CN113880984A - Drag reducer and preparation method thereof - Google Patents
Drag reducer and preparation method thereof Download PDFInfo
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Abstract
The invention discloses a drag reducer and a preparation method thereof. The drag reducer disclosed by the invention has a better drag reduction rate no matter in clear water or saline water, the drag reduction rate can reach more than 76% under the condition that the addition amount is 0.1%, and the drag reduction rate can still reach more than 74% even under the condition that the salt content is 5%, so that the drag reducer disclosed by the invention has better salt resistance; meanwhile, even under the condition of long-time shearing, the drag reduction rate can still reach more than 70 percent, which shows that the drag reducer has better shearing resistance.
Description
Technical Field
The invention relates to the technical field of fracturing fluid additives, in particular to a drag reducer and a preparation method thereof.
Background
With the increase of drilling force in China, most shallow oil reservoirs/gas reservoirs reach the late production stage and even are exploited completely, so that deep wells and ultra-deep wells are more and more, and in the fracturing process, because the friction resistance of the fracturing fluid is too high, the pressure loss is large, and particularly for the ultra-deep wells, the pressure of the ultra-deep wells exceeds the limit of the conventional ground fracturing equipment.
Therefore, drag reducers are usually added into fracturing fluids at home and abroad to reduce the friction resistance of the night fracturing fluids and reduce the pressure loss in the fracturing process. Drag reducers are generally classified into high molecular polymer drag reducers, surfactant drag reducers and nanoparticle drag reducers, wherein the high molecular polymer drag reducers are the most commonly used drag reducers for fracturing fluids at present due to their advantages of good effect, low price, small dosage and the like.
For example, chinese patent CN112410013A discloses a suspension liquid drag reducer, which comprises a water-soluble polymer, a surfactant, a thickener and an oil solvent, and the drag reducer has a good final drag reduction effect and is easy to use by compounding the water-soluble polymer and the surfactant.
Chinese patent CN106317317A discloses an acrylamide terpolymer and drag reducer for fracturing and their preparation methods, which uses acrylamide, quaternary ammonium salt of acrylamide, and monohydric alcohol of acrylamide as polymerization monomers to polymerize, and compounds the polymerization product with stabilizer, inorganic salt, and water to obtain the drag reducer with good drag reduction performance.
However, the drag reducer has poor shear resistance due to the characteristics of the high-molecular polymer drag reducer, has a high degradation rate in the formation, is difficult to achieve the desired drag reduction effect in the subsequent process, and has a single effect.
Disclosure of Invention
In view of this, the present invention aims to provide a method for preparing a drag reducer, which not only has a better drag reduction ratio, but also has better shear resistance, and also has a certain shale inhibition effect.
The technical scheme provided by the invention is that the preparation method of the drag reducer comprises the following steps:
dissolving 1 mol part of polyethylene polyamine in a first solvent, dissolving 1 mol part of unsaturated quaternary ammonium salt in a second solvent, dropwise adding the unsaturated quaternary ammonium salt solution into the polyethylene polyamine solution at the temperature of 50-80 ℃ under the condition of nitrogen atmosphere and continuous stirring, maintaining the above conditions for continuous reaction for 2-4 h after dropwise adding is finished, and purifying after the reaction is finished to obtain G1;
dissolving 1 mol part of G1 in a first solvent, dissolving another 1 mol part of unsaturated quaternary ammonium salt in a second solvent, and repeating the steps for m-2 or m-1 times, wherein m is the number of hydrogen atoms on amino groups in polyethylene polyamine, thus obtaining branched quaternary ammonium salt G;
taking 1 mol part of branched quaternary ammonium salt G, and carrying out amidation reaction on the branched quaternary ammonium salt G and 1 mol part of unsaturated acyl chloride to prepare a branched quaternary ammonium salt monomer;
taking an acrylamide monomer, an acrylic acid monomer, an unsaturated polyoxyethylene ether monomer and a branched quaternary ammonium salt monomer in a weight ratio of 120-200: 50-110: 3-12: 2, sequentially adding the four monomers into water under the conditions of introducing nitrogen and continuously stirring to dissolve the four monomers and prepare an aqueous solution with the concentration of 20-30%, then adding an initiator, wherein the addition of the initiator is 0.3-0.5% of the total addition of the four monomers, and reacting for 6-10 hours to obtain the acrylic acid modified acrylic acid, wherein the reaction conditions are as follows: the temperature is 30-40 ℃, and the stirring speed is less than 100 r/min.
In one embodiment of the present invention, the polyethylene polyamine is one of diethylenetriamine, triethylenetetramine, tetraethylenepentamine, and pentaethylenehexamine.
In one embodiment of the present invention, the unsaturated quaternary ammonium salt is one of trimethylvinylammonium and triethylvinylammonium.
In one embodiment of the present invention, the first solvent is one of water, methanol, ethanol, acetone, toluene, and tetrahydrofuran, and the second solvent is one of water, methanol, ethanol, acetone, toluene, and tetrahydrofuran.
In one embodiment of the present invention, the unsaturated acid chloride is at least one of acryloyl chloride and methacryloyl chloride.
