Lignin-based plugging agent raw material composition, lignin-based plugging material and preparation method thereof

Abstract

The present invention relates to the technical field of oil extraction, and discloses a lignin-based plugging agent raw material composition, a lignin-based profile control material and a preparation method thereof. The lignin-based plugging agent raw material composition comprises: nano-hydroxymethylated lignin, an anionic acrylamide polymer, a water-soluble phenolic resin crosslinking agent and an oxygen scavenger. The lignin-based profile control material of the present invention can form a low-strength gel at reservoir temperature, preventing the gelling solution from being rapidly diluted underground. After injecting steam, it can be rapidly crosslinked secondarily into a high-strength gel, realizing effective plugging of steam channeling channels in a long time range under the environment of ultra-high temperature of 200-250 °C and salinity ≤ 100000 mg / L. It has the characteristics of large plugging strength, wide application range and high plugging efficiency. Nano-hydroxymethylated lignin can also effectively reduce the usage amount of the water-soluble phenolic resin crosslinking agent, reduce the production cost of the high-temperature channeling plugging agent, and meet the requirements of simple on-site construction operation and economy.

Description

Technical Field

[0001] The present invention relates to the technical field of oil production, and in particular to a lignin-based plugging agent raw material composition, a lignin-based plugging material and a preparation method thereof, an application of the lignin-based plugging agent raw material composition or the lignin-based plugging material in oil reservoir production, and an oil reservoir production method. Background Art

[0002] my country has abundant reserves of heavy oil reservoirs, and steam huff and puff is the main development method. At present, the main thermal recovery oil fields have entered the multi-round huff and puff stage. The reservoir is highly heterogeneous, and many wells have serious inter-well steam channeling during steam injection. The injected steam migrates along the channeling channel, resulting in ineffective steam displacement in the large pores, and the goal of heating the oil layer near the wellbore area of ​​the huff and puff well cannot be achieved. As a result, the oil-gas ratio is low and the thermal recovery effect is poor after multiple rounds of huff and puff. At the same time, the edge and bottom water advances along the high permeability zone, causing large-scale water flooding of the oil wells, restricting the normal production of the oil wells.

[0003] Plugging and adjustment technology is one of the main technologies for adjusting the thermal flow field and improving the utilization rate of steam. Currently, the commonly used plugging agents include high-temperature gel, foam, solid particles, resin plugging agents, etc. High-temperature gel is the most widely used and has achieved relatively significant results. The main agent of its gelling liquid is acrylamide polymer, lignin, tannin extract and other macromolecules. Among them, the high-temperature gel formed by acrylamide polymer as the main agent has the advantages of adjustable gelling temperature, adjustable strength, good toughness, etc., but under high steam temperature, the gel grid is easy to escape from the internal bound water due to chain breakage or structural compression, and it is easy to dehydrate and fail. The plugging agent with biological macromolecules such as lignin as the main agent has good high temperature resistance and high strength. However, due to the defects of low hydroxyl content and large reaction steric hindrance on the aromatic ring in the main structure of lignin, the reaction activity is low. In practical applications, there are problems such as large amount of cross-linking agent and poor brittleness. How to provide a plugging agent that can achieve effective water blocking for a long time at high temperature is an urgent problem to be solved in the field of plugging and adjustment. Summary of the invention

[0004] In view of the problem that existing gel plugging agents cannot be effectively applied to ultra-high temperatures and achieve long-term water plugging, the purpose of the present invention is to provide a lignin-based plugging agent raw material composition, a lignin-based plugging material and its preparation method, the application of the lignin-based plugging agent raw material composition or the lignin-based plugging material in oil reservoir exploitation, and a method for oil reservoir exploitation. The lignin-based plugging material prepared from the lignin-based plugging agent raw material composition of the present invention can form a low-strength gel within the temperature range of (60-90°C) at the oil reservoir temperature, prevent the gelling liquid from being rapidly diluted under the formation, and quickly cross-link to form a high-strength frozen gel after steam injection, so as to effectively block the steam channel within 60 days under the ultra-high temperature of 200-250°C and the mineralization degree ≤100000mg / L, thereby realizing the efficient development of heavy oil reservoirs.

[0005] To achieve the above object, a first aspect of the present invention provides a lignin-based plugging agent raw material composition, which comprises: nano-hydroxymethylated lignin, an anionic acrylamide polymer, a water-soluble phenolic resin crosslinking agent, and a deoxidizer.

[0006] Preferably, the lignin-based plugging agent raw material composition further contains a solvent, and the solvent is preferably water.

[0007] Preferably, based on the total weight of the lignin-based plugging agent raw material composition, the content of the nano-hydroxymethylated lignin is 3.5-10% by weight, the content of the anionic acrylamide polymer is 0.06-0.4% by weight, the content of the water-soluble phenolic resin crosslinking agent is 2-6% by weight, the content of the deoxidizer is 0.002-0.1% by weight, and the content of the solvent is 83.5-94.438% by weight.

[0008] Preferably, the water-soluble phenolic resin crosslinking agent is a water-soluble prepolymer of phenolic raw materials and aldehyde raw materials.

[0009] Preferably, the phenolic raw materials include a first phenolic raw material and a second phenolic raw material. Among them, the first phenolic raw material is at least one of phenol, cresol, hydroquinone, catechol, and resorcinol, more preferably phenol; the second phenolic raw material is a phenolic compound containing a bridging oxygen atom;

[0010] More preferably, the second phenolic raw material has the structure shown in formula (1), wherein R1 and R2 are each independently selected from H or an alkoxy group, and R3 is selected from one of H, methyl, ethyl, methoxy, and ethoxy;

[0011]

[0012] Even more preferably, the alkoxy group is selected from one of methoxy, ethoxy, and propoxy.

[0013] Preferably, the aldehyde raw material is one or more of formaldehyde, acetaldehyde, paraformaldehyde, and furfural, more preferably formaldehyde.

[0014] A second aspect of the present invention provides a method for preparing a lignin-based profile control material, which comprises:

[0015] In the presence of a solvent, after mixing nano-hydroxymethylated lignin and an anionic acrylamide polymer, they are mixed with a water-soluble phenolic resin crosslinking agent and a deoxidizer to obtain the lignin-based profile control material.

[0016] A third aspect of the present invention provides a lignin-based profile control material prepared by the method as described above.

[0017] The fourth aspect of the present invention provides the application of the lignin-based plugging agent raw material composition or the lignin-based profile control material as described above in oil reservoir exploitation, particularly in the thermal recovery of heavy oil by steam stimulation.

[0018] The fifth aspect of the present invention provides a method for oil reservoir exploitation, which includes: injecting the lignin-based profile control material as described above into the formation, so that the lignin-based profile control material crosslinks in situ in the formation to form a gel.

[0019] In the present invention, by utilizing the reaction at the ortho-position of the phenolic hydroxyl group of lignin, hydroxymethyl groups with greater reactivity are introduced at the ortho-position of the aromatic ring phenolic hydroxyl group and the side chain of lignin. After nanosizing it, the interaction with the polymer can be increased, and the reactivity of lignin can be improved. Taking the nano-hydroxymethylated lignin as a rigid material and introducing it into the traditional polyacrylamide gel system, through the crosslinking reaction of the nano-hydroxymethylated lignin, acrylamide polymer and water-soluble phenolic resin crosslinking agent (especially in the case of the water-soluble phenolic resin crosslinking agent preferably selected in the present invention), an interpenetrating network combining flexibility and rigidity with an interpenetrating network of flexible network and rigid network is formed. Its unique network structure and synergistic effect endow it with stronger plugging ability and profile improvement ability. It can not only improve the high-temperature resistance of the existing acrylamide gels, but also endow the traditional lignin plugging agent with a certain toughness while maintaining strength, effectively improving the long-term temperature resistance and extending the plugging validity period, and enhancing the added value of lignin-based polymers.

