阅读说明：本技术 强抑制聚束环保钻完井液 (Strong-inhibition bunching environment-friendly drilling and completion fluid ) 是由 孟虎 刘亚东 朱国伟 吴骏峰 于 2019-11-04 设计创作，主要内容包括：本发明公开了一种强抑制聚束环保钻完井液,其包括80～90重量份的基液和10～20重量份的微乳纳米制剂；所述微乳纳米制剂为从内到外依次为氧化型破胶剂、生物酶破胶剂、酸性破胶剂以及囊壳；氧化型破胶剂与生物酶破胶剂、生物酶破胶剂与酸性破胶剂之间通过包覆膜隔离。本发明可将滤壳较彻底的消除,可生物降解返排效果好,无毒避免对油气层的伤害,可最大程度地提高油气井产能和充分保护储层。(The invention discloses a strong-inhibition bunching environment-friendly drilling and completion fluid which comprises 80-90 parts by weight of base fluid and 10-20 parts by weight of microemulsion nano preparation; the micro-emulsion nano preparation comprises an oxidation type gel breaker, a biological enzyme gel breaker, an acid gel breaker and a capsule shell from inside to outside in sequence; the oxidation type gel breaker and the biological enzyme gel breaker, and the biological enzyme gel breaker and the acid gel breaker are isolated by coating films. The invention can thoroughly eliminate the filter casing, has good biodegradable flowback effect, is nontoxic, avoids the damage to an oil-gas layer, can furthest improve the productivity of the oil-gas well and fully protect the reservoir layer.)

1. The environment-friendly drilling completion fluid capable of strongly inhibiting bunching is characterized by comprising 80-90 parts by weight of base fluid and 10-20 parts by weight of microemulsion nano preparation; the micro-emulsion nano preparation comprises an oxidation type gel breaker, a biological enzyme gel breaker, an acid gel breaker and a capsule shell from inside to outside in sequence; the oxidation type gel breaker, the biological enzyme gel breaker and the acid gel breaker are isolated from each other by coating films.

2. The environment-friendly drilling and completion fluid with strong inhibition of bunching as defined in claim 1, wherein the oxidation type gel breaker comprises 3-7 parts by weight of potassium permanganate solution, 0.5-2 parts by weight of magnesium peroxide, 0.1-0.3 part by weight of vegetable oil and 0.03-0.08 part by weight of xanthan gum.

3. The environment-friendly drilling and completion fluid with strong inhibition of bunching as defined in claim 2, wherein the biological enzyme gel breaker comprises 3-8 parts by weight of l,4- β -D-mannase solution, 0.3-0.6 part by weight of glycerol and 0.03-0.08 part by weight of gelatin.

4. The environment-friendly drilling and completion fluid with strong inhibition of bunching as defined in claim 3, wherein the acidic gel breaker comprises β -cyclodextrin in 1-8 parts by weight, citric acid in 5-10 parts by weight, EDTA in 3-8 parts by weight and sodium hypophosphite in 1-6 parts by weight.

5. The environment-friendly drilling completion fluid with strong inhibition of bunching as defined in claim 4, wherein the capsule shell comprises 3-8 parts by weight of xanthan gum, 0.5-0.9 part by weight of acrylic resin L100-55 and 0.3-0.6 part by weight of glycerol.

6. The environment-friendly drilling and completion fluid with strong inhibition of bunching as defined in claim 5, wherein the base fluid comprises water, a polyene polyamine organic acid salt and base oil in a weight ratio of 10:0.4: 2.

7. The environment-friendly drilling and completion fluid with strong inhibition of bunching as defined in claim 6, further comprising 1-3 parts by weight of plugging and anti-collapse agent, 1-3 parts by weight of oil-soluble temporary plugging agent and 0.8-1.2 parts by weight of corrosion inhibitor.

8. The environment-friendly drilling and completion fluid with strong inhibition of bunching as defined in claim 7, wherein the preparation method of the microemulsion nano-preparation comprises the following steps:

s1, weighing 3-7 parts by weight of potassium permanganate solution, 0.5-2 parts by weight of magnesium peroxide, 0.1-0.3 part by weight of vegetable oil and 0.03-0.08 part by weight of xanthan gum, and uniformly mixing to obtain an emulsified oxidized gel breaker; preparing a sodium alginate solution with the mass fraction of 3-4% by using water and sodium alginate, heating to enable the sodium alginate solution to be in a sol state to obtain a sodium alginate colloid, adding an oxidation type gel breaker into the sodium alginate colloid to enable the oxidation type gel breaker to be suspended in the sodium alginate colloid to obtain a suspension, then dropwise adding the suspension into a calcium chloride solution with the mass fraction of 2% by using a dropper, slowly stirring clockwise for 10-15 min, and then pouring out the calcium chloride solution to obtain a core material;

s2, weighing 3-8 parts by weight of a l,4- β -D-mannase solution, 0.3-0.6 part by weight of glycerol and 0.03-0.08 part by weight of gelatin, uniformly stirring to obtain a biological enzyme gel breaker, weighing 1-8 parts by weight of β -cyclodextrin, 5-10 parts by weight of citric acid, 3-8 parts by weight of ethylenediamine tetraacetic acid and 1-6 parts by weight of sodium hypophosphite, dissolving in 10-20 parts by weight of water, uniformly stirring, heating to 80-90 ℃, and continuously stirring for 1-2 hours to obtain an acid gel breaker;

s3, weighing 2-6 parts by weight of gelatin, 0.2-0.6 part by weight of polyethylene glycol, 1-3 parts by weight of white oil and 5-10 parts by weight of water, and fully and uniformly stirring to obtain a coating liquid; weighing 3-8 parts by weight of xanthan gum, 0.5-0.9 part by weight of acrylic resin L100-55, 0.3-0.6 part by weight of glycerol and 20-25 parts by weight of water, and uniformly mixing to obtain a capsule shell;

step S4, equally dividing the coating film liquid into two equal parts, putting the nuclear material obtained in the step S1 into a fluidized bed coating machine, and controlling the air pressure in the fluidized bed coating machine to be 0.2-0.4 MPa and the internal temperature to be 25-35 ℃ so that the nuclear material forms an annular fluidized state; sequentially filling a first coating film liquid, a biological enzyme gel breaker, a second coating film liquid, an acid gel breaker and a capsule shell into a liquid reservoir of a fluidized bed coating machine, sequentially spraying the first coating film liquid, the biological enzyme gel breaker, the second coating film liquid, the acid gel breaker and the capsule shell on a core material through a peristaltic pump to obtain a multi-layer coating, keeping an annular fluidization state for 5-8 min after spraying is completed each time, keeping the annular fluidization state for 60-80 min after spraying of the capsule shell is completed, closing an air compressor, taking out the multi-layer coating, and air-drying to obtain the micro-emulsion nano preparation.

Technical Field

The invention relates to the technical field of oil extraction in oil fields. More particularly, the invention relates to an environment-friendly drilling and completion fluid with strong inhibition of bunching.

Background

In the drilling process, the drilling fluid forms compact inner and outer filter cakes on a well wall to prevent solid phase and liquid phase from invading a reservoir, the existence of the filter cakes greatly reduces the permeability of a near-wellbore area, and the filter cakes are eliminated to the greatest extent before oil gas is put into development; therefore, after drilling and completion, a drilling and completion fluid circulating liquid is introduced into the well and always keeps in contact with an oil gas layer, and in order to protect a reservoir, the drilling and completion fluid should meet the conventional performance (including density, acidity and alkalinity, fluid loss, rheological property, stability and the like), and simultaneously has the characteristics of low toxicity or no toxicity, no harm to the environment and the like.

The conventional drilling and completion fluid is prepared from various raw materials and chemical additives, wherein the conventional drilling and completion fluid contains nondegradable solids or chemical substances with strong corrosivity, and the nondegradable solids are easy to block a throat, so that the oil yield in the oil extraction process is influenced; chemical substances have strong corrosivity and have great damage to underground equipment, pipelines, pump trucks, reservoirs and the like, the function of the gel breaker in the conventional drilling and completing fluid is single, the filtering shell removing effect on the drilling fluid is poor, and effective cleaning of drilling cuttings and suspended matters at the bottom of a well cannot be guaranteed.

Disclosure of Invention

An object of the present invention is to solve at least the above problems and to provide at least the advantages described later.

The invention also aims to provide the strong-inhibition bunching environment-friendly drilling and completion fluid which can thoroughly eliminate a filter casing, has good biodegradable flowback effect, is non-toxic and avoids damage to an oil-gas reservoir, and can improve the productivity of the oil-gas well and fully protect the reservoir to the greatest extent.

To achieve these objects and other advantages in accordance with the present invention, there is provided a strong restraint bunching environment-friendly drilling completion fluid, which includes 80-90 parts by weight of a base fluid and 10-20 parts by weight of a microemulsion nano-formulation; the micro-emulsion nano preparation comprises an oxidation type gel breaker, a biological enzyme gel breaker, an acid gel breaker and a capsule shell from inside to outside in sequence; the oxidation type gel breaker, the biological enzyme gel breaker and the acid gel breaker are isolated from each other by coating films.

Preferably, the strong-inhibition-bunching environment-friendly drilling and completion fluid comprises 3-7 parts by weight of potassium permanganate solution, 0.5-2 parts by weight of magnesium peroxide, 0.1-0.3 part by weight of vegetable oil and 0.03-0.08 part by weight of xanthan gum.

Preferably, the biological enzyme gel breaker comprises 3-8 parts by weight of l,4- β -D-mannase solution, 0.3-0.6 part by weight of glycerol and 0.03-0.08 part by weight of gelatin.

