to
neutralize the 2,4-pentanedione-1,5-disulfonic acid, thereby forming a salt of
2,4-pentanedione.
The amount of base reacted with the resulting product is that amount that will
neutralize at least a
portion of the 2,4-pentanedione-1,5-disulfonic acid. In certain embodiments,
the base is added until
the resulting product is neutralized to a pH of about 7. Any other acids, such
as hydrochloric,
sulfuric, or mono-sulfonic acids that may be present as by-products, may also
be neutralized by
reaction with the base.
The neutralized product is then rinsed with a rinsing agent, for example,
methanol, to
remove other acid by-products, such as hydrochloric and sulfuric acids, and/or
mono-sulfonic acids,
and/or to remove other salts formed by the neutralization, such as salts of
hydrochloric and sulfuric
acids, and/or mono-sulfonic acids. It was discovered that hydrophobic
solvents, such as methanol,
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would remove the by-product acids and/or salts, while leaving the salt of 2,4-
pentanedione-1,5
disulfonic acid primarily undissolved.
According to other examples, the rinsing agent can be another hydrophobic
solvent such as
ethanol, or can be a polar solvent such as dimethylformamide ("DMF"), or can
be any other solvent
that will remove or dissolve the by-products, and not the disulfonate salt.
According to some exemplary methods for preparing a disulfonate salt of 2,4-
pentanedione,
the reaction of 2,4-pentanedione with a sulfur source is conducted in an inert
solvent. The reaction
solvent can be chloroform, or a halogenated hydrocarbon such as carbon
tetrachloride, 1,1,1-
trichloroethane, 1, 1,2-trichloroethane, 1, 1, 1,2-tetrachloroethane and
1,1,2,2-tetrachloroethane.
According to other embodiments for preparing a disulfonate salt of 2,4-
pentanedione, the
reaction of 2,4-pentanedione with a sulfur source is conducted without a
solvent. In still other
examples, the reaction occurs in an inert atmosphere. According to one such
example, the inert
atmosphere comprises nitrogen.
According to some exemplary methods for preparing a disulfonate salt of 2,4-
pentanedione,
the base that is reacted with the reaction product of 2,4-pentanedione and a
sulfur source comprises
an alkali metal or an alkaline earth metal. According to one example of such
methods, the base is
sodium hydroxide, and the neutralization reaction results in the formation of
2,4-pentanedione-1,5-
sodium disulfonate, and may also result in other salts from acid by-products
that may have been
present. According to other embodiments, a potassium salt, a magnesium salt, a
barium salt, an
ammonium salt, a calcium salt or a cesium salt of 2,4-pentanedione is prepared
by reacting the
reaction product of 2,4-pentanedione and a sulfur source with a base derived
from potassium,
magnesium, barium, ammonium, calcium or cesium. Suitable sources include but
are not limited to
hydroxides of potassium, magnesium, barium, ammonium, calcium and cesium. The
resulting salts
would include 2,4-pentanedione- 1, 5 -potassium disulfonate; 2,4-pentanedione-
1,5-magnesium
disulfonate; 2,4-pentanedione-1,5-barium disulfonate; 2,4-pentanedione-l,5-
ammonium
disulfonate; 2,4-pentanedione-1,5-calcium disulfonate; and 2,4-pentanedione-
1,5-cesium
disulfonate, respectively.
According to still other embodiments, sulfonation of 2,4-pentanedione is
achieved using
oleum (fuming sulfuric acid) which is commercially available from numerous
sources including
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4
DuPont. In still other alternative embodiments, sulfonation of 2,4-
pentanedione is achieved
using a falling film sulfur trioxide sulfonation, equipment for which is
commercially available
from sources such as Chemithon Corporation. In still other embodiments, a 2,4-
pentanedione-
1,5-disulfonic acid is prepared as described in U.S. Patent No. 4,987,249 to
Sander, and is
converted to the salt by reaction with a base comprising an alkali metal or an
alkaline earth metal
as described above. Exemplary bases include but are not limited to sodium
hydroxide, potassium
hydroxide, magnesium hydroxide, barium hydroxide, ammonium hydroxide, calcium
hydroxide
and cesium hydroxide.