[0020] At the same time, due to the increased activity of the nano-hydroxymethylated lignin compared with that before modification, the usage amount of the water-soluble phenolic resin crosslinking agent can be effectively reduced, the production cost of the high-temperature plugging agent for channeling prevention is reduced, and the requirements of simple on-site construction operation and economy are met.

[0021] The preparation method of the lignin-based profile control material provided by the present invention is simple, the formed gel has good stability and high strength, and can effectively plug the water channeling channels for a long time within 60 days under the environment of ultra-high temperature of 200 - 250 °C and salinity ≤ 100000 mg / L. It has a higher plugging rate and a longer plugging time, and can be applied to the plugging operation of large channels in the thermal recovery operation of heavy oil by steam stimulation. Detailed Embodiments

[0022] In the ranges disclosed herein, the endpoints and any values are not limited to the exact ranges or values. These ranges or values should be understood to include values close to these ranges or values. For numerical ranges, between the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values, they can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein.

[0023] To achieve the above object, a first aspect of the present invention provides a lignin-based plugging agent raw material composition, which comprises: nano-hydroxymethylated lignin, an anionic acrylamide polymer, a water-soluble phenolic resin crosslinking agent, and an oxygen scavenger.

[0024] Each component in the lignin-based plugging agent raw material composition can be stored separately or two or more components can be stored together. When the lignin-based plugging agent raw material composition is used, a solvent is required to be present, but it can also be sold as a product without a solvent, and a predetermined amount of solvent can be added when in use.

[0025] In the present invention, based on the total weight of the lignin-based plugging agent raw material composition, the content of the nano-hydroxymethylated lignin is 3.5-10% by weight, such as 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, 10% by weight and any range composed of any two values, preferably 4.5-8% by weight.

[0026] Preferably, the average particle size of the nano-hydroxymethylated lignin is 20-100 nm.

[0027] The particle size parameter can be measured by the Malvern Zetasizer laser particle size analyzer method.

[0028] Preferably, the hydroxymethyl content of the nano-hydroxymethylated lignin is 8-13% by weight.

[0029] The method for determining the hydroxymethyl content can be referred to the national standard GB / T14074.17-2006 "Testing Methods for Wood Adhesives and Their Resins - Determination Method for Hydroxymethyl Content".

[0030] The nano-hydroxymethylated lignin can be prepared by conventional methods in the art.

[0031] In a preferred embodiment of the present invention, the preparation method of the nano-hydroxymethylated lignin includes: under alkaline conditions, the lignin raw material is contacted with an aldehyde modifier for reaction to obtain nano-hydroxymethylated lignin.

[0032] The alkaline conditions can be provided by an alkaline pH regulator. Preferably, the alkaline pH regulator is a soluble base, selected from at least one of sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium carbonate, sodium bicarbonate, ammonia water, strontium hydroxide, rubidium hydroxide, cesium hydroxide, thallium(I) hydroxide, and radium hydroxide.

[0033] Preferably, in the reaction system, the addition amount of the alkaline pH regulator is 0.5-5% by weight, more preferably 0.8-3% by weight.

[0034] Preferably, the lignin raw material is selected from at least one of alkali lignin, enzymatic hydrolysis lignin, chlorinated lignin, steam exploded lignin, lignosulfonate (such as sodium salt), and sulfur lignin, and more preferably at least one of alkali lignin, enzymatic hydrolysis lignin, and sodium lignosulfonate.

[0035] Preferably, the effective content of lignin in the lignin raw material is 80% by weight or more.

[0036] When the lignin raw material contacts with the aldehyde modifier, it preferably exists in the form of an aqueous solution of the lignin raw material.

[0037] In a preferred embodiment of the present invention, the preparation method of the aqueous solution of the lignin raw material is to disperse and dissolve the lignin raw material at a high shear rate. In order to accelerate the dissolution rate, the temperature during preparation can be increased, for example, it can be carried out at 25 - 55°C. It should be understood that in order to accelerate the dissolution, the alkaline pH regulator can also be mixed with the lignin raw material first.

[0038] Preferably, the concentration of lignin in the aqueous solution of the lignin raw material is 6 - 12% by weight.

[0039] Preferably, the aldehyde modifier is selected from at least one of formaldehyde, acetaldehyde, glyoxal, glutaraldehyde, acrolein, paraformaldehyde, and furfural. When the aldehyde modifier contains at least two substances, the dosage ratio is any ratio.

[0040] The aldehyde modifier can be obtained through commercial purchase.

[0041] Preferably, the mass ratio of the aldehyde modifier to the lignin raw material is 0.1 - 0.9:1, such as 0.1:1, 0.3:1, 0.5:1, 0.7:1, 0.9:1, and any range composed of any two values.

[0042] In the present invention, there are no specific limitations on the contact reaction method and conditions, as long as the hydroxymethylation modification of lignin can be achieved. For example, the aldehyde modifier can be added to the lignin raw material solution multiple times, and when adding, the flow rate can be controlled slowly. The inventor found in the research that under alkaline conditions, the nano-hydroxymethylated lignin obtained under the hydroxymethylation conditions of a temperature of 70 - 90°C and a time of 2 - 6 h can achieve better results when used in a high-temperature plugging system.

[0043] In the present invention, after the reaction is completed, the reaction material can be cooled to room temperature, and the nano-hydroxymethylated lignin can be subjected to activation treatment.

[0044] The activation treatment method can be acidification treatment.

[0045] The acid treatment can be achieved using conventional acidic substances in the art, and the acidic substances can be at least one of hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, acetic acid, and oxalic acid.

[0046] Preferably, the acidic substance exists in the form of a solution. Preferably, the concentration of the acidic substance in the acidic substance solution is 0.2-4% by weight.

[0047] Preferably, the conditions for the activation treatment include: pH is 2-3, and the time is 10-60 min.

[0048] In the present invention, the nano-hydroxymethylated lignin after the activation treatment can also be purified through post-treatment, and the purification method can be a conventional purification method in the art. For example, the mixture solution obtained after the reaction is centrifuged, then washed repeatedly, and finally dried under vacuum.

[0049] In the present invention, preferably, based on the total weight of the lignin-based plugging agent raw material composition, the content of the anionic acrylamide polymer is 0.06-0.4% by weight, such as 0.06, 0.08, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4% by weight and any range composed of any two values, preferably 0.08-0.2% by weight.

[0050] In the present invention, the types of the anionic acrylamide polymers can be selected with reference to the prior art. For the present invention, preferably, the anionic acrylamide polymer is selected from at least one of partially hydrolyzed polyacrylamide, acrylamide / acrylic acid (sodium) / N-vinylpyrrolidone copolymer, acrylamide / acrylic acid (sodium) / AMPS (sodium) copolymer, acrylamide / AMPS (sodium) copolymer, and acrylamide / acrylic acid (sodium) / acrylonitrile copolymer, and more preferably acrylamide / AMPS (sodium) copolymer and / or acrylamide / acrylic acid (sodium) / AMPS (sodium) copolymer.

