CN116120913A - Self-degrading solid particle type sinking agent and preparation method thereof - Google Patents

Abstract

The invention discloses a self-degrading solid particle type sinking agent and a preparation method thereof, which solve the problems that the self-degrading solid particle type sinking agent cannot be degraded after an artificial interlayer is formed in the prior art, has larger damage to storage and isolation, cannot be basically treated in underground accidents, and a bulk rubber plug type sinking agent material can not meet shielding requirements, and the like, and comprises the following components in mass fraction: 25-45% of weighting agent, 8-12% of consolidation agent, 0.008-0.036% of initiator, 0.01-0.05% of cross-linking agent, 6-8% of suspending agent and 0.01-0.03% of degradation agent; the balance being water. Through the scheme, the invention has the advantages of strong reliability, simple preparation process and the like, and has high practical value and popularization value in the technical field of artificial interlayer seam control high sinking agent materials.

Description

Self-degrading solid particle type sinking agent and preparation method thereof

Technical Field

The invention relates to the technical field of artificial interlayer seam control high sinking agent materials in an acid fracturing technology, in particular to a self-degrading solid particle type sinking agent and a preparation method thereof.

Background

The carbonate rock oil and gas reservoirs in China are very widely distributed, and have great potential for exploration and development. However, due to the fact that the heterogeneity of the carbonate reservoir is strong and the geological conditions are complex, the development condition of a fracture-cavity system of the carbonate reservoir cannot be described precisely by the existing geophysical prospecting technology, and drilling can only reach the vicinity of a fracture-cavity development favorable region predicted by earthquake, so that a certain difficulty is brought to the development of the carbonate reservoir. In general, a carbonate reservoir needs to be reformed through the reservoir to achieve the purposes of knowing the reservoir and increasing the production in the reservoir, and the acidizing and fracturing reformation of the reservoir becomes a key technology for efficiently developing the carbonate.

Aiming at the acid fracturing technology of deep carbonate reservoirs, the acid fracturing technology suitable for fracture (karst cave) reservoir characteristics is basically formed, corresponding fracturing fluid, acid fluid systems and formulas are developed and developed, the acid fracturing technology mainly comprising multistage alternate injection of acid fracturing and pre-hydraulic acid fracturing is formed, and the matched technologies of construction pipe column optimization design, wellhead construction pressure reduction, rapid flowback after pressure and the like are formed, so that the acid fracturing construction success rate is improved year by year, but the effective rate of measures is unsatisfactory. Among them, the high control difficulty of seam, easy communication of bottom water leads to acid fracturing failure to be an important reason. The artificial baffle layer is formed by adding the baffle material in the acid fracturing process, so that the longitudinal extension of cracks can be effectively restrained, the transformation effect, the construction success rate and the development efficiency of the carbonate reservoir can be improved, and the method has a certain guiding value for on-site acid fracturing transformation.

The artificial interlayer seam control height sinking agent material is roughly divided into: inorganic granular sinking agent, solidified artificial interlayer material and liquid rubber plug type sinking agent material. The inorganic granular sinking agent has the advantages that various parameters of quartz sand and powder pottery are close and the properties of the quartz sand and the powder pottery are similar, and the quartz sand and the powder pottery have certain permeability after forming an artificial interlayer, but the joint control capability is weaker due to pressure transmission, and underground accidents such as sand blockage are difficult to effectively treat. The cured artificial interlayer material has weak anti-impact and anti-dilution capability, and influences the construction of an artificial interlayer. In addition, even after the artificial interlayer is formed, the artificial interlayer cannot be degraded, has large damage to the storage and isolation, and cannot be basically treated in underground accidents. The liquid rubber plug type sinking agent material has limited anti-impact capability, high-temperature and high-pressure reservoir, underground crosslinking becomes more difficult to control, and the liquid rubber plug material has poor high-temperature resistance and salt resistance and may not meet shielding requirements.

Therefore, there is an urgent need to provide a self-degrading solid particle type sinking agent with strong reliability and simple preparation process.

