阅读说明：本技术 一种压裂液及其制备方法和应用 (Fracturing fluid and preparation method and application thereof ) 是由 杨向同 袁学芳 冯觉勇 刘会锋 刘举 徐文圣 张杨 黄龙藏 巴旦 刘源 任慧宁 于 2019-02-20 设计创作，主要内容包括：本发明提供一种压裂液及其制备方法和应用,该压裂液按照重量份包括以下组分：有机盐加重剂20-80重量份；稠化剂0.3-0.5重量份；交联剂0.3-1.0重量份；温度稳定剂0.1-1.2重量份；延迟交联剂0.1-0.5重量份；pH调节剂0.2-0.5重量份；杀菌剂0.1-0.2重量份；助溶剂0.01-0.05重量份；破胶剂0.1-0.5重量份；水100重量份。用于高压井、深井、超深井和致密油气藏的开发,显著提高压裂效果,增加油气产能。该压裂液具有较高密度且密度可调,能够安全的应用于高压井、深井、超深井和致密油气藏的开发,显著提高压裂效果,增加油气产能。(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.)

1. The fracturing fluid is characterized by comprising 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.

2. The fracturing fluid of claim 1, wherein the organic salt weighting agent is an organic salt comprising an alkali metal element or an alkaline earth metal element.

3. The fracturing fluid of claim 2, wherein the alkali metal element is potassium metal and the alkaline earth metal is sodium metal.

4. The fracturing fluid of claim 3, wherein the organic salt weighting agent is selected from one or more of sodium formate, potassium acetate, and potassium citrate.

5. The fracturing fluid of claim 1, wherein the viscosifying agent is selected from hydroxypropyl guar or modified guar.

6. The fracturing fluid of claim 1, wherein the crosslinking agent is an organoboron compound.

7. The fracturing fluid of claim 1, wherein the pH modifier is selected from one of sodium carbonate, sodium bicarbonate, and sodium hydroxide.

8. The fracturing fluid of any of claims 1 to 7, wherein the fracturing fluid has a density of 1.2 to 1.4g/cm³The pH value is 10-12.

9. A method of preparing the fracturing fluid of any of claims 1 to 8, comprising the steps of:

1) adding an organic salt weighting agent, a thickening agent and a cosolvent into water, and stirring to obtain a first solution;

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

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

4) and simultaneously adding a cross-linking agent and a gel breaker into the third solution, and stirring to obtain the fracturing fluid.

10. Use of the fracturing fluid of any of claims 1 to 8 in oil and gas exploration and development processes.

Technical Field

The invention relates to a fracturing fluid and a preparation method and application thereof, and belongs to the technical field of petroleum and natural gas yield increase.

Background

With the continuous deepening of the exploration and development of oil and gas fields, the hydraulic fracturing technology is an important technical means for the oil and gas field oil testing and development in the process of the exploration and development of oil and gas. Along with the fracturing transformation of more and more deep wells, high-pressure wells and high-stress wells, the difficulty of overhigh construction pressure generally exists, so that the success rate of fracturing construction is reduced.

At the present stage, three methods can reduce high construction pressure, and the first method is to use a high-pressure-resistant wellhead and ground equipment. Therefore, high-pressure resistant equipment is generally configured in domestic deep fracturing construction; secondly, the friction resistance of the fracturing fluid is reduced by using the configuration of the large-caliber pipe column, but the large-caliber pipe column is usually limited by a well structure, and the well structure is adjusted to increase the drilling cost; thirdly, the heavy fracturing fluid is used, namely the density of the fracturing fluid is improved, the density of a fluid column is increased, and the pressure of a wellhead is reduced. At present, the adoption of high-density fracturing fluid to increase the pressure of a fluid column is an important means for reducing the pumping pressure of fracturing construction.

