55results about How to "Improve mobility ratio" patented technology

The invention discloses a low-tension viscosity-reducing oil displacement agent, which is used for common heavy oil reservoirs, has a good viscosity-reducing effect, has good compatibility with formation water, can form ultra-low interfacial tension with crude oil, and is prepared from the following components by weight: 30-50% of an alkyl alcohol polyoxyethylene ether sulfate salt, 15-25% of a nonionic surfactant, 15-25% of an anionic surfactant, 2-5% of an organic solvent, 0.1-3% of sodium chloride, and 5-25% of water. According to the present invention, during the use, the low-tension viscosity-reducing oil displacement agent and the polyacrylamide polymer form the composite oil displacement system, wherein the polyacrylamide polymer can provide effects of water phase viscosity increasing, water-oil mobility ratio reducing, conformance expanding and profile control expanding, and the low-tension viscosity-reducing oil displacement agent can provide effects of oil-water interface tension reducing, oil displacement efficiency improving and crude oil viscosity reducing so as to further improve the water-oil mobility ratio, such that the extraction rate of the common heavy oil reservoir can be substantially improved through the synergetic effect of the polyacrylamide polymer and the low-tension viscosity-reducing oil displacement agent.

The invention relates to a method of displacing oil by anionic-cationic composite surfactant and mainly solves the problems that the prior method of displacing oil by surfactant is low in oil displacement efficiency in tertiary oil recovery and an oil displacement system containing inorganic base is harmful to stratums and oil wells, corrosive to equipment and pipelines and difficult for demulsification. According to the technical scheme, crude oil is allowed to contact with oil-displacing agent, and the oil-displacing agent comprises, by weight percent, 0.01-5.0% of anionic-cationic composite surfactant, 0.01-3.0% of polymer, and 92.0-99.98% of injected water. The problems are solved well. The method is applicable to tertiary oil recovery for oil fields.

The invention provides a cross-linked polymer microsphere-polymer composite deep water control agent and a using method thereof. The control and drive agent includes water-soluble cross-linked polymer microspheres, water-soluble polymers and water; in the composite deep-seated control and drive agent, the mass percentage of the water-soluble cross-linked polymer microspheres is 0.01% to 0.3%, The mass percent content of the water-soluble polymer is 0.05%-0.5%, and the balance is water. The cross-linked polymer microsphere-polymer composite deep control and flooding agent provided by the present invention has a higher liquid flow redirection ability than conventional polymer flooding, can delay the one-way breakthrough of the polymer solution in the application process, and improve the efficiency of polymer flooding. The sweep coefficient has a higher ability to improve the oil-water phase mobility ratio than the conventional cross-linked polymer solution, and improves the displacement ability of the cross-linked polymer solution, which is more suitable for water injection development reservoirs with heterogeneous porous media.

The invention relates to a method for increasing the recovery ratio of a tight oil reservoir through CO2 foam huff and puff. The method comprises the steps that high-pressure CO2 is injected into the fractured tight oil reservoir for slugging, cracks are mainly filled with CO2 for soaking, and crude oil enters the cracks from the matrix under the actions such as extraction, volume expansion and dissolution and viscosity reduction; and after the pressure of a wellhead is stable, a well is opened for production, in the formation seepage process, CO2 makes contact with a surface active agent aqueous solution to generate foam, the CO2 foam displaces the crude oil so that the crude oil can flow from the cracks to a shaft, and finally the crude oil is recovered to the ground. According to the method, no foam is generated in the CO2 injection process, and the situation that the generated CO2 foam displaces the crude oil to the deep position of the oil reservoir is prevented; and in the recovery process, the CO2 makes contact with the surface active agent aqueous solution so that the foam can be generated in the stratum, through the mechanisms that the CO2 foam conducts oil cleaning in the cracks and the fluidity of CO2 is effectively controlled, more crude oil in the cracks can be displaced into the shaft, and the recovery ratio of the tight oil reservoir is increased.

