CN117089011A - Air wetting reversal agent suitable for compact sandstone surface, and preparation method and application thereof - Google Patents

Air wetting reversal agent suitable for compact sandstone surface, and preparation method and application thereof Download PDF

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CN117089011A
CN117089011A CN202311031208.5A CN202311031208A CN117089011A CN 117089011 A CN117089011 A CN 117089011A CN 202311031208 A CN202311031208 A CN 202311031208A CN 117089011 A CN117089011 A CN 117089011A
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solution
reversal agent
methacrylate
wetting reversal
gas
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CN117089011B (en
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赖小娟
卢丽娟
刘贵茹
王磊
刘璇
高进浩
薛瑜瑜
马芹芹
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Shaanxi University of Science and Technology
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    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
    • C08F220/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical or a salt, anhydride ester, amide, imide or nitrile thereof
    • C08F220/02—Monocarboxylic acids having less than ten carbon atoms; Derivatives thereof
    • C08F220/10—Esters
    • C08F220/12—Esters of monohydric alcohols or phenols
    • C08F220/14—Methyl esters, e.g. methyl (meth)acrylate
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
    • C08F2/00—Processes of polymerisation
    • C08F2/12—Polymerisation in non-solvents
    • C08F2/16—Aqueous medium
    • C08F2/22—Emulsion polymerisation
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
    • C08F220/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical or a salt, anhydride ester, amide, imide or nitrile thereof
    • C08F220/02—Monocarboxylic acids having less than ten carbon atoms; Derivatives thereof
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    • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
    • C08F220/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical or a salt, anhydride ester, amide, imide or nitrile thereof
    • C08F220/02—Monocarboxylic acids having less than ten carbon atoms; Derivatives thereof
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    • C08F220/32—Esters containing oxygen in addition to the carboxy oxygen containing epoxy radicals
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    • C08F220/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical or a salt, anhydride ester, amide, imide or nitrile thereof
    • C08F220/02—Monocarboxylic acids having less than ten carbon atoms; Derivatives thereof
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    • C09K8/00—Compositions for drilling of boreholes or wells; Compositions for treating boreholes or wells, e.g. for completion or for remedial operations
    • C09K8/58—Compositions for enhanced recovery methods for obtaining hydrocarbons, i.e. for improving the mobility of the oil, e.g. displacing fluids
    • C09K8/588—Compositions for enhanced recovery methods for obtaining hydrocarbons, i.e. for improving the mobility of the oil, e.g. displacing fluids characterised by the use of specific polymers

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Abstract

The invention relates to the technical field of oil and gas field development and enhanced oil recovery, in particular to a dense sandstone surface gas wetting reversal agent and a preparation method and application thereof. The method comprises the following steps: (1) Weighing dispersant and water to prepare dispersant solution with concentration of 3-5%; (2) Uniformly mixing 1.8-2.0 parts of methacrylate monomers, 0.1 part of silane coupling agent and 0.5-2.0 parts of fluorine-containing monomers to prepare a solution B; (3) Weighing 0.02-0.04 part of initiator, and dissolving to obtain solution C; (4) And (3) carrying out water bath, taking 1/3 of the solution B, stirring for 3-5min, adding 1/3 of the solution C to obtain a solution D, slowly dropwise adding the rest 2/3 of the solution B and the solution C into the solution D, and reacting for 2-5h to obtain the air wetting reversal agent. The invention avoids the adverse effects of surface property, water resistance, film forming property, pollution to stratum and the like caused by the existence of the emulsifier in the application process; meanwhile, the fluorine-containing polymer has good dispersibility in water, and is beneficial to on-site liquid preparation and use; the recovery ratio can be effectively improved; the preparation method is simple; the operability is strong.

Description

Air wetting reversal agent suitable for compact sandstone surface, and preparation method and application thereof
Technical Field
The invention relates to the technical field of oil and gas field development and enhanced oil recovery, in particular to a dense sandstone surface gas wetting reversal agent and a preparation method and application thereof.
