Preparation method of viscoelastic surfactant oil displacement plugging profile control agent

Abstract

The application discloses a kind of viscoelastic surfactant oil displacement plugging profile control agent preparation methods, it is related to oil exploitation chemical agent technical field, comprising the following steps: step one: raw material is weighed, and raw material is weighed according to percentage by weight: viscoelastic surfactant 5-15%, co-surfactant 2-8%, stabilizer 0.5-3%, salt additive 1-5%, and the balance is solvent;Step two: salt additive is dissolved, solvent is added to reaction container, is heated to 30-50 DEG C, under 300-500r / min stirring rate, salt additive is added, and is stirred 15-30min to completely dissolve.The prepared profile control agent can form stable worm-like micellar structure by raw material compounding optimization and step-by-step process control, has high viscoelasticity and strong plugging property, can still maintain good performance under 80-120 DEG C high temperature, 10000-20000mg / L high salinity reservoir conditions, solves the problem that traditional profile control agent is easily degraded, viscosity drops sharply under extreme reservoir environment, adapts to the profile control needs of various complex reservoirs.

Description

Technical Field

[0001] This invention relates to the field of oil extraction chemical agents, specifically to a method for preparing a viscoelastic surfactant oil displacement, plugging, and regulating agent. Background Technology

[0002] As oil extraction enters its middle and late stages, the water cut in the reservoir continues to rise, and the formation of high-permeability channels leads to severe cross-flow of the displacement fluid, resulting in a significant decrease in oil recovery. Modulation-driven oil recovery technology is a key means to improve this situation. Its core is to inject a modulation agent to block high-permeability channels, forcing the displacement fluid to redirect to low-permeability areas and increasing the utilization of remaining oil.

[0003] Viscoelastic surfactants, possessing both viscosity and elasticity, can form worm-like micelles through molecular self-assembly, exhibiting excellent rheological properties and blocking capabilities. However, existing preparation methods often suffer from drawbacks such as complex formulations, cumbersome processes, high costs, or insufficient temperature and salt resistance and poor stability of the modulators, limiting their industrial application. Therefore, developing a method for preparing viscoelastic surfactant modulators with simple formulations, convenient preparation processes, excellent temperature and salt resistance, and synergistic blocking and oil displacement effects has significant industrial application value. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing a viscoelastic surfactant oil displacement and plugging agent to solve the problems mentioned in the background art.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: A method for preparing a viscoelastic surfactant oil displacement, plugging, and regulating agent includes the following steps: Step 1: Weigh the raw materials. Weigh the raw materials by weight percentage as follows: viscoelastic surfactant 5-15%, co-surfactant 2-8%, stabilizer 0.5-3%, salt additives 1-5%, and the remainder is solvent. Step 2: Dissolve the salt additive. Add the solvent to the reaction vessel, heat to 30-50℃, add the salt additive at a stirring rate of 300-500r / min, and stir for 15-30min until completely dissolved. Step 3: Mix and disperse the surfactants, keep the temperature constant, add the viscoelastic surfactant and co-surfactant in sequence, adjust the stirring speed to 600-800 r / min, and stir for 40-60 min to form a uniform mixture; Step 4: Adding stabilizer and ultrasonic dispersion. Add stabilizer to the mixture, heat to 45-60℃, stir for 30-45 minutes, and then perform ultrasonic dispersion for 10-20 minutes.

[0006] Step 5: Cool the system to 25-35℃ and mature it for 2-4 hours at a stirring rate of 200-300r / min to obtain the target modulator.

[0007] A further improvement of the technical solution of the present invention is that: the viscoelastic surfactant is a compound of a cationic surfactant and an amphoteric surfactant, with a mass ratio of 1:0.5, wherein the cationic surfactant is selected from hexadecyltrimethylammonium chloride and octadecyltrimethylammonium bromide, and the amphoteric surfactant is selected from cocamidopropyl betaine.

[0008] A further improvement of the technical solution of the present invention is that the co-surfactant is selected from n-butanol, isoamyl alcohol, and ethylene glycol monobutyl ether, and the mass ratio of the co-surfactant to the viscoelastic surfactant is 1:2.

