Salt-sensitive viscoelastic gel profile control agent and preparation method thereof

Abstract

The application relates to the technical field of oil extraction, and discloses a salt-sensitive viscoelastic gel profile control agent and a preparation method thereof. The profile control agent is prepared by mixing a viscoelastic amphoteric polymer as a base material and phenolic resin and a regulator as auxiliary materials. The amphoteric crosslinking agent containing sulfonic acid anions and quaternary ammonium cations is prepared, participates in the crosslinking polymerization of polyacrylamide, and the viscoelastic amphoteric polymer is prepared. First, the crosslinking polymerization can make the polyacrylamide molecular chain have a crosslinking structure and gel characteristics, realizes high viscoelasticity of the profile control agent, and plays a good profile control role. Secondly, the existence of the sulfonic acid anions can effectively reduce the oil-water interfacial tension, can improve the salt sensitivity of the profile control agent, and can enhance the salt resistance of the profile control agent. The quaternary ammonium cations carry positive charges, the amide groups on the polyacrylamide molecular chain can form hydrogen bonds with particles, and the two can synergize to form a "multi-point adsorption-bridge" structure, so that the plugging efficiency is remarkably improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the oil field production technology field, and particularly relates to a salt-sensitive viscoelastic gel profile control agent and a preparation method thereof. BACKGROUND

[0002] With the global oilfield development into the middle and later period, high water cut, and the heterogeneity aggravation become a common problem. At present, more than 80% of the water drive oilfield water cut is generally high, and the main oil reservoir temperature is concentrated in 40-80 DEG C, and the salinity is generally higher than 30000mg / L. Under this condition, the traditional profile control technology faces great problems. The conventional polyacrylamide gel is difficult to form effective plugging due to the difference in the migration speed of the crosslinking agent and the polymer caused by the difference in the molecular weight. Moreover, the acrylamide monomer is easy to hydrolyze at high temperature, and when the salinity exceeds a certain value, the viscosity retention rate of the polyacrylamide solution will decrease seriously.

[0003] At present, phenolic resin and the like can be used as a crosslinking agent to be mixed with polyacrylamide to form a three-dimensional network structure, so as to improve the comprehensive performance of the polyacrylamide gel profile control agent. However, the actual application of this technology has defects, and cannot solve the problem of the large decrease in the viscosity retention rate caused by high salinity. Based on this, the present application prepares a polyacrylamide gel profile control agent with special functional groups through special molecular structure design, so as to solve the problems existing in the prior art. SUMMARY

[0004] (I) Technical problems solved

[0005] In view of the deficiencies of the prior art, the present application provides a salt-sensitive viscoelastic gel profile control agent and a preparation method thereof.

[0006] (II) Technical scheme

[0007] A salt-sensitive viscoelastic gel profile control agent comprises the following raw materials measured by weight fraction:

[0008] 30-45 parts of a viscoelastic amphoteric polymer, 10-15 parts of a phenolic resin, and 0.2-0.6 parts of a regulator;

[0009] The preparation method of the viscoelastic amphoteric polymer comprises the following steps:

[0010] Step one, acrylamide and itaconic acid are added to deionized water, and after being uniformly mixed by mechanical stirring, an initiator is continuously added, and after the addition is completed, the temperature is increased to 70-80 DEG C, and the polymerization is continuously maintained for 1-3h to form a prepolymer;

[0011] Step two, reduce the temperature to 40-50℃, then add the amphoteric crosslinking agent to the prepolymer, after adding, mechanically stir evenly, then adjust the temperature to 80-85℃, continue to incubate polymerization for 6-9h, stop heating, cool down and discharge, then the viscoelastic amphoteric polymer is prepared.

[0012] As a further scheme of the present application, the regulator is at least one of ammonia, oxalic acid, and sodium hydroxide.

[0013] As a further scheme of the present application, in step one, the mass ratio of acrylamide, itaconic acid, deionized water, initiator, and amphoteric crosslinking agent is 20-30:2-4:60-80:0.1-0.3:1-2.

[0014] As a further scheme of the present application, in step one, the initiator is a mixture of potassium persulfate and sodium sulfite, and the mass ratio is 2-3:1.

