Pre-gelatinized starch-based gel plugging agent and preparation method thereof

Abstract

The invention provides a pregelatinized starch-based gel plugging agent and a preparation method thereof, and belongs to the technical field of petrochemical industry. The adhesive comprises the following components in percentage by weight: 3-4 wt% of modified starch; 3 to 4 wt% of an amide compound; 0.1 to 0.2 wt% of a cross-linking agent; 0.05 to 0.1 wt% of an initiator; 0.1 to 0.2 wt% of a high temperature stabilizer; 0.1 to 0.2 wt% of a deoxidant; and the balance of clear water. According to the pregelatinized starch-based gel plugging agent, modified starch is used as a rigid framework, acrylamide is used as a net-shaped multi-chain macromolecular copolymer of a flexible branch chain, a plurality of macromolecular copolymer long chains are intertwined and associated through a cross-linking agent, and as the standing time goes by, three stages of induction, gelling and stabilization are sequentially carried out, so that the pregelatinized starch-based gel plugging agent is obtained. A gelling stable structure with relatively high material strength is generated, and the material use efficiency of a fracture-vug type oil reservoir gel water plugging technology can be improved.

Description

Technical Field

[0001] This invention belongs to the field of petrochemical technology, specifically relating to a pregelatinized starch-based gel plugging agent and its preparation method. Background Technology

[0002] Edge water, bottom water, and injected water are the energy sources for oilfield development. Due to the heterogeneity of formation permeability, these waters often prematurely intrude into oil wells along high-permeability layers, increasing the water cut in the well's produced fluid and decreasing oil production. Oil well water shut-off refers to controlling water production from the oil well. The principle of chemical water shut-off is to inject chemical agents (plugging agents) from the oil well into high-permeability water-producing zones to reduce the permeability of the near-wellbore zone, control the production of injected water, bottom water, and edge water, and increase crude oil production. Currently used plugging agents are divided into two main categories: organic plugging agents and inorganic plugging agents, such as cement-based inorganic particle plugging agents, reactive precipitation plugging agents, polymer gel plugging agents, and composite plugging agents of organic resins and inorganic fillers.

[0003] For example, Chinese patent CN112143470A discloses a plugging material and its preparation method, as well as a plugging agent. The siloxane structure contained in this plugging material can be connected to the inorganic surface of cement through hydrogen bonds or chemical bonds (such as Si-O-Ca), realizing the integration of cement and plugging material, improving the density of the interface between cement and plugging material, strengthening the interfacial bonding strength, and giving the cement stone formed after the cement slurry hardens better compressive strength. In addition, a large number of carboxyl groups are introduced into the plugging material. After the cement and plugging material are integrated, the negative charge of the carboxyl groups is adsorbed on the surface of cement particles, making the surface of cement particles negatively charged, generating electrostatic repulsion, promoting the mutual dispersion of cement particles, destroying the flocculation structure, and releasing the water molecules that were trapped by flocculation, allowing them to participate in the flow, thereby improving the rheological properties of cement slurry and meeting the requirements of coiled tubing construction in high sulfur gas wells.

[0004] For example, Chinese patent CN105219365A discloses a cross-linked polymer gel plugging agent for medium and deep wells and its preparation method. The raw material components and weight contents are as follows: refined cotton sodium salt solution: 120 parts, acrylamide: (75-85) parts, ammonium persulfate: (13-17) parts, cerium sulfate: (2-5) parts, β-D-mannuronic acid (M): 4 parts, ammonium dihydrogen phosphate: (1-1.5) parts, composite silicate cement slurry: 100 parts, and hybrid microfiber: (150-200) parts; the water-cement ratio of the composite silicate cement slurry is 0.44; acrylamide, ammonium persulfate particles, and cerium sulfate particles are added to the refined cotton sodium salt solution in sequence to obtain cross-linked polymer gel, then β-D-mannuronic acid (M) is added, followed by composite silicate cement slurry and hybrid microfiber, and finally ammonium dihydrogen phosphate is added and stirred evenly to obtain the cross-linked polymer gel plugging agent for medium and deep wells. This cross-linked polymer gel plugging agent for medium and deep wells has strong resistance to high temperatures and pressures, and provides reliable plugging.