According to another aspect of the invention, a disulfonate salt of 2,4-
pentaned lone is
provided. According to one such embodiment, the salt comprises 2,4-
pentanedione-1,5-sodium
disulfonate. According to another such embodiment, a disulfonate salt of 2,4-
pentaned lone has
an environmentally acceptable toxicity. As used herein, the term
"environmentally acceptable
toxicity" means that, when tested according to procedures that are the same as
or equivalent to
those set forth by the OSPAR Guidelines for Completing the Harmonised Offshore
Chemical
Notification Format (HOCNF) (References number: 2003-1) that were in effect on
December 31,
2004, the salt is determined to have a toxicity of greater than about 10,000
mg/L for an algae
(skeletonema costatum), a crustacean (acartia tonsa), a fish (scopthalmus) and
a sediment
reworker corophium volutator).
OSPAR is a commission for protection of the marine environment in the North-
East
Atlantic Sea. The HOCNF protocols in effect on December 31, 2004 are known to
those of
ordinary skill in the art, and therefore need not be detailed herein.
Generally, however, the
toxicity tests are conducted with a known number of organisms (e.g., an algae,
a crustacean, a
fish, and a sediment reworker) in a known amount of water. The test substance,
which may be
any of the disulfonate salts of 2,4-pentanedione described herein, is added to
the water until the
organisms die or become incapacitated. The amount of 2,4-pentanedione
disulfonate salt
required to kill or incapacitate half the test population is divided by the
amount of water to give
mg/L.
According to yet another embodiment, a disulfonate salt of 2,4-pentanedione
has a
"nationally acceptable toxicity". As sued herein, the term "nationally
acceptable toxicity" means
that when tested according to procedures that are the same as or equivalent to
those in effect in a
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country of interest on December 31, 2004, the salt is determined to have a
toxicity acceptable for
use in the areas subject to such country's procedures.
According to one such embodiment, a disulfonate salt of 2,4-pentanedione has a
nationally
acceptable toxicity for the United Kingdom. According to this embodiment, the
salt would qualify
5 for a gold ranking under the chemical ranking scheme employed in the United
Kingdom on
December 31, 2004. This chemical ranking scheme uses data established under
the prescreening
criteria set by the Harmonised Mandatory Control System established by OSPAR
and the CHARM
(Chemical Hazard Assessment and Risk Management) algorithm to assign a hazard
quotient to a
chemical, which quotient then correlates with a color on the following color
scale (from most
acceptable to least acceptable): gold, silver, white, blue, orange and purple.
According to another such embodiment, a disulfonate salt of 2,4-pentanedione
has a
nationally acceptable toxicity for Norway. According to this embodiment, the
salt would qualify for
a yellow ranking under the chemical ranking scheme employed in Norway on
December 31, 2004.
Under the Norway ranking scheme, a black ranking indicates that the subject
ingredient cannot be
used in operations in the Norwegian sector of the North Sea, a red ranking
indicates that the subject
ingredient can only be used for a certain period of time in the Norwegian
sector of the North Sea,
and a yellow ranking indicates that the subject ingredient is acceptable for
most operations in the
Norwegian sector of the North Sea. The Norway ranking scheme also uses data
established under
the Harmonised Mandatory Control System, for example the BODIS (Biological
Oxygen Demand
of Insoluble Substance) and log P.,,, (log of the octanol-water partition
coefficient) values of the
subject ingredient. OSPAR, the Harmonised Mandatory Control System, the CHARM
algorithm,
and the ranking schemes of OSPAR member countries such as the United Kingdom
and Norway,
and techniques for evaluating a chemical according to such systems and
schemes, are known to
those of ordinary skill in the art.
