CN114058354B - Foam oil displacement agent suitable for high-salinity low-permeability reservoir and preparation method and application thereof - Google Patents
Foam oil displacement agent suitable for high-salinity low-permeability reservoir and preparation method and application thereof Download PDFInfo
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- CN114058354B CN114058354B CN202111476384.0A CN202111476384A CN114058354B CN 114058354 B CN114058354 B CN 114058354B CN 202111476384 A CN202111476384 A CN 202111476384A CN 114058354 B CN114058354 B CN 114058354B
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- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- C09K8/00—Compositions for drilling of boreholes or wells; Compositions for treating boreholes or wells, e.g. for completion or for remedial operations
- C09K8/58—Compositions for enhanced recovery methods for obtaining hydrocarbons, i.e. for improving the mobility of the oil, e.g. displacing fluids
- C09K8/584—Compositions for enhanced recovery methods for obtaining hydrocarbons, i.e. for improving the mobility of the oil, e.g. displacing fluids characterised by the use of specific surfactants
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- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- C09K8/00—Compositions for drilling of boreholes or wells; Compositions for treating boreholes or wells, e.g. for completion or for remedial operations
- C09K8/58—Compositions for enhanced recovery methods for obtaining hydrocarbons, i.e. for improving the mobility of the oil, e.g. displacing fluids
- C09K8/594—Compositions used in combination with injected gas, e.g. CO2 orcarbonated gas
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- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B43/00—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
- E21B43/16—Enhanced recovery methods for obtaining hydrocarbons
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- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B43/00—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
- E21B43/16—Enhanced recovery methods for obtaining hydrocarbons
- E21B43/164—Injecting CO2 or carbonated water
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- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B43/00—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
- E21B43/16—Enhanced recovery methods for obtaining hydrocarbons
- E21B43/166—Injecting a gaseous medium; Injecting a gaseous medium and a liquid medium
- E21B43/168—Injecting a gaseous medium
Abstract
The invention provides a foam oil displacement agent suitable for a high-salinity low-permeability oil reservoir, which comprises the following components in percentage by weight: tris [ (N-dodecyl-N-ethyl-N-carboxymethyl sodium) -2-ammoniumbromide ethylene radical]Amine: 0.4-0.6%, dodecyl dimethyl amine oxide: 0.1-0.35%, sodium salicylate: 0.02-0.07%, chelating agent: 0.04-0.14%, inorganic salt: 6-10% and the balance of water. The invention also provides a preparation method and application of the ultralow interfacial tension self-assembly carbon dioxide foam oil displacement agent. The self-assembled carbon dioxide foam oil displacement agent has good salt resistance, acid and alkali resistance, higher viscosity of foaming liquid, and improved foam interface film strength and stability, and can make oil-water interface tension reach 10 ‑3 The magnitude order of mN/m is less than or equal to mN/m, the foam generated by the experiment is fine and rich, the injection property in the low-permeability reservoir is good, the oil-water fluidity ratio can be improved, the sweep efficiency is obviously enlarged, and the oil washing efficiency is improved; the foaming agent does not produce salting-out phenomenon to lose interfacial activity, and does not produce chemical reaction with calcium and magnesium ions to generate precipitate to lose interfacial activity.
Description
Technical Field
The invention belongs to the field of chemical oil displacement, and particularly relates to a foam oil displacement agent suitable for a high-salinity low-permeability reservoir, and a preparation method and application thereof.
Background
The gas drive is selected for the low-permeability oil reservoir because the migration capacity of gas in the low-permeability oil reservoir is weakened, the gas channeling time is greatly delayed, the volume of the accessible pore in the low-permeability oil reservoir and even a compact oil reservoir is increased, the gas injection of the low-permeability oil reservoir in an oil field is prolonged, such as the injection of carbon dioxide, and a certain effect is achieved.
The low-permeability reservoir is prolonged to have the characteristics of low porosity, low permeability and low yield, the development effect of the low-permeability reservoir can be improved by adopting the conventional water injection and gas injection method, but the low-permeability reservoir is low in exploitation degree and recovery ratio due to the fact that 'no injection', or water channeling and gas channeling are easy to occur in the middle and later stages of development and the injection fluid wave and efficiency are low. The currently common methods are: polymer flooding, surfactant flooding, alkali water flooding and foam flooding. The alkali water flooding can reduce the viscoelasticity of the system and increase the treatment difficulty of the produced liquid; polymer flooding is not suitable for low permeability fields with small injection gaps, which are difficult to inject.
