Deepwater cementing low-temperature seed composite early strength agent and preparation method thereof

Abstract

The application provides a deepwater cementing low-temperature crystal seed composite early strength agent and a preparation method thereof, and belongs to the technical field of concrete admixtures. The deepwater cementing low-temperature crystal seed composite early strength agent is prepared from a mixed early strength agent and C-S-H crystal seeds, wherein the mixed early strength agent is composed of inorganic early strength agents, organic early strength agents and active ash materials; according to mass percentage, the inorganic early strength agents account for 3.8-7.8% of the deepwater cementing low-temperature crystal seed composite early strength agent, the organic early strength agents account for 0.01-0.03% of the deepwater cementing low-temperature crystal seed composite early strength agent, the active ash materials account for 1-3% of the deepwater cementing low-temperature crystal seed composite early strength agent, and the rest is the C-S-H crystal seeds. The deepwater cementing low-temperature crystal seed composite early strength agent has better low-temperature early strength performance, does not contain chloride ions, has a wide material source, is non-toxic and harmless, does not pollute the environment, and has outstanding advantages in cementing in low-temperature mining areas such as high latitude and deep sea.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of concrete admixtures, and particularly relates to a deep-water well cementing low-temperature crystal seed composite early strength agent and a preparation method thereof. BACKGROUND

[0002] In the development process of marine oil and gas resources, well cementing is a key and difficult engineering. The seabed where the deep-water well cementing engineering is located is located in the region within or below the thermocline, so the temperature is very low, and the seabed temperature of deep-water sea area is about 2-6 DEG C. The extremely low temperature leads to serious reduction of oil well cement strength growth; meanwhile, the cementing property of deep-water shallow formation is poor, and the geology is soft, so water leakage is prone to occur during well cementing, and the long-term stability of cement stone and construction safety are difficult to guarantee, which poses great challenges to well cementing operation. Therefore, to guarantee the well cementing quality under deep low-temperature environment, the cement slurry should have the characteristics of appropriate density, high early strength and low fluid loss, and the improvement of early strength under low-temperature condition is particularly crucial.

[0003] In view of the problems faced by marine deep-water well cementing, the patent with publication number CN101323779A discloses a deep-water well cementing low-temperature channeling-preventing agent composed of sodium aluminate, alkali metal chloride and oxygen-containing alkaline substances, and prepares a low-temperature early strength agent capable of shortening the setting time of cement slurry and improving the early compressive strength, but the technology applies chloride substances, which may have adverse effects on the durability in later period. The patent with publication number CN101200354A discloses an early strength agent, but it contains sodium chloride, sulfate and nitrite, etc. These components not only have influence on environmental protection, but also cause harm to the body of construction personnel and affect the durability of cement slurry.

[0004] As can be seen from the foregoing, the existing technology mainly has the following problems: (1) non-silicate cement is used as well cementing cement, although it has good low-temperature early strength performance, but in offshore well cementing, it is prone to mixing with silicate cement to cause accidents due to flash setting caused by operation conditions; (2) the conventional early strength agent often has the problem of serious thickening, especially the commonly used new early strength agent containing calcium ions and nanometer materials, a large amount of dispersing agent is usually added to the cement slurry to meet the construction requirements, but the addition of the dispersing agent not only increases the cost, but also causes competitive adsorption with the setting retarder on the surface of cement particles, so that the cement slurry formula adjustment becomes complicated.

[0005] Therefore, it is necessary to study an oil well cement early strength agent with good low-temperature early strength effect and without excessive thickening. SUMMARY

[0006] To solve the above technical problems, the application provides a deep-water well cementing low-temperature crystal seed composite early strength agent and a preparation method thereof.

[0007] To achieve the above object, the present application provides the following technical solutions:

[0008] One of the technical solutions of the present application is:

[0009] A deepwater cementing low-temperature crystal seed composite early strength agent, raw materials are mixed early strength agent and C-S-H crystal seed, wherein the mixed early strength agent is composed of inorganic early strength agent, organic early strength agent and active ash material;

[0010] According to mass percentage, the inorganic early strength agent accounts for 3.8-8.2% of the deepwater cementing low-temperature crystal seed composite early strength agent, the organic early strength agent accounts for 0.01-0.03% of the deepwater cementing low-temperature crystal seed composite early strength agent, the active ash material accounts for 1-3% of the deepwater cementing low-temperature crystal seed composite early strength agent, and the rest is C-S-H crystal seed.

[0011] Further, the inorganic early strength agent is one or more of lithium carbonate, sodium metaaluminate, calcium nitrate, sodium sulfate, potassium sulfate and nano silicon dioxide; and / or,

[0012] The organic early strength agent is one or more of triethanolamine, diethanolamine, calcium formate and calcium acetate; and / or

[0013] The active ash material is one or more of sulphoaluminate cement, aluminate cement and microsilica powder.

[0014] Further, the C-S-H crystal seed is prepared by solution method using water-soluble calcium salt and water-soluble silicate.

[0015] Further, the water-soluble calcium salt is one or more of calcium nitrate, calcium formate, calcium acetate, calcium citrate, calcium hydroxide and calcium oxide; and / or

[0016] The water-soluble silicate is one or more of potassium silicate, sodium metasilicate, potassium metasilicate and water glass.

