Intercalation admixture for well cementation, preparation method of intercalation admixture, cement paste and application of intercalation admixture
By preparing intercalated hydrotalcite-type admixtures, the problem of slow strength development of cement slurry in long-sealing cementing with large temperature differences was solved, and the stability and strength of cement slurry were improved in different temperature ranges, making it suitable for cementing deep and ultra-deep wells.
Patent Information
- Application Number
- CN202411102261.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-08-12
- Publication Date
- 2026-02-13
AI Technical Summary
Existing retarders are prone to slow cement slurry strength development and abnormal gelation problems in long-term cementing operations with large temperature differences, which affect the safety and lifespan of oil and gas wells.
Intercalated hydrotalcite admixtures were prepared using co-precipitation and ion exchange methods. Hydroxyethylidene diphosphonic acid (HEDP) was inserted into the interlayer of hydrotalcite to form Mg/Al-HEDP-LDH, which served as a retarder for cement slurry, adjusting the hydration rate and thickening time of cement.
It improves the strength development of cement slurry in low-temperature well sections during long-sealing cementing with large temperature differences, enhances the stability and compressive strength of the cement slurry, is suitable for multiple temperature ranges, has adjustable thickening time, is simple to operate and uses readily available raw materials.
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Figure CN121517136A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of cementing admixtures for oil and gas field exploration, and particularly to an intercalation admixture for cementing, its preparation method, cement slurry including the intercalation admixture, and its application. Background Technology
[0002] With the deepening and expansion of oil and gas field exploration both domestically and internationally, the number of deep wells and wells with long cemented sections is increasing year by year. To reinforce the wellbore, ensure smooth drilling, and guarantee reasonable oil and gas production during exploration and the entire production process, it is necessary to run casing of a predetermined size into the drilled wellbore, and then inject cement slurry into the annulus between the casing and the wellbore. This operation is called cementing. Cementing is a crucial step in the drilling and completion process. During cementing, the prepared cement slurry is first injected into the annulus between the formation and the casing string. After displacing the slurry to the predetermined position, the cement hardens, thereby reinforcing the wellbore, protecting the casing, and sealing off oil, gas, and water layers. In this process, the performance of the cement slurry largely determines the safety and quality of the cementing operation.
[0003] During cementing of deep and ultra-deep wells, the cement slurry undergoes a process from low temperature to high temperature and then back to low temperature. This process involves long pumping times, high bottom-hole temperatures, long single-stage cementing sections, and large temperature differences between the top and bottom. High-temperature retarders, which span high, medium, and low temperature isotherms, are prone to problems such as slow strength development and prolonged non-setting of the cement slurry in the upper formation, known as the ultra-retarded setting phenomenon. This can result in the top cement slurry lacking strength for days or even a month, leading to interlayer sealing failure. In severe cases, this can affect subsequent oil and gas resource extraction and the lifespan of oil and gas wells.
[0004] Oil well cement hydration is a complex process, and the main function of retarders is to slow down cement hydration and prevent cement slurry under high temperature and pressure conditions from losing fluidity before being pumped to the designed well section. There are many types of oil well cement retarders, mainly including lignin sulfonates and their derivatives, carbohydrate compounds, inorganic salts, hydroxycarboxylic acids (salts), and polymers. Lignosulfonate retarders suffer from uneven composition and structure, resulting in variable performance and increased difficulty in cementing operations. Hydroxycarboxylic acid (salt) retarders exhibit strong dosage and temperature sensitivity, which increases the difficulty of adjusting the cement slurry formulation on-site and affects cement slurry performance. Polymer retarders generally have low operating temperatures, and their thickening curves are prone to "bulging." Furthermore, polymers have high-temperature dilution characteristics, leading to poor high-temperature stability of the cement slurry. Therefore, when existing retarders are applied to long-term cementing operations with large temperature differences, they are prone to slow mechanical property development and abnormal cement slurry gelation.
[0005] Therefore, there is an urgent need in this field to study a cement admixture suitable for cementing with long sealing and large temperature difference to improve the problem of slow cement strength development. Summary of the Invention
[0006] To address the above-mentioned problems, the present invention provides an intercalation admixture for cementing, a method for preparing the same, a cement slurry including the intercalation admixture, and its application.
