Viscosity-reducing oil displacement agent for viscosity-reducing composite flooding of common heavy oil reservoir and preparation method and application thereof
阅读说明：本技术 普通稠油油藏降粘复合驱用降粘驱油剂及其制备方法和应用 (Viscosity-reducing oil displacement agent for viscosity-reducing composite flooding of common heavy oil reservoir and preparation method and application thereof ) 是由 姜力华 祝东明 秦玉斌 齐高政 丁锡刚 吴庆凯 李金平 胡朋朋 于 2021-08-27 设计创作，主要内容包括：本发明提出一种普通稠油油藏降粘复合驱用降粘驱油剂及其制备方法和应用,属于油田化学领域。本发明提供的普通稠油油藏降粘复合驱用降粘驱油剂,以质量百分比计,包括纳米降粘剂30％-40％、异丙醇酰胺10％-20％、咪唑啉5％-10％、低碳醇10％,其余为水。本发明提供的降粘驱油剂主要应用于普通稠油油藏降粘复合驱中,通过与聚合物复配,发挥了降粘化学驱和聚合物驱的双重作用,既能降粘洗油,又能扩大波及体积,可有效提高普通稠油油藏的采收率。(The invention provides a viscosity-reducing oil displacement agent for viscosity-reducing combined flooding of a common heavy oil reservoir and a preparation method and application thereof, belonging to the field of oilfield chemistry. The viscosity-reducing oil displacement agent for viscosity-reducing composite flooding of the common heavy oil reservoir comprises, by mass, 30-40% of a nano viscosity-reducing agent, 10-20% of isopropanolamide, 5-10% of imidazoline, 10% of low-carbon alcohol and the balance water. The viscosity-reducing oil displacement agent provided by the invention is mainly applied to viscosity-reducing composite flooding of a common heavy oil reservoir, and can play double roles of viscosity-reducing chemical flooding and polymer flooding by compounding with a polymer, so that the viscosity-reducing oil displacement agent can reduce viscosity and wash oil, expand swept volume and effectively improve the recovery ratio of the common heavy oil reservoir.)
1. The viscosity reduction oil displacement agent for viscosity reduction composite flooding of the common heavy oil reservoir is characterized by comprising 30-40% of a nano viscosity reducer, 10-20% of isopropanolamide, 5-10% of imidazoline, 10% of low-carbon alcohol and the balance of water in percentage by mass.
2. The viscosity-reducing oil-displacing agent according to claim 1, wherein the nano viscosity-reducing agent is a nano viscosity-reducing agent with a code number of VR-WX302S, commercially available from Ningbo nano technologies GmbH, and has a particle size of 200nm or less.
3. The viscosity-reducing oil-displacing agent according to claim 1, wherein the isopropanolamide is selected from isopropanolamide 6508, which has a chemical formula of C11H43CON(CH2CH2OH)2。
4. Viscosity reducing oil-displacing agent according to claim 1, wherein the imidazoline is selected from coco hydroxyethyl imidazoline of formula C5H10N2O。
5. The viscosity-reducing oil-displacing agent according to claim 1, wherein the lower alcohol is at least one of ethanol and isopropanol.
6. The preparation method of the viscosity-reducing oil displacement agent for the viscosity-reducing compound flooding of the common heavy oil reservoir according to any one of claims 1 to 5, which is characterized by comprising the following steps of:
adding the water amount required by the preparation of the viscosity-reducing oil displacement agent into a reaction kettle, adding isopropanol amide, imidazoline and low-carbon alcohol at the temperature of 40-50 ℃, uniformly stirring, adding the nano viscosity reducer, and fully and uniformly stirring to obtain the viscosity-reducing oil displacement agent for the viscosity-reducing composite flooding of the common heavy oil reservoir.
7. The application of the viscosity-reducing oil displacement agent for the viscosity-reducing compound flooding of the common heavy oil reservoir according to any one of claims 1 to 5 in the viscosity-reducing compound flooding of the common heavy oil reservoir, wherein the salinity of formation water is 0-500000mg/L, and the concentration of calcium and magnesium ions is less than or equal to 1000 mg/L.
8. The use of claim 7, wherein the viscosity-reducing oil displacement agent is used at a concentration of 0.3% when used alone or in combination with a polymer at a concentration of 0.2%.
