Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 02644991 2008-09-05
WO 2008/017414 PCT/EP2007/006815
Pumpable geopolymer formulation for oilfield
application
Field of the invention
[0001] The present invention broadly relates to well cementing. More
particularly the
invention relates to the use of geopolymers, to pumpable geopolymer
formulations and
the related methods of placing the geopolymer formulations in a well using
conventional
or unconventional cementing techniques.
Description of the Prior Art
[0002] Geopolymers are a novel class of materials that are formed by chemical
dissolution and subsequent recondensation of various aluminosilicate oxides
and silicates
to form an amorphous three-dimensional framework structure. Therefore, a
geopolymer
is a three-dimensional aluminosilicate mineral polymer. The term geopolymer
was
proposed and first used by J. Davidovits (Synthesis of new high-temperature
geo-
polymers for reinforced plastics/composites, SPE PACTEC' 79, Society of
Plastics
Engineers) in 1976 at the IUPAC International Symposium on Macromolecules held
in
Stockholm.
[0003] Geopolymers based on alumino-silicates are designated as poly(sialate),
which is an abbreviation for poly(silicon-oxo-aluminate) or (-Si-O-Al-O-)'j
(with n being
the degree of polymerization). The sialate network consists of Si04 and A104
tetrahedra
linked alternately by sharing all the oxygens, with A13+ and Si4+ in IV-fold
coordination
with oxygen. Positive ions (Na+, K+, Li+, Cat+...) must be present in the
framework
cavities to balance the negative charge of A13+ in IV-fold coordination.
[0004] The empirical formula of polysialates is: Mn {-(SiO2)Z AlO2}n, w H2O,
wherein M is a cation such as potassium, sodium or calcium, n is a degree of
polymerization and z is the atomic ratio Si/Al which may be 1, 2, 3 or more,
until 35 as
known today.
CONFIRMATION COPY
CA 02644991 2008-09-05
WO 2008/017414 PCT/EP2007/006815
[0005] The three-dimensional network (3D) geopolymers are summarized in the
table
I below.
Si/Al Designation Structure Abbreviations
ratio
1 Poly(sialate) Mn(-Si-O-Al-O-)n (M)-PS
2 Pol (sialate-siloxo Mn(-Si-O-Al-O-Si-O)n (M)-PSS
3 Poly(sialate-disiloxo) Mn(-Si-O-Al-O-Si-O-Si-O-)n (M)-PSDS
Table 1 : Geopolymers chemical designation (wherein M is a cation such as
potassium, sodium or
calcium, and n is a degree of polymerization).
[0006] The properties and application fields of geopolymers will depend
principally
on their chemical structure, and more particularly on the atomic ratio of
silicon versus
aluminum. Geopolymers have been investigated for use in a number of
applications,
including as cementing systems within the construction industry, as refractory
materials
and as encapsulants for hazardous and radioactive waste streams. Geopolymers
are also
referenced as rapid setting and hardening materials. They exhibit superior
hardness and
chemical stability.
[0007] Various prior art disclose the use of geopolymer compositions in the
construction industry. In particular US 4,509,985 discloses a mineral polymer
composition employed for the making of cast or molded products at room
temperatures,
or temperatures generally up to 120 C; US 4,859,367, US 5,349,118 and US
5,539,140
disclose a geopolymer for solidifying and storing waste material in order to
provide the
waste material with a high stability over a very long time, comparable to
certain
archeological materials, those waste materials can be dangerous or potentially
toxic for
human beings and the natural environment; or US5,356,579, US5,788,762,
US5,626,665,
US5,635,292 US5,637,412 and US5,788,762 disclose cementitious systems with
enhanced compressive strengths or low density for construction applications.
Patent
application W02005019130 is the first to highlight the problem of controlling
the setting
time of the geopolymer system in the construction industry. Effectively, as
the
geopolymers have a rapid set time, a retarder could be used to lengthen this
set time.
[0008] However none of the prior art has discussed geopolymers for application
in
the oilfield industry. And if W02005019130 has the merit to disclose a
specific type of
2
CA 02644991 2009-07-29
novel family of geopolymers with some retarding effects on the set time for
the construction
industry, no real control of the set time is proposed for all the other
geopolymer systems. In
addition further major technical challenges affect potential cementing systems
to be used in
the oilfield industry. These problems are, for example the control of the
thickening and
setting times for large temperature and density ranges for the geopolymer
slurry, the
mixability and also the pumpabilty of such slurry. Other properties have also
to be
considered, such as the compressive strength and permeability of the set
geopolymer
material. Therefore, it would be desirable to produce geopolymers solving
those problems
and having still good properties for oilfield applications.
to Summary of the invention
[0009] In accordance with one aspect of the present invention, there is
provided a
suspension comprising an aluminosilicate source; a carrier fluid; an activator
comprising a
metal silicate, a metal aluminate, an alkali activator, or a combination
thereof; wherein the
suspension is a pumpable composition in oilfield industry and the suspension
is settable
under well downhole conditions.
[0009a] In accordance with another aspect of the present invention, there is
provided a
suspension comprising an aluminosilicate source; a carrier fluid; an activator
comprising a
metal silicate of an alkali metal (M), an aluminate of said metal, an alkali
activator, or a
combination thereof; and a retarder for retarding the thickening and/or the
setting times of
the suspension and/or an accelerator for accelerating the thickening and/or
the setting times
of the suspension, wherein the oxide molar ratio M2O/SiO2 is greater than
0.20.
[0009b] In accordance with another aspect of the present invention, there is
provided a
method to control the setting time and/or the thickening time of a
geopolymeric suspension
for oilfield industry, comprising the step of providing said suspension within
a carrier fluid
by adding a retarder and/or an accelerator; an aluminosilicate source; an
activator
comprising a metal silicate, a metal aluminate, an alkali activator, or a
combination thereof.
[0009c] In accordance with another aspect of the present invention, there is
provided a
method to control the density of a geopolymer suspension for oilfield
industry, comprising
the step of providing said suspension within a carrier fluid by adding
lightweight particles
3
CA 02644991 2009-07-29
and/or heavy particles; an aluminosilicate source; an activator comprising a
metal silicate, a
metal aluminate, an alkali activator, or a combination thereof.
[0009d] In accordance with another aspect of the present invention, there is
provided a
method to control the density of a geopolymer suspension for oilfield
industry, comprising
the step of providing said suspension within a carrier fluid by mixing an
aluminosilicate
source and an activator wherein said activator comprises a metal silicate, a
metal aluminate,
an alkali activator, or a combination thereof; and foaming said suspension.
[0009e] In accordance with another aspect of the present invention, there is
provided a
method to place a geopolymeric composition in a borehole in a formation
comprising the
step of providing a suspension within a carrier fluid by mixing an
aluminosilicate source
and an activator, wherein said activator comprises a metal silicate, a metal
aluminate, an
alkali activator, or a combination thereof, pumping said suspension into the
borehole, and
allowing said suspension to set under wellbore downhole conditions and thereby
form the
geopolymeric composition.
