CN111592868A - A fracturing fluid and its preparation method and application - Google Patents

Abstract

The invention provides a fracturing fluid and a preparation method and application thereof, wherein the fracturing fluid comprises the following components in parts by weight: 20-80 parts of organic salt weighting agent; 0.3-0.5 weight part of thickening agent; 0.3-1.0 part by weight of a crosslinking agent; 0.1-1.2 parts of temperature stabilizer; 0.1 to 0.5 part by weight of a delayed crosslinking agent; 0.2-0.5 part by weight of pH regulator; 0.1-0.2 parts of bactericide; 0.01-0.05 part by weight of cosolvent; 0.1-0.5 parts of gel breaker; 100 parts of water. The fracturing fluid is used for the development of high-pressure wells, deep wells, ultra-deep wells and compact oil and gas reservoirs, the fracturing effect is obviously improved, and the oil and gas productivity is increased. The fracturing fluid has higher density and adjustable density, can be safely applied to the development of high-pressure wells, deep wells, ultra-deep wells and compact oil-gas reservoirs, obviously improves the fracturing effect, and increases the oil-gas productivity.

Description

A fracturing fluid and its preparation method and application

technical field

The invention relates to a fracturing fluid, a preparation method and application thereof, and belongs to the technical field of oil and natural gas production stimulation.

Background technique

With the continuous deepening of oil and gas field exploration and development, hydraulic fracturing technology is an important technical means for oil and gas field testing and development in the process of oil and natural gas exploration and development. As more and more deep wells, high pressure wells and high stress wells are fracturing reservoirs, the difficulty of excessively high construction pressure generally exists, thus reducing the success rate of fracturing construction.

At this stage, there are three methods to reduce the high construction pressure. The first is to use high-pressure wellhead and surface equipment. Therefore, domestic deep fracturing construction has generally been equipped with high-pressure equipment; the second is to use large-diameter pipe strings to reduce the friction of fracturing fluid, but large-diameter pipe strings are usually limited by the wellbore structure, and the wellbore structure is adjusted at the same time. It is necessary to increase the drilling cost; the third is to use heavier fracturing fluid, that is, to increase the density of the fracturing fluid, increase the density of the liquid column, and reduce the wellhead pressure. At present, increasing the liquid column pressure by using high-density fracturing fluid is an important means to reduce the pump pressure of fracturing construction.

Existing high-density fracturing fluids mainly use halogen salt weighting agents, such as sodium chloride, potassium chloride, sodium bromide or sodium nitrate, as weighting agents to increase the density of the fracturing fluid. However, the cost of the weighted fracturing fluid based on sodium bromide is too high, which will cause damage to the human body, organisms and the environment. It is subject to many restrictions in practical applications and is currently rarely used; halogen salt weighting agents (sodium chloride, sodium chloride, Potassium chloride) to increase the efficiency of fracturing fluid, the density of the prepared brine does not exceed 1.15g/cm ³ , and it is easy to crystallize at low temperature, and the presence of a large number of halogen ions will also cause serious corrosion to completion pipes, which cannot meet ultra-deep well pressure. The need for fracturing; the fracturing fluid using sodium nitrate as a weighting agent has strong corrosiveness, which will cause corrosion to the fracturing equipment and the oil production equipment after fracturing. Therefore, providing a safe and high-density fracturing fluid suitable for high-pressure wells, deep wells, ultra-deep wells and tight oil and gas reservoirs is an urgent problem to be solved in the art.

SUMMARY OF THE INVENTION

The invention provides a fracturing fluid, a preparation method and application thereof. The fracturing fluid has high density and adjustable density, can be safely applied to the development of high-pressure wells, deep wells, ultra-deep wells and tight oil and gas reservoirs, and significantly improves the fracturing fluid. cracking effect and increase oil and gas production capacity.

The present invention provides a fracturing fluid, comprising the following components according to parts by weight:

20-80 parts by weight of organic salt weighting agent;

Thickener 0.3-0.5 parts by weight;

0.3-1.0 parts by weight of cross-linking agent;

Temperature stabilizer 0.1-1.2 parts by weight;

0.1-0.5 parts by weight of delayed cross-linking agent;

0.2-0.5 parts by weight of pH regulator;

Fungicide 0.1-0.2 parts by weight;

Cosolvent 0.01-0.05 parts by weight;

0.1-0.5 parts by weight of breaker;

100 parts by weight of water.