One embodiment of the present invention is that the unsaturated polyoxyethylene ether is allyl polyoxyethylene ether, wherein the polymerization degree of the oxyethylene is 5 to 15.
One embodiment of the invention is that the initiator consists of a water-soluble azo initiator and a persulfate in a mass ratio of 1:1, the water-soluble azo initiator is one of azobisisobutylamidine hydrochloride and azobisisobutylimidazoline hydrochloride, and the persulfate is one of potassium persulfate, ammonium persulfate and sodium persulfate.
One embodiment of the present invention is that the amidation reaction of the branched quaternary ammonium salt and the acid chloride comprises the following steps: respectively dissolving 1 mol part of the branched quaternary ammonium salt G and 1 mol part of unsaturated acyl chloride by using tetrahydrofuran, adding 1-1.2 mol parts of N, N-diisopropylethylamine at the temperature of-20-10 ℃ in a nitrogen atmosphere under the condition of continuously stirring, dropwise adding the unsaturated acyl chloride solution into the branched quaternary ammonium salt G solution, heating to 20-40 ℃, reacting for 30-100 min, and after the reaction is finished, recrystallizing by using trichloromethane to obtain the branched quaternary ammonium salt monomer.
It is another object of the present invention to provide a drag reducer prepared by any of the above-described methods.
The invention has the technical effects that: the drag reducer disclosed by the invention has a better drag reduction rate no matter in clear water or saline water, the drag reduction rate can reach more than 76% under the condition that the addition amount is 0.1%, and the drag reduction rate can still reach more than 74% even under the condition that the salt content is 5%, so that the drag reducer disclosed by the invention has better salt resistance; meanwhile, even under the condition of long-time shearing, the drag reduction rate can still reach more than 70 percent, which shows that the drag reducer has better shearing resistance.
The drag reducer of the invention contains the branched quaternary ammonium salt, so the drag reducer also has better shale inhibition performance, and the final shale inhibition effect is better than 2% of potassium chloride under the condition of 0.1% of addition amount.
Detailed Description
The present invention will be described in further detail with reference to examples.
In order to make the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the embodiments of the present invention will be described in detail and completely with reference to the accompanying drawings. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.
In the following examples, unless otherwise specified, all the substances are commercially available and can be purchased directly from the market.
A method of preparing a drag reducing agent comprising the steps of:
dissolving 1 mol part of polyethylene polyamine in a first solvent, dissolving 1 mol part of unsaturated quaternary ammonium salt in a second solvent, dropwise adding the unsaturated quaternary ammonium salt solution into the polyethylene polyamine solution at the temperature of 50-80 ℃ under the condition of nitrogen atmosphere and continuous stirring, maintaining the above conditions for continuous reaction for 2-4 h after dropwise adding is finished, and purifying after the reaction is finished to obtain G1;
dissolving 1 mol part of G1 in a first solvent, dissolving another 1 mol part of unsaturated quaternary ammonium salt in a second solvent, and repeating the steps for m-2 or m-1 times, wherein m is the number of hydrogen atoms on amino groups in polyethylene polyamine, thus obtaining branched quaternary ammonium salt G; in this step and the previous step, mainly unsaturated quaternary ammonium salts are reacted with polyethylenepolyamines by the Michael addition reaction, the polyethylenepolyamines generally having the following structural formula:
wherein n is an integer of 1 to 4.
Meanwhile, in the Michael addition reaction, the reactivity of secondary amine is greater than that of primary amine, so that the theoretical number of repeated reactions is m-1, leaving an amino group with active hydrogen (hydrogen on the amino group) to react with the subsequent unsaturated acid chloride, but the inventor finds in the actual practice that when the number of repeated reactions is adjusted to m-2, the properties of the final synthetic product are basically the same as those of m-1 repeated reactions.
Taking 1 mol part of branched quaternary ammonium salt G, and carrying out amidation reaction on the branched quaternary ammonium salt G and 1 mol part of unsaturated acyl chloride to prepare a branched quaternary ammonium salt monomer; the amidation of the acid chloride with a primary/secondary amine is a reaction which is conventional in the art, and therefore, the present invention is not limited to the reaction conditions as long as the amidation reaction can be caused to occur.
In some embodiments, the acid chloride and the branched quaternary ammonium salt G may be reacted in the following manner: respectively dissolving 1 mol part of the branched quaternary ammonium salt G and 1 mol part of unsaturated acyl chloride by using tetrahydrofuran, adding 1-1.2 mol parts of N, N-diisopropylethylamine at the temperature of-20-10 ℃ in a nitrogen atmosphere under the condition of continuously stirring, dropwise adding the unsaturated acyl chloride solution into the branched quaternary ammonium salt G solution, heating to 20-40 ℃, reacting for 30-100 min, and after the reaction is finished, recrystallizing by using trichloromethane to obtain the branched quaternary ammonium salt monomer.
In particular, the unsaturated acid chloride can be selected from commercially available unsaturated acid chlorides, but due to poor stability of the acid chloride, the unsaturated acid chloride can be prepared in a timely manner, for example, by using the corresponding carboxylic acid and a chlorinating agent.