[0009f] In one embodiment the invention discloses a suspension comprising an
aluminosilicate source, a carrier fluid, an activator taken from the list
constituted by: a metal
silicate, a metal aluminate, an alkali activator or a combination thereof, and
wherein the
suspension is a pumpable composition in the oilfield industry and the
suspension is able to
set under well downhole conditions. All the three components do not need
necessarily to be
added separately: for example the activator can be already within a carrier
fluid. So, the
aluminosilicate source can be in the form of a solid component; the metal
silicate can be in
the form of a solid or of a mix of metal silicate within a carrier fluid; the
activator can be in
the form of a solid or of a mix of activator within a carrier fluid.
Importance is to have a
carrier fluid to make suspension if aluminosilicate source, metal silicate and
activator are all
in solid state. If aluminosilicate source, metal silicates are in solid state
and activator is in
liquid state, activator is considered to already have a carrier fluid within.
Further, as it is
understood, unicity of the carrier fluid is not required, two or more carrier
fluids can be used.
The geopolymeric composition has such rheological properties that the
suspension of said
geopolymeric composition has a good pumpability and stability. A pumpable
composition
in the oilfield industry has a rheology lesser than or equal to 300 cP,
preferably in other
3a
CA 02644991 2009-07-29
embodiment lesser than or equal to 250 cP, more preferably in another
embodiment lesser
than or equal to 200 cP. Further, the suspension made is a stable suspension.
The
geopolymeric
3b
CA 02644991 2008-09-05
WO 2008/017414 PCT/EP2007/006815
composition is mixable and pumpable; therefore applications in the oilfield
industry are
possible.
[0010] To control the setting time of the geopolymeric composition the alkali
activator is chosen with a given pH, and/or a retarder is added and/or an
accelerator is
added to the suspension of said geopolymeric composition. The alkali activator
can be
generally an alkali metal hydroxide, more preferably a sodium or potassium
hydroxide; it
can be also a carbonate material. The retarder is selected from the group
constituted of
boron containing compound, lignosulfate, sodium gluconate, sodium
glucoheptonate,
tartaric acid and phosphorus containing compounds. Preferably, the retarder is
an
anhydrous or hydrated alkali metal borate or a pure oxide of boron. More
preferably, the
retarder is a sodium pentaborate decahydrate, boric acid, or borax. The
accelerator is an
alkali metal preferably: a lithium or potassium containing compound.
Preferably the
accelerator is a salt of lithium. More preferably, the accelerator is lithium
chloride. The
control of the setting time is here efficient from 20 C to 200 C. Sodium
pentaborate
decahydrate and borax are able to control setting time from 20 C, preferably
from 25 C
to 150 C.
[0011] To control the setting time of the geopolymer composition, the type of
alumino silicate is specifically chosen depending of the temperature
application.
[0012] To control the density of the geopolymeric composition, a lightweight
particle
and/or a heavyweight material can be added. The lightweight particles also
called fillers
are selected from the group constituted of. cenospheres, sodium-calcium-
borosilicate
glass, and silica-alumina microspheres. The heavy particles also called the
weighting
agents are typically selected from the group constituted of: manganese
tetraoxide, iron
oxide (hematite), barium sulfate (barite), silica and iron/titanium oxide
(ilmenite). The
geopolymeric compositions can also be foamed by foaming the suspension of said
geopolymeric composition with a gas as for example air, nitrogen or carbon
dioxide. The
geopolymeric composition can further comprise a gas generating additive which
will
introduce the gas phase in the suspension. Preferably, the density of the
suspension of
said geopolymeric slurry compositions varies between I gram per cubic
centimeter and
4
CA 02644991 2008-09-05
WO 2008/017414 PCT/EP2007/006815
2.5 grams per cubic centimeter, more preferably between 1.2 grams per cubic
centimeter
and 1.8 grams per cubic centimeter.
[0013] In a second embodiment, the suspension of said geopolymeric composition
can further comprise a mixture of two or more aluminosilicate source. In a
further other
embodiment, the suspension of said the geopolymeric composition can comprise a
second
binder component which may be a conventional cementing material such as
Portland
cement, micro-cement or silica fume.
[0014] In a third embodiment, the suspension of said geopolymeric composition
can
comprise a gas phase so the gas phase or part of the gas phase remains in the
geopolymeric composition. For example, the gas phase can be a water-immiscible
dispersed nitrogen phase.
[0015] In a fourth embodiment, the suspension of said geopolymeric composition
can
comprise a water-immiscible phase. For example, this can be a water-immiscible
dispersed oil-based phase.
[0016] In a fifth embodiment, the geopolymeric composition further comprises
an
additive selected from the group constituted of: an activator, an antifoam, a
defoamer,
silica, a fluid loss control additive, a flow enhancing agent, a dispersant, a
rheology
modifier, a foaming agent, a surfactant and an anti-settling additive.
[0017] The geopolymeric composition according to the invention are preferably
poly(sialate), poly(sialate-siloxo) or poly(sialate-disiloxo). More
preferably, the
geopolymeric composition are poly(sialate-siloxo) components and therefore the
silicon
to aluminum atomic ratio is substantially equal to two, between 1.8 and 2.8.
[0018] In another aspect of the invention is a suspension comprising an
aluminosilicate source, a carrier fluid, an activator taken from the list
constituted by: a
metal silicate, a metal aluminate, an alkali activator, or a combination
thereof, and a
retarder able to retard the thickening and/or the setting times of the
suspension and/or an
accelerator able to accelerate the thickening and/or the setting times of the
suspension,
5
CA 02644991 2008-09-05
WO 2008/017414 PCT/EP2007/006815
wherein the metal is an alkali metal and the oxide molar ratio M20/SiO2 is
greater than
0.20 wherein M is the metal..
[0019] When the retarder is used, it is preferably a boron containing compound
and
the suspension of said geopolymeric composition has preferably an oxide molar
ratio
B2O3/1-I2O of less than 0.03.
[0020] When the accelerator is used, it is preferably a lithium or potassium
containing compound. The suspension of said geopolymeric composition has
preferably
an oxide molar ratio Li20/H20 of less than 0.2. More preferably, the
geopolymeric slurry
composition has an oxide molar ratio Li20/H20 of less than or equal to 0.1.
[0021] The geopolymeric composition according to the invention uses
aluminosilicate source which is selected from the group constituted of ASTM
type C fly
ash, ASTM type F fly ash, ground blast furnace slag, calcined clays, partially
calcined
clays (such as metakaolin), aluminium-containing silica fume, natural
aluminosilicate,
synthetic aluminosilicate glass powder, zeolite, scoria, allophone, bentonite
and pumice.
Preferably, the geopolymeric composition is made with metakaolin, kaolin,
ground
granulated blast furnace slag and/or fly ash.