[0005] However, existing plugging agents have poor self-healing properties, toughness, and dilution resistance, and are insufficient in their ability to withstand continuous erosion from highly salinized bottom water. Therefore, it is necessary to develop a plugging agent with excellent self-healing properties, toughness, and dilution resistance, capable of withstanding continuous erosion from highly salinized bottom water, and possessing high strength, as well as its preparation method. Summary of the Invention

[0006] Based on the shortcomings of existing technologies, this invention aims to provide a pregelatinized starch-based gel plugging agent with excellent self-healing properties, toughness, and dilution resistance, capable of withstanding continuous erosion by highly mineralized bottom water and possessing high strength, as well as its preparation method.

[0007] The pregelatinized starch-based gel plugging agent of this invention uses modified starch as a rigid skeleton and acrylamide as a flexible branched network of multi-chain macromolecular copolymers. Multiple macromolecular copolymer long chains are intertwined and associated with each other by a crosslinking agent. As the standing time increases, it goes through three stages: induction, gelation, and stabilization, generating a gelled and stable structure with high material strength. This can improve the material utilization efficiency of gel plugging technology for fractured reservoirs.

[0008] To achieve the above objectives, the present invention employs the following technical solution:

[0009] A pregelatinized starch-based gel blocking agent, comprising the following components by weight percentage:

[0010] Modified starch: 3-4 wt%;

[0011] Amide compounds: 3-4 wt%;

[0012] Crosslinking agent: 0.1-0.2 wt%;

[0013] Initiator: 0.05-0.1 wt%;

[0014] High-temperature stabilizer: 0.1-0.2 wt%;

[0015] Oxygen scavenger: 0.1-0.2 wt%;

[0016] Clear water: remaining amount.

[0017] Preferably, the pregelatinized starch-based gelling agent comprises the following components by weight percentage:

[0018] Modified starch: 4 wt%;

[0019] Amide compounds: 4 wt%;

[0020] Crosslinking agent: 0.1 wt%;

[0021] Initiator: 0.05 wt%;

[0022] High temperature stabilizer: 0.1 wt%;

[0023] Oxygen scavenger: 0.1 wt%;

[0024] Clear water: remaining amount.

[0025] in,

[0026] The modified starch is selected from one or more of carboxymethyl wheat starch, carboxymethyl cassava starch, and carboxymethyl potato starch;

[0027] The preferred ingredient is carboxymethyl cassava starch.

[0028] The amide compound is an acrylamide monomer.

[0029] The crosslinking agent is selected from one or more of N,N-dimethylacrylamide, N,N-dimethylacetamide, methylenebisacrylamide and N,N-methylenebisacrylamide;

[0030] Preferably, the crosslinking agent is N,N-dimethylacrylamide.

[0031] The initiator is selected from one or more of sodium persulfate, potassium persulfate, and ammonium persulfate;

[0032] Preferably, the initiator is potassium persulfate.

[0033] The high-temperature stabilizer is selected from one or more of benzoyl peroxide, dibenzoyl peroxide, and cumene hydroperoxide.

[0034] Preferably, the high-temperature stabilizer is benzoyl peroxide.

[0035] The oxygen scavenger is selected from one or more of sodium sulfite, ammonium sulfite, and ammonium bisulfite;

[0036] Preferably, the oxygen scavenger is sodium sulfite.

[0037] The preparation method of the pregelatinized starch-based gel plugging agent includes the following steps: pre-stirring water in a device equipped with a stirrer; then adding modified starch to the water until the modified starch is completely gelatinized and thickened in the water, adding an amide compound and continuing to stir, then adding a crosslinking agent and stirring until completely dissolved; finally adding a high-temperature stabilizer, an initiator, and an oxygen scavenger, stirring until completely dissolved, and placing it in a constant temperature oven for aging until completely gelled to obtain the pregelatinized starch-based gel plugging agent.

[0038] The stirring speed during the above preparation process is always 300-400 rpm;

[0039] in,

[0040] The stirring time after adding the modified starch is 30-45 minutes.

[0041] The stirring time after adding the amide compound is 5-10 minutes.

[0042] The stirring time after adding the crosslinking agent is 5-10 minutes.

[0043] The stirring time after adding the high-temperature stabilizer, initiator and oxygen scavenger is 15-20 minutes.

[0044] The temperature of the constant temperature chamber is 130℃.

