Temperature-resistant and salt-resistant common heavy oil viscosity-reducing flooding agent and its preparation method and application

Abstract

The present invention provides a heat-resistant and salt-resistant common heavy oil viscosity-reducing and oil-displacing agent, and a preparation method and application thereof, which belongs to the field of oilfield chemical technology and can solve the technical problem that the existing heavy oil viscosity-reducing agents cannot effectively meet the requirements of heat resistance and salt resistance in heavy oil cold production. The heat-resistant and salt-resistant common heavy oil viscosity-reducing and oil-displacing agent provided by the present invention comprises, by mass percentage, 20% to 25% of a nonionic surfactant, 25% to 30% of an anionic surfactant, 15% to 20% of a high-temperature resistant emulsified viscosity-reducing agent, 5% of an auxiliary agent, and the rest is water. The heat-resistant and salt-resistant heavy oil viscosity-reducing agent can be effectively applied to heavy oil reservoirs with a temperature of ≤90°C, a formation water mineralization of ≥100,000 mg / L, and calcium and magnesium ions of ≥5500 mg / L, and its viscosity reduction rate is ≥95%, the oil washing rate is ≥45%, and the interfacial tension is ≤8.2×10 ‑2 , which can effectively improve the viscosity reduction rate of heavy oil in high-temperature salt reservoirs and increase the recovery rate of heavy oil.

Description

Technical Field

[0001] The invention belongs to the technical field of oilfield chemistry, and in particular relates to a temperature-resistant and salt-resistant common heavy oil viscosity-reducing and oil-displacing agent, and a preparation method and application thereof. Background Art

[0002] With the deepening of water injection development, the production of most heavy oil reservoirs has gradually declined due to factors such as the intensification of injection-production contradictions, the decline of formation energy, and reservoir blockage, and the easy-to-extract heavy oil blocks have continued to decrease. Efficient heavy oil extraction has been the focus of research in recent years. The main technologies for heavy oil extraction are thermal extraction and cold extraction. Among them, the heavy oil cold extraction technology for improving oil recovery has received more and more attention, and the chemical viscosity reducer method in heavy oil cold extraction is a relatively new technology.

[0003] Currently available heavy oil viscosity reducer technologies are generally resistant to temperature differences, easily hydrolyzed, and difficult to form stable emulsions at high salinity. They are also difficult to expand the swept volume and improve oil recovery efficiency in high-temperature and high-salinity oil layers, and cannot meet the requirements for heavy oil production in high-temperature and high-salinity reservoirs. Summary of the invention

[0004] The present invention provides a temperature-resistant and salt-resistant common heavy oil viscosity-reducing oil-displacing agent, and a preparation method and application thereof. The temperature-resistant and salt-resistant heavy oil viscosity-reducing oil-displacing agent has good solubility, excellent temperature resistance and salt resistance, strong solution stability, is not easy to hydrolyze for a long time, can effectively change the wettability of the formation at high temperature, increase the oil-water swept volume, and improve the oil displacement efficiency.

[0005] In order to achieve the above-mentioned purpose, the present invention provides a temperature-resistant and salt-resistant common heavy oil viscosity reducing oil displacement agent, which comprises, by mass percentage, 20% to 25% of a nonionic surfactant, 25% to 30% of anionic surfactant, 15% to 20% of a high-temperature resistant emulsified viscosity reducing agent, 5% of an auxiliary agent, and the rest is water.

[0006] Preferably, the high temperature resistant emulsified viscosity reducer AESO has the following structural formula:

[0007] CH3CH2CH2-CH2CH2(OCH2CH2)n-SO3Na, wherein n is an integer of 3-5.

[0008] Preferably, the high temperature resistant emulsified viscosity reducer AESO is obtained by the following synthesis method:

[0009] Weigh n(fatty alcohol polyoxyethylene ether AEO) and n(sodium 2-bromoethyl sulfonate) in a molar ratio of 1:1.3 respectively, first place AEO in a reaction container, heat until it is completely melted, add an appropriate amount of sodium hydroxide, stir for 25-35 minutes, and add sodium 2-bromoethyl sulfonate while stirring;

[0010] After the reaction is completed, a brown paste is produced. The brown paste is dissolved in anhydrous ethanol to remove unreacted sodium 2-bromoethylsulfonate. The anhydrous ethanol is evaporated at 80° C. and finally recrystallized from anhydrous ethanol and dried in vacuo to obtain an AESO solid product.

