Geopolymer raw material composition, geopolymer precursor slurry and applications and method of high temperature well cementation

Abstract

The present application relates to the field of geopolymer, and discloses a geopolymer raw material composition, a geopolymer precursor slurry, applications and a high-temperature well cementing method.The geopolymer raw material composition comprises calcined kaolin, an organic polymer, an activator and a cosolvent; wherein the organic polymer is chitosan and / or polyvinylpyrrolidone. The geopolymer raw material composition can be used to prepare a geopolymer precursor slurry with delayed curing performance, and further curing can obtain a geopolymer. The geopolymer precursor slurry has a curing time of 120-480 min at 80-120 DEG C, a fluidity of no less than 18 cm, a compressive strength of the geopolymer after 1 day of curing of greater than 7 MPa, and a compressive strength of the geopolymer after 3 days of curing of greater than 14 MPa, realizing the extension of the curing time of the polymer precursor slurry under high-temperature conditions and meeting the requirements of high-temperature oil and gas well cementing construction.

Description

Technical Field

[0001] This invention relates to the field of geopolymers, and more particularly to a geopolymer raw material composition, a geopolymer precursor slurry, its application, and a method for high-temperature cementing. Background Technology

[0002] Geopolymers are a type of material formed from calcined kaolin and other alkali-active aluminosilicate materials under the action of an alkali activator, consisting of [SiO4]. 4- and [AlO4] 5- Geopolymers are three-dimensional, network-structured silica-alumina cementitious materials composed of structural units. Compared to traditional cement, geopolymers can reduce energy consumption by over 70% and carbon emissions by over 80% during preparation, with no sulfur or nitrogen oxide emissions, hence they are also known as "green cement." Geopolymers possess advantages such as high-temperature stability, excellent mechanical properties, corrosion resistance, and durability, making them a highly promising non-traditional cementitious material with the potential to replace traditional silicate cement.

[0003] Although geopolymers have better physical and chemical properties than silicate cement, they suffer from excessively rapid hydration, making it difficult to meet operational requirements in many cases and hindering their widespread use, especially in oilfield cementing projects. Their main drawbacks are twofold: (1) short curing time, particularly uncontrollable curing time at high temperatures, affecting construction safety; and (2) high slurry consistency. Therefore, controlling the slurry curing time during geopolymer preparation is crucial.

[0004] CN108947298A discloses a geopolymer reinforcing retarder, which is an aqueous solution composed of one or more of sugar compounds and sugar alcohols, wherein the amount percentage is 0-80% sugar compounds, 0-80% sugar alcohols, and 10-90% water. This retarder can prolong the setting time of geopolymers, improve their workability, and enhance their compressive strength.

[0005] CN101323778A discloses a metakaolin-slag-based polymer for oilfield cementing and its high-temperature retarder. The high-temperature retarder comprises 80-90% alkaline earth metal salt and 10-20% inorganic sulfate; wherein the alkaline earth metal salt is one or a combination of magnesium chloride, calcium chloride, barium chloride, calcium nitrate, and barium nitrate. This high-temperature retarder can control the setting rate of the metakaolin-slag-based polymer for oilfield cementing under high-temperature conditions and regulate key properties such as curing time and strength.

[0006] The above methods all control the curing time of geopolymer precursor slurry by adding high-performance retarders other than those in the geopolymer system, without involving any improvement to the raw materials used to prepare the geopolymer. Summary of the Invention

[0007] This invention addresses the problem of rapid hydration of raw materials during the preparation of geopolymers, especially the excessively rapid solidification and difficulty in controlling the precursor slurry under high-temperature downhole environments. It provides a geopolymer raw material composition, a geopolymer precursor slurry, its application, and a method for high-temperature cementing.

[0008] To achieve the above objectives, the first aspect of the present invention provides a geopolymer raw material composition comprising: calcined kaolin, an organic polymer, an activator, and a co-solvent; wherein, relative to 100 parts by weight of the calcined kaolin, the organic polymer is 0.4-1.6 parts by weight and the activator is 9-70 parts by weight.

[0009] The organic polymer is chitosan and / or polyvinylpyrrolidone.