[0017] The second technical solution of the present application is:

[0018] A preparation method of the deepwater cementing low-temperature crystal seed composite early strength agent, comprising the following steps:

[0019] The inorganic early strength agent, the organic early strength agent and the active ash material are weighed according to mass percentage, and mixed uniformly to obtain the mixed early strength agent;

[0020] The water-soluble calcium salt and the water-soluble silicate are mixed after adding water respectively to obtain a mixed solution, and the pH is adjusted to alkaline, and the hydrated calcium silicate gel is prepared after water bath stirring, and is extracted, washed and vacuum dried to obtain the C-S-H crystal seed;

[0021] Mix the mixed early strength agent and C-S-H crystal seeds uniformly to obtain the deep water cementing low-temperature crystal seed composite early strength agent.

[0022] Further, the C / S ratio of the mixed water-soluble calcium salt and water-soluble silicate is 1.6-1.8.

[0023] Further, the pH of the mixed solution is adjusted to be greater than 12 by adding sodium hydroxide.

[0024] Further, the temperature of the water bath stirring is 60℃, and the time is 7d.

[0025] Further, the time of the vacuum drying is 2d.

[0026] Exemplarily, the preparation method of the deep water cementing low-temperature crystal seed composite early strength agent of the present application specifically comprises the following steps:

[0027] Sodium sulfate 1-3%, sodium aluminate 0.2-0.4%, lithium carbonate 2-4%, and nano-silicon dioxide 0.6-0.8% are weighed according to the mass percentage, and the sodium sulfate, sodium aluminate, lithium carbonate, and nano-silicon dioxide are uniformly mixed to obtain an inorganic early strength agent. Then, organic early strength agent (triethanolamine) 0.01-0.03% and active ash (aluminate cement) 1-3% are weighed according to the mass percentage, and the inorganic early strength agent, organic early strength agent, and active ash are uniformly mixed to obtain a mixed early strength agent.

[0028] The water-soluble calcium salt (calcium nitrate tetrahydrate) and the water-soluble silicate (sodium silicate nonahydrate) are respectively added to deionized water to obtain a solution with a concentration of 1 mol / L. The two solutions are sequentially added to a three-necked flask, and the solution is uniformly mixed according to C / S=1.6-1.8 to obtain a mixed solution. A 30wt.% sodium hydroxide solution is added to the mixed solution to adjust the pH of the mixed solution to be greater than 12. Then, the mixed solution is placed in a preheated 60℃ water bath box, a stirring rod is inserted, the rotation speed is set to 2000r / min, and the reaction is carried out for 7d. The pH is adjusted to be greater than 12 by periodically adding sodium hydroxide solution. After the reaction is completed, the product is filtered, washed with ethanol for 3 times, and then dried in a vacuum drying oven for 2d to obtain C-S-H crystal seeds.

[0029] The prepared mixed early strength agent and C-S-H crystal seeds are uniformly mixed to obtain a deep water cementing low-temperature crystal seed composite early strength agent.

[0030] In the preparation process of the composite early strength agent, the mass percentage of each raw material is the mass percentage of the raw material in the deep water cementing low-temperature crystal seed composite early strength agent, and the balance is the C-S-H crystal seed.

[0031] In the above preparation process, the composite early strength agent is composed of inorganic early strength agent (sodium sulfate, sodium metaaluminate, lithium carbonate and nano silicon dioxide) and organic early strength agent (triethanolamine) and active ash (aluminate cement) in proportion, wherein sodium sulfate generates calcium sulfate and sodium hydroxide with calcium hydroxide generated in the slurry, accelerates the generation speed of cement stone AFT (ettringite), the generation of sodium hydroxide improves the alkalinity of the cement slurry system, and the solubility of C3A (calcium aluminate) is positively promoted, and the generation of AFT is accelerated; sodium metaaluminate reacts with calcium sulfate to generate AFT and sodium hydroxide, and the reaction consumes a large amount of calcium sulfate, so that C3A accelerates hydration to generate more AFT, and the reaction of sodium metaaluminate in the cement slurry is a violent exothermic reaction, the heat released makes the internal temperature of the slurry rise, to a certain extent, accelerates the hydration process, thereby improving the early compressive strength of the cement stone; nano silicon dioxide has a large number of high-activity unsaturated silicon-oxygen bonds and silicon single bonds on its surface, especially in the induction stage of cement slurry hydration, it will react with the calcium hydroxide generated by the hydration of the cement slurry, and small particle C-S-H is generated on the surface of nano silicon dioxide, which provides active reaction sites for the cement hydration reaction, also known as nucleation active points, so that the energy barrier of C-S-H generation in the cement slurry system is reduced, a large amount of C-S-H is generated, and the cement hydration is accelerated; lithium carbonate will ionize in the water-containing system of the cement slurry, and the ionized Li + With small radius and strong polarization, it can accelerate the rupture of the hydration protective film formed in the hydration induction period of the cement slurry, so that the cement hydration acceleration period is advanced, thereby improving the hydration capacity of C3S (tricalcium silicate) and C2S (dicalcium silicate) and improving the early strength. 2+ And Fe 3+ Form a complex, hinder the formation of an impermeable film on the surface of the hydrated particles in the induction period, thereby accelerating the hydration of C3A and C4AF (aluminum tetra calcium), generating a large amount of AFT, and improving the early strength; a large amount of Ca 2+ And Na + As an alkali activator, dissociate the glass structure of the active ash, so that Al 3+ , etc. in the glass body enter the solution, accelerate the generation of new phases, i.e. hydrated calcium silicate gel and hydrated calcium aluminate gel, and shorten the hardening time of the cement stone.

[0032] Compared with the prior art, the present application has the following advantages and technical effects:

[0033] (1) The low-temperature crystal seed composite early strength agent for deepwater cementing of the present application has better low-temperature early strength performance than the prior art, can be used with coal ash floating beads and other lightening agents, can be used to prepare cement slurries with different densities, has no special requirements for water quality, has no obvious thickening, does not contain chloride ions, has a wide source of materials, is non-toxic and harmless, and has no pollution to the environment.