The invention relates to a composite profile control and oil displacement extraction method for a thickened oil reservoir through water injection and exploitation. The method provided by the invention comprises the following steps: preparing a polymer and water into a polymer solution with the concentration of 500-5000mg / L; preparing a cross-linking agent and water into a cross-linking agent solution with the concentration of 500-5000mg / L; mixing the polymer solution and the cross-linking agent solution according to the mass ratio of (1:1)-(10:1) to obtain a polymer gel solution; preparing a movable micro-gel and water into a movable micro-gel solution with the concentration of 1000-5000mg / L; respectively injecting the polymer gel solution and the movable micro-gel solution into a well to form an oil displacement segmentation plug, wherein the polymer is partial hydrolysis polyacrylamide; the cross-linking agent is an organic chromium cross-linking agent; and the movable micro-gel is a copolymer of acrylamide and N-N methylene bisacrylamide. The method provided by the invention can obviously improve the anisotropism in storage layers, among the layers and on planes, relieves the water injection and exploitation contradictions of the oil reservoir, solves the problems of tonguing and fingering and obviously enlarges the swept volume of a displacing solution, thereby greatly improving the recovery ratio of crude oil.

The invention discloses a compound microorganism oil extraction method for a low permeability oilfield. The compound microorganism oil extraction method comprises the following steps of (1) cultivating pseudomonas aeruginosa YM4 strains and pseudomonas stutzeri DP1 strains in an indoor shaking flask respectively, and obtaining fermentation broth of high-activity pseudomonas aeruginosa YM4 strains and fermentation broth of polymer produced strains through first-stage and second-stage seeding tank amplification and fermentation production of a production tank; (2) mixing surface active agent produced strains and the pseudomonas stutzeri DP1 strains fermented and produced in the step (1) according to volume ratio of 1:1; and (3) enabling compound microorganism bacterium liquid obtained in the step (2) to serve as an oil-displacing agent to inject in an oil layer directly through a water injection well, and obtaining crude oil from a producing well. The YM4 strains and the DP1 strains are both facultative anaerobic microorganisms and can both grow and breed in a ground layer, polymers produced by the DP1 strains can improve mobility ratio, increases water injection affecting area, and the product surface active agent of the YM4 strains can reduce oil-water interfacial tension and improve oil recovery.

The invention discloses a high-recovery-ratio tertiary oil recovery displacement agent which comprises the following raw materials in parts by weight: 1-2 parts of polyacrylamide, 0.4-0.6 part of modified nano silicon dioxide, 6-8 parts of a surfactant, 0.5-1 part of sodium carbonate and 100-150 parts of water. By compounding the modified nano silicon dioxide with the proper surfactant, the compatibility of the two-phase interface is improved, so that the dispersed phase is not easy to condense, the stability of the emulsion is improved, the capillary resistance is reduced, the oil-water interfacial tension is greatly reduced, and the recovery ratio is improved. Furthermore, through mutual cooperation of the other substances, the temperature resistance, the salt resistance and the recoveryratio of the tertiary oil recovery oil displacement agent are further improved.

The invention relates to the technical field of oil extraction of oil fields, in particular to a diversified carbon-dioxide flooding oil extraction method. By adjusting parameters including minimum mixed-phase pressure, injection ratio, injection pressure, injection speed and the like of liquid carbon dioxide and water and utilizing alternative injection and flooding of the carbon dioxide and the water to perform crude oil extraction, the oil extraction speed and the recovery efficiency are improved.

The invention provides a high-efficiency air foam oil displacement system. The high-efficiency air foam oil displacement system is characterized in that the high-efficiency air foam oil displacement system is prepared by return water of oilfields, and is prepared by the following raw materials in percent by mass: 0.12% of perfluorocarbon 101005 foaming agents, 0.08% of dodecyl phosphate hydroxypropyl betaine, 0.1% of surfactant BS betaine, and the balance partially hydrolyzed polyacrylamide. The oil displacement system has excellent adaptation on high-salinity and high-oil sewage returned from the oilfields, is high in compatibility, high in salt tolerance and excellent in foaming characteristic and stability; a displacement section can be effectively adjusted; interfacial tension is reduced; swept volume is increased; and recovery efficiency of the oilfields is improved.

The invention provides an active pre-crosslinking gel particle and a preparation method thereof. The active pre-crosslinking gel particle is prepared from the components of acrylamide, anionic monomer, 3-alkyl-4-styrene fatty alcohol polyoxyethylene alkyl ether sodium sulfonate, N, N-methylene diacrylamide, tetramethyl ethylenediamine and deionized water. The preparation method comprises the steps of initiating polymerization crosslinking of the acrylamide and the anionic monomer by an initiator, and carrying out physical means of cutting, pelletizing, drying, crushing and the like to prepare the active pre-crosslinking gel particle finally. With the adoption of the active pre-crosslinking gel particle, as the 3-alkyl-4-styrene fatty alcohol polyoxyethylene alkyl ether sodium sulfonate is added in the active pre-crosslinking gel particle, a single component of polymer has the interfacial activity and the emulsifying property; when the active pre-crosslinking gel particle is taken as a profile control agent, the plugging rate reaches 72.56 percent.

