Note: Descriptions are shown in the official language in which they were submitted.
CA 02680392 2009-09-09
WO 2008/113975 PCT/GB2008/000847
I
PARTICULATE FLOW ENHANCING ADDITIVES AND ASSOCIATED METHODS
BACKGROUND
[0001] The present invention generally relates to additives for particulate
materials, such as cementitious materials and non-cementitious materials. More
specifically,
the present invention relates to compositions that may improve the flow
properties of dry
particulate cementitious and non-cementitious materials and related methods of
synthesis and
use.
[0002] Cementitious materials such as hydraulic cements, slag, fumed silica,
fly ash aild the like having various particle size distributions are often dry-
blended and placed
in storage tanks. The storage tanks containing the cementitious materials are
often
transported by land or sea to locations where the cementitious materials are
to be used.
During such transportation, the cementitious materials are subjected to
vibrations and as a
result, under static conditions, the materials can become tightly packed. When
the
cementitious materials are conveyed out of the storage tanks, significant
portions of the
tightly packed materials may unintentionally be left behind in the storage
tanks or clumps of
the packed materials may become lodged in transfer conduits. Beyond the cost
of the
unusable cementitious materials, costly removal and disposal procedures may be
required to
remove the packed materials from the storage tanks or transfer conduits.
[0003] Treatments have been developed to reduce the likelihood that
cementitious and non-cementitious materials will pack by improving or
preserving the flow
properties of the materials. Certain treatments involve blending dry
particulate cementitious
and/or non-cementitious materials with an additive. One such additive
comprises a
particulate solid adsorbent material having a flow inducing chemical adsorbed
thereon. In
general, these additives are dry-blended with cementitious and/or non-
cementitious materials
at a point in time before packing is likely to occur, e.g., before the
materials are shipped or
stored. Typically, the dry-blending step occurs at a location other than the
location where the
cementitious or non-cementitious materials are ultimately utilized. For
example, an additive
may be dry-blended with cementitious materials in a warehouse before the blend
is
transported to a second location where it is used in a cementing operation.
[0004] While additives comprising a flow inducing chemical adsorbed onto a
particulate solid adsorbent material may improve the flow properties of
cementitious and
non-cementitious materials, certain undesirable properties of the additives
may complicate or
CA 02680392 2009-09-09
WO 2008/113975 PCT/GB2008/000847
2
limit their use. In particular, known additives may conglomerate and/or freeze
at relatively
high temperatures. For example, the additives may begin to conglomerate at
temperatures as
high as 60 F. In other cases, additives may freeze at temperatures as high as
55 F. When
completely frozen, an additive may lose its free-flowing, powder-like
consistency and take
the form of a solid, rock-like mass. This may be a tremendous disadvantage,
because until
the temperature of the additive can be raised, it may be difficult or
impossible to dry-blend
the additive with cementitious or non-cementitious materials. Typically, an
additives' low
freezing point may be most problematic prior to the point when the additive is
dry-blended
with another material, e.g. when the additive is still in a relatively pure
form. Due to the low
freezing point of some additives, in cold climates the additives may have to
be produced
and/or stored in climate-controlled facilities, e.g., climate-controlled
warehouses. If climate-
controlled facilities are not available or are not cost effective, the
additives may freeze and
become at least temporarily unusable, because they cannot be dry-blended with
cementitious
or non-cementitious materials in a frozen state. In some cases, the freezing
points of the
individual components of the additive may be even higher than the freezing
point of the
finished additive, e.g., certain components may have freezing points above 60
F, so the
components may freeze while the additive is being manufactured, making it
difficult or
impossible to produce the finished additive.
SUMMARY
[0005] The present invention generally relates to additives for particulate
materials, such as cementitious materials and non-cementitious materials. More
specifically,
the present invention relates to compositions that may improve the flow
properties of dry
particulate cementitious and non-cementitious materials and related methods of
synthesis and
use.
[0006] In one aspect, the present invention provides compositions comprising:
a particulate solid adsorbent material; a flow inducing chemical; water; and
ethylene glycol.
[0007] In another aspect, the present invention provides methods comprising:
providing a flow enhancing additive comprising a flow inducing chemical, a
solid adsorbent
particulate material, ethylene glycol, and water; providing a cementitious
material, a non-
cementitious material, or a mixture of cementitious and non-cementitious
material; and
blending the flow enhancing additive with the cementitious material, the non-
cementitious
material, or the mixture of cementitious and non-cementitious material.
