Hydrated calcium silicate / gelatin grafted sulfonated aldehyde ketone nanocrystal seed early strength agent for deepwater / ultra-deepwater low temperature cementing and preparation thereof

Abstract

The application discloses a hydrated calcium silicate / gelatin grafted sulfonated aldehyde ketone nano-crystal seed early strength agent for deep water / ultra-deep water low-temperature cementing and a preparation method thereof. The preparation method comprises the following steps: synthesizing gelatin grafted sulfonated aldehyde ketone polycondensate; and preparing the hydrated calcium silicate / gelatin grafted sulfonated aldehyde ketone nano-crystal seed early strength agent by taking the gelatin grafted sulfonated aldehyde ketone polycondensate as a dispersed phase through a precipitation method. The structure formula of the gelatin grafted sulfonated aldehyde ketone polycondensate is shown in the description. The hydrated calcium silicate / sulfonated aldehyde ketone nano-composite crystal seed early strength agent for oil well cement provided by the application has an application temperature range of 2-60 DEG C, and has obvious early strength effect when the addition amount in the cement slurry is 0.5-4.0% of the mass fraction of cement, and the improvement of the late hydration strength is obviously higher than that of the existing ordinary nano-hydrated calcium silicate crystal seed material.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of deep water / ultra-deep water low temperature cementing hydrated calcium silicate / gelatin grafting sulfonated aldehyde ketone nanocrystal seed early strength agent and its preparation method, belong to oil field chemical agent and oil and gas well cementing field.This nano composite crystal seed early strength agent can be used in deep water / ultra-deep water oil and gas cementing to adjust the hydration rate of oil well cement, improve the early strength of cement stone, optimize the microstructure of cement stone, etc., especially suitable for the surface casing low temperature cementing operation requirement of deep water / ultra-deep water, can significantly improve early strength, shorten the waiting-on-cement time, etc. BACKGROUND

[0002] Deep water refers to the sea area with water depth exceeding 500m, and water depth exceeding 1500m is called ultra-deep water. Global deep water oil and gas resources are abundant, and proven oil reserves in deep water area are nearly 10 billion m 3 of oil equivalent, and estimated unproven reserves are about 160 billion m 3 of oil equivalent. Deep water / ultra-deep water cementing, especially surface section, often faces low temperature, shallow water-gas flow, high deep water drilling device rental cost and other unfavorable factors compared with conventional cementing, and cementing needs to consider the length of waiting-on-cement (WOC) and early strength development. The water area seabed temperature is generally about 4℃. Temperature is the most important factor affecting the performance of cement slurry and cement stone, and the hydration speed of commonly used oil well G-grade cement is very slow at 4℃, and cement strength development is very slow. In addition, low temperature also seriously affects the development of cement slurry gel strength, makes cement slurry in gel weight loss state for a long time, and increases the risk of shallow water-gas channeling.

[0003] In cementing operation, low water-cement ratio cementing program is used to improve the strength of cement stone. In order to ensure the good pumpability of the cement slurry, a dispersing agent needs to be added to adjust the rheological properties. The aliphatic hydroxyl sulfonic acid water reducing agent is an anionic surfactant prepared by condensation of acetone, formaldehyde and sulfite under alkaline condition to obtain an aliphatic high molecular chain, and by sulfonation reaction to open the carbonyl group and introduce hydrophilic sulfonic acid group. Due to the characteristics of wide source of raw materials, simple preparation conditions, low air entraining amount and no retardation, the aliphatic hydroxyl sulfonic acid water reducing agent is widely used in oil well cement slurry. After the water reducing dispersing oil well cement slurry additive, the high activity nanomaterials are also applied to the microstructure regulation and mechanical property improvement of oil well cement due to the characteristics of excellent surface effect, quantum size effect, small size effect and interface effect. The nanometer calcium silicate hydrate crystal seed has a large number of broken bonds and defects on the surface, can adsorb ions and molecules, reduce the nucleation barrier, promote the nucleation of calcium silicate hydrate, inhibit the growth of large grains, and promote the advance of hydration heat peak. In engineering application, it is proved that the nanometer calcium silicate hydrate crystal seed can refine the cement stone pore size and significantly improve the strength of cement stone at each stage, so it becomes the key material in the research of oil well cement early strength agent. However, detailed research on the calcium-silicon ratio, particle size and dispersibility of the nanometer calcium silicate hydrate crystal seed is still lacking. In engineering application, the nanometer calcium silicate hydrate crystal seed additive can only play a positive reinforcing role at a low dosage due to its own characteristics of easy agglomeration. At a high dosage, it is easy to cause agglomeration defects. Therefore, different dispersion systems are selected for different preparation methods. At present, common dispersion phases include organic materials such as citric acid, silane and polycarboxylic acid water reducing agent to improve the dispersibility of nanometer calcium silicate hydrate. However, the addition of such organic materials significantly delays hydration, which weakens or reduces the improvement of early strength, and the early strength effect of nanometer calcium silicate hydrate is weakened or eliminated. This method is not conducive to cementing under low temperature conditions, especially it cannot meet the requirement of short waiting-on-cement time for low temperature cementing of deep water surface casing. SUMMARY

[0004] The purpose of the present application is to provide a kind of deep water / ultra deep water low temperature cementing with calcium silicate hydrate / gelatin grafted sulfonated aldehyde ketone nanometer crystal seed early strength agent and its preparation method. The nanometer calcium silicate hydrate crystal seed early strength agent provided by the present application has small particle size and good dispersibility. The early strength agent has no retardation effect on cement slurry hardening, and can significantly improve the early and late strength of cement stone, and can meet the early strength requirement of deep water, ultra deep water surface casing low temperature cementing.