The foam flooding can improve the recovery ratio of the low-permeability reservoir by improving the fluidity ratio, reducing the tension of an oil-water interface, improving the oil washing efficiency, increasing the formation energy, reducing the starting pressure and the water injection pressure and improving the seepage capability of the mixed fluid. The main reason that the foam has the functions of profile control and oil displacement is the seepage characteristic of the foam in a porous medium, namely the characteristics of large foam plugging, small foam plugging and water plugging and oil plugging, so that the foam is uniformly propelled at high and low permeability; at the same time, the foam also has a certain effect of reducing the interfacial tension. Therefore, the foam can improve the recovery rate remarkably, the foam flooding can improve the recovery rate by more than 25% in general conditions, and the polymer flooding can improve the recovery rate by 10-20%. For the prolonged low-permeability reservoir with low-permeability low-pore and low-pressure characteristics, most pore throats belong to slender pore throats, the pore diameter is too small, and polymer flooding is not injected because the molecular weight is large and the hydraulic radius of random coils is large, and the water flooding effect is not good, so that foam flooding is considered.
The fluidity control capability of the foam system is stronger than that of a polymer, the flow front edge is more stable, the volume sweep coefficient is higher, the foam oil washing capability is stronger, the dosage of a surfactant can be saved, and meanwhile, the foam oil washing agent has better foam performance and ultralow interfacial tension, reduces ineffective water circulation, does not contain strong alkali or weak alkali, avoids corrosion and scaling, and improves economic benefits.
Currently, although some foam oil-displacing agents have been developed in the market, there still exist problems such as poor foamability of foam in saline, low viscosity, insufficient reduction of interfacial tension, low foam combination index, unstable foam, and the like. For example, patent ZL201710864250.3 of the invention relates to a self-assembly ultramicro foam oil displacement agent and a preparation method and application thereof, and the invention has the practical problems of low interfacial tension under the condition of high salinity, low foaming liquid viscosity, insufficient foam strength, relatively high cost, good reservoir permeability and strong low-permeability reservoir expansion fluctuation and insufficient volume. In addition, while some foaming systems have reduced interfacial tension and high strength, the surfactant concentrations used are too high, resulting in a cost that is too high to be used in the field at all. For example, in the invention patent CN110776893A, "an ultra-low interfacial tension strong foam oil displacement agent", the minimum concentration of the used surfactant reaches 30%, while the oil displacement efficiency is 16-21%, and the oil displacement efficiency is not high, so that the method is difficult to be applied to oil fields in a large scale. Aiming at the actual problems and the characteristics of the low-permeability reservoir, through molecular structure design and repeated experiments, under the same experimental conditions as patent ZL201710864250.3, the ultralow interfacial tension self-assembly oil displacement agent suitable for the low-permeability reservoir, disclosed by the invention, has the advantages that the oil-water interfacial tension is reduced to be lower, the ultralow value or even lower is achieved, the viscosity of the composite vermiform micelle formed by self-assembly under the same dosage condition is higher, the formed foam has longer stable time, and the sweep expansion efficiency is more remarkable.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides a foam oil displacement agent suitable for a high-salinity low-permeability reservoir and application thereof, wherein each component of the foam can be self-assembled to form a composite worm-shaped micelle, so that the viscosity of the system is increased, the foam oil displacement agent has the characteristics of no alkali and no corrosion, has the salt and acid resistance capability, can ensure that the oil-water interfacial tension is ultralow, and the generated foam is fine, stable and rich.