[0045] During the preparation process, the modified starch dissolves in water, and a small amount of water enters the amorphous region of the starch, while the starch granules retain their original crystalline state; this stage is the reversible water absorption stage. Subsequently, with continued heating and gelatinization, a large amount of water enters the starch interior, causing intermolecular association. Hydration occurs in the crystalline region of the starch, amylopectin depolymerizes, and amylose dissolves in water, significantly increasing viscosity and forming a viscous paste-like liquid; this stage is the irreversible water absorption stage. Finally, the hydrogen bonds within the starch continue to be broken, resulting in a greater degree of swelling. At this point, the double helix structure of amylopectin is destroyed, crystallization disappears, and amylose is fully dissolved in water, forming a starch-based aqueous solution. After hydrolysis, the modified starch produces… Hydroxyl groups are formed, and graft polymerization with amide compounds is carried out under the guidance of a crosslinking agent to form a polymeric product with restructured hydrogen bonds. After the modified starch is polymerized with amide compounds to form a polymer, a crosslinking agent containing hydroxyl functional groups is used to hydrolyze the polymer to form carboxyl groups, which then undergo dehydration condensation with polymer monomers to form new crosslinking functional groups. The long chains of the polymer are interconnected by the crosslinking agent, forming polymeric aggregates through intermolecular crosslinking. Subsequently, an initiator, stabilizer, and oxygen scavenger are added to the pre-prepared solution to delay the relaxation of the three-dimensional network structure of the gel system and even prevent premature bond breakage, thereby stabilizing the strength of the gel structure and finally obtaining the gel system.

[0046] The pregelatinized starch-based gel described in this invention is mainly based on physical, chemical, or biological enzymatic treatment (modified starch contains amylase). By altering the molecular structure, size, or aggregation state, or by grafting new functional groups, the properties of starch are changed, increasing the viscosity of the water-based starch solution and enhancing its physical stability and resistance to retrogradation. During gelatinization, branched molecules act as a backbone. Under the combined action of heat and water molecules, the association between starch granule molecules is disrupted, forming a relatively viscous water-based starch solution. Subsequently, a high-strength gel is formed through free radical graft copolymerization with acrylamide monomers and an initiator, exhibiting good swelling, elasticity, hydrophilicity, and biodegradability. Simultaneously, the appropriate addition of AM monomers can increase the brine absorption capacity of the starch-based hydrogel; a suitable amount of crosslinking agent can form a moderately crosslinked continuous network distribution, enhancing the water-locking capacity of the starch-based hydrogel and forming a continuous and robust spatial network macromolecular structure hydrogel. In the application of enhanced oil recovery in the petroleum industry, it exhibits good deep-penetration ability, strong shear resistance, good selective plugging, and extremely strong plugging ability.

[0047] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0048] 1. After pregelatinized starch-based gels are fully grafted and polymerized in water according to various reagents in proportion, the gel structure often encapsulates free and bound water molecules and sublimates into a gaseous state during vacuum drying. The three-dimensional network structure of the gel system is filled with densely adjacent pores. The grafting polymerization of pregelatinized starch and monomers can improve the stability of branched molecules as the main skeleton, improve the solution viscosity, and strengthen the inter-molecular entanglement, generating copolymers with higher molecular weight. Subsequently, using a cross-linking agent as the medium for connecting the molecular chains, and with the support of initiators and high-temperature stabilizers, the complete gelation stage can bear the diffusion and migration of water molecules and lock in a certain amount of water to prevent leakage. After absorbing water and swelling in the ionic valence state, the molecular chains fully extend and connect with each other, making the network structure larger and improving the efficiency of water molecule fixation, thus exhibiting good water retention performance.

[0049] 2. The main functional group of pregelatinized starch-based gel is a hydrophilic carboxyl group, which contains a large number of hydrogen bonds. The fracture surface cracks after damage are due to hydrogen bonding, which makes the three-dimensional network space of the gel system have strong reversible interlocking properties and recombine under dynamic cross-linking. New hydrophilic carboxyl groups will form on the damaged and exposed surface, and new hydrogen bonds will diffuse out, causing the macromolecular chains in the gel structure to entangle and associate again. The charged groups in the molecular chains will combine with polar groups through electrostatic bonding to form fan-shaped or columnar micelles, which support the self-healing ability of the network structure, repair the damaged fracture surface, and maintain the viscoelasticity and adhesion of the gel system.