[0005] The nanometer calcium silicate hydrate crystal seed early strength agent provided by the present application is prepared by the following method:

[0006] 1) Synthesis of gelatin grafted sulfonated aldehyde ketone polycondensate;

[0007] a) adjusting pH of the mixture of distilled water, formaldehyde, sodium pyrosulfite and animal gelatin to 12-13, heating to 30-35℃, dropping acetone, after dropping, increasing temperature, constant temperature reflux, obtaining reaction solution containing sulfonated aldehyde ketone condensate;

[0008] b) adjusting pH of the reaction solution containing sulfonated aldehyde ketone condensate to 4-7, continuously dropping formaldehyde, animal gelatin and sulfonated aldehyde ketone condensate in the reaction solution to carry out Mannich reaction, after dropping formaldehyde, increasing temperature of the reaction solution to 90-95℃ and constant temperature refluxing for 1-2 hours, obtaining liquid gelatin grafted sulfonated aldehyde ketone condensate;

[0009] 2) preparing hydrated calcium silicate / gelatin grafted sulfonated aldehyde ketone nanocrystal early strength agent by precipitation method with gelatin grafted sulfonated aldehyde ketone condensate as dispersed phase.

[0010] In step 1) a) above, the molar ratio of distilled water: formaldehyde: sodium pyrosulfite: animal gelatin: acetone is 4.5-10: 0.3-0.6: 0.08-0.12: 0.2-0.6: 0.3-0.6;

[0011] Controlling dropping speed of acetone to make temperature of the reaction solution ≤40℃;

[0012] Increasing temperature to 55-65℃ and constant temperature refluxing for 1.5-3.0 hours;

[0013] Reaction equation is as follows:

[0014]

[0015] Molar number of formaldehyde in step 1) b) is 0.3-0.7,

[0016] Relative molecular mass of the gelatin grafted sulfonated aldehyde ketone condensate is 8000-45000, and structural formula is as follows:

[0017]

[0018] In which, left long chain is macromolecular main chain in animal gelatin molecule;

[0019] Gelatin physical and chemical properties of the gelatin grafted sulfonated aldehyde ketone condensate are as follows: jelly strength of 10℃, 12.5% glue solution is 150-250 Bloom / g, Engler viscosity of 40℃, 15% glue solution is 3.2-5.4°E, pH value is 5.7-6.8, mesh number is 8-20;

[0020] Reaction equation is as follows:

[0021]

[0022] The step 1) b) further comprises removing the methanol and other impurities in the system after the constant temperature reflux reaction by fractional distillation under reduced pressure to obtain the liquid gelatin grafted sulfonated aldehyde ketone polycondensate, wherein the mass concentration of the gelatin grafted sulfonated aldehyde ketone polycondensate is 40% (indicating that the mass concentration of the gelatin grafted sulfonated aldehyde ketone polycondensate dispersant in the liquid state is 40%);

[0023] The operation of the step 2) is that the gelatin grafted sulfonated aldehyde ketone polycondensate in the liquid gelatin grafted sulfonated aldehyde ketone polycondensate is taken as the nano-hydrated calcium silicate dispersed phase, the Ca(NO3)2 solution and the Na2SiO3 solution with the pH value of 12-13 are mixed and injected into the gelatin grafted sulfonated aldehyde ketone polycondensate, and after the mixing and injection for 2-3 hours, the stirring is continuously carried out for 50-70 minutes to obtain the hydrated calcium silicate / gelatin grafted sulfonated aldehyde ketone nano-crystal seed early strength agent.

[0024] The mass concentration of the Ca(NO3)2 solution and the Na2SiO3 solution is 80%;

[0025] The volume ratio of the gelatin grafted sulfonated aldehyde ketone polycondensate, the Ca(NO3)2 solution and the Na2SiO3 solution can be 25mL:100mL:100mL;

[0026] The operation of the step 2) is carried out in an inert atmosphere, is carried out under the heating of a water bath at 50℃, and is carried out under high-speed stirring with the rotating speed being greater than 3000r / min.