A foam oil displacement agent suitable for a high-salinity low-permeability oil reservoir comprises the following components in percentage by weight:
tris [ (N-dodecyl-N-ethyl-N-carboxymethyl sodium) -2-ammonium ethylene bromide ] amine: 0.4 to 0.6 percent of,
nonionic surfactant dodecyl dimethyl amine oxide: 0.1 to 0.35 percent of,
counter-ionic compound sodium salicylate: 0.02 to 0.07 percent of the total weight of the mixture,
chelating agent: 0.04-0.14 percent of,
inorganic salts: 5-7% of the total weight of the mixture,
the balance of water,
wherein the structural formula of the tri [ (N-dodecyl-N-ethyl-N-carboxymethyl sodium) -2-ammonium ethylene bromide ] amine is shown in the specification
The tri [ (N-dodecyl-N-ethyl-N-carboxymethyl sodium) -2-ammonium ethylene bromide ] amine is a trimeric betaine surfactant.
The tris [ (N-dodecyl-N-ethyl-N-carboxymethyl sodium) -2-ammonium ethylene bromide ] amine is a surfactant in the prior art, and the preparation method is shown in a paper of synthesis and performance evaluation of tris [ (N-dodecyl-N-ethyl-N-carboxymethyl sodium) -2-ammonium ethylene bromide ] amine, a chemical reagent and 2016, published by Zhou Ming subject group of southwestern university of Petroleum.
Preferably, the nonionic surfactant is dodecyl dimethyl amine oxide (0B-2).
Preferably, the counter-ionic compound is sodium salicylate.
Preferably, the chelating agent is EDTA.
Preferably, the inorganic salt is any one or more of sodium chloride, magnesium chloride, sodium sulfate, sodium bisulfate, sodium carbonate, potassium chloride and calcium chloride. When the inorganic salt is any of sodium chloride, magnesium chloride, sodium sulfate, sodium bisulfate, sodium carbonate, potassium chloride and calcium chloride, the components of any of the components are mixed in any proportion.
The preparation method of the ultralow interfacial tension self-assembly carbon dioxide foam oil displacement agent suitable for the low-permeability oil reservoir comprises the following steps:
(1) Heating water to 70 ℃, adding inorganic salt, adding tris [ (N-dodecyl-N-ethyl-N-carboxymethyl sodium) -2-ammonium bromide ethylene group ] amine, and stirring for dissolving;
(2) And (2) sequentially adding a nonionic surfactant dodecyl dimethyl amine oxide and a chelating agent into the mixed solution obtained in the step (1), and stirring for dissolving.
(3) And (3) adding sodium salicylate into the mixed solution obtained in the step (2), and stirring for dissolving.
And (4) measuring the viscosity of the high-salinity low-permeability reservoir foam oil displacement agent by using a Brookfield VIII viscometer for the mixed solution obtained in the step (3), and measuring the interfacial tension by using a Tax500 ultralow-rotation interfacial tension meter.
The foam oil displacement agent suitable for the high-salinity low-permeability oil reservoir and the application thereof are as follows: adding a low-permeability reservoir foam oil displacement agent solution into a stirring cup by adopting an OWC-9360 constant-speed stirrer, and introducing CO 2 Stirring the gas for 60s at a constant rotating speed of 10000r/min, and immediately detecting the gas, wherein the detection is as follows:
reading the initial foam volume V 0 And start timing; the time t required for half of the foam to disappear was recorded 1/2 Namely, the foam half-life period is obtained, and finally the foam comprehensive index FCI is calculated (FCI =0.75 xV) 0 ×t 1/2 )。
The foam oil displacement agent suitable for the high-salinity low-permeability oil reservoir and the application thereof are as follows: preparing foam by the ultra-low interfacial tension foam oil displacement agent through a sand-packed pipe model, and specifically operating as follows: adding the ultra-low interface tension foam oil displacement agent into a piston container; the lower end of the piston container is connected with the double-cylinder pump, the upper end of the piston container is connected with the inlet end of the sand filling pipe through a three-way valve, and CO 2 The high-pressure gas cylinder is connected with the inlet end of the sand filling pipe through a three-way valve; the outlet end of the sand filling pipe is sequentially connected with the soap foam flowmeter and the foam test tube; with CO 2 The high-pressure gas cylinder is connected into the upper space of the piston container and is filled with CO 2 Gas and CO retention 2 The high-pressure gas cylinder has equal pressure; the output flow of the double-cylinder pump is 1mL/min, the gas-liquid ratio is 1.5; the sand filling pipe is filled with 80-100 meshes of quartz sand, and the double-cylinder pump is an ISCO constant-pressure constant-flow double-cylinder pump.