The above fracturing fluid, wherein the organic salt weighting agent is an organic salt containing an alkali metal element or an alkaline earth metal element.

The above fracturing fluid, wherein the alkali metal element is potassium metal, and the alkaline earth metal is sodium metal.

The above fracturing fluid, wherein the organic salt weighting agent is selected from one or more of sodium formate, potassium formate, potassium acetate and potassium citrate.

The above fracturing fluid, wherein the thickening agent is selected from hydroxypropyl guar gum or modified guar gum.

The above fracturing fluid, wherein the crosslinking agent is an organic boron compound.

The above fracturing fluid, wherein the pH adjuster is selected from one of sodium carbonate, sodium bicarbonate and sodium hydroxide.

The fracturing fluid as described above, wherein the fracturing fluid has a density of 1.2-1.4 g/cm ³ and a pH of 10-12.

The present invention also provides a method for preparing the fracturing fluid described above, comprising the following steps:

1) add organic salt weighting agent, thickening agent, cosolvent to water, and stir to obtain the first solution;

2) adding a pH regulator to the first solution, stirring to obtain a second solution, the pH value of the second solution being 10-12;

3) adding temperature stabilizer, delayed crosslinking agent and bactericide to the second solution, stirring to obtain the third solution;

4) Adding a crosslinking agent and a gel breaker to the third solution at the same time, and stirring, to obtain the fracturing fluid.

The present invention also provides an application of any one of the above-mentioned fracturing fluids in the process of oil and gas exploration and development.

The implementation of the present invention at least includes the following advantages:

1. The fracturing fluid of the present invention has a density of 1.2-1.4 g/cm ³ , and the fracturing fluid density is adjustable, so the fracturing fluid of the present invention can not only effectively fracturing high-pressure wells, deep wells, ultra-deep wells and tight oil and gas reservoirs It can also significantly reduce the pump pressure of fracturing construction and reduce the energy consumption of fracturing;

2. The fracturing fluid of the present invention has good temperature resistance, so it can be used for the exploitation of oil and gas wells with high temperature;

3. The fracturing fluid of the present invention has the characteristics of delayed cross-linking, so it can reduce the friction along the process of high-speed pumping of the fracturing fluid, improve the fracturing efficiency, and further reduce the fracturing energy consumption;

4. The organic salt weighting agent used in the fracturing fluid of the present invention is non-toxic, harmless and biodegradable, which greatly reduces the pollution to the environment;

5. The preparation method of the fracturing fluid of the present invention is simple and feasible, does not require the assistance of large-scale instruments, and is suitable for large-scale popularization and application in the field of oil and gas exploitation.

Description of drawings

Fig. 1 is the flow chart of the preparation method of fracturing fluid of the present invention;

Fig. 2 is the temperature and shear resistance performance curve diagram of the fracturing fluid in the embodiment of the present invention 1;

FIG. 3 is a graph showing the temperature and shear resistance performance of the fracturing fluid in Example 2 of the present invention.

Detailed ways

In order to make the purpose, technical solutions and advantages of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are part of the implementation of the present invention. examples, but not all examples. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

The present invention provides a fracturing fluid, comprising the following components according to parts by weight:

20-80 parts by weight of organic salt weighting agent;

Thickener 0.3-0.5 parts by weight;

0.3-1.0 parts by weight of cross-linking agent;

Temperature stabilizer 0.1-1.2 parts by weight;

0.1-0.5 parts by weight of delayed cross-linking agent;

0.2-0.5 parts by weight of pH regulator;

Fungicide 0.1-0.2 parts by weight;

Cosolvent 0.01-0.05 parts by weight;

0.1-0.5 parts by weight of breaker;

100 parts by weight of water.

The fracturing fluid of the present invention is composed of the above components, wherein the organic salt weighting agent is a salt composed of an organic acid anion and a metal cation.

The addition of organic salt weighting agent can increase the density of the fracturing fluid to increase the hydrostatic column pressure of the fracturing fluid, so that the wellhead construction pressure can be greatly reduced in the whole process of construction, and the fracturing operation pressure of deep high temperature reservoirs can be avoided. The occurrence of the problem of exceeding the pressure limit of the equipment construction.

Thickeners can increase the viscosity of drilling fluids, reduce the filtration rate of drilling fluids, and can suspend sand and carry proppants.

