Galactomannan modified gel loaded inorganic salt type early strength agent and preparation method thereof

Abstract

The invention relates to the technical field of oil field chemicals and admixtures for oil well cement, in particular to a galactomannan modified gel loaded inorganic salt type early strength agent and a preparation method thereof, and aims to solve the problems that the addition amount of a current early strength agent is too large and is difficult to control, the slurry performance and the later strength of set cement are affected and the like. The invention provides a preparation method of a galactomannan modified gel loaded inorganic salt type early strength agent. The preparation method comprises the following steps: dissolving a modifier in deionized water; adding an inorganic salt solid into the modifier solution; adding an initiator into a beaker containing deionized water; respectively and sequentially adding a liquid monomer and a white powder solid cross-linking agent into the modifier-containing inorganic salt solution; dropwise adding an initiator solution into the beaker filled with the mixed solution, and reacting completely; and shearing and drying the obtained modified gel sample. The early strength agent is stable in structure, has slow release performance, is convenient to store, has a good effect of promoting cement hydration at low temperature, and can be used in deepwater and ultra-deepwater shallow stratum well cementation cement paste.

Description

Technical Field

[0001] The invention relates to the technical field of oilfield chemicals and additives for oil well cement, and in particular to a galactomannan modified gel loaded inorganic salt type early strength agent and a preparation method thereof. Background Art

[0002] Deepwater and ultra-deepwater areas are rich in oil and gas resources and have become the most valuable strategic successor energy. Due to the special development environment of oil and gas resources in deepwater and ultra-deepwater areas, the oil and gas development process becomes difficult and complicated, such as water-gas crossflow in shallow layers, loose formation collapse, low temperature, decomposition of hydrates and easy formation leakage, which affects the cost and quality of cementing and has a serious impact on the subsequent smooth production. However, among the various harsh environmental factors, the most severe challenge in the process of deepwater cementing is low temperature (-1.7-5.0℃). Because the hydration and hardening speed of G-grade oil well cement commonly used for cementing is greatly slowed down in low temperature environment, it is difficult to obtain early strength and the ability to prevent shallow water-gas flow in a short time, and it cannot meet the cementing requirements. Because the early strength does not meet the requirements, under the scouring of shallow water-gas flow, it will invade the cement slurry to produce crossflow, thereby causing micro-channeling grooves in the cement slurry. This leads to failure of cement ring isolation and reduced safety of oil and gas wells. For cementing in deepwater, ultra-deepwater and polar regions, cement slurry must meet the requirements of high early strength and short "transition time" for gel strength development. Currently, in oil and gas drilling and production projects, when the final strength of cement stone reaches 3.45-7.00MPa, it can fully meet most operational requirements. Therefore, developing a new low-temperature cementing material system, shortening the cement slurry waiting time, and improving the early strength are the unconventional low-temperature cementing problems that need to be solved urgently.

[0003] At present, the common method to improve the early mechanical properties of cement paste is to add admixtures such as early strength agent. Early strength agent can accelerate the hydration and hardening speed of cement. After addition, it can directly react with certain chemical components of oil well cement to promote the cement hydration process. However, the early strength agent in the traditional sense has the problem of excessive addition, which can easily cause problems such as reduced fluidity of cement slurry and poor grouting effect. In addition, there are also problems such as increased shrinkage of cement paste, resulting in cracking of cement paste, poor resistance, and later strength shrinkage. According to research, the existing early strength agents generally do not work well at low temperatures. Summary of the invention

[0004] The object of the present invention is to provide a galactomannan modified gel loaded inorganic salt type early strength agent and a preparation method thereof. The method has high operability, short preparation time and low cost. The early strength agent prepared by loading inorganic salt with galactomannan modified gel as a carrier has a stable structure, has a sustained release property, is easy to store, has a good effect on promoting cement hydration at low temperature, has little effect on the engineering performance of cement slurry, can be used in cement slurry for cementing in deep water and ultra-deep water shallow formations, solves the current problem that the early strength agent is added too much and is difficult to control, affects the slurry performance and the later strength of cement stone, and has broad market application prospects.