CA 02680392 2009-09-09
WO 2008/113975 PCT/GB2008/000847
3
[0008] In another aspect, the present invention provides methods comprising:
providing a cementitious material, a non-cementitious material, or a mixture
of cementitious
and non-cementitious material comprising a flow enhancing additive, wherein
the flow
enhancing additive comprises a flow inducing chemical, a solid adsorbent
particulate
material, ethylene glycol, and water; allowing the cementitious material, non-
cementitious
material, or the mixture of cementitious and non-cementitious material to
interact with a
sufficient amount of water to form a pumpable slurry; and placing the pumpable
slurry in a
subterranean formation.
[0009] The features and advantages of the present invention will be readily
apparent to those skilled in the art. While numerous changes may be made by
those skilled in
the art, such changes are within the spirit of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] The drawings illustrate certain aspects of some of the embodiments of
the present invention, and should not be used to limit or define the
invention.
[0011] FIGURE 1 shows the change in the viscosity of a cement slurry over
time.
[0012] FIGURE 2 shows the change in the viscosity of a cement slurry over
time.
DESCRIPTION OF PREFERRED EMBODIMENTS
[0013] The present invention generally relates to additives for particulate
materials, such as cementitious materials and non-cementitious materials. More
specifically,
the present invention relates to compositions that may improve the flow
properties of dry
particulate cementitious and non-cementitious materials and related methods of
synthesis and
use.
[0014] In some aspects, the present invention relates to additives for
cementitious and non-cementitious materials and related methods of using
cementitious and
non-cementitious materials which comprise these additives. In some
embodiments, the
present invention generally provides compositions that may impart desired flow
properties to
dry particulate cementitious materials, non-cementitious materials, or a
mixture of a
cementitious and non-cementitious materials. These compositions are broadly
referred to
herein as "flow enhancing additives." In some embodiments, the flow enhancing
additives of
the present invention may have a lower freezing point than previously known
flow enhancing
CA 02680392 2009-09-09
WO 2008/113975 PCT/GB2008/000847
4
additives. Of the inany potential advantages of the flow enhancing additives
of the present
invention, one advantage may be that the freezing point of the flow enhancing
additives may
be downwardly adjustable to a desired temperature by varying the relative
amounts of the
substances that malce up the additives. One benefit of a depressed freezing
point may be that
the flow enhancing additive may be stored at temperatures at which previously
known
additives conglomerate or freeze into a solid mass. In particular, the need
for climate-
controlled storage of concentrated forms of the flow enhancing additives may
be eliminated.
[0015] The flow enhancing additives of the present invention may comprise a
particulate solid adsorbent material, a flow inducing chemical, ethylene
glycol, and water.
[0016] Particulate solid adsorbent materials that are suitable for use in the
flow enhancing additives of the present invention may comprise any particulate
adsorbent
solid that does not negatively interact with other components of the flow
enhancing additive.
In preferred embodiments, suitable particulate solid adsorbent materials are
capable of
adsorbing the flow inducing chemical(s) utilized in the flow enhancing
additive. Examples
of such adsorbent materials include, but are not limited to, precipitated
silica, zeolite, talcum,
diatomaceous earth fuller's earth, derivatives thereof, and combinations
thereof. Of these,
precipitated silica is presently preferred. One example of a commercially
available
precipitated silica that is suitable for use in the flow enhancing additives
of the present
invention is available under the tradename "Sipernat-22TM" from Degussa GmbH
of
Dusseldorf, Germany.