Preferably, the strong-inhibition bunching environment-friendly drilling and completion fluid comprises 1-8 parts by weight of β -cyclodextrin, 5-10 parts by weight of citric acid, 3-8 parts by weight of ethylenediamine tetraacetic acid and 1-6 parts by weight of sodium hypophosphite.

Preferably, the strong-inhibition bunching environment-friendly drilling completion fluid comprises a capsule shell, wherein the capsule shell comprises 3-8 parts by weight of xanthan gum, 0.5-0.9 part by weight of acrylic resin L100-55 and 0.3-0.6 part by weight of glycerol.

Preferably, the strong inhibition bunching environment-friendly drilling and completing fluid comprises water, a polyene polyamine organic acid salt and base oil in a weight ratio of 10:0.4: 2.

Preferably, the environment-friendly drilling and completion fluid capable of strongly inhibiting bunching further comprises 1-3 parts by weight of a plugging anti-collapse agent, 1-3 parts by weight of an oil-soluble temporary plugging agent and 0.8-1.2 parts by weight of a corrosion inhibitor.

Preferably, the preparation method of the microemulsion nano-preparation comprises the following steps:

s1, weighing 3-7 parts by weight of potassium permanganate solution, 0.5-2 parts by weight of magnesium peroxide, 0.1-0.3 part by weight of vegetable oil and 0.03-0.08 part by weight of xanthan gum, and uniformly mixing to obtain an emulsified oxidized gel breaker; preparing a sodium alginate solution with the mass fraction of 3-4% by using water and sodium alginate, heating to enable the sodium alginate solution to be in a sol state to obtain a sodium alginate colloid, adding an oxidation type gel breaker into the sodium alginate colloid to enable the oxidation type gel breaker to be suspended in the sodium alginate colloid to obtain a suspension, then dropwise adding the suspension into a calcium chloride solution with the mass fraction of 2% by using a dropper, slowly stirring clockwise for 10-15 min, and then pouring out the calcium chloride solution to obtain a core material;

s2, weighing 3-8 parts by weight of a l,4- β -D-mannase solution, 0.3-0.6 part by weight of glycerol and 0.03-0.08 part by weight of gelatin, uniformly stirring to obtain a biological enzyme gel breaker, weighing 1-8 parts by weight of β -cyclodextrin, 5-10 parts by weight of citric acid, 3-8 parts by weight of ethylenediamine tetraacetic acid and 1-6 parts by weight of sodium hypophosphite, dissolving in 10-20 parts by weight of water, uniformly stirring, heating to 80-90 ℃, and continuously stirring for 1-2 hours to obtain an acid gel breaker;

s3, weighing 2-6 parts by weight of gelatin, 0.2-0.6 part by weight of polyethylene glycol, 1-3 parts by weight of white oil and 5-10 parts by weight of water, and fully and uniformly stirring to obtain a coating liquid; weighing 3-8 parts by weight of xanthan gum, 0.5-0.9 part by weight of acrylic resin L100-55, 0.3-0.6 part by weight of glycerol and 20-25 parts by weight of water, and uniformly mixing to obtain a capsule shell;

step S4, equally dividing the coating film liquid into two equal parts, putting the nuclear material obtained in the step S1 into a fluidized bed coating machine, and controlling the air pressure in the fluidized bed coating machine to be 0.2-0.4 MPa and the internal temperature to be 25-35 ℃ so that the nuclear material forms an annular fluidized state; sequentially filling a first coating film liquid, a biological enzyme gel breaker, a second coating film liquid, an acid gel breaker and a capsule shell into a liquid reservoir of a fluidized bed coating machine, sequentially spraying the first coating film liquid, the biological enzyme gel breaker, the second coating film liquid, the acid gel breaker and the capsule shell on a core material through a peristaltic pump to obtain a multi-layer coating, keeping an annular fluidization state for 5-8 min after spraying is completed each time, keeping the annular fluidization state for 60-80 min after spraying of the capsule shell is completed, closing an air compressor, taking out the multi-layer coating, and air-drying to obtain the micro-emulsion nano preparation.

The invention at least comprises the following beneficial effects:

1. the invention adopts a microemulsion nano preparation with a multilayer structure, which comprises a plurality of gel breakers, wherein the acidic gel breaker can dissolve drill cuttings and calcium carbonate; the bio-enzyme gel breaker can degrade most polymers into non-reducing monosaccharides and disaccharides; the oxidation type gel breaker can degrade partial polymers, the three gel breakers are sequentially wrapped, the filter cake can be progressively broken and degraded, the oxidation type gel breaker and the biological enzyme gel breaker are isolated by wrapping films, the biological enzyme gel breaker and the acidic gel breaker are prevented from contacting with each other, and the microemulsion nano preparation can progressively eliminate the filter cake;

2. in the process of eliminating the filter cake, the drilling completion fluid firstly degrades the drill cuttings and the calcium carbonate by the acidic gel breaker, and the acid generally has certain corrosivity, so the acidic gel breaker is arranged on the outer layer and is contacted with the complete filter casing, the acidic gel breaker is continuously consumed while the filter casing is broken under the action of the drilling completion fluid, and the reservoir cannot be corroded due to the fact that the acidic gel breaker remains when the filter cake is collapsed; after the acid gel breaker is consumed, the biological enzyme gel breaker is released, most of polymers can be degraded, residues generated in the action process of the acid gel breaker are removed, finally, a small amount of residual polymers are degraded by using the oxidation type gel breaker, and finally, a filter cake is removed to the maximum extent, so that the near-well permeability is improved; the three gel breakers are nontoxic and pollution-free, have strong degradability, can be quickly drained back, cannot cause damage to a reservoir stratum, cannot block a throat, and can be used for laying the working efficiency of later-stage oil extraction; finally, the drilling completion fluid is wrapped by the capsule shell, the capsule shell is broken under the stimulation of a certain condition when the drilling completion fluid is injected into an oil well, the gel breaker is released layer by layer, and the capsule shell can be broken under the self mechanical action of the stratum;

3. according to the invention, citric acid and ethylenediamine tetraacetic acid with weak acidity are selected, so that the problems of over-strong acidity and corrosion to a reservoir are avoided; under the action of sodium hypophosphite, the two acids are attached to the cyclodextrin, so that the two acids can be uniformly dispersed, and the utilization rate of the acidic gel breaker is improved; in the prior art, by adopting a mode of mixing various biological enzymes, not only are the enzymes mutually interfered, but also the produced short refined polysaccharide is crosslinked, so that the short refined polysaccharide cannot be thoroughly degraded, and in addition, the mixed enzyme is not easy to flowback; the invention selects magnesium peroxide as the oxidant of the oxidation type gel breaker, the magnesium peroxide is released after the biological enzyme gel breaker is consumed, the system of the drilling and completion fluid in the well is weak acid at the moment, the magnesium peroxide is soaked in the weak acid to form hydrogen peroxide, polymers which are not degraded by biological enzyme and acid-resistant polymers can be further decomposed, and the thoroughness of removing filter cakes is ensured.

Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention.

Detailed Description

The present invention is further described in detail below with reference to examples so that those skilled in the art can practice the invention with reference to the description.

It will be understood that terms such as "having," "including," and "comprising," as used herein, do not preclude the presence or addition of one or more other elements or groups thereof.

It is to be noted that the experimental methods described in the following embodiments are all conventional methods unless otherwise specified, and the reagents and materials are commercially available unless otherwise specified.

< example 1>

The invention provides a strong-inhibition bunching environment-friendly drilling and completion fluid which comprises 80 parts by weight of base fluid, 10 parts by weight of microemulsion nano preparation, 1 part by weight of plugging anti-collapse agent, 1 part by weight of oil-soluble temporary plugging agent and 0.8 part by weight of corrosion inhibitor; the micro-emulsion nano preparation comprises an oxidation type gel breaker, a biological enzyme gel breaker, an acid gel breaker and a capsule shell from inside to outside in sequence; the oxidation type gel breaker, the biological enzyme gel breaker and the acid gel breaker are isolated by coating films;

the oxidation type gel breaker comprises 3 parts by weight of potassium permanganate solution, 0.5 part by weight of magnesium peroxide, 0.1 part by weight of vegetable oil and 0.03 part by weight of xanthan gum;

the biological enzyme gel breaker comprises 3 parts by weight of l,4- β -D-mannase solution, 0.3 part by weight of glycerol and 0.03 part by weight of gelatin;

the acid gel breaker comprises β -cyclodextrin of 1 weight part, citric acid of 5 weight parts, ethylenediamine tetraacetic acid of 3 weight parts and sodium hypophosphite of 1 weight part;

the capsule shell comprises 3 parts by weight of xanthan gum, 0.5 part by weight of acrylic resin L100-55 and 0.3 part by weight of glycerol;

the base liquid comprises water, a polyene polyamine organic acid salt and base oil in a weight ratio of 10:0.4: 2.