9. The use of claim 8, wherein the viscosity-reducing oil-displacing agent has a degree of mineralization of 50000mg/L, and calcium in the viscosity-reducing oil-displacing agentWhen the magnesium ion concentration is 1000mg/L, the viscosity reduction rate after adsorption is more than or equal to 96.5 percent and the interfacial tension after adsorption is less than or equal to 3.8 multiplied by 10 when the magnesium ion concentration is compatible with the water phase-2mN/m, and the natural settling dehydration rate is more than or equal to 95.7 percent.
10. The application of claim 8, wherein the viscosity reduction oil displacement agent has a viscosity reduction rate of 86.5% or more and an interfacial tension of 3.6 x 10 or less when measured at 70 ℃ after being compatible with a polymer-2mN/m, the viscosity retention rate is more than or equal to 100.8 percent; and the viscosity reduction rate is more than or equal to 95.2 percent after 30 days of thermal stability under the anaerobic condition; the oil washing rate is more than or equal to 56.3 percent.
Technical Field
The invention belongs to the field of oilfield chemistry, and particularly relates to a viscosity-reducing oil displacement agent for viscosity-reducing composite flooding of a common heavy oil reservoir, and a preparation method and application thereof.
Background
In recent years, the technology for improving the recovery efficiency of the chemical cold recovery of the thick oil is paid more and more attention, and the viscosity reduction compound flooding technology for displacing the thick oil by using a flooding system consisting of a polymer and a water-soluble viscosity reduction oil displacement agent is an important research direction.
The polymer is mature in chemical flooding, and can play a role in profile control and flooding by increasing the viscosity of a water phase and reducing the water-oil fluidity ratio, thereby enlarging swept volume and further improving the recovery ratio. The viscosity reduction composite flooding technology is to reasonably optimize and combine the viscosity reduction oil displacement agent to generate a synergistic effect.
Patent CN107365574A discloses a viscosity-reducing oil-displacing agent, which uses alkyl alcohol polyoxyethylene ether sulfate as a main surfactant, uses a nonionic surfactant, an anionic surfactant, an organic solvent and sodium chloride as auxiliaries, and forms a composite oil-displacing system with polyacrylamide polymers, so that the sweep can be enlarged, the oil-displacing efficiency can be improved, and the recovery ratio of a common heavy oil reservoir can be effectively improved. The main agent of the formula of the patent, namely the alkyl alcohol polyoxyethylene ether sulfate, can be hydrolyzed and failed at the formation temperature of more than 50 ℃, and is not suitable for oil reservoirs with the formation temperature of more than 50 ℃. Patent CN107365575A discloses a viscosity-reducing oil-displacing agent and an oil-displacing system suitable for heavy oil reservoirs, wherein the viscosity-reducing oil-displacing agent is composed of an emulsifier, an ester compound, a wetting agent and water, and is used in cooperation with a polymer, so that the oil-displacing efficiency can be effectively improved, and the recovery ratio of heavy oil is improved. But only the oil displacement efficiency index of the system in indoor evaluation is mentioned, and other indexes which can influence the field use effect are not mentioned.
The influence factors of the viscosity-reducing compound flooding technology for the heavy oil are complex, the limiting conditions are multiple, the compatibility with the polymer, the stratum rock adsorption resistance and the thermal stability need to be investigated, and some conventional indexes such as interfacial tension, viscosity-reducing rate, natural settling dehydration rate, oil washing rate and the like need to be investigated, so that the viscosity-reducing oil-displacing agent suitable for the viscosity-reducing compound flooding of the common heavy oil reservoir needs to be developed urgently.
Disclosure of Invention
The viscosity-reducing oil displacement agent can be effectively applied to viscosity-reducing compound flooding of common heavy oil reservoirs, the salinity of stratum water is less than or equal to 50000mg/L, and the concentration of calcium and magnesium ions is less than or equal to 1000mg/L, and the preparation process is simple, low in cost and environment-friendly.
In order to achieve the purpose, the invention provides a viscosity-reducing oil displacement agent for viscosity-reducing composite flooding of a common heavy oil reservoir, which comprises 30-40% of a nano viscosity-reducing agent, 10-20% of isopropanolamide, 5-10% of imidazoline, 10% of low-carbon alcohol and the balance of water in percentage by mass.
Preferably, the nano viscosity reducer is a nano viscosity reducer with the code of VR-WX302S, which is commercially available from Ningbo nano science and technology Limited company, and the particle size is less than or equal to 200 nm. The nano viscosity reducer has good injectability and has the characteristics of temperature resistance and salt resistance.