Background
In recent years, along with the deep exploration and development of gas fields, the exploitation of complex oil and gas resources such as hypotonic sand, tight sandstone and the like is gradually increased. In the development process of oil and gas resources, a large amount of water-based working solution is often required to be injected, and due to the hydrophilicity and sealing property of rocks, the capillary effect is obvious, stratum water, injected water and condensate water are easy to stay in a runner, so that the effective permeability of gas phase is reduced, and water lock phenomenon is caused by easy water retention in a reservoir.
The occurrence of water lock phenomenon can lead to the rapid decrease of the production energy consumption and the oil and gas recovery ratio. Changing the free energy of the solid surface is a critical step in changing reservoir wettability from hydrophilic to hydrophobic. The surface free energy can be changed in two ways. The most straightforward approach is to vary the roughness of the reservoir surface, the greater the surface roughness the higher the hydrophobic state energy barrier between the water and the solid surface, the more stable the hydrophobic state. For example, if the surface is hydrophobic, its hydrophobicity will also increase as the surface roughness increases. Another approach is to alter the chemical structure of the surface material by altering the reservoir wettability with a wetting reversal agent, most of which are surfactant materials that have good dispersibility but lack erosion resistance and adsorption capacity in the formation, and therefore are not ideal.
In recent years, the hydrophobic effect of polymeric materials as a wetting reversal agent has been improved. The fluorine-containing polymer has a very low surface free energy because of the small atomic radius of fluorine atoms and the large bond energy of C-F bonds in the structure. Therefore, fluoropolymers are widely used for preparing interface materials having anti-sticking, anti-friction, oil-water-gas separation, etc., and for example, fluoropolymers may be prepared as emulsions to improve their dispersibility in aqueous systems. As a reversing agent, the fluorine-containing polymer emulsion is injected into the stratum in the form of polymer fluid, after adsorption, the formation channel and wettability of a reservoir layer can be changed in the surface of the rock, the free energy of the surface of the rock core can be reduced, the surface of the rock core is converted from hydrophilicity to hydrophobicity, the wettability is reversed, the water lock injury is prevented, and an effective thought is provided for improving the recovery ratio of the oil reservoir. However, the conventional method for preparing a fluorine-containing polymer has the following problems: 1. the preparation cost is high, 2, the prepared product is volatile due to the use of a volatile organic solvent in the synthesis process, so that the environment is not protected, 3, the fluorine-containing polymer has poor dispersibility in water, and the fluorine-containing polymer has poor compatibility with other working fluids after being injected into a stratum, so that the recovery ratio is low, and the application of the fluorine-containing polymer in oil-gas field development is hindered.
In conclusion, the preparation method of the dense sandstone surface air wetting reversal agent is continuously optimized, and the method becomes an important research direction for scientific researchers in the field.
Disclosure of Invention
The invention provides a dense sandstone surface gas wetting reversal agent, and a preparation method and application thereof, and aims to solve the problems of poor dispersibility and poor wetting change capability of the wetting reversal agent in the prior art.
In order to achieve the above purpose, the present invention provides the following technical solutions: the preparation method of the gas wetting reversal agent suitable for the surface of the compact sandstone comprises the following steps:
(1) Weighing dispersant and water to prepare dispersant solution with concentration of 3-5%, taking 5-7 parts of the dispersant solution, sealing, placing the dispersant solution in a constant-temperature water bath at 60 ℃ and stirring the dispersant solution by a constant-speed stirrer at 500 r/min;
(2) Uniformly mixing 1.8-2.0 parts of methacrylate monomers, 0.1 part of silane coupling agent and 0.5-2.0 parts of fluorine-containing monomers to prepare a solution B;
(3) Weighing 0.02-0.04 part of initiator, and dissolving 20mL of water to obtain solution C;
(4) When the temperature of the water bath is raised to 80-90 ℃, 1/3 solution B is taken and stirred for 3-5min, 1/3 solution C is added to obtain solution D, the system is blue, stirring is continued for 10-15min, the rest 2/3 solution B and 2/3 solution C are slowly dripped into the solution D, the dripping is completed in 2-3 hours, the temperature is raised to 85-90 ℃, the heat preservation reaction is continued for 2-5h, the emulsion is cooled to room temperature, and the air wetting reversal agent is obtained after discharging.