[0027] In the obtained hydrated calcium silicate / gelatin grafted sulfonated aldehyde ketone nano-crystal seed early strength agent, the nano-hydrated calcium silicate crystal seed has the calcium-silicon ratio of 1.0, the particle size distribution is 3-100nm, the median particle size is 40nm, the volume average particle size is 30nm, the gelatin grafted sulfonated aldehyde ketone polycondensate content is 4.44%, and the nano-hydrated calcium silicate content is more than 35%.

[0028] In the obtained hydrated calcium silicate / gelatin grafted sulfonated aldehyde ketone nano-crystal seed early strength agent, the gelatin grafted sulfonated aldehyde ketone is rich in the functional groups such as -COOH, and under the intercalation of the nano-hydrated calcium silicate layer, the nano-hydrated calcium silicate crystal seed has the calcium-silicon ratio of 1.0, the particle size distribution is 3-100nm, the median particle size is 40nm, the volume average particle size is 30nm, the hydrated calcium silicate / sulfonated aldehyde ketone nano-crystal seed early strength agent has the gelatin grafted sulfonated aldehyde ketone polycondensate content of 4.44% (determined by the element analysis method), and the nano-hydrated calcium silicate content is more than 35% (the product is diluted to the mass percentage concentration of 3-5%, then filtered, dried and weighed to calculate).

[0029] The operation is simple and efficient, and the synthesized product, the gelatin grafted sulfonated aldehyde ketone, has stable properties.

[0030] The application of the above-mentioned calcium silicate hydrate / gelatin graft sulfonated aldehyde ketone nanocrystal early strength agent in deep water / ultra-deep water low-temperature cementing also belongs to the protection scope of the present application.

[0031] The low temperature is 2-60℃;

[0032] The adding amount of the calcium silicate hydrate / gelatin graft sulfonated aldehyde ketone nanocrystal early strength agent in the cementing cement is 0.5-4.0% of the cement mass fraction.

[0033] The present application solves the problems existing in the prior art oil well cement early strength agent from the following aspects:

[0034] (1) By sulfonating modification of the natural polymer animal gelatin, an environment-friendly oil well cement early strength agent dispersion phase is prepared, and the synthesized dispersion phase sample has no retardation side effect at low temperature, and is particularly suitable for cementing under low temperature conditions;

[0035] (2) By optimizing the ratio of the reactants formaldehyde, sodium pyrosulfite, animal gelatin and acetone, the synthesized product has excellent dispersion performance, and still has good dispersion ability even in high salt content;

[0036] (3) The formaldehyde is divided into two batches, so that the reaction temperature is controllable and the gelation of the reactant is effectively avoided, and the sulfonation degree of the product is improved;

[0037] (4) The sodium pyrosulfite is used as a sulfonating agent, which effectively avoids the disadvantages of using sulfite as a sulfonating agent, such as small solubility and crystallization precipitation when the temperature is higher than 34.5℃, so that the solid content of the synthesized product is high (more than 40%), and the product can be directly used without concentration, thereby reducing the production cost;

[0038] (5) The nanometer calcium silicate hydrate crystal seeds are prepared in the high molecular weight sulfonated aldehyde ketone dispersion phase by a precipitation method, and an organic adsorption layer is formed on the surface of the crystal seeds, which effectively prevents the agglomeration between the nanometer particles, and improves the dispersion and stability of the early strength agent;

[0039] (6) By optimizing the selection of the calcium source and the silicon source, the reaction temperature, the pH value and the turbulent velocity of the dispersion phase in the precipitation method, the calcium-silicon ratio and the particle size of the nanometer calcium silicate hydrate crystal seeds are effectively controlled, which is beneficial to the crystal nucleus effect of the nanometer calcium silicate hydrate crystal seeds to regulate the microstructure of the cement stone;

[0040] (7) The conflict between the early strength effect of the nanometer calcium silicate hydrate crystal seeds and the retardation effect of the commonly used dispersion phase (citric acid, silane and polycarboxylic acid water reducer) is overcome, and the early strength is more obviously improved.

[0041] The hydration calcium silicate / sulfonated aldehyde ketone nanocomposite crystal seed early strength agent for oil well cement provided by the application has a use temperature range of 2-60 DEG C, and has obvious early strength effect when the addition amount in the cement slurry is 0.5-4.0% of the mass fraction of cement, and the improvement of the late hydration strength is obviously higher than that of the existing ordinary nanometer hydration calcium silicate crystal seed material. BRIEF DESCRIPTION OF DRAWINGS

[0042] Figure 1 A particle size distribution comparison chart of the hydration calcium silicate / gelatin grafted sulfonated aldehyde ketone nanocrystal early strength agent.

[0043] Figure 2 Influence of the hydration calcium silicate / sulfonated aldehyde ketone nanocomposite crystal early strength agent on the shear stress of the cement slurry.

[0044] Figure 3 Microstructure of the cement stone of the ordinary G-grade oil well cement raw slurry PC of the comparative example of the application at low temperature 20 DEG C.

