HK1136842A - Functional polymer for enhanced oil recovery - Google Patents

Description

Functional polymer capable of improving petroleum recovery ratio

RELATED APPLICATIONS

This patent application claims priority from united states provisional patent application 60/853,468 filed on 23/10/2006. The entire contents of this provisional application, including the drawings, are incorporated in the present patent application.

Technical Field

The present invention relates to the field of petroleum production. In particular, the present invention relates to the use of functional surface active polymers to enhance oil recovery.

Background

The recovery of hydrocarbons (e.g., oil) from hydrocarbon (e.g., petroleum) containing reservoirs relies primarily on the natural energy in the reservoir to drive it as a primary energy source to the production well. However, this method generally recovers only a small portion of the original crude oil geological reserves (OOIP). Therefore, in order to enhance the recovery of underground petroleum, a number of secondary recovery techniques are put to use.

The achievement of oil recovery displacement depends on two important factors: volume sweep efficiency and microscopic oil displacement efficiency. The method of Enhanced Oil Recovery (EOR) is typically to inject a fluid or class of fluids into a reservoir. The injected fluid and the injection method supplement the natural energy in the reservoir, together displacing the crude oil to the production well. In addition, the injected fluid interacts with the reservoir rock and the oil system, creating conditions conducive to oil recovery. Mobility control methods and chemical methods are two common methods for enhanced oil recovery.

A widely used method of fluidity control is polymer flooding. Typically, a polymer solution is designed to provide a favorable mobility rate between the injected polymer solution and the oil/water bank being displaced in front of the polymer. The objective is to create a uniform volume sweep in both the longitudinal and upward direction of the reservoir to prevent water breakthrough while preventing water from reaching the production well through the shortest path. Since the 60's of the 20 th century, many polymer projects were put into practice. However, the mobility control method does not itself use microscopic oil displacement efficiency, and the recovery rate of this method is low, limiting the increase in oil recovery, which is typically less than 10% of the original crude oil geological reserves. The statistical data of all the state of the art polymer items were analyzed by Manning ET al, with a median oil recovery of 2.91% OOIP (1983, Report DOE/ET/10327-19). Schurz et al concluded 99 projects between 1980 and 1989 and showed a median enhanced oil recovery of between 3.7% and 4.8% (1989, NMT 890029, New Mexico Tech Centennal Symposium). Gogarty et al discuss that many of the concerns of polymer flooding enhanced oil recovery are a result of accelerated oil production before the economics reach limits (1976, SPE 1566-A, pp.149-160).

Chemical methods employ the injection of a specific liquid chemical whose phase properties reduce the interfacial tension (IFT) between the displacement fluid and the oil, thereby displacing the oil efficiently. The surfactant/polymer approach has proven to have potential for enhanced oil recovery applications. The method comprises injecting a micelle solution as surfactant main slug, and then injecting fluidity buffer solution, usually a solution containing gelatinThere is a gradient concentration of polymer solution. The surfactant plug is gradually diluted in the polymer as the injection solution increases. Recovery is primarily by using an ultra low IFT between the displacement fluid and the oil being displaced. Green et al specifically note that the interfacial tension of the displacement fluid must be reduced to an ultra-low level, perhaps 10, before the waterflood residual oil saturation is sharply reduced^-3Dynes/cm (1998, ISBN 1-55563) -077-4, SPE Textbook Series Vol.6, pp.35). But this is also disadvantageous. To achieve ultra-low IFT, chemical solutions require the addition of surfactants, co-surfactants, and sometimes oils, electrolytes, and bases. This makes chemical solutions complex and expensive, and may also require additional chromatographic separations in EOR operations.

Since Strauss et al first disclosed the concept of polymeric soaps in 1951, there was a large number of literature publications on the neutralization of ordered assemblies of amphiphilic molecules and the polymerization of ordered assemblies of amphiphilic molecules. To some extent, the polymeric surfactant and the low molecular weight surfactant have the same function. However, the high molecular weight and complex structure of polymeric surfactants give them some unique characteristics. Such as the formation of micelles of single molecules in dilute solution and different shapes of micelles at different concentrations, etc. Its use as an emulsion stabilizer in submicron colloid systems has also been disclosed. The great advantage of having macromolecular chains on the surface of colloidal particles is that the polymer surfactants are more and more noticed. The combination of its rheological characteristics (such as thickening behavior) and unique phase properties has potential for wide application in superabsorbent, emulsion paints, hydraulics, flocculation, protein separation, controlled drug release, and biological and medical devices. But only a few have explored the use of polymeric surfactants to enhance oil recovery.

Chemical method theory generally holds that microscopic oil displacement efficiency largely determines the saturation of reservoir rock after residual oil displacement, which is one of the main criteria for assessing the success of a chemical EOR method. Capillary pressure and viscous force determine phase capture and movement of fluid in the porous medium, and further determine microscopic oil displacement efficiency.Green et al investigated the number of capillaries N_ca＝(vμ_w)/δ_owWherein N is_caCapillary number, v pore velocity, μ_wTo displace phase viscosity, δ_owIFT for the displacing phase and the displaced phase (1998, ISBN 1-55563) 077-4, SPE Textbook Series Vol.6, pp.22). Unless delta_owTo 10^-3It is widely accepted that ultra low levels of dynes/cm do not allow for significant reductions in residual oil saturation. Thus, current developments in polymeric surfactants have focused on selecting polymeric surfactants or preparing solutions containing polymeric surfactants, and co-surfactants or other additives that result in lower or ultra-low IFT values between the oil and water phases.