[0010] A second aspect of the present invention provides a geopolymer precursor slurry comprising: water, calcined kaolin coated with an organic polymer, and an activator;

[0011] Relative to 100 parts by weight of the organic polymer-coated calcined kaolin, the activator is 8.9-69.7 parts by weight and the water is 50-100 parts by weight;

[0012] The organic polymer-coated calcined kaolin is obtained by coating the surface of calcined kaolin with an organic polymer in the presence of a cosolvent; the organic polymer is chitosan and / or polyvinylpyrrolidone.

[0013] The third aspect of this invention provides the application of the geopolymer precursor slurry described in the second aspect above in high-temperature cementing.

[0014] A fourth aspect of the present invention provides a method for high-temperature cementing, wherein the method includes: injecting the geopolymer precursor slurry described in the second aspect below into the well, obtaining a geopolymer after solidification, and using the geopolymer for cementing;

[0015] Curing conditions include: temperature of 80-120℃ and pressure of 30-70MPa.

[0016] Through the above technical solution, the geopolymer precursor slurry with delayed curing properties can be prepared using the geopolymer raw material composition provided by the present invention, and further cured to obtain the geopolymer. The geopolymer precursor slurry has a curing time of 120-480 min at 80-120℃, a fluidity of not less than 18 cm, a compressive strength of greater than 7 MPa after 1 day of curing, and a compressive strength of greater than 14 MPa after 3 days of curing. This can extend the curing time of the polymer precursor slurry under high temperature conditions, thereby meeting the requirements of oil and gas well cementing construction. Detailed Implementation

[0017] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0018] The first aspect of the present invention provides a geopolymer raw material composition comprising: calcined kaolin, an organic polymer, an activator, and a co-solvent; wherein, relative to 100 parts by weight of the calcined kaolin, the organic polymer is 0.4-1.6 parts by weight and the activator is 9-70 parts by weight.

[0019] The organic polymer is chitosan and / or polyvinylpyrrolidone.

[0020] According to the present invention, based on the above, preferably, the components in the geopolymer raw material composition satisfy the following quantitative relationship: relative to 100 parts by weight of the calcined kaolin, the organic polymer is 0.8-1.2 parts by weight and the activator is 35-50 parts by weight.

[0021] According to the present invention, the organic polymer can achieve surface coating of the calcined kaolin particles, forming an organic polymer coating layer on the surface of the calcined kaolin particles. Preferably, the organic polymer is chitosan.

[0022] According to the present invention, the calcined kaolin is obtained by calcining kaolin ore at high temperature. Generally, kaolin ore exhibits activity after calcination at 600-850℃, with the strongest activity observed after calcination at 700-750℃. For the purpose of controlling the reactivity of the calcined kaolin, preferably, the calcined kaolin used in the present invention is obtained by calcining kaolin ore at 600-650℃ or 800-850℃.

[0023] According to this method, the smaller the particle size of the calcined kaolin used as an active aluminosilicate material for preparing geopolymers, the larger its specific surface area and the significantly higher its reactivity, which is detrimental to controlling the curing time. For the purpose of controlling the reactivity of the calcined kaolin, preferably, the average particle size of the aluminosilicate raw material is 80-160 mesh.

[0024] The present invention has a wide range of restrictions on the source of the calcined kaolin. It can be obtained by self-production using conventional methods or by commercially purchased products, as long as the above-mentioned calcination temperature and particle size restrictions are met.

[0025] According to the present invention, the activator can be any conventional alkaline activator used in the preparation of geopolymers. Preferably, the activator comprises an inorganic strong alkaline compound and an organic weak alkaline compound. In the present invention, the inorganic strong alkaline compound has strong alkalinity, while the organic weak alkaline compound has relatively weak alkalinity. By using the two in combination, the alkalinity of the activator can be reduced, which is beneficial for controlling the curing time.

[0026] According to the present invention, relative to 100 parts by weight of the calcined kaolin, the inorganic strong alkaline compound is 4-30 parts by weight, preferably 15-20 parts by weight; the organic weak alkaline compound is 5-40 parts by weight, preferably 20-30 parts by weight.

[0027] According to the present invention, preferably, the inorganic strong basic compound is selected from at least one of sodium hydroxide, potassium hydroxide, sodium silicate, and potassium silicate; and the organic weak basic compound is selected from at least one of methylamine, ethylenediamine, and triethylamine.

[0028] According to the present invention, the co-solvent is selected from at least one of hydrochloric acid, sulfuric acid and nitric acid.