Preferably, the isopropanol amide is selected from 6508, which is used as a novel surfactant and has a chemical formula of C11H43CON(CH2CH2OH)2. The selected isopropanolamide 6508 is similar to ethanolamine in structure, and thus has the features of non-ionic surfactant, excellent detergency, permeability, oil stain dispersivity, high calcium and magnesium resistance and high compatibility with other surfactant. It is understood that the isopropanolamide 6508 is currently a commercially available product, the manufacturer being hamm, germany.
Preferably, the imidazoline is coco hydroxyethyl imidazoline, having formula C5H10N2And O. It is understood that cocoyl hydroxyethyl imidazoline has excellent emulsifying, dispersing and solubilizing properties.
Preferably, the lower alcohol is at least one of ethanol and isopropanol.
The invention provides a preparation method of a viscosity-reducing oil displacement agent for viscosity-reducing composite flooding of a common heavy oil reservoir according to any one of the technical schemes, which comprises the following steps:
adding the water amount required by the preparation of the viscosity-reducing oil displacement agent into a reaction kettle, adding isopropanol amide, imidazoline and low-carbon alcohol at the temperature of 40-50 ℃, uniformly stirring, adding the nano viscosity reducer, and fully and uniformly stirring to obtain the viscosity-reducing oil displacement agent for the viscosity-reducing composite flooding of the common heavy oil reservoir.
The invention provides an application of the viscosity-reducing oil-displacing agent for viscosity-reducing composite flooding of a common heavy oil reservoir according to any one of the technical schemes in viscosity-reducing composite flooding of the common heavy oil reservoir, wherein the salinity of formation water is less than or equal to 500000mg/L, and the concentration of calcium and magnesium ions is less than or equal to 1000 mg/L.
Preferably, the viscosity-reducing oil displacement agent is used at a concentration of 0.3% when used alone or used together with a polymer with a concentration of 0.2%.
Preferably, when the viscosity-reducing oil-displacing agent is compatible with a water phase with the mineralization degree of 50000mg/L and the calcium and magnesium ion concentration of 1000mg/L, the viscosity-reducing rate after adsorption is more than or equal to 96.5 percent measured at 70 ℃, and the interfacial tension after adsorption is less than or equal to 3.8 multiplied by 10-2mN/m, and the natural settling dehydration rate is more than or equal to 95.7 percent.
Preferably, after the viscosity-reducing oil displacement agent is compatible with the polymer, the viscosity-reducing rate is more than or equal to 86.5 percent and the interfacial tension is less than or equal to 3.6 multiplied by 10 when the viscosity-reducing oil displacement agent is measured at 70 DEG C-2mN/m, the viscosity retention rate is more than or equal to 100.8 percent; and the viscosity reduction rate is more than or equal to 95.2 percent after 30 days of thermal stability under the anaerobic condition; the oil washing rate is more than or equal to 56.3 percent.
Compared with the prior art, the invention has the advantages and positive effects that:
1. the invention provides a viscosity-reducing oil-displacing agent for viscosity-reducing composite flooding of a common heavy oil reservoir, which is mainly prepared by compounding a nano viscosity-reducing agent, isopropanolamide and imidazoline. The nano viscosity reducer has strong surface activity, oil washing capacity and emulsification viscosity reduction capacity, and can remarkably reduce the oil-water interfacial tension and improve the oil washing capacity after being compounded with the isopropanolamide; imidazoline has excellent emulsifying, dispersing and solubilizing performances, and can effectively improve the adsorptivity of a system in a stratum, further reduce the oil-water interfacial tension and the viscosity reduction capability on thick oil by adding the imidazoline.
2. The viscosity-reducing oil displacement agent provided by the invention is mainly applied to viscosity-reducing composite flooding of a common heavy oil reservoir, and can play double roles of viscosity-reducing chemical flooding and polymer flooding by compounding with a polymer, so that the viscosity-reducing oil displacement agent can reduce viscosity and wash oil, expand swept volume and effectively improve the recovery ratio of the common heavy oil reservoir.
3. The viscosity-reducing oil displacement agent provided by the invention has the advantages of strong adsorption resistance, good thermal stability, high oil washing rate and good compatibility with polymers, and can increase the viscosity of the polymers.
4. The viscosity-reducing oil displacement agent for common viscosity-reducing composite flooding of the heavy oil reservoir has the advantages of simple production process, easily purchased raw materials, no harm to the environment and personnel from production to use and accordance with the requirements of environmental protection.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Example 1
Adding 300kg of water into a reaction kettle, controlling the temperature to be 40 ℃, adding 200kg of isopropanolamide, 100kg of cocoyl hydroxyethyl imidazoline and 100kg of ethanol, uniformly stirring, adding 300kg of nano viscosity reducer VR-WX302S, and fully and uniformly stirring to obtain the viscosity-reducing oil displacement agent for the viscosity-reducing composite flooding of the common heavy oil reservoir.
