CA2644991C - Pumpable geopolymer formulation for oilfield application - Google Patents

Abstract

The invention provides geopolymeric compositions, which have controllable thickening and setting times for a wide range of temperatures and a large range of geopolymer slurry densities. The geopolymer slurry compositions have good mixability and pumpability, whilst the set materials develop good compressive strength and permeability. The invention discloses a method for preparing geopolymer for oilfield cementing applications. The geopolymeric compositions according to the invention comprises a suspension made of 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 the suspension is a pumpable composition in oilfield industry and the suspension is able to set under well downhole conditions.

Description

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

[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 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 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 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 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 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, 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.

[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 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.

[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 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 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 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 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).

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, 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 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

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.

^ 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.

^ 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.

^ 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 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 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 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.

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 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 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.

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.

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 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.

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 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

Claims (52)

What is claimed is:

1. 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.

2. The suspension of claim 1, further comprising a retarder for controlling the thickening and/or the setting times of the suspension under well downhole conditions.

3. The suspension of claim 2, wherein the retarder comprises boron containing compound, lignosulfate, sodium gluconate, sodium glucoheptonate, tartaric acid, phosphorus containing compound, or a mixture thereof.

4. The suspension according to any one of claims 2 to 3, wherein the retarder is efficient from 20°C to 200°C.

5. The suspension according to any one of claims 1 to 4, further comprising an accelerator for controlling the thickening and/or the setting times of the suspension.

6. The suspension of claim 5, wherein the accelerator is an alkali metal containing compound.

7. The suspension of claim 6, wherein the accelerator is a lithium or potassium compound.

8. The suspension according to any one of claims 5 to 7, wherein the accelerator is efficient from 20°C to 200°C.

9. The suspension according to any one of claims 1 to 8, further comprising a lightweight particle selected from cenospheres, sodium-calcium-borosilicate glass, and silica-alumina microspheres.

10. The suspension according to any one of claims 1 to 9, further comprising a heavy particle selected from manganese tetraoxide, iron oxide (hematite), barium sulfate (barite), silica and iron/titanium oxide (ilmenite).

11. The suspension according to any one of claims 1 to 10, further comprising a gas phase.

12. The suspension of claim 11, wherein the gas phase is air or nitrogen.

13. The suspension of claim 11, further comprising a gas generating additive for generating a gas phase within the suspension.

14. The suspension according to any one of claims 1 to 13, further comprising a water-immiscible phase.

15. The suspension of claim 14, wherein the water-immiscible phase is an oil-based phase.

16. The suspension according to any one of claims 1 to 15, wherein the density of the suspension varies between 1 gram per cubic centimeter and 2.5 grams per cubic centimeter.

17. The suspension according to any one of claims 1 to 16, further comprising an additive selected from 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.

18. 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.

19. The suspension of claim 18, wherein the oxide molar ratio M2O/SiO2 is greater than or equal to 0.25.

20. The suspension according to any one of claims 18 to 19, wherein the retarder is a boron containing compound and wherein the suspension of said geopolymeric composition has an oxide molar ratio B203/1-120 of less than 0.03.

21. The suspension of claim 20, wherein the oxide molar ratio B203/H20 is less than or equal to 0.02.

22. The suspension according to any one of claims 18 to 21, wherein the silicon to aluminum atomic ratio is between 1.8 and 2.8.

23. The suspension of claim 22, wherein the silicon to aluminum atomic ratio is equal to two.

24. The suspension according to any one of claims 18 to 23, wherein the aluminosilicate source is selected from type C fly ash, type F fly ash, ground blast furnace slag, calcined clays, metakaolin, aluminium-containing silica fume, kaolin, synthetic aluminosilicate glass powder, zeolite, scoria, allophone, bentonite and pumice.

25. The suspension according to any one of claims 18 to 24, wherein the metal is selected from lithium, sodium, potassium, rubidium, and cesium.

26. The suspension according to any one of claims 18 to 25, wherein the alkali activator is an alkali metal hydroxide.

27. The suspension according to any one of claims 18 to 26, wherein the alkali activator is encapsulated.

28. The suspension according to any one of claims 18 to 27, wherein the metal silicate is encapsulated.

29. 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:

(i) a retarder and/or an accelerator;
(ii) an aluminosilicate source;

(iii) an activator comprising a metal silicate, a metal aluminate, an alkali activator, or a combination thereof.

30. The method of claim 29, wherein the method applies for temperature ranges from 20°C to 200°C.

31. The method according to any one of claims 29 to 30, wherein the alkali activator is selected from sodium hydroxide and potassium hydroxide, whether encapsulated or not.

32. The method according to any one of claims 29 to 31, wherein the retarder is selected from boron containing compound, lignosulfate, sodium gluconate, sodium glucoheptonate, tartaric acid and phosphorus containing compounds, or a mixture thereof.

33. The method according to any one of claims 29 to 32, wherein the accelerator is an alkali metal containing compound.

34. The method of claim 33, wherein the accelerator is a lithium or potassium compound.

35. The method according to any one of claims 29 to 34, wherein the retarder and/or the accelerator is encapsulated.

36. The method according to any one of claims 29 to 35, wherein the thickening and/or the setting times are controlled by changing the nature and/or the concentration of the retarder and/or accelerator.

37. The method according to any one of claims 29 to 36, wherein the thickening and/or the setting times are controlled by changing the pH and/or the concentration of the alkali activator.

38. 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:

(i) lightweight particles and/or heavy particles;
(ii) an aluminosilicate source;

(iii) an activator comprising a metal silicate, a metal aluminate, an alkali activator, or a combination thereof.

39. The method of claim 38, further comprising the step of adding 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.

40. The method of claim 38 or 39, further comprising the step of foaming the suspension of said geopolymeric composition.

41. A method to control the density of a geopolymer suspension for oilfield industry, comprising the step of:

(i) 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 (ii) foaming said suspension.

42. The method according to any one of claims 38 to 41, wherein the density range varies between 1 gram per cubic centimeter and 2.5 grams per cubic centimeter.

43. A method to place a geopolymeric composition in a borehole in a formation comprising the step of:

(i) 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, (ii) pumping said suspension into the borehole, and (iii) allowing said suspension to set under wellbore downhole conditions and thereby form the geopolymeric composition.

44. The method of claim 43, wherein the step of providing a suspension further comprises adding a retarder able to retard the thickening and/or the setting times of the suspension.

45. The method of claim 43 or 44, wherein the step of providing a suspension further comprises adding an accelerator for accelerating the thickening and/or the setting times of the suspension.

46. The method according to any one of claims 43 to 45, further comprising the step of activating in situ said suspension.

47. The method according to any one of claims 43 to 46, wherein the step of pumping the suspension is made with conventional tools of wellbore cementing.

48. The method according to any one of claims 43 to 48, wherein the method applies to the placement of the geopolymeric composition in an annular space between a casing and the borehole.

49. The method according to any one of claims 43 to 48, wherein the method applies to the placement of the geopolymeric composition through a hole made in a casing.

50. The method according to any one of claims 43 to 48, wherein the method applies to the placement of the geopolymeric composition to plug a zone of the borehole.

51. The method according to any one of claims 43 to 48, wherein the method applies to the placement of the geopolymeric composition to squeeze a zone of the borehole.

52. The method according to any one of claims 43 to 50, wherein the suspension is prepared before the step of pumping and is left intentionally in a liquid phase able to be stored.