1. The combined catalytic viscosity reducer is characterized by consisting of four slugs, wherein the four slugs are a catalyst slug, a heat generating agent slug, a gas injection slug and a water-soluble viscosity reducer slug;

the catalyst slug comprises the following components in percentage by mass: 10-15% of azacarbene iron, 15-30% of tert-butyl hydroperoxide, 2-5% of phosphoric acid, 2-5% of hydrogen donor, 0.5-1% of emulsifier and the balance of solvent, wherein the total amount is 100%;

the heat generating agent comprises NaNO according to mass percentage₂10-30％，NH₄Cl 8-25%, acid initiator 3-10%, and water in balance, the total amount being 100%;

the water-soluble viscosity reducer comprises, by mass, 0.2-0.5% of a surfactant, 2-10% of an alkali and the balance of water, wherein the total amount is 100%.

2. The combined catalytic viscosity reducer of claim 1, wherein the catalyst is prepared by the following steps: dissolving the azacarbene iron and the tert-butyl hydroperoxide in a solvent, and then adding phosphoric acid, a hydrogen donor and an emulsifier for mixing to obtain the compound.

3. The combined catalytic viscosity reducer of claim 1, wherein the gas injected into the gas injection slug is nitrogen or carbon dioxide.

4. The combined catalytic viscosity reducer of claim 1, wherein the solvent is one or more of benzene, toluene, xylene, kerosene, and diesel; and/or the hydrogen donor is one or more of methanol, ethanol, tetrahydronaphthalene, formic acid, formamide and glycerol; and/or the emulsifier is one or two of span 60 and span 80.

5. The combination catalytic viscosity reducer of claim 1, wherein the acid initiator is one or more of phosphoric acid, hydrochloric acid, sulfuric acid, and acetic acid.

6. The combined catalytic viscosity reducer of claim 1, wherein the surfactant is alkylphenol ethoxylates.

7. Use of the combined catalytic viscosity reducer of any one of claims 1-6 in the degradation of heavy oil.

8. Use according to claim 7, characterized in that it comprises the following steps:

s1, adding a catalyst and water into the thickened oil, wherein the dosage of the catalyst is 0.5-2% of the mass of the thickened oil;

s2, continuously adding a heat generating agent into the thick oil at the temperature of 50-60 ℃;

s3, continuing to inject gas into the thickened oil until the pressure reaches 4-6MPa, and then adding a water-soluble viscosity reducer for viscosity reduction.

9. The use according to claim 8, characterized in that in step S1, water is added to the thick oil in a mass ratio of water to the thick oil (3-4) to (6-7).

10. The use of claim 8, wherein in step S2, adding the heat generating agent comprises: firstly, NaNO is added₂And NH₄Cl was dissolved in water and added to the thick oil followed by the addition of the acid initiator.

Background

China has large thick oil reserves and high development difficulty. At present, the oil field generally adopts a physical method, and the viscosity of the thickened oil is reduced by means of heat, sound waves, magnetic force or thin oil drive and other methods, so that the capability of transporting the crude oil to a production well is improved. However, the above-mentioned processes generally require high energy consumption and enormous water consumption. In recent years, chemical viscosity reduction technology has been increasingly gaining attention in the development of heavy oil reservoirs. The mobility of thick oils can be significantly improved by the addition of surfactants or bases to form water/oil or oil/water emulsions, but for thick oils of high viscosity in the formation, the capacity is still limited. The viscosity of heavy crude oil can be irreversibly reduced under the assistance of high-temperature steam by adding a water thermal cracking catalyst, but the temperature required by the catalytic reaction of underground water thermal cracking is high, the range of the temperature reached by a stratum under the conventional steam injection condition is small, so that the action range of the catalyst is limited, and particularly, the heat loss is large in the process of injecting steam into the stratum in a well with large burial depth, so that the temperature required by hydrothermal cracking is difficult to reach; meanwhile, the mobility and the dispersibility of the catalyst in the thickened oil are relatively poor, and the catalyst is also an important factor influencing the catalysis viscosity reduction effect.