Taking an acrylamide monomer, an acrylic acid monomer, an unsaturated polyoxyethylene ether monomer and a branched quaternary ammonium salt monomer in a weight ratio of 120-200: 50-110: 3-12: 2, sequentially adding the four monomers into water under the conditions of introducing nitrogen and continuously stirring to dissolve the four monomers and prepare an aqueous solution with the concentration of 20-30%, then adding an initiator, wherein the addition of the initiator is 0.3-0.5% of the total addition of the four monomers, and reacting for 6-10 hours to obtain the acrylic acid modified acrylic acid, wherein the reaction conditions are as follows: the temperature is 30-40 ℃, and the stirring speed is less than 100 r/min.
Generally speaking, for polymer drag reducers, linear polymers are suitable, so that a cross-linking agent is not suitable to be added, but a higher molecular weight is usually needed to achieve a better drag reduction effect, so that the final molecular weight is increased by adjusting the monomer concentration, adjusting the reaction time and reducing the addition of an initiator, and the final viscosity-average molecular weight can reach more than 1000 ten thousand through the reaction, so that the drag reduction effect is better.
The polyethylene polyamine is one of diethylenetriamine, triethylene tetramine, tetraethylene pentamine and pentaethylene hexamine.
The unsaturated quaternary ammonium salt is one of trimethyl vinyl ammonium and triethyl vinyl ammonium, and the unsaturated quaternary ammonium salt is a quaternary ammonium salt containing at least one double bond, but the space distance between the double bond and the quaternary ammonium ion is not suitable to be too long, and when the distance between the double bond and the quaternary ammonium ion is too long, the branching property of the finally synthesized branched quaternary ammonium monomer is weakened, so that the effect is relatively poor.
The first solvent is one of water, methanol, ethanol, acetone, toluene and tetrahydrofuran, and the second solvent is one of water, methanol, ethanol, acetone, toluene and tetrahydrofuran. The first solvent and the second solvent may be the same or different.
The unsaturated acyl chloride is at least one of acryloyl chloride and methacryloyl chloride. The unsaturated acid chloride may be used in various forms, such as long-chain unsaturated acid chloride, but the long-chain unsaturated acid chloride, such as undecylenic acid chloride, has a longer chain length and is less effective than the short-chain acryloyl chloride.
The unsaturated polyoxyethylene ether is allyl polyoxyethylene ether, and the structural formula is
Wherein n is an integer of 5-15.
The initiator consists of a water-soluble azo initiator and a persulfate in a mass ratio of 1:1, the water-soluble azo initiator is one of azodiisobutyl amidine hydrochloride and azodiisobutyl imidazoline hydrochloride, and the persulfate is one of potassium persulfate, ammonium persulfate and sodium persulfate. Due to the difference of the half-life periods of the two initiators, the molecular weight of the finally synthesized polymer can be increased, so that the effect of synthesizing the polymer is better.
The inventor finds that when the weight ratio of the acrylamide monomer, the acrylic acid monomer, the unsaturated polyoxyethylene ether monomer and the branched quaternary ammonium salt monomer is 140-160: 60-90: 7-11: and 2, the final product has better effect.
Another object of the present invention is to provide a drag reducer prepared by any of the above methods, which has a high drag reduction ratio and at the same time has the effects of killing bacteria and stabilizing the well wall.
Example 1
Preparing a branched quaternary ammonium salt monomer: respectively dissolving equal molar parts of triethylene tetramine and trimethyl vinyl ammonium bromide in acetone, dropwise adding the trimethyl vinyl ammonium bromide solution into the triethylene tetramine solution at 70 ℃ in a nitrogen atmosphere under the condition of continuous stirring, maintaining the above conditions for continuous reaction for 3 hours after dropwise adding is finished, and after the reaction is finished, carrying out reduced pressure distillation, washing with diethyl ether for multiple times, filtering and drying to obtain S1-G1;
taking equimolar amounts of S1-G1 and trimethyl vinyl ammonium bromide, repeating the steps for 5 times to finally prepare a branched quaternary ammonium salt S1-G; in this embodiment, the phrase "repeating the above steps 5 times in total" means that the phrase includes the initial step and the subsequent repeated step, 5 times in total.
Respectively dissolving equal molar parts of S1-G and acryloyl chloride in tetrahydrofuran, introducing nitrogen and continuously stirring under an ice bath condition, adding N, N-diisopropylethylamine into the S1-G solution, wherein the molar ratio of the N, N-diisopropylethylamine to the S1-G is 1.2:1, then dropwise adding the acryloyl chloride solution into the S1-G solution, slowly heating to 30 ℃ after dropwise adding, reacting for 50min, and after the reaction is finished, recrystallizing by using trichloromethane to obtain the branched quaternary ammonium salt monomer S1.