[0011] The synthesis principle of the high temperature resistant emulsified viscosity reducer AESO used is as follows:

[0012]

[0013] R(OCH2CH2)nONa+BrCH2CH2SO3Na→R(OCH2CH2)SO3Na+NaBr

[0014] Preferably, the anionic surfactant sodium N-acyl sarcosinate has the general molecular formula:

[0015]

[0016] Wherein, R is a C8-C14 high carbon alkyl group.

[0017] Preferably, the nonionic surfactant is lauric acid diethanolamide.

[0018] Preferably, the auxiliary agent is ethanol.

[0019] The present invention also provides a method for preparing the temperature-resistant and salt-resistant common heavy oil viscosity-reducing flooding agent according to any one of the above technical solutions, comprising the following steps:

[0020] Add the high temperature resistant viscosity reducing emulsifier AESO into the reaction kettle, then add ethanol, stir evenly at 30°C-40°C, add sodium N-acyl sarcosinate, lauric acid diethanolamide and water in sequence, stir for 30-40 minutes, and obtain a heat resistant and salt resistant common heavy oil viscosity reducing flooding agent.

[0021] The present invention also provides an application of the temperature-resistant and salt-resistant common heavy oil viscosity-reducing oil-displacing agent according to any of the above technical solutions in the exploitation of heavy oil reservoirs with a temperature of ≤90°C, a formation water salinity of ≥100,000 mg / L, and a calcium and magnesium ion content of ≥5,500 mg / L.

[0022] Preferably, the temperature-resistant and salt-resistant common heavy oil viscosity-reducing flooding agent is used in a 0.3% aqueous solution.

[0023] As a preferred embodiment, when the temperature-resistant and salt-resistant common heavy oil viscosity-reducing oil-displacing agent is used in a heavy oil reservoir with a temperature of ≤90°C, a formation water salinity of ≥100,000 mg / L, and calcium and magnesium ions of ≥5,500 mg / L, the viscosity reduction rate is ≥95%, the oil washing rate is ≥45%, and the interfacial tension is ≤8.2×10 -2 .

[0024] Compared with the prior art, the advantages and positive effects of the present invention are:

[0025] 1. The heat-resistant and salt-resistant heavy oil viscosity-reducing flooding agent has good solubility, excellent heat-resistant and salt-resistant performance, strong solution stability, and is not easy to hydrolyze for a long time in the formation.

[0026] 2. This heat-resistant and salt-resistant heavy oil viscosity-reducing flooding agent can effectively change the wettability of the formation at high temperature, increase the oil-water swept volume, and improve the oil recovery efficiency.

[0027] 3. The production process of the temperature-resistant and salt-resistant heavy oil viscosity-reducing flooding agent is simple, the raw materials are easily purchased and do not contain organic chlorine, which meets the requirements of green environmental protection. DETAILED DESCRIPTION

[0028] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] Example 1

[0030] 150 kg of heat-resistant emulsified viscosity reducer AESO was added into the reactor, and then 50 kg of ethanol was added, and stirred evenly at 30-40 ° C. 300 kg of anionic surfactant sodium N-acyl sarcosinate, 250 kg of nonionic surfactant lauric acid diethanolamide and 250 kg of water were added in sequence, and stirred for 30-40 minutes to obtain a heat-resistant and salt-resistant ordinary heavy oil viscosity reducer.

[0031] Example 2

[0032] 160 kg of heat-resistant emulsified viscosity reducer AESO was added into the reactor, and then 50 kg of ethanol was added, and stirred evenly at 30-40°C. 290 kg of anionic surfactant sodium N-acyl sarcosinate, 240 kg of nonionic surfactant lauric acid diethanolamide and 260 kg of water were added in sequence, and stirred for 30-40 minutes to obtain a heat-resistant and salt-resistant ordinary heavy oil viscosity reducer displacement agent.

[0033] Example 3

[0034] 170 kg of heat-resistant emulsified viscosity reducer AESO was added into the reactor, and then 50 kg of ethanol was added, and stirred evenly at 30-40°C. 280 kg of anionic surfactant sodium N-acyl sarcosinate, 230 kg of nonionic surfactant lauric acid diethanolamide and 270 kg of water were added in sequence, and stirred for 30-40 minutes to obtain a heat-resistant and salt-resistant ordinary heavy oil viscosity reducer.