[0034] (2) The low-temperature crystal seed composite early strength agent for deepwater cementing can greatly reduce the cement hydration reaction rate, promote the crystallization and nucleation of hydrated calcium silicate, and significantly improve the early strength of the cement stone, thereby having outstanding advantages in cementing in low-temperature mining areas such as high latitude and deep sea. DETAILED DESCRIPTION

[0035] Various exemplary embodiments of the present application will now be described in detail, which should be considered to be illustrative of certain aspects, features and embodiments of the present application and not restrictive of the present application.

[0036] It should be understood that the terms used in the present application merely describe particular embodiments and are not intended to limit the present application. In addition, for numerical ranges in the present application, it should be understood that each intermediate value between the upper limit and the lower limit of the range is also specifically disclosed. Each smaller range within any stated range or within any stated intermediate value is also encompassed within the scope of the present application. The upper limit and the lower limit of these smaller ranges can be included or excluded independently.

[0037] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present application, preferred methods and materials are described. All documents mentioned herein are incorporated by reference to disclose and describe in full the methods and / or materials which are described therein. In case of conflict, the content of the present specification will control.

[0038] Various modifications and changes can be made to the specific embodiments of the present application described herein without departing from the scope or spirit of the application. Other embodiments of the application will be apparent to those of ordinary skill in the art from the description and examples presented herein. The description and examples are illustrative of the application and are not intended to limit the scope of the application.

[0039] As used herein, the terms "comprise", "comprising", "include", "including", "have", "having" and the like are open-ended terms that are intended to mean "including but not limited to".

[0040] The embodiment of the present application provides a low-temperature crystal seed composite early strength agent for deepwater cementing, which is composed of a mixed early strength agent and C-S-H crystal seeds, wherein the mixed early strength agent is composed of an inorganic early strength agent, an organic early strength agent and active ash.

[0041] In the low-temperature crystal seed composite early strength agent for deepwater cementing, the inorganic early strength agent accounts for 3.8-8.2% by mass, the organic early strength agent accounts for 0.01-0.03% by mass, the active ash accounts for 1-3% by mass, and the rest is C-S-H crystal seeds.

[0042] In the preferred embodiment of the present application, the inorganic early strength agent is one or more of lithium carbonate, sodium metaaluminate, calcium nitrate, sodium sulfate, potassium sulfate and nano-silica, preferably a mixture of sodium sulfate, sodium metaaluminate, lithium carbonate and nano-silica.

[0043] In the preferred embodiment of the present application, the organic early strength agent is one or more of triethanolamine, diethanolamine, calcium formate and calcium acetate, preferably triethanolamine.

[0044] In the preferred embodiment of the present application, the active ash is one or more of sulphoaluminate cement, aluminate cement and micro-silica powder, preferably aluminate cement.

[0045] In the preferred embodiment of the present application, the C-S-H seed is prepared by a solution method using a water-soluble calcium salt and a water-soluble silicate, wherein the water-soluble calcium salt is one or more of calcium nitrate, calcium formate, calcium acetate, calcium citrate, calcium hydroxide and calcium oxide, preferably calcium nitrate tetrahydrate, and the water-soluble silicate is one or more of sodium silicate, potassium silicate, sodium metasilicate, potassium metasilicate and water glass, preferably sodium silicate nonahydrate.

[0046] The embodiment of the present application also proposes a preparation method of the deepwater cementing low-temperature seed composite early strength agent, comprising the following steps:

[0047] The inorganic early strength agent, the organic early strength agent and the active ash are weighed according to the mass percentage, mixed uniformly to obtain a mixed early strength agent;

[0048] The water-soluble calcium salt and the water-soluble silicate are mixed after being added with water respectively to obtain a mixed solution, and the pH is adjusted to alkaline, and a calcium silicate hydrate gel is prepared after water bath stirring, and is extracted, washed and vacuum dried to obtain the C-S-H seed;

[0049] The mixed early strength agent and the C-S-H seed are mixed uniformly to obtain the deepwater cementing low-temperature seed composite early strength agent.

[0050] In the preferred embodiment of the present application, the C / S ratio of the mixed water-soluble calcium salt and water-soluble silicate is 1.6-1.8, and it is pointed out that the C / S ratio of 1.6-1.8 refers to the molar ratio of calcium oxide to silicon dioxide formed in the mixed solution is 1.6-1.8:1.

[0051] In the preferred embodiment of the present application, the pH of the mixed solution is adjusted to >12 by adding sodium hydroxide.

[0052] In the preferred embodiment of the present application, the temperature of the water bath stirring is 60℃, and the time is 7d.

[0053] In the preferred embodiment of the present application, the time of the vacuum drying is 2d, and the temperature is 60℃.

[0054] The mass percentage of each raw material in the preparation process of the mixed early strength agent is the mass percentage of the raw material in the deepwater well cementing low-temperature seed composite early strength agent, and the balance is C-S-H seed.

[0055] The raw materials used in the embodiment of the application are commercially available.

[0056] The technical solutions of the application are further described below through examples.

[0057] Example 1

[0058] A preparation method of a deepwater well cementing low-temperature seed composite early strength agent, comprising the following steps:

[0059] Sodium sulfate 1%, sodium metaaluminate 0.2%, lithium carbonate 2% and nano-silicon dioxide (particle size 10-100 nm, the same below) 0.6% are weighed according to the mass percentage, and the sodium sulfate, sodium metaaluminate, lithium carbonate and nano-silicon dioxide are uniformly mixed to obtain an inorganic early strength agent. Then, organic early strength agent (triethanolamine) 0.01% and active ash (aluminate cement) 1% are weighed according to the mass percentage, and the inorganic early strength agent, organic early strength agent and active ash are uniformly mixed to obtain a mixed early strength agent.