[0007] According to one aspect of the present invention, a method for preparing a cementing intercalation admixture is provided, comprising the following steps: Step S1: Prepare intercalated hydrotalcite precursor by coprecipitation method, wherein the anion of the intercalated hydrotalcite precursor is carbonate ion; Step S2: Dissolve hydroxyethylidene diphosphonic acid in a solvent to prepare a first solution, add the intercalated hydrotalcite precursor to the first solution, adjust the pH value to completely dissolve the intercalated hydrotalcite precursor, and obtain a second solution. Step S3: Perform ion exchange on the second solution at a set temperature, cool it, and then process it to obtain the intercalation additive.
[0008] According to one embodiment of the present invention, the intercalated hydrotalcite precursor is a Mg / Al-CO3-LDH precursor.
[0009] According to one embodiment of the present invention, when preparing the intercalation admixture, the weight ratio of the Mg / Al-CO3-LDH precursor to the hydroxyethylidene diphosphonic acid is 1:1~12.
[0010] According to one embodiment of the present invention, the preparation process of the Mg / Al-CO3-LDH precursor includes the following steps: Step S1-1: Add NaOH to deionized water to prepare solution A, add Na2CO3 to deionized water to prepare solution B, and add Mg(NO3)2 and Al(NO3)3 to deionized water to prepare solution C; Step S1-2: Add solution C to solution B to obtain solution D; Step S1-3: Add solution A to solution D to prepare solution E, and adjust the pH value of solution E; Step S1-4: Perform a co-precipitation reaction on the E solution at a selected temperature; Steps S1-5: Filter, wash and dry the solution after the reaction to obtain the Mg / Al-CO3-LDH precursor.
[0011] According to one embodiment of the present invention, the components used to prepare the Mg / Al-CO3-LDH precursor are in the following weight ratio: 2-6 parts NaOH, 1-3 parts Na2CO3, 3-9 parts Mg(NO3)2, and 1-3 parts Al(NO3)3.
[0012] According to one embodiment of the present invention, in steps S1-3, the pH value of the E solution is adjusted to 9.5~10.5.
[0013] According to one embodiment of the present invention, in steps S1-4, the selected temperature is 70~90℃ and the coprecipitation reaction time is 6~10 hours.
[0014] According to one embodiment of the present invention, in step S2, the solvent is ethylene glycol.
[0015] According to one embodiment of the present invention, in step S2, the pH value is adjusted to 3.5~4.5.
[0016] According to one embodiment of the present invention, in step S3, the set temperature is 130~150℃ and the ion exchange time is 5~7 hours.
[0017] According to another aspect of the present invention, a cementing intercalation admixture is provided, the intercalation admixture being prepared by the method described in any of the above embodiments.
[0018] According to another aspect of the present invention, a cement slurry for cementing is provided, the cement slurry comprising the following components: cementing intercalation admixture as described in any of the above embodiments, cement, water, fluid loss reducing agent, dispersant, and defoamer.
[0019] The cement slurry used in cementing as described in the above embodiments is applied at a temperature of 70~110℃.
[0020] According to another aspect of the present invention, a cement slurry for cementing is provided, the cement slurry comprising the following components: cementing intercalation admixture as described in any of the above embodiments, cement, quartz sand, water, fluid loss reducing agent, dispersant, and high-temperature retarder.
[0021] The cement slurry used in cementing as described in the above embodiments is applied at a temperature of 70~180℃.
[0022] Due to the adoption of the above technical solutions, the intercalation admixture for cementing provided by this invention releases HEDP between layers under high-temperature conditions, slowing down the hydration rate of cement. The unique seeding effect and filling effect of hydrotalcite materials improve the problem of slow strength development in low-temperature well sections of existing long-sealing, large-temperature-difference cement slurry systems. This intercalation admixture is suitable for multiple temperature ranges, and the thickening time is adjustable. The intercalation admixture is synthesized using co-precipitation and ion exchange methods, which are simple to operate, have high yields, are suitable for large-scale production, and the raw materials required for synthesis are widely available and inexpensive. Furthermore, the resulting product has uniform composition and good dispersibility. Attached Figure Description
[0023] Figure 1A flowchart illustrating a method for preparing a cementing intercalation admixture according to an embodiment of the present invention; Figure 2 Thickening curves of cement with different amounts of the intercalating admixture according to the present invention at 90°C; Figure 3 The thickening curves of cement at different temperatures are obtained by combining the intercalating admixture and the high-temperature retarder according to the present invention. Detailed Implementation
[0024] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.