A 2,4-pentanedione disulfonate salt as described herein has a variety of uses,
one of which is
as an ingredient in cement compositions. Thus, cement compositions comprising
cementitious
material, mixing fluid and a disulfonate salt of 2,4-pentanedione are
described herein. Such cement
compositions can include any of a variety of cementitious materials, including
but not limited to
hydraulic cements. Hydraulic cements set and harden by reaction with water,
and include Portland
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cements, pozzolan cements, gypsum cements, aluminous cements, silica cements,
and alkaline
cements. According to certain of the present embodiments, the cementitious
material comprises at
least one API Portland cement. As used herein, the term "API Portland cement"
means any cement
of the type defined and described in API Specification 10, 5th Edition, July
1, 1990, of the
American Petroleum Institute, which includes Classes A, B, C, G, and H.
According to certain
examples disclosed herein, the cementitious material comprises any of Classes
G and H cement.
The preferred amount of cementitious material is understandably dependent on
the cementing
operation.
According to certain embodiments, the 2,4-pentanedione disulfonate salt is an
alkaline earth
metal disulfonate salt or an alkali metal disulfonate salt. In particular, the
2,4-pentanedione
disulfonate salt may be selected from the group consisting of 2,4-pentanedione-
l,5-sodium
disulfonate; 2,4-pentanedione-1,5-potassium disulfonate; 2,4-pentanedione-1,5-
magnesium
disulfonate; 2,4-pentanedione-1,5-barium disulfonate; 2,4-pentanedione-1,5-
ainmonium
disulfonate; 2,4-pentanedione-1,5-calcium disulfonate; and 2,4-pentanedione-
1,5-cesium
disulfonate.
The 2,4-pentanedione disulfonate salt can be mixed with the cementitious
material as a dry
ingredient, or can be mixed with the cementitious material as a solution. The
amount of 2,4-
pentanedione disulfonate salt to include in a cement composition depends upon
the application to be
made with the cement composition. However, according to one embodiment, a
disulfonate salt of
2,4-pentanedione is present in a cement composition in an amount effective to
reduce the apparent
viscosity of the cement composition. Thus, a disulfonate salt of 2,4-
pentanedione as described
herein is suitable for use as a dispersant. According to other embodiments, a
disulfonate salt of 2,4-
pentanedione is present in a cement composition in an amount of from about
0.01% to about 5% by
weight of the cementitious material. According to still other embodiments, a
disulfonate salt of 2,4-
pentanedione is present in a cement composition in an amount of from about
0.1% to about 4% or
from about 0.1 % to about 3% by weight of the cementitious material in the
composition.
According to certain examples of cement compositions illustrated herein, the
mixing fluid
comprises water. Preferably, the water is present in an amount sufficient to
make a slurry of a
desired density from a mix comprising cementitious material and a disulfonate
salt of 2,4-
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pentanedione. The water used to form a slurry can be fresh water, unsaturated
salt solution,
including brines and seawater, and saturated salt solution. Generally, any
type of water can be used,
provided that it does not contain an excess of compounds known to those of
ordinary skill in the art
to adversely affect properties of the cement composition. According to one
embodiment, the water
is present in an amount of about 20% to about 200% by weight of the
cementitious material.
According to other embodiments, water is present in an amount of from about
25% to about 150%,
about 30% to about 100%, or about 30% to about 70% by weight of the
cementitious material.
According to another aspect of the invention there is provided a method of
cementing
comprising: introducing a cement composition comprising cementitious material,
mixing fluid, and
a disulfonate salt of 2,4-pentanedione into a subterranean zone; and allowing
the cement
composition to set therein; wherein the disulfonate salt of 2,4-pentanedione
has at least one of an
environmentally acceptable toxicity and a nationally acceptable toxicity.
