452results about How to "Improve oil displacement efficiency" patented technology

The invention provides a foam profile control agent applicable to oil field in-depth profile control. The foam profile control agent provided in the invention comprises a polymer cross-linking solution and gas; under formation pressure, a volume ratio of the gas to the polymer cross-linking solution is 0.2: 1 to 1: 1; and the polymer cross-linking solution of the foam profile control agent comprises, by weight, 0.3 to 1.2 wt% of a surfactant, 0.01 to 0.8 wt% of a polymer, 0.001 to 0.2 wt% of a cross-linking agent, 0.001 to 0.1 wt% of a stabilizing agent and 0.05 to 1.5 wt% of inorganic salt, with the balance being water. The foam profile control agent has an effect on delaying cross-linking, can effectively plug a high-permeability zone, can reduce oil-water interfacial tension and has the effects of enlarging swept volume and improving oil displacement efficiency.

The invention discloses a foam profile control system suitable for advanced profile control of an oilfield. A liquid of the system is prepared from a first surfactant, a second surfactant, granules, a foam stabilizer, a polymer, a crosslinking agent, a stabilizer, an adjustor, inorganic salt, a control agent and water. The foam profile control system has three characteristics of foam, gels and granules at the same time, and has a strong deep sealing capacity to a high-permeability oil layer, namely, has an effect on expanding the swept volume. The system further can reduce the oil-water interface tension, and mainly exerts a gel performance at a low-permeability layer and a foam property at a high-permeability layer, that is, the system has the effects on improving the oil dispelling efficiency and selectively plugging water. When the system is used, as gases exist, the use level of the foam profile control system is reduced, and the foam profile control system has the characteristics of temperature resistance and salt resistance at the same time.

The invention provides a fracturing method for supplementing stratum energy of dense oil reservoir. The method includes the steps that in combination with characteristics of the dense oil reservoir, characteristics of non-darcy seepage are considered, and CMG oil reservoir value simulation software is utilized to simulate and calculate a discharge area controlled by a single fracture under the modes of subdivision cutting and a complex fracture net with the starting pressure gradient considered; in combination with a fracture spacing chemical interference theory, the horizontal well improvement segment spacing improved by dense oil reservoir size fracturing, cluster spacing and perforating parameters are optimized; the dense oil reservoir transformation parameter is determined through a non-darcy seepage equation and the CMG oil reservoir value simulation software; the ram material composition of fracturing liquid is determined according to the wettability and sensitivity of the reservoir; the fracturing liquid and a propping agent are poured, the flow velocity of the eyelet of a single liquid suction and injection hole of the fracturing liquid is 0.25 m<3> / min-0.4 m<3> / min, and the pouring intensity is 10 m<3> / min-15 m<3> / min; the well closing time is determined through the CMG oil reservoir value simulation software, a well is closed according to the determined well closing time, and the fracturing method integrates pressing, pouring, driving and exploiting.

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 deep profile control method for a fractured oil reservoir. By the method, the recovery ratio of crude oil can be increased. Four sections of plugs are provided for plugging different types of fluid-channeling channels, wherein in the first section of plug, a high-strength solidification system is used for plugging fracture; in the second section of plug, inorganic gel is used for plugging microfracture or large pores; in the third section of plug, a water drive flow direction changing agent and weak gel are used for further filling the fracture and the pores so as to displace residual oil in the pores; and in the fourth section of plug: a strong gel YQY plugging agent is used for plugging the fracture near the wellbore. By the method, the problem that the oil well is flooded by water caused by the fracture of the fractured oil reservoir water injection well can be effectively solved; the water absorption condition of a storage layer is changed; the utilization ratio of the injected water is increased; the swept volume is enlarged; and the oil displacement efficiency is improved finally.

The invention discloses a viscosity-reducing oil displacement agent for heavy oil reservoirs, wherein the components comprise, by weight, 20-60% of an emulsifier, 1-5% of an ester-based compound, 0.2-2% of a wetting agent, and the balance of water. The invention further discloses a viscosity-reducing oil displacement agent-polymer system for heavy oil reservoirs, wherein the viscosity-reducing oil displacement agent-polymer system comprises 0.1-1% of the oil displacement agent, 0.05-0.3% of a polymer and the balance of water, and the polymer is polyacrylamide with a molecular weight of 8000000-20000000. According to the present invention, the viscosity-reducing oil displacement agent and the viscosity-reducing oil displacement agent-polymer system can provide good effects of viscosity reducing and emulsifying for heavy oil, can substantially reduce the viscous force of heavy oil in rock pores, can provide good profile control and water blocking effect, can effectively improve oil displacement efficiency, can improve heavy oil recovery, and are suitable for heavy oil reservoirs with a stratum viscosity of more than 200 mPa.s.