Preparing a drag reducer: 150g of acrylamide is dissolved in 800ml of water, and under the condition of continuously introducing nitrogen and continuously stirring (the stirring speed is 80r/min), 70g of acrylic acid, 10g of allyl polyoxyethylene ether (the polymerization degree of ethylene oxide is 8) and 2g of branched quaternary ammonium salt monomer S1 are sequentially added, wherein the next monomer can be added only after the former monomer is completely dissolved. And after complete dissolution, heating to 35 ℃, adding 0.9g of initiator to continuously react for 8 hours, wherein the initiator consists of azodiisobutyl amidine hydrochloride and potassium persulfate in a mass ratio of 1:1, and after the reaction is finished, distilling under reduced pressure, drying and crushing to obtain the azodiisobutyl amidine hydrochloride.
Example 2
Preparing a branched quaternary ammonium salt monomer: respectively dissolving equal molar parts of diethylenetriamine and trimethyl vinyl ammonium bromide in acetone, dropwise adding the trimethyl vinyl ammonium bromide solution into the diethylenetriamine solution at the temperature of 70 ℃ under the condition of nitrogen atmosphere and continuous stirring, maintaining the above conditions for continuous reaction for 3 hours after the dropwise addition is finished, and after the reaction is finished, carrying out reduced pressure distillation, washing with diethyl ether for many times, filtering and drying to obtain S2-G1;
taking equimolar amounts of S2-G1 and trimethyl vinyl ammonium bromide, repeating the steps for 4 times to finally prepare a branched quaternary ammonium salt S2-G; in this embodiment, the phrase "repeating the above steps 4 times in total" means that the phrase includes an initial step and a subsequent repeated step, 4 times in total.
Respectively dissolving equal molar parts of S2-G and acryloyl chloride in tetrahydrofuran, introducing nitrogen and continuously stirring under an ice bath condition, adding N, N-diisopropylethylamine into the S2-G solution, wherein the molar ratio of the N, N-diisopropylethylamine to the S2-G is 1.2:1, then dropwise adding the acryloyl chloride solution into the S2-G solution, slowly heating to 30 ℃ after dropwise adding, reacting for 50min, and after the reaction is finished, recrystallizing by using trichloromethane to obtain the branched quaternary ammonium salt monomer S2.
Preparing a drag reducer: 150g of acrylamide is dissolved in 800ml of water, and under the condition of continuously introducing nitrogen and continuously stirring (the stirring speed is 80r/min), 70g of acrylic acid, 10g of allyl polyoxyethylene ether (the polymerization degree of ethylene oxide is 8) and 2g of branched quaternary ammonium salt monomer S2 are sequentially added, wherein the next monomer can be added only after the former monomer is completely dissolved. And after complete dissolution, heating to 35 ℃, adding 0.9g of initiator to continuously react for 8 hours, wherein the initiator consists of azodiisobutyl amidine hydrochloride and potassium persulfate in a mass ratio of 1:1, and after the reaction is finished, distilling under reduced pressure, drying and crushing to obtain the azodiisobutyl amidine hydrochloride.
Example 3
Preparing a branched quaternary ammonium salt monomer: respectively dissolving equal molar parts of triethylene tetramine and trimethyl vinyl ammonium bromide in acetone, dropwise adding the trimethyl vinyl ammonium bromide solution into the triethylene tetramine solution at 70 ℃ in a nitrogen atmosphere under the condition of continuous stirring, maintaining the above conditions for continuous reaction for 3 hours after dropwise adding is finished, and after the reaction is finished, carrying out reduced pressure distillation, washing with diethyl ether for multiple times, filtering and drying to obtain S3-G1;
taking equimolar amounts of S3-G1 and trimethyl vinyl ammonium bromide, repeating the steps for 4 times to finally prepare a branched quaternary ammonium salt S3-G; in this embodiment, the phrase "repeating the above steps 4 times in total" means that the phrase includes an initial step and a subsequent repeated step, 4 times in total.
Respectively dissolving equal molar parts of S3-G and acryloyl chloride in tetrahydrofuran, introducing nitrogen and continuously stirring under an ice bath condition, adding N, N-diisopropylethylamine into the S3-G solution, wherein the molar ratio of the N, N-diisopropylethylamine to the S3-G is 1.2:1, then dropwise adding the acryloyl chloride solution into the S3-G solution, slowly heating to 30 ℃ after dropwise adding, reacting for 50min, and after the reaction is finished, recrystallizing by using trichloromethane to obtain the branched quaternary ammonium salt monomer S3.
Preparing a drag reducer: 150g of acrylamide is dissolved in 800ml of water, and under the condition of continuously introducing nitrogen and continuously stirring (the stirring speed is 80r/min), 70g of acrylic acid, 10g of allyl polyoxyethylene ether (the polymerization degree of ethylene oxide is 8) and 2g of branched quaternary ammonium salt monomer S3 are sequentially added, wherein the next monomer can be added only after the former monomer is completely dissolved. And after complete dissolution, heating to 35 ℃, adding 0.9g of initiator to continuously react for 8 hours, wherein the initiator consists of azodiisobutyl amidine hydrochloride and potassium persulfate in a mass ratio of 1:1, and after the reaction is finished, distilling under reduced pressure, drying and crushing to obtain the azodiisobutyl amidine hydrochloride.
