CN118206973B - In-situ self-generated super-hydrophobic interface layer drag reducer and preparation method thereof - Google Patents

Abstract

The present application relates to the technical field of oilfield chemical reagents, and in particular to an in-situ self-generated super-hydrophobic interface layer drag reducer and a preparation method thereof; the drag reducer comprises, by mass fraction, catalytic emulsifier: 0.5% to 3.0%, nucleating agent: 1.0% to 10%, cross-linking agent: 0.2% to 1.0%, adhesion enhancer: 0.1% to 1.0%, hydrophobic enhancer: 0.1% to 2.0%, activator: 0.3% to 1.0%, and the remainder is water and inevitable impurities; wherein the activator comprises a mixture of urotropine and ammonium chloride; the drag reducer can be injected into the formation in liquid phase, has good injectability and no risk of reservoir damage, and can significantly reduce the water flooding pressure of low-permeability oil reservoirs; at the same time, the drag reducer does not need to be carried by oil phases such as diesel and kerosene, and can use water phase as a carrying liquid, which is low in cost and highly safe and environmentally friendly.

Description

In-situ self-generated super-hydrophobic interface layer drag reducer and preparation method thereof

Technical Field

The present application relates to the technical field of oilfield chemical reagents, and in particular to an in-situ self-generated super-hydrophobic interface layer drag reducer and a preparation method thereof.

Background Art

With the gradual depletion of medium and high permeability oil reservoir resources, low permeability oil reservoir resources have gradually become the main resource type for stable crude oil production; and the exploitation of oil reservoir resources is mainly based on water injection to maintain pressure, but this water injection pressure maintenance technology has poor adaptability, high injection pressure, insufficient water injection volume, and difficulty in replenishing oil reservoir energy in low permeability oil reservoirs. Therefore, it is currently necessary to develop a new exploitation technology suitable for low permeability oil reservoirs. Nano-drag reduction technology injects nanofluids into the formation, and the nanoparticles in the nanofluid can form a hydrophobic layer after being adsorbed on the rock surface. The formation of the hydrophobic layer can reduce the attraction and adhesion of the rock surface to water molecules, thereby greatly reducing the water injection pressure of the reservoir through surface slip, and at the same time can also increase the water injection volume and reservoir energy replenishment effect.

Existing nano drag reduction technologies include: (1) pressure reduction and injection enhancement nano drag reducers, which are mainly composed of hydrophobic nanoparticles, composite surfactants, additives and water. The hydrophobic nanoparticles are hollow silica nanospheres with fluorine-containing groups and long-chain alkyl chains loaded on the surface. The pressure reduction and injection enhancement agent has the advantages of small dosage, good stability, strong timeliness and small adsorption amount, and can effectively reduce the injection pressure of low permeability oil reservoirs; (2) superhydrophobic nano drag reducers, whose preparation process is: under vacuum conditions, nano-silica is dried to remove adsorbed water, and then modified with heptadecafluorodecyltrimethoxysilane to obtain superhydrophobic nanoparticles. The contact angle of water droplets in the air of the superhydrophobic nanoparticles reaches 165°, which can make the superhydrophobic nanoparticles perform well in pressure reduction and injection enhancement of low permeability oil reservoirs, and the drag reduction rate of the superhydrophobic nano drag reducer is more than 1.35 times that of conventional nanomaterials. However, these nano-drag reducers still have some bottleneck problems, which greatly limit the large-scale application of nano-drag reducers in oil reservoirs.

Summary of the invention

The present application provides an in-situ self-generated super-hydrophobic interface layer drag reducer and a preparation method thereof to solve the following problem: how to increase the application scale of nano drag reducers in oil reservoirs.

In a first aspect, the present application provides an in-situ self-generated super-hydrophobic interface layer drag reducer, which comprises, by mass fraction:

Catalytic emulsifier: 0.5%~3.0%, nucleating agent: 1.0%~10%, cross-linking agent: 0.2%~1.0%, adhesion enhancer: 0.1%~1.0%, hydrophobic enhancer: 0.1%~2.0%, activator: 0.3%~1.0%, the balance is water and unavoidable impurities;

Wherein, the activator comprises a mixture of urotropine and ammonium chloride.

Optionally, the mass ratio of the urotropine to the ammonium chloride is 1:1 to 1:2.

Optionally, the catalytic emulsifier includes sodium dodecylbenzene sulfonate and/or sodium petroleum sulfonate.

Optionally, the nucleating agent includes octamethylcyclotetrasiloxane and/or hexamethylcyclotrisiloxane.

Optionally, the crosslinking agent includes ethyl orthosilicate and/or methyl orthosilicate.

Optionally, the adhesion enhancer includes γ-aminopropylmethyldiethoxysilane and/or γ-aminopropyltriethoxysilane.

Optionally, the hydrophobic enhancer includes at least one of the following:

Dodecyltrimethoxysilane, hexadecyltrimethoxysilane, hexadecyltriethoxysilane and octadecylmethyldimethoxysilane.

In a second aspect, the present application provides a method for preparing the drag reducer according to the first aspect, the method comprising:

Mixing the catalytic emulsifier and the activator, and then adding water to the mixture to obtain a mixed aqueous solution;

mixing a nucleating agent, a cross-linking agent, an adhesion enhancer, and a hydrophobic enhancer to obtain a mixed oil;

The mixed oil liquid and the mixed aqueous solution are mixed, and the nucleating agent, the cross-linking agent, the adhesion enhancer, the hydrophobic enhancer and the catalytic emulsifier are subjected to catalytic reaction and emulsification to form an oil-in-water emulsion, and then an in-situ autogenous reaction occurs between the activator to obtain a drag reducer.