The preparation method of the microemulsion nano preparation comprises the following steps:

step S1, weighing 3 parts by weight of potassium permanganate solution, 0.5 part by weight of magnesium peroxide, 0.1 part by weight of vegetable oil and 0.03 part by weight of xanthan gum, and uniformly mixing to obtain the emulsified oxidation type gel breaker; preparing a sodium alginate solution with the mass fraction of 3% by using water and sodium alginate, heating to enable the sodium alginate solution to be in a sol state to obtain a sodium alginate colloid, adding an oxidation type gel breaker into the sodium alginate colloid to enable the oxidation type gel breaker to be suspended in the sodium alginate colloid to obtain a suspension, then dropwise adding the suspension into a calcium chloride solution with the mass fraction of 2% by using a dropper, slowly stirring clockwise for 10min, and then pouring out the calcium chloride solution to obtain a core material;

step S2, weighing 3 parts by weight of l,4- β -D-mannase solution, 0.3 part by weight of glycerol and 0.03 part by weight of gelatin, uniformly stirring to obtain the biological enzyme gel breaker, weighing 1 part by weight of β -cyclodextrin, 5 parts by weight of citric acid, 3 parts by weight of ethylenediamine tetraacetic acid and 1 part by weight of sodium hypophosphite, dissolving in 10 parts by weight of water, uniformly stirring, heating to 80 ℃, and continuously stirring for 1h to obtain the acid gel breaker;

step S3, weighing 2 parts by weight of gelatin, 0.2 part by weight of polyethylene glycol, 1 part by weight of white oil and 5 parts by weight of water, and fully and uniformly stirring to obtain a coating liquid; weighing 3 parts by weight of xanthan gum, 0.5 part by weight of acrylic resin L100-55, 0.3 part by weight of glycerol and 20 parts by weight of water, and uniformly mixing to obtain a capsule shell;

step S4, equally dividing the coating film liquid into two equal parts, putting the nuclear material obtained in the step S1 into a fluidized bed coating machine, and controlling the air pressure in the fluidized bed coating machine to be 0.2MPa and the internal temperature to be 25 ℃ so that the nuclear material forms an annular fluidized state; sequentially filling a first coating film liquid, a biological enzyme gel breaker, a second coating film liquid, an acid gel breaker and a capsule shell into a liquid reservoir of a fluidized bed coating machine, sequentially spraying the first coating film liquid, the biological enzyme gel breaker, the second coating film liquid, the acid gel breaker and the capsule shell on a core material through a peristaltic pump to form a multi-layer coating, keeping an annular fluidization state for 5min after spraying of the capsule shell is completed each time, closing an air compressor after spraying of the capsule shell is completed, taking out the multi-layer coating, and air-drying to obtain the microemulsion nano preparation.

< example 2>

The invention provides a strong-inhibition bunching environment-friendly drilling and completion fluid which comprises 90 parts by weight of base fluid, 20 parts by weight of microemulsion nano preparation, 3 parts by weight of plugging anti-collapse agent, 3 parts by weight of oil-soluble temporary plugging agent and 1.2 parts by weight of corrosion inhibitor; the micro-emulsion nano preparation comprises an oxidation type gel breaker, a biological enzyme gel breaker, an acid gel breaker and a capsule shell from inside to outside in sequence; the oxidation type gel breaker, the biological enzyme gel breaker and the acid gel breaker are isolated by coating films;

the oxidation type gel breaker comprises 7 parts by weight of potassium permanganate solution, 2 parts by weight of magnesium peroxide, 0.3 part by weight of vegetable oil and 0.08 part by weight of xanthan gum;

the biological enzyme gel breaker comprises 8 parts by weight of l,4- β -D-mannase solution, 0.6 part by weight of glycerol and 0.08 part by weight of gelatin;

the acid gel breaker comprises β -cyclodextrin of 8 weight parts, citric acid of 10 weight parts, ethylene diamine tetraacetic acid of 8 weight parts and sodium hypophosphite of 6 weight parts;

the capsule shell comprises 8 parts by weight of xanthan gum, 0.9 part by weight of acrylic resin L100-55 and 0.6 part by weight of glycerol;

the base liquid comprises water, a polyene polyamine organic acid salt and base oil in a weight ratio of 10:0.4: 2.

The preparation method of the microemulsion nano preparation comprises the following steps:

s1, weighing 7 parts by weight of potassium permanganate solution, 2 parts by weight of magnesium peroxide, 0.3 part by weight of vegetable oil and 0.08 part by weight of xanthan gum, and uniformly mixing to obtain the emulsified oxidation type gel breaker; preparing a sodium alginate solution with the mass fraction of 4% by using water and sodium alginate, heating to enable the sodium alginate solution to be in a sol state to obtain a sodium alginate colloid, adding an oxidation type gel breaker into the sodium alginate colloid to enable the oxidation type gel breaker to be suspended in the sodium alginate colloid to obtain a suspension, then dropwise adding the suspension into a calcium chloride solution with the mass fraction of 2% by using a dropper, clockwise slowly stirring for 15min, and then pouring out the calcium chloride solution to obtain a core material;

s2, weighing 8 parts by weight of l,4- β -D-mannase solution, 0.6 part by weight of glycerol and 0.08 part by weight of gelatin, uniformly stirring to obtain the biological enzyme gel breaker, weighing 8 parts by weight of β -cyclodextrin, 10 parts by weight of citric acid, 8 parts by weight of ethylenediamine tetraacetic acid and 6 parts by weight of sodium hypophosphite, dissolving in 20 parts by weight of water, uniformly stirring, heating to 90 ℃, and continuously stirring for 2 hours to obtain the acid gel breaker;

step S3, weighing 6 parts by weight of gelatin, 0.6 part by weight of polyethylene glycol, 3 parts by weight of white oil and 10 parts by weight of water, and fully and uniformly stirring to obtain a coating liquid; weighing 8 parts by weight of xanthan gum, 0.9 part by weight of acrylic resin L100-55, 0.6 part by weight of glycerol and 25 parts by weight of water, and uniformly mixing to obtain a capsule shell;

step S4, equally dividing the coating film liquid into two equal parts, putting the nuclear material obtained in the step S1 into a fluidized bed coating machine, and controlling the air pressure in the fluidized bed coating machine to be 0.4MPa and the internal temperature to be 35 ℃ so that the nuclear material forms an annular fluidized state; sequentially filling a first coating film liquid, a biological enzyme gel breaker, a second coating film liquid, an acid gel breaker and a capsule shell into a liquid reservoir of a fluidized bed coating machine, sequentially spraying the first coating film liquid, the biological enzyme gel breaker, the second coating film liquid, the acid gel breaker and the capsule shell on a core material through a peristaltic pump to obtain a multi-layer coating, keeping an annular fluidization state for 8min after spraying is completed each time, closing an air compressor after spraying of the capsule shell is completed, taking out the multi-layer coating, and air-drying to obtain the microemulsion nano preparation.

< example 3>

The invention provides a strong-inhibition bunching environment-friendly drilling and completion fluid which comprises 85 parts by weight of base fluid, 15 parts by weight of microemulsion nano preparation, 2 parts by weight of plugging anti-collapse agent, 2 parts by weight of oil-soluble temporary plugging agent and 1.0 part by weight of corrosion inhibitor; the micro-emulsion nano preparation comprises an oxidation type gel breaker, a biological enzyme gel breaker, an acid gel breaker and a capsule shell from inside to outside in sequence; the oxidation type gel breaker, the biological enzyme gel breaker and the acid gel breaker are isolated by coating films;

the oxidation type gel breaker comprises 5 parts by weight of potassium permanganate solution, 1.3 parts by weight of magnesium peroxide, 0.2 part by weight of vegetable oil and 0.06 part by weight of xanthan gum;

the biological enzyme gel breaker comprises 6 parts by weight of l,4- β -D-mannase solution, 0.5 part by weight of glycerol and 0.05 part by weight of gelatin;

the acid gel breaker comprises β -cyclodextrin of 5 parts by weight, citric acid of 8 parts by weight, ethylenediamine tetraacetic acid of 5 parts by weight and sodium hypophosphite of 3 parts by weight;

the capsule shell comprises 6 parts by weight of xanthan gum, 0.7 part by weight of acrylic resin L100-55 and 0.5 part by weight of glycerol;

the base fluid comprises water, a polyene polyamine organic acid salt and base oil in a weight ratio of 10:0.4: 2;

the preparation method of the microemulsion nano preparation comprises the following steps:

step S1, weighing 5 parts by weight of potassium permanganate solution, and uniformly mixing 1.3 parts by weight of magnesium peroxide, 0.2 part by weight of vegetable oil and 0.06 part by weight of xanthan gum to obtain the emulsified oxidized gel breaker; preparing a sodium alginate solution with the mass fraction of 3.5% by using water and sodium alginate, heating to enable the sodium alginate solution to be in a sol state to obtain a sodium alginate colloid, adding an oxidation type gel breaker into the sodium alginate colloid to enable the oxidation type gel breaker to be suspended in the sodium alginate colloid to obtain a suspension, then dropwise adding the suspension into a calcium chloride solution with the mass fraction of 2% by using a dropper, slowly stirring for 13min clockwise, and pouring out the calcium chloride solution to obtain a core material;

s2, weighing 6 parts by weight of l,4- β -D-mannase solution, 0.5 part by weight of glycerol and 0.05 part by weight of gelatin, uniformly stirring to obtain a biological enzyme gel breaker, weighing 5 parts by weight of β -cyclodextrin, 8 parts by weight of citric acid, 5 parts by weight of ethylenediamine tetraacetic acid and 3 parts by weight of sodium hypophosphite, dissolving in 15 parts of water, uniformly stirring, heating to 85 ℃, and continuously stirring for 1.5 hours to obtain an acid gel breaker;

step S3, weighing 4 parts by weight of gelatin, 0.4 part by weight of polyethylene glycol, 2 parts by weight of white oil and 8 parts by weight of water, and fully and uniformly stirring to obtain a coating liquid; weighing 6 parts by weight of xanthan gum, 0.7 part by weight of acrylic resin L100-55, 0.5 part by weight of glycerol and 23 parts by weight of water, and uniformly mixing to obtain a capsule shell;

step S4, equally dividing the coating film liquid into two equal parts, putting the nuclear material obtained in the step S1 into a fluidized bed coating machine, and controlling the air pressure in the fluidized bed coating machine to be 0.3MPa and the internal temperature to be 30 ℃ so that the nuclear material forms an annular fluidized state; sequentially filling a first coating film liquid, a biological enzyme gel breaker, a second coating film liquid, an acid gel breaker and a capsule shell into a liquid reservoir of a fluidized bed coating machine, sequentially spraying the first coating film liquid, the biological enzyme gel breaker, the second coating film liquid, the acid gel breaker and the capsule shell on a core material through a peristaltic pump to obtain a multi-layer coating, keeping an annular fluidization state for 7min after spraying is completed each time, keeping the annular fluidization state for 70min after spraying of the capsule shell is completed, closing an air compressor, taking out the multi-layer coating, and air-drying to obtain the microemulsion nano preparation.