The foam oil displacement agent suitable for the high-salinity low-permeability oil reservoir and the application thereof are as follows: carrying out a core oil displacement experiment on a low-permeability core by using an ultra-low interfacial tension foam oil displacement agent, and specifically operating as follows: putting the rock core of the saturated high-salinity formation water into a rock core holder, loading, applying confining pressure, checking the tightness of the system, and continuing the experiment if the tightness is good; injecting crude oil into the rock core through the intermediate container until all crude oil flows out of the outlet, and establishing original oil saturation; water flooding crude oil is driven to the economic limit (the water content is stabilized to 98%), a water flooding oil reservoir model is built, and the water flooding recovery ratio is calculated; and opening a valve, connecting foam prepared by the sand filling pipe, injecting 0.5PV ultra-low interfacial tension foam to displace crude oil, after the foam slug is completely injected, subsequently driving water to an economic limit, and calculating the ultra-low interfacial tension foam oil displacement agent to improve the crude oil recovery ratio.
In the formula of the foam oil displacement agent suitable for the high-salinity low-permeability oil reservoir, the surfactant concentration is low, the foam oil displacement agent can be self-assembled to form a composite worm-shaped micelle under the action of a counter ion compound, and the contour length of the composite worm-shaped micelle can be 500 nanometers or even 100 micrometers; in the solution, when the composite worm-like micelles reach a certain length and density, the micelles begin to intertwine and overlap with each other to form a network structure with viscoelasticity. Different from the existing polymer solution, the polymer is a long-chain molecular structure connected together by covalent bonds, and the composite worm-like micelle is a molecular ordered assembly formed by aggregation of small molecules under the action of intermolecular force. The dissociation and recombination process exists between the compound wormlike micelle formed by the surfactant molecules and the small molecule surfactant, so that the whole system is a dynamic and balanced network structure. Compared with patent CN110776893A and patent ZL201710864250.3, the counter ions of the invention have smaller molecular weight, and the composite wormlike micelles formed by self-assembly are longer, and macroscopically show that the viscosity is higher under the same dosage. The formation of the composite vermicular micelle can effectively prevent the generation of calcium carbonate crystal nucleus and the growth of crystal, the extrusion of calcium and magnesium ions on the composite vermicular micelle causes the thinning of an electric double layer, the hydromechanics of the composite vermicular micelle is reduced, the size is reduced, the generated foam is fine and uniform, the stability is good, and the foam with the diameter of 1-20um is generated after foaming. Meanwhile, due to the synergistic effect of the trimeric betaine surfactant and the amine oxide type nonionic surfactant, surfactant molecules are more tightly arranged on an oil-water interface, the oil-water interfacial tension is reduced more strongly, and the oil-water interfacial tension can reach an ultralow value or even lower value.
The invention has the advantages that:
(1) The foam oil-displacing agent is trimeric betaine surfactant tris [ (N-dodecyl-N-ethyl-N-carboxymethyl sodium) -2-ammonium bromide ethylene group]The amine and the sodium salicylate can form a compound wormlike micelle in saline water, and the compound wormlike micelle has certain viscosity. The same amount was added under the same conditions and the viscosity formed with the sodium salicylate system was much greater than the viscosity formed with the sodium lauryl sulfate system. Introducing CO 2 After foaming, the generated foam is rich and fine, the diameter size is between 1 and 20 mu m, and the half-life period is longer; CO injection in extended oil field reservoirs with high salinity 2 During foaming, the foam is acid resistant and salt resistant, the foam system does not generate precipitation with calcium and magnesium ions, has good foamability and foam stability, and can ensure that the oil-water interfacial tension reaches 10 -3 Of the order of mN/m or even lower.
(2) The foam oil displacement agent does not contain alkali and polymer, so that the problems of reduction of viscoelasticity of a system, precipitation of alkali and formation water, increase of injection process and treatment difficulty of produced liquid, increase of cost and the like caused by application of alkali are solved, and the defects that the use of polymer is too large in molecular weight, the hydraulic radius of a non-substituted coil formed after the polymer is dissolved in the formation water is large, and the polymer is difficult to inject into a long and thin pore throat in a low-permeability oil reservoir are overcome;
(3) The foamed foam obviously reduces the oil-water interfacial tension, improves the oil washing efficiency, increases the formation energy and improves the sweep capacity of the fluid by improving the fluidity ratio, thereby improving the recovery ratio of the low-permeability reservoir.