Further, the dispersing agent is one or a mixture of two or more of acrylonitrile modified starch, ethanol, glycerol and polyvinyl alcohol in any proportion.
Further, the methacrylate monomer is one or a mixture of two or more than two of hexyl methacrylate, n-octyl methacrylate, glycerol methacrylate, methyl methacrylate and butyl acrylate in any proportion.
Further, the fluorine-containing monomer is trifluoroethyl acrylate, hexafluorobutyl acrylate, dodecafluoroheptyl acrylate, perfluorooctyl ethyl acrylate, nineteen fluoro acrylate, perfluorooctyl (N-methyl-N-ethyl acrylate) sulfonamide, perfluorooctyl (N-ethyl-N-ethyl acrylate) sulfonamide, trifluoroethyl methacrylate, hexafluorobutyl methacrylate, dodecafluoroheptyl methacrylate, nineteen fluoro methacrylate, perfluorooctyl (N-methyl-N-ethyl methacrylate) sulfonamide or perfluoroalkyl ethyl acrylate.
Further, the silane coupling agent is one or two of gamma-aminopropyl triethoxysilane (KH-550), gamma-glycidoxypropyl trimethoxysilane (KH-560), gamma- (methacryloyloxy) propyl trimethoxysilane (KH-570), N- (beta-aminoethyl) -gamma-aminopropyl trimethyl (ethoxy) silane (KH-792) and N-beta- (aminoethyl) -gamma-aminopropyl methyl dimethoxy silane (DL-602) in any proportion.
Further, the initiator is one or a mixture of two of potassium persulfate, ammonium persulfate, azodiisobutyronitrile and azodiisobutyl prochloraz hydrochloride in any proportion.
Furthermore, the air wetting reversal agent is suitable for the surface of compact sandstone.
Further, the application of the dense sandstone surface gas wetting reversal agent in improving the yield of a dense sandstone gas well is that fracturing fluid or water is added into the dense sandstone surface gas wetting reversal agent to prepare a reversal agent solution with the mass concentration of 0.5% -2%, the reversal agent solution is pumped into a dense sandstone reservoir until the surface of the dense sandstone reservoir is fully soaked in the reversal agent solution, wherein the contact treatment temperature of the wetting reversal agent solution and the surface of the dense sandstone reservoir is 60 ℃ -130 ℃, and the soaking time is 4-8 hours.
Further, the fracturing fluid is more than one of slickwater fracturing fluid, guar gum fracturing fluid and foam fracturing fluid. Compared with the prior art, the invention has the advantages that:
(1) The present invention alters wettability by reducing surface free energy. Emulsion particles with functional groups and good dispersibility are prepared by adopting a soap-free emulsion polymerization method, the emulsion prepared by the method has the advantages of difficult demulsification and stable storage, and the surface of the prepared emulsion particles is clean, so that adverse effects on surface performance, water resistance, film forming property, pollution to stratum and the like caused by the existence of an emulsifier in the application process are avoided; meanwhile, the fluorine-containing polymer has good dispersibility in water, and is beneficial to on-site liquid preparation and use.
(2) According to the invention, an organosilicon functional group with amphiphobic property is introduced on the molecular structure of a conventional fluorine-containing wetting reversal agent, the gas wetting reversal agent can be solidified on the surface of a core matrix to form a hydrophobic and oleophobic membrane, and the wettability of the rock surface is changed by utilizing the synergistic effect of the organosilicon, so that the wetting reversal is realized. The gas wetting reversal agent is solidified on the surface of the base material through dipping and drying, has high compressive strength and high hydrophobicity, further prevents water lock caused by liquid retention in near-entering zones and cracks, achieves the purposes of rapidly discharging liquid and improving the yield of a tight sandstone gas well by changing the wettability of a low-permeability reservoir, and can effectively improve the recovery ratio.