Disclosure of Invention

Aiming at the problems, the invention aims to provide a self-degrading solid particle type sinking agent and a preparation method thereof, and the technical scheme adopted by the invention is as follows:

a self-degrading solid particle type sinking agent, which comprises the following components in percentage by mass: 25-45% of weighting agent, 8-12% of consolidation agent, 0.008-0.036% of initiator, 0.01-0.05% of cross-linking agent, 6-8% of suspending agent and 0.01-0.03% of degradation agent; the balance being water.

Further, the weighting agent is one of barite, superfine heavy calcium carbonate powder and calcium sulfate.

Further, the initiator is two of ammonium persulfate, sodium bisulfite, potassium persulfate, ferrous chloride, hydrogen peroxide and formaldehyde sodium bisulfite.

Preferably, the cross-linking agent is one or two of aluminum citrate, chromium acetate, formaldehyde and phenol.

Preferably, the degradation agent is a microcapsule breaker.

Preferably, the suspending agent is one of superfine montmorillonite and bentonite.

A method for preparing a self-degrading solid particle type sinking agent, which comprises the following steps:

adding 8-12% of a consolidation agent into deionized water, and fully stirring and dissolving; after the consolidation agent is completely dissolved, adding 25-45% of weighting agent, stirring, and simultaneously adding 6-8% of suspending agent, and fully dissolving to obtain a first suspension intermediate product;

adding a solution of a cross-linking agent with the concentration of 5% into the first suspension intermediate product according to the dosage of 0.01% -0.05%, adding a degradation agent with the concentration of 0.01% -0.03%, and carrying out ultrasonic oscillation for 5 minutes to obtain a second intermediate product;

adding a solution of an initiator with the concentration of 2% into the second intermediate product according to the dosage of 0.01% -0.05%, uniformly stirring, and placing the mixture into a water bath with the temperature of 50 ℃ for initiation;

and after the gel crosslinking initiation is completed, shearing the gel blocks, drying at 90 ℃ for 4 hours, crushing, screening by a screen, and obtaining the acid pressure controlled seam high self-degradation sinking agent.

Preferably, the screen mesh is 70-140 meshes.

Further, the density and the particle size of the acid fracturing seam-control high self-degradation sinking agent meet the following formula:

indicating the density of the clean liquid of the carrying liquid, kg/m ³ ；/>

Represents the gravity settling velocity, m/s, of the single-particle sinking agent; />

Represents the particle diameter, m, of the sinking agent; />

Indicating the bulk density of the sinking agent, kg/m ³ ；/>

The apparent viscosity of the carrier fluid is expressed in Pa ∙ s;crepresenting the volume percent (decimal) of the sinking agent in the carrying fluid.

Preferably, the preparation process of the degradation agent is as follows:

step S1, 1g of acrylonitrile-butadiene-styrene copolymer of a shell material is dissolved in 30mL of methylene dichloride solution at room temperature, 0.5g of ammonium persulfate powder is weighed and dispersed in the polymer dispersion liquid under the stirring speed of 350rpm to obtain mixed dispersion liquid;

step S2, slowly and dropwise adding 20mL of polydimethylsiloxane oil into the mixed dispersion liquid to obtain a mixture;

step S3, pouring the mixture into a round bottom three-neck flask which is filled with 250mL of n-heptane and provided with a condensing device, stirring for 30min at a stirring speed of 450rpm, and solidifying the microcapsules;

step S4, heating the mixture in the step S3 at 40 ℃ for 1h to separate and recycle dichloromethane; stopping stirring and depositing for 30min; washing with 100mL of n-heptane and 50mL of deionized water for three times respectively, and drying at 40 ℃;

and S5, separating n-heptane from the polydimethylsiloxane oil by adopting a distillation method so as to obtain the degradation agent for recycling.