[0005] In order to solve the above technical problems, the technical solution provided by the present invention is:

[0006] In a first aspect, the present invention provides a method for preparing a galactomannan modified gel-loaded inorganic salt-type early strength agent, comprising the following steps:

[0007] Step (1): dissolving the modifier in deionized water;

[0008] Step (2): adding the inorganic salt solid to the modifier solution and stirring it magnetically to completely dissolve it to form a uniform and stable solution;

[0009] Step (3): Add the initiator into a beaker containing deionized water and stir to dissolve;

[0010] Step (4): liquid monomer and white powder solid cross-linking agent are added to the inorganic salt solution containing the modifier in sequence and stirred until completely dissolved and uniform;

[0011] Step (5): transfer the beaker containing the mixed solution to a water bath, and use a rubber-tipped dropper to uniformly add the initiator solution to the beaker containing the mixed solution while stirring. After the mixing is completed, seal the beaker with plastic wrap and remove it after the reaction is complete;

[0012] Step (6): Cut the obtained modified gel sample into pieces, put it into a freeze dryer for drying, take it out and grind it to obtain a modified gel early strength agent sample loaded with inorganic salt.

[0013] Furthermore, the modifier used in step (1) is galactomannan.

[0014] Furthermore, the inorganic salt used in step (2) is one or more of calcium chloride, calcium nitrate, calcium nitrite, calcium formate, potassium chloride, potassium nitrate, potassium nitrite, potassium sulfate, potassium sulfite, sodium chloride, sodium nitrate, sodium nitrite, sodium sulfate, sodium silicate, sodium carbonate, lithium chloride, lithium sulfate, lithium nitrate, and lithium nitrite.

[0015] Furthermore, the initiator used in step (3) is ammonium persulfate.

[0016] Furthermore, in step (4), the liquid monomer is acrylic acid.

[0017] Furthermore, in step (4), the white powder solid cross-linking agent is N,N-methylenebisacrylamide.

[0018] Furthermore, the mixed solution in step (5) comprises 2.0-5.0 parts by weight of galactomannan, 50-100 parts by weight of deionized water, 20-30 parts by weight of inorganic salt solids, 10-30 parts by weight of liquid monomers and 0.02-0.3 parts by weight of white powder solid crosslinking agent.

[0019] Furthermore, in step (5), the reaction temperature is 60-70° C. and the reaction time is 4-6 h.

[0020] Furthermore, the drying method used in step (6) is low-temperature freeze drying, and the drying time is 5-8 days.

[0021] In a second aspect, the present invention provides a galactomannan modified gel loaded with inorganic salt type early strength agent prepared by the preparation method of the galactomannan modified gel loaded with inorganic salt type early strength agent.

[0022] The reaction process of the above-mentioned galactomannan modified gel loaded with inorganic salt type early strength agent is as follows:

[0023] Acrylic acid is a hydrophilic monomer that is miscible with water and has a simple structure. It is one of the simplest unsaturated acids and consists of a vinyl group and a carboxyl group. Under certain conditions, it can self-polymerize when it encounters peroxide, and the polymerization speed is very fast. Ammonium persulfate is an inorganic peroxide initiator that can dissolve in water to undergo self-polymerization reaction. It is non-toxic and harmless, and has simple and stable storage. N,N-methylenebisacrylamide (BIS) has two identical and highly reactive functional group structures. As a cross-linking agent, it can quickly and efficiently transform the self-polymerized linear structure of acrylic acid carbon-carbon double bonds into a three-dimensional network structure. The addition of galactomannan can enhance the hydrogen bond cross-linking effect of the hydrogel system. The four act simultaneously and promote each other's reaction, which is conducive to the formation of a more uniform and dense airborne network structure of the hydrogel. In the synthesis process of galactomannan modified gel, the selected inorganic salt ions can enter the network structure of the hydrogel, and under a certain osmotic pressure difference between the inside and the outside, the galactomannan modified gel can release the inorganic salt ions.