The invention discloses a hydraulic power pulse oil displacement experimental facility and an experimental method thereof. The experimental facility comprises a core clamping device, an annular pressure supply device, a hydraulic power pulse wave generating device, a water storage tank and an oil storage tank which are connected with the liquid inlet of the core clamping device by virtue of a water pipeline and an oil pipeline as well as a liquid container which is connected with the liquid outlet of the core clamping device; wherein the water pipeline and the oil pipeline are all provided with an intermediate container, a pumping device used for generating high pressure liquid flow and an energy storage tank. The experimental method includes the following steps: firstly, oil displacementexperiment is carried out under the condition that no hydraulic power pulse is added; secondly, oil displacement experiment is carried out while frequency and amplitude hydraulic power pulse wave of core are replaced, and meanwhile hydraulic power pulse auxiliary chemical oil displacement experiment is completed; thirdly, data processing is carried out. The invention has reasonable design, mounting convenience, simple operation and good simulation effect, can improve efficiency of oil displacement by water and crude oil recovery ratio, and experiment of hydraulic pulse wave oil displacement and hydraulic pulse wave auxiliary reservoir core oil displacement by water can be realized.

The invention discloses a supercritical multisource multielement thermal fluid injection-production system and injection-production method. The system comprises a supercritical multisource multielement thermal fluid generating system and an oil tube. The oil tube is arranged in an exploiting shaft; the supercritical multisource multielement thermal fluid generating system comprises a supercritical gasification reactor and a supercritical mixed combustion reactor; in the presence of supercritical water, a gasification reaction is performed on fuel slurry in the supercritical gasification reactor, and the gasification product of the reaction and oxygen-containing gas dissolved in the supercritical water combust in the supercritical mixed combustion reactor to form a supercritical multisource multielement thermal fluid containing supercritical water and carbon dioxide; the supercritical mixed combustion reactor is connected to the oil tube. The supercritical multisource multielement thermal fluid injection-production system provided by the invention has the effects that thermal efficiency is high, the viscosity of thickened oil is reduced, the flowability of the thickened oil is improved and the recovery efficiency is increased.

The invention relates to a technique combining the chemical huff and puff stimulation and the reversed plugging control. The technique adopts slug-type injection mode, including active agent slug, water plugging profile modification agent slug an displacement fluid slug, and includes the following steps: (1) firstly, injecting the active agent into the oil production layer, (2) injecting the water plugging profile modification agent 0-20 hours later, (3) then using excessive displacement fluid to lift all chemical agents to a place which is more than 3m away from well bore, and then using water to displace the excessive displacement fluid to the stratum and finally closing the well for 1 to 2 days for condensation. The purpose of the technique is to combine the huff and puff of the active agent with high oil-washing efficiency and low interfacial tension and the reversed profile control and flooding of the oil well, thus not only increasing the conformance factor of the injection of the water but also improving the oil displacement efficiency and extending the life circle.

The invention relates to a flooding system used for improving the recovery factor after polymer flooding and a preparation method thereof, which belongs to the technical field of enhanced recovery of oil fields. A surfactant with unlike charges and a polymer react with each other to produce a high-activity compound; and the high-activity compound is mixed with a non-ionic surfactant to produce the novel flooding system. The novel flooding system solves the problems of the poor temperature resistance and the inorganic high valence cation resistance of the prior flooding system. The novel flooding system has the advantages of high viscocity, ultra-low interfacial tension, low feeding quantity and so on. The system has wide application prospects in oil fields to apply the technology for improving the oil recovery factor.

The invention provides a foaming agent for plugging gas channeling in displacement of reservoir oil by using CO2. The foaming agent is composed of the following components in percentage by weight: 0.12%-0.30% of anionic surfactant, 0.06%-0.15% of imidazoline-derived ampholytic surfactant, 0.12%-0.30% of lycine-derived ampholytic surfactant, 0.02%-0.04% of foam stabilizer and the balance of water. The foaming agent for plugging gas channeling in displacement of reservoir oil by using CO2 is characterized in that the anionic surfactant, the imidazoline-derived ampholytic surfactant, the lycine-derived ampholytic surfactant and the foam stabilizer are combined so that the obtained foaming agent is capable of forming stable foam with the CO2, and thus is strong in foaming capacity and high in stability; the foaming agent has high plugging selectivity and can be used for plugging CO2 channeling in the displacement of reservoir oil by using CO2, and therefore, the plugging effects of plugging water rather than oil and plugging large rather than small can be achieved, and the oil recovery factor and the effect of the displacement of reservoir oil by using CO2 can be improved.