[0029] The geopolymer raw material composition provided by the present invention contains a specific organic polymer and a co-solvent. The organic polymer can coat the calcined kaolin in the composition in the presence of the co-solvent to obtain organic polymer-coated calcined kaolin. Then, with the addition of an activator, a delayed-curing geopolymer precursor slurry and a geopolymer can be obtained after treatment.

[0030] According to the present invention, the cosolvent in the composition plays the role of cosolventizing the organic polymer in the process of preparing the organic polymer-coated calcined kaolin. The amount used is extremely low compared to other components in the composition. Therefore, the amount of cosolvent is not reflected in the quantity limits of each component in the composition of the present invention.

[0031] According to the present invention, the process of preparing organic polymer-coated calcined kaolin by surface coating of calcined kaolin with the organic polymer in the composition includes: mixing the organic polymer, co-solvent and added water in proportion to the composition to obtain an organic polymer solution; mixing the organic polymer solution with the calcined kaolin, and then performing post-treatment to obtain organic polymer-coated calcined kaolin.

[0032] According to the present invention, in the process of preparing the organic polymer-coated calcined kaolin described above, the content of the organic polymer in the organic polymer solution is 0.5-0.8 wt%.

[0033] According to the present invention, in the process of preparing the organic polymer-coated calcined kaolin described above, the amount of the co-solvent is such that the pH value of the organic polymer solution is 4-6.

[0034] According to the present invention, in the process of preparing the organic polymer-coated calcined kaolin as described above, the organic polymer solution is mixed with the calcined kaolin to obtain a suspension, preferably the suspension is adjusted to a pH value of 9-11, and then the post-treatment is performed.

[0035] According to the present invention, in the process of preparing the organic polymer-coated calcined kaolin described above, the post-treatment includes drying and crushing to obtain calcined kaolin coated with organic polymer at a mesh size of 80-160.

[0036] Using the geopolymer raw material composition provided by this invention, after raw material processing, a geopolymer precursor slurry can be obtained by mixing with water. After solidification, the geopolymer is obtained. The calcined kaolin in the composition exhibits moderate reactivity after particle size screening. Furthermore, the organic polymer in the composition is used to coat its surface, forming an organic polymer coating layer. This isolates the calcined kaolin particles from the activator in the initial stage of subsequent slurry hydration. As the precursor slurry system penetrates deeper into the well and the temperature gradually increases, the organic polymer coating layer gradually dissolves, slowly releasing the calcined kaolin particles. This allows the particles to gradually contact and react with the activator, thus delaying the reaction process and consequently extending the solidification time of the precursor slurry. Using the composition of this invention as raw material, the geopolymer precursor slurry can be prepared with a solidification time of 120-480 min at 80-120℃, a fluidity of not less than 18 cm, a compressive strength greater than 7 MPa after 1 day of solidification, and a compressive strength greater than 14 MPa after 3 days of solidification.

[0037] A second aspect of the present invention provides a geopolymer precursor slurry comprising: water, calcined kaolin coated with an organic polymer, and an activator;

[0038] Relative to 100 parts by weight of the organic polymer-coated calcined kaolin, the activator is 8.9-69.7 parts by weight and the water is 50-100 parts by weight;

[0039] The organic polymer-coated calcined kaolin is obtained by coating the surface of calcined kaolin with an organic polymer in the presence of a cosolvent; the organic polymer is chitosan and / or polyvinylpyrrolidone.

[0040] According to the present invention, the calcined kaolin, the organic polymer, and the activator contained in the geopolymer precursor slurry used to prepare the organic polymer-coated calcined kaolin satisfy the following quantitative relationship: relative to 100 parts by weight of the calcined kaolin, the organic polymer is 0.4-1.6 parts by weight and the activator is 9-70 parts by weight.

[0041] Preferably, relative to 100 parts by weight of the calcined kaolin, the organic polymer is 0.8-1.2 parts by weight and the activator is 35-50 parts by weight.

[0042] According to the present invention, the organic polymer can coat the calcined kaolin particles, forming an organic polymer coating layer on their surface. This isolates the calcined kaolin particles from the activator in the initial stage of subsequent slurry hydration. As the temperature increases, the organic polymer coating layer gradually dissolves, allowing the calcined kaolin particles to gradually come into contact with the activator and react, thus delaying the reaction process.