[0045] Figure 4 Microstructure of the cement stone of the example 1 (Z-1) of the application at low temperature 20 DEG C. DETAILED DESCRIPTION

[0046] The application will be further described in detail below in conjunction with specific embodiments, and the examples given are only for illustrating the application, rather than limiting the scope of the application. The examples provided below can serve as a guide for further improvement by those skilled in the art, and do not constitute any limitation on the application in any way.

[0047] In the following examples, the experimental methods are conventional methods, and are carried out according to the techniques or conditions described in the literature in the art or according to the product instructions, unless otherwise specified. The materials, reagents and the like used in the following examples can be obtained from commercial channels, unless otherwise specified.

[0048] In the following examples, the performance test method of the oil well cement early strength agent is as follows:

[0049] 1. Oil well cement slurry preparation method:

[0050] The oil well cement slurry preparation method comprises the following steps: according to the standards GB / T 19139-2012 "Oil well cement test method" and GB / T 33294-2016 "Deepwater oil well cement test method", the crystal early strength agent, the fluid loss reducer, the water and the defoaming agent are poured into the stirring slurry cup of the constant speed stirrer, the G-grade oil well cement solid phase material is continuously and uniformly poured into the stirring slurry cup at a rotating speed of 4000 rmp within 15 s to mix with the liquid phase material, and then the rotating speed is adjusted to 12000 rmp, and the oil well cement slurry is prepared after stirring for 35 s.

[0051] 2. Rheological property test:

[0052] According to the performance requirements of oil well cement slurry in standard SY / T 6544-2017, the apparent viscosity of the cement slurry under different rotational speeds was determined using a ZNN-D6 six-speed rotational viscometer (Qingdao Haitongda Instrument Factory). The rheological properties of the cement slurry were measured at 300 rmp, 200 rmp, 100 rmp, 6 rmp, and 3 rmp, respectively. The flow index n and consistency coefficient K were calculated.

[0053] 3. Compressive strength test:

[0054] The compressive strength test was performed on a cylindrical mold with a diameter of 25 mm and a height of 8 mm. The cylindrical cement sample was placed on a pressure-bearing tray. The maximum protection load was set to 100 MPa. The test piece was subjected to pressure at a rate of 100 N / S until it was crushed.

[0055] Example 1, preparation of calcium silicate hydrate / gelatin grafted sulfonated aldehyde ketone nanocrystal early strength agent

[0056] I. In a four-necked reaction flask equipped with a reflux cooling device, a stirrer, a thermometer, and a dropping funnel, distilled water, formaldehyde, sodium metabisulfite, and animal gelatin were added. The molar ratio of distilled water: formaldehyde: sodium metabisulfite: animal gelatin was 6:0.35:0.08:0.5. The pH value was adjusted to 12 with sodium hydroxide solution. Then the reaction liquid was heated to 30℃. 0.3 moles of acetone were added dropwise and the dropping speed was controlled to keep the temperature of the reaction liquid ≤40℃. After the addition was completed, the temperature was raised to 60℃ and constant temperature reflux was carried out for 3 hours. The color of the reaction liquid gradually changed from yellow to orange, and then to deep red. Sulfonated aldehyde ketone polycondensate was prepared.

[0057] II. The pH value of the reaction liquid was adjusted to 6 with dilute hydrochloric acid solution. 0.6 moles of formaldehyde were added dropwise to react with the animal gelatin and sulfonated aldehyde ketone polycondensate in the reaction liquid. After the addition of formaldehyde was completed, the reaction liquid was heated to 90℃ and constant temperature reflux was carried out for 2 hours. The reaction liquid was a deep red viscous liquid. Gelatin grafted sulfonated aldehyde ketone polycondensate was prepared.

[0058] III. The methanol and other impurities in the product were removed by vacuum fractionation. The pH value was adjusted to 7 with sodium hydroxide solution. A liquid modified dispersion material, gelatin grafted sulfonated aldehyde ketone polycondensate dispersant, suitable for reducing the agglomeration of nanoscale calcium silicate hydrate, was obtained. The mass concentration of the gelatin grafted sulfonated aldehyde ketone polycondensate dispersant was 40%.

[0059] IV. Take the above 25 mL gelatin grafted sulfonated aldehyde ketone polycondensate dispersant as the nanometer hydrated calcium silicate dispersion phase, place it in a water bath at 50°C and stir at high speed (rotational speed > 3000 r / min), and introduce nitrogen into the beaker. Prepare 100 mL of Ca(NO3)2 solution with a mass concentration of 80% and Na2SO3 solution, and adjust the pH of the Ca(NO3)2 solution to 12 by adding NaOH. Use a Y-shaped microchannel to mix the Ca(NO3)2 solution and the Na2SO3 solution at the same flow rate and inject them into the gelatin grafted sulfonated aldehyde ketone polycondensate dispersant stirred at high speed. After mixing and injecting for 3 hours, continue stirring for 50 minutes to obtain a stable hydrated calcium silicate / gelatin grafted sulfonated aldehyde ketone nanocrystal early strength agent.