[0022] The geopolymeric composition according to the invention uses a metal
silicate, with the metal selected from the group constituted of lithium,
sodium, potassium,
rubidium and cesium. Preferably, the metal is sodium or potassium. In another
embodiment, the metal silicates can be replaced by ammonium silicates. The
metal
silicate in another embodiment can be encapsulated.
[0023] The geopolymeric composition according to the invention uses for the
alkali
activator, for example an alkali metal hydroxide. Preferably, the alkali metal
hydroxide is
sodium or potassium hydroxide. The alkali activator and/or the metal silicate
may be
encapsulated. Alkali carbonates can also be used as alkali activator. Also,
the alkali
activator in another embodiment can be encapsulated.
[0024] The geopolymeric composition according to the invention uses for the
carrier
fluid preferably an aqueous solution such as fresh water.
6
CA 02644991 2008-09-05
WO 2008/017414 PCT/EP2007/006815
[0025] In another aspect of the invention a method to control the setting time
of a
geopolymeric suspension for oilfield applications is disclosed. The method
comprises the
step of providing said suspension within a carrier fluid by adding: (i) a
retarder and/or an
accelerator; (ii) an aluminosilicate source; (iii) an activator taken in the
list constituted
by: a metal silicate, a metal aluminate, an alkali activator, or a combination
thereof. The
previous steps can be realized in another order. The geopolymer compositions
of the
invention prepared according to the method have controllable setting times at
temperatures ranging from 20 C to at least 200 C. The geopolymeric composition
used is
the same as disclosed above. And, the alkali activator is selected from the
group
constituted of. sodium hydroxide and potassium hydroxide; the retarder is
selected from
the group constituted of boron containing compound, lignosulfate, sodium
gluconate,
sodium glucoheptonate, tartaric acid and phosphorus containing compounds.
[0026] To control the thickening and/or the setting times of the geopolymeric
composition, the nature and/or the pH and/or the concentration of the
activator and/or the
concentration of the metal silicate is changed. By increasing the
concentration of the
activator, the setting time is shortened and by changing the nature and/or pH,
different
setting times are obtained. To control the thickening time of the geopolymeric
composition the nature and/or the concentration of the retarder is changed. By
increasing
the concentration of the retarder, the setting time is lengthened and by
changing the
nature, different setting times are obtained. In the same way, to control the
setting time of
the geopolymeric composition the nature and/or the concentration of the
accelerator is
changed. By increasing the concentration, the setting time is shortened and by
changing
the nature, different setting times are obtained. As it can be seen, three
solutions exist to
control the setting time, use of a special activator, use of a retarder, or
use of an
accelerator. The three solutions can be used separately or in combination.
Sometimes, the
use of a special activator does not give sufficiently long setting time and
the use of a
retarder may be preferred. Similarly the use of a special activator may not
give
sufficiently short setting time and the use of an accelerator would be
preferred.
[0027] In another aspect of the invention a method to control the density of a
suspension for oilfield industry is disclosed. The method comprises the step
of providing
7
CA 02644991 2008-09-05
WO 2008/017414 PCT/EP2007/006815
said suspension within a carrier fluid by adding: (i) lightweight particles
and/or heavy
particles; (ii) an aluminosilicate source; (iii) an alkali activator taken in
the list
constituted by: a metal silicate, a metal aluminate, an alkali activator, or a
combination
thereof. The previous steps can be realized in another order. Still, in
another aspect of the
invention the method further comprises the step of adding a retarder and/or an
accelerator
to the suspension. Still, in another aspect of the invention the method
further comprises
the step of foaming the suspension of said geopolymeric composition.
[0028] In another aspect of the invention a method to control the density of a
suspension for oilfield industry is disclosed, the method comprises the step
of. (i)
providing said suspension within a carrier fluid by mixing an aluminosilicate
source, a
metal silicate and an activator taken in the list constituted by: a metal
silicate, a metal
aluminate, an alkali activator, or a combination thereof in a carrier fluid,
(ii) foaming the
suspension of said geopolymeric composition. Still, in another aspect of the
invention the
method further comprises the step of adding a retarder and/or an accelerator
to the
suspension.
[0029] The method to control the density of geopolymer compositions of the
invention applies for density range varying between I gram per cubic
centimeter and 2
grams per cubic centimeter, but could also be applied to density range varying
between
0.8 gram per cubic centimeter and 2.5 grams per cubic centimeter.
[0030] In another aspect of the invention a method to place a geopolymeric
composition in a borehole and isolate subterranean formations is disclosed,
the method
comprises the step of. (i) providing a suspension as described above (ii)
pumping said
suspension into the borehole, and (iii) allowing said suspension to set under
wellbore
downhole conditions and thereby form the geopolymeric composition.
[0031] In another embodiment, the step of providing a suspension of said
geopolymeric composition further comprises adding a retarder and/or an
accelerator
and/or an activator. Effectively, it can be useful to lengthen the set of the
geopolymeric
composition by adding a retarder as seen above and/or it can be useful to
accelerate the
set of the geopolymeric composition by adding an accelerator as seen above.
8
CA 02644991 2008-09-05
WO 2008/017414 PCT/EP2007/006815
[0032] Still, in another embodiment, the method comprises the step of
activating in
situ the suspension of said geopolymeric composition. Effectively, the method
also
applies if activation has to be realized downhole in the well, the activation
does not
necessarily refer to the alkali activator. Effectively, in a first embodiment
the activation
refers to activation via the alkali activator, the alkali activator is
encapsulated as
described previously or is released with a downhole device. In a second
embodiment, the
activation refers to any type of activation when various additives that need
activation are
used, as for example activation can be physical (by heat, UV radiation or
other
radiations); the activation can be made also with chemical components
encapsulated and
released at a predefined time or event. The capsule can be self destructed as
previously
explained or can be destroyed with help of stress and/or sonic perturbation.
[0033] In the first embodiment, the geopolymeric composition is retarded with
a
sufficiently long setting time so an activation has to be done to provoke the
set of
geopolymeric composition. The activation is made here by the release of an
activator.
This release is realized downhole, in situ, by adding the activator directly
to the
suspension of said geopolymeric composition and/or if the activator is
encapsulated in the
suspension of said geopolymeric composition by break of the capsules.
[0034] Still, in another embodiment, the method comprises the step of
activating the
suspension of said geopolymeric composition just before use. For example, an
inactivated
suspension of geopolymer composition is made so that said suspension is stable
for a
long time. Said composition is storable, transportable and accessorily
perishable after a
period varying between one day and some months, preferably some days and three
months. The storable suspension is taken to rig site in liquid form and is
activated before
pumping or downhole in situ as explained previously.
[0035] Preferably, the step of pumping the suspension of said geopolymeric
composition is made with conventional well cementing equipment, familiar to
those
skilled in the art. The method applies as a primary cementing technique for
cementing
wells where the geopolymeric composition is pumped down a pipe until the shoe
where it
then flows up the annular space between the casing/liner and the borehole. A
reverse
9
CA 02644991 2008-09-05
WO 2008/017414 PCT/EP2007/006815
circulation cementing technique can also be used for placing the geopolymer
suspension
at the desired depth in the borehole.