[0043] According to the present invention, preferably, the organic polymer is chitosan.

[0044] According to the present invention, the calcined kaolin is obtained by calcining kaolin ore at high temperature. Generally, kaolin ore exhibits activity after calcination at 600-850℃, with the strongest activity observed after calcination at 700-750℃. For the purpose of controlling the reactivity of the calcined kaolin, preferably, the calcined kaolin used in the present invention is obtained by calcining kaolin ore at 600-650℃ or 800-850℃.

[0045] According to the present invention, the smaller the particle size of the calcined kaolin as an active aluminosilicate material for preparing geopolymers, the larger its specific surface area and the significantly higher its reactivity, which is detrimental to controlling the curing time. For the purpose of controlling the reactivity of the calcined kaolin, preferably, the average particle size of the calcined kaolin is 80-160 mesh.

[0046] The present invention has a wide range of restrictions on the source of the calcined kaolin. It can be obtained by self-production using conventional methods or by commercially purchased products, as long as the above-mentioned calcination temperature and particle size restrictions are met.

[0047] According to the present invention, the preparation process of the organic polymer-coated calcined kaolin includes: mixing the organic polymer, a co-solvent, and added water (the added water is used in the preparation stage of the organic polymer-coated calcined kaolin and is removed by post-treatment in subsequent steps of preparation; it is not included in the component water of the geopolymer precursor slurry) according to the above proportions to obtain an organic polymer solution; mixing the organic polymer solution with the calcined kaolin, and then performing post-treatment to obtain organic polymer-coated calcined kaolin.

[0048] According to the present invention, in the process of preparing the organic polymer-coated calcined kaolin described above, the content of the organic polymer in the organic polymer solution is 0.5-0.8 wt%.

[0049] According to the present invention, in the process of preparing the organic polymer-coated calcined kaolin described above, the amount of the co-solvent is such that the pH value of the organic polymer solution is 4-6.

[0050] According to the present invention, in the process of preparing the organic polymer-coated calcined kaolin as described above, the organic polymer solution is mixed with the calcined kaolin to obtain a suspension, preferably the suspension is adjusted to a pH value of 9-11, and then the post-treatment is performed.

[0051] According to the present invention, in the process of preparing the organic polymer-coated calcined kaolin described above, the post-treatment includes drying and crushing to obtain calcined kaolin coated with organic polymer at a mesh size of 80-160.

[0052] According to the present invention, the activator can be any conventional alkaline activator used in the preparation of geopolymers. Preferably, the activator comprises an inorganic strong alkaline compound and an organic weak alkaline compound. In the present invention, the inorganic strong alkaline compound has strong alkalinity, while the organic weak alkaline compound has relatively weak alkalinity. By using the two in combination, the alkalinity of the activator can be reduced, which is beneficial for controlling the curing time.

[0053] According to the present invention, preferably, the inorganic strong basic compound is selected from at least one of sodium hydroxide, potassium hydroxide, sodium silicate, and potassium silicate; and the organic weak basic compound is selected from at least one of methylamine, ethylenediamine, and triethylamine.

[0054] According to the present invention, the co-solvent is selected from at least one of hydrochloric acid, sulfuric acid and nitric acid.

[0055] The geopolymer precursor slurry provided by this invention contains organic polymer-coated calcined kaolin, obtained by coating the surface of calcined kaolin after particle size screening with a specific organic polymer. The calcined kaolin, after particle size screening to control its specific surface area and activity, and further coated with an organic polymer shell, acquires slow-release properties. Specifically, in the initial stage of hydration of the organic polymer-coated calcined kaolin with an activator and water, the organic polymer shell isolates the calcined kaolin particles from the activator. As the precursor slurry system penetrates deeper into the well and the temperature gradually increases, the organic polymer coating gradually dissolves, slowly releasing the calcined kaolin particles, which then gradually come into contact with the activator and react, thus delaying the reaction process. This gives the geopolymer precursor slurry of this invention delayed solidification properties, maintaining excellent retarding effects even at high temperatures. Specifically, the geopolymer precursor slurry has a curing time of 120-480 min at 80-120℃, a fluidity of not less than 18 cm, a compressive strength of greater than 7 MPa after 1 day of curing, and a compressive strength of greater than 14 MPa after 3 days of curing.