[0051] Among them, the partially hydrolyzed polyacrylamide can be prepared by the hydrolysis reaction of polyacrylamide or the copolymerization reaction of acrylamide and acrylic acid.

[0052] Among them, AMPS (sodium) refers to 2-acrylamido-2-methylpropanesulfonic acid (sodium).

[0053] The anionic acrylamide polymer can be synthesized according to the prior art or obtained by commercial purchase. For example, it can be the acrylamide / AMPS copolymer purchased from Dongying Baomo Environmental Engineering Co., Ltd.

[0054] In the present invention, preferably, the viscosity-average molecular weight of the anionic acrylamide polymer is 10 million - 30 million, more preferably 15 million - 25 million.

[0055] In the present invention, preferably, the degree of hydrolysis of the anionic acrylamide polymer is 10 - 25%, more preferably 15 - 20%.

[0056] In the present invention, the degree of hydrolysis is measured by the national standard GB / T12005.6 - 1989 Determination Method for the Degree of Hydrolysis of Partially Hydrolyzed Polyacrylamide.

[0057] In the present invention, the water-soluble phenolic resin crosslinking agent can be any water-soluble phenolic resin in the art, and the water-soluble phenolic resin crosslinking agent can be a water-soluble prepolymer of phenolic raw materials and aldehyde raw materials.

[0058] The phenolic raw materials can be existing phenolic raw materials in the art and can be at least one phenolic raw material. Preferably, the phenolic raw materials include a first phenolic raw material and a second phenolic raw material.

[0059] Preferably, the first phenolic raw material is at least one of phenol, cresol (such as o-cresol, m-cresol, p-cresol), hydroquinone, catechol, and resorcinol, more preferably phenol.

[0060] Preferably, the second phenolic raw material is a phenolic compound containing a bridging oxygen atom.

[0061] Preferably, the second phenolic raw material has the structure shown in formula (1), wherein R1 and R2 are each independently selected from H or an alkoxy group, and R3 is selected from one of H, methyl, ethyl, methoxy, and ethoxy;

[0062]

[0063] Preferably, the alkoxy group is selected from one of methoxy, ethoxy, or propoxy.

[0064] Preferably, the second phenolic raw material is selected from at least one of p-methoxyphenol, p-ethoxyphenol, p-propoxyphenol, guaiacol, 2-methoxy-4-methylphenol, o-ethoxyphenol, and o-propoxyphenol, more preferably selected from ethoxyphenol and guaiacol.

[0065] The content ratio of the first phenolic raw material and the second phenolic raw material can be selected within a relatively wide range. Preferably, the weight ratio of the first phenolic raw material to the second phenolic raw material is 1:0.05 - 0.5, more preferably 1:0.07 - 0.4.

[0066] The aldehyde raw material can be a conventional aldehyde raw material in the art. Preferably, the aldehyde raw material is at least one of formaldehyde, acetaldehyde, paraformaldehyde, and furfural, and more preferably formaldehyde.

[0067] Preferably, the molar ratio of the phenolic raw material to the aldehyde raw material is 1:1.2 - 2, for example, it can be 1:1.2, 1:1.3, 1:1.4, 1:1.5, 1:1.6, 1:1.7, 1:1.8, 1:1.9, 1:2, and any range formed between any two values.

[0068] The water-soluble phenolic resin crosslinking agent can be prepared according to the conventional methods in the art. The following provides a preferred preparation method, under which the performance of the final product can be further improved.

[0069] In a preferred embodiment of the present invention, the preparation method of the water-soluble phenolic resin crosslinking agent includes: heating and melting the first phenolic raw material, reacting with a part of the alkali catalyst and a part of the aldehyde raw material at 50 - 70°C for 1 - 4 h, adding the remaining part of the alkali catalyst at 75 - 90°C, and continuing the reaction for 20 - 40 min, and then reacting with the second phenolic raw material and the remaining part of the aldehyde raw material for 0.5 - 2 h to obtain the water-soluble phenolic resin crosslinking agent.

[0070] The types and dosage ratios of the first phenolic raw material, the aldehyde raw material, and the second phenolic raw material have been described above and will not be elaborated here.

[0071] Preferably, the part of the aldehyde raw material accounts for 75 - 90% by weight of the total amount of the aldehyde raw material.

[0072] The aldehyde raw material can also exist in a conventional form. For example, formaldehyde can exist in the form of an aqueous solution (formaldehyde concentration is 30 - 50% by weight), and paraformaldehyde exists in a solid form.

[0073] In the present invention, after the reaction, the water-soluble phenolic resin crosslinking agent product can be obtained by discharging through cooling and reduced-pressure distillation (the temperature can be 30 - 60°C) or cooling to below 40°C and then directly discharging.

[0074] Among them, the alkali catalyst can be one or more of sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium carbonate, sodium bicarbonate, triethylamine, barium hydroxide, and zinc acetate, and preferably sodium hydroxide.

[0075] The dosage of the alkali catalyst can be selected within a relatively wide range. Preferably, compared with 1 mol of the aldehyde raw material, the dosage of the alkali catalyst is 0.25 - 0.35 mol.

[0076] Preferably, the partial alkali catalyst accounts for 50-75% by weight of the total amount of the alkali catalyst.

[0077] The alkali catalyst can be added in the form of a solution, and the concentration in the solution of the alkali catalyst is 30-60% by weight.

[0078] The reaction can be carried out in a three-necked flask equipped with a stirrer and a condenser.

[0079] It should be understood that the crosslinking agent prepared under the above preferred conditions is more conducive to preparing a plugging agent with excellent plugging performance.

[0080] The degree of polymerization of the water-soluble phenolic resin crosslinking agent is preferably 2-5, and the weight average molecular weight is preferably 200-600.

[0081] Preferably, the pH of the water-soluble phenolic resin crosslinking agent is 9-11.

[0082] In the present invention, preferably, based on the total weight of the lignin-based plugging material, the content of the water-soluble phenolic resin crosslinking agent is 2-6% by weight, such as 2, 2.2, 2.4, 2.6, 2.8, 3, 3.2, 3.4, 3.6, 3.8, 4, 4.2, 4.4, 4.6, 4.8, 5, 5.2, 5.4, 5.6, 5.8, 6% by weight and any range composed of any two values, preferably 3-4.5% by weight.

[0083] In the present invention, the weight of the water-soluble phenolic resin crosslinking agent is calculated based on the actual weight of the additive.

[0084] In the present invention, preferably, based on the total weight of the lignin-based plugging agent raw material composition, the content of the deoxidizer is 0.002-0.1% by weight, such as 0.002, 0.005, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1% by weight and any range composed of any two values, preferably 0.005-0.05% by weight.

[0085] In the present invention, the type and dosage of the deoxidizer can be selected with reference to the prior art. For the present invention, preferably, the deoxidizer is at least one of sodium thiosulfate, sodium sulfite, sodium bisulfite, sodium dithionite, isoascorbic acid, and thiourea.

[0086] In a preferred embodiment of the present invention, the lignin-based plugging agent raw material composition comprises: nano-hydroxymethylated lignin, an anionic acrylamide polymer, a water-soluble phenolic resin crosslinking agent, and a deoxidizer. Among them, the weight ratio of the nano-hydroxymethylated lignin, the anionic acrylamide polymer, the water-soluble phenolic resin crosslinking agent, and the deoxidizer is (3.5 - 10):(0.06 - 0.4):(2 - 6):(0.002 - 0.1), more preferably (4.5 - 8):(0.08 - 0.2):(3 - 4.5):(0.005 - 0.05). Among them, the weight ratio of each component can also be a ratio composed of any point value within the range.