[0024] The galactomannan modified gel loaded with inorganic salt type early strength agent prepared by the present invention uses gel as a carrier and inorganic salt as a loaded coagulant, and can achieve the slow release of early strength coagulant ions. In addition, the galactomannan modified gel has good compatibility with cement paste and will not have a significant impact on the engineering properties of the paste. At the same time, the synthesis method of the above medicines is simple, the reaction time is short, it is easy to store, there are many sources, and the cost is low.

[0025] Based on the above technical solutions, the technical effects that can be achieved by the present invention are:

[0026] (1) The early strength agent has a slow-release accelerating effect and has little effect on the later strength;

[0027] (2) The early strength agent has good stability and is easy to store and transport;

[0028] (3) The raw materials of the early strength agent are widely available and low in cost, which has the advantages of reducing costs and increasing efficiency;

[0029] (4) The preparation method of the early strength agent is simple, the reaction time is short, and large-scale production can be achieved.

[0030] In summary, the present invention uses acrylic acid as a monomer, N,N-methylenebisacrylamide as a cross-linking agent, and ammonium persulfate as an initiator to synthesize a hydrogel. By adding galactomannan, the hydrogen bond cross-linking of the hydrogel system is increased, and a more uniform spatial network structure can be formed. Inorganic salt early strength agents are selected for incorporation to prepare galactomannan modified gel-loaded inorganic salt early strength agent. The early strength agent has good compatibility with cement paste, can achieve a slow-release accelerating coagulation effect, and has little effect on the later strength, and the accelerating coagulation process is controllable. It overcomes the problems that the current early strength agent has a great influence on the engineering performance of the paste, the amount of early strength agent is large, the accelerating coagulation process is uncontrollable, and it is easy to cause shrinkage cracking of cement stone and poor later strength. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0032] Figure 1 This is the Fourier infrared spectrum of the galactomannan modified gel loaded with inorganic salt type early strength agent prepared in Example 1;

[0033] Figure 2 This is a scanning electron microscope image of the galactomannan modified gel loaded with an inorganic salt-type early strength agent prepared in Example 1;

[0034] Figure 3 The conductivity of the galactomannan modified gel loaded with inorganic salt type early strength agent prepared in Example 1 added to water;

[0035] Figure 4 The conductivity of the galactomannan modified gel loaded with inorganic salt type early strength agent prepared in Example 1 added to the cement paste;

[0036] Figure 5 This is the effect of the galactomannan modified gel loaded with inorganic salt type early strength agent prepared in Example 1 on the compressive strength of cement paste. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical scheme and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention, that is, the embodiments described are only part of the embodiments of the present invention, rather than all of the embodiments.

[0038] Therefore, the following detailed description of the embodiments of the present invention is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative work are within the scope of protection of the present invention.

[0039] Unless otherwise specified, the experimental methods used in the following examples are all conventional methods; the reagents, materials, etc. used in the following examples, unless otherwise specified, can be obtained from commercial channels.

[0040] The present invention provides a galactomannan modified gel loaded with inorganic salt early strength agent and a preparation method thereof, which comprises the following steps:

[0041] (1) dissolving 2.0-5.0 parts by weight of galactomannan in 50-100 parts by weight of deionized water;

[0042] (2) Weigh 20-30 parts by weight of inorganic salt solid, add it to the solution of step (1), and stir it magnetically to completely dissolve it to form a uniform and stable solution;

[0043] (3) Weigh 0.02-0.3 parts by weight of an initiator and add it to a beaker containing 10-40 parts by weight of deionized water and stir to dissolve;

[0044] (4) Weigh 10-3 parts by weight of liquid monomer and 0.02-0.3 parts by weight of white powder solid crosslinking agent, add them to the inorganic salt solution of step (2) and stir until they are completely dissolved;

[0045] (5) Transfer the beaker containing the mixed solution in step (4) above to a water bath at 60-70°C, and use a rubber-tipped dropper to slowly and uniformly add the initiator solution obtained in step (3) above to the beaker containing the mixed solution, stirring while adding. After the mixing is completed, seal the beaker with plastic wrap and allow it to react for 4-6 hours before taking it out;

[0046] (6) Cut the galactomannan modified gel sample obtained in the above step (5) into pieces, put it into a freeze dryer and dry it for 5-8 days, take it out and grind it to obtain the galactomannan modified gel early strength agent sample loaded with inorganic salt.