[0036] Further, the pumping and placement of geopolymer suspension below
surface
encompasses several other conventional cementing techniques such as the
grouting of
platform piles, skirts or the like, the squeeze operation for repair or
plugging of an
undesired leak, perforation, formation or the like, and the setting of a
geopolymer
composition plug for any purpose of a cement plug.
[0037] The methods apply also to the placement of the geopolymeric composition
to
squeeze a zone of the borehole. The methods can apply for water well,
geothermal well,
steam injection well, Toe to Heel Air Injection well or acid gas well. As such
the
composition can withstand temperature above 250 C, even above 450 C and 550 C.
Brief description of the drawing
[0038] Further embodiments of the present invention can be understood with the
appended drawings:
= Figure 1 shows the impact of temperature on the thickening time of
geopolymer
formulations.
= Figure 2 shows the impact of accelerator addition on the thickening time of
geopolymer formulations.
Detailed description
[0039] According to the invention, the geopolymer formulations involve the use
of an
aluminosilicate source, a metal silicate and an alkali activator in a carrier
fluid at near-
ambient temperature. The carrier fluid is preferably a fresh water solution.
As it has been
said previously, all the four components do not need necessarily to be added
separately:
for example the alkali activator can be already within water. So, the
aluminosilicate
source can be in the form of a solid component; the metal silicate can be in
the form of a
CA 02644991 2008-09-05
WO 2008/017414 PCT/EP2007/006815
solid or of an aqueous solution of metal silicate; the alkali activator can be
in the form of
a solid or of an aqueous solution of alkali activator.
[0040] Formation of the geopolymer concrete involves an aluminosilicate
source.
Examples of aluminosilicate source from which geopolymers may be formed
include
ASTM type C fly ash, ASTM type F fly ash, ground blast furnace slag, calcined
clays,
partially calcined clays (such as metakaolin),, aluminium-containing silica
fume, natural
aluminosilicate, synthetic aluminosilicate glass powder, zeolite, scoria,
allophone,
bentonite and pumice. These materials contain a significant proportion of
amorphous
aluminosilicate phase, which reacts in strong alkali solutions. The preferred
aluminosilicates are fly ash, metakaolin, kaolin and blast furnace slag.
Mixtures of two or
more aluminosilicate sources may also be used if desired. In another
embodiment, the
aluminosilicate component comprises a first aluminosilicate binder and
optionally one or
more secondary binder components which may be chosen in the list: ground
granulated
blast furnace slag, Portland cement, kaolin, metakaolin or silica fume.
[0041] Formation of the geopolymer material could involve also, an alkali
activator.
The alkali activator is generally an alkali metal hydroxide. Alkali metal
hydroxides are
generally preferred as sodium and potassium hydroxide. The metal hydroxide may
be in
the form of a solid or an aqueous mixture. Also, the alkali activator in
another
embodiment can be encapsulated. The alkali activator when in solid and/or
liquid state
can be trapped in a capsule that will break when subject for example, to
stress on the
capsule, to radiation on the capsule. Also, the alkali activator when in solid
and/or liquid
state can be trapped in a capsule that will naturally destroy due to the fact
that for
example, the capsule is made with biodegradable and/or self destructive
material. Also,
the alkali activator when in liquid state can be adsorbed onto a porous
material and will
be released after a certain time or due to a predefined event.
[0042] Formation of the geopolymer material could involve also, a metal
silicate or
aluminate or a combination of different metal silicates or aluminate. The
metal silicate is
generally an alkali metal silicate. Alkali metal silicates, particularly
sodium silicate or
potassium silicate, are preferred. Sodium silicates with a molar ratio of
Si02/Na2O equal
11
CA 02644991 2008-09-05
WO 2008/017414 PCT/EP2007/006815
to or less than 3.2 are preferred. Potassium silicates with a molar ratio of
Si02/K2O equal
to or less than 3.2 are preferred. Also, the metal silicate in another
embodiment can be
encapsulated.
[0043] The method of the invention is applicable to the oilfield, preferably
in
completion of the well bore of oil or gas wells. To be used in oilfield
application, a
pumpable geopolymer formulation is formed where the components are mixed with
a
carrier fluid. Various additives can be added to the suspension and the
suspension is then
pumped into the well bore. The suspension is then allowed to set up in the
well to provide
zonal isolation in the well bore.
Method of placement of the geopolymer
[0044] A typical property of geopolymer systems is their ability to set
without delay
after mixing. However for oilfield applications, mixable and pumpable
geopolymer
suspension is needed. For this reason, a way to retard the thickening of the
geopolymer
suspension or a way to control thickening times of the geopolymer is required.
[0045] A large family of retarders allowing delay in the set of the geopolymer
has
been found. In table 2, the results of thickening time tests performed as per
ISO 10426-2
Recommended Practice in a High Pressure High Temperature (HPHT) consistometer
are
reported. Such tests are performed to simulate the placement from surface to
downhole of
cement suspensions, at a defined Bottom Hole Circulating Temperature (BHCT).
To
realize such tests, a temperature heatup schedule is followed in order to
mimic placement
in a real well. For the tests performed at 57 C, the temperature is reached in
41 minutes
and the final pressure is 33.8 MPa (4900 psi). For the tests performed at 85
C, the
temperature is reached in 58 minutes and the final pressure is 55.1 MPa (8000
psi). For
the tests performed at 110 C, the temperature is reached in 74 minutes and the
final
pressure is 75.9 MPa (11000 psi).
12
CA 02644991 2008-09-05
WO 2008/017414 PCT/EP2007/006815
Temperature ( C) 57 85 110
Sam le A2 A2_ I B 2 C2 D2
Retarder %bwob (by weight Thickening time:
of blend):
None 0 6:25 0:53 0:37 5:45 1:40
Na2B 10016 ,10H20 0.65 6:30 3:00
1.3 23:52 6:08
1.6 7:30
1.8 10:39 9:51
2 13:05
2.6 28:23
H3B03 1.9 20:53
Phosphonate/sodium 1.2 7:00
pentaborate
Phosphonate/phosphate 6.4 > 15:00
salt
Lignosulfonate 1.51 3:12
Table 2 : Examples of IS010426-2 thickening time measured with HPHT
consistometer (hours:min)
obtained with different retarders at different temperature.
^ Sample A2 is made by dissolving the retarder amount in 358 g of water,
adding
the blend comprising 314 g of metakaolin and 227 g of sodium disilicate in the
solution under mixing, adding 17.2 g of sodium hydroxide under ISO 1026-2
mixing, pouring the suspension in HPHT cell. Sample A2 is then tested by
measuring the thickening time with the HPHT consistometer.
^ Sample B2 is made by dissolving the retarder amount in 265 g of water,
adding
the blend comprising 232 g of metakaolin, 168 g of sodium disilicate and 414 g
of
silica particles as filler in the solution under mixing, adding 13 g of sodium
hydroxide under ISO 10426-2 mixing, pouring the suspension in HPHT cell.