[0017] Flow inducing chemicals that are suitable for use in the present
invention may comprise any chemical that interacts or reacts with cementitious
and/or non-
cementitious materials in such a way that a relative increase in the flow
properties of the
cementitious and/or non-cementitious materials may be observed. In certain
embodiments,
preferred flow inducing chemicals produce polar molecules. While the ability
of the flow
inducing chemicals to increase the flow properties of cementitious and non-
cementitious
materials is not fully understood (and therefore not wanting to be limited to
any particular
theory), it is believed that in the case of flow inducing chemicals that
produce polar
molecules, the polar molecules react or interact with components of the
cementitious and/or
non-cemeiltitious materials (e.g., tricalcium silicate) to create a particle
repulsion effect in the
cementitious and/or non-cementitious materials. Examples of suitable flow
inducing
chemicals include, but are not limited to, organic acids such as alkyl and/or
alkene carboxylic
acids and sulfonic acids, salts of the foregoing acids formed with weak bases,
acid anhydrides
CA 02680392 2009-09-09
WO 2008/113975 PCT/GB2008/000847
such as sulfur dioxide, carbon dioxide, sulfur trioxide, nitrogen oxides and
similar
compounds, derivatives thereof, and combinations thereof. In preferred
embodiments, the
flow inducing chemical is adsorbed onto the particulate solid adsorbent
material utilized in
the flow enhancing additive. One preferred flow inducing chemical for use in
accordance
with the present invention is glacial acetic acid. In some embodiments,
certain particulate
solid adsorbent materials, e.g., some zeolites, may serve as suitable flow
inducing chemicals
by reducing the tendency of the cementitious or non-cementitious materials to
pack. In a
subset of those embodiments, the solid adsorbent material utilized in the flow
enhancing
additive may serve a dual-function as the solid adsorbent material and the
flow inducing
chemical. In the embodiments in which the solid adsorbent material serves a
dual function,
the flow inducing chemical may not be adsorbed onto the solid adsorbent
material, because
the solid adsorbing material and the flow inducing chemical are one in the
same. In sonle
embodiments, the ability of particulate solid adsorbent materials to reduce
packing of
cementitious and/or non-cementitious materials may be the result of the
formation of a solid
crystal lattice structure between the particulate materials.
[001 8] According to certain embodiments of the present invention, the weight
ratio of particulate solid adsorbent material to flow enhancing chemical in
the flow inducing
additive is generally in the range of from about 90:10 to about 10:90, more
preferably in the
range of from about 75:25 to about 25:75. Other ranges may be suitable as
well. In one
exemplary embodiment, the particulate solid adsorbent material and the flow
enhancing
chemical are present in approximately equal amounts by weight.
[0019] The water used in the flow enhancing additives of the present
invention may comprise fresh water, saltwater (e.g., water containing one or
more salts
dissolved therein), brine, seawater, or combinations thereof. Generally, the
water may be
from any source, provided that it does not contain components that might
adversely affect the
stability and/or performance of the additives of the present invention.
[0020] Ethylene glycol may be present in the flow enhancing additive in an
anlount ranging from about 10% to about 150% by weight of the water present in
the flow
enhancing additive. According to some embodiments, the ethylene glycol may be
present in
an amount ranging from about 10% to about 100% by weight of the water. In some
embodiments, the total coinbined amount of ethylene glycol and water present
in the flow
enhancing additive is an amount sufficient to lower the freezing point of the
flow enhancing
additive to a desired temperature. The relative amounts of ethylene glycol and
water and/or
CA 02680392 2009-09-09
WO 2008/113975 PCT/GB2008/000847
6
the total combined amount of ethylene glycol and water present in the flow
enhancing
additive may depend upon a number of factors, including the flow inducing
chemical utilized
in the flow enhai7cing additive, the particulate solid adsorbent material
utilized in the flow
enhancing additive, the relative amounts of flow inducing chemical to
particulate solid
adsorbent material, the freezing points of the particulate solid adsorbent
material and the flow
enhancing chemical in the absence of ethylene glycol and water, and the
desired freezing
point of the flow enhancing additive. A person of ordinary skill in the art
may be able to
appreciate the relative amounts of ethylene glycol and water and/or the total
combined
amounts of ethylene glycol and water necessary to lower the freezing point of
the flow
enhancing additive to a desired temperature.
[00211 In some embodiments, the flow enhancing additives of the present
invention may have a lower freezing point than combinations of similar amounts
of
particulate solid adsorbent material and flow inducing chemical in the absence
of water and
ethylene glycol. Although the mechanism by which the freezing point of a flow
enhancing
additive of the present invention is depressed is not fully understood, it is
thought that the
water present in the flow enhancing additive may form hydrogen bounds with the
flow
inducing chemical so that the freezing point of the flow inducing chemical is
lowered. In
addition, the ethylene glycol may interact with the water to lower the
freezing point of the
water. It is believed that this system of interactions is responsible for
depressing the overall
freezing point of the flow enhancing additive.
[0022] In certain embodiments, the flow enhancing additives of the present
invention are dry-blended with cementitious materials. Generally, the
cementitious material
may be any cementitious material that is suitable for use in cementing
operations.
Cementitious materials that are suitable for use in the present invention
include, but are no
limited to, hydraulic cements, slag, fumed silica, fly ash, mixtures thereof,
and the like. A
variety of hydraulic cements are suitable for use, including those comprising
calcium,
aluminum, silicon, oxygen, and/or sulfur, which may set and harden by reaction
with water.