(3) The preparation method is simple, and the soap-free emulsion polymerization method is adopted, so that the operability is high. In the synthesis process, methacrylate monomers are used as similar solvents to replace volatile organic solvents, so that the polymer is a nontoxic and environment-friendly polymer material and is friendly to operators.
Description of the drawings:
FIG. 1 is a graph of the self-priming height variation test of different mass fraction gas-wet reverser capillaries;
FIG. 2 is a graph of particle size measurements of a gas-wet reversal agent;
FIG. 3 is a graph of the surface tension change of different mass fraction gas wetting reversal agents;
FIG. 4 is a graph of free energy of a different mass fraction gas-wetting reversal agent surface as a function of contact angle;
FIG. 5 is a graph of contact angles of different mass fractions of a gas-wet reversal agent with water;
FIG. 6 shows the gas displacement rates of different mass fractions of the gas-wet reversal agent.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention and the accompanying drawings.
Example 1
(1) Weighing 3g of acrylonitrile modified starch and water to prepare a dispersing agent solution with the concentration of 3%, taking 5 parts of dispersing agent solution into a 250mL three-neck flask to obtain solution A, sealing, placing the solution A in a 60 ℃ constant-temperature water bath, and stirring the solution A by a constant-speed stirrer of 500 r/min;
(2) 1.8 parts of methyl methacrylate, 0.1 part of KH-570 and 0.5 part of perfluoroalkyl ethyl acrylate are uniformly mixed to prepare a solution B;
(3) Weighing 0.02 part of azodiisobutyronitrile in a beaker, and dissolving 20mL of water to obtain a solution C;
(4) When the water bath temperature is raised to 80 ℃, taking 1/3 solution B, continuously stirring for 3min in a three-neck flask, adding 1/3 solution C to obtain solution D, continuously stirring for 10min, slowly dropwise adding the rest 2/3 solution B and 2/3 solution C (dropwise adding the rest 2/3 solution B and the rest 2/3 solution C in the solution D by using a microinjector for about 2-3 hours), heating to 85 ℃, continuously preserving heat for 2h, cooling the emulsion to room temperature, discharging, and obtaining the air wetting reversal agent.
Example 2
(1) Weighing 4g of polyvinyl alcohol and water to prepare a dispersing agent solution with the concentration of 4%, taking 6 parts of dispersing agent solution into a 250mL three-neck flask to obtain solution A, sealing, placing the solution A into a constant-temperature water bath at 60 ℃ and stirring the solution A by a constant-speed stirrer at 500 r/min;
(2) Solution B was prepared by uniformly mixing 0.9 part of methyl methacrylate, 0.9 part of butyl acrylate mixed monomer, 0.1 part of KH-550 and 1.0 part of hexafluorobutyl acrylate;
(3) Weighing 0.03 part of potassium persulfate in a beaker, and taking 20mL of water for dissolution to obtain a solution C;
(4) When the water bath temperature is raised to 80 ℃, taking 1/3 solution B, continuously stirring for 3min in a three-neck flask, adding 1/3 solution C to obtain solution D, continuously stirring for 10min, slowly dropwise adding the rest 2/3 solution B and 2/3 solution C (dropwise adding the rest 2/3 solution B and the rest 2/3 solution C in the solution D by using a microinjector for about 2-3 hours), heating to 85 ℃, continuously preserving heat for reaction for 3h, cooling the emulsion to room temperature, and discharging to obtain the air-wetting reversal agent.