Optionally, the mixed oil liquid and the mixed aqueous solution are mixed to cause the nucleating agent, the cross-linking agent, the adhesion enhancer, the hydrophobic enhancer and the catalytic emulsifier to undergo a catalytic reaction and emulsification to form an oil-in-water emulsion, which then undergoes an in-situ autogenous reaction with the activator to obtain a drag reducer, comprising the steps of:

Adding the mixed oil solution dropwise into the mixed aqueous solution and stirring and mixing the mixture, so that the nucleating agent, the crosslinking agent, the adhesion enhancer, the hydrophobic enhancer and the catalytic emulsifier are respectively subjected to catalytic reaction and emulsification to form an oil-in-water emulsion, and then react with the activator in situ to obtain a drag reducer;

Wherein, the rotation speed of the stirring and mixing is 300r/min to 500r/min.

Optionally, the stirring and mixing time is the same as the dripping time of the mixed oil liquid, and the dripping time is 30 minutes to 60 minutes.

The above technical solution provided by the embodiment of the present application has the following advantages compared with the prior art:

An in-situ self-generated super-hydrophobic interface layer drag reducer provided in an embodiment of the present application comprises: a catalytic emulsifier: 0.5% to 3.0%, a nucleating agent: 1.0% to 10%, a cross-linking agent: 0.2% to 1.0%, an adhesion enhancer: 0.1% to 1.0%, a hydrophobic enhancer: 0.1% to 2.0%, an activator: 0.3% to 1.0%, and the remainder is water and unavoidable impurities; the activator may comprise a mixture of urotropine and ammonium chloride, and when the super-hydrophobic interface layer drag reducer enters the underground reservoir in a liquid phase, a stable water-in-oil emulsion is formed between the catalytic emulsifier, the nucleating agent, the cross-linking agent, the adhesion enhancer and the hydrophobic enhancer, and the activator may slowly release an acidic component containing hydrochloric acid, and when the content of the acidic component is sufficient, a sufficient amount of hydrochloric acid may promote the activation of the catalytic emulsifier to produce a cationic catalytic effect, and the activated catalytic emulsifier may cause the nucleating agent to open the ring, and the nucleating agent after the ring opening may shrink with the hydrolyzed cross-linking agent. Polymerization reaction to form solid cross-linked silicone oil nanoparticles, in addition, the hydrophobic enhancer will participate in the condensation reaction after hydrolysis and improve the hydrophobicity of the solid silicone oil nanoparticles, and the adhesion enhancer will participate in the condensation reaction and form a certain number of amine groups on the surface of the solid silicone oil nanoparticles. The amine group can show cationic group characteristics under the water environment and temperature conditions of the underground reservoir, thereby improving the adhesion of the solid silicone oil nanoparticles to the sandstone surface of the underground reservoir. Therefore, through the interaction between the catalytic emulsifier, the nucleating agent, the cross-linking agent, the adhesion enhancer, the hydrophobic enhancer and the activator, solid silicone oil nanoparticles with good adsorption can be generated in situ, and the solid silicone oil nanoparticles can be adsorbed on the rock surface and form a super-hydrophobic interface layer. The super-hydrophobic interface layer can rely on the interface slip effect to greatly reduce the water injection resistance of the low permeability oil reservoir, thereby improving the water injection energy replenishment effect of the low permeability oil reservoir, and then the drag reducer can be used to increase the application scale of nano drag reducers in oil reservoirs.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

FIG1 is a schematic flow chart of a method for preparing an in-situ self-generated super-hydrophobic interface layer drag reducer provided in an embodiment of the present application;

FIG2 is a detailed schematic diagram of a method for preparing an in-situ self-generated super-hydrophobic interface layer drag reducer provided in an embodiment of the present application;

FIG3 is a scanning electron microscope image of solid silicone oil nanoparticles in an in-situ self-generated super-hydrophobic interface layer drag reducer provided in an embodiment of the present application;

FIG. 4 is a schematic diagram of the molding reaction principle of the drag reducer provided in an embodiment of the present application.

DETAILED DESCRIPTION

In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

Unless otherwise specified, various raw materials, reagents, instruments and equipment used in this application can be purchased from the market or prepared by existing methods.

It should be noted that, with respect to the prior art (1) and (2) in the background technology, the inventors have found through a large number of experiments that: (1) the hydrophobic nanoparticles used in the nano-drag reduction technology usually require diesel, kerosene and other oil phases as carrier fluids before they can be injected into underground reservoirs, and the injection of oil phases significantly increases the construction costs and safety risks; (2) the hydrophobic nanoparticles tend to agglomerate when encountering water in underground reservoirs, which can block the pores of the underground reservoirs. Therefore, these bottleneck problems have greatly limited the application scale of nano-drag reducers in oil reservoirs.