The cross-linking agent can cross-link with the thickener in the fracturing fluid through chemical bonds or coordination bonds, thereby generating a high polymer with a network structure. Bound in it, so that the fracturing pressure can be effectively utilized and the fracturing effect can be enhanced.

Since the fracturing fluid of the present invention is mainly aimed at reservoir fracturing of deep wells and high-pressure wells, the liquid flow resistance can be reduced by the cross-linking retarder, thereby further reducing the pump pressure of fracturing construction.

The pH adjuster is used to adjust the pH of the fracturing fluid to support the pH required for the crosslinking reaction of the crosslinking agent.

Bactericide is a kind of chemical additive to prevent the deterioration of fracturing fluid caused by various pathogenic microorganisms. It can prolong the storage time of fracturing fluid and prevent the reproduction of bacteria in the formation.

The co-solvent can increase the solubility of various components in solvent water, which helps the fracturing fluid to form a uniform system, which is not only convenient for the injection of the fracturing fluid to the bottom of the well, but also beneficial for the various functional components in the fracturing fluid. Functional balance.

Breakers help the fracturing fluid degrade and flow back out of the fracture to the surface.

In the present invention, the types of raw materials of the fracturing fluid are limited above, and the ratios of various raw materials are also limited, so that the raw materials can have good compatibility performance and maximize the functionality of various raw materials. It is worth noting that the organic salt weighting agent used in the present invention can exert a certain cross-linking effect, thereby reducing the proportion of the cross-linking agent in the fracturing fluid without affecting the cross-linking reaction, and reducing the impact on the reservoir. pollution. In addition, the organic salt weighting agent is non-toxic and harmless, and can carry out biological reduction, thereby further meeting the demand for environmental protection.

In addition, the fracturing fluid generated in the above proportions also has a certain high temperature resistance, even under the formation of 140 ° C, it still has good thermal stability and shear stability, that is, the fracturing fluid under high temperature and mechanical shear, Viscosity does not decrease significantly, thereby delaying cross-linking and facilitating high temperature reservoir fracturing in deep and ultra-deep wells.

Further, the organic salt weighting agent is an organic salt containing an alkali metal element or an alkaline earth metal element.

Wherein, the organic salt containing an alkali metal element or an alkaline earth metal element means that the anion is an organic acid radical with 1-6 carbon atoms, and the cation is a salt of an alkali metal element or an alkaline earth metal element.

Further, the alkali metal element is potassium metal, and the alkaline earth metal is sodium metal.

Further, the organic salt weighting agent is selected from one or more of sodium formate, potassium formate, potassium acetate and potassium citrate.

When the organic salt weighting agent is a mixture of the above at least two compounds, the present invention does not limit the ratio between the individual compounds.

Further, the thickening agent is selected from hydroxypropyl guar gum or modified guar gum.

Further, the crosslinking agent is an organic boron compound.

Further, the pH adjusting agent is selected from one of sodium carbonate, sodium bicarbonate and sodium hydroxide.

Further, the temperature stabilizer is selected from one or more of sodium thiosulfate, short-chain alcohols and short-chain aldehydes, and short-chain alcohols and short-chain aldehydes refer to alcohols or aldehydes with 1-4 carbon atoms;

Further, the gel breaker is ammonium persulfate;

Further, the delayed cross-linking agent is selected from sodium carbonate or sodium hydrogen hydrochloride;

Further, the bactericide is selected from formaldehyde;

Further, the cosolvent is selected from citric acid.

The fracturing fluid of the invention has a density of 1.2-1.4 g/cm ³ and a pH value of 10-12, and can prepare a fracturing fluid of suitable density according to the site construction environment and reservoir conditions.

Fig. 1 is a flow chart of the preparation method of the fracturing fluid of the present invention. As shown in Fig. 1, the preparation method of the fracturing fluid of the present invention comprises the following steps:

S101: adding an organic salt weighting agent, a thickening agent, and a cosolvent to the water, and stirring to obtain a first solution;

S102: adding a pH regulator to the first solution to obtain a second solution, and the pH value of the second solution is 10-12;

S103: adding a temperature stabilizer, a delayed crosslinking agent and a bactericide to the second solution, and stirring to obtain a third solution;

S104: Add a crosslinking agent and a gel breaker to the third solution simultaneously, and stir to obtain a fracturing fluid.