Such hydraulic cements include, for example, Portland cements, pozzolanic
cements, gypsum
cements, high alumina content cements, silica cements, high alkalinity
cements, slag
cements, Sorel cements, cement kiln dust, vitrified shale, derivatives
thereof, and
combinations thereof. As referred to herein, the term "fly ash" refers to the
finely divided
residue that results from the combustion of ground or powdered coal and is
carried by the
flue gases generated thereby. "Cement kiln dust," as that term is used herein,
refers to a
CA 02680392 2009-09-09
WO 2008/113975 PCT/GB2008/000847
7
partially calcined kiln feed which is typically removed from the gas stream
and collected in a
dust collector during the manufacture of cement. In certain preferred
embodiments, the
cementitious material comprises a hydraulic cement that comprises a Portland
cement.
[0023] In some embodiments, the flow enhancing additives of the present
invention are dry-blended with non-cementitious materials. Non-cementitious
materials
suitable for use in the present invention include any non-cementitious
materials which would
not adversely interact with the flow enhancing additives of the present
invention. Particularly
suitable non-cementitious materials include non-cementitious materials which
have a
tendency to demonstrate reduced flow properties over some period of time in
the absence of a
flow enhancing additive. Examples of suitable non-cementitious materials for
use with the
flow enhancing additives of the present invention include, but are not limited
to, barite,
bentonite, lost circulation materials, tensile strength enhancers, elastomers,
metal oxides,
gypsum, derivatives thereof, combinations thereof, and the like.
[0024] Any suitable method for making the flow enhancing additives of the
present invention may be employed. As an example, in another aspect, the
present invention
provides methods of making a flow enllancing additive having a depressed
freezing point
comprising adsorbing a flow inducing chemical on a particulate solid adsorbent
material,
providing ethylene glycol and water in the presence of the flow inducing
chemical, and
allowing the water to interact with the flow inducing chemical and the
ethylene glycol.
[0025] According to some embodiinents of the methods of making a flow
enhancing additive, one or more of the flow inducing chemical, ethylene
glycol, and water
may be premixed before the mixture is exposed to the particulate solid
adsorbent material.
For example, according to some embodiments, the flow inducing chemical,
ethylene glycol,
and water are premixed and then the mixture is exposed to particulate solid
adsorbent
materials so that the flow inducing chemical adsorbs onto the particulate
solid adsorbent
materials. According to certain other embodiments, the flow inducing chemical
is first
exposed to the particulate solid adsorbent material, and ethylene glycol and
water are later
added and evenly distributed therein. For example, ethylene glycol and water
may be added
to a pre-made flow enhancing composition. One example of a suitable pre-made
flow
enhancing composition is cominercially available under the trade name "EZ-FLO"
from
Halliburton Energy Services, Inc. of Duncan, Oklahoma.
[0026] Still another aspect of the invention provides methods of using a flow
enhancing additive to improve the flow properties of cementitious and/or non-
cementitious
CA 02680392 2009-09-09
WO 2008/113975 PCT/GB2008/000847
8
materials comprising: providing a flow enhancing additive comprised of a flow
inducing
chemical, a solid adsorbent particulate material, ethylene glycol, and water;
providing a
cementitious material, a non-cementitious material, or a mixture of
cementitious and non-
cementitious material; and blending the flow enhancing additive with the
cementitious
material, the non-cementitious material, or the mixture of cementitious and
non-cementitious
material. According to some embodiments, the amount of flow enhancing additive
blended
with the cementitious or non-cementitious material is an amount in the range
of from about
0.005% to about 5% by weight of the cementitious or non-cementitious
materials, more
preferably in the range of from about 0.01 % to about 1%, and most preferably
in an ainount
in the range of from about 0.02% to about 0.5%. One of ordinary skill in the
art will
recognize the appropriate amount to use for a chosen application. In certain
embodiments,
the amount of flow enhancing additive blended with the cementitious and/or non-
cementitious material is an amount sufficient to improve or preserve the flow
properties of
the material after a period of storage in a storage tank.
[0027] The flow enhancing additives of the present invention may be dry-
blended with cementitious and/or non-cementitious materials through any method
known in
the art to be suitable for dry-blending. In preferred embodiments, the flow
enhancing
additive is dry-blended with cementitious and/or non-cementitious materials by
boxing the
materials. In general, boxing comprises alternating between blowing portions
of
cementitious and/or non-cementitious materials and portions of flow enhancing
additive into
a common container. The contents of the common container are then transferred
from the
common container to a second container. In some embodiments, the contents are
then
repeatedly transferred from container to container so that a relatively
homogenous mixture of
flow enhancing additive and cementitious and/or non-cementitious materials is
achieved. In
preferred embodiments, the contents of the second container are transferred
back to the
common container, then back to the second container, and so forth, until the
material has
been transferred at least four times.