The existing high-density fracturing fluid mainly adopts a halogen salt weighting agent, such as sodium chloride, potassium chloride, sodium bromide or sodium nitrate, as the weighting agent to improve the density of the fracturing fluid. However, the aggravated fracturing fluid mainly containing sodium bromide has high cost, can cause human bodies, organisms and environments, is limited in practical application, and is rarely applied at present; the efficiency of weighting the fracturing fluid by using a halogen salt weighting agent (sodium chloride and potassium chloride) is not high, and the density of the prepared brine is not more than 1.15g/cm³The low temperature is easy to crystallize, and the existence of a large amount of halogen ions can cause serious corrosion to well completion pipes, so that the requirement of ultra-deep well fracturing cannot be met; the fracturing fluid adopting sodium nitrate as a weighting agent has strong corrosivity and can corrode fracturing equipment and oil extraction equipment after fracturing. Therefore, the problem to be solved in the art is to provide a safe and high-density fracturing fluid suitable for high-pressure wells, deep wells, ultra-deep wells and compact oil and gas reservoirs.

Disclosure of Invention

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 compact oil-gas reservoirs, obviously improves the fracturing effect and increases the oil-gas productivity.

The invention provides a fracturing fluid which 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 as described above, wherein the organic salt weighting agent is an organic salt containing an alkali metal element or an alkaline earth metal element.

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

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

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

The fracturing fluid of the above, wherein the crosslinking agent is an organoboron compound.

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

The fracturing fluid, wherein the density of the fracturing fluid is 1.2-1.4g/cm³The pH value is 10-12.

The invention also provides a preparation method of any one of the fracturing fluids, which comprises the following steps:

1) adding an organic salt weighting agent, a thickening agent and a cosolvent into water, and stirring to obtain a first solution;

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

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

4) and simultaneously adding a cross-linking agent and a gel breaker into the third solution, and stirring to obtain the fracturing fluid.

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

The implementation of the invention at least comprises the following advantages:

1. the density of the fracturing fluid is 1.2-1.4g/cm³And the fracturing fluid has adjustable density, so the fracturing fluid can be used for high-pressure wells and deep wellsThe ultra-deep well and the compact oil-gas reservoir are effectively fractured, the oil-gas productivity is improved, and the pumping pressure of fracturing construction can be obviously reduced, so that the energy consumption of fracturing in the field is reduced;

2. the fracturing fluid has good temperature resistance, so that the fracturing fluid can be used for exploiting oil and gas wells with higher temperature;

3. the fracturing fluid has the characteristic of delayed crosslinking, so that the on-way wear resistance of high-speed pumping of the fracturing fluid can be reduced, the fracturing efficiency is improved, and the energy consumption of fracturing is further reduced;

4. the organic salt weighting agent adopted in the fracturing fluid is non-toxic, harmless and biodegradable, so that the pollution to the environment is greatly reduced;

5. the preparation method of the fracturing fluid is simple and easy to implement, does not need large-scale instruments for assistance, and is suitable for large-scale popularization and application in the field of oil and gas exploitation.

Drawings

FIG. 1 is a flow chart of a method of preparing a fracturing fluid of the present invention;

FIG. 2 is a temperature and shear resistant performance graph of the fracturing fluid of example 1 of the present invention;

FIG. 3 is a temperature and shear resistant performance graph of the fracturing fluid of example 2 of the present invention.

Detailed Description

In order to make the objects, 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 with reference to the embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The invention provides a fracturing fluid which 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 consists of the components, wherein the organic salt weighting agent is a salt consisting of organic acid radical anions and metal cations.

The addition of the organic salt weighting agent can increase the density of the fracturing fluid so as to improve the hydrostatic column pressure of the fracturing fluid, so that the construction pressure of a wellhead can be greatly reduced in the whole construction process, and the problem that the construction pressure of a deep high-temperature reservoir exceeds the construction pressure limit of equipment due to overhigh construction pressure is avoided.

The thickening agent can improve the viscosity of the drilling fluid, reduce the filtration loss rate of the drilling fluid, suspend sand and carry a propping agent.