[0047] In step (2), the inorganic salt is one or more of calcium chloride, calcium nitrate, calcium nitrite, calcium formate, potassium chloride, potassium nitrate, potassium nitrite, potassium sulfate, potassium sulfite, sodium chloride, sodium nitrate, sodium nitrite, sodium sulfate, sodium silicate, sodium carbonate, lithium chloride, lithium sulfate, lithium nitrate, and lithium nitrite.

[0048] In step (3), the initiator is ammonium persulfate.

[0049] In step (4), the liquid monomer is acrylic acid, and the white powder solid cross-linking agent is N,N-methylenebisacrylamide.

[0050] The galactomannan modified gel loaded inorganic salt early strength agent provided by the invention is a slow-release early strength agent for cementing cement in deep water and ultra-deep water shallow formations, and is particularly suitable for cementing cement slurry systems in deep water, ultra-deep water shallow formations and polar regions.

[0051] Galactomannan is a water-soluble heteropolysaccharide extracted from the endosperm of leguminous plant seeds. It is a neutral semi-fibrous polymer with a wide range of sources and low preparation costs. Galactomannan has high-concentration gel properties and excellent thickening and stabilizing abilities. Its application in cement slurry can increase the suspension stability of cement slurry. At the same time, it is applied to hydrogel materials to increase the hydrogen bond cross-linking effect in the hydrogel system, forming a more uniform spatial network structure to load inorganic salts, which can achieve the slow release of early strength accelerating ions, thereby achieving the dual purpose of improving slurry performance and improving the low-temperature strength of cement paste.

[0052] 1. Preparation of galactomannan modified gel loaded with inorganic salt type early strength agent

[0053] Embodiment 1

[0054] A galactomannan modified gel loaded with inorganic salt type early strength agent and a preparation method thereof, specifically comprising the following steps:

[0055] Weigh 2 parts by mass of galactomannan and fully dissolve it in a beaker containing 90 parts by mass of deionized water. Weigh 24 parts by mass of calcium chloride and add it to the above solution. Stir it magnetically to completely dissolve it to form a uniform and stable solution. Weigh 0.25 parts by mass of ammonium persulfate and add it to a beaker containing 10 parts by mass of deionized water and stir it thoroughly to dissolve. Weigh 25 parts by mass of acrylic acid and 0.13 parts by mass of N,N-methylenebisacrylamide and add them to the calcium chloride solution in turn and stir thoroughly until completely dissolved. Subsequently, transfer the beaker containing the mixed solution to a 65°C water bath, and use a rubber-tipped dropper to slowly and uniformly add the ammonium persulfate solution to the beaker containing the mixed solution, stirring while adding. After mixing is completed, seal the beaker with plastic wrap and allow it to react for 4 hours before taking it out. The obtained galactomannan modified gel sample was cut into pieces, placed in a freeze dryer and dried for 5 days, taken out and ground to obtain the galactomannan modified gel loaded with inorganic salt type early strength agent sample.

[0056] Embodiment 2

[0057] A galactomannan modified gel loaded with inorganic salt type early strength agent and a preparation method thereof, specifically comprising the following steps:

[0058] Weigh 3 parts by mass of galactomannan and fully dissolve it in a beaker containing 80 parts by mass of deionized water. Weigh 24 parts by mass of sodium chloride and add it to the above solution. Stir it magnetically to completely dissolve it to form a uniform and stable solution. Weigh 0.13 parts by mass of ammonium persulfate and add it to a beaker containing 20 parts by mass of deionized water and stir it thoroughly to dissolve. Weigh 17.65 parts by mass of acrylic acid and 0.11 parts by mass of N,N-methylenebisacrylamide and add them to the sodium chloride solution in sequence and stir thoroughly until they are completely dissolved. Subsequently, the beaker containing the mixed solution is transferred to a 60°C water bath, and the ammonium persulfate solution is slowly and uniformly added to the beaker containing the mixed solution with a rubber dropper, stirring while adding. After the mixing is completed, seal the beaker with plastic wrap and allow it to react for 5 hours before taking it out. The obtained galactomannan modified gel sample was cut into pieces, placed in a freeze dryer and dried for 6 days, taken out and ground to obtain the galactomannan modified gel loaded with inorganic salt type early strength agent sample.

[0059] Embodiment 3

[0060] A galactomannan modified gel loaded with inorganic salt type early strength agent and a preparation method thereof, specifically comprising the following steps:

[0061] Weigh 2.5 parts by mass of galactomannan and fully dissolve it in a beaker containing 70 parts by mass of deionized water. Weigh 26 parts by mass of lithium sulfate and sodium nitrite in a mass ratio of 1:1 and add them to the above solution. Stir magnetically to completely dissolve it to form a uniform and stable solution. Weigh 0.11 parts by mass of ammonium persulfate and add it to a beaker containing 30 parts by mass of deionized water and stir it thoroughly to dissolve. Weigh 11.11 parts by mass of acrylic acid and 0.11 parts by mass of N,N-methylenebisacrylamide and add them to the mixed solution of lithium sulfate and sodium nitrite in turn and stir thoroughly until completely dissolved. Subsequently, the beaker containing the mixed solution is transferred to a 70°C water bath, and the ammonium persulfate solution is slowly and uniformly added to the beaker containing the mixed solution with a rubber dropper, stirring while adding. After the mixing is completed, seal the beaker with plastic wrap and allow it to react for 6 hours before taking it out. The obtained galactomannan modified gel sample was cut into pieces, placed in a freeze dryer and dried for 8 days, taken out and ground to obtain the galactomannan modified gel loaded with inorganic salt type early strength agent sample.

[0062] Embodiment 4

[0063] A galactomannan modified gel loaded with inorganic salt type early strength agent and a preparation method thereof, specifically comprising the following steps:

[0064] Weigh 2 parts by mass of galactomannan and fully dissolve it in a beaker containing 60 parts by mass of deionized water. Weigh 28 parts by mass of lithium chloride and add it to the above solution. Stir it magnetically to completely dissolve it to form a uniform and stable solution. Weigh 0.177 parts by mass of ammonium persulfate and add it to a beaker containing 40 parts by mass of deionized water and stir it thoroughly to dissolve. Weigh 25 parts by mass of acrylic acid and 0.177 parts by mass of N,N-methylenebisacrylamide and add them to the lithium chloride solution in turn and stir thoroughly until completely dissolved. Subsequently, the beaker containing the mixed solution is transferred to a 60°C water bath, and the ammonium persulfate solution is slowly and uniformly added to the beaker containing the mixed solution with a rubber dropper, stirring while adding. After the mixing is completed, seal the beaker with plastic wrap and allow it to react for 4 hours before taking it out. The obtained galactomannan modified gel sample was cut into pieces, placed in a freeze dryer and dried for 5 days, taken out and ground to obtain the galactomannan modified gel loaded with inorganic salt type early strength agent sample.

[0065] Embodiment 5

[0066] A galactomannan modified gel loaded with inorganic salt type early strength agent and a preparation method thereof, specifically comprising the following steps:

[0067] Weigh 2 parts by mass of galactomannan and fully dissolve it in a beaker containing 50 parts by mass of deionized water. Weigh 30 parts by mass of calcium chloride and add it to the above solution. Stir it magnetically to completely dissolve it to form a uniform and stable solution. Weigh 0.05 parts by mass of ammonium persulfate and add it to a beaker containing 40 parts by mass of deionized water and stir it thoroughly to dissolve. Weigh 17.65 parts by mass of acrylic acid and 0.088 parts by mass of N,N-methylenebisacrylamide and add them to the calcium chloride solution in turn and stir thoroughly until completely dissolved. Subsequently, transfer the beaker containing the mixed solution to a 70°C water bath, and use a rubber-tipped dropper to slowly and uniformly add the ammonium persulfate solution to the beaker containing the mixed solution, stirring while adding. After mixing is completed, seal the beaker with plastic wrap and allow it to react for 5 hours before taking it out. The obtained galactomannan modified gel sample was cut into pieces, placed in a freeze dryer and dried for 7 days, taken out and ground to obtain the galactomannan modified gel loaded with inorganic salt type early strength agent sample.