In S101, after the organic salt weighting agent is adjusted to the target density, the thickening agent and the cosolvent are added in sequence, and stirring is performed, and the stirring time is 30-120 min.

It is worth noting that a series of parameter tests and tests can be performed on the fracturing fluid prepared by the above method in the laboratory, while in specific applications, the third solution in S103 needs to be mixed with a breaker, and the mixture The solution and the cross-linking agent are pumped into the bottom of the well through the cross-linking pump at the same time, so that the two are cross-linked at the bottom of the well to generate fracturing fluid.

The present invention also provides an application of any one of the above-mentioned fracturing fluids in the process of oil and gas exploration and development. Especially in high pressure wells, deep wells, ultra-deep wells and tight oil and gas reservoirs.

Hereinafter, the fracturing fluid and the preparation method thereof in the present invention will be introduced in detail through specific examples.

Example 1

The fracturing fluid of the present embodiment, the raw material composition includes:

Water: 100 parts by weight

Organic salt weighting agent: 46 parts by weight of potassium formate

Thickener: 0.4 parts by weight of hydroxypropyl guar;

Temperature stabilizer: 1 part by weight of sodium thiosulfate, 0.1 part by weight of propanol;

Crosslinking agent: 0.5 parts by weight of organoboron compound

pH adjuster: 0.3 part by weight of sodium carbonate

Gel breaker: 0.1 part by weight of ammonium persulfate

Delayed cross-linking agent: 0.1 part by weight of sodium bicarbonate

Bactericide: 0.1 parts by weight of formaldehyde

Cosolvent: 0.025 parts by weight of citric acid

The preparation method of the fracturing fluid of the present embodiment comprises the following steps:

1) Add water to the liquid preparation tank, add organic salt weighting agent under the condition of circulating stirring, stir until it is completely dissolved, and adjust the fracturing fluid density to meet the construction requirements;

Then add thickening agent and co-solvent to circulate and stir for 60min to fully dissolve and swell the thickening agent to form the first solution;

2) adding a pH regulator to the first solution, making the pH value 10, and stirring to obtain the second solution;

3) adding temperature stabilizer, bactericide, delayed cross-linking agent to the third solution, stirring, to obtain the third solution; the viscosity of the third solution is 54mPa s after testing, and 3 minutes is hung;

4) Adding a crosslinking agent and a gel breaker to the third solution at the same time to obtain the fracturing fluid of this embodiment.

After testing, the density of the fracturing fluid in this embodiment is 1.30 g/cm ³ ;

After testing, the cross-linking time of the fracturing fluid in this embodiment is 10 minutes;

The fracturing fluid was sheared for 120 min at a temperature of 140° C. and 170 S ⁻¹ , and the final viscosity of the fracturing fluid was 143.6 mPa·s.

Figure 2 is a graph showing the temperature and shear resistance of the fracturing fluid in Example 1 of the present invention. It can be seen from Figure 2 that the weighted fracturing fluid formulation has excellent high temperature resistance and can be used for high temperature reservoir layers in deep and ultra-deep wells crack.

Example 2

The fracturing fluid of the present embodiment, the raw material composition includes:

Water: 100 parts by weight

Organic salt weighting agent: 46 parts by weight of potassium formate

Thickener: 0.4 parts by weight of hydroxypropyl guar;

Temperature stabilizer: 1 part by weight of sodium thiosulfate, 0.1 part by weight of propanol;

Crosslinking agent: 0.6 parts by weight of organoboron compound

pH adjuster: 0.2 part by weight of sodium bicarbonate

Gel breaker: 0.1 part by weight of ammonium persulfate

Delayed cross-linking agent: 0.2 parts by weight of sodium bicarbonate

Bactericide: 0.1 parts by weight of formaldehyde

Cosolvent: 0.025 parts by weight of citric acid

The preparation method of the fracturing fluid of the present embodiment comprises the following steps:

1) Add water to the liquid preparation tank, add organic salt weighting agent under the condition of circulating stirring, stir until it is completely dissolved, and adjust the fracturing fluid density to meet the construction requirements;

Then add thickening agent and co-solvent to circulate and stir for 60min to fully dissolve and swell the thickening agent to form the first solution;

2) adding a pH regulator to the first solution, making the pH value 10, and stirring to obtain the second solution;

3) adding temperature stabilizer, bactericide, delayed cross-linking agent in the third solution, stirring, to obtain the third solution; the viscosity of the third solution is 60mPa s after detection, and 7 minutes hangs;

4) Adding a crosslinking agent and a gel breaker to the third solution at the same time to obtain the fracturing fluid of this embodiment.