Compared with the prior art, the invention has the following beneficial effects:

(1) The invention is characterized in that the powder is prepared by drying the synthetic gel-like gel block, so that the density and the grain size range of the powder can be regulated and controlled, the density and the grain size range of the sinking agent can be regulated, the degradation agent can be automatically degraded by breaking gel in a high-temperature target layer, and residual acid can react with part of materials, thereby reducing the damage to a storage layer.

(2) The sinking agent can absorb water and swell along with the process that the carrying liquid enters the target layer, and the particles can be solidified to form a denser artificial barrier layer when the sinking agent is subjected to sedimentation compaction. After the acid fracturing construction is completed, the sinking agent material can react with residual acid after the acid fracturing, the sinking agent material can be self-degraded, the residual material can avoid complete closure of cracks, and a permeable channel formed by acid etching of the residual acid can be formed after the acid fracturing is finished.

In conclusion, the invention has the advantages of strong reliability, simple preparation process and the like, and has high practical value and popularization value in the technical field of artificial interlayer seam control high sinking agent materials.

Drawings

For a clearer description of the technical solutions of the embodiments of the present invention, the drawings to be used in the embodiments will be briefly described below, it being understood that the following drawings only illustrate some embodiments of the present invention and should not be considered as limiting the scope of protection, and other related drawings may be obtained according to these drawings without the need of inventive effort for a person skilled in the art.

FIG. 1 is a graph of sedimentation velocity versus viscosity for the present invention.

FIG. 2 is a comparison of the self-degrading examples of the present invention ((a) the degraded solids content of example 1, (b) the degraded solids content of example 2, and (c) the degraded solids content of example 3).

Detailed Description

For the purposes, technical solutions and advantages of the present application, the present invention will be further described with reference to the accompanying drawings and examples, and embodiments of the present invention include, but are not limited to, the following examples. All other embodiments, which can be made by one of ordinary skill in the art without undue burden from the present disclosure, are within the scope of the present application based on the embodiments herein.

In this embodiment, the term "and/or" is merely an association relationship describing the association object, and indicates that three relationships may exist, for example, a and/or B may indicate: a exists alone, A and B exist together, and B exists alone.

The terms first and second and the like in the description and in the claims of the present embodiment are used for distinguishing between different objects and not for describing a particular sequential order of objects. For example, the first target object and the second target object, etc., are used to distinguish between different target objects, and are not used to describe a particular order of target objects.

In the embodiments of the present application, words such as "exemplary" or "such as" are used to mean serving as examples, illustrations, or descriptions. Any embodiment or design described herein as "exemplary" or "for example" should not be construed as preferred or advantageous over other embodiments or designs. Rather, the use of words such as "exemplary" or "such as" is intended to present related concepts in a concrete fashion.

In the description of the embodiments of the present application, unless otherwise indicated, the meaning of "a plurality" means two or more. For example, the plurality of processing units refers to two or more processing units; the plurality of systems means two or more systems.

The technology provides a self-degrading solid particle type sinking agent and a preparation method thereof, wherein the sinking agent can enter a target layer along with carrying liquid and is subjected to sedimentation compaction in cracks; the particles can deform in the sedimentation compaction process to form a more compact artificial barrier layer. The degradation agent (microcapsule gel breaker) contained in the sinking agent can enable the sinking agent to break gel and degrade automatically in a certain time under the high-temperature condition of the reservoir. And the self-degradation performance of the sinking agent can solve the construction accident of sand blockage in a high-temperature high-pressure reservoir. Residues after the post construction are completed can avoid complete closure of cracks, and permeable crack channels generated by acid etching of residual acid can be formed.

In this embodiment, the sinking agent is composed of the following components in mass fraction: 25-45% of weighting agent, 8-12% of consolidation agent, 0.008-0.036% of initiator, 0.01-0.05% of cross-linking agent, 6-8% of suspending agent, 0.01-0.03% of degradation agent and water. Wherein the weight adding agent is one of barite, superfine heavy calcium carbonate powder and calcium sulfate; the initiator is two of ammonium persulfate, sodium bisulphite, potassium persulfate, ferrous chloride, hydrogen peroxide and formaldehyde sodium bisulphite; the cross-linking agent is one or two of aluminum citrate, chromium acetate, formaldehyde and phenol; the degradation agent is a microcapsule gel breaker; the suspending agent is one of superfine montmorillonite and bentonite.