[0056] According to a preferred embodiment of the present invention, the geopolymer precursor slurry has a curing time of more than 140 min and a flowability of more than 19 cm under conditions of 80-120°C. After curing for 1 day, the compressive strength of the geopolymer is greater than 8 MPa, and after curing for 3 days, the compressive strength of the geopolymer is greater than 16 MPa.

[0057] According to the present invention, the geopolymer precursor slurry can be prepared by mixing its constituent components. For example, the activator and organic polymer-coated calcined kaolin are sequentially added to water (referring to the slurry preparation water) and stirred thoroughly to obtain a homogeneous mixture, which is the geopolymer precursor slurry; wherein, relative to 100 parts by weight of the organic polymer-coated calcined kaolin, the activator is 8.9-69.7 parts by weight and the water is 50-100 parts by weight.

[0058] The third aspect of this invention provides the application of the geopolymer precursor slurry described in the second aspect above in high-temperature cementing.

[0059] A fourth aspect of the present invention provides a method for high-temperature cementing, wherein the method includes: injecting the geopolymer precursor slurry described in the second aspect below into the well, obtaining a geopolymer after solidification, and using the geopolymer for cementing;

[0060] Curing conditions include: temperature of 80-120℃ and pressure of 30-70MPa.

[0061] According to the present invention, the geopolymer precursor slurry has a curing time of 120-480 min at 80-120℃, a flowability of 18-22 cm, a compressive strength of the geopolymer greater than 7 MPa after 1 day of curing, and a compressive strength of greater than 14 MPa after 3 days of curing.

[0062] The present invention will be described in detail below through embodiments. In the following embodiments and comparative examples,

[0063] Flowability: Measured according to GB / T 8077-2012 method;

[0064] Compressive strength: Measured according to the method specified in GB / T 19139-2012;

[0065] Curing time: Measured according to the method specified in GB / T 19139-2012.

[0066] Unless otherwise specified, all materials used are common commercially available products.

[0067] Example 1

[0068] Preparation of calcined kaolin: Kaolin ore is crushed and ground, and kaolin powder with an average particle size of 100 mesh is screened out. It is then calcined at 650℃ for 2 hours and naturally cooled to room temperature to obtain calcined kaolin (100 mesh).

[0069] The geological polymer raw material composition used is: calcined kaolin (100 parts by weight), chitosan (0.8 parts by weight), sodium hydroxide (15 parts by weight), methylamine (20 parts by weight), and hydrochloric acid.

[0070] Preparation of geopolymer precursor slurry: All the chitosan, hydrochloric acid and added water in the above composition are mixed to obtain a chitosan solution with a pH of 4.5 (chitosan content of 0.6 wt%); all the calcined kaolin in the above composition is mixed with all the aforementioned chitosan solution to obtain a suspension, and the pH of the suspension is adjusted to 9.5 using sodium hydroxide aqueous solution, then filtered, dried and crushed to obtain 100-mesh chitosan-coated calcined kaolin (100.8 parts by weight); 70 parts by weight of water are taken, and all the sodium hydroxide (15 parts by weight) and methylamine (20 parts by weight) in the above composition are added and stirred and mixed, then all the chitosan-coated calcined kaolin is added and stirred and mixed evenly to obtain geopolymer precursor slurry (denoted as P1).

[0071] The flowability of P1 is 20 cm. P1 was tested at 80℃, 90℃, 100℃, 110℃, and 120℃ (all at 50 MPa), and the curing time and compressive strength of the geopolymer obtained after 1 day and 3 days of curing were recorded. The results are shown in Table 1.

[0072] Table 1

[0073]

[0074] Example 2

[0075] Calcined kaolin was prepared according to the method and parameters of Example 1.

[0076] The geological polymer raw material composition used is: calcined kaolin (100 parts by weight), chitosan (1.2 parts by weight), sodium hydroxide (20 parts by weight), methylamine (30 parts by weight), and hydrochloric acid.