Example 2
Adding 310kg of water into a reaction kettle, controlling the temperature to be 42 ℃, adding 180kg of isopropanol amide, 90kg of cocoyl hydroxyethyl imidazoline and 100kg of isopropanol, uniformly stirring, adding 320kg of nano viscosity reducer VR-WX302S, and fully and uniformly stirring to obtain the viscosity-reducing oil displacement agent for the viscosity-reducing composite flooding of the common heavy oil reservoir.
Example 3
Adding 320kg of water into a reaction kettle, controlling the temperature to be 44 ℃, adding 160kg of isopropanolamide, 80kg of cocoyl hydroxyethyl imidazoline and 100kg of ethanol, uniformly stirring, adding 340kg of nano viscosity reducer VR-WX302S, and fully and uniformly stirring to obtain the viscosity-reducing oil displacement agent for the viscosity-reducing composite flooding of the common heavy oil reservoir.
Example 4
Adding 330kg of water into a reaction kettle, controlling the temperature to be 46 ℃, adding 140kg of isopropanol amide, 70kg of cocoyl hydroxyethyl imidazoline and 100kg of isopropanol, stirring uniformly, adding 360kg of nano viscosity reducer VR-WX302S, and fully stirring uniformly to obtain the viscosity-reducing oil displacement agent for the viscosity-reducing composite flooding of the common heavy oil reservoir.
Example 5
Adding 340kg of water into a reaction kettle, controlling the temperature to be 48 ℃, adding 120kg of isopropanolamide, 60kg of cocoyl hydroxyethyl imidazoline, 50kg of ethanol and 50kg of isopropanol, stirring uniformly, adding 380kg of nano viscosity reducer VR-WX302S, and stirring uniformly to obtain the viscosity reduction oil displacement agent for the viscosity reduction composite flooding of the common heavy oil reservoir.
Example 6
Adding 350kg of water into a reaction kettle, controlling the temperature to be 50 ℃, adding 100kg of isopropanolamide, 50kg of cocoyl hydroxyethyl imidazoline, 50kg of ethanol and 50kg of isopropanol, stirring uniformly, adding 400kg of nano viscosity reducer VR-WX302S, and stirring uniformly to obtain the viscosity-reducing oil displacement agent for the viscosity-reducing composite flooding of the common heavy oil reservoir.
The viscosity-reducing oil displacement agent for viscosity-reducing combined flooding of the common heavy oil reservoir, provided by the invention, has the components and the proportion determined on the basis of a large number of experiments, and any change can cause unqualified detection indexes.
Comparative example 1
Adding 500kg of water into a reaction kettle, controlling the temperature to be 40 ℃, adding 100kg of cocoyl hydroxyethyl imidazoline and 100kg of ethanol, uniformly stirring, adding 300kg of nano viscosity reducer VR-WX302S, and fully and uniformly stirring to obtain the viscosity reduction oil displacement agent for the viscosity reduction composite flooding of the common heavy oil reservoir.
Comparative example 1 is a viscosity reduction oil displacement agent for ordinary heavy oil reservoir viscosity reduction composite flooding obtained by removing the isopropanolamide in the formula of example 1, the quantity of the isopropanolamide is supplemented by water, and the detection does not reach the standard according to the index requirement.
Comparative example 2
Adding 400kg of water into a reaction kettle, controlling the temperature to be 40 ℃, adding 200kg of isopropanolamide and 100kg of ethanol, uniformly stirring, adding 300kg of nano viscosity reducer VR-WX302S, and fully and uniformly stirring to obtain the viscosity-reducing oil displacement agent for the common heavy oil reservoir viscosity-reducing composite flooding.
Comparative example 2 is a viscosity reduction oil displacement agent for ordinary heavy oil reservoir viscosity reduction composite flooding obtained by removing cocoyl hydroxyethyl imidazoline in the formula of example 1, the amount of cocoyl hydroxyethyl imidazoline is supplemented with water, and the detection does not reach the standard according to the index requirement.
Comparative example 3
Adding 600kg of water into a reaction kettle, controlling the temperature to be 40 ℃, adding 200kg of isopropanolamide, 100kg of cocoyl hydroxyethyl imidazoline and 100kg of ethanol, and fully and uniformly stirring to obtain the viscosity-reducing oil displacement agent for the viscosity-reducing composite flooding of the common heavy oil reservoir.