Example 3
(1) Weighing 3g of ethanol, 2g of glycerol and water to prepare a dispersing agent solution with the concentration of 5%, taking 7 parts of dispersing agent solution into a 250mL three-neck flask to obtain solution A, sealing, placing into a constant-temperature water bath at 60 ℃ and stirring at a constant-speed stirrer of 500 r/min;
(2) Uniformly mixing 2.0 parts of hexyl methacrylate, N-octyl methacrylate, glyceride methacrylate mixed monomers (the mass ratio is 2:2:1), 0.1 part of KH-560 and 2.0 parts of perfluorooctyl (N-methyl-N-ethyl acrylate) sulfonamide to prepare a solution B;
(3) Weighing 0.04 part of azodiisobutyl prochloraz hydrochloride in a beaker, and taking 20mL of water for dissolution to obtain a solution C;
(4) When the water bath temperature is raised to 80 ℃, taking 1/3 solution B, continuously stirring for 3min in a three-neck flask, adding 1/3 solution C to obtain solution D, continuously stirring for 10min, slowly dropwise adding the rest 2/3 solution B and 2/3 solution C (dropwise adding the rest 2/3 solution B and the rest 2/3 solution C in the solution D by using a microinjector for about 2-3 hours), heating to 85 ℃, continuously preserving heat for reacting for 5h, cooling the emulsion to room temperature, discharging, and obtaining the air wetting reversal agent.
Example 4
(1) Weighing 3g of glycerol and water to prepare a dispersing agent solution with the concentration of 3%, taking 5 parts of dispersing agent solution into a 250mL three-neck flask to obtain a solution A, sealing, placing the solution A into a constant-temperature water bath at 60 ℃ and stirring the solution A by a constant-speed stirrer at 500 r/min;
(2) Uniformly mixing 2.0 parts of glycerol methacrylate, 0.1 part of KH-792 and 1.5 parts of trifluoroethyl methacrylate to prepare a solution B;
(3) Weighing 0.02 part of ammonium persulfate in a beaker, and taking 20mL of water for dissolution to obtain a solution C;
(4) When the water bath temperature is raised to 80 ℃, taking 1/3 solution B, continuously stirring for 3min in a three-neck flask, adding 1/3 solution C to obtain solution D, continuously stirring for 10min, slowly dropwise adding the rest 2/3 solution B and 2/3 solution C (dropwise adding the rest 2/3 solution B and the rest 2/3 solution C in the solution D by using a microinjector for about 2-3 hours), heating to 85 ℃, continuously preserving heat for reacting for 4h, cooling the emulsion to room temperature, and discharging to obtain the air wetting reversal agent.
Example 5
(1) Weighing 2g of polyvinyl alcohol and 1g of ethanol to prepare a dispersing agent solution with the concentration of 3% with water, taking 6 parts of dispersing agent solution into a 250mL three-neck flask to obtain a solution A, sealing, placing the solution A into a 60 ℃ constant-temperature water bath, and stirring the solution A by a constant-speed stirrer of 500 r/min;
(2) 1.8 parts of hexyl methacrylate, 0.1 part of DL-602 and 2.0 parts of dodecafluoroheptyl methacrylate are uniformly mixed to prepare a solution B;
(3) Weighing 0.01 part of potassium persulfate and 0.01 part of azobisisobutyronitrile into a beaker, and dissolving 20mL of water to obtain a solution C;
(4) When the water bath temperature is raised to 80 ℃, taking 1/3 solution B, continuously stirring for 3min in a three-neck flask, adding 1/3 solution C to obtain solution D, continuously stirring for 10min, slowly dropwise adding the rest 2/3 solution B and 2/3 solution C (dropwise adding the rest 2/3 solution B and the rest 2/3 solution C in the solution D by using a microinjector for about 2-3 hours), heating to 85 ℃, continuously preserving heat for reacting for 4h, cooling the emulsion to room temperature, and discharging to obtain the air wetting reversal agent.