[0077] Preparation of geopolymer precursor slurry: All the chitosan, hydrochloric acid and added water in the above composition are mixed to obtain a chitosan solution with a pH of 5.5 (chitosan content of 0.7 wt%); all the calcined kaolin in the above composition is mixed with all the aforementioned chitosan solution to obtain a suspension, and the pH of the suspension is adjusted to 10.5 using sodium hydroxide aqueous solution, then filtered, dried and crushed to obtain 100-mesh chitosan-coated calcined kaolin (101.2 parts by weight); 80 parts by weight of water are taken, and all the sodium hydroxide (20 parts by weight) and methylamine (30 parts by weight) in the above composition are added and stirred and mixed, then all the chitosan-coated calcined kaolin is added and stirred and mixed evenly to obtain geopolymer precursor slurry (denoted as P2).

[0078] The flowability of P2 is 20 cm. P2 was tested at 80℃, 90℃, 100℃, 110℃, and 120℃ (all at 50 MPa), and the curing time and compressive strength of the geopolymer obtained after 1 day and 3 days of curing were recorded. The results are shown in Table 2.

[0079] Table 2

[0080]

[0081] Example 3

[0082] Calcined kaolin was prepared according to the method and parameters of Example 1.

[0083] The geological polymer raw material composition used is: calcined kaolin (100 parts by weight), chitosan (2 parts by weight), sodium silicate (30 parts by weight), triethylamine (40 parts by weight), and nitric acid.

[0084] Preparation of geopolymer precursor slurry: All the chitosan, nitric acid and added water in the above composition are mixed to obtain a chitosan solution with a pH of 6 (chitosan content is 0.8 wt%); all the calcined kaolin in the above composition is mixed with all the aforementioned chitosan solution to obtain a suspension, and the pH of the suspension is adjusted to 11 using sodium hydroxide aqueous solution, then filtered, dried and crushed to obtain 100-mesh chitosan-coated calcined kaolin (102 parts by weight); 100 parts by weight of water is taken, and all the sodium silicate (30 parts by weight) and triethylamine (40 parts by weight) in the above composition are added and stirred and mixed, then all the chitosan-coated calcined kaolin is added and stirred and mixed evenly to obtain geopolymer precursor slurry (denoted as P3).

[0085] The flowability of P3 is 22 cm. P3 was tested at 80℃, 90℃, 100℃, 110℃, and 120℃ (all at 50 MPa), and the curing time and compressive strength of the geopolymer obtained 1 day and 3 days after curing were recorded. The results are shown in Table 3.

[0086] Table 3

[0087]

[0088] Example 4

[0089] Calcined kaolin was prepared according to the method and parameters of Example 1.

[0090] The above-mentioned calcined kaolin (100 parts by weight), polyvinylpyrrolidone (0.1 parts by weight), potassium hydroxide (4 parts by weight), ethylenediamine (5 parts by weight), and sulfuric acid.

[0091] Preparation of geopolymer precursor slurry: Mix all of the polyvinylpyrrolidone, sulfuric acid and added water in the above composition to obtain a polyvinylpyrrolidone solution with a pH of 4 (polyvinylpyrrolidone content is 0.5 wt%); mix all of the calcined kaolin in the above composition with all of the aforementioned polyvinylpyrrolidone solution to obtain a suspension, and adjust the pH of the suspension to 9 using sodium hydroxide aqueous solution, then filter, dry and crush to obtain 100-mesh polyvinylpyrrolidone-coated calcined kaolin (100.1 parts by weight); take 50 parts by weight of water, add all of the potassium hydroxide inorganic alkaline compound (4 parts by weight) and ethylenediamine organic alkaline compound (5 parts by weight) in the above composition, stir and mix, then add all of the above polyvinylpyrrolidone-coated calcined kaolin, continue stirring and mixing evenly to obtain geopolymer precursor slurry (denoted as P4).

[0092] The flowability of P4 is 18 cm. P4 was tested at 80℃, 90℃, 100℃, 110℃, and 120℃ (all at 50 MPa), and the curing time and compressive strength of the geopolymer obtained after 1 day and 3 days of curing were recorded. The results are shown in Table 4.

[0093] Table 4

[0094]

[0095] Example 5

[0096] Calcined kaolin was prepared according to the method in Example 1, except that the calcination temperature was 750°C.

[0097] Geopolymer raw material composition: Based on the raw material composition of Example 1, the calcined kaolin obtained by calcination at 650°C is replaced with an equal amount of the calcined kaolin obtained by calcination at 750°C.

[0098] Using the above-mentioned geopolymer raw material composition, a geopolymer precursor slurry (denoted as P5) was prepared according to the method and parameters of Example 1.

