Abstract: The present invention relates to an emulsion, consisting of an oil phase and an aqueous phase and comprising as emulsion components (?1) 15 to 40% by weight of at least one water-immiscible organic solvent as solvent of the oil phase, (?2) 15 to 40% by weight of water as solvent of the aqueous phase, (?3) 10 to 40% by weight of at least one surfactant, (?4) 10 to 40% by weight of an alkoxylated fatty alcohol and (?5) 0 to 25% by weight of at least one other additive, wherein the quantities by weight of the components (?1) to (?5) are each relative to the total weight of the emulsion, and together add up to 100% by weight. The invention further relates to a method for producing an emulsion, to the emulsion which can be obtained from said method, to the use of an emulsion, to a method for cleaning the surfaces of well holes, drilling devices or drillings, to a method for producing a well bore, and to a method for producing an oil or a gas.

Abstract: A method of recovering oil from a heterogeneous reservoir, comprising a plurality of permeable porous blocks of rock whose pores contain oil and which form interfaces with regions between the blocks, e.g. fractures, having a higher permeability than the blocks. Treating the interfaces such that the wettability of the surfaces of the blocks is in a predetermined wettability range, then reducing the permeability in the highly permeable regions, and finally flooding the reservoir by injecting a chase fluid into the reservoir. With the present method, water phase bridges are established between adjacent blocks in the reservoir thus allowing a transmission of injection pressure for viscous displacement from one block to the next across the reservoir. A method for long-time storage of CO2 by using CO2 as chase fluid or foaming gas according to the present method for oil recovery from heterogeneous reservoirs.

Abstract: A method, system, and composition for producing oil from a formation utilizing an oil recovery formulation comprising a surfactant, an ammonia liquid, a polymer, and water are provided.

Abstract: The present invention provides a method of treating a hydrocarbon containing formation comprising (a) providing a hydrocarbon recovery composition to at least a portion of the hydrocarbon containing formation, wherein the composition comprises one or more internal olefin sulfonates having 17 or more carbon atoms, (b) adding water and/or brine from the hydrocarbon formation to the composition, (c) adding a solubilizer which comprises an ethoxylated alcohol wherein the alcohol before ethoxylation had an average molecular weight of at least about 220 and (d) allowing the composition to interact with hydrocarbons in the hydrocarbon containing formation. The solubilizer may comprise less than about 0.1 wt %, preferably from about 0.02 to about 0.05 wt %, of the total composition and it may have from about 5 to about 9 moles of ethylene oxide per mole of alcohol.

Abstract: A process for mineral oil production, in which an aqueous formulation comprising at least one water-soluble, hydrophobically associating copolymer (A) and at least one nonionic and/or anionic surfactant (B) is injected through at least one injection borehole into a mineral oil deposit, and crude oil is withdrawn from the deposit through at least one production borehole, wherein the water-soluble, hydrophobically associating copolymer comprises at least acrylamide or derivatives thereof, a monomer having anionic groups and a monomer which can bring about the association of the copolymer, and aqueous formulation, which is suitable for execution of the process.

Abstract: Process for tertiary mineral oil production in which an aqueous injection fluid comprising at least a water soluble polyacrylamide-(co)polymer dissolved in the aqueous fluid is injected into a mineral oil deposit and the aqueous injection fluid is prepared by mixing a liquid dispersion polymer composition comprising particles of polyacrylamide-(co)polymers dispersed in an organic, hydrophobic liquid with an aqueous fluid. Preferably, the process is carried out on an off-shore production site.

Abstract: Sulfonated betaines amine oxides, and sultaines are made by the reaction of the corresponding unsaturated betaines or sultaines. These are formulated into injection fluids suitable for the recovery of residual oil from subterranean reservoirs. The sulfonated betaines, amine oxides, and sultaines exhibit lower adsorption onto reservoir rock compared to their corresponding unsulfonated betaines, amine oxides, and sultaines. They can be used in applications where their respective amphoteric surfactants are currently used such as personal care, mining, improved oil recovery (IOR), oil field drilling, fracturing, acidizing, foaming, oil field stimulation, and agricultural formulations.

Abstract: The present invention relates to a surfactant mixture comprising at least one surfactant of the general formula (I) R1O—(CH2CH(CH2OR2)O)p-(D)n-(B)m-(A)l-(X)k—Y?1/bMb+??(I) where R1, R2, p, D, n, B, m, A, l, X, k, Y?, b, Mb+ are each as defined in the claims and the description. The invention further relates to processes for mineral oil production by means of Winsor type III microemulsion flooding using a surfactant formulation comprising the surfactant mixture.