[0060] Water-soluble calcium salt (calcium nitrate tetrahydrate) and water-soluble silicate (sodium silicate nonahydrate) are added to deionized water respectively to obtain a solution with a concentration of 1 mol / L for standby. The two solutions are sequentially added to a three-necked flask, and the solutions are uniformly mixed according to C / S=1.6 (i.e. the molar ratio of calcium oxide to silicon dioxide in the mixed solution is 1.6:1), to obtain a mixed solution. A 30wt.% sodium hydroxide solution is added to the mixed solution to adjust the pH of the mixed solution to >12. Then, the mixed solution is placed in a 60℃ water bath box preheated in advance, a stirring rod is inserted, the stirring speed is set to 2000r / min, and the reaction is carried out for 7d. The pH is adjusted to >12 by periodically adding sodium hydroxide solution. After the reaction is completed, the product is filtered, washed with ethanol for 3 times, and then dried in a vacuum drying oven for 2d to obtain C-S-H seed.

[0061] The prepared mixed early strength agent and C-S-H seed are uniformly mixed (i.e. according to the total mass fraction of the raw materials being 100%, sodium sulfate 1%, sodium metaaluminate 0.2%, lithium carbonate 2% and nano-silicon dioxide 0.6%, organic early strength agent 0.01%, active ash 1%, and the balance is C-S-H seed), to obtain a deepwater well cementing low-temperature seed composite early strength agent.

[0062] Example 2

[0063] A preparation method of a deepwater well cementing low-temperature seed composite early strength agent, comprising the following steps:

[0064] Sodium sulfate 1%, sodium aluminate 0.3%, lithium carbonate 3% and nano-silica (particle size 10-100 nm) 0.7% are weighed according to the mass percentage, and the sodium sulfate, sodium aluminate, lithium carbonate and nano-silica are uniformly mixed to obtain an inorganic early strength agent. Then, organic early strength agent (triethanolamine) 0.02% and active ash (aluminate cement) 2% are weighed according to the mass percentage, and the inorganic early strength agent, organic early strength agent and active ash are uniformly mixed to obtain a mixed early strength agent.

[0065] Water-soluble calcium salt (calcium nitrate tetrahydrate) and water-soluble silicate (sodium silicate nonahydrate) are added to deionized water to obtain a solution with a concentration of 1 mol / L. The two solutions are sequentially added to a three-necked flask, and the solution is uniformly mixed according to C / S = 1.6. A 30wt.% sodium hydroxide solution is added to the mixed solution to adjust the pH of the mixed solution to > 12. The mixed solution is then placed in a preheated 60°C water bath, a stirring rod is inserted, and the stirring speed is set to 2000 r / min. The reaction is carried out for 7 days, and sodium hydroxide solution is added periodically to adjust the pH to > 12. After the reaction is completed, the product is filtered and washed with ethanol three times. The washed product is dried in a vacuum drying oven for 2 days to obtain C-S-H crystal seeds.

[0066] The prepared mixed early strength agent and C-S-H crystal seeds are uniformly mixed to obtain a deepwater cementing low-temperature crystal seed composite early strength agent.

[0067] Example 3

[0068] A preparation method of a deepwater cementing low-temperature crystal seed composite early strength agent, comprising the following steps:

[0069] Sodium sulfate 1%, sodium aluminate 0.4%, lithium carbonate 2% and nano-silica 0.8% are weighed according to the mass percentage, and the sodium sulfate, sodium aluminate, lithium carbonate and nano-silica are uniformly mixed to obtain an inorganic early strength agent. Then, organic early strength agent (triethanolamine) 0.03% and active ash (aluminate cement) 3% are weighed according to the mass percentage, and the inorganic early strength agent, organic early strength agent and active ash are uniformly mixed to obtain a mixed early strength agent.

[0070] The water-soluble calcium salt (calcium nitrate tetrahydrate) and the water-soluble silicate (sodium silicate nonahydrate) are respectively added to deionized water to obtain a solution with a concentration of 1 mol / L, the two solutions are sequentially added to a three-necked flask, the solution is uniformly mixed according to C / S = 1.6-1.8, a mixed solution is obtained, a 30wt.% sodium hydroxide solution is added to the mixed solution to adjust the pH of the mixed solution to be greater than 12, then the mixed solution is placed in a 60℃ water bath box preheated in advance, a stirring rod is inserted, the rotation speed is set to 2000r / min, the reaction is carried out for 7d, the pH is adjusted to be greater than 12 by periodically adding a sodium hydroxide solution, after the reaction is completed, the product is filtered, the filtered product is repeatedly washed with ethanol for 3 times, the washed and filtered product is placed in a vacuum drying box and dried for 2d, and a C-S-H crystal seed is obtained.

[0071] The prepared mixed early strength agent and the C-S-H crystal seed are uniformly mixed to obtain a deepwater cementing low-temperature crystal seed composite early strength agent.

[0072] Example 4

[0073] A preparation method of a deepwater cementing low-temperature crystal seed composite early strength agent, comprising the following steps:

[0074] Sodium sulfate 2%, sodium metaaluminate 0.2%, lithium carbonate 2% and nano silicon dioxide 0.6% are weighed according to the mass percentage, and the sodium sulfate, the sodium metaaluminate, the lithium carbonate and the nano silicon dioxide are uniformly mixed to obtain an inorganic early strength agent, then an organic early strength agent (triethanolamine) 0.01% and active ash (aluminous cement) 1% are weighed according to the mass percentage, and the inorganic early strength agent, the organic early strength agent and the active ash are uniformly mixed to obtain a mixed early strength agent.