The present application embodiment provides an in-situ self-generated super-hydrophobic interface layer drag reducer, which comprises, by mass fraction:

Catalytic emulsifier: 0.5%~3.0%, nucleating agent: 1.0%~10%, cross-linking agent: 0.2%~1.0%, adhesion enhancer: 0.1%~1.0%, hydrophobic enhancer: 0.1%~2.0%, activator: 0.3%~1.0%, the balance is water and unavoidable impurities;

Wherein, the activator comprises a mixture of urotropine and ammonium chloride;

In these embodiments, the mass fraction of the catalytic emulsifier can be 0.5% to 3.0%, which can prompt the catalytic emulsifier to fully promote the ring opening and polymerization of the nucleating agent, thereby conveniently forming solid silicone oil nanoparticles with good adsorption properties through in situ generation. The solid silicone oil nanoparticles can be adsorbed on the rock surface to form a super-hydrophobic interface layer.

The mass fraction of the nucleating agent can be 1.0% to 10%. The ring-opening and polymerization of the nucleating agent can enable the ring-opened nucleating agent to fully copolymerize with the cross-linking agent, adhesion enhancer, and hydrophobic enhancer in the polymerization stage, thereby forming solid silicone oil nanoparticles with good adsorption properties through in-situ generation. The solid silicone oil nanoparticles can be adsorbed on the rock surface and form a sufficient super-hydrophobic interface layer.

The mass fraction of the cross-linking agent can be 0.2% to 1.0%, the mass fraction of the adhesion enhancer can be 0.1% to 1.0%, and the mass fraction of the hydrophobic enhancer can be 0.1% to 2.0%, which can promote the cross-linking agent, the adhesion enhancer and the hydrophobic enhancer to fully copolymerize with the nucleating agent after ring opening in the polymerization stage, thereby improving the water injection energy replenishment effect of the low permeability oil reservoir, and then the drag reducer can be used to increase the application scale of the nano drag reducer in the oil reservoir.

The activator may include a mixture of urotropine and ammonium chloride, which can cause urotropine to slowly release formaldehyde under the action of formation temperature and react with ammonium chloride to generate an acidic component containing hydrochloric acid. This reaction will proceed slowly under normal temperature conditions to ensure that the water-in-oil emulsion can migrate to the deep part of the underground reservoir. When the hydrochloric acid content in the underground reservoir is sufficient, the sufficient amount of hydrochloric acid will produce a cationic catalytic effect together with the catalytic emulsifier, promote the ring-opening polymerization of the nucleating agent and simultaneously undergo a condensation reaction with the hydrolyzed cross-linking agent to generate cross-linked solid silicone oil nanoparticles.

The mass fraction of the activator can be 0.3% to 1.0%, which can cause the activator to slowly release a sufficient amount of acidic components containing hydrochloric acid, and the sufficient amount of acidic components can cause the catalytic emulsifier to activate, and the activated catalytic emulsifier can cause the nucleating agent to open the ring and polymerize. In some optional embodiments, the mass ratio of the hexamine to the ammonium chloride is 1:1 to 1:2;

In these embodiments, the mass ratio of hexamethylenetetramine to ammonium chloride can be 1:1 to 1:2, which can further promote the activator to slowly release a sufficient amount of acidic components containing hydrochloric acid, and the acidic components can further promote the activation of the catalytic emulsifier, so that solid silicone oil nanoparticles with good adsorption can be formed by in-situ generation. The solid silicone oil nanoparticles can be adsorbed on the rock surface of the underground reservoir and form a super-hydrophobic interface layer. The super-hydrophobic interface layer can rely on the interface slip effect to greatly reduce the water injection resistance of the low-permeability oil reservoir, thereby further improving the water injection energy replenishment effect of the low-permeability oil reservoir, and then the drag reducer can be used to effectively increase the application scale of the nano drag reducer in the low-permeability oil reservoir.

The mass ratio of hexamethylenetetramine to ammonium chloride can be 1:1.0, 1:1.1, 1:1.2, 1:1.3, 1:1.4, 1:1.5, 1:1.6, 1:1.7, 1:1.8, 1:1.9 or 1:2.0.

In some optional embodiments, the catalytic emulsifier includes sodium dodecylbenzene sulfonate and/or sodium petroleum sulfonate;

In these embodiments, the catalytic emulsifier may include sodium dodecylbenzene sulfonate and/or sodium petroleum sulfonate, and the catalytic emulsifier may be used to fully promote the ring opening and polymerization of the nucleating agent, thereby conveniently forming a sufficient amount of solid silicone oil nanoparticles through in-situ generation, and a sufficient amount of solid silicone oil nanoparticles may be adsorbed on the rock surface of the underground reservoir to form a super-hydrophobic interface layer, thereby further improving the water injection energy replenishment effect of the low-permeability oil reservoir.

In some optional embodiments, the nucleating agent includes octamethylcyclotetrasiloxane and/or hexamethylcyclotrisiloxane;

In these embodiments, the nucleating agent may include octamethylcyclotetrasiloxane and/or hexamethylcyclotrisiloxane, and the ring-opening and polymerization of the nucleating agent can cause the ring-opened nucleating agent to fully copolymerize with the cross-linking agent, the adhesion enhancer, and the hydrophobic enhancer in the polymerization stage, thereby forming solid silicone oil nanoparticles with good adsorption properties in an in-situ generated manner, and the solid silicone oil nanoparticles can be adsorbed on the rock surface of the underground reservoir and form a sufficient super-hydrophobic interface layer.