Abstract: The present invention relates to a surfactant mixture comprising at least one secondary alkanesulfonate having 14 to 17 carbon atoms of the general formula (I) and at least one anionic surfactant of the general formula (II) where R1, R2, R3, R4, A0, k, X, o, Y, a, b, M are each as defined in the description and the claims. The invention further relates to the use and production thereof, and to aqueous surfactant formulations comprising the surfactant mixture, and to processes for producing mineral oil by means of Winsor type III microemulsion flooding, in which the aqueous surfactant formulation is injected through injection wells into a mineral oil deposit and crude oil is withdrawn through production wells from the deposit.

Abstract: Embodiments of the present disclosure include dispersion compositions having a nonionic surfactant for use in enhanced petroleum recovery, and methods of using the dispersion compositions in petroleum recovery processes. For the various embodiments, the nonionic surfactant of the dispersion composition promotes the formation of a dispersion from carbon dioxide and water.

Abstract: The present invention relates to processes for tertiary mineral oil production with the aid of a surfactant mixture and to the use of a surfactant mixture for tertiary mineral oil production by means of Winsor type III microemulsion flooding, by injecting a surfactant mixture through at least one aqueous injection borehole into a mineral oil deposit, and withdrawing crude oil from the deposit through at least one production borehole, wherein the surfactant mixture, for the purpose of lowering the interfacial tension between oil and water to <0.1 mN/m, comprises at least the following components: (a) one or more polycarboxylate(s) comprising at least 50 mol % of acrylic acid units and/or methacrylic acid units and/or maleic acid units and/or itaconic acid units or salts thereof, and (b) one or more anionic and/or nonionic surfactant(s).

Abstract: A process for enhanced oil recovery includes the steps of providing an alkali metal borohydride; providing an alkali metal bisulfite; combining the alkali metal borohydride and the alkali metal bisulfite along with water to provide an oxygen-scavenger composition; combining the oxygen-scavenger composition and an aqueous composition to provide an oil recovery solution; and introducing the oil recovery solution into an earthen formation at a pressure to provide for enhanced oil recovery.

Abstract: A method and a system for producing petroleum from a formation utilizing a sacrificial agent and a surfactant are provided. The sacrificial agent reduces the amount of surfactant required to enhance oil recovery from a petroleum-bearing formation. The sacrificial agent is provided in a sacrificial agent formulation comprising a sacrificial agent dispersed in a fluid. The sacrificial agent is selected from the group consisting of a compound comprising a single carboxylic acid, a single carboxylic acid derivative, or a single carboxylate salt, or a compound lacking a carboxylic acid group, a carboxylate group, a sulfonic acid group, or a sulfonate group that is a phenol, a sulphonamide, or a thiol, or a compound having a molecular weight of 1000 or less that comprises one or more hydroxyl groups. The sacrificial agent formulation is introduced into a petroleum-bearing formation followed by a surfactant and petroleum is produced therefrom.

Abstract: A method and a system for producing petroleum from a formation utilizing a sacrificial agent and a surfactant are provided. The sacrificial agent reduces the amount of surfactant required to enhance oil recovery from a petroleum-bearing formation. The sacrificial agent is provided in a oil recovery formulation comprising a sacrificial agent and a surfactant dispersed in a fluid. The sacrificial agent is selected from the group consisting of a compound comprising a single carboxylic acid, a single carboxylic acid derivative, or a single carboxylate salt, or a compound lacking a carboxylic acid group, a carboxylate group, a sulfonic acid group, or a sulfonate group that is a pheol, a sulphonamide, or a thiol, or a compound having a molecular weight of 1000 or less that comprises one or more hydroxyl groups. The oil recovery formulation is introduced into a petroleum-bearing formation and petroleum is produced therefrom.

Abstract: Combined injection, production and transportation method for a production well and an injection well of a hydrocarbon-bearing formation and flow line system for surface transportation of a product stream includes introducing a mixture of surfactant, co-surfactant and carrier fluid into each of the wells so that the mixture flows into porous media surrounding the wells; holding the reservoir mixture in the production well in the presence of water for a time sufficient to form water film on surfaces of the porous media surrounding the production well; injecting injection fluid into the injection well while producing from the production well, whereby hydrocarbons flow from the porous media around the injection well toward the production well, introducing an injection mixture of a surfactant and carrier fluid into a desired point in tubing of the production well so that the tubing injection mixture mixes with the production stream forming an emulsion, and producing the emulsion.