[0068] Comparative examples and their evaluation data:

[0069] In order to illustrate the effect of the present invention, from the perspective of cement slurry conductivity and early compressive strength, a blank cement slurry and a cement slurry mixed with calcium chloride were used as comparative examples for further analysis. Figure 4 and Figure 5 As shown. The conductivity of the cement paste with calcium chloride remained basically unchanged at first, and then dropped rapidly after about 6 hours. This is because the cement hydration reaction began, the cement paste began to harden, and the ions in the cement paste participated in the hydration reaction, resulting in a decrease in ion concentration, which led to a decrease in the conductivity of the cement paste; while the conductivity of the pure cement paste remained basically unchanged, indicating that the addition of calcium chloride can promote the hydration reaction of the cement paste in advance and has a coagulation-promoting effect on the cement paste. As for the compressive strength of cement paste, pure cement still had no strength after curing for 2 days, and the compressive strength of pure cement paste was 4.60MPa after curing for 3 days; the compressive strength of cement paste after curing for 1 day after adding calcium chloride was 1.70MPa, the compressive strength of cement paste after curing for 2 days was 4.56MPa, and the compressive strength of cement paste after curing for 3 days reached 7.00MPa or above, which was 7.40MPa.

[0070] 2. Characteristic Analysis of Galactomannan Modified Gel Loaded Inorganic Salt Type Early Strength Agent

[0071] Depend on Figure 1 It can be seen that 3413cm -1 The wide peak is the stretching vibration absorption peak of -OH, at 2918cm -1 A saturated -CH stretching vibration absorption peak appears at 3350cm -1The NH stretching vibration absorption peak at 1637cm is the amide group, indicating that N,N-methylenebisacrylamide participates in the polymerization reaction. -1 The stretching vibration absorption peak of carboxylic acid C=O is at 1455cm -1 The peak at the center is the stretching vibration absorption peak of carboxyl CO, indicating that acrylic acid participates in the polymerization reaction of galactomannan modified gel. It proves that galactomannan modified chemical cross-linked gel with acrylic acid as monomer and N,N-methylenebisacrylamide as cross-linking agent has been successfully synthesized.

[0072] Depend on Figure 2 It can be seen that the galactomannan modified gel has a significant network structure, with more micropores and a dense structure. At this time, the porous galactomannan modified gel can absorb more inorganic salt ions. After adding the galactomannan modified gel to the cement slurry, it can release more inorganic salt ions under the osmotic pressure of the cement slurry, and its slow-release accelerating coagulation effect is better and the performance is more stable.

[0073] Depend on Figure 3 It can be seen that the conductivity of galactomannan modified gel in water showed a slow upward trend and then remained stable, indicating that galactomannan modified gel can slowly release Ca during the swelling process. 2+ , to achieve the purpose of sustained release.

[0074] Depend on Figure 4 It can be seen that the conductivity of the cement paste system with galactomannan modified gel loaded with inorganic salt early strength agent is generally divided into three stages. The conductivity of the cement paste increases slowly in the early stage. This is due to the Ca 2+ The ions in the cement slurry are released, which increases the ion concentration in the cement slurry and thus increases its conductivity. The conductivity of the cement slurry remains basically unchanged in the middle stage, because the hydration reaction of the cement slurry has not yet started. At this time, the ion concentration in the cement slurry remains unchanged, and its conductivity remains stable. The conductivity of the cement slurry begins to decline in the late stage, because the cement slurry begins to hydrate and the Ca in the cement slurry 2+ The ion concentration is consumed, and the conductivity of the cement slurry decreases. This shows that the addition of galactomannan modified gel can promote the hydration reaction of the cement slurry, indicating that galactomannan modified gel has a coagulation-promoting effect on the cement slurry.