[0087] Each component in the lignin-based plugging agent raw material composition can be stored separately or two or more of them can be stored together. The lignin-based plugging agent raw material composition requires the presence of a solvent during use, but it can also be sold as a product without a solvent and can be formulated with a predetermined amount of solvent when in use.

[0088] Preferably, the lignin-based plugging agent raw material composition further contains a solvent.

[0089] Preferably, the solvent is water.

[0090] Water, as the solvent and reaction medium in the lignin-based plugging material system, is not particularly limited in the present invention. The water can be natural water and artificially prepared water. Natural water can be river water, lake water, atmospheric water, seawater, groundwater, etc., and artificially prepared water can be tap water, distilled water, deionized water, or heavy water.

[0091] Generally speaking, in the actual application process, the water used is often the water at the oilfield location or its corresponding simulated brine. Preferably, the salinity of the water ≤ 100000 mg / L.

[0092] It should be understood that according to the different salinity of the water, the lignin-based plugging material composition will contain impurities from the water, but in the calculation process, it is calculated as a whole with the water.

[0093] In a preferred embodiment of the present invention, based on the total weight of the lignin-based plugging agent raw material composition, the content of the nano-hydroxymethylated lignin is 3.5 - 10% by weight, the content of the anionic acrylamide polymer is 0.06 - 0.4% by weight, the content of the water-soluble phenolic resin crosslinking agent is 2 - 6% by weight, the content of the deoxidizer is 0.002 - 0.1% by weight, and the content of the solvent is 83.5 - 94.438% by weight.

[0094] More preferably, based on the total weight of the lignin-based plugging agent raw material composition, the content of the nano-hydroxymethylated lignin is 4.5-8% by weight, the content of the anionic acrylamide polymer is 0.08-0.2% by weight, the content of the water-soluble phenolic resin crosslinking agent is 3-4.5% by weight, the content of the deoxidizer is 0.005-0.05% by weight, and the content of the solvent is 87.25-92.415% by weight.

[0095] Within the preferred range, the gelation strength and plugging performance of the lignin-based plugging material can be further improved.

[0096] In the present invention, unless otherwise specified, the reagents and materials used are conventional reagents and materials in the art and can be obtained through commercial purchase.

[0097] The second aspect of the present invention provides a method for preparing a lignin-based plugging material, the method comprising:

[0098] In the presence of a solvent, after mixing the nano-hydroxymethylated lignin and the anionic acrylamide polymer, they are mixed with the water-soluble phenolic resin crosslinking agent and the deoxidizer to obtain the lignin-based plugging material.

[0099] In the present invention, the addition method of the nano-hydroxymethylated lignin and the anionic acrylamide polymer is preferably to first add the anionic acrylamide polymer and stir for 0.5 h-1.5 h, and then add the nano-hydroxymethylated lignin. After the above two materials are fully dissolved, the water-soluble phenolic resin crosslinking agent and the deoxidizer are added and mixed.

[0100] The conditions and methods of the mixing may not be particularly limited as long as the materials can be fully dissolved. During the mixing process, in order to accelerate dissolution and mixing, methods such as stirring and ultrasonic can be used to assist mixing, so that each material dissolves faster and is evenly distributed.

[0101] The mixing can be carried out under normal temperature and pressure, which can be determined according to the specific environment when preparing the plugging material.

[0102] In a preferred embodiment of the present invention, based on the total weight of the lignin-based plugging material, the dosage of the nano-hydroxymethylated lignin is 3.5-10% by weight, the dosage of the anionic acrylamide polymer is 0.06-0.4% by weight, the dosage of the water-soluble phenolic resin crosslinking agent is 2-6% by weight, the dosage of the deoxidizer is 0.002-0.1% by weight, and the dosage of the solvent is 83.5-94.438% by weight.

[0103] In a preferred embodiment of the present invention, based on the total weight of the lignin-based plugging material, the amount of the nano-hydroxymethylated lignin is 4.5-8% by weight, the amount of the anionic acrylamide polymer is 0.08-0.2% by weight, the amount of the water-soluble phenolic resin cross-linking agent is 3-4.5% by weight, the amount of the deoxidizer is 0.005-0.05% by weight, and the amount of the solvent is 87.25-92.415% by weight.

[0104] The types and properties of each component and the preparation method have been described in detail in the first aspect and will not be repeated here.

[0105] The solvent used may be the solvent described in the first aspect.

[0106] The third aspect of the present invention provides a lignin-based plugging material prepared by the method described above.

[0107] A fourth aspect of the present invention provides the use of the lignin-based plugging agent raw material composition or the lignin-based plugging material as described above in oil reservoir exploitation, especially in heavy oil steam huff and puff thermal recovery.

[0108] A fifth aspect of the present invention provides a method for oil reservoir exploitation, the method comprising: injecting the above-mentioned lignin-based plugging material into a formation, so that the lignin-based plugging material is cross-linked in situ in the formation to form a gel.

[0109] According to the present invention, after the composition is gelled, it can form a plug at an ultra-high temperature of 200-250° C. and a mineralization degree of ≤100,000 mg / L, and can be maintained at this temperature for at least 60 days.

[0110] The lignin-based plugging material of the present invention is suitable for heavy oil steam huff-and-puff thermal recovery operations. Preferably, the mineralization of water in the area where the thermal recovery operations are performed is below 100,000 mg / L.

[0111] The present invention will be described in detail below through examples.

[0112] In the following examples, anionic acrylamide polymers were purchased from Dongying Baomo Environmental Engineering Co., Ltd.

[0113] Enzymatic lignin was purchased from Beijing Longli Biotechnology Co., Ltd., with an effective content of 94.8% by weight.

[0114] Alkali lignin was purchased from Beijing Inokai Technology Co., Ltd.

[0115] Sodium lignin sulfonate was purchased from Beijing Jiahe Wood Technology Co., Ltd.

[0116] Paraformaldehyde was purchased from Beijing Bailingwei Technology Co., Ltd.

[0117] Acetaldehyde was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.

[0118] o-Cresol was purchased from Sigma-Aldrich (Shanghai) Trading Co., Ltd.

[0119] Guaiacol was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.

[0120] p-Ethoxyphenol was purchased from Beijing Bailingwei Technology Co., Ltd.

[0121] The formaldehyde aqueous solution was purchased from Bailingwei Technology Co., Ltd. The concentration of formaldehyde in the formaldehyde aqueous solution was 37% by weight. Unless otherwise specified, the weight of formaldehyde described in the following preparation examples and embodiments is based on the weight of the formaldehyde aqueous solution.

[0122] Unless otherwise specified, the reagents and materials used in the following examples are all commercially available.

[0123] In the following examples, simulated brine was prepared according to applicable reservoir environment, and the salinity of the simulated brine was 100,000 mg / L (it should be understood that the salinity is an approximate value).

[0124] In the following embodiments, the plugging performance is tested using the Darcy principle, and the test method is as follows:

[0125] Fill a simulated core (core diameter d = 25mm, length L = 200mm), and after evacuation, inject water into the core at a flow rate of 2 ml / min (injection rate Q), and measure the core permeability before plugging (k0); then inject 1.0-1.5PV high-temperature resistant plugging agent into the core model, plug both ends of the core with wire plugs, put the core in a constant temperature box at a certain temperature and let it stand for a certain period of time, and inject water again until the pressure is stable, and obtain the core permeability after plugging (k'), so as to calculate the plugging rate.