For example, in the early 80's of the 20 th century, Chen et al (1981, U.S. Pat. No.4,284,517, 1982, U.S. Pat. No.4,317,893) disclosed a method for recovering oil by infiltration into a subterranean petroleum reservoir using an interval injection and production system. The method introduces an aqueous solution containing a polymeric surfactant into the reservoir via an injection system, displacing oil into the production system. Chen et al specifically emphasize that the oil-water interfacial tension should be less than 0.1 dyne/cm (e.g., a more desirable oil-water IFT of 0.005 dyne/cm or less) to achieve the best micro-flooding efficiency.

Cao et al (2002, European Polymer Journal, 38(7), pp.1457-1463) have discovered a new family of polymeric surfactants that have enhanced petroleum recovery potential. The novel polymeric surfactants are based on carboxymethyl cellulose and alkyl polyoxyethylene ether acrylates. The IFT characteristics of the polymeric surfactant changed very little upon addition of NaCl. The formed micelle shrinks and becomes smaller in volume. It enables a slight drop in IFT due to the presence of a small amount of free chains in the alcoholic solution. Upon addition of base, the IFT of the polymeric surfactant in aqueous solution was reduced to 10^-2Dyne/cm or less.

While hydrophilic modified water-soluble copolymers have received considerable attention recently, attempts to enhance oil recovery using polymeric surfactants have been primarily directed to producing effective, stable viscosities to improve their sweep efficiency as mobility controllers, under the influence of conventional theory of chemical methods utilizing ultra-low IFT displacement fluids. McCormick et al have conducted a thorough and intensive laboratory study with the ultimate goal of developing a "smart" multifunctional polymer. The polymer can make real-time reaction, stimulate and greatly improve the sweep efficiency in an EOR method (2004, 2005, DOE Report, Awardmarer DE-FC26-03NT 15407). McCormick et al have only studied the advances in sweep microscopic oil displacement efficiency and phase behavior compared to polymers in polymeric surfactants, but have not disclosed the use of polymeric surfactants with oil-water interfacial tension values greater than 0.1 dynes/cm in EOR.

Contrary to conventional theory, the present invention unexpectedly discovered that polymeric surfactants having a moderate oil-water IFT, such as not less than about 0.1 dynes/cm (e.g., preferably between about 0.1 and about 15 dynes/cm), have both volumetric sweep efficiency and microscopic displacement efficiency, and can be used to recover hydrocarbons in subterranean formations.

Brief introduction to the invention

The present invention relates to a method for recovering hydrocarbons from a hydrocarbon-bearing subterranean reservoir or formation by injecting a displacement solution containing a functional polymeric surfactant into the reservoir or formation. The functional polymeric surfactant has an oil-water IFT value of not less than about 0.1 dynes/cm, preferably from about 0.1 to about 15 dynes/cm.

The present invention also relates to functional polymeric surfactants having a partially hydrolyzed polyarylamine backbone and repeating monomer units of the formula wherein the FPS has an oil-water IFT value of not less than about 0.1 dynes/cm, preferably about 0.1 to about 15 dynes/cm,

the repeating monomer unit formula is as follows:

(chemical formula (1))

R_f＝-NH₂，-ONa，-OR_L，-NHR_L，-R_LSO₃Na，-(EO)_a(PO)_bR_LQuaternary ammonium surface active group, diammonium salt Gemini surface active group, -R_LSH and the like, PO represents-CH₂-CH(CH₃) -O-and EO represents-CH₂-CH₂-O-wherein R_LIs a hydrophobic group (e.g., alkyl, phenyl, or derivatives thereof), and a + b is an integer from 6 to 30.

The present invention also relates to a functional polymeric surfactant comprising a first repeating monomeric unit and a second repeating monomeric unit represented by the following formula, wherein the FPS has an oil-water IFT value of not less than about 0.1 dyne/cm, preferably from about 0.1 to about 15 dyne/cm, wherein the formula is as follows:

first repeating monomer unit with hydrophobic group

(chemical formula (2))

Second repeating monomer unit having hydrophilic group

(chemical formula (3))

Wherein R is₁And R₂Are each hydrogen or C₁-C₄An alkyl group.

The present invention also relates to a functional polymeric surfactant comprising three repeating monomeric units (a first repeating monomeric unit, a second repeating monomeric unit, and a third repeating monomeric unit), the FPS having an oil-water IFT value of not less than about 0.1 dynes/cm, preferably about 0.1 to about 15 dynes/cm, according to the formula:

first repeating monomer unit with hydrophobic group

(chemical formula (2))

Second repeating monomer unit having hydrophilic group

(chemical formula (3))

A third repeating monomer unit

(chemical formula (4))

Wherein R is₁And R₂Are each hydrogen or C₁-C₄An alkyl group.