Example 6
(1) Weighing 3g of polyvinyl alcohol and water to prepare a dispersing agent solution with the concentration of 3%, taking 5 parts of dispersing agent solution into a 250mL three-neck flask to obtain solution A, sealing, placing the solution A into a constant-temperature water bath at 60 ℃ and stirring the solution A by a constant-speed stirrer at 500 r/min;
(2) 1.8 parts of methyl methacrylate, 0.1 part of KH-570 and 2.0 parts of dodecafluoroheptyl methacrylate are uniformly mixed to prepare a solution B;
(3) Weighing 0.02 part of azodiisobutyl prochloraz hydrochloride in a beaker, and taking 20mL of water for dissolution to obtain a solution C;
(4) When the water bath temperature is raised to 80 ℃, taking 1/3 solution B, continuously stirring for 3min in a three-neck flask, adding 1/3 solution C to obtain solution D, continuously stirring for 10min, slowly dropwise adding the rest 2/3 solution B and 2/3 solution C (dropwise adding the rest 2/3 solution B and the rest 2/3 solution C in the solution D by using a microinjector for about 2-3 hours), heating to 85 ℃, continuously preserving heat for reacting for 5h, cooling the emulsion to room temperature, discharging, and obtaining the air wetting reversal agent.
Taking example 6 as the best example, performance test was performed on it:
(1) Emulsion stability test
(2) Capillary self-priming height test
Untreated hard neutral glass sample-application capillary with an inner diameter of 0.3mm and a tube length of 100mm is used, the wetting reversal agents with different mass fractions are measured and prepared, the capillary is vertically inserted into the solution, the self-priming height of the solution in the capillary is recorded, the self-priming liquid level height reduction rate of the capillary is calculated, and clear water is used as a control group.
As the mass fraction of the gas-wetting reversal agent increases, the self-priming level of the capillary tube decreases and the level height reduction rate increases. The fluorine-containing polyacrylate is characterized in that the fluorine-containing polyacrylate is coated on the surface of a substrate, the fluoroalkyl groups are gathered and self-configuration is formed to form a hydrophobic surface, the fluorine component is greatly migrated and concentrated on the surface of the film along with the increase of the mass fraction of the gas wetting reversal agent, the contact angle is increased by the increase of the hydrophobic property, the vertical liquid level in the capillary is reduced to an upward force (F), even at the top end of the capillary, the liquid level is changed from a concave liquid level to a convex liquid level, at the moment, F is a negative value, no effective lifting force can be provided at all, so that the self-absorption height of the capillary is reduced, and the reversal of the wettability of the reservoir can reduce dialysis caused by capillary force. Referring to fig. 1, when the mass fraction of the air-wetting reversal agent reaches 2.0wt%, the self-priming liquid level of the capillary tube is reduced to 30mm, the self-priming liquid level reduction rate of the capillary tube is 28.57%, and the wettability of the core is changed from hydrophilicity to hydrophobicity by the improvement of the self-priming liquid level reduction rate of the capillary tube.
(3) Particle size test
The air-wetting inverter was diluted to 0.5wt% and the particle size distribution of the emulsion was determined using a Master-sizer2000 malvern laser particle size analyzer. Referring to FIG. 2, the average particle diameter of the air-wetting reversal agent of the present invention was 89.7nm.
(4) Surface tension test: referring to FIG. 3, when the mass fraction of the air-wetting reversal agent was 2.0wt%, the surface tension was reduced to 22.68mN/m; it can be seen that the surface tension gradually decreases as the mass fraction of the gas-wetting reversal agent increases. This is because the fluoro-substituted alkyl groups in the polymer structure can lower the surface free energy of the interface, resulting in a decrease in surface tension.
(5) Contact angle and surface free energy:
the free energy and contact angle of the solid surface are the main basis for judging the wettability change. Hydrophilic when the surface contact angle is less than 90 °, and hydrophobic when greater than 90 °. According to the Young's equation, the surface free energy of the core is calculated by using a Bei Teluo rule, and the calculation formula is shown in (1):
wherein:
θ -contact angle of core with water, °;
γ lv -gas-liquid interfacial surface free energy, mN/m;
γ sv free energy at the gas-solid interface, mN/m.