In some optional embodiments, the crosslinking agent includes ethyl orthosilicate and/or methyl orthosilicate;

In some optional embodiments, the adhesion enhancer includes γ-aminopropylmethyldiethoxysilane and/or γ-aminopropyltriethoxysilane;

In some optional embodiments, the hydrophobic enhancing agent includes at least one of the following:

dodecyltrimethoxysilane, hexadecyltrimethoxysilane, hexadecyltriethoxysilane, and octadecylmethyldimethoxysilane;

In these embodiments, the cross-linking agent may include ethyl orthosilicate, and the adhesion enhancer may include γ-aminopropylmethyldiethoxysilane and/or γ-aminopropyltriethoxysilane, and the hydrophobic enhancer may include at least one of dodecyltrimethoxysilane, hexadecyltrimethoxysilane, hexadecyltriethoxysilane and octadecylmethyldimethoxysilane, which can promote the cross-linking agent, adhesion enhancer and hydrophobic enhancer to fully copolymerize with the nucleating agent after ring opening in the polymerization stage, thereby improving the water injection energy replenishment effect of low permeability oil reservoirs, and then the drag reducer can be used to increase the application scale of nano drag reducers in oil reservoirs.

FIG4 exemplarily shows a schematic diagram of a molding reaction principle of a drag reducer provided in an embodiment of the present application;

It should be noted that the cross-linking agent ethyl orthosilicate or methyl orthosilicate can be hydrolyzed to produce silicic acid according to the reaction shown in FIG. 4 .

FIG1 exemplarily shows a schematic flow chart of a method for preparing an in-situ self-generated super-hydrophobic interface layer drag reducer provided in an embodiment of the present application;

Based on a general inventive concept, as shown in FIG1 , the present embodiment provides a method for preparing the drag reducer, the method comprising:

S1. The catalytic emulsifier and the activator are mixed, and water is added to the mixture to obtain a mixed aqueous solution;

S2. mixing the nucleating agent, the cross-linking agent, the adhesion enhancer and the hydrophobic enhancer to obtain a mixed oil;

S3. The mixed oil liquid and the mixed aqueous solution are mixed, so that the nucleating agent, the cross-linking agent, the adhesion enhancer, the hydrophobic enhancer and the catalytic emulsifier react and emulsify to form an oil-in-water emulsion, and then an in-situ autogenous reaction occurs between the emulsion and the activator to obtain a drag reducer.

This method is a method for preparing the above-mentioned drag reducer. The specific composition of the drag reducer can refer to the above-mentioned embodiment. Since this method adopts part or all of the technical solutions of the above-mentioned embodiment, it at least has all the beneficial effects brought by the technical solutions of the above-mentioned embodiment, which will not be repeated here one by one.

FIG2 exemplarily shows a detailed schematic diagram of a method for preparing an in-situ self-generated super-hydrophobic interface layer drag reducer provided in an embodiment of the present application;

As shown in FIG2 , in some optional embodiments, the mixed oil and the mixed aqueous solution are mixed, and the nucleating agent, the cross-linking agent, the adhesion enhancer, the hydrophobic enhancer and the catalytic emulsifier are subjected to catalytic reaction and emulsification to form an oil-in-water emulsion, and then an in-situ autogenous reaction occurs between the activator to obtain a drag reducer, comprising the steps of:

S301. dropping the mixed oil into the mixed aqueous solution and stirring and mixing, so that the nucleating agent, the cross-linking agent, the adhesion enhancer, the hydrophobic enhancer and the catalytic emulsifier are respectively subjected to catalytic reaction and emulsification to form an oil-in-water emulsion, and then react with the activator in situ to obtain a drag reducer;

Wherein, the rotation speed of the stirring and mixing is 300r/min～500r/min;

In these embodiments, the stirring and mixing speed can be 300r/min to 500r/min, which can promote the formation of a stable water-in-oil emulsion between the catalytic emulsifier, the nucleating agent, the cross-linking agent, the adhesion enhancer and the hydrophobic enhancer. In addition, through the interaction between the catalytic emulsifier, the nucleating agent, the cross-linking agent, the adhesion enhancer, the hydrophobic enhancer and the activator, solid silicone oil nanoparticles with good adsorption can be formed by in situ generation. The solid nanoparticles can be adsorbed on the rock surface of the underground reservoir and form a super-hydrophobic interface layer. The super-hydrophobic interface layer can rely on the interface slip effect to greatly reduce the water injection resistance of the low-permeability oil reservoir, thereby improving the water injection energy replenishment effect of the low-permeability oil reservoir, and then the drag reducer can be used to increase the application scale of nano drag reducers in oil reservoirs.

The rotation speed of the stirring and mixing can be 300r/min, 350r/min, 400r/min, 450r/min or 500r/min.

In some embodiments, the stirring and mixing time is the same as the dropwise addition time of the mixed oil liquid, and the dropwise addition time is 30 min to 60 min;

In these embodiments, the stirring and mixing time can be the same as the mixed oil droplet addition time, and the droplet addition time can be 30 minutes to 60 minutes. The mixed oil and the mixed aqueous solution can be fully reacted by slow droplet addition, so that solid-phase nanoparticles with good adsorption can be formed by in-situ generation. The solid-phase nanoparticles can be adsorbed on the rock surface and form a super-hydrophobic interface layer. The super-hydrophobic interface layer can rely on the interface slip effect to greatly reduce the water injection resistance of the low-permeability oil reservoir, thereby improving the water injection energy replenishment effect of the low-permeability oil reservoir, and then the drag reducer can be used to increase the application scale of the nano drag reducer in the oil reservoir.

The dropping time may be 30 min, 35 min, 40 min, 45 min, 50 min, 55 min or 60 min.