Abstract: A system and process are provided for recovering petroleum from a formation. An oil recovery formulation comprising at least 75 mol % dimethyl sulfide that is first contact miscible with a liquid petroleum composition is introduced into a petroleum bearing formation and petroleum and oil recovery formulation are produced from the formation. The produced oil recovery formulation is separated from the produced petroleum, and the produced oil recovery formulation is introduced into the formation.

Abstract: Methods of drilling wellbores, placing proppant packs in subterranean formations, and placing gravel packs in wellbores may involve fluids, optionally foamed fluids, comprising nanoparticle suspension aids. Methods may be advantageously employed in deviated wellbores. Some methods may involve introducing a treatment fluid into an injection wellbore penetrating a subterranean formation, the treatment fluid comprising a base fluid, a foaming agent, a gas, and a nanoparticle suspension aid; and producing hydrocarbons from the subterranean formation via a production wellbore proximal to the injection wellbore.

Abstract: The invention relates to a process for mineral oil extraction by means of Winsor Type III microemulsion flooding, in which an aqueous surfactant formulation comprising at least one ionic surfactant of the general formula R1—O-(D)n-(B)m-(A)l-XY?M+ is injected through injection boreholes into a mineral oil deposit, and crude oil is withdrawn from the deposit through production boreholes. The invention further relates to ionic surfactants of the general formula.

Abstract: A process for mineral oil production especially Winsor type III microemulsion flooding, in which an aqueous surfactant formulation which comprises at least one nonionic surfactant having 11 to 40 ethoxy units and a hydrophobic radical having 8 to 32 carbon atoms and at least one further surfactant differing therefrom is forced through injection wells into a mineral oil deposit and crude oil is removed from the deposit through production wells.

Abstract: A process for mineral oil production, especially Winsor type III microemulsion flooding, in which an aqueous surfactant formulation which comprises at least one nonionic surfactant having 8 to 30 ethoxy units, which has a polydispersity of from 1.01 to 1.12, and at least one further surfactant is forced through injection wells into a mineral oil deposit and crude oil is removed from the deposit through production wells.

Abstract: A composition comprising a fluorinated pyridinium cationic compound of formula (I) wherein Rf is R1(CH2CH2)n—, R1 is a C7 to C20 perfluoroalkyl group interrupted by at least one catenary oxygen atom, each oxygen bonded to two carbon atoms, n is an integer of 1 to 3, and R is H, C1 to C5 linear or branched alkyl, or C1 to C5 linear or branched alkoxy, having surfactant properties for lowering surface tension in an aqueous medium or solvent medium, and for use as a foaming agent.

Abstract: A method for enhancing oil recovery is disclosed. The method includes providing a subsurface reservoir containing hydrocarbons therewithin and a wellbore in fluid communication with the subsurface reservoir. A solution for injection into the reservoir is formed by mixing a composition with at least one non-ionic chemical, at least one polymer, and at least one alkali. The non-ionic chemical can be alcohol alkoxylates such as alkylaryl alkoxy alcohols or alkyl alkoxy alcohols. The solution is solution is clear and aqueous stable when mixed. The solution is injected through the wellbore into the subsurface reservoir.

Abstract: A method of servicing a subterranean formation comprising providing a wellbore penetrating the subterranean formation and having a casing string disposed therein, the casing string comprising a plurality of points of entry, wherein each of the plurality of points of entry provides a route a fluid communication from the casing string to the subterranean formation, introducing a treatment fluid into the subterranean formation via a first flowpath, and diverting the treatment fluid from the first flowpath into the formation to a second flowpath into the formation.

Abstract: A method of recovering oil from a formation that includes the use of surfactants at low concentrations. The surfactant may be an oleophilic surfactant. The method may include conditioning an oil recovery system to inhibit microbes that could consume the oleophilic surfactant. A method that determines the concentration of a surfactant that is sufficient to change the interfacial tension between oil and water in a near well bore area of an injection well in a formation but does not require changing the interfacial tension between oil and water outside the near well bore area.

