阅读说明：本技术 一种可分相存储高温触发的压裂液及其制备方法和应用 (Fracturing fluid capable of being stored in phase-separable manner and triggered at high temperature, and preparation method and application thereof ) 是由 张康 侯妍 王晨 杨晓武 黄传卿 于 2020-12-15 设计创作，主要内容包括：本发明公开了一种可分相存储高温触发的压裂液及其制备方法和应用,制备方法包括：取白油和复合乳化剂,加热搅拌,制得油相；在搅拌状态下将戊二醛与乙二醇混合,加热20～50℃充分反应,得到羟醛缩合产物；将缩合产物加入到油相中,继续搅拌反应,制得反相乳液；用蒸馏水和聚丙烯酰胺水溶液配制成水相；将反相乳液加入到水相中,搅拌制得分相存储的混合乳液；混合乳液运100～130℃反应,得到压裂液。本发明通过将戊二醛的醛基先行进行保护,与聚丙烯酰胺溶液制成乳液,可实现方便运输的同时避免现场配液,大大缩短了施工周期。(The invention discloses a fracturing fluid capable of being stored in a phase-separable manner and triggered at a high temperature, and a preparation method and application thereof, wherein the preparation method comprises the following steps: heating and stirring white oil and a compound emulsifier to prepare an oil phase; mixing glutaraldehyde and ethylene glycol under a stirring state, heating to 20-50 ℃ for full reaction to obtain an aldol condensation product; adding the condensation product into the oil phase, and continuously stirring for reaction to prepare an inverse emulsion; preparing a water phase by using distilled water and a polyacrylamide aqueous solution; adding the inverse emulsion into the water phase, and stirring to prepare a mixed emulsion with split-phase storage; and carrying out reaction on the mixed emulsion at the temperature of 100-130 ℃ to obtain the fracturing fluid. According to the invention, the aldehyde group of the glutaraldehyde is protected in advance, and the glutaraldehyde and the polyacrylamide solution are prepared into emulsion, so that the field liquid preparation is avoided while the transportation is convenient, and the construction period is greatly shortened.)

1. The fracturing fluid capable of storing high-temperature trigger in a phase-separable manner is characterized by comprising the following main components in structural formula:

wherein the value range of n is 50-1000.

2. The preparation method of the fracturing fluid capable of being stored in a phase-separable manner and triggered at high temperature is characterized by comprising the following steps of:

heating and stirring white oil and a compound emulsifier to prepare an oil phase;

mixing glutaraldehyde and ethylene glycol under stirring, adjusting the pH value to be acidic, and fully reacting to obtain an aldol condensation product;

adding the condensation product into the oil phase, and continuously stirring for reaction to prepare an inverse emulsion;

preparing a water phase by using distilled water and a polyacrylamide aqueous solution; adding the inverse emulsion into the water phase, and stirring to prepare a mixed emulsion with split-phase storage;

and reacting the mixed emulsion at 100-130 ℃ to obtain the fracturing fluid.

3. The preparation method of the fracturing fluid capable of being stored at high temperature in a phase-separable manner according to claim 2, wherein the mass ratio of the white oil to the composite emulsifier is (6-8): 1;

the compound emulsifier is obtained by compounding span 80 and tween 80.

4. The method for preparing the fracturing fluid capable of being stored in a phase-separable manner and triggered at the high temperature according to claim 3, wherein the mass ratio of span 80 to Tween 80 is (2-4): 1.

5. The preparation method of the fracturing fluid capable of being stored in a phase-separable manner and triggered at high temperature is characterized in that the molar ratio of glutaraldehyde to glycol is 1 (4-6).

6. The method for preparing the fracturing fluid capable of being stored in a phase-separable manner and triggered at a high temperature according to claim 2, wherein the pH is adjusted to 2-4.

7. The method for preparing the fracturing fluid capable of being stored in a phase-separable manner and triggered at a high temperature according to claim 2, wherein the glutaraldehyde and the glycol are heated at 20-50 ℃.