Example 4
Preparing a branched quaternary ammonium salt monomer: respectively dissolving equal molar parts of triethylene tetramine and trimethyl vinyl ammonium bromide in acetone, dropwise adding the trimethyl vinyl ammonium bromide solution into the triethylene tetramine solution at 70 ℃ in a nitrogen atmosphere under the condition of continuous stirring, maintaining the above conditions for continuous reaction for 3 hours after dropwise adding is finished, and after the reaction is finished, carrying out reduced pressure distillation, washing with diethyl ether for multiple times, filtering and drying to obtain S4-G1;
taking equimolar amounts of S4-G1 and trimethyl vinyl ammonium bromide, repeating the steps for 5 times to finally prepare a branched quaternary ammonium salt S4-G; in this embodiment, the phrase "repeating the above steps 5 times in total" means that the phrase includes the initial step and the subsequent repeated step, 5 times in total.
Respectively dissolving equal molar parts of S4-G and 5-hexenoyl chloride in tetrahydrofuran, introducing nitrogen and continuously stirring under an ice bath condition, adding N, N-diisopropylethylamine into the S4-G solution, wherein the molar ratio of the N, N-diisopropylethylamine to the S4-G is 1.2:1, then dropwise adding the 5-hexenoyl chloride solution into the S4-G solution, slowly heating to 30 ℃ after dropwise adding is finished, reacting for 50min, and after the reaction is finished, recrystallizing by using trichloromethane to obtain the branched quaternary ammonium salt monomer S4.
Preparing a drag reducer: 150g of acrylamide is dissolved in 800ml of water, and under the condition of continuously introducing nitrogen and continuously stirring (the stirring speed is 80r/min), 70g of acrylic acid, 10g of allyl polyoxyethylene ether (the polymerization degree of ethylene oxide is 8) and 2g of branched quaternary ammonium salt monomer S4 are sequentially added, wherein the next monomer can be added only after the former monomer is completely dissolved. And after complete dissolution, heating to 35 ℃, adding 0.9g of initiator to continuously react for 8 hours, wherein the initiator consists of azodiisobutyl amidine hydrochloride and potassium persulfate in a mass ratio of 1:1, and after the reaction is finished, distilling under reduced pressure, drying and crushing to obtain the azodiisobutyl amidine hydrochloride.
Example 5
Preparing a branched quaternary ammonium salt monomer: respectively dissolving equal molar parts of triethylene tetramine and trimethyl vinyl ammonium bromide in acetone, dropwise adding the trimethyl vinyl ammonium bromide solution into the triethylene tetramine solution at 70 ℃ in a nitrogen atmosphere under the condition of continuous stirring, maintaining the above conditions for continuous reaction for 3 hours after dropwise adding is finished, and after the reaction is finished, carrying out reduced pressure distillation, washing with diethyl ether for multiple times, filtering and drying to obtain S5-G1;
taking equimolar amounts of S5-G1 and trimethyl vinyl ammonium bromide, repeating the steps for 5 times to finally prepare a branched quaternary ammonium salt S5-G; in this embodiment, the phrase "repeating the above steps 5 times in total" means that the phrase includes the initial step and the subsequent repeated step, 5 times in total.
Respectively dissolving equal molar parts of S5-G and acryloyl chloride in tetrahydrofuran, introducing nitrogen and continuously stirring under an ice bath condition, adding N, N-diisopropylethylamine into the S5-G solution, wherein the molar ratio of the N, N-diisopropylethylamine to the S5-G is 1.2:1, then dropwise adding the acryloyl chloride solution into the S5-G solution, slowly heating to 30 ℃ after dropwise adding, reacting for 50min, and after the reaction is finished, recrystallizing by using trichloromethane to obtain the branched quaternary ammonium salt monomer S5.
Preparing a drag reducer: 120g of acrylamide is dissolved in 800ml of water, and 100g of acrylic acid, 5g of allyl polyoxyethylene ether (the polymerization degree of ethylene oxide is 8) and 2g of branched quaternary ammonium salt monomer S5 are sequentially added under the condition of continuously introducing nitrogen and continuously stirring (the stirring speed is 80r/min), wherein the next monomer can be added only after the former monomer is completely dissolved. And after complete dissolution, heating to 35 ℃, adding 0.9g of initiator to continuously react for 8 hours, wherein the initiator consists of azodiisobutyl amidine hydrochloride and potassium persulfate in a mass ratio of 1:1, and after the reaction is finished, distilling under reduced pressure, drying and crushing to obtain the azodiisobutyl amidine hydrochloride.
Comparative example 1
Preparing a branched quaternary ammonium salt monomer: respectively dissolving equal molar parts of triethylene tetramine and trimethyl vinyl ammonium bromide in acetone, dropwise adding the trimethyl vinyl ammonium bromide solution into the triethylene tetramine solution at 70 ℃ in a nitrogen atmosphere under the condition of continuous stirring, maintaining the above conditions for continuous reaction for 3 hours after dropwise adding is finished, and after the reaction is finished, carrying out reduced pressure distillation, washing with diethyl ether for multiple times, filtering and drying to obtain D1-G1;
taking equimolar amounts of D1-G1 and trimethyl vinyl ammonium bromide, repeating the steps for 3 times to finally prepare a branched quaternary ammonium salt D1-G; in this embodiment, the phrase "repeating the above steps 3 times in total" means that the phrase includes the initial step and the subsequent repeated step, 3 times in total.