[0009] A further improvement of the technical solution of the present invention is that the stabilizer is selected from organosiloxane stabilizers and nano silica dispersions, with a particle size of 20-50 nm and a mass ratio of 0.8-2% in the system.

[0010] A further improvement of the technical solution of the present invention is that the salt additive is a compound of monovalent salt and divalent salt, wherein the monovalent salt is selected from sodium chloride and potassium chloride, and the divalent salt is selected from calcium chloride and magnesium chloride, and the mass ratio of the two is 1:0.3.

[0011] A further improvement of the technical solution of the present invention is that: the solvent is deionized water or simulated formation water, wherein the salinity of the simulated formation water is 5000-15000 mg / L, and the main ions include Na+. + K + Ca 2+ Mg 2+ Cl - SO4 2- .

[0012] A further improvement of the technical solution of the present invention is that step three further includes: adding the viscoelastic surfactant by dripping at a rate of 0.5-2 g / min, and continuously stirring during the dripping process.

[0013] A further improvement of the technical solution of the present invention is that step four further includes: the power of ultrasonic dispersion treatment is 150-300W, the ultrasonic frequency is 20-40kHz, and the system temperature is kept stable at 45-60℃ during the ultrasonic process.

[0014] A further improvement of the technical solution of the present invention is that step five further includes: the curing process is carried out under nitrogen protection, with a nitrogen flow rate of 0.1-0.3 L / min, in order to inhibit the oxidative degradation of the surfactant.

[0015] A further improvement of the technical solution of the present invention is that the prepared modulator has the following properties under the conditions of 80-120℃ and mineralization of 10000-20000mg / L: apparent viscosity ≥40mPa・s, plugging rate ≥85% in core displacement experiment, oil displacement efficiency is 15-25 percentage points higher than water drive, and viscosity retention rate ≥80% after standing for 30 days under the above conditions.

[0016] Due to the adoption of the above technical solution, the technical progress achieved by this invention compared to the prior art is as follows: 1. This invention provides a method for preparing a viscoelastic surfactant-based oil displacement and plugging modifier. Through raw material compounding optimization and step-by-step process control, the prepared modifier can form a stable worm-like micelle structure, possessing both high viscoelasticity and strong plugging properties. It can maintain good performance even under high temperature conditions of 80-120℃ and high salinity reservoir conditions of 10000-20000mg / L, solving the problem of easy degradation and sudden viscosity drop of traditional modifiers in extreme reservoir environments, and adapting to the modifier needs of various complex reservoirs.

[0017] 2. This invention provides a method for preparing a viscoelastic surfactant-based oil displacement and plugging agent. The raw materials used are conventional cationic surfactants, amphoteric surfactants, low-carbon alcohol co-surfactants, and inorganic salts. By optimizing the ratio, the amount of high-end additives is reduced, the process steps are simplified and the production cycle is shortened, and the overall cost is reduced by 10-15% compared with the existing viscoelastic surfactant-based oil displacement agent preparation technology. At the same time, the oil displacement efficiency is increased by 15-25 percentage points compared with water drive, which significantly improves the economic benefits of oil extraction.

[0018] 3. This invention provides a method for preparing a viscoelastic surfactant-based oil displacement and plugging modifier. The selected raw materials, betaine-based amphoteric surfactants and lignin sulfonate stabilizers, have good biodegradability and generate no toxic or harmful byproducts. The preparation process does not require high temperature, high pressure, or highly corrosive reagents, ensuring high safety for production equipment and operators. Furthermore, the modifier leaves no residual pollution in the formation, meeting the industry development needs of green mining. Attached Figure Description

[0019] Figure 1 This is a flowchart of the steps of the present invention; Figure 2 This is a flowchart illustrating the formulation of the viscoelastic surfactant of the present invention. Figure 3 This is a flowchart illustrating the formulation of the salt additives of the present invention. Figure 4 This is a flowchart illustrating the formulation of the co-surfactant of the present invention. Figure 5 This is a diagram showing the ionic composition of the present invention. Detailed Implementation

[0020] The present invention will be further described in detail below with reference to embodiments: like Figure 1-5 As shown, the present invention has the following three specific embodiments.