After testing, the density of the fracturing fluid in this embodiment is 1.30 g/cm ³ ;

After testing, the cross-linking time of the fracturing fluid in this embodiment is 7min;

The fracturing fluid was sheared at a temperature of 140° C. and 170 S ⁻¹ for 120 min, and the final viscosity of the fracturing fluid was 117.8 mPa·s.

Figure 3 is a graph showing the temperature and shear resistance performance of the fracturing fluid in Example 2 of the present invention. It can be seen from Figure 3 that the weighted fracturing fluid formulation has excellent high temperature resistance and can be used for high temperature reservoir layers in deep and ultra-deep wells crack.

Example 3

The fracturing fluid of the present embodiment, the raw material composition includes:

Water: 100 parts by weight

Organic salt weighting agent: 50 parts by weight of sodium formate

Thickener: 0.4 parts by weight of hydroxypropyl guar;

Temperature stabilizer: 1 part by weight of sodium thiosulfate, 0.1 part by weight of glycerin;

Crosslinking agent: 0.6 parts by weight of organoboron compound

pH adjuster: 0.3 part by weight of sodium carbonate

Gel breaker: 0.1 part by weight of ammonium persulfate

Delayed cross-linking agent: 0.2 parts by weight of sodium bicarbonate

Bactericide: 0.1 parts by weight of formaldehyde

Cosolvent: 0.025 parts by weight of citric acid

The preparation method of the fracturing fluid of the present embodiment comprises the following steps:

1) Add water to the liquid preparation tank, add organic salt weighting agent under the condition of circulating stirring, stir until it is completely dissolved, and adjust the fracturing fluid density to meet the construction requirements;

Then add thickening agent and co-solvent to circulate and stir for 60min to fully dissolve and swell the thickening agent to form the first solution;

2) adding a pH regulator to the first solution, making the pH value 11, and stirring to obtain a second solution;

3) adding temperature stabilizer, bactericide, delayed cross-linking agent in the third solution, stirring, to obtain the third solution; the viscosity of the third solution is 58mPa s after testing, and 5 minutes hangs;

4) Adding a crosslinking agent and a gel breaker to the third solution at the same time to obtain the fracturing fluid of this embodiment.

After testing, the density of the fracturing fluid in this embodiment is 1.30 g/cm ³ ;

After testing, the cross-linking time of the fracturing fluid in this embodiment is 5 minutes;

The fracturing fluid was sheared at a temperature of 140° C. and 170 S ⁻¹ for 120 min, and the final viscosity of the fracturing fluid was 115.6 mPa·s.

Example 4

The fracturing fluid of the present embodiment, the raw material composition includes:

Water: 100 parts by weight

Organic salt weighting agent: 35 parts by weight of sodium formate, 9 parts by weight of potassium formate

Thickener: 0.4 parts by weight of hydroxypropyl guar;

Temperature stabilizer: 1 part by weight of sodium thiosulfate, 0.1 part by weight of glycerin;

Crosslinking agent: 0.6 parts by weight of organoboron compound

pH adjuster: 0.3 part by weight of sodium carbonate

Gel breaker: 0.1 part by weight of ammonium persulfate

Delayed cross-linking agent: 0.2 parts by weight of sodium bicarbonate

Bactericide: 0.1 parts by weight of formaldehyde

Cosolvent: 0.025 parts by weight of citric acid

The preparation method of the fracturing fluid of the present embodiment comprises the following steps:

1) Add water to the liquid preparation tank, add organic salt weighting agent under the condition of circulating stirring, stir until it is completely dissolved, and adjust the fracturing fluid density to meet the construction requirements;

Then add thickening agent and co-solvent to circulate and stir for 60min to fully dissolve and swell the thickening agent to form the first solution;

2) adding a pH regulator to the first solution, making the pH value 11, and stirring to obtain a second solution;

3) in the third solution, add temperature stabilizer, bactericide, delayed crosslinking agent, stir to obtain the third solution; The viscosity of the third solution is detected to be 57mPa s, and 6 minutes to hang;

4) Adding a crosslinking agent and a gel breaker to the third solution at the same time to obtain the fracturing fluid of this embodiment.