Abstract: Use of a mixture comprising a surfactant and a cosurfactant in the form of an aqueous solution for flooding underground deposits of hydrocarbons for mobilizing and recovering the hydrocarbons from the underground deposits, the cosurfactant being a substance or a group of substances selected from the following list: an amphiphilic comb polymer having a backbone with two or more side chains attached to the backbone, the side chains differing from one another and/or the side chains differing from the backbone in their amphiphilic character, an amphiphilic polymer having one or more hydrophobic subunits [A2] based on a polyisobutene block, at least 50 mol % of whose polyisobutene macromolecules have terminally arranged double bonds, and one or more hydrophilic subunits [B2], or an amphiphilic polymer having the general structural formula

Abstract: Systems and methods are provided for forecasting performance of polymer flooding of an oil reservoir system. For example, property data of the oil reservoir system and polymer flooding scenario data are received. Numerical simulations are performed to generate values of an effective mobility ratio and response time for the polymer and water flooding. A correlation for the polymer flooding effective mobility ratio is determined and used in a predictive model to generate polymer and water flooding performance data, representative of oil recovery by the polymer and water flooding of the oil reservoir system.

Abstract: The present disclosure relates to enhanced oil recovery methods including the injection of solvent and polymer floods to increase hydrocarbon production from oil bearing underground rock formations. One method includes injecting a solvent slug into the underground formation for a first time period from a first well. The solvent slug solubilizes the oil and generates a mixture of mobilized oil and solvent. An aqueous polymer slug may then be injected into the underground formation for a second time from the first well. The polymer slug may have a viscosity greater than the solvent slug and thereby generates an interface between the solvent slug and the polymer slug. The solvent slug and the mobilized oil are then forced towards a second well using a buoyant hydrodynamic force generated by the aqueous polymer slug. Oil and/or gas may then be produced from the second well.

Abstract: The present invention describes the synthesis and use of cleavable di-functional anionic surfactants for enhanced oil recovery applications and/or the use of sacrificial surfactants.

Abstract: Hydrocarbons are recovered from subterranean formations by waterflooding. The method comprises passing an aqueous displacement fluid via an injection well through a porous and permeable sandstone formation to release oil and recovering said released oil from a production well spaced from said injection well, wherein (a) the sandstone formation comprises at least one mineral having a negative zeta potential under the formation conditions; (b) oil and connate water are present in the pores of the formation; and (c) the fraction of the divalent cation content of the said aqueous displacement fluid to the divalent cation content of said connate water is less than 1.

Abstract: A method of treating a hydrocarbon-containing formation including injecting a scale inhibiting well treating fluid into a well, wherein the well treating fluid includes a self-diverting acid that includes about 1% to 20% by volume of at least one viscoelastic surfactant selected from a family of compounds described by where R3 contains at least 10 carbon atoms, p=1-6, R2 contains 1-6 carbon atoms and R1 contains 1-6 carbon atoms; and up to about 20% by weight scale inhibitor.

Abstract: A process for mineral oil production, in which an aqueous formulation comprising tris(2-hydroxyphenyl)methane of the general formula (I) is injected into a mineral oil deposit through an injection well and the crude oil is withdrawn from the deposit through a production well, where the R1, R2 and R radicals in the formula (I) are each defined as follows: R is independently 1 to 2 hydrocarbyl radicals per phenyl ring, R1 is preferably H or OH, R2 are independently radicals of the general formula (III), —(R5—O—)n—R6—X??(III) where n is a number from 1-50, and where the R5 radicals are R7 groups R6 is a single bond or an alkylene group having 1 to 10 carbon atoms, X is H or an acidic end group, R10 is, for example, C1-C6-hydrocarbyl radical, enables improved mineral oil production.

Abstract: A method for enhancing oil recovery from reservoirs is described. The method includes partially recharging zones of pore space in a reservoir that has been previously waterflooded to extract oil, in order to obtain increased ultimate oil recovery by re-waterflooding the recharged zones. The recharging may be achieved by either reinjection of oil or by change in injection scheme, such as changing an oil producing well to a water injection well. This procedure of recharging with oil followed by waterflooding may be repeated. Application of the present method to increase recovery from reservoirs producing dry (water-free) oil to mature reservoirs which produce at high water-to-oil ratios is anticipated.

Abstract: A process for recovering oil from an oil-bearing formation comprises introducing into said formation an aqueous composition comprising at least one sulfonated derivative of one or more internal olefins, said internal olefins being characterized by having low amounts of tri-substitution on the olefin bond, said sulfonated derivative being obtained by sulfonating a composition comprising internal olefins of the formula: R1R2C?CR3R4 wherein R1, R2, R3 and R4 are the same or different and are hydrogen or straight- or branched-chain, saturated hydrocarbyl groups and the total number of carbon atoms of R1, R2, R3 and R4 is 6 to 44 with the proviso that at least about 96 mole percent of R1 and R3 are straight- or branched-chain, saturated hydrocarbyl groups and at least about 96 mole percent of R2 and R4 are hydrogen.