It should be noted that after the dropwise addition is completed, stirring needs to be continued for a period of time to ensure that all materials are mixed completely.

The present application will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are intended only to illustrate the present application and are not intended to limit the scope of the present application. The experimental methods for which specific conditions are not specified in the following examples are usually measured according to industry standards. If there is no corresponding industry standard, then the conditions recommended by the manufacturer are followed.

Example 1

An in-situ self-generated super-hydrophobic interface layer drag reducer, measured by mass fraction, 100g of the drag reducer comprises:

Catalytic emulsifier: 0.5%, nucleating agent: 1.0%, cross-linking agent: 0.2%, adhesion enhancer: 0.1%, hydrophobic enhancer: 0.1%, activator: 0.3%, the balance is water and unavoidable impurities;

Wherein, the activator is a mixture of urotropine and ammonium chloride.

The mass ratio of hexamethylenetetramine to ammonium chloride is 1:1.

The catalytic emulsifier is sodium dodecylbenzene sulfonate.

The nucleating agent is octamethylcyclotetrasiloxane.

The crosslinking agent is tetraethyl orthosilicate.

The adhesion enhancer is γ-aminopropylmethyldiethoxysilane.

The hydrophobic enhancer is octadecylmethyldimethoxysilane.

As shown in FIG2 , a method for preparing the drag reducer comprises:

S1. The catalytic emulsifier and the activator are mixed, and water is added to the mixture to obtain a mixed aqueous solution;

S2. mixing the nucleating agent, the cross-linking agent, the adhesion enhancer and the hydrophobic enhancer to obtain a mixed oil;

S301. Adding the mixed oil liquid dropwise to the mixed aqueous solution and stirring and mixing, so that the nucleating agent, the cross-linking agent, the adhesion enhancer, the hydrophobic enhancer, the catalytic emulsifier and the activator undergo an in-situ spontaneous reaction and generate a super-hydrophobic interface layer to obtain a drag reducer;

The stirring and mixing speed is 400 r/min.

The stirring and mixing time is the same as the dropwise addition time of the mixed oil, which is 60 minutes.

Example 2

Based on the content disclosed in Example 1, the following modifications are further made:

In terms of mass fraction, 100g of drag reducer includes:

Catalytic emulsifier: 3.0%, nucleating agent: 10%, cross-linking agent: 1.0%, adhesion enhancer: 1.0%, hydrophobic enhancer: 2.0%, activator: 1.0%, the balance is water and unavoidable impurities;

Wherein, the activator is a mixture of urotropine and ammonium chloride.

The mass ratio of hexamethylenetetramine to ammonium chloride is 1:1.

The catalytic emulsifier is sodium dodecylbenzene sulfonate.

The nucleating agent is octamethylcyclotetrasiloxane.

The crosslinking agent is tetraethyl orthosilicate.

The adhesion enhancer is γ-aminopropylmethyldiethoxysilane.

The hydrophobic enhancer is dodecyltrimethoxysilane.

Example 3

Based on the content disclosed in Example 1, the following modifications are further made:

In terms of mass fraction, 100g of drag reducer includes:

Catalytic emulsifier: 1.5%, nucleating agent: 4%, cross-linking agent: 0.5%, adhesion enhancer: 0.3%, hydrophobic enhancer: 0.4%, activator: 0.6%, the balance is water and unavoidable impurities;

Wherein, the activator comprises a mixture of urotropine and ammonium chloride.

The mass ratio of hexamethylenetetramine to ammonium chloride is 1:2.

The catalytic emulsifier is sodium petroleum sulfonate.

The nucleating agent is octamethylcyclotetrasiloxane.

The crosslinking agent is tetraethyl orthosilicate.

The adhesion enhancer is γ-aminopropyltriethoxysilane.

The hydrophobic enhancer is hexadecyltrimethoxysilane.

Example 4

Based on the content disclosed in Example 1, the following modifications are further made:

In terms of mass fraction, 100g of drag reducer includes:

Catalytic emulsifier: 2.0%, nucleating agent: 6.0%, cross-linking agent: 0.4%, adhesion enhancer: 0.5%, hydrophobic enhancer: 0.2%, activator: 0.6%, the balance is water and unavoidable impurities;

Wherein, the activator is a mixture of urotropine and ammonium chloride.

The mass ratio of hexamethylenetetramine to ammonium chloride is 1:1.

The catalytic emulsifier is sodium dodecylbenzene sulfonate.

The nucleating agent is octamethylcyclotetrasiloxane.

The crosslinking agent is tetraethyl orthosilicate.

The adhesion enhancer is γ-aminopropyltriethoxysilane.

The hydrophobic enhancer is hexadecyltriethoxysilane.

Comparative Example 1

Based on the content disclosed in Example 1, the following modifications are further made:

A conventional nano drag reducer was used, the components of which were calculated by mass fraction as follows: hydrophobic nano silica: 0.1%, dispersant Tween 80: 0.5%, and the rest being water.

Comparative Example 2

Based on the content disclosed in Example 1, the following modifications are further made:

In terms of mass fraction, 100g of drag reducer includes:

Catalytic emulsifier: 3.0%, nucleating agent: 10.0%, cross-linking agent: 1.0%, adhesion enhancer: 1.0%, hydrophobic enhancer: 2.0%, the balance is water and unavoidable impurities;

Wherein, the activator is a mixture of urotropine and ammonium chloride.