[0050] 3. This invention uses a pregelatinized starch-based gel with a resin that has high water absorption capacity and is dominated by viscous forces. It has strong water absorption capacity, better balance between water absorption and network elasticity, and better compressive strength.

[0051] Figure and Table Description

[0052] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0053] Figure 1 These are starch gels from Example 1 and Comparative Example 1, along with their SEM microstructure characterization images.

[0054] Figures ab and b show the starch gel of Example 1 and its SEM microstructure characterization; Figures cd and d show the starch gel of Comparative Example 1 and its SEM microstructure characterization.

[0055] Figure 2 The image shows the polarized light microscopy characterization of the self-healing cross-section of starch gel.

[0056] Figure 3 The graph shows the change in viscoelasticity of starch gel before and after healing with shear frequency.

[0057] Figure 4 The graph shows the change in viscoelasticity of starch gel before and after healing with shear stress.

[0058] Figure 5 Graph showing the variation of injection pressure for starch gel plugging in core samples with different fracture openings;

[0059] Figure 6 for Figure 5 Enlarged view of a single water drive stage. Detailed Implementation

[0060] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0061] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0062] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0063] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be obvious to those skilled in the art. This specification and embodiments are merely exemplary.

[0064] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0065] Unless otherwise specified, "room temperature" in this invention refers to 15-30℃.

[0066] Basic Example: Preparation Method of Pregelatinized Starch-Based Gelatin Blocking Agent

[0067] The process includes the following steps: Pre-stirring water in a device equipped with a stirrer at 300-400 rpm; then adding modified starch to the water and stirring for 30-45 minutes at 300-400 rpm until the modified starch is completely gelatinized and thickened in the water; adding an amide compound and continuing stirring for 5-10 minutes at 300-400 rpm; then adding a crosslinking agent and stirring for 5-10 minutes until completely dissolved at 300-400 rpm; finally adding a high-temperature stabilizer, initiator, and oxygen scavenger, stirring for 15-20 minutes until completely dissolved at 300-400 rpm, and aging in a constant temperature oven at 130°C until complete gelation, to obtain the pregelatinized starch-based gel plugging agent.

[0068] Based on the breakthrough pressure simulation of a 1m long sand-filled tube, a pregelatinized starch-based gel sample prepared by injecting 0.5PV was used. The sand-filled tube model was aged at a specified temperature until the pregelatinized starch-based gel sample was completely gelled. The permeability was measured, and the breakthrough pressure was subsequently measured by water drive.

[0069] Example 1:

[0070] The process includes the following steps: Pre-stirring water in a device equipped with a stirrer at 350 rpm; then adding 4% carboxymethyl cassava starch to the water and stirring for 40 minutes at 350 rpm until the modified starch is completely gelatinized and thickened in the water; adding 4% acrylamide monomer and stirring for another 8 minutes at 350 rpm; then adding 0.1% N,N-dimethylacrylamide and stirring for 8 minutes until completely dissolved at 350 rpm; finally adding 0.05% potassium persulfate, 0.1% sodium sulfite, and 0.1% benzoyl peroxide, stirring for 18 minutes until completely dissolved at 350 rpm, and aging in a constant temperature oven at 130°C until complete gelation, yielding the pregelatinized starch-based gel blocker.

[0071] Example 2:

[0072] The process includes the following steps: Pre-stirring water in a device equipped with a stirrer at 350 rpm; then adding 3.5% carboxymethyl cassava starch to the water and stirring for 40 minutes at 350 rpm until the modified starch is completely gelatinized and thickened in the water; adding 3.5% acrylamide monomer and stirring for another 8 minutes at 350 rpm; then adding 0.2% N,N-dimethylacrylamide and stirring for 8 minutes until completely dissolved at 350 rpm; finally adding 0.01% potassium persulfate, 0.1% sodium sulfite, and 0.2% benzoyl peroxide, stirring for 18 minutes until completely dissolved at 350 rpm, and aging in a constant temperature oven at 130°C until complete gelation, yielding the pregelatinized starch-based gel blocker.