[0021] Example 1 Raw material ratio: 8% hexadecyltrimethylammonium chloride, 4% cocamidopropyl betaine, 3% n-butanol, 1% organosiloxane stabilizer, 2% sodium chloride, 0.5% calcium chloride, and 1.5% deionized water.

[0022] Preparation steps: S1: Add deionized water to the reactor, heat to 35°C, add sodium chloride and calcium chloride while stirring at 350 r / min, and stir for 20 min until completely dissolved; S2: Keep at 35℃, add hexadecyltrimethylammonium chloride and cocamidopropyl betaine, stir at 700r / min for 50min to form a uniform mixture; S3: Add organosiloxane stabilizer, heat to 50℃, continue stirring for 40 min, then ultrasonically disperse at 300W for 15 min; S4: Cool to 30℃, stir and mature at 250r / min for 3h to obtain the finished product of the driving agent.

[0023] Example 2 Raw material ratio: 10% octadecyltrimethylammonium bromide, 5% lauramide propyl hydroxysulfonate betaine, 4% ethylene glycol monobutyl ether, 1.5% lignin sulfonate stabilizer, 3% potassium chloride, 1% calcium chloride, and 75.5% deionized water.

[0024] Preparation steps: S1: Heat deionized water to 40℃, add potassium chloride and calcium chloride while stirring at 400r / min, and stir for 25min to dissolve; S2: Add octadecyltrimethylammonium bromide and lauramide propyl hydroxysulfonate betaine, stir at 750 r / min for 55 min; S3: Add lignin sulfonate stabilizer, heat to 55℃, stir for 35 min, and then ultrasonically disperse at 250W for 18 min; S4: Cool to 32℃, mature at 280r / min for 3.5h to obtain the finished product.

[0025] Performance testing: At 100℃ and a salinity of 18000mg / L, the apparent viscosity was 56mPa・s, the plugging rate was 86%, and the oil displacement efficiency was improved by 22 percentage points compared with water drive.

[0026] like Figure 1-5 As shown, Example 3 Raw material ratio: 6% hexadecyltrimethylammonium chloride, 4% octadecyltrimethylammonium bromide, 3% cocamidopropyl betaine, 2% isoamyl alcohol, 0.8% organosiloxane stabilizer, 2% sodium chloride, and 82.2% deionized water.

[0027] Preparation steps: S1: Heat deionized water to 38℃, add sodium chloride while stirring at 380r / min, and stir for 18min to dissolve; S2: Add the mixed surfactant and stir at 650 rpm for 45 minutes; S3: Add isoamyl alcohol and stabilizer, heat to 48℃, stir for 38 min, then ultrasonically disperse at 200W for 12 min; S4: Cool to 28℃, mature at 220r / min for 2.5h to obtain the finished product.

[0028] Performance testing: At 80℃ and a mineralization of 5000 mg / L, the apparent viscosity was 72 mPa·s, the plugging rate was 90%, and the oil displacement efficiency was improved by 16 percentage points compared with water drive.

[0029] In this invention, all three sets of examples strictly follow the step-by-step process of "raw material weighing - salt dissolution - surfactant mixing - stabilizer addition and ultrasonic dispersion - cooling and maturation". The performance data of the products in the examples fully demonstrate that the temperature resistance range covers 25-100℃, the salinity resistance covers 5000-18000mg / L, which is suitable for medium-high temperature and medium-high salinity reservoirs. The apparent viscosity is 56-72mPa・s, the plugging rate is 86-90%, and the oil displacement efficiency is 16-22 percentage points higher than that of water drive. All of them meet the core performance requirements of industrial blending and driving, and the product performance does not fluctuate significantly under different ratios.

[0030] The present invention has been described in detail above. However, modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, any modifications or improvements that do not depart from the spirit of the present invention are within the scope of protection of the present invention.