According to another aspect of the invention there is provided a cement
composition
comprising cementitious material, mixing fluid and a disulfonate salt of 2,4-
pentanedione, wherein
the disulfonate salt of 2,4-pentanedione is selected from the group consisting
of 2,4-pentanedione-
1,5-sodium disulfonate; 2,4-pentanedione-1,5-potassium disulfonate; 2,4-
pentanedione-1,5-
magnesium disulfonate; 2,4-pentanedione-1,5-barium disulfonate; 2,4-
pentanedione-1,5-ammonium
disulfonate; 2,4-pentanedione-1,5-calcium disulfonate; and 2,4-pentanedione-
1,5-cesium
disulfonate, and is present in an amount of from about 0.01% to about 5% by
weight of the
cementitious material.
According to still other exemplary cement compositions, any of a variety of
additives known
to those of ordinary skill in the art may be included. Such additives may
include density modifying
materials (e.g., silica flour, sodium silicate, microfine sand, iron oxides
and manganese oxides),
dispersing agents, retarding agents, accelerating agents, fluid loss control
agents, strength
retrogression control agents, defoaming agents, gas migration agents, flow
enhancing agents,
surfactants, and viscosifying agents.
The following examples are illustrative of the foregoing methods and
compositions.
Example 1
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A disulfonate salt of 2,4-pentanedione was prepared by first adding 575.7 ml
(1009.2 g, 8.66
mol) of chlorosulfonic acid to about 1L of chloroform in a 3L round bottom
flask equipped with a
nitrogen adapter to maintain an inert atmosphere, a water condenser (to
minimize chloroform
evaporation), and another nitrogen adapter to vent liberated gases.
The resulting solution was cooled to 0 C, and 403.8n-d (393.7 g, 3.93 mol) of
2,4-
pentanedione was slowly added via a pressure-equalized slow addition funnel.
The solution was
stirred and maintained at 0 C throughout the addition process. After
completing the addition of the
2,4-pentanedione, the temperature of the solution was raised to 60 C, and the
solution was stirred
overnight.
During the temperature increase, hydrochloric acid was liberated and was
vented into a fume
hood. After the hydrochloric acid evolution ceased, the reaction mixture was
stirred while slowly
cooling to room temperature. The resulting dark red viscous liquid was
quenched with about 1L of
water and separated from the chloroform via a separatory funnel to result in
an acid product that
included 2,4-pentanedione-l,5-disulfonic acid, hydrochloric and sulfuric
acids. The acid product
was then neutralized to a pH of about 7, which resulted in the formation of
2,4-pentanedione-l,5-
sodiuin disulfonate. The neutralization was performed by slowly adding 314.4
grains (about 2
molar equivalents of the 2,4-pentanedione-l,5-disulfonic acid) of sodium
hydroxide under
atmospheric conditions. The reaction is extremely exothermic, therefore the
sodium hydroxide was
added slowly so that atmospheric conditions could be maintained. The
hydrochloric and sulfuric
acid by-products can be neutralized into NaCI (from the hydrochloric acid) and
Na2SO4 (from the
sulfuric acid) with additional sodium hydroxide.
The neutralized product was then rinsed several times with methanol to remove
by-product
acids, or any salts formed therefrom, while leaving the 2,4-pentanedione- 1, 5
-sodium disulfonate
primarily undissolved. When compared to the 2,4-pentanedione-1,5-disulfonic
free acid, the 2,4-
pentanedione-l,5-disulfonic salt was significantly less soluble, which was
unexpected because with
many substances, like aromatic salts, the salt is more soluble than the free
acid. The rinsed product
was dried in a vacuum oven and filtered through a 300 mesh screen to afford a
flowing pale
orange/red powder. The resulting powder was 2,4-pentanedione-1,5-sodium
disulfonate.
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The particular amounts recited in this Example 1 are illustrative only, as
amounts other than
those recited above can be used to render molar ratios of reaction and/or
neutralization ingredients
suitable for preparing a disulfonate salt of 2,4-pentanedione as disclosed
herein.