[0075] Depend on Figure 5 It can be seen that the compressive strength of cement paste samples with galactomannan modified gel loaded with inorganic salt early strength agent is higher than that of pure cement paste at all curing ages. In addition, it can be observed that the strength at 1 day and 2 days is lower than that of cement paste with calcium chloride, which is a manifestation of the slow-release accelerating effect of galactomannan modified gel loaded with inorganic salt early strength agent in the early stage.

[0076] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a galactomannan modified gel-loaded inorganic salt-type early strength agent, It is characterized in that The following steps are involved: Step (1): dissolving the modifier in deionized water; Step (2): adding the inorganic salt solid to the modifier solution and stirring it magnetically to completely dissolve it to form a uniform and stable solution; Step (3): Add the initiator into a beaker containing deionized water and stir to dissolve; Step (4): liquid monomer and white powder solid cross-linking agent are added to the inorganic salt solution containing the modifier in sequence and stirred until completely dissolved and uniform; Step (5): transfer the beaker containing the mixed solution to a water bath, and use a rubber-tipped dropper to uniformly add the initiator solution to the beaker containing the mixed solution while stirring. After the mixing is completed, seal the beaker with plastic wrap and remove it after the reaction is complete; Step (6): Cut the obtained modified gel sample into pieces, put it into a freeze dryer for drying, take it out and grind it to obtain a modified gel early strength agent sample loaded with inorganic salt.

2. The method for preparing the galactomannan modified gel loaded with inorganic salt type early strength agent according to claim 1, It is characterized in that The modifying agent used in the step (1) is galactomannan.

3. The method for preparing the galactomannan modified gel loaded with inorganic salt type early strength agent according to claim 1, It is characterized in that The inorganic salt used in the step (2) is one or more of calcium chloride, calcium nitrate, calcium nitrite, calcium formate, potassium chloride, potassium nitrate, potassium nitrite, potassium sulfate, potassium sulfite, sodium chloride, sodium nitrate, sodium nitrite, sodium sulfate, sodium silicate, sodium carbonate, lithium chloride, lithium sulfate, lithium nitrate, and lithium nitrite.

4. The method for preparing the galactomannan modified gel loaded with inorganic salt type early strength agent according to claim 1, It is characterized in that The initiator used in step (3) is ammonium persulfate.

5. The method for preparing the galactomannan modified gel loaded with inorganic salt type early strength agent according to claim 1, It is characterized in that The liquid monomer in step (4) is acrylic acid.

6. The method for preparing the galactomannan modified gel loaded with inorganic salt type early strength agent according to claim 1, It is characterized in that The white powder solid cross-linking agent in step (4) is N,N-methylenebisacrylamide.

7. The method for preparing the galactomannan modified gel loaded with inorganic salt type early strength agent according to claim 1, It is characterized in that The mixed solution in step (5) comprises 2.0-5.0 parts by weight of galactomannan, 50-100 parts by weight of deionized water, 20-30 parts by weight of inorganic salt solid, 10-30 parts by weight of liquid monomer and 0.02-0.3 parts by weight of white powder solid crosslinking agent.

8. The method for preparing the galactomannan modified gel loaded with inorganic salt type early strength agent according to claim 1, It is characterized in that In the step (5), the reaction temperature is 60-70° C. and the reaction time is 4-6 h.

9. The method for preparing the galactomannan modified gel loaded with inorganic salt type early strength agent according to claim 1, It is characterized in that The drying method used in step (6) is low-temperature freeze drying, and the drying time is 5-8 days.

10. A galactomannan modified gel loaded with inorganic salt type early strength agent prepared by the preparation method of the galactomannan modified gel loaded with inorganic salt type early strength agent as claimed in any one of claims 1 to 9.

Images