How to improve the viscosity reduction efficiency of the thickened oil under the condition of avoiding injecting steam is a technical problem which needs to be solved urgently in the prior art.

Disclosure of Invention

The invention aims to overcome the technical defects, provides a combined catalytic viscosity reducer and application thereof, and solves the technical problem of improving the viscosity reducing efficiency of thickened oil under the condition of avoiding steam injection in the prior art.

In order to achieve the technical purpose, the technical scheme of the invention provides a combined catalytic viscosity reducer and application thereof.

The invention provides a combined catalytic viscosity reducer, which consists of four slugs, wherein the four slugs are a catalyst slug, a heat generating agent slug, a gas injection slug and a water-soluble viscosity reducer slug;

the catalyst slug comprises the following components in percentage by mass: 10-15% of azacarbene iron, 15-30% of tert-butyl hydroperoxide, 2-5% of phosphoric acid, 2-5% of hydrogen donor, 0.5-1% of emulsifier and the balance of solvent, wherein the total amount is 100%;

the heat generating agent comprises NaNO according to mass percentage₂10-30％，NH₄Cl 8-25%, acid initiator 3-10%, and water in balance, the total amount being 100%;

the water-soluble viscosity reducer comprises, by mass, 0.2-0.5% of a surfactant, 2-10% of an alkali and the balance of water, wherein the total amount is 100%.

Further, the catalyst is prepared according to the following steps: dissolving the azacarbene iron and the tert-butyl hydroperoxide in a solvent, and then adding phosphoric acid, a hydrogen donor and an emulsifier for mixing to obtain the compound.

Further, the gas injected into the gas injection slug is nitrogen or carbon dioxide.

Further, the solvent is one or more of benzene, toluene, xylene, kerosene and diesel oil; and/or the hydrogen donor is one or more of methanol, ethanol, tetrahydronaphthalene, formic acid, formamide and glycerol; and/or the emulsifier is one or two of span 60 and span 80.

Further, the acid initiator is one or more of phosphoric acid, hydrochloric acid, sulfuric acid and acetic acid.

Further, the surfactant is alkylphenol polyoxyethylene.

The invention also provides an application of the combined catalytic viscosity reducer in the degradation of thick oil.

Further, the application comprises the steps of:

s1, adding a catalyst and water into the thickened oil, wherein the dosage of the catalyst is 0.5-2% of the mass of the thickened oil;

s2, continuously adding a heat generating agent into the thick oil at the temperature of 50-60 ℃;

s3, continuing to inject gas into the thickened oil until the pressure reaches 4-6MPa, and then adding a water-soluble viscosity reducer for viscosity reduction.

Further, in step S1, water is added into the thick oil according to the mass ratio of the water to the thick oil (3-4) to (6-7).

Further, in step S2, adding the heat generating agent includes: firstly, NaNO is added₂And NH₄Cl was dissolved in water and added to the thick oil followed by the addition of the acid initiator.

Compared with the prior art, the invention has the beneficial effects that: the combined catalytic viscosity reducer provided by the invention consists of four slugs, wherein the four slugs are a catalyst slug, a heat generating agent slug and a gas injection slug water-soluble viscosity reducer slug; when the thickened oil is degraded, the four slugs are sequentially injected, the heat generating agent provides proper temperature for catalytic degradation, the pressure of a reaction system can be adjusted to 4-6MPa by the gas injection slug, the azacyclo-carbene iron in the catalyst slug can effectively promote the water-soluble viscosity reducer to reduce the viscosity of the thickened oil under the assistance of other components, the thickened oil is treated for 12 hours, and the viscosity reduction rate can reach 96.5%.

Drawings

FIG. 1 is a NMR chart of chemical structure identification of an azacarbene in accordance with embodiments of the present invention.