[0075] The water-soluble calcium salt (calcium nitrate tetrahydrate) and the water-soluble silicate (sodium silicate nonahydrate) are respectively added to deionized water to obtain a solution with a concentration of 1 mol / L, the two solutions are sequentially added to a three-necked flask, the solution is uniformly mixed according to C / S = 1.6-1.8, a mixed solution is obtained, a 30wt.% sodium hydroxide solution is added to the mixed solution to adjust the pH of the mixed solution to be greater than 12, then the mixed solution is placed in a 60℃ water bath box preheated in advance, a stirring rod is inserted, the rotation speed is set to 2000r / min, the reaction is carried out for 7d, the pH is adjusted to be greater than 12 by periodically adding a sodium hydroxide solution, after the reaction is completed, the product is filtered, the filtered product is repeatedly washed with ethanol for 3 times, the washed and filtered product is placed in a vacuum drying box and dried for 2d, and a C-S-H crystal seed is obtained.

[0076] The prepared mixed early strength agent and the C-S-H crystal seed are uniformly mixed to obtain a deepwater cementing low-temperature crystal seed composite early strength agent.

[0077] Example 5

[0078] A preparation method of a deepwater cementing low-temperature crystal seed composite early strength agent, comprising the following steps:

[0079] Sodium sulfate 2%, sodium metaaluminate 0.3%, lithium carbonate 3% and nano-silica 0.7% are weighed according to the mass percentage, and the sodium sulfate, sodium metaaluminate, lithium carbonate and nano-silica are uniformly mixed to obtain an inorganic early strength agent. Then, organic early strength agent (triethanolamine) 0.02% and active ash (aluminate cement) 2% are weighed according to the mass percentage, and the inorganic early strength agent, organic early strength agent and active ash are uniformly mixed to obtain a mixed early strength agent.

[0080] Water-soluble calcium salt (calcium nitrate tetrahydrate) and water-soluble silicate (sodium silicate nonahydrate) are respectively added to deionized water to obtain a solution with a concentration of 1 mol / L. The two solutions are sequentially added to a three-necked flask, and the solution is uniformly mixed according to C / S = 1.7. A 30wt.% sodium hydroxide solution is added to the mixed solution to adjust the pH of the mixed solution to > 12. Then, the mixed solution is placed in a preheated 60℃ water bath box, a stirring rod is inserted, the rotation speed is set to 2000r / min, and the reaction is carried out for 7d. Periodically, sodium hydroxide solution is added to adjust the pH to > 12. After the reaction is completed, the product is filtered, washed with ethanol three times, and then dried in a vacuum drying oven for 2d to obtain C-S-H crystal seeds.

[0081] The prepared mixed early strength agent and C-S-H crystal seeds are uniformly mixed to obtain a deepwater cementing low-temperature crystal seed composite early strength agent.

[0082] Example 6

[0083] A preparation method of a deepwater cementing low-temperature crystal seed composite early strength agent, comprising the following steps:

[0084] Sodium sulfate 2%, sodium metaaluminate 0.4%, lithium carbonate 4% and nano-silica 0.8% are weighed according to the mass percentage, and the sodium sulfate, sodium metaaluminate, lithium carbonate and nano-silica are uniformly mixed to obtain an inorganic early strength agent. Then, organic early strength agent (triethanolamine) 0.03% and active ash (aluminate cement) 3% are weighed according to the mass percentage, and the inorganic early strength agent, organic early strength agent and active ash are uniformly mixed to obtain a mixed early strength agent.

[0085] The water-soluble calcium salt (calcium nitrate tetrahydrate) and the water-soluble silicate (sodium silicate nonahydrate) are respectively added to deionized water to obtain a solution with a concentration of 1 mol / L, the two solutions are sequentially added to a three-necked flask, the solution is uniformly mixed according to C / S = 1.7, a mixed solution is obtained, a 30wt.% sodium hydroxide solution is added to the mixed solution to adjust the pH of the mixed solution to be greater than 12, then the mixed solution is placed in a 60℃ water bath box preheated in advance, a stirring rod is inserted, the rotation speed is set to 2000r / min, the reaction is carried out for 7d, the pH is adjusted to be greater than 12 by periodically adding a sodium hydroxide solution, after the reaction is completed, the product is filtered, the filtered product is repeatedly washed with ethanol for 3 times, the washed and filtered product is placed in a vacuum drying box and dried for 2d, and a C-S-H crystal seed is obtained;

[0086] The prepared mixed early strength agent and the C-S-H crystal seed are uniformly mixed to obtain a deepwater cementing low-temperature crystal seed composite early strength agent.