Respectively dissolving equal molar parts of D1-G and acryloyl chloride in tetrahydrofuran, introducing nitrogen and continuously stirring under an ice bath condition, adding N, N-diisopropylethylamine into a D1-G solution, wherein the molar ratio of the N, N-diisopropylethylamine to the D1-G is 1.2:1, then dropwise adding the acryloyl chloride solution into the D1-G solution, slowly heating to 30 ℃ after dropwise adding, reacting for 50min, and after the reaction is finished, recrystallizing by using trichloromethane to obtain the branched quaternary ammonium salt monomer D1.
Preparing a drag reducer: 150g of acrylamide is dissolved in 800ml of water, and under the condition of continuously introducing nitrogen and continuously stirring (the stirring speed is 80r/min), 70g of acrylic acid, 10g of allyl polyoxyethylene ether (the polymerization degree of ethylene oxide is 8) and 2g of branched quaternary ammonium salt monomer D1 are sequentially added, wherein the next monomer can be added only after the former monomer is completely dissolved. And after complete dissolution, heating to 35 ℃, adding 0.9g of initiator to continuously react for 8 hours, wherein the initiator consists of azodiisobutyl amidine hydrochloride and potassium persulfate in a mass ratio of 1:1, and after the reaction is finished, distilling under reduced pressure, drying and crushing to obtain the azodiisobutyl amidine hydrochloride.
Comparative example 2
Preparing a branched quaternary ammonium salt monomer: respectively dissolving equal molar parts of triethylene tetramine and trimethyl vinyl ammonium bromide in acetone, dropwise adding the trimethyl vinyl ammonium bromide solution into the triethylene tetramine solution at 70 ℃ in a nitrogen atmosphere under the condition of continuous stirring, maintaining the above conditions for continuous reaction for 3 hours after dropwise adding is finished, and after the reaction is finished, carrying out reduced pressure distillation, washing with diethyl ether for multiple times, filtering and drying to obtain D2-G1;
taking equimolar amounts of D2-G1 and trimethyl vinyl ammonium bromide, and repeating the steps for 5 times to finally prepare a branched quaternary ammonium salt D2-G; in this embodiment, the phrase "repeating the above steps 5 times in total" means that the phrase includes the initial step and the subsequent repeated step, 5 times in total.
Respectively dissolving equal molar parts of D2-G and acryloyl chloride in tetrahydrofuran, introducing nitrogen and continuously stirring under an ice bath condition, adding N, N-diisopropylethylamine into a D2-G solution, wherein the molar ratio of the N, N-diisopropylethylamine to the D2-G is 1.2:1, then dropwise adding the acryloyl chloride solution into the D2-G solution, slowly heating to 30 ℃ after dropwise adding, reacting for 50min, and after the reaction is finished, recrystallizing by using trichloromethane to obtain the branched quaternary ammonium salt monomer D2.
Preparing a drag reducer: 150g of acrylamide is dissolved in 800ml of water, and under the condition of continuously introducing nitrogen and continuously stirring (the stirring speed is 80r/min), 70g of acrylic acid, 10g of allyl polyoxyethylene ether (the polymerization degree of ethylene oxide is 8) and 2g of branched quaternary ammonium salt monomer D2 are sequentially added, wherein the next monomer can be added only after the former monomer is completely dissolved. And after complete dissolution, heating to 35 ℃, adding 0.9g of potassium persulfate, continuously reacting for 8 hours, and after the reaction is finished, distilling under reduced pressure, drying and crushing to obtain the potassium persulfate.
Comparative example 3
Preparing a branched quaternary ammonium salt monomer: respectively dissolving equal molar parts of triethylene tetramine and trimethyl vinyl ammonium bromide in acetone, dropwise adding the trimethyl vinyl ammonium bromide solution into the triethylene tetramine solution at 70 ℃ in a nitrogen atmosphere under the condition of continuous stirring, maintaining the above conditions for continuous reaction for 3 hours after dropwise adding is finished, and after the reaction is finished, carrying out reduced pressure distillation, washing with diethyl ether for multiple times, filtering and drying to obtain D3-G1;
taking equimolar amounts of D3-G1 and trimethyl vinyl ammonium bromide, and repeating the steps for 5 times to finally prepare a branched quaternary ammonium salt D3-G; in this embodiment, the phrase "repeating the above steps 5 times in total" means that the phrase includes the initial step and the subsequent repeated step, 5 times in total.
Respectively dissolving equal molar parts of D3-G and acryloyl chloride in tetrahydrofuran, introducing nitrogen and continuously stirring under an ice bath condition, adding N, N-diisopropylethylamine into a D3-G solution, wherein the molar ratio of the N, N-diisopropylethylamine to the D3-G is 1.2:1, then dropwise adding the acryloyl chloride solution into the D3-G solution, slowly heating to 30 ℃ after dropwise adding, reacting for 50min, and after the reaction is finished, recrystallizing by using trichloromethane to obtain the branched quaternary ammonium salt monomer D3.