Abstract: A method is disclosed for manufacturing surfactants for utilization in petroleum industry operations. The method comprises providing a bio-lipid. The bio-lipid can include one or more medium-chain or long-chain fatty acids, such as Lauric acid, Myristic acid, Palmitic acid, Stearic acid, Palmitoleic acid, Oleic acid, Ricinoleic acid, Vaccenic acid, Linoleic acid, Alpha-Linoleic acid, or Gamma-Linolenic acid. Fatty acid alkyl esters are produced by reacting the bio-lipid with a low-molecular weight alcohol. The fatty acid alkyl esters are reduced to a fatty alcohol. The fatty alcohol is dimerized to form a Guerbet alcohol, which is a precursor to producing surfactant for utilization in a petroleum industry operation, such as an enhanced oil recovery process.

Abstract: The invention relates to a method for recovering oil from a fractured reservoir having an oil-wettable matrix and comprising at least one injection well and one production well, both of which arc in communication with the fractures and the matrix, wherein the method comprises the following steps in the following order: a) during a first stage, the injection, by an injection well, of a solution of viscosity-enhancing surfactants, capable of penetrating into the array of fractures, having limited interaction with the matrix, and creating a plug in situ so as to substantially and selectively reduce the perviousness of the fractures and to promote the passage of the solution of step b) into the matrix; b) during a second stage, the injection, by an injection well, of a solution of surfactants, capable of interacting with the matrix in order to make same preferably water-wettable and to extract the oil therefrom, said solution preferably flowing through the matrix; and after a latency period of at least 24 hours,

Abstract: A method for producing oil and/or gas from an underground formation comprising locating a suitable formation with an oil column located above an aquifer; drilling at least one horizontal production well near a top of the oil column; performing primary production to produce a first quantity of fluids from the oil column; drilling at least one horizontal injection well at a location between the horizontal production well and a bottom of the oil column; injecting water mixed with a viscosifier into the horizontal injection well while producing a second quantity of fluids through the horizontal production well from the oil column.

Abstract: A process for the recovery of heavy oil from an underground reservoir, comprising: injecting an oil-in-water nanoemulsion into one or more injection wells; recovering said heavy oil from one or more production wells. Said process is particularly advantageous for enhancing the recovery of heavy oils from underground reservoirs within the range of technologies for tertiary recovery, usually known as “EOR” (Enhanced Oil Recovery”).

Abstract: A multistage process for producing mineral oil from mineral oil deposits by injecting aqueous flooding media into a mineral oil formation through injection boreholes and withdrawing the mineral oil through production boreholes, in which the mineral oil yield is increased by the use of microorganisms in combination with measures for blocking highly permeable zones of the mineral oil formation.

Abstract: A combined injection and production method includes the steps of: establishing a production well and an injection well into a hydrocarbon-bearing formation; introducing a mixture of a surfactant, a co-surfactant and a carrier fluid into each of the production well and the injection well so that the mixture flows into porous media surrounding the production well and the injection well; holding the mixture in the porous media surrounding the production well in the presence of water for a period of time sufficient to form a water film on surfaces of the porous media surrounding the production well; and injecting an injection fluid into the injection well while producing from the production well, whereby hydrocarbons flow from the porous media around the injection well toward the production well.

Abstract: Disclosed herein is a method to control distribution of injected microorganisms, nutrients or other chemical treatment fluids from a single injection well to multiple production wells. The sweep efficiency is improved preventing premature production of fluids from production wells with short breakthrough times. This is a useful technique for treatment of subterranean target sites for practice of Microbial Enhanced Oil Recovery and bioremediation.

Abstract: A process for mineral oil production, in which an aqueous surfactant formulation comprising at least one alkyl polyglucoside is injected into a mineral oil deposit through at least one injection borehole and crude oil is withdrawn from the deposit through at least one production borehole, wherein the formulation does not comprise any alcohols as cosolvents.

Abstract: The invention relates to equipment (10) feeding polymers into a fluid flow which is guided within a pipeline (20) and comprising a control (40) which may be hooked up to a polymer supply line (42), further comprising several feed conduits (70) which are configured between the said control and said pipeline and move the polymers from the control (40) to the pipeline (20). The control (40) of the equipment (10) furthermore includes a valve system (50) designed in a manner that a defined number of feed conduits (70) can be opened or closed. In addition, one static mixer (80, 81) is configured at least in segment(s) in each feed conduit (70). This equipment makes it possible to feed polymers, in particular polymers in aqueous solution and of high molecular weights, at a predetermined pressure and at defined rates into a fluid flow without thereby destroying the molecular chains of said polymers.