Claims

1. A method for preparing a viscoelastic surfactant-based oil displacement, plugging, and regulating agent, characterized in that: Includes the following steps: Step 1: Weigh the raw materials. Weigh the raw materials by weight percentage as follows: viscoelastic surfactant 5-15%, co-surfactant 2-8%, stabilizer 0.5-3%, salt additives 1-5%, and the remainder is solvent. Step 2: Dissolve the salt additive. Add the solvent to the reaction vessel, heat to 30-50℃, add the salt additive at a stirring rate of 300-500r / min, and stir for 15-30min until completely dissolved. Step 3: Mix and disperse the surfactants, keep the temperature constant, add the viscoelastic surfactant and co-surfactant in sequence, adjust the stirring speed to 600-800 r / min, and stir for 40-60 min to form a uniform mixture; Step 4: Adding stabilizer and ultrasonic dispersion. Add stabilizer to the mixture, heat to 45-60℃, stir for 30-45 minutes, and then perform ultrasonic dispersion for 10-20 minutes. Step 5: Cool the system to 25-35℃ and mature it for 2-4 hours at a stirring rate of 200-300r / min to obtain the target modulator.

2. The method for preparing a viscoelastic surfactant oil displacement, plugging, and regulating agent according to claim 1, characterized in that: The viscoelastic surfactant is a compound of a cationic surfactant and an amphoteric surfactant in a mass ratio of 1:0.

5. The cationic surfactant is selected from hexadecyltrimethylammonium chloride and octadecyltrimethylammonium bromide, and the amphoteric surfactant is selected from cocamidopropyl betaine.

3. The method for preparing a viscoelastic surfactant oil displacement, plugging, and regulating agent according to claim 1, characterized in that: The co-surfactant is selected from n-butanol, isoamyl alcohol, and ethylene glycol monobutyl ether, and the mass ratio of the co-surfactant to the viscoelastic surfactant is 1:

2.

4. The method for preparing a viscoelastic surfactant oil displacement, plugging, and regulating agent according to claim 1, characterized in that: The stabilizer is selected from organosiloxane stabilizers and nano-silica dispersions, with a particle size of 20-50 nm and a mass percentage of 0.8-2% in the system.

5. The method for preparing a viscoelastic surfactant oil displacement, plugging, and regulating agent according to claim 1, characterized in that: The salt additive is a compound of monovalent and divalent salts, wherein the monovalent salts are selected from sodium chloride and potassium chloride, and the divalent salts are selected from calcium chloride and magnesium chloride, with a mass ratio of 1:0.

3.

6. The method for preparing a viscoelastic surfactant oil displacement, plugging, and regulating agent according to claim 1, characterized in that: The solvent is deionized water or simulated formation water, wherein the simulated formation water has a salinity of 5000-15000 mg / L and the main ions include Na+. + K + Ca 2+ Mg 2+ Cl - SO4 2- .

7. The method for preparing a viscoelastic surfactant oil displacement, plugging, and regulating agent according to claim 1, characterized in that: Step three also includes: adding the viscoelastic surfactant by dropping it at a rate of 0.5-2 g / min, and stirring continuously during the dropping process.

8. The method for preparing a viscoelastic surfactant oil displacement, plugging, and regulating agent according to claim 1, characterized in that: Step four also includes: the ultrasonic dispersion treatment power is 150-300W, the ultrasonic frequency is 20-40kHz, and the system temperature is kept stable at 45-60℃ during the ultrasonic process.

9. The method for preparing a viscoelastic surfactant oil displacement, plugging, and regulating agent according to claim 1, characterized in that: Step five further includes: the curing process is carried out under nitrogen protection, with a nitrogen flow rate of 0.1-0.3 L / min, to inhibit the oxidative degradation of the surfactant.

10. The method for preparing a viscoelastic surfactant oil displacement, plugging, and regulating agent according to claim 1, characterized in that: The prepared modulator has the following properties under the conditions of 80-120℃ and 10000-20000mg / L: apparent viscosity ≥40mPa・s, plugging rate ≥85% in core displacement experiment, oil displacement efficiency 15-25 percentage points higher than water drive, and viscosity retention rate ≥80% after standing for 30 days under the above conditions.

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