[0060] Comparative Example 1: Preparation of a nanometer hydrated calcium silicate crystal early strength agent

[0061] Prepare a nanometer hydrated calcium silicate composite crystal early strength agent using deionized water as the dispersion phase: Take 25 mL of deionized water in a beaker as the nanometer hydrated calcium silicate dispersion phase, place it in a water bath at 50°C and stir at high speed (rotational speed > 3000 r / min), and introduce nitrogen into the beaker. Prepare 100 mL of Ca(NO3)2 solution with a mass concentration of 80% and Na2SO3 solution, and adjust the pH of the Ca(NO3)2 solution to 12 by adding NaOH. Use a Y-shaped microchannel to mix the Ca(NO3)2 solution and the Na2SO3 solution at the same flow rate and inject them into the deionized water stirred at high speed. After mixing and injecting for 3 hours, continue stirring for 50 minutes to obtain a nanometer hydrated calcium silicate crystal early strength agent.

[0062] Comparative Example 2: Preparation of a gelatin grafted sulfonated aldehyde ketone polycondensate dispersant

[0063] I. In a four-necked reaction flask equipped with a reflux cooling device, a stirrer, a thermometer, and a dropping funnel, add distilled water, formaldehyde, sodium metabisulfite, and animal gelatin, wherein the molar ratio of distilled water: formaldehyde: sodium metabisulfite: animal gelatin is 6:0.35:0.08:0.5. Adjust the pH to 12 with sodium hydroxide solution, then heat the reaction solution to 30°C. Add 0.3 moles of acetone dropwise and control the dropping speed so that the temperature of the reaction solution is ≤40°C. After the addition is complete, increase the temperature to 60°C and maintain reflux for 3 hours. The color of the reaction solution gradually changes from yellow to orange, and then to deep red. A sulfonated aldehyde ketone polycondensate is prepared.

[0064] II. Adjust the pH of the reaction solution to 6 with dilute hydrochloric acid solution. Continue to add 0.6 moles of formaldehyde to the reaction solution to undergo Mannich reaction with the animal gelatin and sulfonated aldehyde ketone polycondensate in the reaction solution. After the addition of formaldehyde is complete, increase the temperature of the reaction solution to 90°C and maintain reflux for 2 hours. The reaction solution is a deep red viscous liquid. A gelatin grafted sulfonated aldehyde ketone polycondensate is prepared.

[0065] III. The methanol and other impurities in the product were removed by vacuum fractionation, and the pH was adjusted to 7 with sodium hydroxide solution to obtain a liquid modified dispersion material gelatin grafted sulfonated aldehyde ketone polycondensate dispersant suitable for reducing the agglomeration of nano-hydrated calcium silicate.

[0066] Preparation of low-temperature cementing slurry Z-1 using the hydrated calcium silicate / gelatin grafted sulfonated aldehyde ketone nano-crystal seed early strength agent prepared in Application Example 1

[0067] This example is to verify the effect of the hydrated calcium silicate / gelatin grafted sulfonated aldehyde ketone nano-crystal seed early strength agent on oil well cement. The cement slurry was prepared from the following raw material components by mass fraction: G-grade oil well cement 100 parts, hydrated calcium silicate / gelatin grafted sulfonated aldehyde ketone nano-crystal seed early strength agent 2 parts, fluid loss additive (polyvinyl alcohol polymer) 1 part, defoaming agent (polyether type) 1.0 part, and water 44 parts.

[0068] Preparation of low-temperature cementing slurry Z-2 using the hydrated calcium silicate / gelatin grafted sulfonated aldehyde ketone nano-crystal seed early strength agent prepared in Application Example 1

[0069] This example is to verify the effect of the hydrated calcium silicate / gelatin grafted sulfonated aldehyde ketone nano-crystal seed early strength agent on oil well cement. The cement slurry was prepared from the following raw material components by mass fraction: G-grade oil well cement 100 parts, hydrated calcium silicate / gelatin grafted sulfonated aldehyde ketone nano-crystal seed early strength agent 4 parts, fluid loss additive (polyvinyl alcohol polymer) 1 part, defoaming agent (polyether type) 1.0 part, and water 44 parts.

[0070] Preparation of low-temperature cementing slurry Z-A using the nano-hydrated calcium silicate crystal seed early strength agent prepared in Comparative Application Example 1

[0071] This example is to verify the effect of the nano-hydrated calcium silicate crystal seed early strength agent on oil well cement. The cement slurry was prepared from the following raw material components by mass fraction: G-grade oil well cement 100 parts, nano-hydrated calcium silicate early strength agent 2 parts, fluid loss additive (polyvinyl alcohol polymer) 1 part, defoaming agent (polyether type) 1.0 part, and water 44 parts.

[0072] Preparation of low-temperature cementing slurry Z-B using the gelatin grafted sulfonated aldehyde ketone polycondensate dispersant prepared in Comparative Application Example 2

[0073] This example is to verify the effect of the gelatin grafted sulfonated aldehyde ketone polycondensate dispersant on oil well cement. The cement slurry was prepared from the following raw material components by mass fraction: G-grade oil well cement 100 parts, gelatin grafted sulfonated aldehyde ketone polycondensate dispersant 2 parts, fluid loss additive (polyvinyl alcohol polymer) 1 part, defoaming agent (polyether type) 1.0 part, and water 44 parts.