The present invention also relates to a functional polymeric surfactant comprising the polymerization reaction product of three repeating monomer units, the FPS having an oil-water IFT value of not less than about 0.1 dynes/cm, preferably from about 0.1 to about 15 dynes/cm, according to the formula

First repeating monomer

(chemical formula (5))

Second repeating monomer

(chemical formula (6))

Third repeating monomer

(chemical formula (7))

Wherein R is₁And R₂Are each hydrogen or C₁-C₄An alkyl group.

Disclosure of Invention

To facilitate an understanding of the present invention, the following definitions are provided for some of the meanings of the terms. The terms defined herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. Words such as "a" or "the" do not refer to only a single entity, but include the general class to which a particular instance of the description pertains. The terminology used herein is for the purpose of describing particular embodiments of the invention and is not intended to be limiting of the invention, except as defined by the claims.

The "reservoir environment" as referred to herein refers to temperature, pressure, salinity, and other common formation conditions.

By "polymer" as used herein is meant a molecule having a single molecular weight of at least 1000 g/mole, the structure of which comprises multiple repeats of units derived, actually or theoretically, from molecules of relatively low molecular weight.

The term "copolymer" or "heteropolymer" as used herein refers to a polymer formed by the polymerization of two or more monomers, as opposed to a homopolymer using only one monomer.

The term "polymeric" as used herein is meant to include polymers.

The "surfactant" in the present invention means a surface active substance.

The "unit" as referred to herein refers to a portion or structural element of a polymer molecule. One unit of the polymer is covalently linked to another unit of the same structure or of a different structure.

The term "polymeric surfactant" as used herein refers to any polymer capable of acting as a fluidity control agent, which polymer is also capable of forming an emulsion.

"functional polymeric surfactant" or "FPS" as used herein refers to a polymeric surfactant having an oil-water IFT of from about 0.1 to about 15 dynes/cm (e.g., from about 0.1 to about 12.5 dynes/cm; from about 0.1 to about 10 dynes/cm); it can change viscosity in mobility control, and also can form an "emulsion" between oil and water in the reservoir environment, and should be a candidate for EOR chemistry.

"fluidity control" as used herein means in most cases that the viscosity of the polymeric surfactant solution is greater than the viscosity of water. The viscosity is the same as or greater than the viscosity of the oil to be recovered in the reservoir.

The term "emulsion" as used herein refers to a heterogeneous system of oil and water phases, including micelles, microemulsions, miscible phases, thermodynamically unstable emulsions, double emulsions and multiple emulsions.

The term "interaction" as used herein refers to the interaction between a polymeric surfactant solution and an oil that tends to form an emulsion.

"enhanced oil recovery," or "EOR," as used herein, refers to a process that generally involves the injection of one or some type of fluid into a subterranean reservoir or formation. The injected fluid and injection method supplement the natural energy in the reservoir to displace oil to the production well. In addition, the injected fluid interacts with the reservoir rock and the oil system, creating an environment conducive to oil recovery, displacement. Typical EOR methods can recover 5-25% more of the original crude oil geological reserve (OOIP) after the water wash reaches bound oil saturation. In addition, the EOR method can be used before the bound oil saturation is reached by the water washing.

The term "formation" or "subterranean reservoir" as used herein refers to the place in the earth's crust where the original hydrocarbons are present in the form of a mineral deposit. It exists anywhere 1,000-3,000 feet below the surface of the earth and varies in shape, size and age. The formation may have been eroded by water flooding, polymer injection, or chemical means.

The term "displacement fluid" or "displacement solution" as used herein refers to an aqueous solution used to enhance the recovery of oil from a subterranean formation.

The conventional theory that emulsion formation is dependent on low IFT has driven the search for ultra low IFT (10 between displacement fluid and oil)^-4-10^-2Dynes/cm) to form an oil emulsion to produce a more efficient micelle/polymer flood. The present invention demonstrates the surprising experimental conclusion that polymeric surfactants with moderate oil-water IFTs (about 0.1 dynes/cm or higher) can also effectively emulsify oil and have been demonstrated by core displacement and field experiments to be useful in EOR chemistry.

Without being bound by any theory, the low or ultra low IFT requirements recognized in the prior art may not be applicable to functional polymeric surfactants, as the functional polymeric surfactants of the present invention not only act as fluidity-controlling agents to generate viscosity, but also effectively emulsify the oil. Using FPSs that only slightly reduce IFT as the only major agent in EOR chemistry will likely revolutionize future technologies for enhanced oil recovery. Based on the present invention, one can design hundreds of new FPSs for cost-effective EOR methods.

Based on its unexpected characteristics, the FPS used in the EOR chemistry described herein can be used not only for mobility control, but also as a pseudo-surfactant to form an emulsion in the reservoir environment. The FPS can obtain both the volume sweep efficiency and the microscopic oil displacement efficiency. The main features of FPS for use in EOR water flooding are as follows: (1) an aqueous FPS solution will increase the apparent viscosity and thus reduce the fluidity of water; (2) the FPS can realize uniform penetration through selective adsorption and mechanical entrapment of the FPS on the rock; (3) the FPS may also have a certain viscoelasticity; and (4) FPS is a surfactant that reduces oil-water IFT.