The invention discloses a viscoelastic particle oil displacement agent with a water plugging function. The agent comprises, according to weight percentage, 15%-25% of acrylic acid; 10%-15% of acrylamide, 0.01-0.04% of a cross-linking agent and 0.03-0.06% of an initiator, and the method comprises the steps: uniformly mixing the components in water, heating to 60-70 DEG C, keeping the temperature constant for 2-3 hours, heating to 80-90 DEG C, keeping the temperature constant for 2-3 hours, adding 50-80% of silicon dioxide gel, and mixing and dispersing to obtain bead-shaped particles with different particle sizes. The viscoelastic particle oil displacement agent has a partially crosslinked and partially branched molecular structure; the oil displacement agent has certain viscoelasticity andcan be dispersed in water to form a heterogeneous suspension, the suspension is a flowable viscoelastic and deformable material, has good pumpability and injectability, and has better sweep efficiency and oil displacement efficiency for a strong heterogeneous oil layer.

The invention relates to a composite oil displacement agent, and belongs to the technical field of crude oil exploitation. Through in-situ polymerization and mechanical blending of diatomite and dimerfatty acid, an adsorption effect on oily components is provided, molecular chain movement is weakened, the stability in the oil displacement process is improved, the temperature resistance and interface stability of the oil displacement agent can be effectively improved, and the viscosity of thickened oil is reduced; lignite and metakaolin are treated, a mixed monomer is grafted, the interfacialtension between the oil displacement agent and crude oil is reduced through the synergistic effect of various raw materials, and the oil washing capacity of the oil displacement agent is improved. According to the invention, the defects of poor temperature resistance, poor interface stability and the like of a conventional common oil displacement agent are overcome, and the problem of unobvious viscosity reduction effect on thickened oil is solved.

The invention discloses a method for increasing oil recovery of heavy oil reservoirs through a composite heat carrier, and particularly relates to a method for increasing oil recovery of heavy oil reservoirs through a composite heat carrier composed of hot water, a gas and a chemical agent. According to the method, crude oil recovery is increased, by injecting hot water and flue gas generated by boiler burning together into an oil layer, and by injecting a foaming agent by means of slug injection. The method includes the steps of a, injecting a mixture of hot water and flue gas 0.15-0.2 times the pore volume of a formation; b, injecting foaming agent solution into a water injection well for 25-30 d; c, injecting the hot water and flue gas mixture for 60-80 d; d, repeating the steps b and c. Water (vapor) can be effectively blocked from channeling, vapor wave and volume are increased, heavy oil recovery is substantially increased, and as the flue gas generated by burning is injected directly underground, heat efficiency can be improved and environmental pollution can also be reduced.

The invention provides a temperature-resistant and salt-resistant multi-component copolymerization pre-crosslinked gel particle and a preparation method and application thereof, and belongs to the technical field of oil exploitation, transportation and chemical engineering. The pre-crosslinked gel particle is formed by copolymerization of acrylamide and 2-acrylamide-2-methylpropanesulfonic acid, is stable in copolymer structure, relatively good in high-temperature aging resistance, not easy to hydrolyze and good in compatibility with a polymer, greatly improves the viscosity of the system, andimproves the suspension performance of the pre-crosslinked gel particles in the system, and thus the oil displacement capacity of the system is higher, and the oil displacement efficiency is higher.

The invention relates to an amphoteric cross-linked polymer microsphere-hydrophobic associative polymer profiling / flooding agent and an application thereof. The profiling / flooding agent comprises 0.01-0.5% of amphoteric cross-linked polymer microspheres, 0.01-0.5% of water-soluble hydrophobic associative polymer and balance of water. The amphoteric cross-linked polymer microspheres are prepared through a polymerization reaction in an inert environment. In the reaction system of the polymerization reaction, polymerization monomers account for 1.0-40% of the reaction system by mass; cross-linking monomer accounts for 0.001-3% of the reaction system by mass; the polymerization monomers are anionic monomer, cationic monomer and nonionic monomer, wherein a molar ratio of the anionic monomer to the cationic monomer to the nonionic monomer to the cross-linking monomer is 2.5-25: 2.5-25: 50.0-95: 0.1-6. With the composite deep profiling / flooding agent provided by the invention, water injected reservoir recovery rate can be substantially improved. The profiling / flooding agent is more suitable for waterflooding reservoirs with nonuniform porous media.