Detailed Description

The specific embodiment provides a combined catalytic viscosity reducer, which consists of four slugs, wherein the four slugs are a catalyst slug, a heat generating agent slug, a gas injection slug and a water-soluble viscosity reducer slug; the gas injection is used for promoting the mixing of the thickened oil and improving the viscosity reduction efficiency;

the catalyst slug comprises the following components in percentage by mass: 10-15% of azacyclo-ferric carbine, 15-30% of tert-butyl hydroperoxide, 2-5% of phosphoric acid, 2-5% of hydrogen donor, 0.5-1% of emulsifier and the balance of solvent, wherein the total amount is 100%; the oil-soluble metal catalyst is azacyclo-ferric carbine;

the heat generating agent comprises NaNO according to mass percentage₂10-30％，NH₄Cl 8-25%, acid initiator 3-10%, and water in balance, the total amount being 100%;

the water-soluble viscosity reducer comprises, by mass, 0.2-0.5% of a surfactant, 2-10% of an alkali and the balance of water, wherein the total amount is 100%.

The catalyst is prepared according to the following steps: dissolving azacarbene iron and tert-butyl hydroperoxide in a solvent, and then adding phosphoric acid, a hydrogen donor and an emulsifier for mixing to obtain the compound;

the gas injected into the gas injection slug is nitrogen or carbon dioxide;

the solvent is one or more of benzene, toluene, xylene, kerosene and diesel oil; and/or the hydrogen donor is one or more of methanol, ethanol, tetrahydronaphthalene, formic acid, formamide and glycerol; and/or the emulsifier is one or two of span 60 and span 80;

the acid initiator is one or more of phosphoric acid, hydrochloric acid, sulfuric acid and acetic acid;

the surfactant is alkylphenol ethoxylates;

the alkali is one or more of sodium hydroxide, potassium hydroxide, sodium carbonate and potassium carbonate.

The structural formula of the azacarbene in the present embodiment is as follows:

the azacarbene iron of the embodiment is prepared by the following steps:

adding 2, 6-diisopropylaniline, 40% glyoxal and formic acid into a third organic solvent, namely absolute ethyl alcohol, reacting for 2d, filtering, and washing with cold methanol to obtain the diaza-butadiene; wherein the molar ratio of the 2, 6-diisopropylaniline to the glyoxal is 2: 1; the yield of diazabetadine was 89.2%;

stirring paraformaldehyde and HCl (4M in dioxane) at 30 ℃ for 12 hours, then adding a mixture of diazadiene and THF, continuously stirring at room temperature for reacting for 4 hours, and filtering and washing to obtain the 1, 3-bis (2, 6-diisopropyl-1-phenyl) imidazolium chloride; the molar ratio of the diazabetadine, the paraformaldehyde, and the HCl is 1:1: 1; the yield of 1, 3-bis (2, 6-diisopropyl-1-phenyl) imidazolium chloride was 88.4%;

mixing 1, 3-bis (2, 6-diisopropyl-1-phenyl) imidazolium chloride and potassium tert-butoxide according to a molar ratio of 1:1, adding into a first organic solvent THF, stirring at room temperature for reaction for 4h, extracting with ethyl acetate, drying, and purifying to obtain the free N-heterocyclic carbene; the yield of the free azacyclo-carbene is 66.7 percent;

free azacyclo-carbene and anhydrous FeCl₃Adding the mixture into a second organic solvent THF according to a molar ratio of 1:1, stirring at room temperature for 30min, then drying in vacuum, filtering and washing by using a mixed solution of toluene and pentane, and then recrystallizing by using a mixed solution of THF and pentane to obtain an iron-based azacarbene catalyst, namely azacarbene iron, wherein the yield of the iron-based azacarbene catalyst is 57.6%; in FIG. 1, the azacarbene iron¹H NMR(C6D6):δ8.55(24H,CH₃),1.51(4H，＝CH),0.46(8H,CHMe₂),-2.20(8H,m-H),-2.89(24H,CH₃),-3.68(4H,p-H).μ_eff(Evans,C₆D₆):7.4(1)Μb.μ_eff(Evans,C₆D₆):5.8(1)μ_B.Anal.Calcd for C₂₇H₃₆Cl₃FeN₂:C,58.88；H,6.59；N,5.09.Found:C,57.54；H,6.61；N,4.67。

The specific embodiment also comprises an application of the combined catalytic viscosity reducer in the degradation of thick oil.