[0126] The plugging rate (η) is used as a parameter to characterize the plugging performance of the plugging agent, and the calculation formula is:

[0127] In the following examples and comparative examples, the polymer gel plugging agent gels at a specific temperature. The gelation time is determined by the gel strength code method, and the time taken for the gel system to be converted from a solution to a strength code G is defined as the gelation time.

[0128] In the following examples and comparative examples, the thermal stability is reflected by the dehydration rate, and the stability is examined by measuring the dehydration rate at different times. Measurement method: Place the polymer gel plugging agent gel solution in a closed stainless steel reactor, place it in a constant temperature box for reaction, take it out of the constant temperature box at fixed intervals, and weigh the mass of water removed from the gel on a balance. The ratio of this mass to the mass of the initial gel solution is the dehydration rate.

[0129] Colloid strength test:

[0130] The colloid strength was tested by the breakthrough vacuum degree method. The specific operation was as follows: The gelled colloid was placed into the test bottle of the breakthrough vacuum degree experimental device. The tip of a 1 mL pipette was inserted 1 cm below the colloid surface. The vacuum pump was started, and the knob was slowly adjusted to increase the system vacuum degree. When air broke through the colloid, the maximum reading of the vacuum degree on the vacuum gauge was the breakthrough vacuum degree of the gel. Each sample was measured 3 times, and the arithmetic mean was taken as its final strength value.

[0131] Particle size test:

[0132] A certain amount of hydroxymethylated modified lignin was added to 100 g of deionized water. After stirring until fully dissolved, about 1.5 mL of the solution was taken to measure the particle size with a Zeta Nanosizer particle size analyzer.

[0133] Determination of hydroxymethyl content:

[0134] It was carried out with reference to the national standard GB / T14074.17 - 2006 "Testing Methods for Wood Adhesives and Their Resins - Method for Determination of Hydroxymethyl Content".

[0135] Preparation Example 1

[0136] This preparation example was used to illustrate the preparation of nano - hydroxymethylated lignin HML - 1.

[0137] (1) At room temperature, 6 g of sodium lignosulfonate was weighed and added to 89.2 g of deionized water. It was dispersed at a high speed of 5000 rpm in a disperser for 30 minutes to obtain a uniformly dispersed aqueous solution of sodium lignosulfonate.

[0138] (2) The obtained aqueous solution of sodium lignosulfonate and 0.8 g of solid NaOH were added to a reactor equipped with a stirrer and a condenser, stirred evenly and heated to 50 °C, and kept at a constant temperature for 60 min.

[0139] (3) Then the system was heated to the set temperature of 70 °C within 1 h. 4 g of paraformaldehyde was slowly added in two portions at intervals of 30 minutes with stirring, and continued to stir for full reaction for 4 h;

[0140] (4) After the reaction was completed, it was quickly cooled to room temperature, the pH was adjusted to 3.0 with HCl, and the product was precipitated after activation. It was separated at 5000 rpm / min, and the lower - layer precipitate was taken, washed 3 times with distilled water, and dried to obtain the product nano - hydroxymethylated lignin HML - 1.

[0141] It was determined that the particle size of the original sodium lignosulfonate was 2 - 6 μm, the average particle size of the modified HML - 1 was 70 nm, and the hydroxymethyl content was 10.1 wt%.

[0142] Preparation Example 2

[0143] This preparation example is used to illustrate the preparation of nano-hydroxymethylated lignin HML-2.

[0144] (1) At room temperature, weigh 10 g of enzymatically hydrolyzed lignin and 0.6 g of solid NaOH, add them to 81.4 g of deionized water, stir for 30 minutes, and disperse at a high speed of 10000 rpm in a disperser for 30 minutes to obtain a uniformly dispersed aqueous solution of enzymatically hydrolyzed lignin.

[0145] (2) Add the obtained aqueous solution of enzymatically hydrolyzed lignin and 1.2 g of solid NaOH to a reactor equipped with a stirrer and a condenser, stir evenly and heat up to 50 °C, and keep the temperature constant for 120 min.

[0146] (3) Then raise the temperature of the system to the set temperature of 80 °C within 1 h, and slowly add 6.8 g of aqueous formaldehyde solution in three portions at intervals of 30 minutes with stirring, continue stirring, and carry out a sufficient reaction for 3 h;

[0147] (4) After the reaction is completed, quickly cool to room temperature, adjust the pH to 2.0 with HCl, activate to precipitate the product, separate at 8000 rpm / min, take the lower-layer precipitate, wash it 3 times with distilled water, and dry to obtain the product nano-hydroxymethylated lignin HML-2.

[0148] It was measured that the particle size of the original enzymatically hydrolyzed lignin was 1 - 10 μm, and the average particle size of the modified HML-2 was 50 nm, and the hydroxymethyl content was 12.6 wt%.

[0149] Preparation Example 3

[0150] This preparation example is used to illustrate the preparation of nano-hydroxymethylated lignin HML-3.

[0151] (1) At room temperature, weigh 12 g of alkali lignin and 0.6 g of solid NaOH, add them to 58 g of deionized water, stir for 30 minutes, and disperse at a high speed of 10000 rpm in a disperser for 30 minutes to obtain a uniformly dispersed aqueous solution of alkali lignin.

[0152] (2) Add the obtained aqueous solution of alkali lignin and 2.4 g of NaOH to a reactor equipped with a stirrer and a condenser, stir evenly and heat up to 50 °C, and keep the temperature constant for 90 min.

[0153] (3) Then raise the temperature of the system to the set temperature of 90 °C within 1 h, and slowly add 27 g of aqueous formaldehyde solution in three portions at intervals of 30 minutes with stirring, continue stirring, and carry out a sufficient reaction for 3 h;

[0154] (4) After the reaction is completed, quickly cool it to room temperature, adjust the pH to 2.0 with HCl, activate to precipitate the product, separate it at 8000 rpm / min, take the lower-layer precipitate, wash it 3 times with distilled water, and dry to obtain the product nano-hydroxymethylated lignin HML-3.

[0155] It was measured that the particle size of the original alkali lignin was 3 - 10 μm, and the average particle size of the modified HML-3 was 40 nm, and the hydroxymethyl content was 12.4 wt%.

[0156] Preparation Example 4

[0157] This preparation example is used to illustrate the preparation of the water-soluble phenolic resin crosslinking agent SPF-1.

[0158] In a three-necked flask equipped with a stirrer and a condenser, add 50 g of phenol. After heating and melting, add 18 g of NaOH solution (40 wt%). After maintaining the temperature at 50 °C for 30 min, slowly add 54 g of aqueous formaldehyde solution. After maintaining the temperature for 1.5 h, raise the temperature to 85 °C. Add 7.5 g of NaOH solution (40 wt%) and raise the temperature to 95 °C within 15 min. After maintaining the temperature for 30 min, lower the temperature to 85 °C. Then add 3.7 g of guaiacol, 11 g of aqueous formaldehyde solution and 55.8 g of water, raise the temperature to 90 °C, stop heating after reacting for 60 min, cool to 40 °C, and distill under reduced pressure to obtain the modified water-soluble phenolic resin SPF-1.

[0159] The free aldehyde, free phenol, and hydroxymethyl contents were determined according to GB / T 14074-2017 "Testing Methods for Adhesives and Resins for Wood Industry". It was measured that the free aldehyde content was 0.23%, the free phenol content was 0.41%, the hydroxymethyl content was 30.1%, and the solid content was 50.1%.