[0025] Layer doubled hydrates (LDHs) mainly include hydrotalcite and intercalated hydrotalcite. Hydrotalcite is an inorganic supramolecular material mainly composed of a host layer of two or more metal cations and interlayer ions. LDHs possess a series of unique and excellent properties, such as interlayer ion exchangeability, thermal stability, acid-base properties, and memory effect. Because the interlayer anions of LDHs are weakly connected to the host layer through hydrogen bonds, they are easily replaced by other anions with stronger electrostatic interactions with the host layer; therefore, LDHs exhibit ion exchange properties. Polyanionic additives can exchange with inorganic anions in the precursor and introduce them into the interlayer of hydrotalcite, thus preparing supramolecular composite materials with even better performance.
[0026] This invention first prepares a hydrotalcite precursor using a co-precipitation method, and then uses an ion exchange method to insert hydroxyethylidene diphosphonic acid (HEDP) into the interlayer of the hydrotalcite, replacing the original anions, to prepare a HEDP-intercalated hydrotalcite admixture. This admixture can be used as a cement retarder in intermediate-temperature environments and can be compounded with high-temperature retarder in high-temperature environments. When Mg / Al-HEDP-LDH is under high-temperature conditions, the HEDP in its interlayer is released, slowing down the cement hydration rate. The unique seed crystal effect and filling effect of hydrotalcite effectively improve the problem of slow strength development in low-temperature well sections of existing long-sealing, large-temperature-difference cement slurry systems, enabling it to be used as a reinforcing agent.
[0027] One aspect of the present invention provides a method for preparing an intercalation admixture for cementing. Figure 1 The overall flowchart of the method is shown. Figure 1 As shown, the method generally includes the following steps: Step S1: The intercalated hydrotalcite precursor is prepared by coprecipitation method, wherein the anion of the intercalated hydrotalcite precursor is carbonate ion; Step S2: Dissolve hydroxyethylidene diphosphonic acid in a solvent to prepare a first solution, add the intercalated hydrotalcite precursor to the first solution, adjust the pH value to completely dissolve the intercalated hydrotalcite precursor, and obtain a second solution. Step S3: Perform ion exchange on the second solution at a set temperature, cool it, and then process it to obtain the intercalation admixture.
[0028] The following provides a detailed explanation of each step of the method using examples.
[0029] In step S1, the intercalated hydrotalcite precursor is prepared by coprecipitation, wherein the anion of the intercalated hydrotalcite precursor is carbonate ion.
[0030] In some embodiments, the intercalated hydrotalcite precursor is a Mg / Al-CO3-LDH precursor, and the prepared intercalation admixture is a Mg / Al-HEDP-LDH. Optionally, other cations can be used in the intercalated hydrotalcite precursor, such as intercalated zinc-aluminum hydrotalcite or nickel-aluminum hydrotalcite. The anion in the intercalated hydrotalcite precursor is carbonate ion, so that the original carbonate ions can be replaced by HEDP intercalation in the hydrotalcite interlayer during subsequent ion exchange.
[0031] In some embodiments, when preparing the intercalation admixture Mg / Al-HEDP-LDH, the weight ratio of the Mg / Al-CO3-LDH precursor to hydroxyethylidene diphosphonic acid is 1:1~12.
[0032] The Mg / Al-CO3-LDH precursor can be prepared by the following methods: Step S1-1: Add NaOH to deionized water to prepare solution A, add Na2CO3 to deionized water to prepare solution B, and add Mg(NO3)2 and Al(NO3)3 to deionized water to prepare solution C; Step S1-2: Add solution C to solution B to obtain solution D; Step S1-3: Add solution A to solution D to prepare solution E, and adjust the pH value of solution E; Step S1-4: Perform a co-precipitation reaction on solution E at a selected temperature; Steps S1-5: Filter, wash and dry the solution after the reaction to obtain the Mg / Al-CO3-LDH precursor.
[0033] In step S1-1, the raw materials can be anhydrous Na2CO3, Mg(NO3)2·6H2O, and Al(NO3)3·9H2O. The proportions of each group are as follows: 2-6 parts NaOH, 1-3 parts Na2CO3, 3-9 parts Mg(NO3)2·6H2O, and 1-3 parts Al(NO3)3·9H2O.