[0087] Example 7

[0088] A preparation method of a deepwater cementing low-temperature crystal seed composite early strength agent, comprising the following steps:

[0089] Sodium sulfate 3%, sodium metaaluminate 0.2%, lithium carbonate 2% and nano silicon dioxide 0.6% are weighed according to the mass percentage, and the sodium sulfate, the sodium metaaluminate, the lithium carbonate and the nano silicon dioxide are uniformly mixed to obtain an inorganic early strength agent, then an organic early strength agent (triethanolamine) 0.01% and active ash (aluminates cement) 1% are weighed according to the mass percentage, and the inorganic early strength agent, the organic early strength agent and the active ash are uniformly mixed to obtain a mixed early strength agent;

[0090] The water-soluble calcium salt (calcium nitrate tetrahydrate) and the water-soluble silicate (sodium silicate nonahydrate) are respectively added to deionized water to obtain a solution with a concentration of 1 mol / L, the two solutions are sequentially added to a three-necked flask, the solution is uniformly mixed according to C / S = 1.7, a mixed solution is obtained, a 30wt.% sodium hydroxide solution is added to the mixed solution to adjust the pH of the mixed solution to be greater than 12, then the mixed solution is placed in a 60℃ water bath box preheated in advance, a stirring rod is inserted, the rotation speed is set to 2000r / min, the reaction is carried out for 7d, the pH is adjusted to be greater than 12 by periodically adding a sodium hydroxide solution, after the reaction is completed, the product is filtered, the filtered product is repeatedly washed with ethanol for 3 times, the washed and filtered product is placed in a vacuum drying box and dried for 2d, and a C-S-H crystal seed is obtained;

[0091] The prepared mixed early strength agent and the C-S-H crystal seed are uniformly mixed to obtain a deepwater cementing low-temperature crystal seed composite early strength agent.

[0092] Example 8

[0093] A preparation method of a deepwater cementing low-temperature crystal seed composite early strength agent, comprising the following steps:

[0094] Sodium sulfate 3%, sodium metaaluminate 0.3%, lithium carbonate 3% and nano-silica 0.7% are weighed according to the mass percentage, and the sodium sulfate, sodium metaaluminate, lithium carbonate and nano-silica are uniformly mixed to obtain an inorganic early strength agent. Then, organic early strength agent (triethanolamine) 0.02% and active ash (aluminate cement) 1% are weighed according to the mass percentage, and the inorganic early strength agent, organic early strength agent and active ash are uniformly mixed to obtain a mixed early strength agent.

[0095] Water-soluble calcium salt (calcium nitrate tetrahydrate) and water-soluble silicate (sodium silicate nonahydrate) are added to deionized water to obtain a solution with a concentration of 1 mol / L. The two solutions are sequentially added to a three-necked flask, and the solution is uniformly mixed according to C / S = 1.8 to obtain a mixed solution. A 30wt.% sodium hydroxide solution is added to the mixed solution to adjust the pH of the mixed solution to > 12. Then, the mixed solution is placed in a preheated 60°C water bath, a stirring rod is inserted, the stirring speed is set to 2000 r / min, and the reaction is carried out for 7 days. Periodically, sodium hydroxide solution is added to adjust the pH to > 12. After the reaction is completed, the product is filtered, washed with ethanol three times, and then dried in a vacuum drying oven for 2 days to obtain C-S-H crystal seeds.

[0096] The mixed early strength agent and the C-S-H crystal seeds are uniformly mixed to obtain a deepwater cementing low-temperature crystal seed composite early strength agent.

[0097] Example 9

[0098] A preparation method of a deepwater cementing low-temperature crystal seed composite early strength agent, comprising the following steps:

[0099] Sodium sulfate 3%, sodium metaaluminate 0.4%, lithium carbonate 4% and nano-silica 0.8% are weighed according to the mass percentage, and the sodium sulfate, sodium metaaluminate, lithium carbonate and nano-silica are uniformly mixed to obtain an inorganic early strength agent. Then, organic early strength agent (triethanolamine) 0.03% and active ash (aluminate cement) 1% are weighed according to the mass percentage, and the inorganic early strength agent, organic early strength agent and active ash are uniformly mixed to obtain a mixed early strength agent.

[0100] The water-soluble calcium salt (calcium nitrate tetrahydrate) and the water-soluble silicate (sodium silicate nonahydrate) are respectively added to deionized water to obtain a solution with a concentration of 1 mol / L. The two solutions are sequentially added to a three-necked flask, and the solution is uniformly mixed according to C / S = 1.8 to obtain a mixed solution. A 30wt.% sodium hydroxide solution is added to the mixed solution to adjust the pH of the mixed solution to > 12. Then, the mixed solution is placed in a 60℃ water bath box preheated in advance, a stirring rod is inserted, and the rotation speed is set to 2000r / min. The reaction is carried out for 7d, and the pH is adjusted to > 12 by periodically adding a sodium hydroxide solution. After the reaction is completed, the product is filtered, washed with ethanol repeatedly for 3 times, and then dried in a vacuum drying box for 2d to obtain C-S-H crystal seeds.

[0101] The prepared mixed early strength agent and C-S-H crystal seeds are uniformly mixed to obtain a deepwater cementing low-temperature crystal seed composite early strength agent.

[0102] Comparative Example 1

[0103] Sodium sulfate 3 parts, sodium metaaluminate 0.4 parts, lithium carbonate 4 parts, and nano-silicon dioxide 0.8 parts are weighed according to the mass fraction, and uniformly mixed to obtain an inorganic early strength agent. Then, 0.03 parts of an organic early strength agent (triethanolamine) and 1 part of active ash (aluminate cement) are weighed, and uniformly mixed to obtain a mixed early strength agent.

[0104] Comparative Example 2

[0105] The water-soluble calcium salt (calcium nitrate tetrahydrate) and the water-soluble silicate (sodium silicate nonahydrate) are respectively added to deionized water to obtain a solution with a concentration of 1 mol / L. The two solutions are sequentially added to a three-necked flask, and the solution is uniformly mixed according to C / S = 1.8 to obtain a mixed solution. A 30wt.% sodium hydroxide solution is added to the mixed solution to adjust the pH of the mixed solution to > 12. Then, the mixed solution is placed in a 60℃ water bath box preheated in advance, a stirring rod is inserted, and the rotation speed is set to 2000r / min. The reaction is carried out for 7d, and the pH is adjusted to > 12 by periodically adding a sodium hydroxide solution. After the reaction is completed, the product is filtered, washed with ethanol repeatedly for 3 times, and then dried in a vacuum drying box for 2d to obtain C-S-H crystal seeds, which are used as an early strength agent.