Sample B2 is then tested by measuring the thickening time with the HPHT
consistometer.
^ Sample C2 is made by dissolving the retarder amount in 422 g of sodium
hydroxide solution, adding the blend comprising 440 g of type F fly ash and 88
g
of sodium disilicate in the solution under mixing following ISO 10426-2
mixing,
13
CA 02644991 2008-09-05
WO 2008/017414 PCT/EP2007/006815
pouring the suspension in HPHT cell. Sample C2 is then tested by measuring the
thickening time with the HPHT consistometer.
^ Sample D2 is made by dissolving the retarder amount in 374 mL of water,
adding
the blend comprising 411 g of type F fly ash and 82 g of sodium disilicate
under
mixing at 4000 rpm, adding 75 g of sodium hydroxide under ISO 10426-2
mixing, pouring the suspension in HPHT cell. Sample D2 is then tested by
measuring the thickening time with the HPHT consistometer.
[0046] The retardation of geopolymeric formulations can be and is controlled
at
different BHCT by using either boron containing compounds as for example
sodium
pentaborate decahydrate, boric acid, borax, or lignosulphonate, or phosphorus
containing
compounds, or a mixture of them. Retardation of geopolymeric formulations will
be
sensitive to boron valence for boron containing compounds or phosphate valence
for
phosphorus containing compounds and/or to retarder concentration.
[0047] In table 3, the results obtained with Vicat apparatus with two boron-
based
retarders are presented. Vicat apparatus allows to measure when the setting of
the
material starts (IST) and ends (FST). It is based on the measurements of the
penetration
of a needle in a soft material. This apparatus is often used to realize pre-
study at ambient
temperature and atmospheric pressure.
Sample A3 B3
No additive 1:45 12:00
Na2B 10016 10H20
2.6 %bwob 3:00 -
5.2 %bwob 4:10 >500:00
Borax
4.2 %bwob 3:20 -
Table 3: Examples of initial setting time (hours:min) obtained with different
retarders with Vicat
apparatus at ambient temperature and atmospheric pressure.
^ Sample A3 is made by dissolving the retarder amount in 139 g of sodium
hydroxide solution, adding the blend comprising 105 g of metakaolin, 48 g of
sodium metasilicate and 17 g of silica particles as filler in the solution
under
14
CA 02644991 2008-09-05
WO 2008/017414 PCT/EP2007/006815
mixing. Sample A3 is then tested by pouring the suspension in a Vicat cell to
measure setting time at 25 C.
^ Sample B3 is made by dissolving the retarder amount in 358 g of water,
adding
the blend comprising 314 g of metakaolin and 227 g of sodium disilicate in the
solution under mixing, adding 17.2 g of sodium hydroxide under ISO 10426-2
mixing. Sample B3 is then tested by pouring the suspension in a Vicat cell to
measure setting time at 25 C.
[0048] Retardation of geopolymeric formulations is sensitive to temperature.
However, two boron-based retarders (sodium pentaborate decahydrate and borax)
are
able to strongly retard different types of geopolymer suspensions even at 25
C.
[0049] Figure 1 illustrates the impact of temperature on the thickening time
for a
geopolymer composition made by adding a blend comprising 411 g of type F fly
ash and
82 g of sodium disilicate in 374 mL of water under mixing (retarder being
predissolved in
this water) and by adding 36.5 g of sodium hydroxide under ISO 10426-2 mixing.
This
way, retarders are efficient even at high temperature to control geopolymer
suspension
thickening time.
[0050] Control of the thickening time can also be realized by other means. As
an
example the nature of the alkali activator and its pH have an impact on the
thickening
time. Table 4 illustrates the influence of the alkali activator on the
thickening time of
geopolymeric suspensions. It demonstrates the ability to select the alkali
activator source
according to the downhole conditions.
Sample A4 B4
100 Bc 0:53 >31:00
Table 4: Examples of ISO 10426-2 thickening time measured with HPHT
consistometer (hours:min)
with different alkali activators measured at 85 C.
^ Sample A4 is made by adding the blend comprising 314 g of metakaolin and
227 g of sodium disilicate in 358 g of water under mixing, adding 17.2 g of
sodium hydroxide under IS010426-2 mixing, pouring the suspension in HPHT
CA 02644991 2008-09-05
WO 2008/017414 PCT/EP2007/006815
cell. Sample A4 is then tested by measuring the thickening time with a HPHT
consistometer.
^ Sample B4 is made by adding the blend comprising 314 g of metakaolin and
227 g of sodium disilicate in 357 g of water under mixing, adding 23.4 g of
sodium bicarbonate under ISO 10426-2 mixing, pouring the suspension in HPHT
cell. Sample A4 is then tested by measuring the thickening time with a HPHT
consistometer.
[0051] Control of the thickening and setting times by these methods of
retardation
can also be efficiently done with geopolymer having different silicon versus
aluminum
ratio.
[0052] Furthermore, depending on properties of the geopolymer, it can be
suitable to
accelerate thickening of the suspension. Table 5 illustrates the accelerating
effect of
lithium compounds on the thickening time of geopolymeric suspensions at
temperature of
85 C. It demonstrates the ability of using lithium salts to control the
thickening time of
geopolymer suspensions.
Sample AS B5
No additive 22:57 5:21
LiC1
3.5 %bwob 9:07 -
7 %bwob 4:07
LiOH, H2O
2 %bwob - 3:19
Table 5: Examples of ISO 10426-2 thickening time measured with HPHT
consistometer (hours:min)
obtained with typ eF fly ashes and accelerators.
^ Sample AS is made by adding the blend comprising 480 g of superfine typer F
fly
ash and 96 g of sodium disilicate in 406 g of the sodium hydroxide solution
containing an accelerator following ISO 10426-2 mixing, pouring the suspension
in HPHT cell. Sample AS is then tested by measuring the thickening time with a
HPHT consistometer.
16
CA 02644991 2008-09-05
WO 2008/017414 PCT/EP2007/006815
^ Sample B5 is made by adding the blend comprising 442 g of standard type F
fly
ash and 88 g of sodium disilicate in 423 g of the sodium hydroxide solution
containing an accelerator following ISO 10426-2 mixing, pouring the suspension
in HPHT cell. Sample B5 is is then tested by measuring the thickening time
with a
HPHT consistometer.
[0053] Figure 2 illustrates the accelerating effect of lithium compounds on
the
thickening time for a geopolymer composition made by adding the blend
comprising 480
g of superfine type F fly ash and 96 g of sodium disilicate in 406 g of the
sodium
hydroxide solution containing the accelerator following ISO 10426-2 mixing.
The
thickening time versus time of the suspension is then measured at temperature
of 85 C.
This way, accelerators such as lithium salts are shown to efficiently decrease
the
thickening time of geopolymer suspensions. The degree of acceleration of
geopolymeric
formulations is sensitive to accelerator type and/or concentration.