In this embodiment, the chemical reaction process is involved in the preparation process of the self-degrading solid particle type sinking agent, which is a free radical polymerization reaction, and since the several reagents have the same effect, in order to simplify the reaction process, a is used to refer to a consolidation agent (one of acrylamide and ethyl acetate), B is used to refer to an initiator (two of ammonium persulfate, sodium bisulfate, potassium persulfate, ferrous chloride, hydrogen peroxide and sodium metabisulfite), C is used to refer to a crosslinking agent (one or two of aluminum citrate, chromium acetate, formaldehyde and phenol), and the rest of weighting agents and suspending agents do not participate in the reaction due to physical effects, and the reaction process is as follows:

wherein, the preparation process is as follows:

(1) Firstly, adding a consolidation agent into deionized water with a proper volume, and uniformly stirring to fully dissolve the consolidation agent; after the consolidation agent is completely dissolved, adding a weighting agent (insoluble), and then slowly and slightly adding a suspending agent under the condition of stirring by a stirrer, so that the suspending agent is fully dissolved in the solution, wherein the mass component ranges of the three medicaments are as follows: 25-45%, 8-12%, 6-8% of a first suspension intermediate product is formed;

(2) Adding a solution with the concentration of 5% of the cross-linking agent, wherein the adding amount of the cross-linking agent is 0.1% -0.3% of the dosage of the consolidation agent, adding the cross-linking agent into the first suspension intermediate product, and forming a second intermediate product after ultrasonic oscillation for 5 minutes;

(3) Preparing an initiator into a solution with the concentration of 2%, wherein the addition range of the initiator is 0.01% -0.05%; adding the initiator solution into the second intermediate product, uniformly stirring, and directly placing into a water bath at 50 ℃ for initiation;

(4) And after the gel crosslinking initiation is completed, shearing the gel blocks, drying at 90 ℃ for 4 hours, taking out the gel blocks to be smashed in a smashing machine, and screening out the target particle size by using a screen mesh to obtain the acid pressure controlled seam high self-degradation sinking agent.

In addition, the degradation agent of the embodiment is a microcapsule gel breaker, and the preparation process is as follows:

(1) 1g of the shell material acrylonitrile-butadiene-styrene copolymer was dissolved in 30mL of methylene chloride solution (three-necked flask) at room temperature, and then 0.5g of the core material (ammonium persulfate powder) was weighed and dispersed in the above polymer dispersion at a stirring rate of 350 rpm.

(2) 20mL of polydimethylsiloxane oil was slowly added dropwise to the above mixed dispersion.

(3) Curing of the microcapsules: after the completion of the addition of the polydimethyl silicone oil, the mixture was rapidly poured into a round bottom three-necked flask equipped with 250mL of n-heptane and equipped with a condensing device, and stirred at a stirring rate of 450rpm for 30min, to effect the solidification of the microcapsules.

(4) And (3) collection of microcapsules: the mixture in 3 was heated at 40℃for 1h to separate and recover dichloromethane. The stirring was stopped and the microcapsules were allowed to settle for 30min. The mixture was separated, washed three times with 100mL of n-heptane and 50mL of deionized water, and dried at 40 ℃.

(5) In the above filtrate, n-heptane was separated from the polydimethyl silicone oil by distillation for recycling.

To verify the feasibility of the technology, the following embodiments are specifically listed:

example 1

The composition of the self-degrading solid particle type sinking agent of this example is as follows: 25% of barite powder, 8% of acrylamide, 0.008% of ammonium persulfate, 0.008% of sodium bisulphite, 0.01% of aluminum citrate, 0.01% of capsule gel breaker, 6% of superfine montmorillonite and the balance of water.