[0028] In some einbodiinents, after cementitious and/or non-cementitious
materials are dry-blended with a flow enhancing additive of the present
invention, the blend
may be stored in storage tanks without substantial deterioration of the flow
properties of the
cementitious and/or non-cementitious materials or the undesirable consequences
of the flow
enhancing additive freezing. In certain embodiments, after a period of storage
in a storage
tank, the blend may be conveyed from the storage tank by mechanical or
pneumatic means
CA 02680392 2009-09-09
WO 2008/113975 PCT/GB2008/000847
9
without unintentionally leaving a significant portion of the blend in the
storage tank. The
term "significant portion" is defined herein to mean a portion of the stored
bleiid that is above
15% of the total volume thereof.
[0029] It has also been discovered that after dry-blending a cementitious
and/or non-cementitious material with a flow enhancing additive of the present
invention and
placing the resulting blend in a storage tank, if the tank is closed to the
atmosphere and the
blend is aged in the closed storage tank for a time period in the range of
from about one half a
day to about four days, the particulate blend is more readily and easily
conveyed out of the
storage tank.
[0030] According to some embodiments of the methods of the present
invention, after a flow enhancing additive is blended with a cementitious
and/or non-
cementitious material, an amount of water sufficient to form a pumpable slurry
may be added
to the blend. In certain embodiments, the pumpable slurry may be placed in a
subterranean
formation. The pumpable slurry may be placed in the subterranean formation in
conjunction
with a subterranean cementing operation or another subterranean treatment. Any
means
known in the art for placing a slurry into a subterranean formation may be
suitable for use in
the present invention, including, but not limited to, pumping, injecting,
flowing, and
hydraj etting.
[0031] Some embodiments of the present invention comprise the steps of
providing a cementitious and/or non-cementitious material comprising a flow
enhancing
additive, wherein the flow enhancing additive further comprises a flow
inducing chemical
adsorbed onto a solid adsorbent particulate material, ethylene glycol, and
water; allowing the
cementitious or non-cementitious material to interact with a sufficient amount
of water to
form a pumpable slurry; and placing the cementitious and/or non-cementitious
material in a
subterranean formation.
[0032] To facilitate a better understanding of the present invention, the
following examples of certain aspects of some embodiments are given. In no way
should the
following exainples be read to limit, or define, the entire scope of the
invention.
EXAMPLE 1
[0033] To determine whether a flow enhancing additive comprising a flow
inducing chemical adsorbed onto a solid adsorbent material, ethylene glycol,
and water might
have a depressed freezing point compared to similar additives comprising only
a flow
inducing chemical adsorbed onto a solid adsorbent material, experimental
samples were
CA 02680392 2009-09-09
WO 2008/113975 PCT/GB2008/000847
prepared in 300 mL bottles, the bottles were secured with a lid, and stored in
a 10 F freezer
as follows: Sample 1, representing a control sample, contained 30 grams of EZ-
FLO
obtained from Halliburton Energy Services of Duncan, Oklalloma. The bottle was
placed in
the freezer overnight and froze into a solid, rock-like mass. Upon thawing,
the sample
regained its free-flowing properties. Sample 2 was prepared by placing 30
grams of EZ-FLO
(from the same batch used to prepared Sample 1), 5 grams of water, and 1.5
grams of
ethylene glycol in a bottle and hand shaking to evenly distribute the
materials. After one
night in the freezer, Sample 2 remained free flowing. Sample 2 was returned to
the freezer,
and after two more days (three total days of cold-storage), the flow
properties of Sainple 2
were visibly unchanged. To prepare Sample 3, 30 more grams of EZ-FLO were
added to the
three day-old Sample 2, and the materials were combined through hand shaking.
After 24
hours in the freezer, most of Sample 3 was still free flowing, but some
material stuck to the
sides of the container.
EXAMPLE Z
[0034] To explore whether flow enhancing additives comprising a flow
inducing chemical adsorbed onto a solid adsorbent material, ethylene glycol,
and water
would improve the flow properties of cementitious materials when the flow
enhancing
additives and cementitious materials were dry-blended together, a standard
pack set index
was created.