After testing, the density of the fracturing fluid in this embodiment is 1.30 g/cm ³ ;

After testing, the cross-linking time of the fracturing fluid in this embodiment is 6 minutes;

The fracturing fluid was sheared at a temperature of 140° C. and 170 S ⁻¹ for 120 min, and the final viscosity of the fracturing fluid was 125.5 mPa·s.

Example 5

The fracturing fluid of the present embodiment, the raw material composition includes:

Water: 100 parts by weight

Organic salt weighting agent: 52 parts by weight of potassium formate

Thickener: 0.45 parts by weight of hydroxypropyl guar;

Temperature stabilizer: 1 part by weight of sodium thiosulfate, 0.1 part by weight of glycerin;

Crosslinking agent: 0.65 parts by weight of organic boron compound

pH adjuster: 0.35 parts by weight of sodium carbonate

Gel breaker: 0.2 parts by weight of ammonium persulfate

Delayed cross-linking agent: 0.3 parts by weight of sodium bicarbonate

Bactericide: 0.1 parts by weight of formaldehyde

Cosolvent: 0.025 parts by weight of citric acid

The preparation method of the fracturing fluid of the present embodiment comprises the following steps:

1) Add water to the liquid preparation tank, add organic salt weighting agent under the condition of circulating stirring, stir until it is completely dissolved, and adjust the fracturing fluid density to meet the construction requirements;

Then add thickening agent and co-solvent to circulate and stir for 60min to fully dissolve and swell the thickening agent to form the first solution;

2) adding a pH regulator to the first solution, making the pH value 10, and stirring to obtain the second solution;

3) adding temperature stabilizer, bactericide, delayed cross-linking agent in the third solution, stirring, to obtain the third solution; The viscosity of the third solution is detected to be 65mPa s, and 8 minutes to hang;

4) Adding a crosslinking agent and a gel breaker to the third solution at the same time to obtain the fracturing fluid of this embodiment.

After testing, the density of the fracturing fluid in this embodiment is 1.35g/cm ³ ;

After testing, the cross-linking time of the fracturing fluid in this embodiment is 8 minutes;

The fracturing fluid was sheared at a temperature of 140° C. and 170 S ⁻¹ for 120 min, and the final viscosity of the fracturing fluid was 132.5 mPa·s.

Example 6

The fracturing fluid of the present embodiment, the raw material composition includes:

Water: 100 parts by weight

Organic salt weighting agent: 57 parts by weight of potassium formate

Thickener: 0.5 parts by weight of hydroxypropyl guar;

Temperature stabilizer: 1 part by weight of sodium thiosulfate, 0.2 part by weight of glycerol;

Crosslinking agent: 0.8 parts by weight of organoboron compound

pH adjuster: 0.4 parts by weight of sodium carbonate

Gel breaker: 0.3 parts by weight of ammonium persulfate

Delayed cross-linking agent: 0.2 parts by weight of sodium bicarbonate

Bactericide: 0.1 parts by weight of formaldehyde

Cosolvent: 0.025 parts by weight of citric acid

The preparation method of the fracturing fluid of the present embodiment comprises the following steps:

1) Add water to the liquid preparation tank, add organic salt weighting agent under the condition of circulating stirring, stir until it is completely dissolved, and adjust the fracturing fluid density to meet the construction requirements;

Then add thickening agent and co-solvent to circulate and stir for 60min to fully dissolve and swell the thickening agent to form the first solution;

2) adding a pH regulator to the first solution, making the pH value 10, and stirring to obtain the second solution;

3) adding temperature stabilizer, bactericide, delayed cross-linking agent in the third solution, stirring, to obtain the third solution; The viscosity of the third solution is detected to be 65mPa s, and 9 minutes to hang;

4) Adding a crosslinking agent and a gel breaker to the third solution at the same time to obtain the fracturing fluid of this embodiment.

After testing, the density of the fracturing fluid in this embodiment is 1.40 g/cm ³ ;

After testing, the cross-linking time of the fracturing fluid in this embodiment is 9 min;

The fracturing fluid was sheared at a temperature of 140° C. and 170 S ⁻¹ for 120 min, and the final viscosity of the fracturing fluid was 132.5 mPa·s.