The invention provides a composition of a surfactant oil displacement system for anionic and nonionic oil displacement. The composition consists of 18% C18 sodium alkyl benzene sulfonate, C16 fatty acid, 25% C2 alkanolamide, 7% C8 alkylphenol polyoxyethylene ether phosphate, 17% ethanol, 3% octanol, 30% water; the alkyl is a hydrocarbyl group with linear chain, branched chain and ring structures in a calibrated carbon atom range, and also can be substituted by one or more halogens, alkyls or alkoxys; the sodium sulfonates are formed by sulfonating different alkanes or arenes by SO3 or chlorosulfonic acid in chloroalkane environment and then neutralizing the sulfonate and sodium hydroxide; and the esterification derivatives are sulfates or phosphates. The formulation has highoil displacement efficiency, strong oil deposit adaptability and good popularization prospect.

The invention relates to a binary alkali-free complex composition for flooding, suitable for high-temperature and high-salinity reservoir, and application of the composition. The binary alkali-free complex composition for flooding is composed of the following components measured by total weight of the binary alkali-free complex composition for flooding: 0.05-0.3% of complex surfactants, 0.1-0.25% of polymers and the balance of water; wherein the compound surfactants are composed of two kinds of hydroxysulfobetaine with different structures and a mass ratio of 9: 1-4: 6. The invention further provides the application of the binary alkali-free complex composition for flooding in tertiary oil recovery. According to the binary alkali-free complex flooding composition provided by the invention, interface performance exceeds the performance of the composition simply utilizing erucamide hydroxysulfobetaine as surfactants to achieve ultralow interfacial tension, and at the same time, the interfacial tension of the composition in a long term can be kept at an ultralow state; and oil recovery cost also can be reduced.

The invention provides an amphiphilic Janus nano particle and a preparation method and application thereof. The preparation method comprises the following steps: dispersing silicon dioxide nanoparticles in water to obtain a dispersion liquid, mixing the dispersion liquid and liquid paraffin, heating and stirring in a water bath to form a Pickering emulsion, cooling to obtain small wax balls, adding a silane coupling agent into the small wax balls for modification to obtain modified small wax balls, mixing the modified small wax balls, an amidation catalyst and C12-C18 saturated fatty acid, andcarrying out an amidation reaction process to obtain organic hydrophobic chain grafted oil-water amphiphilic nanoparticles, and removing paraffin in the organic hydrophobic chain grafted oil-water amphiphilic nanoparticles to obtain the amphiphilic Janus nano particles. When the surfactant is used as an oil-displacing agent, oil-water interfacial tension can be effectively reduced at low concentration, rock wettability is changed, oil-displacing efficiency of nanofluid is remarkably improved, economic cost is reduced, and the surfactant has a wide application prospect.

The invention discloses a three-phase self-foaming water-plugging agent, and belongs to the field of petroleum chemistry. The provided water-plugging agent comprises the following components: solid particles, a foaming agent, a foam stabilizing agent, a crosslinking agent, a delaying agent, and a gas producing agent. Compared with the prior art, the provided water-plugging agent has the advantages of high foam quality and good stability, the gel crosslinking and gas production can be achieved at the same time, the water-plugging agent can tolerate high temperature, has a strong residue blocking performance and a long water-plugging period, and can achieve efficient plugging and depth profile control. Moreover, the preparation technology of the provided water-plugging agent is simple, the injection cost is low, and the water-plugging agent is safe and reliable, thus has a good market prospect and high economic value, and is especially suitable for the development of high temperature heavy oil steam stimulation wells.

The invention relates to a binary compound oil-flooding composition and application thereof in tertiary oil recovery. According to the total weight of the binary compound oil-flooding composition, the binary compound oil-flooding composition comprises the following components: 0.05 to 0.3% of compound surfactant, 0.1 to 0.25% of polymer and the balance of water, wherein the compound surfactant comprises two kinds of hydroxysulfobetaine with different structures in a mass ratio of 9 : 1 to 3 : 7. The invention further provides the application of the binary compound oil-flooding composition in the tertiary oil recovery. The binary compound oil-flooding composition not only has good interface performance and very good emulsifying property and has a good oil-flooding effect.