[0073] Example 3:

[0074] The process includes the following steps: Pre-stirring water in a device equipped with a stirrer at 350 rpm; then adding 3% carboxymethyl cassava starch to the water and stirring for 40 minutes at 350 rpm until the modified starch is completely gelatinized and thickened in the water; adding 3% acrylamide monomer and stirring for another 8 minutes at 350 rpm; then adding 0.15% N,N-dimethylacrylamide and stirring for 8 minutes until completely dissolved at 350 rpm; finally adding 0.05% potassium persulfate, 0.1% sodium sulfite, and 0.15% benzoyl peroxide and stirring for 18 minutes until completely dissolved at 350 rpm; and then aging the mixture in a constant temperature oven at 130°C until complete gelation, thus obtaining the pregelatinized starch-based gel blocker.

[0075] Example 4:

[0076] The process includes the following steps: Pre-stirring water in a device equipped with a stirrer at 350 rpm; then adding 3% carboxymethyl cassava starch to the water and stirring for 40 minutes at 350 rpm until the modified starch is completely gelatinized and thickened in the water; adding 3% acrylamide monomer and stirring for another 8 minutes at 350 rpm; then adding 0.1% N,N-dimethylacrylamide and stirring for 8 minutes until completely dissolved at 350 rpm; finally adding 0.05% potassium persulfate, 0.1% sodium sulfite, and 0.1% benzoyl peroxide, stirring for 18 minutes until completely dissolved at 350 rpm, and aging in a constant temperature oven at 130°C until complete gelation, yielding the pregelatinized starch-based gel blocker.

[0077] Comparative Example 1

[0078] The difference from Example 1 is that the high-temperature stabilizer benzoyl peroxide is not added, while the other steps and operations are the same as in Example 1.

[0079] Example 1 of effect verification

[0080] Comparing the self-healing pregelatinized starch-based gels prepared in Example 1 and Comparative Example 1, it was found that when the modified starch gel system contained only initiators and oxygen scavengers, the three-dimensional network structure of the gel system gradually loosened under the continuous erosion of the high-temperature environment, and the interconnections between the molecular chains also became sparse and diffused. Therefore, in addition to initiators and oxygen scavengers, high-temperature stabilizers also need to be added to the self-healing pregelatinized starch-based gel. Under the same ambient temperature conditions, the SEM microstructure showed a more compact and dense network structure, with molecules mutually associating and entangled, stably maintaining the interconnected chemical bonds, thus enhancing the stability of the gel structure. (See [link to SEM microstructure]). Figure 1 .

[0081] Example 2 of effect verification

[0082] The results of Example 1, a validation study, indicate that Example 1 represents the optimal mass fractions of each component required for the synthesis of the gel system. To further investigate the self-healing properties of this gel system, the gelled block structure was removed and placed in a petri dish to disperse the sample. Changes in the gel structure were observed using a polarizing microscope, and its rheological properties were analyzed. Based on the fact that the main functional group of the gel structure is a hydrophilic carboxyl group containing numerous hydrogen bonds, these hydrogen bonds provide strong reversible interlocking in the three-dimensional network space of the gel after the formation of the fracture surface. Under dynamic cross-linking, topological recombination occurs, forming new hydrophilic carboxyl groups and diffusing new hydrogen bonds, supporting the self-healing ability of the network structure, repairing the broken fracture surface, and maintaining the viscoelasticity and adhesiveness of the gel system. Therefore, the changes in the viscoelasticity of the gel system before and after the reaction are not significant. Figure 2 , Figure 3 and Figure 4 .

[0083] Example 3 of effect verification

[0084] 0.5 PV of the pregelatinized starch-based gel prepared in Example 1 was injected into a sand-filled tube with a permeability of 3235 mD and a diameter of 100 cm at a flow rate of 2 mL / min. Subsequently, the sand-filled tubes with different gel systems were placed in a constant temperature aging chamber for coagulation. Water was injected from the inlet end at a flow rate of 5 mL / min until the pressure reached the highest point and then suddenly dropped, with the breakthrough pressure reaching 20.25 MPa.

[0085] Example 4 of effect verification

[0086] Given the unique formation conditions of fractured-vuggy carbonate reservoirs in the Tarim Oilfield, fractured cores with a matrix permeability of less than 0.01 mD were designed. Reservoir fluid flow primarily occurs through fracture channels of varying developmental forms. Core plugging tests were conducted on physical models of fractured cores with different fracture widths. 0.5 PV gel was injected at a flow rate of 1 mL / min. After aging, 1.5 PV was water-driven at the same flow rate of 1 mL / min. The experimental results are shown in Table 1 and [Table data would be inserted here]. Figure 5 , Figure 6 .