[0054] Depending on the properties of the geopolymer and on properties of the
well,
a real control of the thickening time of the suspension can be established. To
increase the
thickening time, nature of the retarder used can be changed, concentration of
the retarder
can be increased, nature of the alkali activator used can be changed, and
nature of the
aluminosilicate used can be changed.
[0055] Further, when use in oilfield application is sought, the geopolymer
suspension
has to be pumpable. Table 6 hereunder illustrates the rheological properties
of
geopolymer suspensions measured at a bottom hole circulating temperature
(BHCT) of
60 C. Rheological values demonstrate the pumpability and the stability of
geopolymeric
suspensions for application in the oilfield industry.
Sample A6 B6 C6
PV/TIT after mixing 49/10 62/4 105/7
ISO 10426-2 PV/TY at BHCT 48/7 53/2 85/7
cP/lbf/ 100ft2
ISO 10426-2 free fluid (mL) 0 0 0
Table 6: ISO 10426-2 Rheological and stability measurements obtained with
different examples.
17
CA 02644991 2008-09-05
WO 2008/017414 PCT/EP2007/006815
^ Sample A6 is made by adding the blend comprising 411 g of type F fly ash and
82 g of sodium disilicate in 374 mL of water under mixing, adding 75 g of
sodium
hydroxide under mixing. Sample A6 is then tested by measuring the rheological
properties of the suspension after mixing and after conditioning at 60 C
according
to the ISO 1026-2 standard procedure.
^ Sample B6 is made by dissolving the 0.65 %bwob of sodiumpentaborate
decahydrate in 422 g of sodium hydroxide solution, adding the blend comprising
440 g of type F fly ash and 88 g of sodium disilicate in the solution under
ISO
10426-2 mixing, adding 36.5 g of sodium hydroxide under mixing. Sample B6 is
then tested by measuring the rheological properties of the geopolymer
suspension
after mixing and after conditioning at 60 C according to the ISO 10426-2
standard procedure.
^ Sample C6 is made by adding the blend comprising 480 g of type F fly ash and
96 g of sodium disilicate in 406 g of the sodium hydroxide solution following
ISO
10426-2 mixing conditions. Sample C6 is then tested by measuring the
rheological properties of the suspension after mixing and after conditioning
at
60 C according to the ISO 1-0426-2 standard procedure.
[0056] Table 7 shows the difference of setting time according to the
conditions of
setting. The geopolymer formulation will set more rapidly in static than in
dynamic
conditions. Also normally, the geopolymer suspension should set rapidly after
placement.
Sample A7 B7
Additive None 2 %bwob LiOH, H2O
TT Test
Pressure of 8000 psi / dynamic 5:45 3:19
Vicat test (samples oven cured) 2:30 1:50
Atmospheric pressure / static
Table 7: Example comparing dynamic and static setting times (hours:min) at 85
C.
18
CA 02644991 2008-09-05
WO 2008/017414 PCT/EP2007/006815
^ Sample A7 is made by adding the blend comprising 440 g of type F fly ash and
88 g of sodium disilicate in 422 g of the water under mixing following ISO
10426-2 mixing, pouring the suspension in HPHT cell or the Vicat cell..
^ Sample B7 is made by adding the blend comprising 442 g of standard type F
fly
ash and 88 g of sodium disilicate in 424 g of the sodium hydroxide solution
containing 2 %bwob LiOH, H2O following ISO 10426-2 mixing, pouring the
suspension in HPHT consistometer or in the Vicat cell.
[0057] Also, when use in oilfield application is sought, the geopolymer
suspension
has to have a large range of densities. As presented in table 8, the tested
geopolymer
formulations propose a density range between 1.45 g/cm3 [ 12.1 lbm/gal] up to
1.84 g/cm3
[15.41bm/gal] either in reducing the water content, or in adding fillers.
Sample A8 B8
Suspension density g/cm 1.84 1.44
(lbm/ al) (15.4) (12.06)
Table 8: Examples of suspension density obtained with some geopolymeric
formulations.
^ Sample A8 is made by dissolving the retarder amount in 265 g of water,
adding
the blend comprising 232 g of metakaolin, 168 g of sodium disilicate and 414 g
of
silica particles as filler in the solution under mixing, adding 13 g of sodium
hydroxide under ISO 10426-2 mixing.
^ Sample B8 is made by dissolving the retarder amount in 139 g of sodium
hydroxide solution, adding the blend comprising 105 g of metakaolin, 48 g of
sodium metasilicate and 17 g of silica particles as filler in the solution
under
mixing.
[0058] Further, to broaden the density range, either lightweight particles are
added to
reach lower densities or heavy particles to reach higher densities. The
lightweight
particles typically have density of less than 2 g/cm3, and generally less than
1.3g/cm3. By
way of example, it is possible to use hollow microspheres, in particular of
silico-
aluminate, known as cenospheres, a residue that is obtained from burning coal
and having
a mean diameter of about 150 micrometers. It is also possible to use synthetic
materials
19
CA 02644991 2009-07-29
such as hollow glass bubbles, and .more particularly preferred are bubbles of
sodium-
calcium-borosilicate glass presenting high compression strength or indeed
microspheres of a
ceramic, e.g. of the silica-alumina type. The lightweight particles can also
be particles of a
plastics material such as beads of polypropylene. The heavy particles
typically have density
of more than 2 g/cm,, and generally more than 3 g/cm,. By way of example, it
is possible to
use hematite, barite, ilmenite, silica and also manganese tetroxide
commercially available
under the trade names of MicroMaxTM and MicroMax FF.
[0059] Further, to broaden the density range, it is possible to foam the
geopolymer
composition. The gas utilized to foam the composition can be air or nitrogen,
nitrogen being
the most preferred. The amount of gas present in the cement composition is
that amount
which is sufficient to form a foam having a density in the range of from about
I g.cm-, to
1.7 g.cm_3 (9 to 14 lbm/gal).
[0060] In a further embodiment, other additives can be used with the
geopolymer
according to the present invention. Additives known to those of ordinary skill
in the art may
be included in the geopolymer compositions of the present embodiments.
Additives are
typically blended with a base mix or may be added to the geopolymer
suspension. An
additive may comprise an activator, an antifoam, a defoamer, silica, a fluid
loss control
additive, a flow enhancing agent, a dispersant, an anti-settling additive or a
combination
thereof, for example. Selection of the type and amount of additive largely
depends on the
nature and composition of the set composition, and those of ordinary skill in
the art will
understand how to select a suitable type and amount of additive for
compositions herein.
[0061] In another embodiment, when various components are used with or within
the
geopolymer formulation, the particle size of the components is selected and
the respective
proportion of particles fractions is optimized in order to have at the same
time the highest
Packing Volume Fraction (PVF) of the solid, and obtaining a mixable and
pumpable slurry
with the minimum amount of water, i.e., at slurry Solid Volume Fraction (SVF)
of 35-75%
and preferably of 50-60%. More details can be found in European patent EP 0
621 247. The
following examples do not constitute a limit of the invention but rather
indicate to those
skilled in the art possible combinations of the particle size of
CA 02644991 2008-09-05
WO 2008/017414 PCT/EP2007/006815
the various components of the geopolymer compositions of the invention to make
a stable
and pumpable suspension.