Example 2
Example 2 illustrates an exemplary use for a 2,4-pentanedione disulfonate
salt. While the
salt has other utilities, this Example 2 illustrates use of the salt as a
dispersant in cement
compositions.
Sixteen cement compositions (Composition Nos. 1 - 16) and certain properties
of such
compositions are described in Table 1. Each of the compositions was prepared
from a base of
100% cementitious material. The cementitious material for Composition Nos. 1-
12 and 15-16 was
API Class G cement obtained from Dyckerhoff AG. The cementitious material for
Composition
No. 13 was API Class H cement obtained from LaFarge Corp.'s Joppa plant in
Illinois. The
cementitious material for Composition No. 14 was API Class H cement obtained
from Texas
Industries, Inc. ("TXI").
A dispersant and other additives (where indicated) were added to the base of
each cement
composition (i.e., to the cementitious material) in the amounts reported in
Table 1, where "% bwoc"
indicates a weight percentage by total weight of the cementitious material.
Dispersant Type A used for Composition Nos. 1, 5, 7, 10, 11 and 13 - 16
comprised a
disulfonate salt of 2,4-pentanedione as a dispersant. The 2,4-pentanedione
disulfonate salt used for
the compositions of Example 2 was 2,4-pentanedione-1,5 sodium disulfonate
prepared according to
Example 1, however, a 2,4-pentanedione disulfonate salt can be obtained by
other methods as
discussed herein.
Dispersant Type B used for Composition Nos. 2, 6 and 8 comprised a
condensation product
of formaldehyde, acetone and a sulfite, which is a known dispersant
commercially available under
the tradename CFR-3TM from Halliburton Energy Services, Duncan, Oklahoma.
Dispersant Type C used for Composition Nos. 3 and 9 comprised a phenolic
hydroxyl group
blocked alkali metal lignosulfonate, which is a known dispersant commercially
available under the
tradename CFR-5TM from Halliburton Energy Services, Duncan, Oklahoma.
Composition Nos. 4 and 12 did not include a dispersant.
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Other Additive Type D, used for Composition Nos. 1- 3, comprised a grafted
lignin as a
retarder, which is commercially available under the tradename FDP601TM from
Halliburton Energy
Services, Duncan, Oklahoma.
Other Additive Type E indicates a group of additives, each available from
Halliburton
5 Energy Services, Duncan, Oklahoma, that were used to form Composition Nos. 7-
9. The additives
indicated by Type E according to the embodiments illustrated by Composition
Nos. 7-9 comprised:
0.5 % bwoc of a gas migration agent comprising silica, which is available
under the tradename
GasconTM; 1.1 % bwoc of a retarder comprising a refined lignosulfate, which is
available under the
tradename HR-5LTM; 0.2 % bwoc of a defoaining agent comprising a seed oil and
surfactants,
10 which is available under the tradename NF-6TM; 0.1 % bwoc of a flow
enhancing agent comprising
a silica supported acid, which is commercially available under the tradename
EZF10TM; 5.5 % bwoc
of a fluid loss agent comprising a cellulose, which is commercially available
under the tradename
Halad 613TM; and 2.2 % bwoc of a fluid loss agent comprising a grafted acrylic
polymer, which is
commercially available under the tradename Halad 600TH. Each additive in the
group of additives
indicated by the designation "E" was mixed with the cement, dispersant, and
mixing fluid to form
Composition Nos. 10 - 12.
Other Additive Type F, used for Composition Nos. 10 - 11, comprised a refined
lignosulfonate, which is commercially available as a retarder under the
tradename HR-5 from
Halliburton Energy Services, Duncan, Oklahoma.