8. The method for preparing the fracturing fluid capable of being stored in a phase-separable manner and triggered at high temperature according to claim 2, wherein the concentration of the polyacrylamide aqueous solution is 0.3-0.5 wt%.

9. The method for preparing a phase-separable storage high-temperature triggered fracturing fluid according to claim 2, wherein the volume ratio of the distilled water to the polyacrylamide aqueous solution is 100: 1.

10. The application of the fracturing fluid capable of storing high-temperature triggering in a phase-separable manner in oilfield fracturing is characterized in that,

protecting aldehyde groups of glutaraldehyde, transporting the glutaraldehyde and polyacrylamide mixed emulsion stored in a split-phase manner to a downhole, carrying out self-triggering at 100-130 ℃ and then carrying out reaction, and carrying out fracturing;

the protected formula is as follows:

Technical Field

The invention relates to the technical field of high-temperature well fracturing fluid, in particular to fracturing fluid capable of being stored in a phase-separable manner and triggered at high temperature, and a preparation method and application thereof.

Background

The fracturing fluid systems currently used can be divided into water-based fracturing fluids, oil-based fracturing fluids, foam fracturing fluids, clean fracturing fluids and the like. The water-base fracturing fluid system is widely used at home and abroad, accounts for more than 90 percent, and has a dominant position in fracturing construction, and is prepared by taking water as a solvent or a dispersion medium and adding a thickening agent, a cross-linking agent and an additive in a certain ratio into the water. Wherein the cross-linking agent is one of the main factors determining the viscosity property of the fracturing fluid. The cross-linking agent and the thickening agent generate cross-linking reaction through chemical bonds or coordination bonds, macromolecular chains in the thickening agent are mutually entangled to form a structural net-shaped structure, and the typical viscoelastic gel is further thickened. The cross-linking agent has great influence on the gelling speed, temperature resistance stability and shear stability of a fracturing fluid system and the permeability of a stratum. However, the existing cross-linking agent has no good high-temperature resistance under the high-temperature condition, and the construction operation condition is complex. It is therefore of great interest to develop a fracturing fluid that can be stored in phase separation for ease of transport and self-triggered cross-linking at high temperatures to simplify the manner of operation.

Disclosure of Invention

The invention aims to solve the defects that the existing fracturing fluid is inconvenient to store and the construction operation mode is complex, and provides a fracturing fluid capable of being stored in a phase-separable manner and triggered at high temperature, a preparation method and application thereof, in particular to a fracturing fluid capable of being stored in a phase-separable manner so as to be convenient to transport and self-triggered to be crosslinked at high temperature so as to simplify the operation mode. During transportation, aldehyde groups of glutaraldehyde are protected in the oil phase, and form an emulsion with the polyacrylamide solution. Under the condition of high temperature, the stability of the emulsion is destroyed, and self-triggering occurs to generate crosslinking, thereby greatly simplifying the operation mode.

The technical scheme adopted by the invention is as follows:

the fracturing fluid capable of being stored in a phase-separable manner and triggered at high temperature comprises the following main components in structural formula:

wherein the value range of n is 50-1000.

A preparation method of fracturing fluid capable of being stored in a phase-separable manner and triggered at high temperature comprises the following steps:

heating and stirring white oil and a compound emulsifier to prepare an oil phase;

mixing glutaraldehyde and ethylene glycol under a stirring state, heating to 20-50 ℃ for full reaction to obtain an aldol condensation product;

adding the condensation product into the oil phase, and continuously stirring for reaction to prepare an inverse emulsion;

preparing a water phase by using distilled water and a polyacrylamide aqueous solution; adding the inverse emulsion into the water phase, and stirring to prepare a mixed emulsion with split-phase storage;

and carrying out reaction on the mixed emulsion at the temperature of 100-130 ℃ to obtain the fracturing fluid.