The invention relates to an oil-displacing agent and an oil-displacing method for enhancing the recovery ratio of high-temperature, high-salinity and high-hardness reservoir crude oil. The oil-displacing agent is composed of the following components in percentage by mass: A, 0.05-0.07% of an amine oxide type amphoteric surfactant; B, 0.15-0.20% of alkylphenol ethoxylate carboxylate; and C, the balance of water. The oil-displacing method disclosed by the invention is implemented through injecting the oil-displacing agent into a natural core subjected to oil-displacing under the conditions that the oil reservoir temperature is 100-120 DEG C, the total salinity of formation water is (10-15)*10<4> mg / L, and the amount of calcium-magnesium divalent metal ions is 7000-10000 mg / L, so that residual oil is in contact with the oil-displacing agent, and then the residual oil is fully displaced. The oil-displacing agent provided by the invention reaches the magnitude order of 10<-3> mN / m under the condition of high-temperature, high-salinity and high-hardness salt reservoirs, and the interfacial tension still can be maintained in an ultra-low interfacial tension state after the oil-displacing agent is aged for a long time under the condition of oil reservoirs, therefore, the oil-displacing agent is applied to the tertiary oil recovery production of oil fields.

The invention discloses a method for multi-section equal-fluidity energy-assembled parallel synchronous oil driving in non-uniform oil layer. First, according to the water adsorption ability, dividing the non-uniform oil layer into several sections; then selecting the fluidity of oil driving agent and keep the fluidity of each section same; uses the formula that the fluidity=oil layer filter rate / fluid viscidity to calculate the fluid viscidity of needed oil driving agent; and selecting polymers to attain the fluid in said viscidity; the sub sections in different viscidities are connected to the integrated one; at last, from high to low viscidity, filling sub sections into oil layer. The invention changes the integrated oil driving into separated oil driving, with less driving resistance; the energy-assembled section has high part pressure, and high driving pressure difference. And it can reduce ineffective water cycle, improve efficiency and reduce the consumption of driving agent.

The invention provides an amphipathic polymerizable monomer with a structure shown as a formula (I), and further provides a preparation method for the amphipathic polymerizable monomer and an amphipathic tackifying copolymer. The amphipathic polymerizable monomer has high amphipathy, and has a self-solubilizing function when used for preparing a polymer; a copolymer with an amphipathic micro block structure and high solubility can be obtained without adding any surfactant; the amphipathic polymerizable monomer belongs to a derivative of acrylamide, and is easy to copolymerize with an acrylamide monomer; and two hydrogen atoms on acidamide N are substituted, so that the hydrolytic resistance of the acidamide N and the copolymer are enhanced, and the high-temperature stability of the copolymer is enhanced. The amphipathic tackifying copolymer has a simple preparation process, and can be prepared without adding a large quantity of surfactants, and the production cost is greatly lowered.

The invention provides a method for developing a heavy oil reservoir of a horizontal well by combining staged volume fracturing and fracturing filling. According to the method, firstly, a steam injection well is deployed at the bottom of the oil reservoir; a production well is deployed at the middle upper part of the oil reservoir; then, the volume fracturing or fracturing filling operation is performed according to the porosity degree and seepage rate distribution condition of the two horizontal wells; then, the two wells form heat communication in a steam throughput mode; next, the two wells transfer to continuous steam injection production; and the production is stopped when the oil-steam ratio is lowered to 0.1. According to the invention, a fracture net system is formed in a compact region by the volume fracturing, so that the seepage capability of the oil reservoir is improved; the fracturing filling process is used in a high-porosity and high-permeability region for performing compaction so as to reduce a formation sand production phenomenon; the seepage mode of a low-permeability region oil reservoir is converted from the single seepage to the sewage and fracture laminar flow; meanwhile, a high-permeability region is filled with small-grain-size sand for filling loose reservoir sandstone particle pores, so that the permeability near the production well is reduced,the oil reservoir anisotropy is reduced and the whole oil reservoir can be uniformly used and developed.