[0035] Example 4

[0036] 180 kg of heat-resistant emulsified viscosity reducer AESO was added into the reactor, and then 50 kg of ethanol was added, and stirred evenly at 30-40 ° C. 270 kg of anionic surfactant sodium N-acyl sarcosinate, 220 kg of nonionic surfactant lauric acid diethanolamide and 280 kg of water were added in sequence, and stirred for 30-40 minutes to obtain a heat-resistant and salt-resistant ordinary heavy oil viscosity reducer.

[0037] Example 5

[0038] 190 kg of heat-resistant emulsified viscosity reducer AESO was added into the reactor, and then 50 kg of ethanol was added, and stirred evenly at 30-40°C. 260 kg of anionic surfactant sodium N-acyl sarcosinate, 210 kg of nonionic surfactant lauric acid diethanolamide and 290 kg of water were added in sequence, and stirred for 30-40 minutes to obtain a heat-resistant and salt-resistant ordinary heavy oil viscosity reducer.

[0039] Example 6

[0040] 200 kg of heat-resistant emulsified viscosity reducer AESO was added into the reactor, and then 50 kg of ethanol was added, and stirred evenly at 30-40°C. 250 kg of anionic surfactant sodium N-acyl sarcosinate, 200 kg of nonionic surfactant lauric acid diethanolamide and 300 kg of water were added in sequence, and stirred for 30-40 minutes to obtain a heat-resistant and salt-resistant ordinary heavy oil viscosity reducer.

[0041] Comparative Example 1

[0042] 50 kg of ethanol, 300 kg of anionic surfactant sodium N-acyl sarcosinate, 250 kg of nonionic surfactant lauric acid diethanolamide and 400 kg of water were added to the reactor, and after stirring for 30-40 minutes, a temperature-resistant and salt-resistant ordinary heavy oil viscosity-reducing flooding agent was obtained.

[0043] Comparative Example 1 is a heat-resistant and salt-resistant common heavy oil viscosity reducing flooding agent obtained by removing the high-temperature resistant emulsified viscosity reducing agent AESO in the formula of Example 1, wherein the amount of the high-temperature resistant emulsified viscosity reducing agent is made up by water.

[0044] Comparative Example 2

[0045] 150 kg of heat-resistant emulsified viscosity reducer AESO was added into the reactor, and then 50 kg of ethanol was added, and stirred evenly at 30-40°C. 250 kg of nonionic surfactant lauric acid diethanolamide and 550 kg of water were added, and stirred for 30-40 minutes to obtain a heat-resistant and salt-resistant ordinary heavy oil viscosity reducer.

[0046] Comparative Example 2 is a temperature-resistant and salt-resistant common heavy oil viscosity-reducing flooding agent obtained by removing the anionic surfactant sodium N-acyl sarcosinate in the formula of Example 1, wherein the amount of the anionic surfactant sodium N-acyl sarcosinate is made up by water.

[0047] Comparative Example 3

[0048] 150 kg of heat-resistant emulsified viscosity reducer AESO was added into the reactor, and then 50 kg of ethanol was added, and stirred evenly at 30-40°C. 300 kg of anionic surfactant sodium N-acyl sarcosinate and 500 kg of water were added, and stirred for 30-40 minutes to obtain a heat-resistant and salt-resistant common heavy oil viscosity reducer.

[0049] Comparative Example 3 is a temperature-resistant and salt-resistant common heavy oil viscosity-reducing flooding agent obtained by removing the nonionic surfactant lauric acid diethanolamide from the formula of Example 1, wherein the amount of the nonionic surfactant lauric acid diethanolamide is made up by water.

[0050] Comparative Example 4

[0051] 140 kg of high temperature resistant emulsified viscosity reducer AESO was added into the reactor, and then 50 kg of ethanol was added, and stirred evenly at 30-40 °C. 300 kg of anionic surfactant sodium N-acyl sarcosinate, 250 kg of nonionic surfactant lauric acid diethanolamide and 260 kg of water were added in sequence, and stirred for 30-40 minutes to obtain a heat-resistant and salt-resistant ordinary heavy oil viscosity reducer displacement agent.

[0052] Comparative Example 4 is a heat-resistant and salt-resistant common heavy oil viscosity-reducing flooding agent obtained by adjusting the amount of the high-temperature-resistant emulsified viscosity-reducing agent AESO in the formula of Example 1 to 140 kg (the content is reduced to 14%), and the reduced amount is made up by water.