[0087] Table 1. Basic parameters and experimental data of fractured core samples

[0088]

[0089] Examples 1-4 demonstrate that the pregelatinized starch-based gel plugging agent prepared in this invention utilizes reversible dynamic diffusion hydrogen bonds to re-entwine and associate the gel structure molecular chains, repairing damaged fracture surfaces. It exhibits high strength and good plugging performance. The hydrolyzed modified starch and acrylamide combine in aggregate form and grow randomly, forming a three-dimensional network structure. As the reaction proceeds, the structural units are completely cross-linked, and the residual resistance coefficient of the starch gel system remains unchanged until the reaction is complete. In the application of enhanced oil recovery in the petroleum industry, it demonstrates excellent deep migration capability, strong shear resistance, good selective plugging, and extremely strong plugging ability.

Claims

1. A pregelatinized starch-based gel breaker characterized by: by weight percentage comprising the following components: Modified starch: 3-4 wt%; Amide compound: 3-4 wt%; Crosslinking agent: 0.1-0.2 wt%; Initiator: 0.05-0.1 wt%; High-temperature stabilizer: 0.1-0.2 wt%; Deoxidizer: 0.1-0.2 wt%; Water: the balance.

2. The pregelatinized starch-based gel breaker of claim 1, wherein: by weight percentage comprising the following components: Modified starch: 4 wt%; Amide compound: 4 wt%; Crosslinking agent: 0.1 wt%; Initiator: 0.05 wt%; High-temperature stabilizer: 0.1 wt%; Deoxidizer: 0.1 wt%; Water: the balance.

3. The pregelatinized starch-based gel breaker of claim 1, wherein: The modified starch is selected from one or more of carboxymethyl wheat starch, carboxymethyl tapioca starch and carboxymethyl potato starch.

4. The pregelatinized starch-based gel breaker of claim 3, wherein: The modified starch is carboxymethyl tapioca starch.

5. The pregelatinized starch-based gel breaker of claim 1, wherein: The amide compound is acrylamide monomer.

6. The pregelatinized starch-based gel breaker of claim 1, wherein: The crosslinking agent is selected from one or more of N,N-dimethyl acrylamide, N,N-dimethyl acetamide, methylene bisacrylamide and N,N-methylene bisacrylamide.

7. The pregelatinized starch-based gel breaker of claim 6, wherein: The crosslinking agent is N,N-dimethyl acrylamide.

8. The pregelatinized starch-based gel breaker of claim 1, wherein: The initiator is selected from one or more of sodium persulfate, potassium persulfate and ammonium persulfate.

9. The pregelatinized starch-based gel breaker of claim 8, wherein: The initiator is potassium persulfate.

10. The pregelatinized starch-based gel breaker of claim 1, wherein: The high-temperature stabilizer is selected from one or more of benzoyl peroxide, dibenzoyl peroxide and cumene hydroperoxide.

11. The pregelatinized starch-based gel breaker of claim 10, wherein: The high-temperature stabilizer is benzoyl peroxide.

12. The pregelatinized starch-based gel breaker of claim 1, wherein: The deoxidizer is selected from one or more of sodium sulfite, amine sulfite and sodium bisulfite.

13. The pregelatinized starch-based gel breaker of claim 12, wherein: The deoxidizer is sodium sulfite.

14. A process for the preparation of pregelatinized starch based gelatinization blocking agent according to any one of claims 1 to 13, characterized in that: The method comprises the following steps: pre-stirring water in a device with a stirrer; then adding modified starch to the water, after the modified starch is completely gelatinized and thickened in the water, adding an amide compound and continuing to stir, then adding a crosslinking agent and stirring until it is completely dissolved; finally adding a high-temperature stabilizer, an initiator and a deoxidizer, stirring until they are completely dissolved, placing them in an incubator for aging until they are completely gelled, to obtain the pre-gelatinized starch-based gel plugging agent.

15. The method of claim 14, wherein: The stirring speed is always 300-400 rpm; the stirring time after adding the modified starch is 30-45 min; the stirring time after adding the amide compound is 5-10 min; the stirring time after adding the crosslinking agent is 5-10 min; and the stirring time after adding the high-temperature stabilizer, the initiator and the deoxidizer is 15-20 min.

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