Example 7

The fracturing fluid of the present embodiment, the raw material composition includes:

Water: 100 parts by weight

Organic salt weighting agent: 39 parts by weight of potassium formate

Thickener: 0.35 parts by weight of hydroxypropyl guar;

Temperature stabilizer: 1 part by weight of sodium thiosulfate, 0.2 part by weight of glycerol;

Crosslinking agent: 0.6 parts by weight of organoboron compound

pH adjuster: 0.4 parts by weight of sodium carbonate

Gel breaker: 0.1 part by weight of ammonium persulfate

Delayed cross-linking agent: 0.2 parts by weight of sodium bicarbonate

Bactericide: 0.1 parts by weight of formaldehyde

Cosolvent: 0.025 parts by weight of citric acid

The preparation method of the fracturing fluid of the present embodiment comprises the following steps:

1) Add water to the liquid preparation tank, add organic salt weighting agent under the condition of circulating stirring, stir until it is completely dissolved, and adjust the fracturing fluid density to meet the construction requirements;

Then add thickening agent and co-solvent to circulate and stir for 60min to fully dissolve and swell the thickening agent to form the first solution;

2) adding a pH regulator to the first solution, making the pH value 10, and stirring to obtain the second solution;

3) adding temperature stabilizer in the third solution, bactericide, delayed cross-linking agent, stirring, to obtain the third solution; The viscosity of the third solution is detected to be 55mPa s, and 10 minutes to hang;

4) Adding a crosslinking agent and a gel breaker to the third solution at the same time to obtain the fracturing fluid of this embodiment.

After testing, the density of the fracturing fluid in this embodiment is 1.20 g/cm ³ ;

After testing, the cross-linking time of the fracturing fluid in this embodiment is 10 minutes;

The fracturing fluid was sheared at a temperature of 140° C. and 170 S ⁻¹ for 120 min, and the final viscosity of the fracturing fluid was 126.7 mPa·s.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, but not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: The technical solutions described in the foregoing embodiments can still be modified, or some or all of the technical features thereof can be equivalently replaced; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the technical solutions of the embodiments of the present invention. scope.

Claims (10)

1. a fracturing fluid, is characterized in that, comprises following components according to weight part: 20-80 parts by weight of organic salt weighting agent; Thickener 0.3-0.5 parts by weight; 0.3-1.0 parts by weight of cross-linking agent; 0.1-1.2 parts by weight of temperature stabilizer; 0.1-0.5 parts by weight of delayed cross-linking agent; 0.2-0.5 parts by weight of pH regulator; Fungicide 0.1-0.2 parts by weight; Cosolvent 0.01-0.05 parts by weight; 0.1-0.5 parts by weight of breaker; 100 parts by weight of water. 2 . The fracturing fluid according to claim 1 , wherein the organic salt weighting agent is an organic salt containing an alkali metal element or an alkaline earth metal element. 3 . 3. The fracturing fluid according to claim 2, wherein the alkali metal element is potassium metal, and the alkaline earth metal is sodium metal. 4. The fracturing fluid according to claim 3, wherein the organic salt weighting agent is selected from one or more of sodium formate, potassium formate, potassium acetate and potassium citrate. 5. The fracturing fluid according to claim 1, wherein the thickening agent is selected from hydroxypropyl guar gum or modified guar gum. 6. The fracturing fluid according to claim 1, wherein the crosslinking agent is an organoboron compound. 7. The fracturing fluid according to claim 1, wherein the pH adjusting agent is selected from the group consisting of sodium carbonate, sodium bicarbonate and sodium hydroxide. 8 . The fracturing fluid according to claim 1 , wherein the fracturing fluid has a density of 1.2-1.4 g/cm ³ and a pH of 10-12. 9 . 9. the preparation method of the arbitrary described fracturing fluid of claim 1-8, is characterized in that, comprises the following steps: 1) add organic salt weighting agent, thickening agent, cosolvent to water, and stir to obtain the first solution; 2) adding a pH regulator to the first solution, stirring to obtain a second solution, the pH value of the second solution being 10-12; 3) adding temperature stabilizer, delayed crosslinking agent and bactericide to the second solution, stirring to obtain the third solution; 4) Adding a crosslinking agent and a gel breaker to the third solution at the same time, and stirring, to obtain the fracturing fluid. 10. The application of the fracturing fluid according to any one of claims 1-8 in the process of oil and gas exploration and development.

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