Detailed Description
The formation water mineralization for the specific examples is shown in table 1.
TABLE 1 formation water mineralization degree
Example 1
1. A foam oil displacement agent suitable for a high-salinity low-permeability oil reservoir comprises the following components in percentage by weight:
tris [ (N-dodecyl-N-ethyl-N-carboxymethyl sodium) -2-ammoniumbethylene bromide ] amine: 0.4 percent of the total weight of the mixture,
nonionic surfactant dodecyl dimethyl amine oxide (0B-2): 0.1 percent of the total weight of the mixture,
sodium salicylate: 0.03 percent of the total weight of the mixture,
the chelating agent is EDTA:0.14 percent of the total weight of the mixture,
formation water mineralization degree: 89542mg/L of the active carbon,
the balance of water, the total amount is 100 percent,
wherein the structure of the tri [ (N-dodecyl-N-ethyl-N-carboxymethyl sodium) -2-ammonium ethylene bromide ] amine is
The tri [ (N-dodecyl-N-ethyl-N-carboxymethyl sodium) -2-ammonium bromide ethylene ] amine is a hydroxyl sulfobetaine type Gemini surfactant.
The tris [ (N-dodecyl-N-ethyl-N-carboxymethyl sodium) -2-ammonium ethylene bromide ] amine is a surfactant in the prior art, and the preparation method is shown in a paper of synthesis and performance evaluation of tris [ (N-dodecyl-N-ethyl-N-carboxymethyl sodium) -2-ammonium ethylene bromide ] amine, a chemical reagent and 2016, which are published by ZhouMing subject group.
Example 2
2. A foam oil displacement agent suitable for a high-salinity low-permeability oil reservoir comprises the following components in percentage by weight:
tris [ (N-dodecyl-N-ethyl-N-carboxymethyl sodium) -2-ammoniumbethylene bromide ] amine: 0.5 percent of the total weight of the mixture,
nonionic surfactant dodecyl dimethyl amine oxide (0B-2): 0.2 percent of the total weight of the mixture,
the chelating agent is EDTA:0.04 percent of the total weight of the mixture,
formation water mineralization degree: 89542mg/L of the total weight of the powder,
the balance of water, the total amount is 100 percent,
wherein, the structural formula and the preparation method of the tris [ (N-dodecyl-N-ethyl-N-carboxymethyl sodium) -2-ammonium ethylene bromide ] amine are the same as those of the embodiment 1;
example 3
3. A foam oil displacement agent suitable for a high-salinity low-permeability oil reservoir and an application thereof comprise the following components in percentage by weight:
tris [ (N-dodecyl-N-ethyl-N-carboxymethyl sodium) -2-ammonium ethylene bromide ] amine: 0.6 percent of the total weight of the mixture,
nonionic surfactant dodecyl dimethyl amine oxide (0B-2): 0.35 percent of the total weight of the mixture,
the chelating agent is EDTA:0.10 percent of the total weight of the mixture,
formation water mineralization degree: 89542mg/L of the active carbon,
the balance of water, the total amount is 100 percent,
wherein, the structural formula and the preparation method of the tris [ (N-dodecyl-N-ethyl-N-carboxymethyl sodium) -2-ammonium ethylene bromide ] amine are the same as those of the embodiment 1;
preparation method, performance detection and application
1. Foams suitable for the high-salinity low-permeability oil reservoirs in the examples 1 to 3 are respectively prepared according to the following preparation methods:
(1) Heating formation water to 70 ℃ (the specific cation and anion concentrations of the mineralization of the formation water are shown in table 1), adding tris [ (N-dodecyl-N-ethyl-N-carboxymethyl sodium) -2-ammonium ethylene bromide ] amine, and stirring to dissolve;
(2) And (2) sequentially adding a nonionic surfactant dodecyl dimethyl amine oxide and a chelating agent into the mixed solution obtained in the step (1), and stirring for dissolving.