[0099] The flowability of P5 is 16 cm. P5 was tested at 80℃, 90℃, 100℃, 110℃, and 120℃ (all at 50 MPa), and the curing time and compressive strength of the geopolymer obtained 1 day and 3 days after curing were recorded. The results are shown in Table 5.

[0100] Table 5

[0101]

[0102] Note: "-" indicates that the curing time has not met the requirements, and strength data will not be measured.

[0103] Example 6

[0104] Calcined kaolin was prepared according to the method in Example 1, except that the average particle size of the calcined kaolin was 160 mesh.

[0105] Geopolymer raw material composition: Based on the raw material composition of Example 1, the 100-mesh calcined kaolin in it is replaced with an equal amount of the above-mentioned 160-mesh calcined kaolin.

[0106] Using the above-mentioned geopolymer raw material composition, and following the method and parameters of Example 1 (wherein the average particle size of the chitosan-coated calcined kaolin is 160 mesh), a geopolymer precursor slurry (denoted as P6) was prepared.

[0107] The flowability of P6 is 20 cm. P6 was tested at 80℃, 90℃, 100℃, 110℃, and 120℃ (all at 50 MPa), and the curing time and compressive strength of the geopolymer obtained 1 day and 3 days after curing were recorded. The results are shown in Table 6.

[0108] Table 6

[0109]

[0110] Note: "-" indicates that the curing time has not met the requirements, and strength data will not be measured.

[0111] Comparative Example 1

[0112] Calcined kaolin was prepared according to the method in Example 1.

[0113] The geological polymer raw material composition used is: calcined kaolin (100 parts by weight), sodium hydroxide (15 parts by weight), and methylamine (20 parts by weight).

[0114] Preparation of geopolymer precursor slurry: Take 70 parts by weight of water, add all of the sodium hydroxide (15 parts by weight) and methylamine (20 parts by weight) in the above composition, stir and mix, then add all of the calcined kaolin (100 parts by weight) in the above composition, continue stirring and mixing evenly to obtain geopolymer precursor slurry (denoted as D1).

[0115] The flowability of D1 is 15 cm. D1 was tested at 80℃, 90℃, 100℃, 110℃, and 120℃ (all at 50 MPa), and the curing time and compressive strength of the geopolymer obtained 1 day and 3 days after curing were recorded. The results are shown in Table 7.

[0116] Table 7

[0117]

[0118]

[0119] Note: "-" indicates that the curing time has not met the requirements, and strength data will not be measured.

[0120] As can be seen from the above examples and comparative examples, the geopolymer precursor slurry prepared using the geopolymer raw material composition of the present invention has delayed curing properties, a fluidity of not less than 18 cm, a curing time of 120-480 min at 80-120℃, and a compressive strength of the geopolymer obtained after 1 day of curing greater than 7 MPa and after 3 days of curing greater than 14 MPa. The curing time, curing strength, and fluidity all meet the requirements for cementing operations. Among the above examples 1-6, examples 1-2 have a greater comprehensive advantage in terms of curing time and curing strength. In contrast, Comparative Example 1 did not use the geopolymer raw material composition of the present invention, and the resulting geopolymer precursor slurry did not possess delayed curing properties, making it difficult to meet the requirements for cementing operations.

[0121] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A geopolymer raw material composition, characterized in that, The geopolymer raw material composition comprises: calcined kaolin, an organic polymer, an activator, and a co-solvent; relative to 100 parts by weight of the calcined kaolin, the organic polymer is 0.4-1.6 parts by weight and the activator is 9-70 parts by weight. Wherein, the organic polymer is chitosan and / or polyvinylpyrrolidone; The organic polymer is used to coat the calcined kaolin in the presence of a cosolvent to obtain organic polymer-coated calcined kaolin.

2. The geopolymer raw material composition according to claim 1, wherein, The organic polymer is 0.8-1.2 parts by weight and the activator is 35-50 parts by weight relative to 100 parts by weight of the calcined kaolin.

3. The geopolymer raw material composition according to claim 1 or 2, wherein, The calcined kaolin is obtained by calcining kaolin ore at 600-650℃ or 800-850℃; And / or, the average particle size of the calcined kaolin is 80-160 mesh.