Comparative example 3 is the viscosity reduction oil displacement agent for viscosity reduction compound flooding of the common heavy oil reservoir obtained by removing the nano viscosity reducer VR-WX302S in the formula of example 1, the amount of the nano viscosity reducer VR-WX302S is filled with water, and the detection does not reach the standard according to the index requirement.
Comparative example 4
Adding 410kg of water into a reaction kettle, controlling the temperature to be 40 ℃, adding 90kg of isopropanolamide, 100kg of cocoyl hydroxyethyl imidazoline and 100kg of ethanol, uniformly stirring, adding 300kg of nano viscosity reducer VR-WX302S, and fully and uniformly stirring to obtain the viscosity-reducing oil displacement agent for the viscosity-reducing composite flooding of the common heavy oil reservoir.
Comparative example 4 is that the isopropanolamide in the formula of example 1 deviates from the range of 10-20%, namely 90kg of isopropanolamide (9%) is added to obtain the viscosity-reducing oil-displacing agent for viscosity-reducing composite flooding of the common heavy oil reservoir, the amount of the less-added isopropanolamide is supplemented by water, and the detection does not reach the standard according to the index requirements.
Comparative example 5
Adding 290kg of water into a reaction kettle, controlling the temperature to be 40 ℃, adding 210kg of isopropanolamide, 100kg of cocoyl hydroxyethyl imidazoline and 100kg of ethanol, uniformly stirring, adding 300kg of nano viscosity reducer VR-WX302S, and fully and uniformly stirring to obtain the viscosity-reducing oil displacement agent for the viscosity-reducing composite flooding of the common heavy oil reservoir.
Comparative example 5 is that the isopropanolamide in the formula of example 1 deviates from the range of 10-20%, namely 210kg of isopropanolamide (21%) is added to obtain the viscosity-reducing oil-displacing agent for viscosity-reducing composite flooding of the common heavy oil reservoir, the excessive quantity of the isopropanolamide is removed from water, and the detection does not reach the standard according to the index requirement.
Comparative example 6
Adding 360kg of water into a reaction kettle, controlling the temperature to be 40 ℃, adding 200kg of isopropanolamide, 40kg of cocoyl hydroxyethyl imidazoline and 100kg of ethanol, uniformly stirring, adding 300kg of nano viscosity reducer VR-WX302S, and fully and uniformly stirring to obtain the viscosity-reducing oil displacement agent for the viscosity-reducing composite flooding of the common heavy oil reservoir.
Comparative example 6 shows that cocoyl hydroxyethyl imidazoline in the formula of example 1 deviates from the range of 5% -10%, namely 40kg of cocoyl hydroxyethyl imidazoline (4%) is added to obtain the viscosity reduction oil displacement agent for viscosity reduction composite flooding of the common heavy oil reservoir, the amount of the added cocoyl hydroxyethyl imidazoline is supplemented with water, and the detection does not reach the standard according to the index requirements.
Comparative example 7
Adding 290kg of water into a reaction kettle, controlling the temperature to be 40 ℃, adding 200kg of isopropanolamide, 110kg of cocoyl hydroxyethyl imidazoline and 100kg of ethanol, uniformly stirring, adding 300kg of nano viscosity reducer VR-WX302S, and fully and uniformly stirring to obtain the viscosity-reducing oil displacement agent for the viscosity-reducing composite flooding of the common heavy oil reservoir.
Comparative example 7 shows that cocoyl hydroxyethyl imidazoline in the formula of example 1 deviates from the range of 5% -10%, namely 110kg of cocoyl hydroxyethyl imidazoline (11%) is added to obtain the viscosity reduction oil displacement agent for viscosity reduction composite flooding of the common heavy oil reservoir, the amount of the added cocoyl hydroxyethyl imidazoline is removed from water, and the detection does not reach the standard according to the index requirement.
Comparative example 8
Adding 310kg of water into a reaction kettle, controlling the temperature to be 40 ℃, adding 200kg of isopropanolamide, 100kg of cocoyl hydroxyethyl imidazoline and 100kg of ethanol, uniformly stirring, adding 290kg of nano viscosity reducer VR-WX302S, and fully and uniformly stirring to obtain the viscosity-reducing oil displacement agent for the viscosity-reducing composite flooding of the common heavy oil reservoir.