[0074] Preparation of G-grade oil well cement raw slurry PC

[0075] The comparative example is a general G-grade oil well cement raw paste PC, and the cement paste is prepared from the following raw material components in parts by mass: G-grade oil well cement 100 parts, fluid loss reducer (polyvinyl alcohol-based polymer) 1 part, defoaming agent (polyether-based) 1.0 part, and water 44 parts.

[0076] Preparation of G-grade oil well cement paste PC-1

[0077] The comparative example is a comparison of the effect of sodium citrate on the nano-hydrocalcite crystal seed early strength agent, and the cement paste is prepared from the following raw material components in parts by mass: G-grade oil well cement 100 parts, nano-hydrocalcite crystal seed early strength agent (prepared in Comparative Example 1) 4 parts, sodium citrate (industrial product) 0.005 parts, fluid loss reducer (polyvinyl alcohol-based polymer) 1 part, defoaming agent (polyether-based) 1.0 part, and water 44 parts.

[0078] Preparation of G-grade oil well cement paste PC-2

[0079] The comparative example is a comparison of the effect of polycarboxylic acid water reducer on the nano-hydrocalcite crystal seed early strength agent, and the cement paste is prepared from the following raw material components in parts by mass: G-grade oil well cement 100 parts, nano-hydrocalcite crystal seed early strength agent (prepared in Comparative Example 1) 4 parts, polycarboxylic acid water reducer (industrial product) 0.005 parts, fluid loss reducer (polyvinyl alcohol-based polymer) 1 part, defoaming agent (polyether-based) 1.0 part, and water 44 parts.

[0080] Preparation of G-grade oil well cement paste PC-3

[0081] The comparative example is a comparison of the effect of silane water reducer on the nano-hydrocalcite crystal seed early strength agent, and the cement paste is prepared from the following raw material components in parts by mass: G-grade oil well cement 100 parts, nano-hydrocalcite crystal seed early strength agent (prepared in Comparative Example 1) 4 parts, silane water reducer (industrial product) 0.05 parts, fluid loss reducer (polyvinyl alcohol-based polymer) 1 part, defoaming agent (polyether-based) 1.0 part, and water 44 parts.

[0082] Test Example 1, particle size distribution of calcium silicate / gelatin grafted sulfonated aldehyde ketone nano crystal seed early strength agent

[0083] The particle size distribution of the calcium silicate / gelatin grafted sulfonated aldehyde ketone nano crystal seed early strength agent prepared in Example 1 of the present application was tested, and the particle size distribution of the nano-hydrocalcite (prepared in Comparative Example 1) under the action of the gelatin-free sulfonated aldehyde ketone polycondensate dispersion phase was compared, and the experimental results are as follows: Figure 1As shown, the present application optimizes the preparation method of nano-hydrated calcium silicate seed crystals under the action of gelatin grafted sulfonated aldehyde ketone polycondensate dispersion phase, the particle size distribution of the obtained product is in the range of 3-100 nm, the median diameter is 40 nm, the volume average particle size is 30 nm, the product property is stable, and it is easier to store; the particle size distribution range of the nano-crystal material prepared by the ordinary method is larger, the stability of the material is poorer, and it is easy to form a precipitate.

[0084] Test Example 2, Effect of Hydrated Calcium Silicate / Gelatin Grafted Sulfonated Aldehyde Ketone Nano-seed Early Strength Agent on the Rheological Properties of Cement Paste

[0085] In order to verify the effect of the high molecular dispersant introduced in the preparation method of the present application on the rheological properties of the cement slurry, Z-1, Z-2 and Z-A, Z-B, PC, PC-1, PC-2 and PC-3 were subjected to rheological property analysis, and the experimental results are shown in Table 1 and Figure 2

[0086] Compared with the rheological properties of the G-grade oil well cement raw paste PC, after the addition of the hydrated calcium silicate / gelatin grafted sulfonated aldehyde ketone nano-seed early strength agent, the flow index n of the cement slurry increases, the consistency coefficient K decreases, the flowability of the cement slurry becomes better, and with the increase of the addition amount, the flowability of the cement slurry further improves. This shows that the introduction of gelatin grafted sulfonated aldehyde ketone polycondensate as a dispersion phase not only has no effect on the rheological properties of the cement slurry, but also has a certain improvement effect, making the cement slurry flow more easily, and confirming the feasibility of the present application in engineering application.

[0087] The application comparative example 1 (labeled as Z-A) is to add the nano-hydrated calcium silicate seed early strength agent to the cement slurry, which will make the flow index n of the cement slurry decrease, the consistency coefficient K increase, the flowability of the cement slurry become worse, and lead to the difficulty of the cement slurry flow, which is not conducive to the cementing operation.