The cross-linking agent can perform cross-linking reaction with a thickening agent in the fracturing fluid through chemical bonds or coordination bonds, so that a high polymer with a net-shaped structure is generated, and substances with dispersibility can be bound in the high polymer with the net-shaped structure, so that the fracturing pressure can be effectively utilized, and the fracturing effect is enhanced.

The fracturing fluid is mainly used for reservoir fracturing modification of deep wells and high-pressure wells, so that the flowing resistance of the fluid can be reduced by the crosslinking retarder, and the pumping pressure of fracturing construction is further reduced.

The pH adjusting agent is used for adjusting the pH value of the fracturing fluid so as to support the pH value required by the crosslinking reaction of the crosslinking agent.

The bactericide is a chemical additive for preventing and treating the deterioration of the fracturing fluid caused by various pathogenic microorganisms, can prolong the storage time of the fracturing fluid and prevent and treat the propagation of bacteria in the stratum.

The cosolvent can increase the solubility of various components in solvent water, is beneficial to forming a uniform system of the fracturing fluid, is convenient for injecting the fracturing fluid to the bottom of a well, and is also beneficial to the functional balance of various functional components in the fracturing fluid in a stratum.

Breakers aid in the degradation of the fracturing fluid and the flowback out of the fracture to the surface.

The invention limits the types of the raw materials of the fracturing fluid and limits the proportion of the raw materials, thereby having good compatibility of the raw materials and realizing the maximum functionality of the raw materials. It is worth noting that the organic salt weighting agent adopted by the invention can play a certain crosslinking role, so that the proportion of the crosslinking agent in the fracturing fluid is reduced on the premise of not influencing the crosslinking reaction, and the pollution to a reservoir is reduced. In addition, the organic salt weighting agent is non-toxic and harmless, and can carry out biological reduction, thereby further meeting the requirement on environmental protection.

In addition, the fracturing fluid generated according to the proportion also has certain high temperature resistance, and still has good thermal stability and shear stability even under the stratum of 140 ℃, namely, the viscosity of the fracturing fluid is not greatly reduced under high temperature and mechanical shear, so that the crosslinking can be delayed, and the high-temperature reservoir fracturing of deep wells and ultra-deep wells is facilitated.

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 alkali metal elements or alkaline earth metal elements refers to organic acid radicals with the anion number of 1-6 carbon atoms, and the salt with the cation number of alkali metal elements or alkaline earth metal elements.

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

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

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

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

Further, the crosslinking agent is an organoboron 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 alcohol and short-chain aldehyde, wherein the short-chain alcohol and the short-chain aldehyde refer to alcohol or aldehyde with the carbon atom number of 1-4;

further, the gel breaker is ammonium persulfate;

further, the delayed crosslinking 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 density of the fracturing fluid is 1.2-1.4g/cm³The pH value is 10-12, and the fracturing fluid with proper density can be prepared according to the site construction environment and the conditions of a reservoir stratum.

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

s101: adding an organic salt weighting agent, a thickening agent and a cosolvent into water, and stirring to obtain a first solution;

s102: adding a pH regulator into the first solution to obtain a second solution, wherein the pH value of the second solution is 10-12;

s103: adding a temperature stabilizer, a delayed crosslinking agent and a bactericide into the second solution, and stirring to obtain a third solution;

s104: and simultaneously adding a cross-linking agent and a gel breaker into the third solution, and stirring to obtain the fracturing fluid.

In S101, after the organic salt weighting agent is adjusted to the target density, the thickening agent and the cosolvent are sequentially added and stirred for 30-120 min.

It is noted that a series of parameter detection and test can be performed on the fracturing fluid prepared by the method in the laboratory, and in a specific application, the third solution in the step S103 is mixed with the gel breaker, and the mixed solution and the crosslinking agent are pumped into the well bottom through a crosslinking pump simultaneously so that the two are crosslinked at the well bottom to generate the fracturing fluid.

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

The fracturing fluid and the preparation method thereof of the present invention will be described in detail with reference to the following specific examples.