Accordingly, the present invention also relates to a new and improved method for oil recovery. The method injects a functional polymer surfactant displacement fluid having a medium oil-water IFT value into a hydrocarbon-containing formation.

In one embodiment, the IFT value is from about 0.1 to about 15 dynes/cm, preferably from about 0.1 to about 10 dynes/cm, more preferably from about 0.5 to about 10 dynes/cm. IFT values can be measured by techniques well known in the art. In the present invention, the IFT value is measured by the following method: an oil phase (e.g., n-heptane) was mixed with an aqueous phase (e.g., a 3% sodium chloride solution of FPS) using a rotary drop interfacial tensiometer under 86F conditions: the interfacial tension between the two phases is measured as a function of time, typically 2 hours. If the value continues to vary between 1-2% over 20 minutes, the test is recorded.

In another embodiment, the concentration of the functional polymeric surfactant in the flooding solution or liquid is about 20ppm to about 10,000ppm, about 100ppm to about 6000ppm, about 200ppm to about 3000ppm, about 300ppm to about 1500 ppm.

In another embodiment, after oil is displaced to the production well by the natural energy source, the formation or reservoir contains residual hydrocarbons (e.g., oil). Additionally, the formation may have been washed with water to irreducible water saturation. Furthermore, the formation may have been chemically treated and considered unrecoverable.

In another embodiment, the displacement solution is passed into the formation through an injection system (e.g., an injection well) and hydrocarbons (e.g., petroleum) are recovered through a production system (e.g., a production well). In certain embodiments, the injection well is a production well. For example, in a "steam stimulation" mode, an FPS solution is injected through a well into a hydrocarbon containing formation. The injection well is then shut in for a period of time before the well is used to recover oil.

In another embodiment, the process for enhanced oil recovery using FPS generally achieves about 5-30% OOIP, preferably about 10-30% OOIP, more preferably about 15-30% OOIP, and more preferably about 15-25% OOIP.

In another aspect, the present invention relates to a functional polymeric surfactant composition. The compositions comprise a plurality of different synthetic carbon-based and silicon-based polymeric surfactants, wherein the polymeric surfactants comprise at least one hydrophilic monomeric unit and at least one hydrophobic monomeric unit and have an oil-water IFT value greater than 0.1 dynes/cm. Preferred polymeric surfactants include functionalized polyarylamines and derivatives thereof.

In another aspect, the present invention relates to a functional polymeric surfactant. Having a partially hydrolyzed polyarylamine backbone and repeating monomer units represented by the following formula. The functional polymeric surfactant has an IFT value of not less than about 0.1 dynes/cm, preferably from about 0.1 to about 15 dynes/cm:

(chemical formula (1))

R_f＝-NH₂，-ONa，-OR_L，-NHR_L，-R_LSO₃Na，-(EO)_a(PO)_bR_LQuaternary ammonium surface active groups, bis-ammonium Gemini surfactant groups, -R_LSH and the like, PO represents-CH₂-CH(CH₃) -O-and EO represents-CH₂-CH₂-O-wherein R_LIs a hydrophobic group (e.g., alkyl, phenyl, or derivatives thereof), and a + b is an integer from 6 to 30.

In another aspect, the present invention relates to a functional polymeric surfactant. Which includes a first repeating monomer unit and a second repeating monomer unit as shown in the following formula. The FPS has an oil-water IFT value of not less than about 0.1 dynes/cm, preferably from about 0.1 to about 15 dynes/cm:

first repeating monomer unit having hydrophobic group

(chemical formula (2))

Second repeating monomer unit having hydrophilic group

(chemical formula (3))

Wherein R is₁And R₂Are each hydrogen or C₁-C₄An alkyl group.

In another aspect, the present invention relates to a functional polymeric surfactant comprising three repeating monomeric units (a first repeating monomeric unit, a second repeating monomeric unit, and a third repeating monomeric unit) as shown below. The FPS has an oil-water IFT value of not less than about 0.1 dynes/cm, preferably from about 0.1 to about 15 dynes/cm.

First repeating monomer unit having hydrophobic group

(chemical formula (2))

Second repeating monomer unit having hydrophilic group

(chemical formula (3))

A third repeating monomer unit

(chemical formula (4))

Wherein R is₀，R₁And R₂Are each hydrogen (H) or C₁-C₄An alkyl group. When R is₀When it is H, the third repeating monomer unit is

In another aspect, the present invention relates to a functional polymeric surfactant. Which comprises the polymerization product of the following three repeating monomers. The FPS has an oil-water IFT value of not less than about 0.1 dynes/cm, preferably from about 0.1 to about 15 dynes/cm.