< comparative example 1>

The environment-friendly drilling and completion fluid capable of strongly inhibiting bunching comprises 85 parts by weight of base fluid, 15 parts by weight of micro-emulsion nano preparation, 2 parts by weight of plugging anti-collapse agent, 2 parts by weight of oil-soluble temporary plugging agent and 1.0 part by weight of corrosion inhibitor; the micro-emulsion nano preparation comprises an oxidation type gel breaker and a capsule shell from inside to outside in sequence; the base fluid comprises water, a polyene polyamine organic acid salt and base oil in a weight ratio of 10:0.4: 2;

the oxidation type gel breaker comprises 5 parts by weight of potassium permanganate solution, 1.3 parts by weight of magnesium peroxide, 0.2 part by weight of vegetable oil and 0.06 part by weight of xanthan gum;

the capsule shell comprises 6 parts by weight of xanthan gum, 0.7 part by weight of acrylic resin L100-55 and 0.5 part by weight of glycerol;

the preparation method of the microemulsion nano preparation comprises the following steps:

step S1, weighing 5 parts by weight of potassium permanganate solution, and uniformly mixing 1.3 parts by weight of magnesium peroxide, 0.2 part by weight of vegetable oil and 0.06 part by weight of xanthan gum to obtain the emulsified oxidized gel breaker; preparing a sodium alginate solution with the mass fraction of 3.5% by using water and sodium alginate, heating to enable the sodium alginate solution to be in a sol state to obtain a sodium alginate colloid, adding an oxidation type gel breaker into the sodium alginate colloid to enable the oxidation type gel breaker to be suspended in the sodium alginate colloid to obtain a suspension, then dropwise adding the suspension into a calcium chloride solution with the mass fraction of 2% by using a dropper, slowly stirring for 13min clockwise, and pouring out the calcium chloride solution to obtain a core material;

step S2, weighing 6 parts by weight of xanthan gum, 0.7 part by weight of acrylic resin L100-55, 0.5 part by weight of glycerol and 23 parts by weight of water, and uniformly mixing to obtain a capsule shell;

s3, putting the nuclear material obtained in the step S1 into a fluidized bed coating machine, and controlling the air pressure in the fluidized bed coating machine to be 0.3MPa and the internal temperature to be 30 ℃ so that the nuclear material forms an annular fluidized state; filling a capsule shell into a liquid storage device of a fluidized bed coating machine, spraying the capsule shell on a core material through a peristaltic pump to obtain a multilayer coating, keeping an annular fluidization state for 70min after spraying, turning off an air compressor, taking out the multilayer coating, and air-drying to obtain the microemulsion nano preparation.

< comparative example 2>

The environment-friendly drilling and completion fluid capable of strongly inhibiting bunching comprises 85 parts by weight of base fluid, 15 parts by weight of micro-emulsion nano preparation, 2 parts by weight of plugging anti-collapse agent, 2 parts by weight of oil-soluble temporary plugging agent and 1.0 part by weight of corrosion inhibitor; the micro-emulsion nano preparation is a biological enzyme gel breaker and a capsule shell in sequence from inside to outside; the base fluid comprises water, a polyene polyamine organic acid salt and base oil in a weight ratio of 10:0.4: 2;

the biological enzyme gel breaker comprises 6 parts by weight of l,4- β -D-mannase solution, 0.5 part by weight of glycerol and 0.05 part by weight of gelatin;

the capsule shell comprises 6 parts by weight of xanthan gum, 0.7 part by weight of acrylic resin L100-55 and 0.5 part by weight of glycerol;

step S1, weighing 6 parts by weight of l,4- β -D-mannase solution, 0.5 part by weight of glycerol and 0.05 part by weight of gelatin, uniformly stirring to obtain a biological enzyme gel breaker, preparing a sodium alginate solution with the mass fraction of 3.5% by using water and sodium alginate, heating to enable the sodium alginate solution to be in a sol state to obtain a sodium alginate colloid, adding the biological enzyme gel breaker into the sodium alginate colloid to obtain a mixed solution, then dropwise adding the mixed solution into a calcium chloride solution with the mass fraction of 2% by using a dropper, slowly stirring for 13min clockwise, pouring the calcium chloride solution out to obtain a core material;

step S2, weighing 6 parts by weight of xanthan gum, 0.7 part by weight of acrylic resin L100-55, 0.5 part by weight of glycerol and 23 parts by weight of water, and uniformly mixing to obtain a capsule shell;

s3, putting the nuclear material obtained in the step S1 into a fluidized bed coating machine, and controlling the air pressure in the fluidized bed coating machine to be 0.3MPa and the internal temperature to be 30 ℃ so that the nuclear material forms an annular fluidized state; filling a capsule shell into a liquid storage device of a fluidized bed coating machine, spraying the capsule shell on a core material through a peristaltic pump to obtain a multilayer coating, keeping an annular fluidization state for 70min after spraying, turning off an air compressor, taking out the multilayer coating, and air-drying to obtain the microemulsion nano preparation.

< comparative example 3>

The environment-friendly drilling and completion fluid capable of strongly inhibiting bunching comprises 85 parts by weight of base fluid, 15 parts by weight of micro-emulsion nano preparation, 2 parts by weight of plugging anti-collapse agent, 2 parts by weight of oil-soluble temporary plugging agent and 1.0 part by weight of corrosion inhibitor; the micro-emulsion nano preparation comprises an acidic gel breaker and a capsule shell from inside to outside in sequence; the base fluid comprises water, a polyene polyamine organic acid salt and base oil in a weight ratio of 10:0.4: 2;

the acid gel breaker comprises β -cyclodextrin of 5 parts by weight, citric acid of 8 parts by weight, ethylenediamine tetraacetic acid of 5 parts by weight and sodium hypophosphite of 3 parts by weight;

the capsule shell comprises 6 parts by weight of xanthan gum, 0.7 part by weight of acrylic resin L100-55 and 0.5 part by weight of glycerol;

s1, weighing 5 parts by weight of β -cyclodextrin, 8 parts by weight of citric acid, 5 parts by weight of ethylenediamine tetraacetic acid and 3 parts by weight of sodium hypophosphite, dissolving the mixture in 15 parts of water, uniformly stirring, heating to 85 ℃, continuously stirring for 1.5 hours to obtain an acid gel breaker, preparing a sodium alginate solution with the mass fraction of 3.5% by using water and sodium alginate, heating the sodium alginate solution to form a sol state to obtain a sodium alginate colloid, adding the acid gel breaker into the sodium alginate colloid to suspend the acid gel breaker in the sodium alginate colloid to obtain a suspension, then dropwise adding the suspension into a calcium chloride solution with the mass fraction of 2% by using a dropper, slowly stirring clockwise for 13 minutes, and pouring out the calcium chloride solution to obtain a core material;

step S2, weighing 6 parts by weight of xanthan gum, 0.7 part by weight of acrylic resin L100-55, 0.5 part by weight of glycerol and 23 parts by weight of water, and uniformly mixing to obtain a capsule shell;

s3, putting the nuclear material obtained in the step S1 into a fluidized bed coating machine, and controlling the air pressure in the fluidized bed coating machine to be 0.3MPa and the internal temperature to be 30 ℃ so that the nuclear material forms an annular fluidized state; filling a capsule shell into a liquid storage device of a fluidized bed coating machine, spraying the capsule shell on a core material through a peristaltic pump to obtain a multilayer coating, keeping an annular fluidization state for 70min after spraying, turning off an air compressor, taking out the multilayer coating, and air-drying to obtain the microemulsion nano preparation.

< comparative example 4>

The invention provides a strong-inhibition bunching environment-friendly drilling and completion fluid which comprises 85 parts by weight of base fluid, 15 parts by weight of microemulsion nano preparation, 2 parts by weight of plugging anti-collapse agent, 2 parts by weight of oil-soluble temporary plugging agent and 1.0 part by weight of corrosion inhibitor; the micro-emulsion nano preparation comprises an oxidation type gel breaker, a biological enzyme gel breaker and a capsule shell from inside to outside in sequence; the oxidation type gel breaker and the biological enzyme gel breaker are isolated by a coating film;

the oxidation type gel breaker comprises 5 parts by weight of potassium permanganate solution, 1.3 parts by weight of magnesium peroxide, 0.2 part by weight of vegetable oil and 0.06 part by weight of xanthan gum;

the biological enzyme gel breaker comprises 6 parts by weight of l,4- β -D-mannase solution, 0.5 part by weight of glycerol and 0.05 part by weight of gelatin;

the capsule shell comprises 6 parts by weight of xanthan gum, 0.7 part by weight of acrylic resin L100-55 and 0.5 part by weight of glycerol;

the base fluid comprises water, a polyene polyamine organic acid salt and base oil in a weight ratio of 10:0.4: 2;

the preparation method of the microemulsion nano preparation comprises the following steps:

step S1, weighing 5 parts by weight of potassium permanganate solution, and uniformly mixing 1.3 parts by weight of magnesium peroxide, 0.2 part by weight of vegetable oil and 0.06 part by weight of xanthan gum to obtain the emulsified oxidized gel breaker; preparing a sodium alginate solution with the mass fraction of 3.5% by using water and sodium alginate, heating to enable the sodium alginate solution to be in a sol state to obtain a sodium alginate colloid, adding an oxidation type gel breaker into the sodium alginate colloid to enable the oxidation type gel breaker to be suspended in the sodium alginate colloid to obtain a suspension, then dropwise adding the suspension into a calcium chloride solution with the mass fraction of 2% by using a dropper, slowly stirring for 13min clockwise, and pouring out the calcium chloride solution to obtain a core material;

s2, weighing 6 parts by weight of l,4- β -D-mannase solution, 0.5 part by weight of glycerol and 0.05 part by weight of gelatin, and uniformly stirring to obtain the biological enzyme gel breaker;

step S3, weighing 4 parts by weight of gelatin, 0.4 part by weight of polyethylene glycol, 2 parts by weight of white oil and 8 parts by weight of water, and fully and uniformly stirring to obtain a coating liquid; weighing 6 parts by weight of xanthan gum, 0.7 part by weight of acrylic resin L100-55, 0.5 part by weight of glycerol and 23 parts by weight of water, and uniformly mixing to obtain a capsule shell;

s4, putting the nuclear material obtained in the step S1 into a fluidized bed coating machine, and controlling the air pressure in the fluidized bed coating machine to be 0.3MPa and the internal temperature to be 30 ℃ so that the nuclear material forms an annular fluidized state; and sequentially filling a coating film liquid, a biological enzyme gel breaker and a capsule shell into a liquid reservoir of a fluidized bed coating machine, sequentially spraying the coating film, the biological enzyme gel breaker and the capsule shell on the core material through a peristaltic pump to obtain a multi-layer coating, keeping the annular fluidization state for 7min after spraying of the capsule shell is completed each time, keeping the annular fluidization state for 70min after spraying of the capsule shell is completed, closing an air compressor, taking out the multi-layer coating, and air-drying to obtain the microemulsion nano preparation.

< comparative example 5>

The invention provides a strong-inhibition bunching environment-friendly drilling and completion fluid which comprises 85 parts by weight of base fluid, 15 parts by weight of microemulsion nano preparation, 2 parts by weight of plugging anti-collapse agent, 2 parts by weight of oil-soluble temporary plugging agent and 1.0 part by weight of corrosion inhibitor; the micro-emulsion nano preparation comprises an oxidation type gel breaker, an acid gel breaker and a capsule shell from inside to outside in sequence; the oxidation type gel breaker and the acid gel breaker are isolated by a coating film;

the oxidation type gel breaker comprises 5 parts by weight of potassium permanganate solution, 1.3 parts by weight of magnesium peroxide, 0.2 part by weight of vegetable oil and 0.06 part by weight of xanthan gum;

the acid gel breaker comprises β -cyclodextrin of 5 parts by weight, citric acid of 8 parts by weight, ethylenediamine tetraacetic acid of 5 parts by weight and sodium hypophosphite of 3 parts by weight;

the capsule shell comprises 6 parts by weight of xanthan gum, 0.7 part by weight of acrylic resin L100-55 and 0.5 part by weight of glycerol;

the base fluid comprises water, a polyene polyamine organic acid salt and base oil in a weight ratio of 10:0.4: 2;

the preparation method of the microemulsion nano preparation comprises the following steps:

step S1, weighing 5 parts by weight of potassium permanganate solution, and uniformly mixing 1.3 parts by weight of magnesium peroxide, 0.2 part by weight of vegetable oil and 0.06 part by weight of xanthan gum to obtain the emulsified oxidized gel breaker; preparing a sodium alginate solution with the mass fraction of 3.5% by using water and sodium alginate, heating to enable the sodium alginate solution to be in a sol state to obtain a sodium alginate colloid, adding an oxidation type gel breaker into the sodium alginate colloid to enable the oxidation type gel breaker to be suspended in the sodium alginate colloid to obtain a suspension, then dropwise adding the suspension into a calcium chloride solution with the mass fraction of 2% by using a dropper, slowly stirring for 13min clockwise, and pouring out the calcium chloride solution to obtain a core material;

s2, weighing 5 parts by weight of β -cyclodextrin, 8 parts by weight of citric acid, 5 parts by weight of ethylenediamine tetraacetic acid and 3 parts by weight of sodium hypophosphite, dissolving in 15 parts of water, uniformly stirring, heating to 85 ℃, and continuously stirring for 1.5 hours to obtain the acid gel breaker;

step S3, weighing 4 parts by weight of gelatin, 0.4 part by weight of polyethylene glycol, 2 parts by weight of white oil and 8 parts by weight of water, and fully and uniformly stirring to obtain a coating liquid; weighing 6 parts by weight of xanthan gum, 0.7 part by weight of acrylic resin L100-55, 0.5 part by weight of glycerol and 23 parts by weight of water, and uniformly mixing to obtain a capsule shell;

step S4, equally dividing the coating film liquid into two equal parts, putting the nuclear material obtained in the step S1 into a fluidized bed coating machine, and controlling the air pressure in the fluidized bed coating machine to be 0.3MPa and the internal temperature to be 30 ℃ so that the nuclear material forms an annular fluidized state; and (2) sequentially filling a coating film liquid, an acidic gel breaker and a capsule shell into a liquid reservoir of the fluidized bed coating machine, sequentially spraying the coating film liquid, the acidic gel breaker and the capsule shell on the core material through a peristaltic pump to obtain a multi-layer coating, keeping the annular fluidization state for 7min after spraying of the capsule shell is completed each time, keeping the annular fluidization state for 70min after spraying of the capsule shell is completed, closing an air compressor, taking out the multi-layer coating, and air-drying to obtain the micro-emulsion nano preparation.

< comparative example 6>

The invention provides a strong-inhibition bunching environment-friendly drilling and completion fluid which comprises 85 parts by weight of base fluid, 15 parts by weight of microemulsion nano preparation, 2 parts by weight of plugging anti-collapse agent, 2 parts by weight of oil-soluble temporary plugging agent and 1.0 part by weight of corrosion inhibitor; the micro-emulsion nano preparation comprises a biological enzyme gel breaker, an acid gel breaker and a capsule shell from inside to outside in sequence; the biological enzyme gel breaker and the acid gel breaker are isolated by a coating film;

the biological enzyme gel breaker comprises 6 parts by weight of l,4- β -D-mannase solution, 0.5 part by weight of glycerol and 0.05 part by weight of gelatin;

the acid gel breaker comprises β -cyclodextrin of 5 parts by weight, citric acid of 8 parts by weight, ethylenediamine tetraacetic acid of 5 parts by weight and sodium hypophosphite of 3 parts by weight;

the capsule shell comprises 6 parts by weight of xanthan gum, 0.7 part by weight of acrylic resin L100-55 and 0.5 part by weight of glycerol;

the base fluid comprises water, a polyene polyamine organic acid salt and base oil in a weight ratio of 10:0.4: 2;

the preparation method of the microemulsion nano preparation comprises the following steps:

step S1, weighing 6 parts by weight of l,4- β -D-mannase solution, 0.5 part by weight of glycerol and 0.05 part by weight of gelatin, uniformly stirring to obtain a biological enzyme gel breaker, preparing a sodium alginate solution with the mass fraction of 3.5% by using water and sodium alginate, heating to enable the sodium alginate solution to be in a sol state to obtain a sodium alginate colloid, adding the biological enzyme gel breaker into the sodium alginate colloid to obtain a mixed solution, then dropwise adding the mixed solution into a calcium chloride solution with the mass fraction of 2% by using a dropper, slowly stirring for 13min clockwise, pouring the calcium chloride solution out to obtain a core material;

s2, weighing 5 parts by weight of β -cyclodextrin, 8 parts by weight of citric acid, 5 parts by weight of ethylenediamine tetraacetic acid and 3 parts by weight of sodium hypophosphite, dissolving in 15 parts of water, uniformly stirring, heating to 85 ℃, and continuously stirring for 1.5 hours to obtain the acid gel breaker;

step S3, weighing 4 parts by weight of gelatin, 0.4 part by weight of polyethylene glycol, 2 parts by weight of white oil and 8 parts by weight of water, and fully and uniformly stirring to obtain a coating liquid; weighing 6 parts by weight of xanthan gum, 0.7 part by weight of acrylic resin L100-55, 0.5 part by weight of glycerol and 23 parts by weight of water, and uniformly mixing to obtain a capsule shell;

step S4, equally dividing the coating film liquid into two equal parts, putting the nuclear material obtained in the step S1 into a fluidized bed coating machine, and controlling the air pressure in the fluidized bed coating machine to be 0.3MPa and the internal temperature to be 30 ℃ so that the nuclear material forms an annular fluidized state; and (2) sequentially filling a coating film liquid, an acidic gel breaker and a capsule shell into a liquid reservoir of the fluidized bed coating machine, sequentially spraying the coating film liquid, the acidic gel breaker and the capsule shell on the core material through a peristaltic pump to obtain a multi-layer coating, keeping the annular fluidization state for 7min after spraying of the capsule shell is completed each time, keeping the annular fluidization state for 70min after spraying of the capsule shell is completed, closing an air compressor, taking out the multi-layer coating, and air-drying to obtain the micro-emulsion nano preparation.