Comparative example 8 shows that the nano viscosity reducer VR-WX302S in the formula of example 1 deviates from the range of 30-40%, namely that 290kg of nano viscosity reducer VR-WX302S (29%) is added to obtain the viscosity reduction oil displacement agent for common heavy oil reservoir viscosity reduction composite flooding, the amount of the nano viscosity reducer VR-WX302S which is less added is supplemented with water, and the detection does not reach the standard according to the index requirement.
Comparative example 9
Adding 190kg of water into a reaction kettle, controlling the temperature to be 40 ℃, adding 200kg of isopropanolamide, 100kg of cocoyl hydroxyethyl imidazoline and 100kg of ethanol, uniformly stirring, adding 410kg of nano viscosity reducer VR-WX302S, and fully and uniformly stirring to obtain the viscosity-reducing oil displacement agent for the viscosity-reducing composite flooding of the common heavy oil reservoir.
Comparative example 9 is that the nano viscosity reducer VR-WX302S in the formulation of example 1 deviates from the range of 30-40%, namely, 410kg of nano viscosity reducer VR-WX302S (41%) is added to obtain the viscosity reduction oil displacement agent for viscosity reduction composite flooding of the common heavy oil reservoir, the amount of the added nano viscosity reducer VR-WX302S is removed from water, and the detection does not reach the standard according to the index requirement.
The products prepared in the above examples and comparative examples are prepared to 0.3% concentration for performance test, and the test conditions and test method are as follows:
and (3) testing conditions are as follows:
1. the apparatus used was tested as follows: the system comprises a Bohler flying DV3T rheometer, a constant-temperature drying box, a TX-500C type full-range rotary drop interfacial tension measuring instrument, a constant-temperature water bath oscillator, an electronic balance and a vertical stirrer;
2. the following tests determine the temperature: the formation temperature of a certain area of the oil field is 70 ℃;
3. crude oil for testing: a block of dehydrated crude oil (viscosity 965mpa.s at 70 ℃) in a victory oil field;
4. test water: water is injected into a certain block of the Shengli oil field, the mineralization degree is 50000mg/L, and the concentration of calcium and magnesium ions is 1000 mg/L.
The test method comprises the following steps:
1. anti-adsorption test
1.1 weighing 30.0g of simulated formation sand, putting the sand into a screw reagent bottle, adding 90.0g of sample solution with the concentration of 0.3%, screwing a cover, shaking up by hand, putting the sand into a constant-temperature water bath oscillator, setting the oscillation frequency to be 170r/min, and oscillating for 24 hours at the oil reservoir temperature.
1.2 taking out a sample, standing for 60min, sucking 30.0g of supernatant by using an injector, putting the supernatant into a 250mL beaker, adding 70.0g of experimental oil sample, sealing, putting the beaker into a constant-temperature drying oven, and keeping the temperature at 70 ℃ for 2 h.
1.3 taking out the oil-water mixture, stirring with glass rod to mix oil and water uniformly, pouring into the measuring cylinder of rotary viscometer rapidly, and setting the shear rate at 60s-1And measuring the viscosity of the oil-water mixed liquid at the oil reservoir temperature.
1.4 viscosity reduction rate was calculated according to formula (1):
in the formula: f-viscosity reduction rate;
μ0-viscosity of the thick oil sample at 70 ℃, mPa · s;
mu-viscosity, mPas of the oil-water mixture at 70 ℃.
1.5 interfacial tension between the adsorbed sample solution and the experimental oil sample was measured at reservoir temperature as specified in SY/T5370-2018, 7.5.
2. Test of dehydration rate by natural sedimentation
2.1 Take 9mL of post-adsorption supernatant into a 50mL stoppered cylinder, thermostatted at reservoir temperature for 1h, and read the volume of the lower aqueous phase of the cylinder (to the nearest 0.1 mL).
2.2 adding 21.0mL of experimental oil sample into the measuring cylinder with the plug, screwing, placing in a constant-temperature drying box, and keeping the temperature constant for 1h at the oil reservoir temperature. And taking out the measuring cylinder, shaking the measuring cylinder up and down to fully mix the oil and the water, placing the measuring cylinder in a constant-temperature drying box, standing the measuring cylinder for 1 hour at the oil reservoir temperature, and reading the water outlet volume (accurate to 0.1mL) at the lower part of the measuring cylinder.
2.3 the natural settling dehydration rate is calculated according to the formula (1):
in the formula: x is the natural settling dehydration rate, and is expressed by percentage;
V0the water content of the oil-water mixture is in milliliters (mL);
v is the volume of the effluent after the oil-water mixed solution is kept stand for 1h, and the unit is milliliter (mL).