[0015] As a further scheme of the present application, in step two, the preparation method of the amphoteric crosslinking agent comprises the following steps:

[0016] Step S1, add 3-chloro-2-hydroxypropane sulfonic acid to acetone, protect with nitrogen, start stirring, after forming a uniform reaction solution, place in an ice bath environment, then add a functionalizing agent and a catalyst to the reaction solution, after adding, remove the ice bath, stir at a temperature of 30-35℃ for 3-6h, evaporate the solvent, collect the product, and prepare the crosslinking agent intermediate;

[0017] Step S2, add N-dodecyl-N,N-bis(2-hydroxyethyl) benzyl ammonium chloride and toluene to the reaction kettle filled with nitrogen, after adding, stir and mix uniformly, then add an aqueous alkaline hydroxide solution dropwise to the reaction kettle, stir at a temperature of 50-60℃ for 1-2h, then add the crosslinking agent intermediate to the reaction kettle, after adding, warm up to 80-90℃, stir for 6-8h, then evaporate the solvent, cool down and discharge, and the amphoteric crosslinking agent is prepared.

[0018] As a further scheme of the present application, in step S1, the functionalizing agent is acryloyl chloride or methacryloyl chloride.

[0019] As a further scheme of the present application, in step S1, the catalyst is pyridine or triethylamine.

[0020] As a further scheme of the present application, in step S2, the molar ratio of N-dodecyl-N,N-bis(2-hydroxyethyl) benzyl ammonium chloride to the crosslinking agent intermediate is 1:2.

[0021] As a further scheme of the present application, in step S2, the aqueous alkali hydroxide solution is an aqueous sodium hydroxide solution or an aqueous potassium hydroxide solution with a mass fraction of 10-20%.

[0022] In the above technical scheme, first, the functionalization reagent is used to modify the 3-chloro-2-hydroxypropane sulfonic acid, and the sulfonic acid derivative containing unsaturated alkyl functional groups is prepared by using the principle that the acyl chloride substituent in the structure can react with the hydroxyl substituent; then, under the catalysis of the alkali hydroxide, the halogen substituent in the structure can be substituted with the active hydroxyl substituent in the structure of N-dodecyl-N,N-bis(2-hydroxyethyl) benzyl ammonium chloride, so that the polymerization monomer containing sulfonic acid anion and quaternary ammonium cation is prepared, and by controlling the molar ratio of the reactants, the polymerization monomer containing two equivalents of unsaturated alkyl functional groups can be prepared, and the amphoteric crosslinking agent is prepared.

[0023] A preparation method of a salt-sensitive viscoelastic gel profile control agent, comprising the following steps:

[0024] Firstly, the raw materials are weighed according to the weight fraction and prepared for use;

[0025] Secondly, the viscoelastic amphoteric polymer, phenolic resin and regulator are added into a mixer, the stirring speed is controlled to be 1000-2000 r / min, and mechanical stirring is carried out for 10-30 min.

[0026] (Three) beneficial technical effects

[0027] The amphoteric crosslinking agent containing sulfonic acid anion and quaternary ammonium cation in the structure is prepared, and participates in the crosslinking polymerization of polyacrylamide, so that the polyacrylamide molecular chain containing sulfonic acid anion and quaternary ammonium cation is prepared. On the one hand, the crosslinking polymerization can make the polyacrylamide molecular chain have a crosslinking structure and have a gel property, which is beneficial to realize the high viscoelasticity of the profile control agent, can be injected into a deep bottom layer, and can effectively plug the high permeation channels and cracks in the formation, thereby playing a good profile control effect. On the other hand, the presence of the sulfonic acid anion can not only improve the water solubility of the polyacrylamide and effectively reduce the oil-water interfacial tension, but also can improve the salt sensitivity of the profile control agent and enhance the salt resistance of the profile control agent. In addition, the quaternary ammonium cation carries a positive charge, can efficiently neutralize the negatively charged colloidal particles and suspended matters in the formation, destroy the stability of the colloidal particles, and promote the aggregation of the particles. This feature can effectively plug the high permeation channels, adjust the water injection profile, and the amide group (-CONH2) on the polyacrylamide molecular chain can form a hydrogen bond with the particles and an electrostatic adsorption with the quaternary ammonium cation, thereby forming a "multi-point adsorption-bridge" structure. The synergistic effect makes the floc more compact and the settling speed faster, and significantly improves the plugging efficiency. DETAILED DESCRIPTION

[0028] For the purpose of promoting the understanding of the present application, a more comprehensive description will be given below. The following presents the preferred embodiments of the present application. However, the present application can be realized in many different forms and should not be limited to the embodiments described herein. On the contrary, these embodiments are provided so that this disclosure will be thorough and complete, and fully convey the scope of the present application to those skilled in the art.

[0029] Preparation Example

[0030] Preparation of viscoelastic amphoteric polymer:

[0031] Step one, 12g of acrylamide and 1.5g of itaconic acid are added to 40mL of deionized water, mechanically stirred to mix evenly, then 0.1g of potassium persulfate and 0.05g of sodium sulfite are added, after adding, the temperature is raised to 75℃, and the polymerization is continued for 2h, forming a prepolymer;

[0032] Step two, the temperature is reduced to 45℃, then 0.8g of amphoteric crosslinking agent is added to the prepolymer, after adding, it is mechanically stirred to mix evenly, then the temperature is adjusted to 82℃, and the polymerization is continued for 8h, then the heating is stopped, and the temperature is lowered to discharge, thus the viscoelastic amphoteric polymer is prepared.