The preparation method of the self-degrading solid particle type sinking agent comprises the following steps:

(1) Dissolving acrylamide in the consolidation agent in deionized water with proper volume, uniformly stirring to dissolve the acrylamide, and then adding barite powder in the weighting agent; then adding a small amount of superfine montmorillonite in the suspending agent slowly under the stirring condition of a stirrer to fully dissolve the superfine montmorillonite in the solution, wherein the mass ratio of the three agents is 25:8:6, and forming a first suspending liquid intermediate product of the main agent.

(2) Aluminum citrate in the cross-linking agent is prepared into a solution with the concentration of 5%, then 0.2ml of cross-linking solution is added into the first suspension intermediate product, then 0.01g of capsule gel breaker is added, and after ultrasonic oscillation is carried out for 5 minutes, a second intermediate product is formed.

(3) Preparing 2% oxidation initiator and reduction initiator solution from ammonium persulfate and sodium bisulphite in the initiator; and then respectively adding 0.4mL of oxidation initiator and reduction initiator solution into the second intermediate product for oxidation reduction initiation, stirring uniformly, and directly placing into a water bath at 50 ℃.

(4) And after the polymer crosslinking initiation is completed, shearing the rubber blocks, drying at 90 ℃ for 4 hours, taking out the rubber blocks to be smashed in a smashing machine, and screening out the target particle size by using a vibrating screen to obtain the acid pressure controlled seam high self-degradation sinking agent.

Example 2

The composition of the self-degrading solid particle type sinking agent of this example is as follows: 35% of superfine heavy calcium carbonate powder, 10% of acrylamide, 0.02% of potassium persulfate, 0.02% of ferrous chloride, 0.03% of chromium acetate, 0.02% of capsule gel breaker, 7% of superfine montmorillonite and the balance of water.

The preparation method of the self-degrading solid particle type sinking agent comprises the following steps:

(1) Dissolving acrylamide in the consolidation agent in deionized water with proper volume, uniformly stirring to dissolve the acrylamide, and then adding superfine heavy calcium carbonate powder in the weighting agent; then adding a small amount of superfine montmorillonite in the suspending agent slowly under the stirring condition of a stirrer to fully dissolve the superfine montmorillonite in the solution, wherein the mass ratio of the three agents is 35:10:7, so as to form a first suspending liquid intermediate product of the main agent;

(2) Preparing chromium acetate in the cross-linking agent into a solution with the concentration of 5%, adding 0.6ml of cross-linking solution into the first suspension intermediate product, adding 0.02g of capsule gel breaker, and performing ultrasonic oscillation for 5 minutes to form a second intermediate product;

(3) Preparing potassium persulfate and ferrous chloride in an initiator into an oxidation initiator solution and a reduction initiator solution with the concentration of 2%; respectively adding 1mL of oxidation initiator and reduction initiator solution into the second intermediate product for oxidation reduction initiation, stirring uniformly, and directly placing into a water bath at 50 ℃;

(4) And after the polymer crosslinking initiation is completed, shearing the rubber blocks, drying at 90 ℃ for 4 hours, taking out the rubber blocks to be smashed in a smashing machine, and screening out the target particle size by using a vibrating screen to obtain the acid pressure controlled seam high self-degradation sinking agent.

Example 3

The composition of the self-degrading solid particle type sinking agent of this example is as follows: 45% of calcium sulfate, 12% of ethyl acetate, 0.036% of hydrogen peroxide, 0.036% of white suspended block, 0.05% of formaldehyde, 0.05% of phenol, 0.03% of capsule gel breaker, 8% of bentonite and the balance of water.