First repeating monomer having hydrophobic group

(chemical formula (5))

Second repeating monomer having hydrophilic group

(chemical formula (6))

A third repeating monomer unit

(chemical formula (7))

Wherein R is₀，R₁And R₂Are each hydrogen (H) or C₁-C₄An alkyl group. When R is₀When H is the third repeating monomer

In another embodiment, the hydrophobic group is an anionic, cationic, nonionic, zwitterionic, betaine, or zwitterionic pair. In particular, the nonionic group is [ -COO-alkyl]、[-CO-N(X₁)(X₂)]Alkyl, phenyl, or derivatives thereof, wherein X₁＝C₃-C₃₀An alkyl group; 1-3 phenyl, phenyl or C₁-C₆Cycloalkyl-substituted C₁-C₃Alkyl radical and X₂H or C₃-C₁₀An alkyl group. The cation group is quaternary ammonium salt with alkyl and phenyl or its derivative (salt is selected from-CO-CH)₂-quaternary ammonium-alkyl, -CO-NH-quaternary ammonium-alkyl, bis-ammonium Gemim surfactants and derivatives thereof).

In another embodiment, the hydrophilic group is an anionic, cationic, nonionic, zwitterionic, betaine, or zwitterionic pair. In particular, the nonionic group is [ -COO- (EO) n-alkyl]- [ -COO- (EO) c-fluoroalkyl group]Wherein n is an integer of 6 to 30, c is an integer of 6 to 30, EO represents-CH, or a derivative thereof₂-CH₂-O-. The anionic group is an organic acid salt (e.g., acrylic acid, methacrylic acid, maleic acid, itaconic acid, acrylamidomethylpropyl sulfonic acid, vinylphosphoric acid, styrenesulfonic acid, or derivatives thereof).

In another embodiment, the hydrophobic monomer is selected from the formulas shown below:

(chemical formula (8))

(chemical formula (9))

(chemical formula (10))

Or

(chemical formula (11))

Wherein R is_LIs a hydrophobic group (e.g., alkyl, phenyl, or derivatives thereof); x^-Is Cl^-Or Br^-。

In another embodiment, the hydrophobic monomer is selected from the formulas shown below:

CH₂＝CH-CO-NH-CH(CH₂-SO₃Na)((CH₂)_n-CH₃)，

(chemical formula (12))

CH₂＝CH-CH₂-N⁺(CH₃)₂-(CH₂)n-CH₃·X^-，

(chemical formula (13))

CH₂＝CH-CO-NH-(CH₂)_n-N⁺(CH₃)₂-(CH₂)_n-CH₃·X^-，

(chemical formula (14))

CH₂＝CH-CO-O-(CH₂)_n-CH₃，

(chemical formula (15))

Or

(chemical formula (16))

Wherein n is an integer of 8 to 20, X^-＝Cl^-，Br^-And G represents a bisammonium salt Gemini surfactant group. Specifically, G is represented by the following formula:

(chemical formula (17))

Where (j + k 24, j 12, 13, 14, 16, 18).

In another embodiment, the hydrophilic monomer is selected from the formulas shown below:

(chemical formula (18))

(chemical formula (19))

Or

(chemical formula (20))

Wherein R is_LIs a hydrophobic group (e.g., alkyl, phenyl, or derivatives thereof); EO is-CH₂-CH₂-O-; c is an integer of 8 to 18.

In another embodiment, the hydrophilic monomer is selected from the formulas shown below:

(chemical formula (21))

CH₂＝CH-CO-NH-C(CH₃)₂-CH₂SO₃ ^-.Na⁺，

(chemical formula (22))

Or

CH₂＝CH-CO-O-(EO)_p-(CH₂)_n-CH₃，

(chemical formula (23))

Wherein n is an integer from 8 to 20; EO is-CH₂CH₂O-; p is an integer of 6 to 20.

In another embodiment, the repeating hydrophobic monomeric units in the FPS are selected from the formulas shown below:

(chemical conversion)Learning type (24)

(chemical formula (25))

(chemical formula (26))

Or

(chemical formula (27))

Wherein R is_LIs a hydrophobic group (e.g. alkyl, phenyl or derivatives thereof), X^-＝Cl^-Or Br^-。

In another embodiment, the repeating hydrophobic monomeric units in the FPS are selected from the formulas shown below:

(chemical formula (28))

(chemical formula (29))

(chemical formula (30))

(chemical formula (31))

Or

(chemical formula (32))

Wherein n is an integer from 8 to 20; x^-Cl^-，Br^-(ii) a G represents a bisammonium salt Gemini surfactant group. Specifically, G has a structure represented by chemical formula (17).

In another embodiment, the repeating hydrophilic monomeric units in the FPS are selected from the formulas shown below:

(chemical formula (33))

(chemical formula (34))

Or

(chemical formula (35))

Wherein R is_LIs a hydrophobic group (e.g., alkyl, phenyl, or derivatives thereof); EO is-CH₂-CH₂-O-; c is an integer of 8 to 18.

In another embodiment, the repeating hydrophilic monomeric units are selected from the formulas shown below:

(chemical formula (36))

(chemical formula (37))

Or

(chemical formula (38))

Wherein n is an integer from 8 to 20; EO is-CH₂CH₂O-; p is an integer of 6 to 20.