[0033] The preparation method of the amphoteric crosslinking agent includes the following steps:

[0034] Step S1, 0.3g of 3-chloro-2-hydroxypropane sulfonic acid is added to acetone, protected by nitrogen, and stirred, then placed in an ice bath environment, then 0.16g of acryloyl chloride and 0.01g of pyridine are added to the reaction solution, after adding, the ice bath is removed, and stirred at a temperature of 35℃ for 4h, then the solvent is evaporated to remove, and the product is collected, thus the crosslinking agent intermediate is prepared;

[0035] Step S2, 0.5g of N-dodecyl-N,N-bis(2-hydroxyethyl) benzyl ammonium chloride and toluene are added to a nitrogen-filled reaction kettle, after adding, stirred to mix evenly, then 10mL of 15% sodium hydroxide aqueous solution is added dropwise to the reaction kettle, stirred at a temperature of 55℃ for 2h, then 0.57g of the crosslinking agent intermediate is added to the reaction kettle, after adding, the temperature is raised to 85℃, and stirred for 8h, then the solvent is evaporated to remove, and the temperature is lowered to discharge, thus the amphoteric crosslinking agent is prepared.

[0036] A salt-sensitive viscoelastic gel profile control agent, comprising the following raw materials measured by weight fraction:

[0037] Viscoelastic amphoteric polymer 30 parts, phenolic resin 10 parts, regulator ammonia 0.2 parts;

[0038] The preparation method of the viscoelastic gel profile control agent includes the following steps:

[0039] First step, each raw material is weighed according to the weight fraction, standby;

[0040] Second step, the viscoelastic amphoteric polymer, phenolic resin and regulator are added into the mixer, the stirring speed is controlled at 1000r / min, and mechanical stirring is mixed for 30min.

[0041] The preparation method of the viscoelastic amphoteric polymer is shown in the preparation example, and the following are the same. Example two:

[0042] A salt-sensitive viscoelastic gel profile control agent, comprising the following raw materials measured by weight fraction:

[0043] Viscoelastic amphoteric polymer 35 parts, phenolic resin 12 parts, regulator oxalic acid 0.5 parts;

[0044] The preparation method of the viscoelastic gel profile control agent comprises the following steps:

[0045] First step, each raw material is weighed according to the weight fraction, standby;

[0046] Second step, the viscoelastic amphoteric polymer, phenolic resin and regulator are added into the mixer, the stirring speed is controlled at 1500r / min, and mechanical stirring is mixed for 20min.

[0047] A salt-sensitive viscoelastic gel profile control agent, comprising the following raw materials measured by weight fraction:

[0048] Viscoelastic amphoteric polymer 45 parts, phenolic resin 15 parts, regulator oxalic acid 0.6 parts;

[0049] The preparation method of the viscoelastic gel profile control agent comprises the following steps:

[0050] First step, each raw material is weighed according to the weight fraction, standby;

[0051] Second step, the viscoelastic amphoteric polymer, phenolic resin and regulator are added into the mixer, the stirring speed is controlled at 2000r / min, and mechanical stirring is mixed for 10min.

[0052] Comparative example 1

[0053] A salt-sensitive viscoelastic gel profile control agent, comprising the following raw materials measured by weight fraction:

[0054] Viscoelastic amphoteric polymer 35 parts, phenolic resin 12 parts, regulator oxalic acid 0.5 parts, water 15000 parts;

[0055] The preparation method of the viscoelastic gel profile control agent comprises the following steps:

[0056] First step, each raw material is weighed according to the weight fraction, standby;

[0057] Second step, the viscoelastic amphoteric polymer, phenolic resin and regulator are added into the mixer, the stirring speed is controlled at 1500r / min, and mechanical stirring is mixed for 20min.

[0058] The difference between the preparation method of the viscoelastic amphoteric polymer and the preparation example is that no amphoteric crosslinking agent is added, and the rest is the same.

[0059] Performance test

[0060] a, pour the profile control agent in the examples and comparative examples into the mold, stand for 4h, then use a rotary viscometer for viscosity test, select No. 2 rotor, and set the shear rate to 7.34s -1 .