As shown in FIG. 4, when the mass fraction of the air-wetting reversal agent is 2.0wt%, the surface free energy of the core is reduced from 73.2mN/m to 8.7 mN/m; as the mass fraction of the fluorine-containing emulsion increases, the contact angle of the core with water increases, and the surface free energy of the core decreases. As can be seen from fig. 5, when the mass fraction of the gas-wetting reversal agent is 2.0 and wt%, the contact angle between the core surface and water after film formation is increased to 125.1 °, and when the gas-wetting reversal agent amounts to 0%, 0.5%, 1.0%, 1.5% and 2.0 and wt%, the contact angles between the core and water are 69.8 °, 94.8 °, 110.4 °, 116.1 ° and 125.1 °, respectively. The surface free energy of the core can be calculated to be 73.2mN/m, 52.8 mN/m, 18.3mN/m, 12.8 mN/m and 8.7mN/m respectively by combining the contact angle data. Contact angle test results show that the gas-wetting reversal agent prepared herein has good hydrophobicity. After a certain mass fraction of emulsion is added into a reservoir, the wettability of the core can be changed from hydrophile to hydrophobic, and the wettability reversal is realized.
(6) Gas drive discharge rate: the synthetic gas wetting reversal agent is respectively prepared into 0.5 percent, 1.0 percent, 1.5 percent and 2.0 percent wt percent, quartz sand with 40 to 70 meshes is used as propping agent, the propping agent is put into a medium-pressure chromatographic column, two ends of the propping agent are sealed by plugs, the balance is used for weighing the total mass of the medium-pressure chromatographic column, the propping agent and the combination of the plugs at the two ends, the assembled medium-pressure chromatographic column is fixed by a iron stand table to be vertically placed, and a filling layer is saturated by a drainage aid aqueous solution. After saturation for 10min, the medium pressure chromatographic column is taken down, redundant liquid on the surface of the medium pressure chromatographic column is wiped off, the balance is used for weighing the total mass of the saturated medium pressure chromatographic column, the propping agent and plugs at two ends, the medium pressure chromatographic column filled with the saturated propping agent is continuously filled with nitrogen (10 kPa) for 5min, and the mass of the flowing FPA-3 emulsion is recorded to calculate the discharge rate. Each group was tested 3 times with clear water as a blank.
The formula for calculating the discharge rate is as follows:
wherein:
η R -drainage rate,%;
m 1 -mass of the pre-saturation composition, g;
m 2 -mass of the assembly after saturation, g;
m 3 the mass of the gas-wetting reversal agent discharged after saturation, g.
As shown in FIG. 6, when the mass fraction of the gas-wetting reversal agent is 2.0wt%, the discharge rate of the quartz sand with 40-70 meshes is increased from 19.89% to 29.47%, and compared with clear water, the discharge rate is gradually increased along with the increase of the mass fraction of the gas-wetting reversal agent. The drainage rate is increased and the drainage amount is increased due to the hydrophobic property of the emulsion when the emulsion flows through the surface of the propping agent. When the mass fraction is 2.0wt%, the discharge rate of the opposite-support 40-70 mesh quartz sand propping agent reaches 29.47%, so that the retention of stratum and crack liquid is obviously reduced, and the aim of quick flowback prevention of water lock is fulfilled.
The present invention is not limited to the preferred embodiments, but can be modified in any way according to the technical principles of the present invention, and all such modifications, equivalent variations and modifications are included in the scope of the present invention.