As a further improvement of the invention, the mass ratio of the white oil to the composite emulsifier is (6-8): 1;

the compound emulsifier is obtained by compounding span 80 and tween 80.

As a further improvement of the invention, the mass ratio of span 80 to Tween 80 is (2-4): 1.

As a further improvement of the invention, the molar ratio of the glutaraldehyde to the glycol is 1 (4-6).

As a further improvement of the method, glutaraldehyde and ethylene glycol are heated to 20-50 ℃.

As a further improvement of the method, after being mixed with glycol, glutaraldehyde and ethylene glycol, the pH value is adjusted to 2-4.

As a further improvement of the invention, the concentration of the polyacrylamide aqueous solution is 0.3-0.5 wt%.

As a further improvement of the invention, the volume ratio of the distilled water to the polyacrylamide aqueous solution is 100: 1.

An application of a fracturing fluid capable of storing high-temperature triggering in a phase-separable manner in oilfield fracturing,

protecting aldehyde groups of glutaraldehyde, transporting the glutaraldehyde and polyacrylamide mixed emulsion stored in a split-phase manner to a downhole, carrying out self-triggering at 100-130 ℃ and then carrying out reaction, and carrying out fracturing;

the protected formula is as follows:

compared with the prior art, the invention has the following advantages:

the conventional liquid preparation vehicle for applying polyacrylamide to an oil and gas field needs to enter a field for liquid preparation in advance, a thickening agent is fully swelled in a liquid storage tank, and a fracturing vehicle enters the field and recycles the liquid in the liquid storage tank, so that the problem of nonuniform liquid in the fracturing process is prevented. The construction period is long, the strength of the prepared liquid is high, and the requirement of large-scale fracturing of shale wells cannot be met. According to the invention, the aldehyde group of the glutaraldehyde is protected in advance, and the glutaraldehyde and the polyacrylamide solution are prepared into the emulsion, so that the field liquid preparation is avoided while the glutaraldehyde and the polyacrylamide solution are convenient to transport, the glutaraldehyde and the polyacrylamide solution are directly injected into an oil well, and the emulsion is broken at high temperature along with the rise of the temperature. The water produced by aldol condensation explains the release of glutaraldehyde, which undergoes a crosslinking reaction with polyacrylamide at high temperatures downhole. Can be quickly hydrated and thickened. Greatly shortening the construction period.

Drawings

FIG. 1 is a schematic diagram of a fracturing fluid preparation process;

FIG. 2 is a schematic representation of aldehyde protection;

FIG. 3 is a graph of the salt tolerance of the fracturing fluid prepared in example 3;

fig. 4 is a graph of temperature resistance of the fracturing fluid prepared in example 3.

Detailed Description

The technical solution in the embodiments of the present invention will be clearly and completely described below. It is to be understood that the described embodiments are merely exemplary of the invention, and not restrictive of the full scope of the 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 fracturing fluid capable of being stored in a phase-separable manner and triggered at high temperature comprises the following main components:

wherein the value of n is 50-1000.

The specific preparation process is realized by the following reaction:

specifically, the preparation method of the fracturing fluid capable of being stored in a phase-separable manner and triggered at a high temperature comprises the following steps:

1) heating and stirring white oil and composite emulsifier to obtain oil phase.

The mass ratio of the white oil to the composite emulsifier is (6-8) to 1.

The compound emulsifier is prepared by mixing Span 80(Span-80) and Tween 80 (Tween-80).

The mass ratio of Span-80 to Tween-80 is (2-4) to 1.

The stirring time is 10-20 min.

2) Mixing glutaraldehyde and glycol under stirring, adjusting pH value, and heating for reaction to obtain aldol condensation product.

The molar ratio of the glutaraldehyde to the glycol is 1 (4-6).

The pH value is 2-4.

The reaction temperature is 20-50 ℃.

The reaction time is 5-7 h.