The procedure followed for preparing each cement composition with the
cementitious
materials, dispersant, additives and mixing fluid as described above was API
Specification RP 1013,
22nd Edition, 1997, of the American Petroleum Institute, which is a
specification known to those of
ordinary skill in the art. Generally, according to said specification, the
cementitious material,
dispersant and other additive (where applicable) were dry-blended (the "dry
blend") and then added
over a 15 second period to mixing fluid being maintained in a blender at 4000
RPM. When all of
the dry blend was added to the mixing fluid, a cover was placed on the blender
and mixing was
continued at about 12,000 RPM for about 35 seconds. For each cement
composition, the mixing
fluid comprised water in the amount as listed in Table 1, where "% bwoc"
indicates a weight
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percentage by total weight of the cementitious material. The density (lb/gal)
of each composition is
reported in Table 1.
The plastic viscosity ("PV"), yield point ("YP") and thickening time ("TT")
were also tested
for the compositions indicated in Table 1, at the test temperatures indicated
in Table 1. Each of the
plastic viscosity, yield point and thickening time was tested (where
indicated) according to
procedures well known to those of ordinary skill in the art, and which are
described in API
Specification RP 1OB, 22nd Edition, 1997, of the American Petroleum Institute.
In Table 1, the
results of the PV tests are reported in centipoises and the results of the YP
tests are reported in
Pascals. The results of the TT tests are reported in time (hours:minutes) that
it took the composition
to attain 100 Bearden units of consistency (BC) in a high pressure
consistometer, determined as
described in API Specification RP 10B referenced above.
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TABLE 1
No. Mixing Dispersant Other Density Test PV YP TT
Fluid Type and Additive (lb/gal) Temp (cp) (Pascal) Hrs:Mins
(% bwoc) Amount Type and ( F)
(% bwoc) Amount
bwoc)
1 35 A D 16.92 80 96 8.2 not tested
0.2 0.1
2 35 B D 16.92 80 89 1 not tested
0.2 0.1
3 35 C D 16.92 80 127.4 7.4 not tested
0.2 0.1
4 41.80 none none 16.14 80 55 11 3:28
41.80 A none 16.10 80 31 6 5:19
0.684
6 41.80 B none 16.10 80 settle settle 8:38
0.684
7 41.80 A E 14.99 122 35.6 2 5:15
0.684
8 41.80 B E 14.99 122 45.4 0 7:30
0.684
9 41.80 C E 14.99 122 46.7 0 9:07
0.684
41.80 A F 16.09 122 34.9 9.8 3:02
0.684 0.15
11 41.80 A F 16.09 122 27.8 11.3 2:50
0.684 0.11
12 41.80 none none 16.14 122 not not tested 2:01
tested
13 32 A none 17.31 80 44.8 5.9 not tested
0.45
14 29 A none 17.75 80 200 10 not tested
0.50
41.80 A none 16.10 122 65 16.9 2:38
0.684
16 41.80 A none 16.10 122 66.4 11.8 2:29
0.684
Those of ordinary skill in the art understand that the presence of a
dispersant in a cement
composition affects the PV of the composition, as well as the YP. PV and YP
indicate rheological
5 properties of a cement composition, where PV is related to the mechanical
friction between particles
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and YP is related to the force required to break interactive bonds between
particles and then to
produce movement. In any given application, it may be desirable to increase or
decrease the PV or
the YP of a cement composition to achieve rheological properties suitable for
that application.
Those of ordinary skill in the art understand that a desirable value for
either PV or YP depends on
the application (for example, the type of cementing being performed and the
conditions under which
the cementing will occur) being made with the cement composition. Generally,
however, those of
ordinary skill in the art understand that the thickness of a cement
composition varies in direct
relationship to the PV value of the cement composition. Cement compositions
that are too thick for
a given application have flowability problems. Thus, a desirable PV for a
cement composition is
one that, for a given application, is low enough to avoid flowability
problems, but high enough to
provide the cement composition with the desired rheological property for the
given application. As
to YP, those of ordinary skill in the art understand that, generally, the
lower the YP of cement
composition, the more likely it is that the constituents of the composition
will settle out. Thus, a
desirable YP is one that is high enough to prevent settling, but low enough to
provide the cement
composition with the desired rheological property for the given application.