Preparing a drag reducer: 150g of acrylamide is dissolved in 800ml of water, and under the condition of continuously introducing nitrogen and continuously stirring (the stirring speed is 200r/min), 70g of acrylic acid, 10g of allyl polyoxyethylene ether (the polymerization degree of ethylene oxide is 8) and 2g of branched quaternary ammonium salt monomer D3 are sequentially added, wherein the next monomer can be added only after the former monomer is completely dissolved. And after complete dissolution, heating to 35 ℃, adding 0.9g of initiator to continuously react for 8 hours, wherein the initiator consists of azodiisobutyl amidine hydrochloride and potassium persulfate in a mass ratio of 1:1, and after the reaction is finished, distilling under reduced pressure, drying and crushing to obtain the azodiisobutyl amidine hydrochloride.
Comparative example 4
Preparing a branched quaternary ammonium salt monomer: respectively dissolving 1 mol part of triethylene tetramine and 5 mol parts of trimethyl vinyl ammonium bromide in acetone, dropwise adding the trimethyl vinyl ammonium bromide solution into the triethylene tetramine solution at 70 ℃ in a nitrogen atmosphere under the condition of continuous stirring, maintaining the above conditions for continuous reaction for 3 hours after the dropwise addition is finished, and obtaining D14-G after the reaction is finished by reduced pressure distillation, ether washing for multiple times, filtering and drying;
respectively dissolving equal molar parts of D4-G and acryloyl chloride in tetrahydrofuran, introducing nitrogen and continuously stirring under an ice bath condition, adding N, N-diisopropylethylamine into a D4-G solution, wherein the molar ratio of the N, N-diisopropylethylamine to the D4-G is 1.2:1, then dropwise adding the acryloyl chloride solution into the D4-G solution, slowly heating to 30 ℃ after dropwise adding, reacting for 50min, and after the reaction is finished, recrystallizing by using trichloromethane to obtain the branched quaternary ammonium salt monomer D4.
Preparing a drag reducer: 150g of acrylamide is dissolved in 800ml of water, and under the condition of continuously introducing nitrogen and continuously stirring (the stirring speed is 80r/min), 70g of acrylic acid, 10g of allyl polyoxyethylene ether (the polymerization degree of ethylene oxide is 8) and 2g of branched quaternary ammonium salt monomer D4 are sequentially added, wherein the next monomer can be added only after the former monomer is completely dissolved. And after complete dissolution, heating to 35 ℃, adding 0.9g of initiator to continuously react for 8 hours, wherein the initiator consists of azodiisobutyl amidine hydrochloride and potassium persulfate in a mass ratio of 1:1, and after the reaction is finished, distilling under reduced pressure, drying and crushing to obtain the azodiisobutyl amidine hydrochloride.
To further illustrate the effectiveness of the drag reducing agents prepared in accordance with the present invention, they are tested below.
1. Drag reduction ratio
The apparatus used was: friction-reducing resistance tester, Nantong instrument, laboratory instruments, Inc.
The drag reducers prepared in examples 1 to 5 and comparative examples 1 to 3 were prepared as solutions of 0.1% by mass percentage using clear water and 5% aqueous sodium chloride solution as solvents at 25 ± 1 ℃, and drag reduction rate tests were performed after circulating in an experimental line for various times, and the flow rate of the liquid phase during circulation was 6 m/s. The test results are shown in tables 1 and 2.
TABLE 1 drag reduction ratio of drag reducer in clear water
TABLE 25 drag reduction ratio of drag reducer in aqueous sodium chloride solution
As can be seen from the data in tables 1 and 2: the drag reducer prepared by the invention has good drag reduction effect, and the highest drag reduction rate can reach more than 76% under the condition that the addition amount is 0.1%; referring to the test results of the drag reducers in examples 1 and 4, it is shown that short chain unsaturated acid chlorides have a better effect; referring to the test results of example 1 and example 5, it is demonstrated that the drag reducer prepared from the components has a good drag reduction effect only under a good proportioning condition; referring to the test results of the drag reducer in example 1 and comparative example 1, it is illustrated that when the total number of repetitions is less than m-2, the drag reducer obtained is less effective; referring to the test results for drag reducers in example 1 and comparative example 2, it is shown that the impact of the initiator on the final results is large; referring to the test results for the drag reducer in example 1 and comparative example 3, it is illustrated that in the case of too fast a stirring speed, it has an adverse effect on the synthesis of the drag reducer; referring to the results of the drag reducer tests in example 1 and comparative example 4, it is illustrated that the synthesis of the branched quaternary ammonium salt monomer has a dramatic effect on the drag reducing properties of the drag reducer.
Meanwhile, as seen from the comparison between tables 1 and 2, the drag reducer prepared by the invention has better salt resistance.
2. Shale inhibition
The drag reducer is generally used for a fracturing fluid of a shale formation, the fracturing fluid contacts with the shale formation during the fracturing process, hydration expansion of shale is avoided during the fracturing process, a 0.1% aqueous solution is prepared from the drag reducers in examples 1 to 5 and comparative examples 1 to 4, a shale rolling recovery rate test is performed at 180 ℃ by adopting a SYT6335-1997 method, and in order to illustrate the effect of each drag reducer in examples 1 to 5, potassium chloride with the weight percentage of 2% is used as a comparison, and the test results are shown in Table 3.