The application comprises the following steps:

s1, adding a catalyst and water into the thickened oil according to the mass ratio (3-4) of the water to the thickened oil to (6-7), wherein the dosage of the catalyst is 0.5-2% of the mass of the thickened oil;

s2, continuously adding a heat generating agent into the thick oil at the temperature of 50-60 ℃; specifically, first NaNO₂And NH₄Dissolving Cl in water, adding the solution into the thick oil, and then adding an acid initiator;

s3, continuing to inject gas into the thickened oil until the pressure reaches 4-6MPa, and then adding a water-soluble viscosity reducer for viscosity reduction for 2-4 h.

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

The thickened oils treated in the following examples had a viscosity of 154100mPa · s.

Example 1

The embodiment provides a combined catalytic viscosity reducer, which consists of four slugs, wherein the four slugs are a catalyst slug, a heat generating agent slug, a gas injection slug and a water-soluble viscosity reducer slug;

the catalyst slug comprises the following components in percentage by mass: 15% of oil-soluble metal catalyst azacyclo-carbine iron, 15% of tert-butyl hydroperoxide, 5% of phosphoric acid, 3% of hydrogen donor methanol, 601% of emulsifier span and the balance of solvent benzene, wherein the total amount is 100%;

the heat generating agent comprises NaNO according to mass percentage₂27.6％，NH₄21.2 percent of C, 3 percent of acid initiator hydrochloric acid and the balance of water, wherein the total amount is 100 percent;

the water-soluble viscosity reducer comprises, by mass, 0.5% of surfactant alkylphenol polyoxyethylene ether, 2% of sodium hydroxide and the balance of water, wherein the total amount is 100%.

The embodiment also includes the application of the combined catalytic viscosity reducer in the degradation of thick oil, and the method comprises the following steps:

s1, adding a catalyst and water into the thickened oil according to the mass ratio of 4:6 of the water to the thickened oil, wherein the dosage of the catalyst is 0.5% of the mass of the thickened oil;

s2, continuously adding a heat generating agent into the thick oil at the temperature of 60 ℃; specifically, first NaNO₂And NH₄Dissolving Cl in water, adding the solution into the thick oil, and then adding an acid initiator, namely hydrochloric acid; the using amount of the heat generating agent is 0.2 percent of the mass of the thick oil;

s3, continuously injecting nitrogen into the thickened oil until the pressure reaches 5MPa, and then adding a water-soluble viscosity reducer for viscosity reduction for 2 hours, wherein the using amount of the water-soluble viscosity reducer is 0.4% of the mass of the thickened oil.

Example 2

The embodiment provides a combined catalytic viscosity reducer, which consists of four slugs, wherein the four slugs are a catalyst slug, a heat generating agent slug, a gas injection slug and a water-soluble viscosity reducer slug;

the catalyst slug comprises the following components in percentage by mass: 10% of oil-soluble metal catalyst azacyclo-carbine iron, 30% of tert-butyl hydroperoxide, 3% of phosphoric acid, 2% of hydrogen donor methanol, 800.8% of emulsifier span and the balance of solvent toluene, wherein the total amount is 100%;

the heat generating agent comprises NaNO according to mass percentage₂10％，NH₄Cl 25%, acid initiator phosphoric acid 10%, and the balance water, the total amount being 100%;

the water-soluble viscosity reducer comprises, by mass, 0.2% of surfactant alkylphenol polyoxyethylene ether, 5% of sodium hydroxide and the balance of water, wherein the total amount is 100%.

The embodiment also includes the application of the combined catalytic viscosity reducer in the degradation of thick oil, and the method comprises the following steps:

s1, adding a catalyst and water into the thickened oil according to the mass ratio of 3:7 of the water to the thickened oil, wherein the dosage of the catalyst is 0.5% of the mass of the thickened oil;

s2, continuously adding a heat generating agent into the thick oil at the temperature of 50 ℃; specifically, first NaNO₂And NH₄Dissolving Cl in water, adding the solution into the thick oil, and then adding an acid initiator, namely hydrochloric acid; the using amount of the heat generating agent is 0.3 percent of the mass of the thick oil;

s3, continuously injecting nitrogen into the thickened oil until the pressure reaches 6MPa, and then adding a water-soluble viscosity reducer for viscosity reduction for 4 hours, wherein the using amount of the water-soluble viscosity reducer is 0.5% of the mass of the thickened oil.