[0034] In some embodiments, in steps S1-3, the pH value of solution E is adjusted to 9.5-10.5.
[0035] In some embodiments, in steps S1-4, solution E is subjected to a coprecipitation reaction at 70~90°C for 6~10 hours. After the reaction is completed, the solution is filtered, washed, and freeze-dried to obtain the Mg / Al-CO3-LDH precursor.
[0036] In step S2, hydroxyethylidene diphosphonic acid is dissolved in a solvent to prepare a first solution. The intercalated hydrotalcite precursor is added to the first solution, and the pH value is adjusted to completely dissolve the intercalated hydrotalcite precursor to obtain a second solution.
[0037] In some embodiments, the solvent is ethylene glycol, but other solvents may also be used. The weight ratio of Mg / Al-CO3-LDH precursor to hydroxyethylidene diphosphonic acid is 1:1 to 12.
[0038] In some embodiments, the pH value is adjusted to 3.5~4.5. When the pH is controlled at 3.5, the synthesized Mg / Al-HEDP-LDH has insufficient crystallinity. When the pH is controlled at 4.0, the Mg / Al-HEDP-LDH synthesized at different crystallization temperatures (130℃, 140℃, 150℃) has diffraction angles corresponding to the characteristic crystal plane (003) of 9.80°, 9.81°, and 9.75°, respectively, and corresponding interlayer spacings of 0.89nm, 0.92nm, and 0.90nm, respectively. When the pH is controlled at 4.5, the diffraction angles corresponding to the characteristic crystal plane (003) of Mg / Al-HEDP-LDH synthesized at different crystallization temperatures (130℃, 140℃, 150℃) become 7.08°, 7.34°, and 7.43°, respectively, and the interlayer spacings corresponding to them increase to 1.24nm, 1.20nm, and 1.18nm, respectively. The increase in interlayer spacing indicates that HEDP has been inserted into the interlayer of hydrotalcite.
[0039] In step S3, the second solution undergoes ion exchange at a set temperature, and after cooling, it is processed to obtain the intercalation admixture.
[0040] In some embodiments, the second solution can be heated to 130-150°C for ion exchange. After ion exchange for 5-7 hours, it is cooled, filtered, washed with deionized water and alcohol, and finally dried to obtain the intercalation admixture.
[0041] Another aspect of the present invention provides a cementing intercalation admixture. This admixture is prepared using the method described in any of the above embodiments.
[0042] This invention also provides a cement slurry for cementing, comprising the following components: a cementing intercalation admixture as described in any of the above embodiments, cement, water, a fluid loss reducing agent, a dispersant, and a defoamer. This cement slurry is suitable for medium-temperature environments, with an application temperature of 70~110℃. The intercalation admixture acts as a retarder in this cement slurry system; its interlayer HEDP is released to slow the cement hydration rate and adjust the cement thickening time.
[0043] This invention also provides a cement slurry for cementing, comprising the following components: a cementing intercalation admixture as described in any of the above embodiments, quartz sand, water, a fluid loss reducing agent, a dispersant, and a high-temperature retarder. This cement slurry is suitable for environments with large temperature differences (e.g., 70~180℃) and can be used for cementing deep and ultra-deep wells with large temperature differences. The intercalation admixture acts as a reinforcing agent in this cement slurry system, and when used in conjunction with the high-temperature retarder, it can effectively improve the problem of slow strength development in low-temperature well sections of existing long-sealing, large-temperature-difference cement slurry systems. During cement hydration, the retarder molecules between the layers of hydrotalcite material can delay cement hydration, while the unique crystal effect and filling effect of hydrotalcite material can promote the strength development of the high-temperature cement slurry system in low-temperature well sections.
[0044] The present invention will be further illustrated below with specific embodiments to enable those skilled in the art to understand the invention. However, it should be understood that the present invention is not limited to the scope of the specific embodiments. Unless otherwise specified, the experimental methods used in the following embodiments are conventional methods. Unless otherwise specified, the materials and reagents used in the following embodiments are commercially available.