The invention provides a high permeability reservoir oil displacement system. The system comprises an association polymer. The association polymer has molecular weight of 1.987 to 40.215 million. The association polymer is prepared from acrylamide, 0.11%-9.96% by mole of a hydrophobic monomer and 0-14.79% by mole of a functional monomer through polymerization. The oil displacement system has an association polymer concentration of 400-3500 mg / L. Compared with the existing oil displacement system, the high permeability reservoir oil displacement system utilizes the association polymer obtained by introducing a small amount of the hydrophobic monomer and functional monomer to the polymer molecular chain, and the hydrophobic groups are associated in an aqueous solution to form a space network structure so that system viscosity is improved and a real high-resistance coefficient and a high residual resistance coefficient are built. Through use of the functional monomer and the space network structure, the system has good temperature, salt and shear resistance and aging stability, improves oil-water mobility of high permeability reservoir, improves injection water wave and efficiency and well improves high permeability reservoir recovery efficiency.

The invention relates to an ultra-low-permeability oilfield selective weak gel oil displacement profile control agent. The ultra-low-permeability oilfield selective weak gel oil displacement profile control agent is prepared from the following components in parts by mass: 0.1 to 1.0 part of anionic polyacrylamide, 0.01 to 0.2 part of an aluminum ion organic salt compound crosslinking agent, 0.005to 0.1 part of an organic sulfide crosslinking initiator and the balance of water, wherein the total amount of the raw materials is 100 parts. The ultra-low-permeability oilfield selective weak gel oil displacement profile control agent provided by the invention is applicable to low-permeability oil deposit strata and has high mineralization resistance, good thermal stability and controllable system gel-forming time; the ultra-low-permeability oilfield selective weak gel oil displacement profile control agent can enter deep parts of the strata through an ultra-low-permeability oil deposit pore-throat channel, can be used for effectively plugging water outlet large pore channels of the deep parts of the ultra-low-permeability oil deposit strata and has dual effects of profile control and oil displacement.

The invention discloses an efficient compound oil displacement agent. The oil displacement agent is prepared from the following raw materials: lignosulfonate, fatty alcohol polyoxyethylene ether sulfonate, xanthan gum, a dimeric surfactant, an anion surfactant, an organic solvent and water. According to the oil displacement agent disclosed by the invention, alkali is not added, so that damages, caused by alkali, on a stratum are reduced and sustainable exploitation of an oilfield is facilitated; the oil displacement agent disclosed by the invention has good thermal stability and high temperature resistance; when the temperature of the stratum is 130 DEG C, the oil displacement agent is not muddy and has no sediment; the effect of reducing interface tension can be effectively expressed andthe anion surfactant and the dimeric surfactant are compounded so that the oil displacement agent can be used for low-pressure and low-permeability oilfields; the oil displacement agent disclosed by the invention can be tightly combined with a sulfur-containing component in thick oil, and moistening and reversed transformation, and crude oil viscosity reduction effects can be expressed better, sothat the viscosity of the thick oil can be remarkably reduced under a utilization condition of relatively low concentration and the recovery ratio is improved.

The invention discloses a compound microorganism oil extraction method for a low permeability oilfield. The compound microorganism oil extraction method comprises the following steps of (1) cultivating pseudomonas aeruginosa YM4 strains and pseudomonas stutzeri DP1 strains in an indoor shaking flask respectively, and obtaining fermentation broth of high-activity pseudomonas aeruginosa YM4 strains and fermentation broth of polymer produced strains through first-stage and second-stage seeding tank amplification and fermentation production of a production tank; (2) mixing surface active agent produced strains and the pseudomonas stutzeri DP1 strains fermented and produced in the step (1) according to volume ratio of 1:1; and (3) enabling compound microorganism bacterium liquid obtained in the step (2) to serve as an oil-displacing agent to inject in an oil layer directly through a water injection well, and obtaining crude oil from a producing well. The YM4 strains and the DP1 strains are both facultative anaerobic microorganisms and can both grow and breed in a ground layer, polymers produced by the DP1 strains can improve mobility ratio, increases water injection affecting area, and the product surface active agent of the YM4 strains can reduce oil-water interfacial tension and improve oil recovery.