3. Compatibility test with Polymer
3.1 preparation of mother liquor of polymer (commercially available from environment engineering Co., Ltd., Dongyingbao mo, in particular, polyacrylamide for oil displacement, type I): accurately weigh (1/S) g of dry polymer powder (S is solid content) to the nearest 0.0001 g. Weighing (200-1/S) g of yellow river water in a 500mL beaker, starting a vertical stirrer, slowly adding the polymer dry powder along the vortex wall within 1min at the speed of (400 +/-20) r/min, regulating the stirring speed to (500 +/-20) r/min, and continuously stirring for 2h to obtain the polymer mother liquor with the concentration of 0.5%. After standing at room temperature for 24 hours, the mixture was stirred slightly with a glass rod for further use.
3.2 preparation of Single Polymer solution: 20.0g of the polymer mother liquor was added to a 100mL beaker, 30.0g of brine was added, and the mixture was stirred on a magnetic stirrer at a rotational speed of 300r/min for 30min to obtain a single polymer solution with a concentration of 0.2%.
3.3 preparation of the polymer-viscosity-reducing oil displacement agent mixed solution: weighing 0.15g of viscosity-reducing oil-displacing agent sample (accurate to 0.001g) in a 150mL beaker, adding 29.85g of saline, stirring for 15min at the rotating speed of 300r/min on a magnetic stirrer, then adding 20.0g of polymer mother liquor, and stirring for 30min at the rotating speed of 300r/min on the magnetic stirrer to obtain the polymer-viscosity-reducing oil-displacing agent mixed solution.
3.4 weighing 30.0g of the polymer-viscosity reduction oil displacement agent mixed solution prepared by 3.3, putting the mixed solution into a 250mL beaker, adding 70.0g of experimental oil sample, sealing, putting the beaker into a constant-temperature drying oven, and keeping the temperature for 2 hours at the oil reservoir temperature. The viscosity of the oil-water mixed solution at the reservoir temperature was measured as in 1.3, and the viscosity reduction rate was calculated as in formula (1).
3.5 according to SY/T5370-2018 in 7.5, the interfacial tension between the polymer-viscosity-reducing oil displacement agent mixed solution and the experimental oil sample is measured at the oil reservoir temperature.
3.6 the apparent viscosities of the single polymer solution and the polymer-viscosity reducing oil-displacing agent mixed solution were measured at the reservoir temperature as defined in SY/T5862-2020, 6.5.1.4.
3.7 viscosity Retention is calculated as in equation (3):
in the formula: n-viscosity retention, expressed in percent;
η1the apparent viscosity of the single polymer solution in millipascal seconds (mPa · s);
η2the apparent viscosity of the polymer-viscosity reducing oil displacement agent mixed solution is expressed in millipascal seconds (mPa & s).
4. Thermal stability test
4.1 preparing 200.0g of 0.3% viscosity-reducing oil-displacing agent solution, respectively filling about 30mL of sample solution into 5 ampoules each time, vacuumizing the ampoules, introducing nitrogen to remove oxygen according to the specification of 6.13 in SY/T5862-2020, and then placing the sealed ampoules in a constant-temperature drying oven for storage at the oil reservoir temperature.
4.2 after the aging time reaches 1, 3, 7, 15 and 30 days, respectively taking out 1 ampoule bottle, putting 15.0g of the aged sample solution into a 150mL beaker, adding 35.0g of an experimental oil sample, sealing, placing in a constant-temperature drying oven, and keeping the temperature at the oil reservoir temperature for 2 hours.
4.3 the viscosity of the oil-water mixture at the reservoir temperature is measured as 1.3 and the viscosity reduction rate after thermal ageing is calculated as formula (1).
5. Oil wash test
5.1 mixing the simulated formation sand with the experimental oil sample according to a mass ratio of 4:1, putting the mixture into a constant-temperature drying box, aging the mixture for 7 days at the oil reservoir temperature, stirring the mixture for 1 time every day to uniformly mix the oil sand, and taking the mixture out for later use.
5.2 weigh 5g of aged oil sand (mass m, to the nearest 0.001g) into a 100mL Erlenmeyer flask (Erlenmeyer flask mass m)1And the concentration is accurate to 0.001g), 50.0g of viscosity-reducing oil displacement agent solution with the concentration of 0.3 percent is added, and the mixture is fully mixed and then stands for 48 hours at the oil reservoir temperature.