[0160] Preparation Example 5

[0161] This preparation example is used to illustrate the preparation of the water-soluble phenolic resin crosslinking agent SPF-2.

[0162] In a three-necked flask equipped with a stirrer and a condenser, add 40 g of phenol. After heating and melting, add 12 g of NaOH solution (40 wt%). After maintaining the temperature at 50 °C for 30 min, slowly add 60 g of aqueous formaldehyde solution. When the temperature is maintained for 1.5 h, raise the temperature to 80 °C. Add 10 g of NaOH solution (40 wt%) and continue to raise the temperature to 90 °C within 15 min. After maintaining the temperature for 30 min, lower the temperature to 80 °C. Then add 14.8 g of p-ethoxyphenol, 8 g of aqueous formaldehyde solution and 55.2 g of water, raise the temperature to 90 °C, stop heating after reacting for 60 min, cool to 40 °C, and distill under reduced pressure to obtain the modified water-soluble phenolic resin SPF-2.

[0163] The free formaldehyde, free phenol, and hydroxymethyl contents were determined according to GB / T 14074-2017 "Test Methods for Adhesives and Resins Used in the Wood Industry". After determination, the free formaldehyde content was 0.12%, the free phenol content was 0.35%, the hydroxymethyl content was 32.4%, and the solid content was 49.5%.

[0164] Preparation Example 6

[0165] This preparation example is used to illustrate the preparation of the water-soluble phenolic resin crosslinking agent SPF-3.

[0166] In a three-necked flask equipped with a stirrer and a condenser, 30 g of phenol and 10 g of o-cresol were added and heated to melt. Then, 12 g of NaOH solution (40 wt%) was added. After maintaining a constant temperature of 50 °C for 30 min, 15 g of acetaldehyde was slowly added dropwise. When the constant temperature reached 1.5 h, the temperature was raised to 80 °C. Then, 10 g of NaOH solution (40 wt%) was added and the temperature was further raised to 90 °C within 15 min. After maintaining a constant temperature of 30 min, the temperature was lowered to 80 °C. Then, 14.8 g of 2-methoxy-4-methylphenol, 5 g of acetaldehyde, and 103.2 g of water were added. The temperature was raised to 90 °C and the reaction was stopped after 60 min of heating. After cooling to 40 °C, the product was discharged by vacuum distillation to obtain the modified water-soluble phenolic resin SPF-3.

[0167] The free formaldehyde, free phenol, and hydroxymethyl contents were determined according to GB / T 14074-2017 "Test Methods for Adhesives and Resins Used in the Wood Industry". After determination, the free formaldehyde content was 0.68%, the free phenol content was 0.56%, the hydroxymethyl content was 20.1%, and the solid content was 48.9%.

[0168] Example 1

[0169] This example is used to illustrate the lignin-based high-strength temperature-resistant plugging and profile control material and its preparation method described in the present invention.

[0170] 1.2 g of acrylamide / sodium acrylate / AMPS copolymer (molecular weight 16 million, hydrolysis degree 18%) was added to 800 g of simulated brine. After stirring for 1 h, 60 g of nano-hydroxymethylated lignin HML-2 was added. After stirring until completely dissolved, 40 g of water-soluble phenolic resin crosslinking agent SPF-1 and 0.3 g of sodium thiosulfate were added. The total weight was made up to 1 kg with simulated brine and stirred evenly to obtain the lignin-based high-strength temperature-resistant plugging and profile control material.

[0171] The gel strength code method was used to record the gelation time of the high-temperature-resistant plugging and profile control material at 80 °C.

[0172] After the high-temperature-resistant plugging and profile control material gelled, it was maintained at 200 °C for 60 days, and then its dehydration rate and plugging rate were measured. The results are shown in Table 1.

[0173] Example 2

[0174] This example is used to illustrate the lignin-based high-strength temperature-resistant plugging and profile control material and its preparation method described in the present invention.

[0175] Add 0.8 g of acrylamide / sodium acrylate / acrylonitrile copolymer (molecular weight 15 million, hydrolysis degree 20%) to 800 g of simulated brine. After stirring for 0.5 h, add 80 g of nano-hydroxymethylated lignin HML-1 and stir until completely dissolved. Then add 45 g of water-soluble phenolic resin SPF-2 and 0.05 g of sodium bisulfite, and make up to a total weight of 1 kg with simulated brine. Stir evenly to obtain the lignin-based high-strength temperature-resistant plugging and profile control material.

[0176] Using the gel strength code method, record the gelation time of the lignin-based high-strength temperature-resistant plugging and profile control material at 90 °C.

[0177] After the lignin-based high-strength temperature-resistant plugging and profile control material gels, maintain it at 250 °C for 60 days, and then measure its dehydration rate and plugging rate. The results are shown in Table 1.

[0178] Example 3

[0179] This example is used to illustrate the lignin-based high-strength temperature-resistant plugging and profile control material and its preparation method described in the present invention.

[0180] Add 2 g of partially hydrolyzed polyacrylamide polymer (molecular weight 25 million, hydrolysis degree 15%) to 800 g of simulated brine. After stirring for 1 h, add 45 g of nano-hydroxymethylated lignin HML-3, and continue to stir until completely dissolved. Then add 30 g of water-soluble phenolic resin SPF-1 and 0.5 g of isoascorbic acid, and make up to a total weight of 1 kg with simulated brine. Stir evenly to obtain the lignin-based high-strength temperature-resistant plugging and profile control material.

[0181] Using the gel strength code method, record the gelation time of the lignin-based high-strength temperature-resistant plugging and profile control material at 65 °C.

[0182] After the lignin-based high-strength temperature-resistant plugging and profile control material gels, maintain it at 200 °C for 60 days, and then measure its dehydration rate and plugging rate. The results are shown in Table 1.

[0183] Example 4

[0184] This example is used to illustrate the lignin-based high-strength temperature-resistant plugging and profile control material and its preparation method described in the present invention.

[0185] Operate according to the method described in Example 1, except that the addition amounts of each component are different. Among them, 0.6 g of acrylamide / sodium acrylate / AMPS copolymer (molecular weight 30 million, hydrolysis degree 25%), 100 g of nano-hydroxymethylated lignin HML-1, 60 g of water-soluble phenolic resin crosslinking agent SPF-2, and 1 g of sodium bisulfite.

[0186] Adopt the gel strength code method to record the gelation time of the lignin-based high-strength temperature-resistant plugging and profile control material at 80 °C.

[0187] After the lignin-based high-strength temperature-resistant plugging and profile control material gels, keep it at 200 °C for 60 days, and then measure its dehydration rate and plugging rate. The results are shown in Table 1.

[0188] Example 5

[0189] This example is used to illustrate the lignin-based high-strength temperature-resistant plugging and profile control material and its preparation method described in the present invention.

[0190] Operate according to the method described in Example 1, except that the addition amounts of each component are different. Among them, 4 g of partially hydrolyzed polyacrylamide polymer (molecular weight 10 million, hydrolysis degree 10%), 35 g of nano-hydroxymethylated lignin HML-3, 20 g of water-soluble phenolic resin crosslinking agent SPF-1, and 0.02 g of sodium bisulfite.

[0191] Adopt the gel strength code method to record the gelation time of the lignin-based high-strength temperature-resistant plugging and profile control material at 80 °C.

[0192] After the lignin-based high-strength temperature-resistant plugging and profile control material gels, keep it at 200 °C for 60 days, and then measure its dehydration rate and plugging rate. The results are shown in Table 1.