The mass ratio of hexamethylenetetramine to ammonium chloride is 1:1.

The catalytic emulsifier is sodium dodecylbenzene sulfonate.

The nucleating agent is octamethylcyclotetrasiloxane.

The crosslinking agent is tetraethyl orthosilicate.

The adhesion enhancer is γ-aminopropylmethyldiethoxysilane.

The hydrophobic enhancer is dodecyltrimethoxysilane.

Comparative Example 3

Based on the content disclosed in Example 1, the following modifications are further made:

In terms of mass fraction, 100g of drag reducer includes:

Catalytic emulsifier: 3.0%, nucleating agent: 10.0%, cross-linking agent: 1.0%, hydrophobic enhancer: 2.0%, activator: 1.0%, the balance is water and unavoidable impurities;

Wherein, the activator is a mixture of urotropine and ammonium chloride.

The mass ratio of hexamethylenetetramine to ammonium chloride is 1:1.

The catalytic emulsifier is sodium dodecylbenzene sulfonate.

The nucleating agent is octamethylcyclotetrasiloxane.

The crosslinking agent is tetraethyl orthosilicate.

The hydrophobic enhancer is dodecyltrimethoxysilane.

Comparative Example 4

Based on the content disclosed in Example 1, the following modifications are further made:

In terms of mass fraction, 100g of drag reducer includes:

Catalytic emulsifier: 3.0%, nucleating agent: 10.0%, cross-linking agent: 1.0%, adhesion enhancer: 1.0%, activator: 1.0%, the balance is water and unavoidable impurities;

Wherein, the activator is a mixture of urotropine and ammonium chloride.

The mass ratio of hexamethylenetetramine to ammonium chloride is 1:1.

The catalytic emulsifier is sodium dodecylbenzene sulfonate.

The nucleating agent is octamethylcyclotetrasiloxane.

The crosslinking agent is tetraethyl orthosilicate.

The adhesion enhancer is γ-aminopropylmethyldiethoxysilane.

The hydrophobic enhancer is dodecyltrimethoxysilane.

Comparative Example 5

Based on the content disclosed in Example 1, the following modifications are further made:

In terms of mass fraction, 100g of drag reducer includes:

Catalytic emulsifier: 0.5%, nucleating agent: 1.0%, cross-linking agent: 0.2%, adhesion enhancer: 0.1%, hydrophobic enhancer: 0.1%, activator: 2.0%, the balance is water and unavoidable impurities;

Wherein, the activator is a mixture of urotropine and ammonium chloride.

The mass ratio of hexamethylenetetramine to ammonium chloride is 1:1.

The catalytic emulsifier is sodium dodecylbenzene sulfonate.

The nucleating agent is octamethylcyclotetrasiloxane.

The crosslinking agent is tetraethyl orthosilicate.

The adhesion enhancer is γ-aminopropylmethyldiethoxysilane.

The hydrophobic enhancer is octadecylmethyldimethoxysilane.

Comparative Example 6

Based on the content disclosed in Example 1, the following modifications are further made:

In terms of mass fraction, 100g of drag reducer includes:

Catalytic emulsifier: 0.5%, nucleating agent: 1.0%, cross-linking agent: 0.2%, adhesion enhancer: 2.0%, hydrophobic enhancer: 0.1%, activator: 0.3%, the balance is water and unavoidable impurities;

Wherein, the activator is a mixture of urotropine and ammonium chloride.

The mass ratio of hexamethylenetetramine to ammonium chloride is 1:1.

The catalytic emulsifier is sodium dodecylbenzene sulfonate.

The nucleating agent is octamethylcyclotetrasiloxane.

The crosslinking agent is tetraethyl orthosilicate.

The adhesion enhancer is γ-aminopropylmethyldiethoxysilane.

The hydrophobic enhancer is octadecylmethyldimethoxysilane.

Comparative Example 7

Based on the content disclosed in Example 1, the following modifications are further made:

In terms of mass fraction, 100g of drag reducer includes:

Catalytic emulsifier: 0.5%, nucleating agent: 1.0%, cross-linking agent: 0.2%, adhesion enhancer: 0.1%, hydrophobic enhancer: 3.0%, activator: 0.3%, the balance is water and unavoidable impurities;

Wherein, the activator is a mixture of urotropine and ammonium chloride.

The mass ratio of hexamethylenetetramine to ammonium chloride is 1:1.

The catalytic emulsifier is sodium dodecylbenzene sulfonate.

The nucleating agent is octamethylcyclotetrasiloxane.

The crosslinking agent is tetraethyl orthosilicate.

The adhesion enhancer is γ-aminopropylmethyldiethoxysilane.

The hydrophobic enhancer is octadecylmethyldimethoxysilane.

Related experiments and effect data:

1. Use sandstone core slices to test the influence of different samples on the wettability of the core slice surface, and use the Kruss contact angle meter (DSA) to measure the contact angle of water droplets on the surface of the core slice. The specific steps are as follows:

The drag reducers obtained in Examples 1 to 4 and Comparative Examples 1 to 6 were respectively immersed in sandstone core pieces at 70 ^° C for 15 days, then the sandstone core pieces were taken out and dried in a constant temperature drying oven at 40 ^° C, and then the water drop contact angle test was performed. The results are shown in Table 1.