The invention provides a gel composition and a nitrogen-foamed gel composite temporary plugging agent containing the same. The gel composition comprises the following components in percentage by mass: 1.0% of partially hydrolyzed polyacrylamide, 1.5% of formaldehyde, 0.5% of hydroquinone and the balance of water. The nitrogen-foamed gel composite temporary plugging agent comprises nitrogen and foamed gel, wherein the foamed gel is a mixture of the gel composition and a high-temperature-resistant foaming agent; and the volume ratio of the nitrogen to the foamed gel is (40-60):1. The invention also provides a coupled internal / external swirl foam generator which can be used as a facility for preparing the nitrogen-foamed gel composite temporary plugging agent. The invention also provides a method for inhibiting high-throughput-frequency well steam channeling interference of thick oil, which has the characteristics of small formation damage, strong selectivity for measures and the like and has the effect of gas energization.

The invention relates to a ternary complex composition for flooding, suitable for high-temperature and high-salinity reservoir, and application of the composition. The ternary complex composition for flooding is composed of the following components measured by total weight of the ternary complex composition for flooding: 0.05-0.3% of complex surfactants, 0.1-0.25% of polymers, 0.05-2.0% of alkaline matters and the balance of water; wherein the complex surfactants are composed of two kinds of hydroxysulfobetaine with different structures and a mass ratio of 9: 1-4: 6. The invention further provides the application of the ternary complex composition for flooding in tertiary oil recovery. The ternary complex flooding composition of the complex surfactants provided by the invention is featured with high flooding efficiency and low cost of oleamide hydroxysulfobetaine, and is capable of reducing flooding cost.

The invention provides a microbacterium oxydans for degrading a polycyclic aromatic hydrocarbon and the application thereof. Particularly, the invention provides a microbacterium oxydans Ji2 strain with a preservation number of CGMCC No.9072 and the application effect of the microbacterium oxydans in emulsifying and degrading crude oil and the polycyclic aromatic hydrocarbon and performing indoor physical simulation oil displacement. According to the microbacterium oxydans strain, the crude oil can be emulsified and degraded under aerobic and anaerobic conditions by taking the crude oil or the polycyclic aromatic hydrocarbon as the only carbon source and energy source, the degradation rate of the degraded polycyclic aromatic hydrocarbon, such as naphthalene is up to 100 percent, and analysis on the degraded crude oil shows that aromatic hydrocarbon and colloid, which are the components of the crude oil, are mainly degraded. The stain can be used for degrading the polycyclic aromatic hydrocarbon in an environment by the performance of the stain, and can also be applied to microbial enhanced oil recovery, and the oil recovery is improved.

The embodiment of the invention discloses a longitudinally superposed developing three-strata oil reservoir well pattern and a deployment method of the longitudinally superposed developing three-strata oil reservoir well pattern. To the longitudinally superposed developing three-strata oil reservoir, the well spacing of a basic well pattern is 2*(square root of 2)*L; after being encrypted once, the well spacing of a middle transitional well pattern is 2L; after being encrypted twice, two superposed inverted nine-spot well patterns with well spacing of 2L are formed; after being encrypted for three times, two superposed inverted nine-spot well patterns with well spacing of 2L and one superposed inverted nine-spot well pattern with well spacing of (square root of 2)*L are formed; and after pairwise alternatively development, the well spacing of the plane well pattern of each strata has a rational well spacing of L; the evolution process of the well spacing is as follows: 2*(square root of 2)* L to 2L to (square root of 2)*L to L; the middle process of well patterns conversion with a well spacing of 2L and (square root of 2)*L is added; at the same drilling speed, well placement uniformity coefficient and reserve control speed are increased; the well spacing is encrypted in the alternation of well patterns; each well pattern can realize order development to each longitudinal strata; the utilization ratio of the well patterns is improved; meanwhile, the oil reservoir is uniformly used, so that the method is in favor of increasing accumulated oil production of an oil field and improving the recovery ratio; and interlayer interference generated by commingled extracting oil in multiple oil layers of longitudinal series of strata is avoided.

The invention relates to a method for improving the oil-water displacement recovery ratio of a low-permeable oil reservoir, which comprises the following steps of: preparing a mixed aqueous solution containing 400-4000mg / L of surfactant and 200-2000mg / L of foam stabilizer from the surfactant, the foam stabilizer and water; and mixing the mixed aqueous solution and a gas according to a volume ratio of the solution to the gas of 1: (0.1-2), and injecting into the oil reservoir through a water injection well, wherein the injection time is 90-120 days. The surfactant is selected from one or two of branched sodium alkybenzenesulfonate, alkyl polyoxyethylene ether sodium sulfate, alkyl polyoxyethylene ether sodium carboxylate, fatty alcohol ether sodium sulfate and cocoamido propyl hydroxy sulfobetaine; the foam stabilizer is sodium carboxymethylcellulose; and the gas is air. According to the invention, after the water content of the extracted solution reaches 60 percent, the oil displacement efficiency is improved by 20 percent compared with waterflooding, and the water content is reduced by 13-27 percent.