Example 3

The embodiment provides a combined catalytic viscosity reducer, which consists of four slugs, wherein the four slugs are a catalyst slug, a heat generating agent slug, a gas injection slug and a water-soluble viscosity reducer slug;

the catalyst slug comprises the following components in percentage by mass: 12% of oil-soluble metal catalyst azacyclo-carbine iron, 20% of tert-butyl hydroperoxide, 2% of phosphoric acid, 5% of hydrogen donor methanol, 600.5% of emulsifier span and the balance of solvent xylene, wherein the total amount is 100%;

the heat generating agent comprises NaNO according to mass percentage₂30％，NH₄C18%, acid initiator sulfuric acid 5%, and the balance of water, the total amount being 100%;

the water-soluble viscosity reducer comprises, by mass, 0.3% of surfactant alkylphenol polyoxyethylene ether, 10% of sodium hydroxide and the balance of water, wherein the total amount is 100%.

The embodiment also includes the application of the combined catalytic viscosity reducer in the degradation of thick oil, and the method comprises the following steps:

s1, adding a catalyst and water into the thickened oil according to the mass ratio of 4:6 of the water to the thickened oil, wherein the dosage of the catalyst is 1% of the mass of the thickened oil;

s2, continuously adding a heat generating agent into the thick oil at the temperature of 60 ℃; specifically, first NaNO₂And NH₄Dissolving Cl in water, adding the solution into the thick oil, and then adding an acid initiator, namely hydrochloric acid; the using amount of the heat generating agent is 0.1 percent of the mass of the thick oil;

s3, continuously injecting nitrogen into the thickened oil until the pressure reaches 4MPa, and then adding a water-soluble viscosity reducer for viscosity reduction for 3 hours; the dosage of the water-soluble viscosity reducer is 0.4 percent of the mass of the thick oil.

Example 4

The embodiment provides a combined catalytic viscosity reducer, which consists of four slugs, wherein the four slugs are a catalyst slug, a heat generating agent slug, a gas injection slug and a water-soluble viscosity reducer slug;

the catalyst slug comprises the following components in percentage by mass: 10% of oil-soluble metal catalyst azacyclo-carbine iron, 30% of tert-butyl hydroperoxide, 4% of phosphoric acid, 4% of hydrogen donor methanol, 601% of emulsifier span and the balance of solvent benzene, wherein the total amount is 100%;

the heat generating agent comprises NaNO according to mass percentage₂15％，NH₄Cl 22%, acid initiator acetic acid 8%, and the balance water, the total being 100%;

the water-soluble viscosity reducer comprises, by mass, 0.3% of surfactant alkylphenol polyoxyethylene ether, 3% of sodium hydroxide and the balance of water, wherein the total amount is 100%.

The embodiment also includes the application of the combined catalytic viscosity reducer in the degradation of thick oil, and the method comprises the following steps:

s1, adding a catalyst and water into the thickened oil according to the mass ratio of 3:7 of the water to the thickened oil, wherein the dosage of the catalyst is 0.7% of the mass of the thickened oil;

s2, continuously adding a heat generating agent into the thick oil at the temperature of 60 ℃; specifically, first NaNO₂And NH₄Dissolving Cl in water, adding the solution into the thick oil, and then adding an acid initiator, namely hydrochloric acid; the using amount of the heat generating agent is 0.6 percent of the mass of the thick oil;

s3, continuously injecting nitrogen into the thickened oil until the pressure reaches 5MPa, and then adding a water-soluble viscosity reducer for viscosity reduction for 3 hours, wherein the using amount of the water-soluble viscosity reducer is 0.4% of the mass of the thickened oil.