Claims (9)

1. The preparation method of the gas wetting reversal agent suitable for the surface of the compact sandstone is characterized by comprising the following steps of:
(1) Weighing dispersant and water to prepare dispersant solution with concentration of 3-5%, taking 5-7 parts of the dispersant solution, sealing, placing the dispersant solution in a constant-temperature water bath at 60 ℃ and stirring the dispersant solution by a constant-speed stirrer at 500 r/min;
(2) Uniformly mixing 1.8-2.0 parts of methacrylate monomers, 0.1 part of silane coupling agent and 0.5-2.0 parts of fluorine-containing monomers to prepare a solution B;
(3) Weighing 0.02-0.04 part of initiator, and dissolving 20mL of water to obtain solution C;
(4) When the temperature of the water bath is raised to 80-90 ℃, 1/3 solution B is taken and stirred for 3-5min, 1/3 solution C is added to obtain solution D, the system is blue, stirring is continued for 10-15min, the rest 2/3 solution B and 2/3 solution C are slowly dripped into the solution D, the dripping is completed in 2-3 hours, the temperature is raised to 85-90 ℃, the heat preservation reaction is continued for 2-5h, the emulsion is cooled to room temperature, and the air wetting reversal agent is obtained after discharging.
2. The method for preparing the dense sandstone surface air wetting reversal agent according to claim 1, wherein the method comprises the following steps: the dispersing agent is one or a mixture of two or more of acrylonitrile modified starch, ethanol, glycerol and polyvinyl alcohol in any proportion.
3. The method for preparing the gas-wetting reversal agent suitable for the surface of compact sandstone according to claim 2, which is characterized in that: the methacrylate monomer is one or a mixture of two or more than two of hexyl methacrylate, n-octyl methacrylate, glycerol methacrylate, methyl methacrylate and butyl acrylate in any proportion.
4. A method for preparing a dense sandstone surface air wetting reversal agent according to claim 3, wherein: the fluorine-containing monomer is trifluoroethyl acrylate, hexafluorobutyl acrylate, dodecafluoroheptyl acrylate, perfluorooctyl ethyl acrylate, nonafluoro acrylate, perfluorooctyl sulfonamide, trifluoroethyl methacrylate, hexafluorobutyl methacrylate, dodecafluoroheptyl methacrylate, nonafluoro methacrylate, perfluorooctyl sulfonamide or perfluoroalkyl ethyl acrylate.
5. The method for preparing the dense sandstone surface air wetting reversal agent, which is disclosed in claim 4, is characterized in that: the silane coupling agent is one or two of gamma-aminopropyl triethoxysilane, gamma-glycidol ether oxypropyl trimethoxysilane, gamma- (methacryloyloxy) propyl trimethoxysilane, N- (beta-aminoethyl) -gamma-aminopropyl trimethyl (ethoxysilane and N-beta- (aminoethyl) -gamma-aminopropyl methyl dimethoxy silane in any proportion.
6. The method for preparing the dense sandstone surface air wetting reversal agent, which is disclosed in claim 5, is characterized in that: the initiator is one or a mixture of two of potassium persulfate, ammonium persulfate, azodiisobutyronitrile and azodiisobutyl prochloraz hydrochloride in any proportion.
7. A gas-wetting reversal agent suitable for dense sandstone surfaces, prepared according to the preparation method of claim 1.
8. The application of the dense sandstone surface gas wetting reversal agent for improving the yield of a dense sandstone gas well according to claim 1, wherein fracturing fluid or water is added into the dense sandstone surface gas wetting reversal agent to prepare a reversal agent solution with the mass concentration of 0.5% -2%, the reversal agent solution is pumped into a dense sandstone reservoir until the surface of the dense sandstone reservoir is fully soaked in the reversal agent solution, and the contact treatment temperature of the wetting reversal agent solution and the surface of the dense sandstone reservoir is 60-130 ℃, and the soaking time is 4-8 hours.
9. The use of a tight sandstone surface gas wetting reversal agent according to claim 8, for increasing the production of tight sandstone gas wells, wherein the fracturing fluid is one or more of a slickwater fracturing fluid, a guar gum fracturing fluid, and a foam fracturing fluid.
CN202311031208.5A 2023-08-16 2023-08-16 Air wetting reversal agent suitable for compact sandstone surface, and preparation method and application thereof Active CN117089011B (en)

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