Table 3 shale inhibition test
| Sample (I) | The recovery rate is high |
| Clean water | 14.6 |
| 2% Potassium chloride | 56.8 |
| Example 1 | 69.5 |
| Example 2 | 68.7 |
| Example 3 | 67.3 |
| Example 4 | 65.6 |
| Example 5 | 62.7 |
| Comparative example 1 | 56.1 |
| Comparative example 2 | 67.3 |
| Comparative example 3 | 65.5 |
| Comparative example 4 | 42.7 |
As can be seen from table 3, the drag reducer of the present invention still has a better shale inhibition performance at an addition of 0.1% relative to 2% of potassium chloride.
The above description is only a preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the embodiments of the present invention are included in the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.
Claims (10)
1. A method of producing a drag reducing agent, comprising the steps of:
dissolving 1 mol part of polyethylene polyamine in a first solvent, dissolving 1 mol part of unsaturated quaternary ammonium salt in a second solvent, dropwise adding the unsaturated quaternary ammonium salt solution into the polyethylene polyamine solution at the temperature of 50-80 ℃ under the condition of nitrogen atmosphere and continuous stirring, maintaining the above conditions for continuous reaction for 2-4 h after dropwise adding is finished, and purifying after the reaction is finished to obtain G1;
dissolving 1 mol part of G1 in a first solvent, dissolving another 1 mol part of unsaturated quaternary ammonium salt in a second solvent, and repeating the steps for m-2 or m-1 times to obtain a branched quaternary ammonium salt G, wherein m is the number of hydrogen atoms on amino groups in the polyethylene polyamine;
taking 1 mol part of branched quaternary ammonium salt G, and carrying out amidation reaction on the branched quaternary ammonium salt G and 1 mol part of unsaturated acyl chloride to prepare a branched quaternary ammonium salt monomer;
taking an acrylamide monomer, an acrylic acid monomer, an unsaturated polyoxyethylene ether monomer and a branched quaternary ammonium salt monomer in a weight ratio of 120-200: 50-110: 3-12: 2, sequentially adding the four monomers into water under the conditions of introducing nitrogen and continuously stirring to dissolve the four monomers and prepare an aqueous solution with the concentration of 20-30%, then adding an initiator, wherein the addition of the initiator is 0.3-0.5% of the total addition of the four monomers, and reacting for 6-10 hours to obtain the acrylic acid modified acrylic acid, wherein the reaction conditions are as follows: the temperature is 30-40 ℃, the stirring speed is less than 100r/min, and the initiator comprises a water-soluble azo initiator and persulfate in a weight ratio of 1: 1.
2. The method of producing a drag reducer according to claim 1, wherein the polyethylene polyamine is one of diethylenetriamine, triethylenetetramine, tetraethylenepentamine, and pentaethylenehexamine.
3. The drag reducer production method according to claim 1, wherein the unsaturated quaternary ammonium salt is one of trimethyl vinyl ammonium bromide and triethyl vinyl ammonium bromide.
4. The method of producing a drag reducer according to claim 1, wherein the first solvent is one of water, methanol, ethanol, acetone, toluene, and tetrahydrofuran, and the second solvent is one of water, methanol, ethanol, acetone, toluene, and tetrahydrofuran.
5. The method of producing a drag reducer according to claim 1, wherein said unsaturated acid chloride is at least one of acryloyl chloride and methacryloyl chloride.
6. The method of producing a drag reducer according to claim 1, wherein the water-soluble azo initiator is one of azobisisobutylamidine hydrochloride and azobisisobutylimidazoline hydrochloride, and the persulfate is one of potassium persulfate, ammonium persulfate, and sodium persulfate.
7. The method for producing a drag reducer according to claim 1, wherein the unsaturated polyoxyethylene ether is allyl polyoxyethylene ether, and the degree of polymerization of the oxyethylene is 5 to 15.
8. The method of producing a drag reducer according to claim 1, wherein said amidation of said branched quaternary ammonium salt with said acid chloride comprises the steps of: respectively dissolving 1 mol part of the branched quaternary ammonium salt G and 1 mol part of unsaturated acyl chloride by using tetrahydrofuran, adding 1-1.2 mol parts of N, N-diisopropylethylamine at the temperature of-20-10 ℃ in a nitrogen atmosphere under the condition of continuously stirring, dropwise adding the unsaturated acyl chloride solution into the branched quaternary ammonium salt G solution, heating to 20-40 ℃, reacting for 30-100 min, and after the reaction is finished, recrystallizing by using trichloromethane to obtain the branched quaternary ammonium salt monomer.
9. The preparation method of the drag reducer according to claim 1, wherein the weight ratio of the acrylamide monomer, the acrylic acid monomer, the unsaturated polyoxyethylene ether monomer and the branched quaternary ammonium salt monomer is 140-160: 60-90: 7-11: 2.
10. a drag reducing agent prepared by the process of any one of claims 1-9.
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