Considering that a desirable value for either PV or YP depends on the
application being
made with the cement composition, the PV and YP data for Composition Nos. 1,
5, 7, 10, 11 and 13
- 16 illustrate that cement compositions that include a dispersant comprising
a disulfonate salt of
2,4-pentanedione exhibit favorable rheological properties as compared to
cement compositions
comprising conventional dispersants (i.e., Composition Nos. 2, 3, 6, 8 and 9.)
In particular, a comparison between Composition Nos. 1 - 3, each of which
comprised a
different Dispersant Type, in equal amounts respectively, and the same Other
Additive Type
amount, in equal amounts, shows that Composition No. 1 (which comprised a
disulfonate salt of
2,4-pentanedione and Additive Type D) has a PV value less than that of
Composition No. 3 (which
comprised CFR-5TM dispersant and Additive Type D), but a YP value greater than
that of No. 3,
thus making Composition No. 1 a more suitable cement composition for certain
applications. As
between Composition No. 2 (which comprised CFR-3TM dispersant and Additive
Type D) and
Composition No. 1, Composition No. 1 has a greater PV and larger YP value,
thus making
Composition No. 1 a more suitable cement composition for certain applications.
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14
Composition No. 4, which included only water and cement, provides a control
for
comparison of compositions that included water, cement, and one of Dispersant
Types A, B and C,
such as Compositions Nos. 5 and 6. For example, a comparison between the PV,
YP and TT values
of Composition Nos. 4, 5 and 6 illustrates that cement compositions that
include a disulfonate salt
of 2,4-pentanedione (Dispersant Type A) have rheological properties and
thickening times that
make them more suitable for certain applications than cement compositions that
do not include a
disulfonate salt of 2,4-pentanedione (Composition No. 4), or that include a
different Dispersant
Type (Composition No. 6).
Further, Composition Nos. 5 and 6 are useful for comparing cement compositions
that
include, respectively, a disulfonate salt of 2,4-pentanedione as a dispersant
(Dispersant Type A) and
a conventional dispersing agent (Dispersant Type B), in equal amounts. The PV
and YP data
indicate that Composition No. 5 did not settle, while Composition No. 6 did.
Those of ordinary
skill in the art understand that settling is an undesirable occurrence for a
cement composition. Thus,
the PV and YP data indicate that a dispersant comprising a disulfonate salt of
2,4-pentanedione
(Dispersant Type A) contributes favorable rheological properties to a cement
composition.
Moreover, the TT of Composition No. 5 was approximately 3 hours less than that
of Composition
No. 6. A shorter TT is desirable in certain cement applications, thus making a
cement composition
such as Composition No. 5 more suitable for certain applications.
Composition Nos. 7 - 9 illustrate compositions comprising the same type and
amount of
Other Additive (Type E), but equal amounts of different Dispersant Types. The
PV and YP data
indicate that Composition No. 8 (which comprised CFR-3TM dispersant and
Additive Type E)
exhibits PV and YP properties substantially similar to that of Composition No.
9 (which comprised
CFR-5TM dispersant and Additive Type E). Composition No. 7, however, (which
comprised a
disulfonate salt of 2,4-pentanedione and Additive Type E) has a lower PV
value, but a larger YP
value, thus making Composition No. 7 more suitable than Composition Nos. 8 and
9 for certain
applications. Moreover, the TT of Composition No. 7 was shorter than that of
Composition Nos. 8
and 9, which makes a cement composition such as Composition No. 7 more
suitable for
applications where it is desirable to have a shorter TT.