[0088] The use of sodium citrate, polycarboxylic acid water reducing agent, silane water reducing agent and nano-hydrated calcium silicate seed early strength agent (labeled as PC-1, PC-2, PC-3) can improve the thickening and poor flowability of the nano-hydrated calcium silicate seed early strength agent on the cement slurry, and make the flowability very good, but it will lead to too much dispersion of the cement slurry, easy settlement of the cement slurry body, and adverse effect on the strength of the cement slurry.

[0089] ​In summary, the calcium silicate hydrate / gelatin grafting sulfonated aldehyde ketone nanocrystal early strength agent of the present application has a certain improvement effect on the rheological property, makes the rheological property better, and eliminates the thickening side effect of the nanometer calcium silicate hydrate crystal on the cement slurry. On the other hand, it will not lead to excessive dispersion of the cement slurry, increase of the free liquid content of the cement slurry, and poor settlement stability of the cement slurry, which is not conducive to the cementing operation.

[0090] This shows that the gelatin grafting sulfonated aldehyde ketone polycondensate introduced in the present application as a dispersion phase has no adverse effect on the rheological property of the cement slurry in addition to improving the dispersibility and stability of the nanocrystal, and proves the feasibility and benefits of the present application in engineering application.

[0091] Table 1 Influence of the calcium silicate hydrate / gelatin grafting sulfonated aldehyde ketone nanocrystal early strength agent on the rheological property of the cement slurry

[0092]

[0093]

[0094] Test Example 3 Influence of the calcium silicate hydrate / gelatin grafting sulfonated aldehyde ketone nanocrystal early strength agent on the compressive strength of the cement stone

[0095] In order to verify the influence of the present application on the compressive strength of the cement stone under low and high addition amounts, experiments were carried out at 30 DEG C and 60 DEG C, respectively, and the experimental results are shown in Table 2. The calcium silicate hydrate / gelatin grafting sulfonated aldehyde ketone nanocrystal early strength agent in Z-1 and Z-2 has a significant effect on the improvement of the early compressive strength (the improvement amplitude of the compressive strength is the largest when the curing time is 1d, the improvement amplitude is the second when the curing time is 2d, and the improvement amplitude is smaller when the curing time is 7d), which is better than the neat paste experiment PC, the nanometer calcium silicate hydrate, and the combination of the nanometer calcium silicate hydrate and different water reducing dispersants.

[0096] The experimental results of Z-2 and Z-B show that the gelatin grafting sulfonated aldehyde ketone dispersion phase system selected in the present application has no hindering effect on the development of the compressive strength of the cement stone, which proves that the calcium silicate hydrate / gelatin grafting sulfonated aldehyde ketone nanocrystal early strength agent solves the problem of the reduction of the compressive strength when the nanometer calcium silicate hydrate crystal and other water reducing dispersants (citric acid, silane, and polycarboxylic acid water reducing agent) are simply mixed and used in high addition amount, and at the same time, it solves the problem of the delayed hydration of other water reducing dispersants, which eliminates the strengthening effect of the nanometer calcium silicate hydrate crystal (the compressive strength in 1d and 2d in PC-1, PC-2, and PC-3 all shows a reduction phenomenon).

[0097] Table 2 Influence of the calcium silicate hydrate / gelatin grafting sulfonated aldehyde ketone nanocrystal early strength agent on the compressive strength

[0098]

[0099] Test Example 4, Effect of Hydrated Calcium Silicate / Gelatin Grafting Sulfonated Aldehyde Ketone Nanocrystal Early Strength Agent on Microstructure of Cement Stone

[0100] Figure 3 The microstructure of the cement stone of the ordinary G-grade oil well cement raw paste PC of the present application comparative example at low temperature 20℃, Figure 4 The microstructure of the cement stone of the oil well cement raw paste (Z-1) of the present application example 1 at low temperature 20℃. By comparison, it can be seen that in the cement stone of the present application example 1, the hydrated calcium silicate / gelatin grafting sulfonated aldehyde ketone nanocrystal early strength agent promotes the hydration of the oil well cement, a large amount of fibrous hydrated calcium silicate gel is obviously generated in the hydration product, and the microstructure of the hydration product is also more dense, which fully illustrates that the hydrated calcium silicate / gelatin grafting sulfonated aldehyde ketone nanocrystal early strength agent has a better low-temperature coagulation-promoting effect and a regulating effect on the microstructure of the hydration product.

[0101] The present application has been described in detail. For those skilled in the art, the present application can be implemented in a wider range under equivalent parameters, concentrations and conditions without departing from the purpose and scope of the present application and without unnecessary experiments. Although the present application gives a special example, it should be understood that the present application can be further improved. In summary, according to the principle of the present application, the present application is intended to include any change, use or improvement of the present application, including changes made by conventional techniques known in the art, which deviates from the scope disclosed in the present application.