< comparative example 7>

The invention provides a strong-inhibition bunching environment-friendly drilling and completion fluid which comprises 85 parts by weight of base fluid, 15 parts by weight of microemulsion nano preparation, 2 parts by weight of plugging anti-collapse agent, 2 parts by weight of oil-soluble temporary plugging agent and 1.0 part by weight of corrosion inhibitor; the micro-emulsion nano preparation comprises a biological enzyme gel breaker, an oxidation type gel breaker, an acid gel breaker and a capsule shell from inside to outside in sequence; the biological enzyme gel breaker and the oxidation type gel breaker, and the oxidation type gel breaker and the acid gel breaker are isolated by coating films;

the biological enzyme gel breaker comprises 6 parts by weight of l,4- β -D-mannase solution, 0.5 part by weight of glycerol and 0.05 part by weight of gelatin;

the oxidation type gel breaker comprises 5 parts by weight of potassium permanganate solution, 1.3 parts by weight of magnesium peroxide, 0.2 part by weight of vegetable oil and 0.06 part by weight of xanthan gum;

the acid gel breaker comprises β -cyclodextrin of 5 parts by weight, citric acid of 8 parts by weight, ethylenediamine tetraacetic acid of 5 parts by weight and sodium hypophosphite of 3 parts by weight;

the capsule shell comprises 6 parts by weight of xanthan gum, 0.7 part by weight of acrylic resin L100-55 and 0.5 part by weight of glycerol;

the base fluid comprises water, a polyene polyamine organic acid salt and base oil in a weight ratio of 10:0.4: 2;

the preparation method of the microemulsion nano preparation comprises the following steps:

step S1, weighing 6 parts by weight of l,4- β -D-mannase solution, 0.5 part by weight of glycerol and 0.05 part by weight of gelatin, uniformly stirring to obtain a biological enzyme gel breaker, preparing a sodium alginate solution with the mass fraction of 3.5% by using water and sodium alginate, heating to enable the sodium alginate solution to be in a sol state to obtain a sodium alginate colloid, adding the biological enzyme gel breaker into the sodium alginate colloid to obtain a mixed solution, then dropwise adding the mixed solution into a calcium chloride solution with the mass fraction of 2% by using a dropper, slowly stirring for 13min clockwise, pouring the calcium chloride solution out to obtain a core material;

s2, weighing 5 parts by weight of potassium permanganate solution, uniformly mixing 1.3 parts by weight of magnesium peroxide, 0.2 part by weight of vegetable oil and 0.06 part by weight of xanthan gum to obtain an emulsified oxidation type gel breaker, weighing 5 parts by weight of β -cyclodextrin, 8 parts by weight of citric acid, 5 parts by weight of ethylenediamine tetraacetic acid and 3 parts by weight of sodium hypophosphite, dissolving in 15 parts by weight of water, uniformly stirring, heating to 85 ℃, and continuously stirring for 1.5 hours to obtain an acid gel breaker;

step S3, weighing 4 parts by weight of gelatin, 0.4 part by weight of polyethylene glycol, 2 parts by weight of white oil and 8 parts by weight of water, and fully and uniformly stirring to obtain a coating liquid; weighing 6 parts by weight of xanthan gum, 0.7 part by weight of acrylic resin L100-55, 0.5 part by weight of glycerol and 23 parts by weight of water, and uniformly mixing to obtain a capsule shell;

step S4, equally dividing the coating film liquid into two equal parts, putting the nuclear material obtained in the step S1 into a fluidized bed coating machine, and controlling the air pressure in the fluidized bed coating machine to be 0.3MPa and the internal temperature to be 30 ℃ so that the nuclear material forms an annular fluidized state; sequentially filling a first coating film liquid, an oxidation type gel breaker, a second coating film liquid, an acid gel breaker and a capsule shell into a liquid storage device of a fluidized bed coating machine, sequentially spraying the first coating film liquid, the oxidation type gel breaker, the second coating film liquid, the acid gel breaker and the capsule shell on a core material through a peristaltic pump to obtain a multi-layer coating, keeping an annular fluidization state for 7min after spraying is completed each time, keeping the annular fluidization state for 70min after spraying of the capsule shell is completed, closing an air compressor, taking out the multi-layer coating, and air-drying to obtain the micro-emulsion nano preparation.

< comparative example 8>

The invention provides a strong-inhibition bunching environment-friendly drilling and completion fluid which comprises 85 parts by weight of base fluid, 15 parts by weight of microemulsion nano preparation, 2 parts by weight of plugging anti-collapse agent, 2 parts by weight of oil-soluble temporary plugging agent and 1.0 part by weight of corrosion inhibitor; the micro-emulsion nano preparation comprises a biological enzyme gel breaker, an acidic gel breaker, an oxidation type gel breaker and a capsule shell from inside to outside in sequence; the biological enzyme gel breaker, the acidic gel breaker and the oxidation type gel breaker are isolated by coating films;

the biological enzyme gel breaker comprises 6 parts by weight of l,4- β -D-mannase solution, 0.5 part by weight of glycerol and 0.05 part by weight of gelatin;

the acid gel breaker comprises β -cyclodextrin of 5 parts by weight, citric acid of 8 parts by weight, ethylenediamine tetraacetic acid of 5 parts by weight and sodium hypophosphite of 3 parts by weight;

the oxidation type gel breaker comprises 5 parts by weight of potassium permanganate solution, 1.3 parts by weight of magnesium peroxide, 0.2 part by weight of vegetable oil and 0.06 part by weight of xanthan gum;

the capsule shell comprises 6 parts by weight of xanthan gum, 0.7 part by weight of acrylic resin L100-55 and 0.5 part by weight of glycerol;

the base fluid comprises water, a polyene polyamine organic acid salt and base oil in a weight ratio of 10:0.4: 2;

the preparation method of the microemulsion nano preparation comprises the following steps:

step S1, weighing 6 parts by weight of l,4- β -D-mannase solution, 0.5 part by weight of glycerol and 0.05 part by weight of gelatin, uniformly stirring to obtain a biological enzyme gel breaker, preparing a sodium alginate solution with the mass fraction of 3.5% by using water and sodium alginate, heating to enable the sodium alginate solution to be in a sol state to obtain a sodium alginate colloid, adding the biological enzyme gel breaker into the sodium alginate colloid to obtain a mixed solution, then dropwise adding the mixed solution into a calcium chloride solution with the mass fraction of 2% by using a dropper, slowly stirring for 13min clockwise, pouring the calcium chloride solution out to obtain a core material;

s2, weighing 5 parts by weight of β -cyclodextrin, 8 parts by weight of citric acid, 5 parts by weight of ethylenediamine tetraacetic acid and 3 parts by weight of sodium hypophosphite, dissolving in 15 parts of water, uniformly stirring, heating to 85 ℃, and continuously stirring for 1.5 hours to obtain an acid gel breaker;

step S3, weighing 4 parts by weight of gelatin, 0.4 part by weight of polyethylene glycol, 2 parts by weight of white oil and 8 parts by weight of water, and fully and uniformly stirring to obtain a coating liquid; weighing 6 parts by weight of xanthan gum, 0.7 part by weight of acrylic resin L100-55, 0.5 part by weight of glycerol and 23 parts by weight of water, and uniformly mixing to obtain a capsule shell;

step S4, equally dividing the coating film liquid into two equal parts, putting the nuclear material obtained in the step S1 into a fluidized bed coating machine, and controlling the air pressure in the fluidized bed coating machine to be 0.3MPa and the internal temperature to be 30 ℃ so that the nuclear material forms an annular fluidized state; sequentially filling a first coating film liquid, an acidic gel breaker, a second coating film liquid, an oxidation type gel breaker and a capsule shell into a liquid reservoir of a fluidized bed coating machine, sequentially spraying the first coating film liquid, the acidic gel breaker, the second coating film liquid, the oxidation type gel breaker and the capsule shell on a core material through a peristaltic pump to obtain a multi-layer coating, keeping an annular fluidization state for 7min after spraying is completed each time, keeping the annular fluidization state for 70min after spraying of the capsule shell is completed, closing an air compressor, taking out the multi-layer coating, and air-drying to obtain the microemulsion nano preparation.

< comparative example 9>

The invention provides a strong-inhibition bunching environment-friendly drilling and completion fluid which comprises 85 parts by weight of base fluid, 15 parts by weight of microemulsion nano preparation, 2 parts by weight of plugging anti-collapse agent, 2 parts by weight of oil-soluble temporary plugging agent and 1.0 part by weight of corrosion inhibitor; the micro-emulsion nano preparation comprises an acidic gel breaker, an oxidation type gel breaker, a biological enzyme gel breaker and a capsule shell from inside to outside in sequence; the acid gel breaker, the oxidation type gel breaker and the biological enzyme gel breaker are isolated by coating films;

the acid gel breaker comprises β -cyclodextrin of 5 parts by weight, citric acid of 8 parts by weight, ethylenediamine tetraacetic acid of 5 parts by weight and sodium hypophosphite of 3 parts by weight;

the oxidation type gel breaker comprises 5 parts by weight of potassium permanganate solution, 1.3 parts by weight of magnesium peroxide, 0.2 part by weight of vegetable oil and 0.06 part by weight of xanthan gum;

the biological enzyme gel breaker comprises 6 parts by weight of l,4- β -D-mannase solution, 0.5 part by weight of glycerol and 0.05 part by weight of gelatin;

the capsule shell comprises 6 parts by weight of xanthan gum, 0.7 part by weight of acrylic resin L100-55 and 0.5 part by weight of glycerol;

the base fluid comprises water, a polyene polyamine organic acid salt and base oil in a weight ratio of 10:0.4: 2;

the preparation method of the microemulsion nano preparation comprises the following steps:

s1, weighing 5 parts by weight of β -cyclodextrin, 8 parts by weight of citric acid, 5 parts by weight of ethylenediamine tetraacetic acid and 3 parts by weight of sodium hypophosphite, dissolving the mixture in 15 parts of water, uniformly stirring, heating to 85 ℃, continuously stirring for 1.5 hours to obtain an acid gel breaker, preparing a sodium alginate solution with the mass fraction of 3.5% by using water and sodium alginate, heating the sodium alginate solution to form a sol state to obtain a sodium alginate colloid, adding the acid gel breaker into the sodium alginate colloid to suspend the acid gel breaker in the sodium alginate colloid to obtain a suspension, then dropwise adding the suspension into a calcium chloride solution with the mass fraction of 2% by using a dropper, slowly stirring clockwise for 13 minutes, and pouring out the calcium chloride solution to obtain a core material;

s2, weighing 5 parts by weight of potassium permanganate solution, uniformly mixing 1.3 parts by weight of magnesium peroxide, 0.2 part by weight of vegetable oil and 0.06 part by weight of xanthan gum to obtain an emulsified oxidation type gel breaker, weighing 6 parts by weight of l,4- β -D-mannase solution, 0.5 part by weight of glycerol and 0.05 part by weight of gelatin, and uniformly stirring to obtain the biological enzyme gel breaker;

step S3, weighing 4 parts by weight of gelatin, 0.4 part by weight of polyethylene glycol, 2 parts by weight of white oil and 8 parts by weight of water, and fully and uniformly stirring to obtain a coating liquid; weighing 6 parts by weight of xanthan gum, 0.7 part by weight of acrylic resin L100-55, 0.5 part by weight of glycerol and 23 parts by weight of water, and uniformly mixing to obtain a capsule shell;

step S4, equally dividing the coating film liquid into two equal parts, putting the nuclear material obtained in the step S1 into a fluidized bed coating machine, and controlling the air pressure in the fluidized bed coating machine to be 0.3MPa and the internal temperature to be 30 ℃ so that the nuclear material forms an annular fluidized state; sequentially filling a first coating film liquid, an oxidation type gel breaker, a second coating film liquid, a biological enzyme gel breaker and a capsule shell into a liquid storage device of a fluidized bed coating machine, sequentially spraying the first coating film liquid, the oxidation type gel breaker, the second coating film liquid, the biological enzyme gel breaker and the capsule shell on a core material through a peristaltic pump to obtain a multilayer coating, keeping an annular fluidization state for 7min after spraying is completed each time, keeping an annular fluidization state for 70min after spraying of the capsule shell is completed, closing an air compressor, taking out the multilayer coating, and air-drying to obtain the microemulsion nano preparation.

< comparative example 10>

The invention provides a strong-inhibition bunching environment-friendly drilling and completion fluid which comprises 85 parts by weight of base fluid, 15 parts by weight of microemulsion nano preparation, 2 parts by weight of plugging anti-collapse agent, 2 parts by weight of oil-soluble temporary plugging agent and 1.0 part by weight of corrosion inhibitor; the micro-emulsion nano preparation comprises an acidic gel breaker, a biological enzyme gel breaker, an oxidation type gel breaker and a capsule shell from inside to outside in sequence; the acid gel breaker, the biological enzyme gel breaker and the oxidation type gel breaker are isolated by coating films;

the acid gel breaker comprises β -cyclodextrin of 5 parts by weight, citric acid of 8 parts by weight, ethylenediamine tetraacetic acid of 5 parts by weight and sodium hypophosphite of 3 parts by weight;

the biological enzyme gel breaker comprises 6 parts by weight of l,4- β -D-mannase solution, 0.5 part by weight of glycerol and 0.05 part by weight of gelatin;

the oxidation type gel breaker comprises 5 parts by weight of potassium permanganate solution, 1.3 parts by weight of magnesium peroxide, 0.2 part by weight of vegetable oil and 0.06 part by weight of xanthan gum;

the capsule shell comprises 6 parts by weight of xanthan gum, 0.7 part by weight of acrylic resin L100-55 and 0.5 part by weight of glycerol;

the base fluid comprises water, a polyene polyamine organic acid salt and base oil in a weight ratio of 10:0.4: 2;

the preparation method of the microemulsion nano preparation comprises the following steps:

s1, weighing 5 parts by weight of β -cyclodextrin, 8 parts by weight of citric acid, 5 parts by weight of ethylenediamine tetraacetic acid and 3 parts by weight of sodium hypophosphite, dissolving the mixture in 15 parts of water, uniformly stirring, heating to 85 ℃, continuously stirring for 1.5 hours to obtain an acid gel breaker, preparing a sodium alginate solution with the mass fraction of 3.5% by using water and sodium alginate, heating the sodium alginate solution to form a sol state to obtain a sodium alginate colloid, adding the acid gel breaker into the sodium alginate colloid to suspend the acid gel breaker in the sodium alginate colloid to obtain a suspension, then dropwise adding the suspension into a calcium chloride solution with the mass fraction of 2% by using a dropper, slowly stirring clockwise for 13 minutes, and pouring out the calcium chloride solution to obtain a core material;

s2, weighing 6 parts by weight of l,4- β -D-mannase solution, 0.5 part by weight of glycerol and 0.05 part by weight of gelatin, and uniformly stirring to obtain a biological enzyme gel breaker, weighing 5 parts by weight of potassium permanganate solution, and uniformly mixing 1.3 parts by weight of magnesium peroxide, 0.2 part by weight of vegetable oil and 0.06 part by weight of xanthan gum to obtain an emulsified oxidation type gel breaker;

step S3, weighing 4 parts by weight of gelatin, 0.4 part by weight of polyethylene glycol, 2 parts by weight of white oil and 8 parts by weight of water, and fully and uniformly stirring to obtain a coating liquid; weighing 6 parts by weight of xanthan gum, 0.7 part by weight of acrylic resin L100-55, 0.5 part by weight of glycerol and 23 parts by weight of water, and uniformly mixing to obtain a capsule shell;

step S4, equally dividing the coating film liquid into two equal parts, putting the nuclear material obtained in the step S1 into a fluidized bed coating machine, and controlling the air pressure in the fluidized bed coating machine to be 0.3MPa and the internal temperature to be 30 ℃ so that the nuclear material forms an annular fluidized state; sequentially filling a first coating film liquid, a biological enzyme gel breaker, a second coating film liquid, an oxidation type gel breaker and a capsule shell into a liquid storage device of a fluidized bed coating machine, sequentially spraying the first coating film liquid, the biological enzyme gel breaker, the second coating film liquid, the oxidation type gel breaker and the capsule shell on a core material through a peristaltic pump to obtain a multilayer coating, keeping an annular fluidization state for 7min after spraying is completed each time, keeping an annular fluidization state for 70min after spraying of the capsule shell is completed, closing an air compressor, taking out the multilayer coating, and air-drying to obtain the microemulsion nano preparation.

< comparative example 11>

The invention provides a strong-inhibition bunching environment-friendly drilling and completion fluid which comprises 85 parts by weight of base fluid, 15 parts by weight of microemulsion nano preparation, 2 parts by weight of plugging anti-collapse agent, 2 parts by weight of oil-soluble temporary plugging agent and 1.0 part by weight of corrosion inhibitor; the micro-emulsion nano preparation comprises an oxidation type gel breaker, an acid gel breaker, a biological enzyme gel breaker and a capsule shell from inside to outside in sequence; the oxidation type gel breaker, the acid gel breaker and the biological enzyme gel breaker are isolated by coating films;

the oxidation type gel breaker comprises 5 parts by weight of potassium permanganate solution, 1.3 parts by weight of magnesium peroxide, 0.2 part by weight of vegetable oil and 0.06 part by weight of xanthan gum;

the acid gel breaker comprises β -cyclodextrin of 5 parts by weight, citric acid of 8 parts by weight, ethylenediamine tetraacetic acid of 5 parts by weight and sodium hypophosphite of 3 parts by weight;

the biological enzyme gel breaker comprises 6 parts by weight of l,4- β -D-mannase solution, 0.5 part by weight of glycerol and 0.05 part by weight of gelatin;

the capsule shell comprises 6 parts by weight of xanthan gum, 0.7 part by weight of acrylic resin L100-55 and 0.5 part by weight of glycerol;

the base fluid comprises water, a polyene polyamine organic acid salt and base oil in a weight ratio of 10:0.4: 2;

the preparation method of the microemulsion nano preparation comprises the following steps:

step S1, weighing 5 parts by weight of potassium permanganate solution, and uniformly mixing 1.3 parts by weight of magnesium peroxide, 0.2 part by weight of vegetable oil and 0.06 part by weight of xanthan gum to obtain the emulsified oxidized gel breaker; preparing a sodium alginate solution with the mass fraction of 3.5% by using water and sodium alginate, heating to enable the sodium alginate solution to be in a sol state to obtain a sodium alginate colloid, adding an oxidation type gel breaker into the sodium alginate colloid to enable the oxidation type gel breaker to be suspended in the sodium alginate colloid to obtain a suspension, then dropwise adding the suspension into a calcium chloride solution with the mass fraction of 2% by using a dropper, slowly stirring for 13min clockwise, and pouring out the calcium chloride solution to obtain a core material;

s2, weighing 5 parts by weight of β -cyclodextrin, 8 parts by weight of citric acid, 5 parts by weight of ethylenediamine tetraacetic acid and 3 parts by weight of sodium hypophosphite, dissolving in 15 parts of water, uniformly stirring, heating to 85 ℃, continuously stirring for 1.5 hours to obtain an acid gel breaker, weighing 6 parts by weight of l,4- β -D-mannase solution, 0.5 part by weight of glycerol and 0.05 part by weight of gelatin, and uniformly stirring to obtain the biological enzyme gel breaker;

step S3, weighing 4 parts by weight of gelatin, 0.4 part by weight of polyethylene glycol, 2 parts by weight of white oil and 8 parts by weight of water, and fully and uniformly stirring to obtain a coating liquid; weighing 6 parts by weight of xanthan gum, 0.7 part by weight of acrylic resin L100-55, 0.5 part by weight of glycerol and 23 parts by weight of water, and uniformly mixing to obtain a capsule shell;

step S4, equally dividing the coating film liquid into two equal parts, putting the nuclear material obtained in the step S1 into a fluidized bed coating machine, and controlling the air pressure in the fluidized bed coating machine to be 0.3MPa and the internal temperature to be 30 ℃ so that the nuclear material forms an annular fluidized state; sequentially filling a first coating film liquid, an acid gel breaker, a second coating film liquid, a biological enzyme gel breaker and a capsule shell into a liquid reservoir of a fluidized bed coating machine, sequentially spraying the first coating film liquid, the acid gel breaker, the second coating film liquid, the biological enzyme gel breaker and the capsule shell on a core material through a peristaltic pump to obtain a multi-layer coating, keeping an annular fluidization state for 7min after spraying is completed each time, closing an air compressor after spraying of the capsule shell is completed, taking out the multi-layer coating, and air-drying to obtain the microemulsion nano preparation.