[0062] The geopolymeric composition can be a "trimodal" combination of
particles:
"large" for example sand or crushed wastes (average dimension 100-1000
micrometers),
"medium" for example materials of the type of glass beads or fillers (average
dimension
10-100 micrometers), "fines" like for example a micromaterial, or micro fly
ashes or
other micro slags (average dimension 0.2-10 micrometers). The geopolymeric
composition can also be a "tetramodal" combination of particles type: with
"large"
(average dimension about 200-350 micrometers), "medium" glass beads, or
fillers
(average dimension about 10 - 20 micrometers), "fine" (average dimension about
1
micrometer), "very fine" (average dimension about 0.1 - 0.15 micrometer). The
geopolymeric composition can also be a further combinations between the
further
categories: "very large", for example glass maker sand, crushed wastes
(average
dimension superior to 1 millimeter) and/or "large", for example sand or
crushed wastes
(average dimension about 100-1000 micrometers) and/or "medium" like glass
beads, or
fillers, or crushed wastes (average dimension 10-100 micrometers) and "fine"
like, for
example, micro fly ashes or other micro slags (average dimension 0.2-10
micrometer)
and/or "very fine" like, for example, a latex or pigments or polymer microgels
like a
usual fluid loss control agent (average dimension 0.05-0.5 micrometer) and/or
"ultra
fine" like some colloidal silica or alumina (average dimension 7-50
nanometers).
Mechanical strength
[0063] The compressive mechanical properties of set geopolymer compositions
was
studied using systems after curing them for several days under high pressure
and
temperature in high pressure and high temperature chambers to simulate the
conditions
encountered in an oil or gas well.
Table 9 and 10 illustrate that geopolymer formulations proposed by this
invention exhibit
acceptable compressive strengths with low Young Modulus for oilfield
applications with
or without retarder.
21
CA 02644991 2008-09-05
WO 2008/017414 PCT/EP2007/006815
Sample A9 A9 B9 B9
Sodium pentaborate %bwob
0 1.8 0 1.8
Unconfined Compressive
Strength (UCS) MPa 19 14 15 13
Young's modulus
MPa 2400 2100 2300 3000
Table 9: Mechanical properties measured after 7 days at 90 C - 20.7MPa (3000
psi)
^ Sample A9 is made by dissolving the retarder amount (if necessary) in 358 g
of
water, adding the blend comprising 314 g of metakaolin and 227 g of sodium
disilicate in the solution under mixing, adding 17.2 g of sodium hydroxide
under
ISO 10426-2 mixing, pouring the suspension into moulds and placing the moulds
in a curing chamber for 7 days at 90 C - 20.7 MPa [3000 psi] according to ISO
10426-2 procedure. Sample A9 is then tested by measuring the compressive
strength and Young's modulus.
^ Sample B9 is made by dissolving the retarder amount (if necessary) in 265 g
of
water, adding the blend comprising 232 g of metakaolin, 168 g of sodium
disilicate and 414 g of silica particles as filler in the solution under
mixing, adding
13 g of sodium hydroxide under ISO 10426-2 mixing, pouring the suspension into
moulds and placing the moulds in a curing chamber for 7 days at 90 C - 20.7
MPa [3000 psi] according to ISO 10426-2 procedure. Sample B9 is then tested by
measuring the compressive strength and Young's modulus.
Sample A 10 B 10 CIO
Lithium chloride %bwob
0 3 7
Unconfined Compressive Strength (UCS)
MPa 9.5 9.5 9
Young's modulus
MPa 1750 2550 2950
Table 10: Mechanical properties measured after 21 days at 90 C - 20.7MPa
(3000psi)
^ Sample A10 is made by adding the blend comprising 482 g of standard type F
fly
ash and 96 g of sodium disilicate in 408 g of the sodium hydroxide solution
22
CA 02644991 2008-09-05
WO 2008/017414 PCT/EP2007/006815
containing the accelerator following ISO 10426-2 mixing, pouring the
suspension
into moulds and placing the moulds in a curing chamber for 21 days at 90 C -
20.7 MPa [3000 psi], according to ISO 10426-2 procedure. Sample A10 is then
tested by measuring the compressive strength and Young's modulus.
^ Sample B 10 is made by adding the blend comprising 442 g of standard type F
fly
ash and 88 g of sodium disilicate in 424 g of the sodium hydroxide solution
containing 3 %bwob LiCl following ISO 10426-2 mixing, pouring the suspension
into moulds and placing the moulds in a curing chamber for 21 days at 90 C -
20.7 MPa [3000 psi], according to ISO 10426-2 procedure. Sample B 10 is then
tested by measuring the compressive strength and Young's modulus.
^ Sample C 10 is made by adding the blend comprising 480 g of superfine type F
fly
ash and 96 g of sodium disilicate in 406 g of the sodium hydroxide solution
containing 7 %bwob LiCI following ISO 10426-2 mixing, pouring the suspension
into moulds and placing the moulds in a curing chamber for 21 days at 90 C -
20.7 MPa [3000 psi], according to ISO 10426-2 procedure. Sample CIO is then
tested by measuring the compressive strength and Young's modulus.
[0064] Because, the compositions of the present invention exhibit good
compressive
strengths with low Young modulus, they would be very useful in oilfield
applications.
Permeability properties
[0065] The water permeability were measured for some prepared geopolymer
compositions. The isolation properties of a set geopolymer was studied using
systems
which had passed several days under high pressure and temperature in high
pressure and
high temperature chambers to simulate the conditions encountered in an oil
well.
[0066] Table 11 illustrates that geopolymer formulations proposed by this
invention
exhibit acceptable permeability for oilfield applications.
23
CA 02644991 2008-09-05
WO 2008/017414 PCT/EP2007/006815
Sample All Bi l CI1 DI I
Water permeability [mD] 0.08 < 0.008 < 0.006 < 0.006
Table 11: Water permability measured after curing at 90 C - 20.7MPa (3000psi)
^ Sample All is made by dissolving the retarder amount in 265g of water,
adding
the blend comprising 232g of metakaolin, 168g of sodium disilicate and 414g of
silica particles as filler in the solution under mixing, adding 13g of sodium
hydroxyde under API mixing, pouring the suspension in molds in a curing
chamber for 7 days at 90 C - 3000psi according to API procedure. Water
permeability of sample AI 1 is then measured on cylindrical core (1-inch
diameter
by 2-inches length).
^ Sample B 11 is made by adding the blend comprising 482g of standard fly ash
type F and 96g of sodium disilicate in 408g of the sodium hydroxide solution
containing the accelerator following API mixing, pouring the suspension in
molds
in a curing chamber for 21 days at 90 C - 3000psi, according to API procedure.
Water permeability of sample B1I is then measured on cylindrical core (1-inch
diameter by 2-inches length).