The invention provides an ultralow interfacial tension self-assembly carbon dioxide foam oil displacement agent suitable for a low-permeability reservoir. The oil displacement agent is prepared from the following components in percentage by weight: 0.2-0.3% of {bis [N-methyl-N-(3-dodecyloxy-2-hydroxyl) propyl-N-(2-hydroxy-3-sodium sulfonate) propyl] ammonium chloride} ethane, 0.2-0.3% of cocamidopropyl betaine, 0.2-0.3% of sodium dodecyl benzene sulfonate and the balance of water. The cleaning agent is prepared from the following components in percentage by weight: 0.1 to 0.35 percent of dodecyl dimethyl amine oxide, 0.02 to 0.07 percent of sodium salicylate, 0.04 to 0.14 percent of chelating agent, 5 to 7 percent of inorganic salt and the balance of water. The invention also provides a preparation method and application of the self-assembled carbon dioxide foam oil-displacing agent with ultralow interfacial tension. The self-assembled carbon dioxide foam oil-displacing agent is good in salt resistance and acid resistance and high in foaming liquid viscosity, enables oil-water interfacial tension to reach 10 <-3 > mN / m order of magnitude and below, generates fine and rich foam, is good in stability, is good in injectability in a low-permeability reservoir, and can improve the oil-water mobility ratio, remarkably increase the sweep efficiency, reduce the oil-water interfacial tension and remarkably improve the oil washing efficiency; the foaming agent does not generate a salting-out phenomenon, and does not generate chemical reaction with calcium and magnesium ions to generate precipitates.

The invention relates to a device and method for improving oil field recovery efficiency. A carbon dioxide oil displacement technology is applied to the development of tight oil, so that the oil displacement effect is improved, carbon dioxide can be well sealed underground, and the greenhouse gas effect in the atmosphere is reduced. The carbon dioxide can reduce the viscosity of crude oil, improvea mobility ratio, expand swept volume, and effectively solve development contradictions of ultra-low permeability reservoirs such as no water injection, insufficient water injection, difficulty in establishing an effective displacement system and channeling of injected water along fractures. The carbon dioxide and underground crude oil are mixed with each other (miscible), the characteristics oflow miscible pressure, low interfacial tension and the like are realized, on average, a recovery ratio of the oil field is increased by 5% to 15% on the basis of water flooding, and the oil displacement efficiency is improved.

The invention discloses a method for improving the CO2 flooding effect of a low-permeability reservoir. The method for improving the CO2 flooding effect of the low-permeability reservoir comprises thefollowing steps: step 1, a gel particle suspension is injected, gel particle suspension pre-slugs are injected into an oil layer, and the injection amount occupies 4%-6% of the percentage by volume,of a daily total injection amount; and step 2, alternating injection is carried out, polymeric microsphere solution slugs and CO2 flooding slugs are injected into the oil layer in an alternating manner, and the injection amount occupies 94%-96% of the percentage by volume, of the daily total injection amount. The gel particle suspension comprises, in percentage by mass, 0.05%-0.10% of polyacrylamide, 0.5%-1.0% of gel particles and the balance water; and a polymeric microsphere solution comprises, in percentage by mass, 0.1%-0.2% of polymeric microspheres and the balance water. In a polymeric microsphere system, a 2-acrylamide-2-methylpropane sulfonic acid AMPS monomer is introduced, so that the salt-resistant and acid-resistant performance is optimized, the utilization rate of subsequently-injected CO2 is increased, the swept volume of the CO2 is increased, and the CO2 flooding effect is improved.

The invention provides a preparation method and application of a double-braid polymer surfactant containing long carbon chains. The double-braid polymer surfactant has a structure as shown in formula(I), wherein x is 1-30; m / (m + n + p) * 100% = 90.3%-94.45%; n / (m + n + p) * 100% = 5.5%-9.5%; p / (m + n + p) * 100%=0.05%-0.2%. The surfactant provided by the invention enables thickened oil to form astable oil-in-water emulsion under the condition of low stratum shear, so that the purpose of viscosity reduction is achieved; certain tackifying performance on water phase is achieved, under the synergistic effect of the two components, the oil-water fluidity ratio is improved, so that the swept volume is enlarged, and the water drive recovery rate of the thickened oil is increased.