[0045] Example 1 First, weigh 2 parts NaOH and add them to deionized water to prepare solution A. Then, weigh 1 part anhydrous Na₂CO₃ and add it to deionized water to prepare solution B. Next, weigh 3 parts Mg(NO₃)₂·6H₂O and 1 part Al(NO₃)₃·9H₂O and add them to deionized water to prepare solution C. Slowly add solution C to solution B to prepare solution D. Then, slowly add solution D to solution A to prepare solution E, maintaining the pH of solution E at 10.5. Finally, add solution E to a three-necked flask and allow it to crystallize at 70°C for 10 hours. After filtration, wash with deionized water until neutral and then freeze-dry to obtain the Mg / Al-CO₃-LDH precursor.
[0046] Prepare a solution by dissolving 4 parts of HEDP in 100 mL of ethylene glycol. Then, add 1 part of Mg / Al-CO3-LDH precursor to the HEDP solution and stir continuously. During stirring, add an alkaline buffer solution to adjust the pH to 4.5. Pour the solution into a three-necked flask and crystallize at 130 °C for 7 hours. After cooling, filter the solution, wash with deionized water and alcohol until neutral, and then freeze-dry to obtain the HEDP intercalated hydrotalcite additive.
[0047] Example 2 First, weigh 5 parts NaOH and add them to deionized water to prepare solution A. Then, weigh 2 parts anhydrous Na₂CO₃ and add them to deionized water to prepare solution B. Next, weigh 6 parts Mg(NO₃)₂·6H₂O and 2 parts Al(NO₃)₃·9H₂O and add them to deionized water to prepare solution C. Slowly add solution C to solution B to prepare solution D. Then, slowly add solution D to solution A to prepare solution E, maintaining the pH of solution E at 10. Finally, add solution E to a three-necked flask and allow it to crystallize at 80°C for 8 hours. After filtration, wash with deionized water until neutral and then freeze-dry to obtain the Mg / Al-CO₃-LDH precursor.
[0048] Prepare a solution by dissolving 8 parts of HEDP in 100 mL of ethylene glycol. Then, add 1 part of Mg / Al-CO3-LDH precursor to the HEDP solution and stir continuously. During stirring, add an alkaline buffer solution to adjust the pH to 4. Pour the solution into a three-necked flask and crystallize at 140 °C for 6 hours. After cooling, filter the solution, wash with deionized water and alcohol until neutral, and then freeze-dry to obtain the HEDP intercalated hydrotalcite additive.
[0049] Example 3 First, prepare solution A by weighing 6 parts NaOH and adding it to deionized water. Prepare solution B by weighing 3 parts anhydrous Na2CO3 and adding it to deionized water. Then, prepare solution C by weighing 9 parts Mg(NO3)2·6H2O and 3 parts Al(NO3)3·9H2O and adding them to deionized water. Slowly add solution C to solution B to prepare solution D. Then, slowly add solution A to solution D to prepare solution E, maintaining the pH of solution E at 9.5. Next, add solution E to a three-necked flask and crystallize at 90°C for 6 hours. After filtration, wash with deionized water until neutral and then freeze-dry to obtain the Mg / Al-CO3-LDH precursor.
[0050] Weigh 12 parts of HEDP and dissolve them in 100 mL of ethylene glycol to prepare a solution. Then weigh 2 parts of Mg / Al-CO3-LDH precursor and add them to the HEDP solution. Stir continuously, adding an alkaline buffer solution during stirring to adjust the pH to 3.5. Pour the solution into a three-necked flask and crystallize at 150 °C for 5 hours. After cooling, filter the solution, wash with deionized water and alcohol until neutral, and then freeze-dry to obtain the HEDP intercalated hydrotalcite additive.
[0051] Example 4 First, weigh 4 parts NaOH and add them to deionized water to prepare solution A. Then, weigh 2 parts anhydrous Na₂CO₃ and add them to deionized water to prepare solution B. Next, weigh 6 parts Mg(NO₃)₂·6H₂O and 2 parts Al(NO₃)₃·9H₂O and add them to deionized water to prepare solution C. Slowly add solution C to solution B to prepare solution D. Then, slowly add solution D to solution A to prepare solution E, maintaining the pH of solution E at 10.5. Finally, add solution E to a three-necked flask and allow it to crystallize at 70°C for 10 hours. After filtration, wash with deionized water until neutral and then freeze-dry to obtain the Mg / Al-CO₃-LDH precursor.