In another embodiment, the functional polymeric surfactant includes a variety of different bio-manufactured polymeric surfactants, wherein the oil-water IFT value of the functional polymeric surfactant, either bio-manufactured or synthetic, is greater than 0.1 dynes/cm. Preferred biopolymer surfactants include xanthan gum, polysaccharides, and derivatives thereof.

Examples of the reaction of polymers with primary amines in addition to the direct reaction of the polymer with the reactants include succinic anhydride groups (which may be limited in both yield and low molecular weight, Hill et al (1993, Macromolecules, 26, pp.4521-4532.) other researchers have disclosed numerous references describing various copolymerization reactions Or mixtures thereof). By adjusting the concentration and activity of the initiator, the concentration of the monomer, the temperature and the chain-conducting medium, the molecular weight of the polyacrylate copolymer can be controlled. The monomers may be two or more.

Upon reading this disclosure, one skilled in the art will recognize that the chemical composition and, while taking into account, the degree of branching, molecular weight, and spatial conformation of the polymeric surfactant units, may also determine its utility in EOR chemistry (e.g., HLB, functional group, and ionic properties).

The following examples will further illustrate the advantages of the present invention and its embodiments. The particular materials used in the examples, amounts thereof, and other circumstances and details are not to be considered as limiting the invention. All percentages are by mass unless otherwise indicated.

Examples

Example 1.FPS example was carried out by a general experimental procedure, including the following analyses:

1) analysis of phase behavior by techniques well known in the art (see references below)

a.Reed，R.L.and Healy，R.N.：“Some Physicochemical Aspects of MicroemulsionFlooding.”Improved Oil Recovery by Surfactant and Polymer Flooding(D.O.Shahand R.S.Schechter，Eds)，Academic Press，New York，New York(1977)383-437.

b.Healy，R.N.and Reed，R.L.：“Physicochemical Aspects of MictoremulsionFlooding，”Transactions，AIME，Volume 257(1974)491-501.

c.Dreher，K.D.and Jones，S.C.：“An Approach to the Design of Fluids forMicroemulsion Flooding，”Solution Chemistry of Surfactants，Volume 2(K.L.MittalEditor)，Plenum Publishing Corporation(1979).

d.Healy，R.N.，Reed，R.L.，and Stenmark，D.G.：“Multiphase MicroemulsionSystems，”Transactions，AIME，Volume 261(1976)147-160.

e.Nelson，R.C.and Pope，G.A.：“Phase Relationships in Chemical Flooding，”Transactions，AIME，Volume 265(1978)325-338.

Emulsion type books) emulsification systems. A typical system includes hydrocarbon, water, and FPS pseudo-ternary phases. Generally, the lower the oil phase ratio, the longer the miscible flooding time, which may result in higher oil recovery because the oil has been emulsified.

2) Core Displacement experiments were performed by techniques known in the art (see references below)

f.Holm，L.W.and Knight，R.K.：“Soluble Oil Flooding，”Petroleum Engineer(November 1976).

g Gogarty，W.B.：“Rheological Properties of Pseudoplastic Fluids in Porous Media，”Journal of Petroleum Technology(June 1967)149-160.

Due to the interplay of reservoir rock and emulsions, phase and physical property studies alone are not sufficient to properly design an emulsion system. Core displacement is the key to predicting EOR characteristics in the field. A number of published documents have shown a direct correlation between core displacement results and field observations. Green et al measured factors such as the amount of adsorption, the effect of micelle slug size, and the effectiveness of fluidity control, using core displacement as one of the key design steps and criteria (1998, ISBN 1-55563) 077-4, SPETextbook Series Vol.6, pp.285). Gogarty et al used core displacement to study how to optimize surfactant concentration in field applications and simulated displacement, adsorption, fluidity control, and field scale behavior (1976, SPE 5559PA, pp.93-102).

Example 2

An exemplary sample of six FPSs was synthesized by free radical initiated copolymerization (see table one).

In the first step, acrylamide, hydrophilic monomer, lipophilic monomer and sodium carbonate are added into a three-neck round-bottom flask according to the monomer ratio in the table I, and dissolved in deionized water to form a solution, and then sodium formate and ammonia water are added. The total mass of all reactants accounted for 25-30% of the total mass of the solution in the flask.

And secondly, putting the flask into a water bath, and introducing nitrogen to deoxidize for 20 minutes. An initiation system comprising an azo initiator (e.g., ABIN), a reducing agent (e.g., sodium bisulfate), and an oxidizing agent (e.g., sodium persulfate) was added to the flask under nitrogen. The total mass of the initiating system accounts for 0.01-0.1% of the mass of all reactants.

In the third step, the flask was deoxygenated under nitrogen for another 10 minutes and then sealed. The reaction was confirmed to be completed by observing the change of the reaction solution and recording the temperature of the reaction solution.

In the fourth step, after the reaction was completed, the temperature of the water bath was raised to 185F, and the flask was kept in the water bath for 4 hours.

And fifthly, crushing, granulating and drying the synthesized gel to obtain a sample for later use.