4. The geopolymer raw material composition according to claim 1 or 2, wherein, The activator includes inorganic strong basic compounds and organic weak basic compounds.

5. The geopolymer raw material composition according to claim 4, wherein, The inorganic strong base compound is selected from at least one of sodium hydroxide, potassium hydroxide, sodium silicate, and potassium silicate; the organic weak base compound is selected from at least one of methylamine, ethylenediamine, and triethylamine.

6. The geopolymer raw material composition according to claim 1 or 2, wherein, The co-solvent is selected from at least one of hydrochloric acid, sulfuric acid, and nitric acid.

7. The geopolymer raw material composition according to claim 1 or 2, wherein, The preparation process of the organic polymer-coated calcined kaolin includes: The organic polymer, co-solvent, and water are mixed to obtain an organic polymer solution; the organic polymer solution is mixed with the calcined kaolin, and then post-processed to obtain calcined kaolin coated with organic polymer.

8. The geopolymer raw material composition according to claim 7, wherein, In the organic polymer solution, the content of the organic polymer is 0.5-0.8 wt%; And / or, the amount of the co-solvent results in a pH of 4-6 for the organic polymer solution; And / or, the post-processing includes drying and crushing.

9. A geopolymer precursor slurry, characterized in that, The geopolymer precursor slurry comprises: water, organic polymer-coated calcined kaolin, and an activator; The activator is 8.9-69.7 parts by weight and the water is 50-100 parts by weight relative to 100 parts by weight of the organic polymer-coated calcined kaolin. The organic polymer-coated calcined kaolin is obtained by coating the surface of calcined kaolin with an organic polymer in the presence of a cosolvent; the organic polymer is chitosan and / or polyvinylpyrrolidone.

10. The geopolymer precursor slurry according to claim 9, wherein, The organic polymer is 0.4-1.6 parts by weight and the activator is 9-70 parts by weight relative to 100 parts by weight of the calcined kaolin.

11. The geopolymer precursor slurry according to claim 9 or 10, wherein, The organic polymer is 0.8-1.2 parts by weight and the activator is 35-50 parts by weight relative to 100 parts by weight of the calcined kaolin.

12. The geopolymer precursor slurry according to claim 9 or 10, wherein, The calcined kaolin is obtained by calcining kaolin ore at 600-650℃ or 800-850℃; And / or, the average particle size of the calcined kaolin is 80-160 mesh.

13. The geopolymer precursor slurry according to claim 9 or 10, wherein, The activator includes inorganic strong basic compounds and organic weak basic compounds.

14. The geopolymer precursor slurry according to claim 13, wherein, The inorganic strong base compound is selected from at least one of sodium hydroxide, potassium hydroxide, sodium silicate, and potassium silicate; the organic weak base compound is selected from at least one of methylamine, ethylenediamine, and triethylamine.

15. The geopolymer precursor slurry according to claim 9 or 10, wherein, The co-solvent is selected from at least one of hydrochloric acid, sulfuric acid, and nitric acid.

16. The geopolymer precursor slurry according to claim 9 or 10, wherein the preparation process of the organic polymer-coated calcined kaolin comprises: The organic polymer, co-solvent, and water are mixed to obtain an organic polymer solution; The organic polymer solution is mixed with the calcined kaolin, and then post-processed to obtain calcined kaolin coated with organic polymer.

17. The geopolymer precursor slurry according to claim 16, wherein, In the organic polymer solution, the content of the organic polymer is 0.5-0.8 wt%; And / or, the amount of the co-solvent results in a pH of 4-6 for the organic polymer solution; And / or, the post-processing includes drying and crushing.

18. The geopolymer precursor slurry according to claim 9 or 10, wherein, The geopolymer precursor slurry has a curing time of 120-480 min at 80-120℃, a fluidity of not less than 18 cm, a compressive strength of greater than 7 MPa after 1 day of curing, and a compressive strength of greater than 14 MPa after 3 days of curing.

19. The application of the geopolymer precursor slurry according to any one of claims 9-18 in high-temperature cementing.

20. A method for high-temperature cementing, wherein, The method includes: injecting the geopolymer precursor slurry according to any one of claims 9-18 downhole, obtaining the geopolymer after solidification, and using the geopolymer for cementing; Curing conditions include: temperature of 80-120℃ and pressure of 30-70MPa.

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