^ Sample C 11 is made by adding the blend comprising 442g of standard fly ash
type F and 88g of sodium disilicate in 424g of the sodium hydroxide solution
containing 3% bwob LiCI following API mixing, pouring the suspension in molds
in a curing chamber for 21 days at 90 C - 3000psi, according to API procedure.
Water permeability of sample C 11 is then measured on cylindrical core (1-inch
diameter by 2-inches length).
^ Sample DII is made by adding the blend comprising 480g of superfine fly ash
type F and 96g of sodium disilicate in 406g of the sodium hydroxide solution
containing 7% bwob LiCI following API mixing, pouring the suspension in molds
in a curing chamber for 21 days at 90 C - 3000psi, according to API procedure.
24
CA 02644991 2008-09-05
WO 2008/017414 PCT/EP2007/006815
Water permeability of sample Di l is then measured on cylindrical core (1-inch
diameter by 2-inches length).
[0067] Because, the compositions of the present invention exhibit acceptable
water
permeability, oilfield applications are possible.
Applications of the geopolymer
[0068] The methods of the present invention are useful in completing well,
such as
for example oil and/or gas well, water well, geothermal well, steam injection
well, Toe to
Heel Air Injection well, acid gas well, carbon dioxide injection or production
well and
ordinary well. Placement of the geopolymer composition in the portion of the
wellbore to
be completed is accomplished by means that are well known in the art of
wellbore
cementing. The geopolymer composition is typically placed in a wellbore
surrounding a
casing to prevent vertical communication through the annulus between the
casing and the
wellbore or the casing and a larger casing. The geopolymer suspension is
typically placed
in a wellbore by circulation of the suspension down the inside of the casing,
followed by
a wiper plug and a nonsetting displacement fluid. The wiper plug is usually
displaced to a
collar, located near the bottom of the casing. The collar catches the wiper
plug to prevent
overdisplacement of the geopolymer composition and also minimizes the amount
of the
geopolymer composition left in the casing. The geopolymer suspension is
circulated up
the annulus surrounding the casing, where it is allowed to harden. The annulus
could be
between the casing and a larger casing or could be between the casing and the
borehole.
As in regular well cementing operations, such cementing operation with a
geopolymer
suspension may cover only a portion of the open hole, or more typically up to
inside the
next larger casing or sometimes up to surface. This method has been described
for
completion between formation and a casing, but can be used in any type of
completion,
for example with a liner, a slotted liner, a perforated tubular, an expandable
tubular, a
permeable tube and/or tube or tubing.
[0069] In the same way, the methods of the present invention are useful in
completing well, such as for example oil and/or gas well, water well,
geothermal well,
steam injection well, acid gas well, carbon dioxide well and ordinary well,
wherein
CA 02644991 2008-09-05
WO 2008/017414 PCT/EP2007/006815
placement of the geopolymer composition in the portion of the wellbore to be
completed
is accomplished by means that are well known in the art of wellbore reverse
circulation
cementing.
[0070] The geopolymer composition can also be used in squeeze job and/or in
remedial job. The geopolymer material is forced through perforations or
openings in the
casing, whether these perforations or openings are made intentionally or not,
to the
formation and wellbore surrounding the casing to be repaired. Geopolymer
material is
placed in this manner to repair and seal poorly isolated wells, for example,
when either
the original cement or geopolymer material fails, or was not initially placed
acceptably,
or when a producing interval has to be shut off.
[0071] The geopolymer composition can also be used in abandonment and/or
plugging job. The geopolymer material is used as a plug to shut off partially
or totally a
zone of the well. Geopolymer material plug is placed inside the well by means
that are
well known in the art of wellbore plug cementing.
[0072] The geopolymer composition can also be used in grouting job to complete
a
part of the annulus as described in Well Cementing from Erik B. Nelson. The
geopolymer
material is used to complete down this annulus. Geopolymer material is placed
inside the
well by means that are well known in the art of wellbore cementing.
[0073] The geopolymer composition can also be used for fast-setting operation,
in-
situ operation. Effectively, the geopolymer composition can have a setting
time perfectly
controlled, allowing an instant setting when desired. For example, a
retarder/accelerator
combination can be added to the geopolymer composition to cause the system to
be
retarded for an extended period of time and then to set upon addition of an
accelerator.
[0074] The geopolymer composition can also be a storable composition. As such,
the
suspension is over-retarder and is left intentionally in liquid phase. Said
suspension is so,
able to be stored and utilized in the well when needed.
[0075] According to other embodiments of the invention, the methods of
completion
described above can be used in combination with conventional cement
completion.
26
CA 02644991 2008-09-05
WO 2008/017414 PCT/EP2007/006815
Examples - Geopolymer compositions
[0076] The following examples will illustrate the practice of the present
invention in
its preferred embodiments.
Example 1
[0077] Geopolymer composition is made in the amounts by weight of the total
dry
components as follows: 58.1% metakaolin and 41.9% sodium disilicate. Dry
components
are mixed with the appropriate amount of water, sodium hydroxide and
additives. The
specific gravity of the suspension is 1.53 g/cm3 [ 12.80 lbm/gal]. The
geopolymer has the
following oxide molar ratios:
Si02/Al203=4.00
Na2O/SiO2=0.27
Na2O/A1203=1.07
H20/Na2O=17.15
Example 2
[0078] Geopolymer composition is made in the amounts by weight of the total
dry
components as follows: 28.5% metakaolin, 20.6% sodium disilicate and 50.9% of
a blend
of silica particles. Dry components are mixed with the appropriate amount of
water,
sodium hydroxide and additives. The specific gravity of the suspension is 1.84
g/cm3
[15.40 lbm/gal]. The geopolymer matrix has the following oxide molar ratios:
Si02/Al203=4.00
Na2O/SiO2=0.27
Na2O/Al203=1.07
H20/Na2O=17.15
27
CA 02644991 2008-09-05
WO 2008/017414 PCT/EP2007/006815
Example 3
[0079] Geopolymer composition is made in the amounts by weight of the total
dry
components as follows: 35.2% metakaolin and 64.2% potassium disilicate. Dry
components are mixed with the appropriate amount of water, potassium hydroxide
and
additives. The specific gravity of the suspension is 1.78 g/cm3 [14.91
lbm/gal]. The
geopolymer matrix has the following oxide molar ratios:
Si02/Al203=4.00
K20/SiO2=0.27
K20/A1203=1.07
H20/K20=17.46
Example 4
[0080] Geopolymer composition is made in the amounts by weight of the total
dry
components as follows: 83.3% standard fly ash type F and 16.7% sodium
disilicate. Dry
components are mixed with the appropriate amount of water, sodium hydroxide
and
additives. The specific gravity of the suspension is 1.66 g/cm3 [13.83
lbm/gal]. The
geopolymer has the following oxide molar ratios:
SiO2/A12O3=5.60
Na2O/SiO2=0.3
Na2O/A1203=1.08
H20/Na2O=13.01
28