The preparation method of the self-degrading solid particle type sinking agent comprises the following steps:

(1) Dissolving ethyl acetate in the consolidation agent in deionized water with proper volume, uniformly stirring to dissolve the ethyl acetate, and then adding calcium sulfate in the weighting agent; slowly and slightly adding bentonite in the suspending agent under the stirring condition of a stirrer to enable the bentonite to be fully dissolved in the solution, wherein the mass ratio of the three agents is 45:12:8, so as to form a first suspension intermediate product of the main agent;

(2) Preparing formaldehyde and phenol in the cross-linking agent into a solution with the concentration of 5%, adding 1ml of cross-linking solution into the first suspension intermediate product, adding 0.03g of gel breaker, and performing ultrasonic oscillation for 5 minutes to form a second intermediate product;

(3) Preparing an oxidation initiator solution and a reduction initiator solution with the concentration of 2% from hydrogen peroxide and a suspended white block in an initiator; respectively adding 1.8mL of oxidation initiator and reduction initiator solution into the second intermediate product for oxidation reduction initiation, uniformly stirring, and directly placing into a water bath at 50 ℃;

(4) And after the polymer crosslinking initiation is completed, shearing the rubber blocks, drying at 90 ℃ for 4 hours, taking out the rubber blocks to be smashed in a smashing machine, and screening out the target particle size by using a vibrating screen to obtain the acid pressure controlled seam high self-degradation sinking agent.

Test example 1

1) Setting the viscosity of the carrying liquid to be 1, 5, 10, 15, 20 and 25mPa ∙ s, pouring the carrying liquid into a prepared test tube, and ensuring the liquid height to be 9cm;

2) Weighing a sinking agent particle sample according to the volume of carrying liquid and the sand ratio of 10%, pouring the sinking agent particles into a measuring cylinder, wetting and stirring by using a glass rod, and recording the time when the sample is wetted and begins to subside; shooting the sedimentation condition of the sinking agent once in real time, and stopping observing when the sinking agent particles in the cup are basically completely settled or the total sedimentation exceeds 20 minutes.

The measurement results are shown in fig. 1, and it can be seen from fig. 1 that the sedimentation velocity of example 1 is centered, the sedimentation velocity of example 2 is the slowest, and the sedimentation velocity of example 3 is the fastest. The sedimentation velocity of the sinking agent particles in the sedimentation process cannot be too fast or too slow, and a proper value is needed, and the image shows that the sedimentation velocity is optimal at the liquid viscosity of 5-10 mPa ∙ s and is 0.34-0.93 cm/s.

Test example 2

1) The experiment utilizes a high-temperature autoclave, 3 groups of 100ml gelled acid residual acid gel breaking liquid containing 5% concentration acid pressure self-degradation sinking agent (5 g) are respectively prepared in a beaker, and the solutions are respectively poured into 6 high-temperature autoclaves;

2) And (3) placing the mixture into a roller furnace after sealing, rotating and uniformly heating the mixture to perform high-temperature degradation, wherein the temperature is set to 160 ℃, the degradation time is 12 hours, and finally taking the mixture out of the reaction kettle after 12 hours to observe the self-degraded solid content of the mixture.

The test results are shown in FIG. 2, in which the post-self-degradation solid content is relatively moderate (2.8 g) in example 1 (FIG. 2 (a)), and the post-self-degradation solid content is the highest (3.2 g) in example 3 (FIG. 2 (c)) in example 2 (FIG. 2 (b)) because the weighting agent is ultra-fine ground calcium carbonate and is substantially completely self-degraded (0.8 g). Therefore, the self-degradable material in the embodiment 1 has moderate quality, can ensure lower crack closure and diversion capability after acid fracturing is finished, can reduce the risk of communicating a water layer, and is suitable for acid fracturing self-degradable materials; example 2 has the advantages that the self-degraded material has the minimum quality, the crack flow conductivity is higher after acid fracturing is finished, and the risk of communicating a water layer is higher; example 3 the mass of the material after self-degradation was maximized. Considering that too much material is harmful to the reservoir after self-degradation, example 1 is preferred as an acid fracturing self-degradation sinker material formulation.

The above embodiments are only preferred embodiments of the present invention and are not intended to limit the scope of the present invention, but all changes made by adopting the design principle of the present invention and performing non-creative work on the basis thereof shall fall within the scope of the present invention.