(3) And (3) adding sodium salicylate into the mixed solution obtained in the step (2), and stirring for dissolving.
2. Performance detection and application
(1) The mixed solution obtained in the step (3) was measured for the viscosity of the ultra-low interfacial tension foam oil-displacing agent by means of a Brookfield VIII viscometer, and the interfacial tension was measured by means of a Tax500 ultra-low rotary interfacial tensiometer, and the results are shown in Table 2.
(2) Adding foam oil displacement agent with ultralow interfacial tension into a stirring cup by adopting an OWC-9360 constant speed stirrer, and introducing CO 2 Gas, stirring for 60s at a constant rotation speed of 10000r/min, and immediately reading the initial foam volume V 0 And starting timing; the time t required for half of the foam to disappear was recorded 1/2 Namely, the foam half-life is obtained, and finally, the foam comprehensive index FCI is calculated (FCI =0.75 xV) 0 ×t 1/2 ) The results are shown in Table 2.
TABLE 2 influence of viscosity, interfacial tension, foamability and half-life of foam oil-displacing agent
Compared with the patent ZL201710864250.3, the patent does not use triethanolamine and urea; under the same conditions of other dosage and conditions, two patent examples 1, 2 and 3 of the invention are compared one-to-one: the viscosity of the product of patent example 1 is 5.7mPa.s higher than that of the product of patent ZL201710864250.3, the foaming volume is increased by 8mL, the half-life period is increased by 10min, and the foam comprehensive index FCI is increased by 4398mL.min; the viscosity of the foam of the embodiment 2 of the patent is improved by 8.2mPa.s, the foaming volume is increased by 25mL, the half-life period is increased by 6min, and the foam comprehensive index FCI is increased by 2408mL.min; the viscosity of the foam of the patent in example 3 is improved by 13.2mPa.s, the foaming volume is increased by 160mL, the half-life period is increased by 6min, and the foam comprehensive index FCI is increased by 4920mL.min; compared with the patent ZL201710864250.3, the viscosity of the foam oil displacement agent and the foam comprehensive index FCI are obviously increased.
Aiming at prolonging crude oil in an oil field, the invention patent ZL201710864250.3 does not measure the oil-water interfacial tension, three examples of the invention are measured under the experimental condition of the patent, and the oil-water interfacial tension of the invention patent ZL201710864250.3 does not reach 10 -3 mN.m -1 Magnitude order (ultra-low value), and the oil-water interfacial tension of patent examples 1 and 2 of the invention reaches 10 -3 mN.m -1 Order of magnitude, while the oil-water interfacial tension of example 3 is lower, reaching 10 -4 mN.m -1 The oil displacement agent disclosed by the invention has stronger capability of reducing the tension of an oil-water interface.
Under the condition that the surfactant and the assistant used in the invention patent are far smaller than those in the invention patent CN110776893A, the oil displacement agent of the invention patent reduces the oil-water interfacial tension lower than that of the invention patent CN110776893A, and has better foaming volume.
(3) Preparing foam by using the foam oil displacement agent with ultralow interfacial tension through a sand filling pipe, and specifically operating as follows: adding the foam oil displacement agent with ultra-low interfacial tension into a piston container; the lower end of the piston container is connected with the double-cylinder pump, the upper end of the piston container is connected with the inlet end of the sand filling pipe through a three-way valve, and CO 2 The high-pressure gas cylinder is connected with the inlet end of the sand filling pipe through a three-way valve; the outlet end of the sand filling pipe is sequentially connected with the soap foam flowmeter and the foam test tube; with CO 2 The high-pressure gas cylinder is connected into the upper space of the piston container and is filled with CO 2 Gas and CO Retention 2 The high-pressure gas cylinder is used for equalizing pressure; the output flow of the double-cylinder pump is 1mL/min, the gas-liquid ratio is kept at 1.5; the sand filling pipe is filled with 80-100 meshes of quartz sand, and the double-cylinder pump is an ISCO constant-pressure constant-flow double-cylinder pump.