Watch 1

Monomer	FPS-1a	FPS-1b	FPS-1c	FPS-2a	FPS-2b	FPS-2c
							Acrylamide	60-80％	60-80％	60-80％	0-40％	0-40％	0-40％
H1	0-35％	0-35％	0-35％	50-90％	50-90％	50-90％
							H2		1-5％	1-5％			1-5％
H3	1-5％	1-5％		1-5％	1-5％	1-5％
							L1			1-5％	1-5％

L2		1-5％			1-5％
							L3	1-5％			1-5％
L4	0-5％	0-5％	0-5％			1-5％
							L5	1-5％		1-5％	1-5％	1-5％	1-5％

FPS-1a, 1b, 1c each have a molecular weight between 5 million (mil) and 10 mil;

the molecular weights of FPS-2a, 2b, 2c are between 0.2mil and 3mil, respectively;

h1, H2 and H3 are all hydrophilic monomers, and

H1＝[CH₂＝CH-CO-OH]，

H2＝[CH₂＝CH-CO-NH-C(CH₃)₂-CH₂SO₃ ^-·Na⁺]，

H3＝[CH₂＝CH-CO-O-(EO)_p-(CH₂)_n-CH₃]；

l1, L2, L3, L4 and L5 are all hydrophilic monomers, and

L1＝[CH₂＝CH-CO-NH-CH(CH₂-SO₃Na)((CH₂)_n-CH₃)]，

L2＝[CH₂＝CH-CH₂-N⁺(CH₃)₂-(CH₂)_n-CH₃·X^-]，

L3＝[CH₂＝CH-CO-NH-(CH₂)_n-N⁺(CH₃)₂-(CH₂)_n-CH₃·X^-]，

L4＝[CH₂＝CH-CO-O-(CH₂)_n-CH₃]，

L5＝[CH₂＝CH-CO-G]；

n is an integer from 8 to 12;

EO represents-CH₂CH₂O-，

p is an integer from 6 to 20;

X^-＝Cl^-，Br^-

g represents a bisammonium salt Gemini surfactant group covalently bonded to a carbonyl group in the monomer, e.g.

(j+k＝24，j＝12，13，14，16，18)

The IFT test procedure shown in the following examples is as follows. The IFT values of these systems (oil phase such as n-heptane, aqueous phase such as 1000ppm FPS in 3% sodium chloride) were determined under 86F conditions using a rotary drop interfacial tensiometer. These IFT values were determined by the following method: the interfacial tension of a system is measured as a function of time, typically for 2 hours. If the last 20 minutes value continues to vary between 1-2%, the 2 hour test is recorded; if not, the test is continued until the value varies between 1 and 2% for 20 minutes. All test results are listed in table two.

The oil-water IFT test was performed on 6 FPS samples (in table one). The IFT value of the commercially available partially hydrolyzed polyacrylamide in the previous polymer drive system (MO 4000 from Mitsubishi) was 34.33 dynes/cm. The reading for the control was 44.80 dynes/cm for n-heptane and 3% sodium chloride.

Watch two

	FPS-1a	FPS-1b	FPS-1c	FPS-2a	FPS-2b	FPS-2c	MO4000	Control of
									IFT	5.34	7.29	3.47	0.91	0.86	1.36	34.33	44.80

Example 3

Core displacement tests were performed on a 12 inch core (average air permeability 487md) of epoxy coated beret sandstone at 185F. The dried cores were flushed with 2 pore volumes of strong brine until irreducible water saturation was reached, resulting in a typical crude oil with a viscosity of about 7.2 cP. The oil saturation is typically 0.65. The core was again flushed with the same brine until a residual oil saturation (98% water) of between about 0.42 and 0.65 was reached.

Chemical flooding was initiated by injecting slugs of 1500ppm FPS samples (FPS-1 a, 1b, 1c, 2a, 2b, 2c were used in 6 core displacement tests, respectively) prepared from 0.5% sodium chloride brine in 0.3 pore volumes. A further 0.5% sodium chloride brine was injected until residual oil saturation (98% moisture) was reached. The resulting residual oil saturations are listed in table three.

Another chemical drive was started by injecting a slug of 1500ppm PAM-25 (polyacrylamide, 23% hydrolysis, 25mi1 molecular weight) in 0.3 pore volumes, prepared from 0.5% sodium chloride brine. A further 0.5% sodium chloride brine was injected until residual oil saturation (98% moisture) was reached (see table three).

Watch III

	FPS-1a	FPS-1b	FPS-1c	FPS-2a	FPS-2b	FPS-2c	PAM-25
								Degree of saturation	0.30	0.35	0.32	0.27	0.29	0.30	0.38

The bound oil saturation data in table three indicate that FPS with lower molecular weight overall has better oil recovery compared to ultra high molecular weight polyacrylamide. FPS-2b was used for mature field trials at 100% water content (113F, 0.3-0.4% salinity, onshore sandstone, water flooding to bound oil saturation) to increase recovery by 9.5% over the original crude oil geological reserves.