3) Adding the condensation product into the oil phase, and continuously stirring to obtain the inverse emulsion.

4) Preparing water phase with distilled water and polyacrylamide water solution, slowly adding oil phase into the water phase, and stirring to obtain mixed emulsion.

The use concentration of the polyacrylamide solution is 0.3-0.5 wt%.

The volume ratio of distilled water to polyacrylamide in the water phase preparation process is 100: 1.

The stirring time is 10-20 min.

The dropping temperature was room temperature (25 ℃ C.).

5) And transferring the mixed emulsion into a three-neck flask, and stirring in an oil bath at high temperature to obtain the target product.

The oil bath temperature is 100-130 ℃.

The crosslinking agent added in the fracturing fluid is stored in an oil phase, and the protected structural formula is as follows:

the crosslinking of glutaraldehyde with polyacrylamide occurs after high temperature triggering downhole.

The storage of polyacrylamide and glutaraldehyde is phase separated.

The principle is that glutaraldehyde is subjected to an aldol condensation reaction before ethylene glycol to protect aldehyde groups, so that the glutaraldehyde and polyacrylamide can be conveniently stored in a split-phase manner, emulsion breaking is performed at high temperature, a condensation product is subjected to a hydrolysis reaction, and the aldehyde groups are released to be crosslinked with the polyacrylamide.

The invention is further illustrated by the following specific examples and figures:

example 1

160g of white oil is weighed and added into a 500mL beaker, and then 15g of Span-80 and 5g of Tween-80 are added, heated and stirred to prepare an oil phase. Adding 20g of glutaraldehyde and 48g of ethylene glycol under stirring, mixing, adjusting the pH value to 3, and heating and reacting at 25 ℃ for 6 hours to obtain an aldol condensation product. 68g of condensation product are added to 180g of oil phase and stirring is continued for 15min, giving 248g of inverse emulsion. 1mL of 0.5 wt% polyacrylamide solution was added to 100mL of water with stirring, and the prepared mixed emulsion was added thereto and stirred for 15 min. And transferring the mixed emulsion into a three-neck flask, and stirring at 120 ℃ in an oil bath to obtain the target product.

Example 2

160g of white oil is weighed and added into a 500mL beaker, and then 16g of Span-80 and 4g of Tween-80 are added, heated and stirred to prepare an oil phase. Adding 20g of glutaraldehyde and 48g of ethylene glycol under stirring, mixing, adjusting the pH value to 3, and heating and reacting at 25 ℃ for 6 hours to obtain an aldol condensation product. 68g of condensation product are added to 180g of oil phase and stirring is continued for 15min, giving 248g of inverse emulsion. 1mL of 0.4 wt% polyacrylamide solution was added to 100mL of water with stirring, and the prepared mixed emulsion was added thereto and stirred for 15 min. And transferring the mixed emulsion into a three-neck flask, and stirring at 120 ℃ in an oil bath to obtain the target product.

Example 3

160g of white oil is weighed and added into a 500mL beaker, and then 16g of Span-80 and 4g of Tween-80 are added, heated and stirred to prepare an oil phase. Adding 20g of glutaraldehyde and 48g of ethylene glycol under stirring, mixing, adjusting the pH value to 3, and heating and reacting at 25 ℃ for 6 hours to obtain an aldol condensation product. 68g of condensation product are added to 180g of oil phase and stirring is continued for 15min, giving 248g of inverse emulsion. 1mL of 0.5 wt% polyacrylamide solution was added to 100mL of water with stirring, and the prepared mixed emulsion was added thereto and stirred for 15 min. And transferring the mixed emulsion into a three-neck flask, and stirring at 120 ℃ in an oil bath to obtain the target product.