[0061] b, control the mass fraction of the profile control agent to be 0.5%, add the profile control agent in the examples and comparative examples into the simulated brine with a salinity of 12400mg / L, Ca 2+ and Mg 2+ content of 200mg / L, stir and mix uniformly, stand for 4h, then perform viscosity test, calculate the viscosity retention rate, and perform interfacial tension test using an interfacial tension meter;

[0062] The test results are shown in the following table:

[0063] Table 1-Test results

[0064]

[0065] According to the test result analysis, the profile control agent prepared by adding the amphoteric crosslinking agent has obviously better viscoelasticity and salt resistance effect. After removing the amphoteric crosslinking agent, the polyacrylamide molecular chain prepared does not contain sulfonic acid anion and quaternary ammonium cation, and also cannot form a crosslinked structure, resulting in a significant decrease in the effect of the profile control agent.

[0066] In the description of the present specification, the description of the reference terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above terms is not necessarily for the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any appropriate manner in any one or more embodiments or examples. In addition, the skilled in the art can combine and combine the different embodiments or examples described in the present specification and the features of the different embodiments or examples without contradiction.

[0067] The above description is only the ideal embodiment of the present application. Based on the above description, the related person can make various changes and modifications without departing from the technical idea of the present application. The technical scope of the present application is not limited to the content of the specification, and must be determined by the scope of the claims.

Claims

1. A salt-sensitive viscoelastic gel modifier, characterized in that, Including the following raw materials measured in parts by weight: 30-45 parts viscoelastic amphoteric polymer, 10-15 parts phenolic resin, and 0.2-0.6 parts modifier; The regulator is at least one of ammonia, oxalic acid, and sodium hydroxide. The preparation method of the viscoelastic amphoteric polymer includes the following steps: Step 1: Add acrylamide and itaconic acid to deionized water, mix thoroughly by mechanical stirring, then add the initiator. After the initiator is added, raise the temperature to 70-80℃ and continue to polymerize at this temperature for 1-3 hours to form a prepolymer. Step 2: Lower the temperature to 40-50℃, then add the amphoteric crosslinking agent to the prepolymer. After the addition is complete, stir mechanically until uniform. Then adjust the temperature to 80-85℃ and continue to polymerize at this temperature for 6-9 hours. After that, stop heating, cool down and discharge the material to obtain the viscoelastic amphoteric polymer. In step two, the preparation method of the amphoteric crosslinking agent includes the following steps: Step S1: Add 3-chloro-2-hydroxypropanesulfonic acid to acetone, purge with nitrogen, start stirring, and after a homogeneous reaction solution is formed, place it in an ice bath environment. Then, add functionalizing reagent and catalyst to the reaction solution. After the addition is complete, remove it from the ice bath and stir at 30-35℃ for 3-6 hours. Evaporate to remove the solvent, collect the product, and obtain the crosslinking agent intermediate material. Step S2: Add N-dodecyl-N,N-bis(2-hydroxyethyl)benzylammonium chloride and toluene to a nitrogen-filled reactor. After the addition is complete, stir and mix evenly. Then, add an alkaline hydroxide aqueous solution dropwise to the reactor. Stir at 50-60℃ for 1-2 hours. Then, add the crosslinking agent intermediate material to the reactor. After the addition is complete, raise the temperature to 80-90℃ and stir for 6-8 hours. Evaporate and remove the solvent, cool down and discharge the material to obtain the amphoteric crosslinking agent. In step S1, the functionalizing agent is acryloyl chloride or methacryloyl chloride; In step S1, the catalyst is pyridine or triethylamine.

2. The salt-sensitive viscoelastic gel modulator according to claim 1, characterized in that, In step one, the mass ratio of acrylamide, itaconic acid, deionized water, initiator, and amphoteric crosslinking agent is 20-30:2-4:60-80:0.1-0.3:1-2.

3. The salt-sensitive viscoelastic gel modulator according to claim 1, characterized in that, In step one, the initiator is a mixture of potassium persulfate and sodium sulfite in a mass ratio of 2-3:

1.

4. The salt-sensitive viscoelastic gel modulator according to claim 1, characterized in that, In step S2, the molar ratio of N-dodecyl-N,N-bis(2-hydroxyethyl)benzylammonium chloride and the crosslinking agent intermediate is 1:

2.

5. The salt-sensitive viscoelastic gel modifier according to claim 1, characterized in that, In step S2, the alkaline hydroxide aqueous solution is a sodium hydroxide aqueous solution or a potassium hydroxide aqueous solution, with a mass fraction of 10-20%.

6. A method for preparing a salt-sensitive viscoelastic gel modulator as described in claim 1, characterized in that, Includes the following steps: Step 1: Weigh out each ingredient according to the specified weight proportions and set aside. The second step is to add the viscoelastic amphoteric polymer, phenolic resin, and regulator into the mixer, control the stirring speed to 1000-2000 r / min, and mechanically mix for 10-30 minutes.

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