[0035] As shown in Table 1, Samples 1 and 3 contained only Portland cement
and no additives. Samples 2, 4, and 5 contained additive in an amount weighing
about .07%
of the weight of the cement. The cements used in the samples were Class G
Portland
cements purchased from the Norcem Cement Company of Norway and Dykerhoff AG of
Germany. The composition of the additives varied according to the sample. The
additive
that was used in Sample 2 was pure EZ-FLO product obtained from Halliburton
Energy
Services, Inc. of Duncan, Oklahoma. The additive that was used in Sample 4 was
prepared
by mixing 30 grams of EZ-FLO product with 6 grams of a 30% ethylene glycol
solution (i. e.,
30% ethylene glycol by weight of the water present in the ethylene glycol
solution). The
additive that was used in Sample 5 was prepared by mixing 30 grams of EZ-FLO
product
with 6 grams of a 50% ethylene glycol solution
[0036] The ability of the samples to resist packing was tested by a placing a
volume of each sample sufficient to achieve a packed thickness of
approximately 3/4 inch in
a 200 mL sealed flask. The cement blend was swirled in the flask until a level
cement
CA 02680392 2009-09-09
WO 2008/113975 PCT/GB2008/000847
11
surface was obtained. The flask containing the cement blend was then placed on
a Model J-1
A SYNTRON JOGGER vibrating machiiie and vibrated for a pre-determined period
at a set
voltage. After the vibration period, the flask containing the cement blend was
removed from
the vibrator and placed on a rotator that slowly rotated the flask in a
vertical plane. The flask
was continuously rotated for the number of counts required for the cement
blend in the flask
to show initial and then complete separation between the particles of the
blend. After the
cement blend decompacted, the flask containing the cement blend was shaken
vigorously and
the cement blend was re-swirled for 5 seconds whereupon the test was repeated.
This
procedure was repeated for a total of three or 4 tests, as indicated in Table
2, which shows the
results of each test. All tests were performed at room temperature.
Table 1
Make-up of Sample
Components of ethylene
Additive (Additive is glycol in
added to Cement in the Rotations
an amount of about ethylene Rotations until until
Sample .07% by weight of the glycol Initial Complete
No. Cement Cement) solution Rotations Separation Separation
I Class G - 25 seconds 24 26
Norcem - - at 28 32
57 Volts 27 30
2 Class G - 25 seconds 8 9
Norcem Pre-made EZ-FLO - at 6 8
57 Volts 8 10
3 Class G - 23 seconds 19 25
Norcem - - at 19 30
48 Volts 18 19
4 Class G - 23 seconds 10 14
Dykerhoff 30g Pre-made EZ-FLO at 7 9
6g ethylene glycol 30% 48 Volts 12 15
solution
13 16
Class G - 23 seconds 10 15
Dykerhoff 30g Pre-made EZ-FLO at 11 16
6g ethylene glycol 50% 48 Volts
solution 10 11
7 8
[0037] The same procedure was performed on samples containing additives
that did not contain pre-made EZ-FLO product. As seen in Table 2, Samples 6
and 9
contained only Class G cement. Samples 7, 8, 10 and 11 contained additive in
an amount
weighing about .07% by weight of the cement. These additives were prepared
"from
scratch," using glacial acetic acid, particulate silica, and either a 30% or
50% ethylene glycol
solution. The particulate silica used in the samples is available under the
tradenalne
"Sipernat-22TM" from Degussa DmbH of Germany. As shown in Table 2, these
components
CA 02680392 2009-09-09
WO 2008/113975 PCT/GB2008/000847
12
were hand-mixed to prepare the additives used in Sample 7 and Sample 8, and
blended
together in a blender to prepare the additives used in Sample 10 and Sample
11. The results
of each test are shown in Table 2.
Table 2
Make-up of Sample
%
Components of ethylene
Additive (Additive is glycol in
added to Cement in an the Rotations
amount of about.07% ethylene Rotations until until
Sample by weight of the glycol Initial Complete
No. Cement Cement) solution Rotations Separation Separation
6 Class G- 25 seconds 23 27
Norcem
- - at 22 37
57 Volts 25 29
7 Class G - Hand-mixed: 9 12
Norcem 15g glacial acetic acid 25 seconds 8 11
159 particulate silica 30% at
6g ethylene glycol 57 Volts 7 10
solution 7 9
8 Class G - Hand-mixed: 12 14
Dykerhoff 15g glacial acetic acid 25 seconds 6 9
15g particulate silica 50% at
6g ethylene glycol 57 Volts 4 6
solution 3 5
9 Class G - 25 seconds 25 29
Norcem at 24 31
57 Volts 21 32
Class G - Mixed in blender: 4 6
Dykerhoff l 5g glacial acetic acid 25 seconds 4 5
15g particulate silica 30% at 6 9
6g ethylene glycol 57 Volts
solution 3 7
11 Class G- 4 6
Dykerhoff Mixed in blender:
15g glacial acetic acid 25 seconds
15g particulate silica 50% at 4 7
6g ethylene glycol 57 Volts 3 6
solution
7 8
[0038] As can be seen from Table 1 and Table 2, all of the samples that
contained an additive, whether pure EZ-FLO, EZ-FLO plus ethylene glycol
solution, or a
from-scratch mixture of glacial acetic acid, particulate silica, and ethylene
glycol solution,
showed reduced packing compared to samples that did not contain an additive.