< comparative example 12>

The invention provides a strong-inhibition bunching environment-friendly drilling and completion fluid which comprises 85 parts by weight of base fluid, 15 parts by weight of microemulsion nano preparation, 2 parts by weight of plugging anti-collapse agent, 2 parts by weight of oil-soluble temporary plugging agent and 1.0 part by weight of corrosion inhibitor; the micro-emulsion nano preparation comprises an oxidation type gel breaker, a biological enzyme gel breaker, an acid gel breaker, a coating mold liquid and a capsule shell;

the oxidation type gel breaker comprises 5 parts by weight of potassium permanganate solution, 1.3 parts by weight of magnesium peroxide, 0.2 part by weight of vegetable oil and 0.06 part by weight of xanthan gum;

the biological enzyme gel breaker comprises 6 parts by weight of l,4- β -D-mannase solution, 0.5 part by weight of glycerol and 0.05 part by weight of gelatin;

the acid gel breaker comprises β -cyclodextrin of 5 parts by weight, citric acid of 8 parts by weight, ethylenediamine tetraacetic acid of 5 parts by weight and sodium hypophosphite of 3 parts by weight;

the capsule shell comprises 6 parts by weight of xanthan gum, 0.7 part by weight of acrylic resin L100-55 and 0.5 part by weight of glycerol;

the base fluid comprises water, a polyene polyamine organic acid salt and base oil in a weight ratio of 10:0.4: 2;

the preparation method of the microemulsion nano preparation comprises the following steps:

step S1, weighing 5 parts by weight of potassium permanganate solution, and uniformly mixing 1.3 parts by weight of magnesium peroxide, 0.2 part by weight of vegetable oil and 0.06 part by weight of xanthan gum to obtain the emulsified oxidized gel breaker;

s2, weighing 6 parts by weight of l,4- β -D-mannase solution, 0.5 part by weight of glycerol and 0.05 part by weight of gelatin, uniformly stirring to obtain a biological enzyme gel breaker, weighing 5 parts by weight of β -cyclodextrin, 8 parts by weight of citric acid, 5 parts by weight of ethylenediamine tetraacetic acid and 3 parts by weight of sodium hypophosphite, dissolving in 15 parts of water, uniformly stirring, heating to 85 ℃, and continuously stirring for 1.5 hours to obtain an acid gel breaker;

step S3, weighing 4 parts by weight of gelatin, 0.4 part by weight of polyethylene glycol, 2 parts by weight of white oil and 8 parts by weight of water, and fully and uniformly stirring to obtain a coating liquid; weighing 6 parts by weight of xanthan gum, 0.7 part by weight of acrylic resin L100-55, 0.5 part by weight of glycerol and 23 parts by weight of water, and uniformly mixing to obtain a capsule shell;

and step S4, mixing the oxidation type gel breaker, the biological enzyme gel breaker, the acidic gel breaker, the coating membrane liquid and the capsule shell, and fully stirring to obtain the microemulsion nano preparation.

< test example >

The preparation method of the environment-friendly drilling and completion fluid with strong inhibition and bunching comprises the following steps: mixing the base material, the micro-emulsion nano preparation, the plugging anti-collapse agent, the oil-soluble temporary plugging agent and the corrosion inhibitor, and fully and uniformly stirring to obtain the drilling and completion fluid, wherein the drilling and completion fluid can be prepared as required;

the completion drilling fluids of example 3 and comparative examples 1 to 12 were prepared according to the above preparation methods, respectively.

Performing performance tests on the drilling completion fluids prepared in examples 1-3 and comparative examples 1-12 according to the following test methods; the test results are shown in table 1;

1. mud cake removal efficiency: preparing mud cake with conventional drilling fluid under high temperature and high pressure conditions by using a filter loss instrument (for example, aging 5.0% bentonite slurry for 16h, placing into the filter loss instrument, adjusting temperature to 150 deg.C and pressure to 5MPa, performing filter pressing, and discharging after filtrationPressing to obtain mud cakes), removing the floating soil on the surface of the mud cakes, drying, weighing and recording as Q ₁(ii) a Soaking the dried mud cake into the well completion fluid prepared by the invention, standing for 24h, taking out, naturally drying, weighing and recording as Q ₂The mud cake clearance rate A ═ Q (Q) ₁-Q ₂)/Q ₁*100％。

2. And (3) the core permeability recovery rate: drilling a standard core of 25mm multiplied by L and 50mm, measuring the actual diameter and length of the standard core, and placing the core in an oven for drying; evacuating the dried core by using a vacuum pump, and simultaneously measuring the porosity; then putting the rock core into a rock core flow test device, positively displacing the rock core by kerosene under the action of pressurization until the displacement volume is 20-50 times larger than the pore volume and the pressure is relatively constant, and then measuring the permeability of the rock core and recording the permeability as K ₁(ii) a Then, reversely displacing the kerosene in the core by using the completion fluid prepared by the method until the displacement volume is 20-50 times larger than the pore volume and the pressure is relatively constant, then positively displacing the completion fluid in the core by using the kerosene until the displacement volume is 20-50 times larger than the pore volume and the pressure is relatively constant, and measuring the permeability at the moment and marking the permeability as K ₂(ii) a Core permeability recovery rate K ═ K ₂/K ₁×100％。

3. The filtration loss: the measurement (temperature: 25 ℃) and the calculation of the fluid loss were carried out by referring to the method defined in SY/T5241-91.

4. Corrosion rate: the corrosion rate was measured according to GB/T18175-2000 at 45 ℃ for a 48h soak time.

5. Relative expansion ratio: weighing clay ag (accurate to 0.01g) dried to constant weight, pouring clay into clean and dry graduated cylinder with plug, lightly shaking, reading clay volume, and recording as V ₀(ii) a Then, a completion fluid (10mL/1g clay) is poured into the measuring cylinder, the measuring cylinder is fully shaken up, the measuring cylinder is kept stand for 24 hours at room temperature, and the volume of the clay is read and recorded as V ₁(ii) a Shaking for 5 times, wherein the shaking time is 0.5h, 1h, 2h, 6h and 8h after completion fluid is added;

simultaneously, tap water is used for a blank experiment, water with the same volume as the completion fluid is measured to replace the completion fluid, and after standing for 24 hours, the volume of the clay is marked as V ₂(ii) a Relative expansionExpansion ratio psi [ (V) ] ₁-V ₀)/(V ₂-V ₀)]×100％。

Table 1 results of performance testing

As can be seen from table 1, compared with comparative examples 1 to 12, the drilling and completion fluid prepared in embodiment 3 of the present invention has a higher mud cake removal efficiency, which is up to 93%, and the core permeability recovery rate is also up to 95%, which indicates that the drilling and completion fluid prepared in embodiment 3 of the present invention can completely remove mud cakes and remove choke plugs, so that oil can rapidly seep out, and further the oil production performance is improved, and meanwhile, the drilling and completion fluid prepared in embodiment 3 of the present invention has a lower filtration loss, corrosion performance and relative expansion rate, so that a reservoir stratum is well protected;

compared with the comparative examples 7-11, the wrapping sequence of the three gel breakers is different from that of the example 3, and the obtained drilling and completing fluid has weaker performances than that of the example 3, so that the acid gel breaker, the biological enzyme gel breaker and the oxidation gel breaker are firstly carried out, the removing effect is better, the reservoir is hardly damaged, and the acidic gel breaker and the oxidation gel breaker are in contact with each other to react and further reduce the performances of the drilling and completing fluid;

comparative examples 4-6 and comparative examples 1-3 show that the performance of the drilling completion fluid prepared by using any two of the three gel breakers in a layer-by-layer wrapping manner or using only one gel breaker is inferior to that of example 3, so that the three gel breakers are matched with each other, and are gradually released layer by layer, and the performance of the drilling completion fluid can be greatly improved;

comparative example 12 is that three gel breakers are simply mixed without being isolated, and the problem that the three gel breakers fail due to interaction exists, so that various performances of the drilling and completion fluid are greatly reduced;

the number of apparatuses and the scale of the process described herein are intended to simplify the description of the present invention. Applications, modifications and variations of the present invention will be apparent to those skilled in the art.

While embodiments of the invention have been disclosed above, it is not limited to the applications listed in the description and the embodiments, which are fully applicable in all kinds of fields of application of the invention, and further modifications may readily be effected by those skilled in the art, so that the invention is not limited to the specific details without departing from the general concept defined by the claims and the scope of equivalents.