The invention provides a heat resistance and salt tolerance polymer for oil displacement and a preparation method thereof. A heat resistance and salt tolerance functional monomer is introduced into an acrylamide copolymer, so that the heat resistance and salt tolerance of the polyacrylamide are improved; due to the introduction of the functional monomer, the stability of the polymer can be improved in long-term use, the entanglement capacity of the molecular chain of the polymer is maintained, the viscoelasticity of the polymer is improved, and the oil displacement efficiency is improved.

The invention discloses a fracturing oil displacement method for improving the economic efficiency of thin-difference reservoir recovery of an old oil field. The method is based on oil reservoir evaluation and residual oil description. A fracturing measure process scheme is designed in a targeted manner, and a fine control fracturing technology is adopted the fracturing oil-displacing agent is injected into the stratum at high strength within a short time, the fracturing oil-displacing agent with good fracturing performance and a good displacing and washing effect is used for pressing open thestratum to generate cracks, meanwhile, a large amount of oil permeates into the stratum, the stratum energy is increased, stratum remaining oil can be efficiently displaced and washed, and then the recovery ratio of a thin-difference oil layer is greatly increased. According to the method, reservoir transformation, energy supplementing and chemical flooding washing are combined into a whole, therecovery efficiency can be comprehensively improved, construction parameters and fracturing oil displacement agent performance in fracturing can be reasonably optimized, and fracturing-injection-flooding washing integrated novel technology for improving the recovery ratio, which realizes the organic combination of a reservoir transformation technology and oil reservoir development integration andimproves the economic efficiency of thin-difference reservoir recovery of an old oil field.

The invention relates to an oil displacement composition used for low permeability oil reservoirs, and a preparation method thereof, and mainly solves the problems of easy stratum obstruction and difficult injection in the low permeability oil reservoir oil displacement process of present composite flooding polymers. The oil displacement composition contains a long carbon chain betaine surfactant and an inorganic salt, wherein the long carbon chain betaine surfactant is anyone selected from long chain carboxylic acid betaine and sulfonic acid betaine, the carbon chain is a C14-C40 alkyl or alkenyl group, the inorganic salt is anyone of or a composition of CaCl2, MgCl2, NaCl and NaHCO3, and a mass ratio of the long carbon chain betaine surfactant to the inorganic salt is 1:(1-100). The oil displacement composition has the advantages of formation of oil-water ultralow interface tension, decompression and augmented injection, and simple system, well solves the problems, and can be used in the intensified oil production process of the low permeability oil reservoirs.

A functional polymeric surfactant reinforced combination flooding composition contains the following ingredients, by weight, 0.05-0.5% of polymer, 0.03-0.5% of a sulfonate surfactant, 0.01-0.3% of a functional polymeric surfactant, 0.0-0.3% of a nonionic surfactant, 0.2-1.5% of alkali and the balance water. The functional polymeric surfactant is a copolymer of an acrylamide monomer and / or a hydrophilic monomer and / or a functional monomer. According to the reinforced combination flooding composition, multiple oil-displacement mechanisms are combined. In a low-concentration system, the purpose that a three-compounds combination flooding has higher crude oil recovery can be achieved. After polymer flooding, oil reservoir also has a certain effect of raising crude oil recovery.

The invention relates to an active water oil displacement method used for low permeability reservoirs, in particular to a strengthened oil displacement method, and mainly solves the problem of low efficiency of oil displacement of the low permeability reservoirs in the prior art. According to the oil displacement method, a positive-negative system surfactant containing a 0.01-1.0wt% anionic-nonionic surfactant and a cationic surfactant in a molar ratio of 1:0.01-0.99 is injected into a water solution to form active water, dehydrated crude is enabled to be in contact with the active water under the condition of injected water at the oil displacement temperature of 40-100 DEG C with total mineralization (total dissolved solid) TDS more than 200mg / L, and crude in the core is displaced sufficiently. The problem is well solved, and the strengthened oil displacement method can be applied to tertiary recovery production of the low permeability reservoirs.