Claims (10)

1. The self-degrading solid particle type sinking agent is characterized by comprising the following components in percentage by mass: 25-45% of weighting agent, 8-12% of consolidation agent, 0.008-0.036% of initiator, 0.01-0.05% of cross-linking agent, 6-8% of suspending agent and 0.01-0.03% of degradation agent; the balance being water.

2. The self-degrading solid particulate sinking agent as claimed in claim 1, wherein the weighting agent is one of barite, superfine heavy calcium carbonate powder and calcium sulfate.

3. The self-degrading solid particulate type sinking agent according to claim 1 or 2, wherein the initiator is two of ammonium persulfate, sodium bisulfite, potassium persulfate, ferrous chloride, hydrogen peroxide and formaldehyde sodium bisulfite.

4. A self-degrading solid particulate sinking agent according to claim 1 or 2, wherein the cross-linking agent is one or two of aluminium citrate, chromium acetate, formaldehyde and phenol.

5. A self-degrading solid particulate sinking agent according to claim 1 or 2, wherein the degrading agent is a microcapsule breaker.

6. A self-degrading solid particulate sinking agent according to claim 1 or 2, wherein the suspending agent is one of ultra-fine montmorillonite and bentonite.

7. A method for preparing the self-degrading solid particle type sinking agent according to any one of claims 1 to 6, comprising the following steps:

adding 8-12% of a consolidation agent into deionized water, and fully stirring and dissolving; after the consolidation agent is completely dissolved, adding 25-45% of weighting agent, stirring, and simultaneously adding 6-8% of suspending agent, and fully dissolving to obtain a first suspension intermediate product;

adding a solution of a cross-linking agent with the concentration of 5% into the first suspension intermediate product according to the dosage of 0.01% -0.05%, adding a degradation agent with the concentration of 0.01% -0.03%, and carrying out ultrasonic oscillation for 5 minutes to obtain a second intermediate product;

adding a solution of an initiator with the concentration of 2% into the second intermediate product according to the dosage of 0.01% -0.05%, uniformly stirring, and placing the mixture into a water bath with the temperature of 50 ℃ for initiation;

and after the gel crosslinking initiation is completed, shearing the gel blocks, drying at 90 ℃ for 4 hours, crushing, and screening by adopting a screen to obtain the acid pressure controlled seam high self-degradation sinking agent.

8. The method for preparing the self-degrading solid particle type sinking agent according to claim 7, wherein the screen is 70-140 meshes.

9. The method for preparing the self-degrading solid particle type sinking agent according to claim 7 or 8, wherein the density and the particle size of the acid fracturing control gap high self-degrading sinking agent meet the following formula:

；

representing the density of the carrier liquid; />

Representing the gravity settling velocity of the single particle sinking agent; />

Represents the particle diameter of the sinking agent; />

Represents the bulk density of the sinking agent; />

Indicating the apparent viscosity of the carrier fluid;crepresenting the volume percentage of the sinking agent in the carrying liquid.

10. The method for preparing the self-degrading solid particle type sinking agent according to claim 7, wherein the preparation process of the degrading agent is as follows:

step S1, 1g of acrylonitrile-butadiene-styrene copolymer of a shell material is dissolved in 30mL of methylene dichloride solution at room temperature, 0.5g of ammonium persulfate powder is weighed and dispersed in the polymer dispersion liquid under the stirring speed of 350rpm to obtain mixed dispersion liquid;

step S2, slowly and dropwise adding 20mL of polydimethylsiloxane oil into the mixed dispersion liquid to obtain a mixture;

step S3, pouring the mixture into a round bottom three-neck flask which is filled with 250mL of n-heptane and provided with a condensing device, stirring for 30min at a stirring speed of 450rpm, and solidifying the microcapsules;

step S4, heating the mixture in the step S3 at 40 ℃ for 1h to separate and recycle dichloromethane; stopping stirring and depositing for 30min; washing with 100mL of n-heptane and 50mL of deionized water for three times respectively, and drying at 40 ℃;

and S5, separating n-heptane from the polydimethylsiloxane oil by adopting a distillation method so as to obtain the degradation agent for recycling.

Images