Example 5

This example differs from example 1 in that the amount of catalyst used is 1.5% of the mass of the thick oil.

Example 6

This example differs from example 1 in that the amount of catalyst used is 2% by mass of the thick oil.

Example 7

The present embodiment adopts the combined catalytic viscosity reducer in example 1, and differs from example 1 in that the combined catalytic viscosity reducer is applied to the degradation of thick oil, in step S1, water is added to the thick oil according to the mass ratio of 7:3 of water to the thick oil, and other steps are the same as example 1.

Comparative example 1

The combined catalytic viscosity reducer of the present comparative example is different from example 1 in that the oil-soluble metal catalyst is 10% of iron oleate, and other components are the same as those of example 1; the use in the degradation of thick oils is otherwise the same as in example 1.

The viscosity reducing effects of examples 1 to 7 and comparative examples 1 to 2 are shown in Table 1.

The viscosity reduction ratio is calculated by the formula of [ (. eta.0-eta.)/. eta.0) × 100%, wherein. eta.0 and. eta.denote the viscosity of the oil sample before and after the reaction, respectively, and the unit is mPas.

TABLE 1 reduced cohesiveness fruits of examples 1-7 and comparative examples 1-2

	Viscosity reduction rate
		Example 1	96.5％
Example 2	91.3％
		Example 3	92.6％
Example 4	93.2％
		Example 5	94.6％
Example 6	94.8％
		Example 7	92.5％
Comparative example 1	60.8％

In example 1, after the viscosity of 154100mPa · s thick oil is reduced, the final viscosity reduction rate is 96.5%, the crude oil is rapidly dispersed and is in a crushed particle form, the colloid content is greatly reduced, and the aromatic hydrocarbon content is greatly increased;

the viscosity reduction rate of example 2 after 4 hours is lower than that of example 1, which is probably because aromatic components and colloid are easy to condense to generate asphaltene under aerobic conditions, and side chains in the cyclic molecules of the colloid are unstable and are easy to break under certain conditions; because the decarboxylation reaction is carried out to generate corresponding micromolecule hydrocarbon substances, the content of the saturated component can be increased, but the saturated component can be continuously oxidized to generate macromolecular substances such as colloid asphaltene and the like after the continuous extension of time, and the viscosity reduction rate of the thickened oil is reduced;

the reason for the lower viscosity reduction rate of example 3 may be that the viscosity reduction effect is deteriorated due to the smaller addition amount of the emulsifier, the larger dispersed particles of the crude oil;

the reason why the viscosity reduction rate of example 4 is lower than that of example 1 may be that the viscosity reduction rate is reduced because the addition amount of the heat generating agent is increased and the temperature rise range is increased, and because in a limited space, the oxidation reaction of the crude oil approaches the limit and the asphaltene content is increased as the reaction proceeds;

as can be seen from examples 5 to 6, a relatively increased amount of catalyst had little effect on the viscosity reduction of the thick oil.

The lower viscosity reduction of example 7 indicates that increasing the water content results in a lower viscosity reduction of the thickened oil, since as the water content increases, an oil-in-water state is formed, forming a film of polar water molecules on the surface of the thickened oil molecules, which inhibits or slows down some of the oxidation reactions.

As can be seen from the de-caking fruit of comparative example 1, the de-caking rate of iron oleate was only 60.8% with the oil-soluble metal catalyst.

The combined catalytic viscosity reducer integrates catalytic oxidation, chemical viscosity reduction, self-heating and gas injection, has better low-temperature catalytic oxidation performance for common thickened oil, extra thickened oil, super thickened oil and offshore thickened oil samples, can be applied to thickened oil old areas, offshore and difficultly-used thickened oil reservoirs after steam injection thermal extraction, and can reduce heat consumption, save cost, increase saturated components in reaction products and reduce colloid components in the thickened oil during thickened oil extraction compared with hydrothermal cracking catalytic viscosity reduction.

The above-described embodiments of the present invention should not be construed as limiting the scope of the present invention. Any other corresponding changes and modifications made according to the technical idea of the present invention should be included in the protection scope of the claims of the present invention.