[0106] Comparative Example 3

[0107] Commercially available low-temperature early strength agent (purchased from Toda (Shandong) New Material Science and Technology Industrial Group Co., Ltd., TD-ZQJ77 type).

[0108] Comparative Example 4

[0109] The difference between the embodiment 9 and the comparative example 1 is that the preparation method of the mixed early strength agent is different, and the addition of the active ash material is omitted, and the specific process is as follows:

[0110] The sodium sulfate, the sodium metaaluminate, the lithium carbonate and the nano silicon dioxide are mixed uniformly to obtain the inorganic early strength agent, then the active ash material (aluminate cement) is weighed according to the mass percentage, and the inorganic early strength agent and the active ash material are mixed uniformly to obtain the mixed early strength agent.

[0111] The remaining steps are consistent with those of the embodiment 9.

[0112] Comparative example 5

[0113] The difference between the embodiment 9 and the comparative example 1 is that the preparation method of the mixed early strength agent is different, and the addition of the active ash material is omitted, and the specific process is as follows:

[0114] The sodium sulfate, the sodium metaaluminate, the lithium carbonate and the nano silicon dioxide are mixed uniformly to obtain the inorganic early strength agent, then the active ash material (aluminate cement) is weighed according to the mass percentage, and the inorganic early strength agent and the active ash material are mixed uniformly to obtain the mixed early strength agent.

[0115] The remaining steps are consistent with those of the embodiment 9.

[0116] Comparative example 6

[0117] The difference between the embodiment 9 and the comparative example 1 is that the preparation method of the mixed early strength agent is different, and the addition of the active ash material is omitted, and the specific process is as follows:

[0118] The sodium sulfate, the sodium metaaluminate, the lithium carbonate and the nano silicon dioxide are mixed uniformly to obtain the inorganic early strength agent, then the active ash material (aluminate cement) is weighed according to the mass percentage, and the inorganic early strength agent and the active ash material are mixed uniformly to obtain the mixed early strength agent.

[0119] The remaining steps are consistent with those of the embodiment 9.

[0120] The prepared mixed early strength agent and the C-S-H crystal seed are mixed uniformly to obtain the deepwater well cementing low-temperature crystal seed composite early strength agent.

[0121] Performance test

[0122] The deepwater well cementing low-temperature crystal seed composite early strength agent of the embodiments 1-9 and the early strength agents of the comparative examples 1-6 are subjected to performance detection, and the detection results are shown in Table 1. The detection method refers to GBT10238-2015 “Oil Well Cement” and GBT19139-2012 “Oil Well Cement Test Method”. The cement used is G-grade oil well cement, the dosage of the deepwater well cementing low-temperature crystal seed composite early strength agent is 5%, and the curing temperature is 5℃.

[0123] Table 1 Performance test results of examples and comparative examples

[0124] 8h compressive strength / MPa 12h compressive strength / MPa 24h compressive strength / MPa 36h compressive strength / MPa Comparative Example 1 3.1 7.2 11.6 14.3 Comparative Example 2 4.0 7.4 15.8 20.3 Comparative Example 3 2.9 6.5 10.0 18.7 Comparative Example 4 4.5 7.7 13.8 20.0 Comparative Example 5 4.3 7.3 12.9 19.9 Comparative Example 6 3.2 6.5 11.2 17.3 Example 1 4.9 8.1 14.3 21.5 Example 2 6.1 9.0 16.6 24.0 Example 3 6.5 9.7 17.1 28.2 Example 4 6.6 8.2 16.1 21.7 Example 5 6.9 9.5 18.8 27.3 Example 6 7.2 9.7 20.0 29.9 Example 7 6.8 9.3 17.9 28.8 Example 8 7.5 11.5 19.4 30.1 Example 9 8.6 12.2 20.0 32.2

[0125] As can be seen from Table 1, the deepwater cementing low-temperature crystal seed composite early strength agent of the present application has better low-temperature early strength performance than the prior art, can be used with a coal ash floating bead and other weight reducing agents, can be used to prepare cement slurries with different densities, has no special requirements for water quality, has no obvious thickening, contains no chloride ions, has a wide source of materials, is non-toxic and harmless, and has no pollution to the environment. The deepwater cementing low-temperature crystal seed composite early strength agent can greatly reduce the hydration reaction rate of cement, promote the nucleation of hydrated calcium silicate, and significantly improve the early strength of cement stone, and has outstanding advantages in cementing in low-temperature mining areas such as high latitude and deep sea.