Claims

1. A hydrated calcium silicate / gelatin grafted sulfonated aldehyde ketone nanoseed early strength agent, characterized in that: The early strength agent has a calcium-silicon ratio of 1.0, a particle size distribution of 3-100 nm, a median particle size of 40 nm, a volume average particle size of 30 nm, a gel state structure formed by granular irregular substances, a gelatin grafted sulfonated aldehyde ketone polycondensate content of 4.44%, and a nano-hydrated calcium silicate content of more than 35%. The structural formula of the gelatin grafted sulfonated aldehyde ketone polycondensate is as follows: In the formula, the left long chain is a macromolecular main chain of animal gelatin molecules. The method for preparing the nano-hydrated calcium silicate / gelatin grafted sulfonated aldehyde ketone early strength agent comprises the following steps: 1) synthesizing a gelatin grafted sulfonated aldehyde ketone polycondensate; 2) preparing the nano-hydrated calcium silicate / gelatin grafted sulfonated aldehyde ketone early strength agent by a precipitation method with the gelatin grafted sulfonated aldehyde ketone polycondensate as a dispersed phase; The operation of step 2) is as follows: with the liquid gelatin grafted sulfonated aldehyde ketone polycondensate as the nano-hydrated calcium silicate dispersed phase, a Ca(NO3)2 solution and a Na2SiO3 solution with a pH value of 12-13 are mixed and injected into the gelatin grafted sulfonated aldehyde ketone polycondensate, and after the injection within 2-3 hours, the stirring is continued for 50-70 minutes to obtain the nano-hydrated calcium silicate / gelatin grafted sulfonated aldehyde ketone early strength agent. In the formula, the left long chain is a macromolecular main chain of animal gelatin molecules. The volume ratio of the gelatin grafted sulfonated aldehyde ketone polycondensate to the Ca(NO3)2 solution and the Na2SiO3 solution is 25 mL:100 mL:100 mL. The operation of step 2) is carried out in an inert atmosphere, under heating in a water bath at 50 ℃, and under high-speed stirring at a speed of >3000 r / min.

2. The calcium silicate hydrate / gelatin grafted sulfonated aldehyde ketone nanoseed early strength agent according to claim 1, characterized in that: The gelatin grafted sulfonated aldehyde ketone polycondensate has the following gelatin physicochemical properties: a jelly strength of 150-250 Bloom / g at 10 ℃ and 12.5% glue solution, an Engler viscosity of 3.2-5.4 ºE at 40 ℃ and 15% glue solution, a pH value of 5.7-6.8, and a mesh number of 8-20.

3. The calcium silicate hydrate / gelatin grafted sulfonated aldehyde ketone nanoseed early strength agent according to claim 1, characterized in that: Step 1) comprises the following operations: a) adjusting the pH value of a mixture of distilled water, formaldehyde, sodium metabisulfite and animal gelatin to 12-13, heating to 30-35 ℃, adding acetone dropwise, increasing the temperature after the addition is completed, and constant temperature reflux to obtain a reaction liquid containing a sulfonated aldehyde ketone polycondensate; b) adjusting the pH value of the reaction liquid containing the sulfonated aldehyde ketone polycondensate to 4-7, continuing to add formaldehyde, and causing a Mannich reaction between the animal gelatin and the sulfonated aldehyde ketone polycondensate in the reaction liquid, increasing the temperature of the reaction liquid to 90-95 ℃ after the addition of formaldehyde is completed, and constant temperature reflux for 1-2 hours to obtain a liquid gelatin grafted sulfonated aldehyde ketone polycondensate.

4. The calcium silicate hydrate / gelatin grafted sulfonated aldehyde ketone nanoseed early strength agent according to claim 3, characterized in that: In step 1) a), the molar ratio of the distilled water:formaldehyde:sodium metabisulfite:animal gelatin:acetone is 4.5-10:0.3-0.6:0.08-0.12:0.2-0.6:0.3-0.

6. The dropping speed of the acetone is controlled to make the temperature of the reaction liquid ≤40 ℃. The temperature is increased to 55-65 ℃ and constant temperature reflux is carried out for 1.5-3.0 hours.

5. The calcium silicate hydrate / gelatin grafted sulfonated aldehyde ketone nanoseed early strength agent according to claim 3, characterized in that: In step 1) b), the number of moles of formaldehyde is 0.3-0.

7. Step 1) b) further comprises the operation of removing the methanol and other impurities in the system after the constant temperature reflux reaction by fractional distillation under reduced pressure to obtain the liquid gelatin grafted sulfonated aldehyde ketone polycondensate, wherein the concentration of the gelatin grafted sulfonated aldehyde ketone polycondensate is 40%.

6. The application of the hydrated calcium silicate / gelatin grafted sulfonated aldehyde ketone nano-seed early strength agent in deep water / ultra-deep water low temperature cementing according to claim 1.

7. Use according to claim 6, characterized in that: The low temperature is 2-60℃; The addition amount of the hydrated calcium silicate / gelatin grafted sulfonated aldehyde ketone nano-seed early strength agent in the cementing cement is 0.5-4.0% of the mass fraction of the cement.

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