Table 1 Data of oil drop contact angles on the surface of sandstone core pieces soaked in drag reducers obtained in various examples and comparative examples

As can be seen from Table 1, the water drop contact angle of the blank group is 21.6 ^° , indicating that the surface of the sandstone core piece used is hydrophilic. After being soaked in different drag reducers, the water drop contact angle on the surface of the sandstone core piece changes. The water drop contact angle corresponding to the drag reducer of each embodiment is greater than 150 ^° , which indicates that the sandstone core soaked in the drag reducer of the embodiment forms a superhydrophobic surface.

In addition, the water drop contact angles corresponding to the drag reducers of Comparative Examples 1, 2, 3, 4 and 7 are 131.6 ^° , 56.2 ^° , 133.4 ^° , 116.7 ^° and 102.8 ^° , respectively, and these water drop contact angles are all less than 150 ^° , indicating that the surface of the sandstone core piece is not in a superhydrophobic state at this time, while the water drop contact angles corresponding to the drag reducers of Comparative Examples 5 and 6 are 150.4 ^° and 153.7 ^° , respectively, indicating that the surface of the core piece reaches a superhydrophobic state.

In addition, the drag reducer obtained in Comparative Example 1 is a conventional nano-polysilicon drag reducer, which is mainly composed of hydrophobic nano-silica and dispersant TWEEN80. Affected by the adsorption of dispersant TWEEN80, there is a small amount of TWEEN80 hydrophilic head group on the core surface, and the core surface cannot reach a super-hydrophobic state; compared with Example 1, the drag reducer of Comparative Example 5 contains an excessive amount of activator, which will shorten the time for the solid phase particles of the drag reducer to be generated in situ, but will not affect the performance of the drag reducer particles, so the core surface still reaches a super-hydrophobic state; compared with Example 1, the drag reducer of Comparative Example 6 contains an excessive amount of adhesion enhancer, which will increase the adsorption amount of the solid particles generated in situ by the drag reducer on the core surface, so the core surface still reaches a super-hydrophobic state; compared with Example 1, Comparative Example 7 contains an excessive amount of hydrophobic enhancer, and the solid particles generated in situ by the drag reducer are too hydrophobic, difficult to be stably dispersed in water, and some particles are suspended on the water surface after formation, and cannot be effectively adsorbed on the rock surface, so the core surface can only reach a weakly hydrophobic state.

Compared with Example 1, the drag reducer of Comparative Example 3 does not add an adhesion enhancer, and the adsorption density of the drag reducer without an adhesion enhancer component on the surface of the sandstone core is relatively low. In addition, the roughness of the adsorption layer formed by the drag reducer of Comparative Example 3 is relatively small, and a super-hydrophobic state cannot be formed on the surface of the sandstone core. Based on the same principle, compared with Example 2, no hydrophobic enhancer is added to the drag reducer of Comparative Example 4, and the drag reducer without a hydrophobic enhancer can only form a hydrophobic interface on the surface of the sandstone core, thereby failing to cause the drag reducer to reach a super-hydrophobic state. Compared with Example 2, no activator is added to the drag reducer of Comparative Example 2, which prevents the other components of the drag reducer from being transformed from a liquid phase into solid-phase nanoparticles. In addition, the drag reducer of Comparative Example 2 can only slightly improve the surface hydrophobicity of the sandstone core, but the surface of the sandstone core is still in a hydrophilic state, and the slightly improved surface hydrophobicity of the sandstone core may be related to the spreading of the oil phase component in the drag reducer on the surface of the sandstone core.

2. Evaluation of pressure reduction and injection performance:

The core displacement experiment was used to measure the pressure reduction and injection performance of different drag reducers. The cores used in the test were all artificial cores (φ2.5cm×10cm, porosity of 10%, permeability of 0.4mD). The displacement rate was always maintained at 0.05mL/min during the test process. The temperature during the experiment was 70 ^o C. If the water drive was stable until the pressure was stable, the stable pressure was recorded as P1; the drag reducers of the embodiment and the comparative example were used to drive 1PV respectively, and then stood for 72h, and then subsequent water drive was carried out until the pressure was stable, and the stable pressure was recorded as P2. The drag reduction performance of the drag reducer was quantitatively evaluated by the drag reduction rate E. The calculation formula of the drag reduction rate E is:

E=[(P1-P2)/P1]*100%.

The drag reduction rates of different drag reducers are shown in Table 2.

Table 2 Drag reduction rate of different drag reducers

As can be seen from Table 2, the pressure reduction rate of the drag reducer of each embodiment reached more than 44%, which shows that the drag reducer of the embodiment of the present application can form a super-hydrophobic interface on the surface of the sandstone core, and the formed super-hydrophobic interface has a significant slip effect, thereby reducing the seepage resistance of the water phase, and the subsequent water drive pressure is greatly reduced compared with the water drive; the drag reducers of Comparative Examples 1, 2, 3, and 4 cannot form a super-hydrophobic state on the rock surface, and can only reach a general hydrophobic state or still a hydrophilic state, so the maximum drag reduction rate is only 31.6%; the drag reducer of Comparative Example 5 has an excessively high amount of activator, and the in-situ self-generated solid phase nanostructured ... The rice particles were formed too early, and a large number of solid nanoparticles were formed before the injection was completed, which caused the blockage of some pores in the core and resulted in a negative blocking rate; the drag reducer in Comparative Example 6 contained excessive adhesion enhancer. Although it could convert the core surface into a superhydrophobic state, the adsorption amount at the core injection end was too high, resulting in insufficient adsorption at the middle and rear ends of the core. Therefore, the drag reduction rate was relatively low at 19.3%; the drag reducer in Comparative Example 7 had too high an amount of hydrophobic enhancer. Excessive hydrophobic groups weakened the electrostatic attraction between the cations on the adsorption enhancer and the rock surface of the underground reservoir. The adsorption amount in the core was insufficient, and the drag reduction rate was only 8.8%.