Abstract: A two-stage process for mineral oil production from mineral oil deposits with a deposit temperature of more than 70° C. and a salinity of 20 000 ppm to 350 000 ppm, in which an aqueous formulation comprising at least one glucan with a ?-1,3-glycosidically linked main chain, and side groups ?-1,6-glycosidcally bonded thereto and having a weight-average molecular weight Mw of 1.5*106 to 25*106 g/mol, are injected into a mineral oil deposit through at least one injection borehole and crude oil is withdrawn from the deposit through at least one production borehole. The aqueous formulation is prepared in two stages, by first preparing an aqueous concentrate of the glucan, and diluting the concentrate on site with water to the use concentration.

Abstract: The present invention comprises a compound of a compound of Formula 1 wherein Rf is a C2 to C12 perfluoroalkyl optionally interrupted by one to four moieties each independently selected from the group consisting of —CH2—, —O—, —S—, —S(O)—, and —S(O)2—; n is 1 to 6; m is 0 to 2, provided that m is less than or equal to n. X and Y are each independently O or NR, R is hydrogen or C1 to C6 alkyl; R1, and R2 are each independently C1 to C6 alkyl, optionally containing one or more oxygen atoms and may form a ring selected from the group of piperidine, pyrrolidine, and morpholine; and R3 is O?, (CH2)pC(O)O?, (CH2)pCH(OH)(CH2)SO3?, and (CH2)qSO3?; p is 1 to 4; and q is 2 to 4 which is useful as a surfactant.

Abstract: A method of preventing phase separation of a viscoelastic surfactant fluid due to ferric ions during matrix acidizing is described which involves including citric acid and acetic acid in the surfactant/acid fluid formulation.

Abstract: Methods are provided using heated fluids along with combined/drive cyclical injection/production profiles to enhance hydrocarbon recovery from shallow and/or low mobility reservoirs. In certain embodiments, injection and production flow rates to and from the reservoir are varied to beneficially modulate certain pressure drive profiles between a minimum pressure and a maximum pressure. During these drive profile modulations, heated water, solvent, and surfactant are injected into the reservoir. The combination of injected fluids and cyclical pressure drive profiles beneficially enhances hydrocarbon recovery from the reservoir. Other optional variations include using multiple injection and/or production wells. Advantages include accelerated hydrocarbon recovery, higher production efficiencies, and lower costs. These advantages ultimately translate to higher production and/or reduction of total hydrocarbon extraction time. These methods are particularly advantageous when applied to shallow reservoirs (e.g.

Abstract: A method of servicing a wellbore comprising placing a composition comprising a surfactant, brine, an oleaginous fluid, and optionally a co-surfactant in an annular space of the wellbore, wherein the composition forms a microemulsion under low shear conditions.

Abstract: A method for altering flow conditions in a porous media containing hydrocarbons includes the steps of preparing a mixture of a surfactant, a co-surfactant and a carrier fluid; transporting the mixture to the porous media; and holding the mixture in the porous media in the presence of water for a period of time sufficient to form a water film on the surfaces of the porous media.

Abstract: Methods and systems for enhancing oil recovery from a subterranean formation comprising at least a first region and a second region are provided. An exemplary method includes creating an injection stream by adding a salt to a water stream to increase a concentration of an ion and injecting the injection stream into the subterranean formation through a first injection well in the first region of the subterranean formation. Fluid is produced from the subterranean formation and separated to generate an aqueous stream comprising at least a portion of the ion. The salt is added to the aqueous stream to adjust the concentration of the ion in the aqueous stream to a desired level. The aqueous stream is injected into the subterranean formation through a second injection well in the second region of the subterranean formation.

Abstract: Methods and systems for enhanced oil recovery from a subterranean formation are provided. An exemplary includes separating fluid produced from the subterranean formation into a first fluid stream that includes an aqueous stream containing multivalent ions. At least a portion of the multivalent ions in the first fluid are removed to form a second fluid stream and the second fluid stream is injected into the subterranean formation. The first fluid stream and the second fluid stream have substantially the same interfacial tension with a hydrocarbon and substantially the same kinematic viscosity, and the second fluid stream has a total concentration of ions greater than about 100,000 ppm.