Example 4

160g of white oil is weighed and added into a 500mL beaker, and then 16g of Span-80 and 4g of Tween-80 are added, heated and stirred to prepare an oil phase. Adding 20g of glutaraldehyde and 48g of ethylene glycol under stirring, mixing, adjusting the pH value to 3, and heating and reacting at 25 ℃ for 6 hours to obtain an aldol condensation product. 68g of condensation product are added to 180g of oil phase and stirring is continued for 10min, giving 248g of inverse emulsion. 1mL of 0.4 wt% polyacrylamide solution was added to 100mL of water with stirring, and the prepared mixed emulsion was added thereto and stirred for 15 min. And transferring the mixed emulsion into a three-neck flask, and stirring at 120 ℃ in an oil bath to obtain the target product.

Example 5

160g of white oil is weighed and added into a 500mL beaker, and then 15g of Span-80 and 5g of Tween-80 are added, heated and stirred to prepare an oil phase. Adding 20g of glutaraldehyde and 48g of ethylene glycol under stirring, mixing, adjusting the pH value to 3, and heating and reacting at 25 ℃ for 6 hours to obtain an aldol condensation product. 68g of condensation product are added to 180g of oil phase and stirring is continued for 10min, giving 248g of inverse emulsion. 1mL of 0.3 wt% polyacrylamide solution was added to 100mL of water with stirring, and the prepared mixed emulsion was added thereto and stirred for 20 min. And transferring the mixed emulsion into a three-neck flask, and stirring at 120 ℃ in an oil bath to obtain the target product.

Example 6

160g of white oil is weighed and added into a 500mL beaker, and then 15g of Span-80 and 5g of Tween-80 are added, heated and stirred to prepare an oil phase. Adding 20g of glutaraldehyde and 48g of ethylene glycol under stirring, mixing, adjusting the pH value to 3, and heating and reacting at 25 ℃ for 5 hours to obtain an aldol condensation product. 68g of condensation product are added to 180g of oil phase and stirring is continued for 10min, giving 248g of inverse emulsion. 1mL of 0.4 wt% polyacrylamide solution was added to 100mL of water with stirring, and the prepared mixed emulsion was added thereto and stirred for 15 min. And transferring the mixed emulsion into a three-neck flask, and stirring at 120 ℃ in an oil bath to obtain the target product.

Example 7

1) 160g of white oil is added into a 500mL beaker, and then 16g of Span-80 and 4g of Tween-80 are added, heated and stirred to prepare an oil phase.

2) Adding 20g of glutaraldehyde and 48g of ethylene glycol under stirring, mixing, adjusting the pH value to 3, and heating and reacting at 25 ℃ for 6 hours to obtain an aldol condensation product.

3) 68g of condensation product are added to 180g of oil phase and stirring is continued for 15min, giving 248g of inverse emulsion.

4) 1mL of 0.5 wt% polyacrylamide solution was added to 100mL of water with stirring, and the mixed emulsion prepared in step 3) was added thereto and stirred for 15 min.

5) And transferring the mixed emulsion into a three-neck flask, and stirring at 120 ℃ in an oil bath to obtain the target product.

Characterization and testing:

in order to characterize the salt tolerance of the synthetic fracturing fluid, the fracturing fluid synthesized in example 3 was tested for viscosity at different sodium chloride concentrations, and the results are shown in fig. 2.

As is clear from FIG. 2, the viscosity of the resulting fracturing fluid was still 810 mPas at a sodium chloride concentration of 12 g/L. This shows that the fracturing fluid has good salt resistance.

In order to characterize the high temperature resistance of the synthesized fracturing fluid, the fracturing fluid synthesized in example 3 was subjected to viscosity tests at different temperatures, and the results are shown in fig. 3.

From FIG. 3, it is understood that the viscosity of the resulting fracturing fluid can still reach 195 mPas at a temperature of 100 ℃. This indicates that the fracturing fluid has good tolerance to higher temperatures.

Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art can make modifications and equivalents to the specific embodiments of the present invention without departing from the spirit and scope of the present invention, which is set forth in the following claims.