[0052] Prepare a solution by dissolving 12 parts of HEDP in 100 mL of ethylene glycol. Then, add 1 part of Mg / Al-CO3-LDH precursor to the HEDP solution and stir continuously. During stirring, add an alkaline buffer solution to adjust the pH to 4.5. Pour the solution into a three-necked flask and crystallize at 150 °C for 5 hours. After cooling, filter the solution, wash with deionized water and alcohol until neutral, and then freeze-dry to obtain the HEDP intercalated hydrotalcite additive.
[0053] Example 5 First, weigh 2 parts NaOH and add them to deionized water to prepare solution A. Then, weigh 1 part anhydrous Na₂CO₃ and add it to deionized water to prepare solution B. Next, weigh 3 parts Mg(NO₃)₂·6H₂O and 1 part Al(NO₃)₃·9H₂O and add them to deionized water to prepare solution C. Slowly add solution C to solution B to prepare solution D. Then, slowly add solution D to solution A to prepare solution E, maintaining the pH of solution E at 9.5. Finally, add solution E to a three-necked flask and allow it to crystallize at 90°C for 6 hours. After filtration, wash with deionized water until neutral and then freeze-dry to obtain the Mg / Al-CO₃-LDH precursor.
[0054] Prepare a solution by dissolving 4 parts of HEDP in 100 mL of ethylene glycol. Then, add 1 part of Mg / Al-CO3-LDH precursor to the HEDP solution and stir continuously. During stirring, add an alkaline buffer solution to adjust the pH to 4.5. Pour the solution into a three-necked flask and crystallize at 140 °C for 6 hours. After cooling, filter the solution, wash with deionized water and alcohol until neutral, and then freeze-dry to obtain the HEDP intercalated hydrotalcite additive.
[0055] The intercalation admixture Mg / Al-HEDP-LDH synthesized in Example 5 was added to the cement slurry formulation. The cement slurry formulation and thickening time are shown in Table 1 below: Table 1 Cement slurry formulation and thickening time
[0056] In Table 1, the thickening experiment temperature was 90℃, the experiment pressure was 45MPa, and the heating time was 45min.
[0057] Figure 2 Table 1 shows the thickening curves of each cement at 90℃, where Figures (a) to (d) correspond to the thickening curves of cements with serial numbers C00, H03, H05, and H07 at 90℃, respectively.
[0058] From Table 1 and Figure 2 It can be seen that the intercalation admixture Mg / Al-HEDP-LDH prepared in this invention has a certain retarding effect at 90℃, indicating that it can effectively adjust the thickening time of cement paste under medium temperature conditions.
[0059] The intercalating admixture Mg / Al-HEDP-LDH synthesized in Example 5 was combined with the high-temperature retarder ZH-6 and applied to cement slurry. The cement slurry formulation and thickening time are shown in Table 2 below. Table 2 Thickening time of the compounded intercalation enhancer Mg / Al-HEDP-LDH and high-temperature retarder ZH-6
[0060] Figure 3 The thickening curves of the intercalation admixture and high-temperature retarder ZH-6 in Example 5, when applied to cement at different temperatures, are shown in Figures (a)-(h), which correspond to the thickening curves of cement with serial numbers G1, G2, G3, G4, G5, G6, G7, and G8 at different temperatures, respectively.
[0061] From Table 2 and Figure 3It can be seen that when the high-temperature cement slurry system prepared by compounding the intercalating admixture Mg / Al-HEDP-LDH with the high-temperature retarder ZH-6 is subjected to thickening experiments at 120~180℃, the thickening time is increased compared with the addition of ZH-6 alone. Moreover, the addition of the intercalating reinforcing admixture Mg / Al-HEDP-LDH to the cement slurry can improve the temperature fluctuation problem that occurred at the end of the heating stage of ZH-6, and the thickening curve is more stable compared with the addition of ZH-6 alone.
[0062] The intercalation admixture Mg / Al-HEDP-LDH synthesized in Example 5 and the high-temperature retarder ZH-6 were simultaneously added to the high-temperature cement slurry system, and their strength development under large temperature difference conditions was tested. The results are shown in Table 3 below.