The invention discloses a preparation method and an application process of an oil washing agent. A base solution is prepared from the following components by weight percent: 10-15% of A, 5-10% of B, 15-20% of C, 5-10% of D, 5-10% of E, 5-10% of F, 5-10% of G, 5-10% of H and 10-20% of water. A preparation method of the base solution of the oil washing agent comprises the following steps: adding F and G into a stirring tank with a heating function according to the proportion; sequentially adding A, B, C, D and E into the stirring tank while stirring, and heating for complete dissolution; and finally, adding H, controlling the temperature at 80+ / -5 DEG C, and performing heat preservation for 1 hour to obtain the base solution. The oil washing agent is obtained by preparing the base solution into 1% of aqueous solution with 4% of NaCl and 0.1% of CaCl2 solution, and curing the aqueous solution in water bath at 90 DEG C for 24 hours. The application process of the oil washing agent adopts an oil recovery method of combining the oil washing agent with the CO2 huff-puff technology; the oil washing efficiency of the oil washing agent reaches 97% and above, and the purpose that the single round of huff-puff can increase the oil recovery rate by 1% is further achieved.

The invention belongs to the field of development of oil field chemicals, and relates to a water-phase tackifying heavy oil emulsifier. The emulsifier comprises an amine oxide type ampholytic surfactant, a betaine type ampholytic surfactant and water. Compared with the existing common heavy oil reservoir emulsification viscosity reducer, the invention has the following beneficial effects: 1, compared with the existing common heavy oil reservoir emulsification viscosity reducer, the components in the water-phase tackifying heavy oil emulsifier disclosed by the invention are economical in price and easy to obtain, and the preparation cost is lower; 2, through the synergistic interaction between the two ampholytic surfactants, the viscosity reduction of heavy oil and the viscosity increase of a water phase can be realized at the same time in the exploitation process, and the oil-water mobility ratio can be effectively improved; 3, emulsification can be realized under the action of micro power.

The present invention provides a supercritical CO2 oil displacement system and an oil displacement method. The supercritical CO2 oil displacement system comprises supercritical CO2 and a base solutiondissolved in the supercritical CO2, and the base solution comprises a polymer, a surfactant, an alkali and water. The supercritical CO2 oil displacement system provided by the invention has a largerswept volume in an oil layer, and the recovery ratio can be greatly improved.

The invention provides a thickener for supercritical carbon dioxide oil displacement as well as a preparation method and application of the thickener. According to the thickener, fluorine-containing acrylate, tertiary amino-containing acrylate and styrene are used as monomers, and the thickener is formed through free radical polymerization. The thickener for supercritical carbon dioxide oil displacement has low cloud point pressure and excellent tackifying performance, and can be used for a supercritical carbon dioxide oil displacement process for further improving the recovery ratio after oilfield polymer flooding.

The invention relates to a method of displacing oil by anionic-cationic composite surfactant and mainly solves the problems that the prior method of displacing oil by surfactant is low in oil displacement efficiency in tertiary oil recovery and an oil displacement system containing inorganic base is harmful to stratums and oil wells, corrosive to equipment and pipelines and difficult for demulsification. According to the technical scheme, crude oil is allowed to contact with oil-displacing agent, and the oil-displacing agent comprises, by weight percent, 0.01-5.0% of anionic-cationic composite surfactant, 0.01-3.0% of polymer, and 92.0-99.98% of injected water. The problems are solved well. The method is applicable to tertiary oil recovery for oil fields.

The invention provides a preparation method and application of a double-braid polymer surfactant containing aryl. The surfactant has a structure as shown in formula (I), wherein x / (x + y + z) * 100% is 0.1%-0.5%, y / (x + y + z) * 100% is 90.8%-93.3%, and z / (x + y + z) * 100% is 6.6%-8.7%, R1 and R2 are respectively and independently selected from hydrogen atom or C1-C20 straight-chain or branched-chain alkyl; n=1-30; the double-braid polymer surfactant provided by the invention has good interfacial activity, and thick oil can be converted into a stable oil-in-water emulsion under stratum low shearing conditions, so that the purpose of viscosity reduction is achieved.