[0193] Example 6

[0194] This example is used to illustrate the lignin-based high-strength temperature-resistant plugging and profile control material and its preparation method described in the present invention.

[0195] Operate according to the method described in Example 1, except that the preparation method of the nano-hydroxymethylated lignin includes: at room temperature, weigh 10 g of sulfate lignin and 0.6 g of NaOH, add them to 58.6 g of deionized water, and disperse them at a high speed of 5000 rpm in a disperser for 30 minutes to obtain a uniformly dispersed sulfate lignin aqueous solution.

[0196] (2) Add the obtained sulfate lignin aqueous solution and 2.4 g of NaOH to a reactor equipped with a stirrer and a condenser, stir evenly and heat up to 50 °C, and keep the temperature constant for 90 min.

[0197] (3) Then, heat the system to the set temperature of 90 °C within 1 h, and slowly add 21 g of aqueous formaldehyde solution in three portions at intervals of 30 minutes with stirring. Continue stirring for sufficient reaction for 3 h.

[0198] (4) After the reaction is completed, quickly cool to room temperature, adjust the pH to 2.0, activate to precipitate the product, separate at 8000 rpm / min, take the lower-layer precipitate, wash it 3 times with distilled water, and dry to obtain the product nano-hydroxymethylated lignin.

[0199] The average particle size of the obtained nano-hydroxymethylated lignin is 400 nm, and the hydroxymethyl content is 8.6 wt%.

[0200] Adopt the gel strength code method to record the gelation time of the lignin-based high-strength temperature-resistant plugging material at 80 °C.

[0201] After the lignin-based high-strength temperature-resistant plugging material gels, maintain it at 200 °C for 60 days, and then measure its dehydration rate and plugging rate. The results are shown in Table 1.

[0202] Example 7

[0203] This example is used to illustrate the lignin-based high-strength temperature-resistant plugging material and its preparation method according to the present invention.

[0204] Operate according to the method described in Example 1, except that 52 g of water-soluble phenolic resin (purchased from Dongying Fangli Chemical Technology Co., Ltd., Shandong, pH > 11, solid content 38.5%) is used to replace SPF-1 in Example 1.

[0205] Adopt the gel strength code method to record the gelation time of the lignin-based high-strength temperature-resistant plugging material at 80 °C.

[0206] After the lignin-based high-strength temperature-resistant plugging material gels, maintain it at 200 °C for 60 days, and then measure its dehydration rate and plugging rate. The results are shown in Table 1.

[0207] Example 8

[0208] This example is used to illustrate the lignin-based high-strength temperature-resistant plugging material and its preparation method according to the present invention.

[0209] Operate according to the method described in Example 7, except that the dosage of water-soluble phenolic resin SPF-1 is 60 g.

[0210] Adopt the gel strength code method to record the gelation time of the lignin-based high-strength temperature-resistant plugging material at 80 °C.

[0211] After the lignin-based high-strength temperature-resistant plugging and profile control material gels, it is maintained at 200 °C for 60 days, and then its dehydration rate and plugging rate are measured. The results are shown in Table 1.

[0212] Example 9

[0213] This example is used to illustrate the lignin-based high-strength temperature-resistant plugging and profile control material and its preparation method according to the present invention.

[0214] Operate according to the method described in Example 1, except that the SPF-3 resin prepared in Preparation Example 6 with the same mass is used to replace the SPF-1 resin in Example 1.

[0215] Adopt the gel strength code method to record the gelation time of the lignin-based high-strength temperature-resistant plugging and profile control material at 80 °C.

[0216] After the lignin-based high-strength temperature-resistant plugging and profile control material gels, it is maintained at 200 °C for 60 days, and then its dehydration rate and plugging rate are measured. The results are shown in Table 1.

[0217] Comparative Example 1

[0218] This comparative example is used to illustrate the reference lignin-based high-strength temperature-resistant plugging and profile control material and its preparation method.

[0219] Conduct the test according to the method of Example 1, except that the nano-hydroxymethylated lignin HML-1 is replaced with unmodified sodium lignosulfonate.

[0220] Adopt the gel strength code method to record the gelation time of the lignin-based high-strength temperature-resistant plugging and profile control material at 80 °C.

[0221] After the lignin-based high-strength temperature-resistant plugging and profile control material gels, it is maintained at 200 °C for 60 days, and then its dehydration rate and plugging rate are measured. The results are shown in Table 1.

[0222] Comparative Example 2

[0223] This comparative example is used to illustrate the reference lignin-based high-strength temperature-resistant plugging and profile control material and its preparation method.

[0224] Conduct the test according to the method of Example 1, except that the nano-hydroxymethylated lignin HML-1 is replaced with another hydroxymethylated lignin, and its preparation method includes: adding 5 g of sodium lignosulfonate to 20 g of deionized water, adjusting the pH to 11 with NaOH, heating to 90 °C, and then slowly dropping 4 g of formaldehyde aqueous solution, and reacting at a constant temperature for 5 h. After the reaction is completed, it is cooled to room temperature to obtain a crude product, which is purified with an ion exchange resin and then dried to obtain hydroxymethylated lignosulfonate. The average particle size of the obtained hydroxymethylated lignin is 2.5 μm, and the hydroxymethyl content is 8.2% by weight.

[0225] The gel strength code method was adopted to record the gelation time of the lignin-based high-strength temperature-resistant profile control and water plugging material at 80 °C.

[0226] After the lignin-based high-strength temperature-resistant profile control and water plugging material gelled, it was maintained at 200 °C for 60 days, and then its dehydration rate and plugging rate were measured. The results are shown in Table 1.

[0227] Table 1

[0228] Number Gelation time / h Dehydration rate / % Blocking rate / % Strength / MPa Example 1 40 1.2 99.89 0.086 Example 2 32 3.5 99.68 0.078 Example 3 128 6.7 98.71 0.066 Example 4 35 2.8 99.76 0.080 Example 5 32 6.9 98.70 0.065 Example 6 54 7.0 98.73 0.064 Example 7 50 5.6 99.56 0.072 Example 8 48 5.4 99.57 0.073 Example 9 46 4.9 99.61 0.074 Comparative Example 1 86 11.3 90.17 0.045 Comparative Example 2 70 10.2 91.35 0.049

[0229] From the above results, it can be seen that compared with the comparative example, the lignin-based high-strength temperature-resistant profile control and water plugging material prepared in the embodiment of the present invention has higher thermal stability and plugging rate at 200-250 °C, and has significantly better effects on plugging edge water and steam channeling in steam stimulation high water cut wells.

[0230] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited thereto. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention, including any other suitable combination of each technical feature. These simple modifications and combinations should also be regarded as the content disclosed by the present invention and fall within the protection scope of the present invention.

Claims

1. A lignin-based plugging agent raw material composition, characterized in that The lignin-based plugging agent raw material composition comprises: nano-hydroxymethylated lignin, an anionic acrylamide polymer, a water-soluble phenolic resin crosslinking agent, and an oxygen scavenger; Based on the total weight of the lignin-based plugging agent raw material composition, the content of the nano-hydroxymethylated lignin is 3.5-10% by weight, the content of the anionic acrylamide polymer is 0.06-0.4% by weight, the content of the water-soluble phenolic resin crosslinking agent is 2-6% by weight, and the content of the oxygen scavenger is 0.002-0.1% by weight; The average particle size of the nano-hydroxymethylated lignin is 20-100 nm; The hydroxymethyl content in the nano-hydroxymethylated lignin is 8-13% by weight; The anionic acrylamide polymer is selected from at least one of partially hydrolyzed polyacrylamide, acrylamide / acrylic acid (sodium) / N-vinylpyrrolidone copolymer, acrylamide / acrylic acid (sodium) / AMPS (sodium) copolymer, acrylamide / AMPS (sodium) copolymer, and acrylamide / acrylic acid (sodium) / acrylonitrile copolymer.