[0053] Comparative Example 5

[0054] 150 kg of heat-resistant emulsified viscosity reducer AESO was added into the reactor, and then 50 kg of ethanol was added, and stirred evenly at 30-40 °C. 300 kg of anionic surfactant sodium N-acyl sarcosinate, 190 kg of nonionic surfactant lauric acid diethanolamide and 310 kg of water were added in sequence, and stirred for 30-40 minutes to obtain a heat-resistant and salt-resistant ordinary heavy oil viscosity reducer displacement agent.

[0055] Comparative Example 5 is a high temperature resistant emulsified viscosity reducer obtained by adjusting the amount of the nonionic surfactant lauric acid diethanolamide in the formula of Example 1 to 190 kg (the content is reduced to 19%), and the reduced amount is made up by water.

[0056] Comparative Example 6

[0057] 150 kg of heat-resistant emulsified viscosity reducer AESO was added into the reactor, and then 50 kg of ethanol was added, and stirred evenly at 30-40 ° C. 240 kg of anionic surfactant sodium N-acyl sarcosinate, 250 kg of nonionic surfactant lauric acid diethanolamide and 310 kg of water were added in sequence, and stirred for 30-40 minutes to obtain a heat-resistant and salt-resistant ordinary heavy oil viscosity reducer.

[0058] Comparative Example 6 is the anionic surfactant sodium N-acyl sarcosinate in the formula of Example 1 adjusted to 240 kg (content reduced to 24%), and the reduced amount is made up by water.

[0059] Performance Testing

[0060] 1. Test instruments: DV-3T rheometer, constant temperature drying oven, TX-500C full-range rotating drop interfacial tension meter

[0061] 2. Experimental temperature: 90℃

[0062] 3. Experimental oil and water: dehydrated crude oil from a block of Shengli Oilfield (viscosity 3250mPa.s at reservoir temperature), injected water: 100000mg / L, calcium and magnesium ion content: 5500mg / L

[0063] 4. The above-configured temperature-resistant and salt-resistant common heavy oil viscosity-reducing and oil-displacing agent was prepared into an aqueous solution with a concentration of 0.3% using injection water from a block of Shengli Oilfield.

[0064] Interfacial tension test:

[0065] The interfacial tension between the oil displacement agent sample solution and the experimental oil sample was measured at 90°C, and the lowest interfacial tension value was recorded.

[0066] Viscosity reduction test:

[0067] Place the experimental oil sample in a constant temperature drying oven and keep it at the reservoir temperature for 1 hour. Set the measurement temperature of the rotational viscometer to 90°C, pour the experimental oil sample into the measuring cylinder of the rotational viscometer, and set the shear rate to 60s -1 , according to the provisions of 4.4 of SY / T0520-2008, test the viscosity of the experimental oil sample at reservoir temperature.

[0068] Prepare 100g of a heat-resistant and salt-resistant common heavy oil viscosity-reducing and flooding agent with a concentration of 3%, weigh 20g of the sample solution and put it into a 250mL beaker, then add 80g of the experimental oil sample, so that the mass ratio of the experimental oil sample to the sample solution is 8:2. After sealing, place it in a constant temperature drying oven and keep it at a constant temperature for 2h at the reservoir temperature. Take out the sample, stir the oil-water mixture continuously with a glass rod at a rate of 100 times / min for 3min to mix the oil and water evenly, and quickly pour it into the measuring cylinder of the rotary viscometer, set the shear rate to 60s-1, and measure the viscosity of the oil-water mixture at 90℃.

[0069] Oil washing rate test:

[0070] Mix the simulated formation sand and the experimental oil sample in a ratio of 4:1 (mass ratio), put them in a constant temperature drying oven, age them at 90°C for 7 days, stir them once a day to mix the oil sands evenly, and take them out for use. Weigh 5g of aged oil sands (mass is m, accurate to 0.001g) and put them in a conical flask (the mass of the conical flask is m1, accurate to 0.001g), add 50g of 0.3% oil displacement agent sample solution, mix them thoroughly and let them stand at 90°C for 48h. Dip out the crude oil floating in the sample solution and the crude oil adhering to the bottle wall with clean cotton yarn after standing, pour out the sample solution, rinse the oil sands with distilled water until there is no foam, and carefully pour out the solution. Place the conical flask in a constant temperature drying oven at 105°C and dry it to constant weight, and weigh it (recorded as m2, accurate to 0.001g). Use petroleum ether to elute the crude oil from the dried oil sands until the petroleum ether is colorless. Place the conical flask with the crude oil removed in a 120℃ oven for 2 hours and dry it. Weigh it (recorded as m3, accurate to 0.001g). Use petroleum ether to elute the crude oil from the dried oil sands until the petroleum ether is colorless. Place the conical flask with the crude oil removed in a 120℃ oven for 2 hours and dry it. Weigh it (recorded as m3, accurate to 0.001g).