[0039] To determine whether an atomizer would be an effective means to
apply a mixture of flow inducing chemical, water, and ethylene glycol to a
particulate solid
adsorbent material, a pack set index was created as described above. Sample
12, serving as a
control sample, comprised only Class 0 cement. Sample 13 comprised Glass G
cement and
CA 02680392 2009-09-09
WO 2008/113975 PCT/GB2008/000847
13
.07% of pre-made EZ-FLO by weight of the cement. Sample 14 was prepared by
mixing 150
grams glacial acetic acid with 50 grams of water and 15 grams of ethylene
glycol (i.e., a 30%
ethylene glycol solution), and placing the mixture in an atomizer. The
atomizer was then use
to apply this mixture to 150 grams of "Sipernat-22TM" precipitated silica that
was
continuously stirred in a 2 quart blender jar at a rate of 3000 rpm. After all
of the acetic
acid/water/ethylene glycol mixture was applied to the precipitated silica to
create a flow
enhancing additive, the flow enhancing additive was added to Glass G cement in
an amount
of about .07% by weight of the cement. The pack set index that was created
using samples
12, 13, 14, and 15 is shown in Table 3. As can be seen, in some embodiments,
an atomizer
may be an effective means for introducing the liquid components of a flow
enhancing
additive to the solid components of the flow enhancing additive.
Table 3
Make-up of Sample
Components of
Additive (Additive is
added to Cement in an % ethylene Rotations Rotations
amount of about.07% glycol in the until until
Sample by weight of the ethylene glycol Initial Complete
No. Cement Cement) solution Rotations Separation Separation
25 seconds 27 29
Class G -
12 Dykerhoff 57 Volts 29 30
32 33
25 seconds 18 20
13 Class G- Pre-made EZ-FLO - at 18 21
Dykerhoff 57 Volts
16 17
150 silica 18 20
Class G- g particulate 25 seconds
14 Dykerhoff 150g glacial acetic acid 30% at 18 20
65g ethylene glycol 57 Volts
solution 16 18
[0040] To deternline whether an embodiment of a flow enhancing additive of
the present invention would also reduce packing in Class A cement, Samples 15
and 16 were
prepared and subjected to the pack set test described above. Sample 15
contained only Joppa
Class A cement from LaFarge North America. Sample 16 contained Class A Joppa
cement
and an additive in an amount weighing about .07% by weight of the cement. The
additive
was prepared by mixing 30 grams of pre-made EZ-FLO product with 6 grams of
ethylene
glycol solution. The ethylene glycol solution was comprised of water and 30%
ethylene
glycol by weight of the water. As can be seen from the test results summarized
in Table 4,
the additive was effective to decrease packing of the Joppa Class A cement.
CA 02680392 2009-09-09
WO 2008/113975 PCT/GB2008/000847
14
Table 4
Make-up of Sample
o~a
Components of ethylene
Additive (Additive is glycol in
added to Cement in the Rotations
an amount of about ethylene Rotations until until
Sample .07% by weight of glycol Initial Complete
No. Cement the Cement) solution Rotations Separation Separation
15 Class A - 25 seconds 23 25
Joppa - - at 27 29
57 Volts 17 19
16 Class A - 25 seconds 12 13
Joppa FLO 0 11
6g ethylene glycol 30% 57 Volts 12 14
solution 13 14
EXA.MPLE 3
[0041] As a qualitative study of the freezing point of certain flow enhancing
additives which comprise a flow inducing chemical adsorbed onto a solid
adsorbent material,
ethylene glycol, and water, various sample additives were prepared and stored
in a 20 F
freezer. In addition to testing the freezing point of the sample additives in
the absence of
cement, a pack set index was created for each additive as described in Example
2. The
samples were prepared as shown in Table 5, in duplicate.