[0126] Please explain the specific reasons for the performance decline of Comparative Example 1-2, Comparative Example 4-6 compared to Example 9:

[0127] In the early hydration process of the G-grade oil well cement, each component of the deepwater cementing low-temperature crystal seed composite early strength agent of Example 9 of the present application plays the following roles. Sodium sulfate reacts with calcium hydroxide generated in the slurry to generate calcium sulfate and sodium hydroxide, accelerates the generation speed of cement stone AFT (ettringite), and the generation of sodium hydroxide improves the alkalinity of the cement slurry system, which positively promotes the solubility of C3A (calcium aluminate), and accelerates the generation of AFT; sodium aluminate reacts with calcium sulfate to generate AFT and sodium hydroxide, and the reaction consumes a large amount of calcium sulfate, which accelerates the hydration of C3A and generates more AFT. At the same time, the reaction of sodium aluminate in the cement slurry is a violent exothermic reaction, and the heat released by the reaction increases the internal temperature of the slurry, to some extent, accelerates the hydration process, thereby improving the early compressive strength of the cement stone; nano silicon dioxide has a large number of high-activity unsaturated silicon-oxygen bonds and silicon single bonds on its surface, which will react with calcium hydroxide generated by the hydration of the cement slurry in the induction stage of the hydration of the cement slurry, to generate small-particle C-S-H on the surface of the nano silicon dioxide. Small-particle C-S-H provides active reaction sites for the cement hydration reaction, also known as nucleation active sites, which reduces the energy barrier for the generation of C-S-H in the cement slurry system, induces the generation of a large amount of C-S-H, and promotes the rapid hydration of the cement; lithium carbonate will ionize in the aqueous system of the cement slurry, and the ionized Li + has a small radius and strong polarization, which can accelerate the rupture of the hydration protection film formed in the hydration induction period of the cement slurry, so as to advance the acceleration period of the cement hydration, thereby improving the hydration capacity of C3S (tricalcium silicate) and C2S (dicalcium silicate), and improving the early strength. 2+ and Fe 3+The complex formation hinders the formation of impermeable film on the surface of the hydrating particles in the induction period, thus accelerating the hydration of C3A and C4AF (tetracalcium aluminate) to generate a large amount of AFT, improving the early strength; a large amount of Ca 2+ and Na + As an alkali activator, the glass structure of the active ash is dissociated, so that Al 3+ and other elements in the glass body enter the solution, accelerating the generation of new phases, i.e. calcium silicate hydrate gel and calcium aluminate hydrate gel, shortening the hardening time of the cement stone.

[0128] Comparative Examples 1-2 and 4-6 are either inorganic or organic early strength agents as single components or composite early strength agents omitting some components, and lack the synergistic effect between the components relative to Example 9, and the promotion of the early hydration process and the early strength enhancement effect of the G-grade oil well cement cannot reach the level of Example 9, so the strength is lower than that of Example 9.

[0129] The above is only a preferred specific embodiment of the present application, but the protection scope of the present application is not limited thereto, and any person skilled in the art can easily think of changes or replacements within the technical scope disclosed by the present application, which should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A low temperature seed composite early strength agent for deep water cementing, characterized in that, The raw material is a mixed early strength agent and C-S-H seeds, wherein the mixed early strength agent is composed of inorganic early strength agent, organic early strength agent and active ash material; The inorganic early strength agent accounts for 3.8-8.2% of the deep water well cementing low-temperature seed composite early strength agent by mass percentage, the organic early strength agent accounts for 0.01-0.03% of the deep water well cementing low-temperature seed composite early strength agent by mass percentage, the active ash material accounts for 1-3% of the deep water well cementing low-temperature seed composite early strength agent by mass percentage, and the rest is C-S-H seeds; The inorganic early strength agent is one or more of lithium carbonate, sodium metaaluminate, calcium nitrate, sodium sulfate, potassium sulfate and nano silicon dioxide; The organic early strength agent is one or more of triethanolamine, diethanolamine, calcium formate and calcium acetate; The active ash material is one or more of sulphoaluminate cement, aluminate cement and microsilica powder; The dosage of the deep water well cementing low-temperature seed composite early strength agent in cement is 5%.

2. The low temperature seed composite early strength agent for deep water cementing according to claim 1, characterized in that, The C-S-H seeds are prepared by using a solution method with water-soluble calcium salt and water-soluble silicate.

3. The low temperature seed composite early strength agent for deep water cementing according to claim 2, characterized in that, The water-soluble calcium salt is one or more of calcium nitrate, calcium formate, calcium acetate, calcium citrate, calcium hydroxide and calcium oxide; and / or The water-soluble silicate is one or more of potassium silicate, sodium metasilicate, potassium metasilicate and water glass.

4. A method for preparing the low temperature seed composite early strength agent for deep water cementing of any one of claims 1-3, characterized in that, The method comprises the following steps: The inorganic early strength agent, the organic early strength agent and the active ash material are weighed by mass percentage, and the mixed early strength agent is obtained after being mixed uniformly; The water-soluble calcium salt and the water-soluble silicate are mixed after being added with water respectively to obtain a mixed solution, and the pH is adjusted to alkaline, and the calcium silicate hydrate gel is prepared after water bath stirring, and is extracted, washed and vacuum dried to obtain the C-S-H seeds; The mixed early strength agent and the C-S-H seeds are mixed uniformly to obtain the deep water well cementing low-temperature seed composite early strength agent.

5. The method for preparing the low-temperature seed composite early strength agent for deepwater cementing of claim 4, characterized in that, The C / S molar ratio of the mixed water-soluble calcium salt and water-soluble silicate is 1.6-1.

8.

6. The method for preparing the low-temperature seed composite early strength agent for deepwater cementing of claim 4, characterized in that, The pH of the mixed solution is adjusted by adding sodium hydroxide.

7. The method for preparing the low temperature seed composite early strength agent for deep water cementing of claim 6, characterized in that, The pH of the mixed solution is adjusted to >12 by adding sodium hydroxide.

8. The method for preparing the low-temperature seed composite early strength agent for deepwater cementing of claim 4, characterized in that, The temperature of the water bath stirring is 60℃, and the time is 7d.

9. The method for preparing the low-temperature seed composite early strength agent for deepwater cementing of claim 4, characterized in that, The time of the vacuum drying is 2d.