2. The lignin-based plugging agent raw material composition according to claim 1, wherein, The lignin-based plugging agent raw material composition further contains a solvent; Based on the total weight of the lignin-based plugging agent raw material composition, the content of the solvent is 83.5-94.438% by weight.

3. The lignin-based plugging agent raw material composition according to claim 1, wherein, Based on the total weight of the lignin-based plugging agent raw material composition, the content of the nano-hydroxymethylated lignin is 4.5-8% by weight, the content of the anionic acrylamide polymer is 0.08-0.2% by weight, the content of the water-soluble phenolic resin crosslinking agent is 3-4.5% by weight, and the content of the oxygen scavenger is 0.005-0.05% by weight.

4. The lignin-based plugging agent raw material composition according to claim 2, wherein, The solvent is water; Based on the total weight of the lignin-based plugging agent raw material composition, the content of the solvent is 87.25-92.415% by weight.

5. The lignin-based plugging agent raw material composition according to claim 1, wherein, The preparation method of the nano-hydroxymethylated lignin includes: under alkaline conditions, contacting a lignin raw material with an aldehyde modifier for reaction to obtain nano-hydroxymethylated lignin.

6. The lignin-based plugging agent raw material composition according to claim 5, wherein, The lignin raw material is selected from at least one of alkali lignin, enzymatically hydrolyzed lignin, chlorinated lignin, steam-exploded lignin, lignin sulfonate, and sulfur lignin.

7. The lignin-based plugging agent raw material composition according to claim 5, wherein, The aldehyde modifier is selected from formaldehyde and / or paraformaldehyde.

8. The lignin-based plugging agent raw material composition according to claim 5, wherein, The mass ratio of the aldehyde modifier to the lignin raw material is 0.1-0.9:

1.

9. The lignin-based plugging agent raw material composition according to claim 5, wherein, The conditions of the contacting reaction include: temperature of 70-90 °C and time of 2-6 h.

10. The lignin-based plugging agent raw material composition according to claim 1, wherein, The viscosity-average molecular weight of the anionic acrylamide polymer is 10 million - 30 million.

11. The lignin-based plugging agent raw material composition according to claim 1 or 10, wherein, The viscosity-average molecular weight of the anionic acrylamide polymer is 15 million - 25 million.

12. The lignin-based plugging agent raw material composition according to claim 1, wherein, The hydrolysis degree of the anionic acrylamide polymer is 10-25%.

13. The lignin-based plugging agent raw material composition according to claim 1, wherein, The hydrolysis degree of the anionic acrylamide polymer is 15-20%.

14. The lignin-based plugging agent raw material composition according to claim 1, wherein, The water-soluble phenolic resin crosslinking agent is a water-soluble prepolymer of a phenolic raw material and an aldehyde raw material.

15. The lignin-based plugging agent raw material composition according to claim 14, wherein, The phenolic raw material includes a first phenolic raw material and a second phenolic raw material; The first phenolic raw material is at least one of phenol, cresol, hydroquinone, catechol, and resorcinol; The second phenolic raw material has the structure shown in formula (1), wherein R1 and R2 are each independently selected from H or an alkoxy group, and R3 is selected from one of H, methyl, ethyl, methoxy, and ethoxy; Formula (1).

16. The lignin-based plugging agent raw material composition according to claim 15, wherein, The first phenolic raw material is phenol.

17. The lignin-based plugging agent raw material composition according to claim 15, wherein, The alkoxy group is selected from one of methoxy, ethoxy, and propoxy.

18. The lignin-based plugging agent raw material composition according to claim 14, wherein, The aldehyde raw material is at least one of formaldehyde, acetaldehyde, paraformaldehyde, and furfural.

19. The lignin-based plugging agent raw material composition according to claim 18, wherein, The aldehyde raw material is formaldehyde.

20. The lignin-based plugging agent raw material composition according to claim 14, wherein, The molar ratio of the phenolic raw material to the aldehyde raw material is 1:1.2 - 2.

21. The lignin-based plugging agent raw material composition according to claim 1, wherein, The deoxidizer is at least one of sodium thiosulfate, sodium sulfite, sodium bisulfite, sodium dithionite, isoascorbic acid, and thiourea.

22. A preparation method of a lignin-based profile control material, characterized in that, The method includes: In the presence of a solvent, mixing nano - hydroxymethylated lignin and an anionic acrylamide - based polymer, and then mixing with a water - soluble phenolic resin cross - linker and a deoxidizer to obtain the lignin - based profile control material; Based on the total weight of the lignin - based profile control material, the dosage of the nano - hydroxymethylated lignin is 3.5 - 10% by weight, the dosage of the anionic acrylamide - based polymer is 0.06 - 0.4% by weight, the dosage of the water - soluble phenolic resin cross - linker is 2 - 6% by weight, and the dosage of the deoxidizer is 0.002 - 0.1% by weight; The average particle size of the nano - hydroxymethylated lignin is 20 - 100 nm, and the hydroxymethyl content is 8 - 13% by weight; The anionic acrylamide - based polymer is selected from at least one of partially hydrolyzed polyacrylamide, acrylamide / sodium acrylate / N - vinylpyrrolidone copolymer, acrylamide / sodium acrylate / AMPS (sodium) copolymer, acrylamide / AMPS (sodium) copolymer, and acrylamide / sodium acrylate / acrylonitrile copolymer.

23. The method according to claim 22, wherein, Based on the total weight of the lignin - based profile control material, the dosage of the solvent is 83.5 - 94.438% by weight.

24. The method according to claim 22, wherein, Based on the total weight of the lignin - based profile control material, the dosage of the nano - hydroxymethylated lignin is 4.5 - 8% by weight, the dosage of the anionic acrylamide - based polymer is 0.08 - 0.2% by weight, the dosage of the water - soluble phenolic resin cross - linker is 3 - 4.5% by weight, and the dosage of the deoxidizer is 0.005 - 0.05% by weight.

25. The method according to claim 22, wherein, Based on the total weight of the lignin - based profile control material, the dosage of the solvent is 87.25 - 92.415% by weight.

26. The method according to claim 22, wherein, The water - soluble phenolic resin cross - linker is a water - soluble prepolymer of a phenolic raw material and an aldehyde raw material; The deoxidizer is at least one of sodium thiosulfate, sodium sulfite, sodium bisulfite, sodium dithionite, isoascorbic acid, and thiourea; and / or The solvent is water.

27. The lignin - based profile control material prepared by the method according to any one of claims 22 - 26.

28. The application of the lignin - based plugging agent raw material composition according to any one of claims 1 - 21 or the lignin - based profile control material according to claim 27 in oil reservoir exploitation.

29. The application of the lignin - based plugging agent raw material composition according to any one of claims 1 - 21 or the lignin - based profile control material according to claim 27 in the thermal recovery of heavy oil by steam stimulation.

30. A method for oil reservoir exploitation, characterized in that, The method includes: injecting the lignin-based profile control material described in claim 27 into a formation, so that the lignin-based profile control material crosslinks in situ in the formation to form a gel.

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