5.3 dip out the crude oil that floats in the sample solution after will standing and the crude oil of adhesion on the bottle wall with clean cotton yarn, pour out sample solution, wash oil sand 2 ~ 3 times with distilled water and do not have the foam, pour out solution carefully. Placing the conical flask in a 105 ℃ constant temperature drying oven to constant weight, weighing (recording as m)2To the nearest 0.001 g).
5.4 using petroleum ether to elute crude oil from the dried oil sand in 7.6.3 until the petroleum ether is colorless, placing the conical flask after eluting the crude oil in an oven at 120 ℃ for drying for 2h, and weighing (marking as m)3To the nearest 0.001 g).
5.5 the oil wash rate was calculated according to equation (2):
in the formula: σ -oil wash rate, expressed as a percentage;
m is the mass of the aged oil sand in grams (g);
m1-the mass of the erlenmeyer flask in grams (g);
m2the total mass of the erlenmeyer flask and the oil sand after washing the oil, in grams (g);
m3the total mass of the flask and the washed formation sand in grams (g).
The viscosity reduction oil displacement agent for ordinary heavy oil reservoir viscosity reduction composite flooding obtained in the above examples 1 to 6 and comparative examples 1 to 9 was subjected to the tests of adsorption resistance, natural sedimentation dehydration rate, compatibility with a polymer, thermal stability, and oil wash rate according to the above test methods, and the test results are shown in tables 1, 2, and 3. Wherein, the standard requirements of each parameter in the technical requirements of viscosity-reducing oil displacement agent for the compound flooding of common heavy oil reservoirs are as follows:
anti-adsorption property: the viscosity reduction rate after adsorption is more than or equal to 80.0 percent, and the interfacial tension after adsorption is less than or equal to 9.9 multiplied by 10-2mN/m；
And (3) natural settling dehydration rate: more than or equal to 80.0 percent;
compatibility with Polymer: viscosity reduction rate is more than or equal to 80.0 percent, and interfacial tension is less than or equal to 9.9 multiplied by 10-2mN/m; the viscosity retention rate is more than or equal to 95.0 percent;
thermal stability: the viscosity reduction rate is more than or equal to 80.0 percent in 30 days under the anaerobic condition; oil washing rate: not less than 40.0 percent.
Table 1 viscosity reduction oil displacement agent for viscosity reduction composite flooding adsorptivity resistance and natural settling dehydration rate test
Table 2 thermal stability and wash rate testing of viscosity-reducing oil displacement agent for viscosity-reducing composite flooding
TABLE 3 compatibility test of viscosity-reducing oil-displacing agent for viscosity-reducing composite flooding and polymer
Sample name
Viscosity reduction ratio after addition of polymer%
Interfacial tension after addition of Polymer, mN/m
Viscosity retention rate,%
Example 1
88.5
3.3×10-2
101.2
Example 2
87.6
2.6×10-2
102.5
Example 3
86.9
3.5×10-2
102.1
Example 4
89.1
3.6×10-2
101.4
Example 5
87.5
2.0×10-2
102.9
Example 6
88.4
2.3×10-2
100.8
Comparative example 1
63.2
0.11
98.2
Comparative example 2
56.0
0.10
97.3
Comparative example 3
63.4
0.11
94.7
Comparative example 4
62.6
0.11
96.0
Comparative example 5
53.5
0.13
94.3
Comparative example 6
50.3
0.11
95.1
Comparative example 7
51.9
0.13
96.3
Comparative example 8
51.3
0.12
94.5
Comparative example 9
55.3
0.10
96.4
As can be seen from the data in tables 1 to 3, the formula provided by the invention can enable the obtained viscosity reduction oil displacement agent for the viscosity reduction compound flooding of the common heavy oil reservoir to have the characteristics of strong adsorption resistance, good thermal stability, high oil washing rate, good compatibility with polymers and the like under the synergistic effect of the nano viscosity reducer, the isopropanolamide, the imidazoline and the component ratios thereof, and when the formula is applied to the viscosity reduction compound flooding of the common heavy oil reservoir, the oil washing capacity can be enhanced, the flowability of crude oil can be increased, the sweep can be enlarged, and the recovery ratio of the common heavy oil reservoir can be greatly increased. It is worth to be noted that the determination of the technical indexes of the viscosity reduction oil displacement agent for viscosity reduction composite flooding is determined by the successful experience of binary flooding (polymer + surfactant), and the practical application verifies that the indexes are all not enough, and if one index is not met, the expected effect of the application cannot be achieved.