In summary, the embodiment of the present application provides an in-situ self-generated super-hydrophobic interface layer drag reducer, which can be injected into the formation in liquid phase, has good injectability and no risk of reservoir damage. In addition, as shown in Figure 3, the drag reducer has good deep migration performance, and can generate solid silicone oil nanoparticles in situ in the water phase environment of the formation. The solid silicone oil nanoparticles can spontaneously form a super-hydrophobic interface layer on the rock surface to increase the drag reduction efficiency of the drag reducer to more than 44%. Therefore, the drag reducer can significantly reduce the water drive pressure of low-permeability oil reservoirs. At the same time, the drag reducer does not need to be carried by oil phases such as diesel and kerosene, and can use the water phase as a carrying liquid, which is low in cost and highly safe and environmentally friendly.

Various embodiments of the present application may be presented in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity, and should not be understood as a rigid limitation on the scope of the present application; therefore, the range description should be considered to have specifically disclosed all possible sub-ranges and single numerical values within the range. For example, the range description from 1 to 6 should be considered to have specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single numbers within the range, such as 1, 2, 3, 4, 5 and 6, which apply regardless of the range. In addition, whenever a numerical range is indicated herein, it is meant to include any cited number (fractional or integer) within the indicated range.

In the description of the specification of this application, the terms "include", "comprise", etc. mean "including but not limited to". In this article, "and/or" describes the association relationship of associated objects, indicating that three relationships may exist. For example, A and/or B can represent: A exists alone, A and B exist at the same time, and B exists alone. Wherein A and B can be singular or plural. In this article, "at least one" means one or more, and "plural" means two or more. "At least one", "at least one of the following" or similar expressions refer to any combination of these items, including any combination of single items or plural items. For example, "at least one of a, b, or c", or "at least one of a, b, and c" can all represent: a, b, c, a-b (i.e., a and b), a-c, b-c, or a-b-c, where a, b, c can be single or multiple.

The above description is only a specific implementation of the present application, so that those skilled in the art can understand or implement the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest range consistent with the principles and novel features applied for herein.

Claims (5)

1. An in situ self-generating superhydrophobic interfacial layer drag reducer, comprising, in mass fraction:

Catalytic emulsifier: 0.5 to 3.0 percent of nucleating agent: 1.0 to 10 percent of cross-linking agent: 0.2 to 1.0 percent of adhesion reinforcing agent: 0.1 to 1.0 percent of hydrophobic reinforcing agent: 0.1 to 2.0 percent of activator: 0.3 to 1.0 percent, and the balance of water and unavoidable impurities;

Wherein the activator comprises a mixture of urotropine and ammonium chloride;

The catalytic emulsifier comprises sodium dodecyl benzene sulfonate and/or sodium petroleum sulfonate;

the nucleating agent comprises octamethyl cyclotetrasiloxane and/or hexamethylcyclotrisiloxane;

The cross-linking agent comprises ethyl orthosilicate and/or methyl orthosilicate;

the adhesion enhancer comprises gamma-aminopropyl methyl diethoxy silane and/or gamma-aminopropyl triethoxy silane;

the hydrophobic enhancer comprises at least one of the following:

dodecyl trimethoxy silane, cetyl triethoxy silane and stearyl methyl dimethoxy silane.

2. The drag reducer of claim 1, wherein the mass ratio of urotropin to ammonium chloride is 1:1-1:2.

3. A method of preparing the drag reducer of claim 1 or 2, said method comprising:

Mixing a catalytic emulsifier and an activator, and then adding water into the mixture to obtain a mixed aqueous solution;

Mixing a nucleating agent, a cross-linking agent, an adhesion enhancer and a hydrophobic enhancer to obtain mixed oil;

And mixing the mixed oil liquid and the mixed aqueous solution to enable the nucleating agent, the cross-linking agent, the adhesion enhancer, the hydrophobic enhancement and the catalytic emulsifier to perform catalytic reaction and emulsion to form an oil-in-water emulsion, and then to perform in-situ autogenous reaction with the activating agent to obtain the drag reducer.

4. A method according to claim 3, wherein said mixing said mixed oil and said mixed aqueous solution results in an in situ autogenous reaction between said nucleating agent, said cross-linking agent, said adhesion enhancing agent, said hydrophobic enhancing agent and said catalytic emulsifier after catalytic reaction and emulsification to form an oil-in-water emulsion and said activating agent to yield a drag reducing agent, comprising the steps of:

Dropwise adding the mixed oil liquid into the mixed aqueous solution, stirring and mixing the mixed oil liquid to enable the nucleating agent, the cross-linking agent, the adhesion enhancer, the hydrophobic enhancement and the catalytic emulsifier to respectively perform catalytic reaction and emulsification to form oil-in-water emulsion, and then performing in-situ autogenous reaction with the activating agent to obtain a drag reducer;

Wherein the rotation speed of stirring and mixing is 300 r/min-500 r/min.

5. The method according to claim 4, wherein the stirring and mixing time is the same as the mixed oil dripping time, and the dripping time is 30-60 min.