[0071] The oil washing rate is calculated as follows:

[0072] δ=(m+m1-m2) / (m+m1-m3)×100%

[0073] δ-oil washing rate, expressed as a percentage;

[0074] m-mass of aged oil sands, in grams;

[0075] m1-the mass of the conical flask, in grams;

[0076] m2-the total mass of the conical flask and oil sand after oil washing, in grams;

[0077] m3-the total mass of the conical flask and the washed formation sand, in grams;

[0078] The temperature-resistant and salt-resistant common heavy oil viscosity-reducing and oil-displacing agents prepared in the above Examples 1-6 and Comparative Examples 1-6 were tested for interfacial tension, viscosity reduction rate, and oil washing rate according to the above test methods. The test results are shown in Table 1. Among them, the standards for the following parameters are: interfacial tension ≤9.9×10 -2 , viscosity reduction rate ≥95%, oil washing rate ≥40%.

[0079] Table 1: Performance test of heat-resistant and salt-resistant common heavy oil viscosity-reducing flooding agent

[0080]

[0081]

[0082] As can be seen from Table 1, the formula provided by the present invention can make the obtained heat-resistant and salt-resistant common heavy oil viscosity-reducing flooding agent meet the interfacial tension of ≤9.9×10 -2 , viscosity reduction rate ≥95%, oil washing rate ≥40%, and the performance is more advantageous than it, the interfacial tension reaches ≤8.2×10 -2 This is because AESO can significantly improve the viscosity reduction rate under high temperature and high salinity conditions, sodium N-acyl sarcosinate can increase the oil-water swept volume and improve the oil recovery efficiency, and lauric acid diethanolamide can effectively reduce the interfacial tension. The three can synergistically change the formation wettability, increase the oil-water swept volume, and improve the oil recovery efficiency. If a certain component is missing or the amount of the component used is not within the scope specified by the present invention, it will affect the tested indicators and cause them to fail.

Claims

1. A heat-resistant and salt-resistant common heavy oil viscosity-reducing flooding agent, characterized in that: In terms of mass percentage, it includes 20% to 30% non-ionic surfactant, 15% to 25% anionic surfactant, 10% to 20% high temperature resistant emulsifying viscosity reducer, 5% to 10% auxiliary agent, and the rest is water; The high temperature resistant emulsified viscosity reducer AESO has the following structural formula: CH3CH2CH2-CH2CH2(OCH2CH2)n-SO3Na, wherein n is an integer from 3 to 5; The anionic surfactant is sodium N-acyl sarcosinate, and its molecular formula is as follows: Wherein, R is a C8-C14 high carbon alkyl group; The nonionic surfactant is lauric acid diethanolamide.

2. The heat-resistant and salt-resistant common heavy oil viscosity-reducing flooding agent according to claim 1, characterized in that: The auxiliary agent is ethanol.

3. The method for preparing the temperature-resistant and salt-resistant common heavy oil viscosity-reducing flooding agent according to claim 1 or 2, characterized in that: The following steps are involved: Add the high temperature resistant viscosity reducing emulsifier AESO into the reactor, then add ethanol, stir evenly at 30℃~40℃, add sodium N-acyl sarcosinate, lauric acid diethanolamide and water in sequence, stir for 30-40min, and obtain the temperature resistant and salt resistant common heavy oil viscosity reducing flooding agent.

4. Use of the temperature-resistant and salt-resistant common heavy oil viscosity-reducing oil-displacing agent according to claim 1 or 2 in the exploitation of heavy oil reservoirs with a temperature of ≤90°C, a formation water salinity of ≥100,000 mg / L, and a calcium and magnesium ion content of ≥5,500 mg / L.

5. The use according to claim 4, characterized in that: The use concentration of the heat-resistant and salt-resistant common heavy oil viscosity-reducing flooding agent is 0.3% aqueous solution.

6. The use according to claim 5, characterized in that: When the temperature-resistant and salt-resistant common heavy oil viscosity-reducing and oil-displacing agent is used in a heavy oil reservoir with a temperature of ≤90°C, a formation water salinity of ≥100,000 mg / L, and a calcium and magnesium ion of ≥5,500 mg / L, the viscosity reduction rate is ≥95%, the oil washing rate is ≥45%, and the interfacial tension is ≤8.2×10 -2 .

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