[0063] Table 3. Effect of Mg / Al-HEDP-LDH on the strength of cement paste under different top and bottom temperature differences (MPa)
[0064] Table 3 shows that when the curing temperature is 40℃ and the precast temperature reaches 180℃, the 48-hour compressive strength of the cement stone gradually increases as the precast temperature decreases and the temperature difference gradually decreases. When the temperature difference is 140℃, the compressive strength of the cement stone can reach over 5MPa. When the curing temperature is 90℃ and the precast temperature reaches 180℃, the 48-hour compressive strength of the cement stone can reach over 9MPa. When the precast temperature is less than 160℃, the 48-hour compressive strength of the cement stone is always higher than 10MPa. Furthermore, the compressive strength increases with increasing curing time. Based on these results, it can be concluded that under large temperature difference conditions, the incorporation of the intercalation reinforcing agent Mg / Al-HEDP-LDH can effectively improve the problem of slow strength development of the high-temperature oil well cement retarder ZH-6 under large temperature difference conditions.
[0065] The embodiments described above are merely illustrative of implementation methods of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention.
Claims
1. A method for preparing a cementing intercalation admixture, characterized in that, Includes the following steps: Step S1: Prepare intercalated hydrotalcite precursor by coprecipitation method, wherein the anion of the intercalated hydrotalcite precursor is carbonate ion; Step S2: Dissolve hydroxyethylidene diphosphonic acid in a solvent to prepare a first solution, add the intercalated hydrotalcite precursor to the first solution, adjust the pH value to completely dissolve the intercalated hydrotalcite precursor, and obtain a second solution. Step S3: Perform ion exchange on the second solution at a set temperature, cool it, and then process it to obtain the intercalation additive.
2. The method for preparing the cementing intercalation admixture according to claim 1, characterized in that, The intercalated hydrotalcite precursor is a Mg / Al-CO3-LDH precursor.
3. The method for preparing the cementing intercalation admixture according to claim 2, characterized in that, When preparing the intercalation admixture, the weight ratio of the Mg / Al-CO3-LDH precursor to the hydroxyethylidene diphosphonic acid is 1:1~12.
4. The method for preparing the cementing intercalation admixture according to claim 2, characterized in that, The preparation process of the Mg / Al-CO3-LDH precursor includes the following steps: Step S1-1: Add NaOH to deionized water to prepare solution A, add Na2CO3 to deionized water to prepare solution B, and add Mg(NO3)2 and Al(NO3)3 to deionized water to prepare solution C; Step S1-2: Add solution C to solution B to obtain solution D; Step S1-3: Add solution A to solution D to prepare solution E, and adjust the pH value of solution E; Step S1-4: Perform a co-precipitation reaction on the E solution at a selected temperature; Steps S1-5: Filter, wash and dry the solution after the reaction to obtain the Mg / Al-CO3-LDH precursor.
5. The method for preparing the cementing intercalation admixture according to claim 4, characterized in that, The components used to prepare the Mg / Al-CO3-LDH precursor are in the following weight ratio: 2-6 parts NaOH, 1-3 parts Na2CO3, 3-9 parts Mg(NO3)2, and 1-3 parts Al(NO3)3.
6. The method for preparing the cementing intercalation admixture according to claim 4, characterized in that, In steps S1-3, the pH value of the E solution is adjusted to 9.5~10.
5.
7. The method for preparing the cementing intercalation admixture according to claim 4, characterized in that, In steps S1-4, the selected temperature is 70~90℃, and the co-precipitation reaction time is 6~10 hours.
8. The method for preparing the cementing intercalation admixture according to claim 2, characterized in that, In step S2, the solvent is ethylene glycol.
9. The method for preparing the cementing intercalation admixture according to claim 2, characterized in that, In step S2, the pH value is adjusted to 3.5~4.
5.
10. The method for preparing the cementing intercalation admixture according to claim 2, characterized in that, In step S3, the set temperature is 130~150℃, and the ion exchange time is 5~7 hours.
11. A cementing intercalation admixture, characterized in that, The intercalation admixture is prepared by the method described in any one of claims 1-10.
12. A cement slurry for cementing wells, characterized in that, It includes the following components: cementing intercalation admixture as described in claim 11, cement, water, fluid loss reducing agent, dispersant, and defoamer.
13. The application of the cement slurry in well cementing according to claim 12, characterized in that, The application temperature of the cement slurry is 70~110℃.
14. A cement slurry for cementing wells, characterized in that, It includes the following components: cementing intercalation admixture as described in claim 11, cement, quartz sand, water, fluid loss reducing agent, dispersant, and high-temperature retarder.
15. The application of the cement slurry in well cementing according to claim 14, characterized in that, The application temperature of the cement slurry is 70~180℃.