(4) Carrying out core oil displacement on the ultra-low interfacial tension foam oil displacement agent by the following specific operations: putting the rock core of the saturated high-salinity formation water into a rock core holder, loading, applying confining pressure, checking the tightness of the system, and continuing the experiment if the tightness is good; injecting crude oil into the rock core through the intermediate container until all crude oil flows out of the outlet, and establishing original oil saturation; water flooding crude oil is driven to the economic limit (the water content is stabilized to 98%), a water flooding oil reservoir model is built, and the water flooding recovery ratio is calculated; and opening a valve, introducing foam prepared by the sand filling pipe in front, injecting 0.5PV ultra-low interfacial tension foam to displace crude oil, after the foam is injected, subsequently driving water to the economic limit, and calculating the ultra-low interfacial tension foam oil displacement agent to improve the crude oil recovery rate. Core parameters of the cores used in examples 1-3 are shown in table 3, and displacement experiment results of the ultra-low interfacial tension foam displacement agents used in examples 1-3 are shown in table 4.
TABLE 3 basic parameters of the experimental cores
TABLE 4 ultra low interfacial tension foam flooding test results
Under the condition that the total dosage (0.56-1.16%) of main agents (including tris [ (N-dodecyl-N-ethyl-N-carboxymethyl sodium) -2-ammonium bromide ethylene group ] amine, dodecyl dimethyl amine oxide, sodium salicylate and chelating agent EDTA) used by the invention patent is far less than the total dosage (30-80%) of main agents (anionic and cationic surfactants, betaine type surfactants and nonionic surfactants) of the invention patent CN110776893A, the minimum oil displacement efficiency and the maximum oil displacement efficiency in the invention patent are respectively 26.9% and 32.8%, and are 10.7% and 12.1% higher than the minimum efficiency and the maximum oil displacement efficiency in nine embodiments of the invention patent CN110776893A, so that the invention has higher oil displacement capacity.
Claims (5)
1. The foam oil displacement agent suitable for the high-salinity low-permeability oil reservoir is characterized in that: the weight percentage of the components is as follows:
tris [ (N-dodecyl-N-ethyl-N-carboxymethyl sodium) -2-ammonium ethylene bromide ] amine: 0.4-0.6%, nonionic surfactant: 0.1 to 0.35 percent of,
counter-ionic compound: 0.02 to 0.07 percent of the total weight of the mixture,
chelating agent: 0.04-0.14 percent of the total weight of the mixture,
inorganic salts: 6-10% of the total weight of the composition,
the balance of water,
wherein the structural formula of the tri [ (N-dodecyl-N-ethyl-N-carboxymethyl sodium) -2-ammonium ethylene bromide ] amine is as follows:
the trimeric betaine type surfactant is characterized in that the nonionic surfactant is dodecyl dimethyl amine oxide, and the counter ion compound is sodium salicylate.
2. The foam oil displacement agent suitable for the hypersalinity low-permeability reservoir according to claim 1, characterized in that: the chelating agent is EDTA.
3. The foam oil displacement agent suitable for the hypersalinity hypotonic oil reservoir according to claim 1, characterized in that: the inorganic salt is any one or more of sodium chloride, magnesium chloride, sodium sulfate, sodium bisulfate, sodium carbonate, potassium chloride and calcium chloride.
4. The foam oil displacement agent suitable for the hypersalinity low-permeability reservoir according to claim 1, characterized in that: the preparation method of the foam oil displacement agent suitable for the high-salinity low-permeability oil reservoir comprises the following steps:
(1) Heating water to 70 ℃, adding inorganic salt, adding tris [ (N-dodecyl-N-ethyl-N-carboxymethyl sodium) -2-ammonium ethylene bromide ] amine, and stirring for dissolving;
(2) Sequentially adding a nonionic surfactant dodecyl dimethyl amine oxide and a chelating agent EDTA into the mixed solution obtained in the step (1), and stirring for dissolving;
(3) And (3) adding sodium salicylate into the mixed solution obtained in the step (2), and stirring for dissolving.
5. The foam oil displacement agent suitable for the hypersalinity hypotonic oil reservoir according to claim 1, characterized in that: the interfacial tension of the foam oil displacement agent suitable for the high-salinity low-permeability oil reservoir can reach 2.5 multiplied by 10 -4 mN/m, the foam flooding improves the recovery ratio by 32.8 percent.
Priority Applications (1)
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