CA 02680392 2009-09-09
WO 2008/113975 PCT/GB2008/000847
Table 5
Amount of particulate solid adsorbent material Amount of ethylene glycol %
Etliylene Glycol by weiglit of
combined with a flow-inducing chemical in a solution (granis) water in the
ethylene glycol
1:1 weight ratio (grams) solution
Control Sample (EZ-F30 LO) 0 0
Sample 1 (EZ-F30 LO) 6.5 30
Sample 2 (EZ-F30 LO) 3.25 30
Sample 3 (EZ-F30 LO) 1.625 30
Sample 4 (EZ-F30 LO) 6 50
Sample 5 (EZ-F30 LO) 3 50
1.5 50
Sample 6 (EZ-30 FLO)
Sample 7 30
(15g particulate silica+ 15 g acetic acid) 6.5 30
Sample 8 (15g particulate silica+ 15 g acetic acid) 5 50
[0042] All samples were placed in a sealed jar. At ambient room temperature,
all samples were free-flowing like a loose powder. When stored in the freezer
overnight, the
control sample froze into a solid, rock-like mass. The control sample was
allowed to come to
room temperature and was then returned to the freezer for two more days. The
control
sample re-froze as before. Samples 1-5, 7, and 8 (two replicates per sample)
all remained
free-flowing after being placed in the freezer overnight. After one night in
the freezer, the
samples were allowed to come to room temperature and then returned to the
freezer. At the
conclusion of two more days, the samples were still free-flowing. One
replicate of Sample 6
showed signs of partial freezing after both storage periods, i.e., irregular
clumps were
observed in the jar. The other replicate of Sample 6 never showed any signs of
freezing. It is
thought that the unusual results from the first replicate of Sample 6 may have
been due to an
incomplete mixing or uneven distribution of its component materials. The pack
set tests
performed on the samples showed that all of the sample mixtures were effective
to reduce the
tendency of cement to pack.
CA 02680392 2009-09-09
WO 2008/113975 PCT/GB2008/000847
16
EXAMPLE 4
[0043] To compare the gelation of a cement slurry comprising cement, water
and pure EZ-FLO additive to the gelation of a cement slurry comprising cement,
water, EZ-
FLO, and an ethylene glycol solution, two sample cement slurries were
prepared. Slurry 1
contained 700 grams of a standard cement, 325.9 grams of water, and 0.5 grams
of EZ-FLO.
Slurry 2 contained 700 grams of a standard cement, 325.9 grams of water, and
0.5 grams of a
mixture of EZ-FLO and ethylene glycol solution, wherein the mixture of EZ-FLO
and
ethylene glycol solution was prepared by combining 30 grams of EZ-FLO and 6
grams of a
solution of water and 30% ethylene glycol by weight of the water. In general,
the procedures
used to test the gelation properties of the samples conformed to the
procedures described in
the API publication entitled "Well Stimulation Thickening Time Test." The
slurries were
analyzed for at least 6 hours with a Model 7222 CHANDLER consistometer. Within
about
the first 10 minutes of the test, the temperature of the slurries was adjusted
to about 80 F and
the pressure was adjusted from an initial pressure of about 1000 psi to about
3000 psi. The
temperature and pressure were then kept relatively constant for the duration
of the test. Over
time, the viscosity of both slurries, as measured in Bearden units (Bc),
increased sharply.
Therefore, according to this embodiment, the presence of ethylene glycol in
Slurry 2 did not
prevent a desirable increase in the viscosity of the slurry over time.
[0044] Therefore, the present invention is well adapted to attain the ends and
advantages mentioned as well as those that are inherent therein. The
particular embodiments
disclosed above are illustrative only, as the present invention may be
modified and practiced
in different but equivalent manners apparent to those skilled in the art
having the benefit of
the teachings herein. Furthermore, no limitations are intended to the details
of construction or
design herein shown, other than as described in the claims below. It is
therefore evident that
the particular illustrative embodiments disclosed above may be altered or
modified and all
such variations are considered within the scope and spirit of the present
invention. In
particular, every range of values (of the form, "from about a to about b," or,
equivalently,
"from approximately a to b," or, equivalently, "from approximately a-b")
disclosed herein is
to be understood as referring to the power set (the set of all subsets) of the
respective range of
values, and set forth every range encompassed within the broader range of
values. Also, the
terms in the claims have their plain, ordinary meaning unless otherwise
explicitly and clearly
defined by the patentee.