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Composition Nos. 10 - 11 illustrate compositions comprising equal amounts of
Dispersant
Type A (a disulfonate salt of 2,4-pentanedione), but different amounts of
Other Additive Type F (a
refined lignosulfonate retarder). Composition Nos. 10 and 11 illustrate that
conventional retarders,
such as Type F, are effective in cement compositions comprising a salt of 2,4-
pentanedione. Such
5 cement compositions achieve favorable rheological properties as indicated by
the reported YP and
PV values, and the retarder still functions to slow the TT's of such
compositions.
Thus, the TT's of cement compositions that include a disulfonate salt of 2,4-
pentanedione
can be adjusted with conventional retarders. In any given application, it may
be desirable to have a
longer or shorter TT. The TT of Composition No. 12, which included only water
and cement,
10 provides a control for comparison of compositions that included Dispersant
Type A, and optionally,
retarding agents. For example, the TT of Composition Nos. 10 and 11 (each of
which included a
retarding agent) is longer than that of Composition No. 12. The TT of
Composition Nos. 15 and 16
(each of which did not include a retarding agent) is also longer than that of
Composition No. 12,
although not as long as Composition Nos. 10 and 11.
15 Composition Nos. 13 - 16 illustrate compositions that include a disulfonate
salt of 2,4-
pentanedione as a dispersant in varying amounts. The PV and YP data for each
of these
compositions illustrate that the disulfonate 2,4-pentanedione salt is an
effective dispersant in
varying amounts over a broad temperature range. The amount of a disulfonate
salt of 2,4-
pentanedione to include in a cement composition as a dispersant according to
the present
embodiments depends upon the application to be made with the cement
composition. However,
according to one embodiment, a dispersant comprising a disulfonate salt of 2,4-
pentanedione is
present in a cement composition in an amount effective to reduce the apparent
viscosity of the
cement composition.
Example 3
Example 3 illustrates an exemplary use for a 2,4-pentanedione disulfonate salt
as an
ingredient in cement compositions required to comprise ingredients meeting an
environmentally
acceptable toxicity or a nationally acceptable toxicity. A 2,4-pentadionedione
disulfonate salt as
described herein was determined to have an environmentally acceptable toxicity
and a nationally
acceptable toxicity. In particular, 2,4-pentanedione-1,5-sodium disulfonate
prepared according to
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Example I was determined to have a toxicity of greater than about 10,000 mg/L
for an algae
(skeletonema costatum), a crustacean (acartia tonsa), a fish (scopthalmus) and
a sediment reworker
(corophium volutator).
In this Example 3, the toxicity results for the skeletonema costatum were
determined
according to ISO (International Organization for Standardization) 10253, the
protocol for which is
known to those of ordinary skill in the art, and is also the protocol required
under the above-
referenced HOCNF Guidelines. The toxicity results for the acartia tonsa were
determined according
to ISO 14669, the protocol for which is known to those of ordinary skill in
the art. The toxicity
results for the scopthalmus and the corophium volutator were determined
according to Part B of the
OSPAR Protocols on Methods for the Testing of Chemicals Used in the Offshore
Industry
(published by OSPAR in 1995).
A toxicity result of greater than about 10,000 mg/L for the species tested in
this Example 3
indicates that 2,4-pentanedione-1,5-sodium disulfonate has a low toxicity such
that it would have an
environmentally acceptable toxicity and/or a nationally acceptable toxicity in
at least one country of
interest, for example the United Kingdom or Norway. Such toxicity
acceptability makes 2,4-
pentanedione-l,5-sodium disulfonate particularly useful for compositions
required to meet a
particular environmental standard. Other 2,4-pentanedione disulfonate salts as
described herein
should also have low toxicity such that they would have an environmentally
acceptable toxicity
and/or a nationally acceptable toxicity in at least one country of interest.
Other embodiments of the current invention will be apparent to those skilled
in the art from
a consideration of this specification or practice of the invention disclosed
herein. However, the
foregoing specification is considered merely exemplary of the current
invention. It will be
appreciated that the invention may be modified within the spirit and scope of
the claims.