Example 4

Two core displacement tests were performed on a 12 inch medium permeability core of epoxy coated beret sandstone at 113F. The dry core was flushed with 2 pore volumes of strong brine and then flushed with typical Daqing crude oil until the irreducible water saturation was reached. Then the core is driven by strong brine with 0.3 percent of mineralization degree until the saturation degree of bound oil (the water content is 98 percent) is reached. The cumulative recovery ratio of the core 1 after water flooding is 46% of the crude oil saturation, and the cumulative recovery ratio of the core 2 after water flooding is 47% of the crude oil saturation.

Core 1 was injected with a solution of FPS-2c (about 50 ten thousand molecular weight, 7.3cP, 0.6 pore volume) to give crude oil saturation in 17% increments.

Core 2 was injected with a PAM-15 solution (conventional polyacrylamide, about 1500 million molecular weight, 20.6cP, 0.6 pore volume) to give crude oil saturation in 10% increments.

FPS-2c has a viscosity of about one third of PAM-15 and has a recovery effect of over 70%.

Example 5

Two core displacement tests were performed on a 6 inch low permeability (50-80md) core of epoxy coated beret sandstone at 113F. The dry core was flushed with 2 pore volumes of strong brine and then flushed with typical Daqing crude oil until the irreducible water saturation was reached. Then the rock core is displaced by strong brine with 0.3 percent of mineralization degree until the saturation degree of bound oil (the water content is 98 percent) is reached.

Injection of 0.3% sodium chloride brine (0.3 pore volume) containing 100ppm FPS-2b resulted in 10% increase in crude oil saturation. This demonstrates the unusual oil recovery capability of FPS-2b even at low concentrations.

The specific embodiments described herein are intended to be illustrative of the invention and should not be construed as limiting the invention. The main features of the present invention can be applied to other embodiments and still fall within the scope of the present invention. One of ordinary skill in the art will know, or obtain by routine experimentation, equivalent methods to those described herein. All falling within the scope of the invention and the claims.

The compositions and methods of this invention are described in terms of preferred embodiments, and it will be apparent to those of ordinary skill in the art that variations and modifications in the compositions and/or methods and in the steps or in the sequence of steps of the methods described may be practiced without departing from the scope of the invention.

Claims (35)

1. A functional polymeric surfactant composition comprising:

a) a first repeating monomer unit represented by a first chemical formula

b) A second repeating monomer unit represented by a second chemical formula

c) A third repeating monomer unit represented by a third chemical formula

Wherein R is₀，R₁And R₂Are each hydrogen or C₁-C₄An alkyl group;

wherein the hydrophobic group is hydrophobic and is selected from the group consisting of anionic, cationic, nonionic, zwitterionic, betaine, and zwitterionic pairs;

wherein the hydrophilic group is hydrophilic and is selected from the group consisting of anionic, cationic, nonionic, zwitterionic, betaine, and zwitterionic pairs;

wherein the functional polymeric surfactant composition has an IFT value of from about 0.1 to about 15 dynes/cm.

2. The functional polymeric surfactant composition of claim 1 wherein the hydrophobic nonionic group is selected from the group consisting of nonionic groups comprising [ -COO-alkyl groups]，[-CO-N(X₁)(X₂)]Alkyl, phenyl, and derivatives thereof, wherein X₁＝C₃-C₁₅An alkyl group; 1-3 phenyl, phenyl or C₁-C₆Cycloalkyl-substituted C₁-C₃Alkyl radical and X₂H; or C₃-C₁₀An alkyl group.

3. The functional polymeric surfactant composition of claim 1 wherein the hydrophobic cationic groups are selected from alkyl, phenyl containing quaternary salts and derivatives thereof.

4. The functional polymeric surfactant composition of claim 3 wherein the salt is selected from the group consisting of-CO-CH₂-quaternary ammonium-alkanes-CO-NH-quaternary ammonium-alkyl, bis-ammonium based Gemini surfactants, and derivatives thereof.

5. The functional polymeric surfactant composition of claim 1 wherein the hydrophilic nonionic group is selected from the group consisting of [ -COO- (EO) n-alkyl][ -COO- (EO) n-fluoroalkyl group]And derivatives thereof, wherein n is an integer from 6 to 30 and EO is-CH₂-CH₂-O-。

6. The functional polymeric surfactant composition of claim 1 wherein the hydrophilic anion is an organic acid salt.

7. The functional polymeric surfactant composition of claim 6 wherein the organic acid is selected from the group consisting of acrylic acid, methacrylic acid, maleic acid, itaconic acid, acrylamidomethylpropyl sulfonic acid, vinylphosphoric acid, styrenesulfonic acid, and derivatives thereof.

8. A functional polymeric surfactant composition comprising the polymerization reaction product of:

a) a first repeating monomer represented by a first chemical formula

b) A hydrophobic monomer represented by the second chemical formula

c) A hydrophilic monomer represented by the third chemical formula

Wherein R is₀，R₁And R₂Are each hydrogen or C₁-C₄An alkyl group;

wherein the hydrophobic group is hydrophobic and is selected from the group consisting of anionic, cationic, nonionic, zwitterionic, betaine, and zwitterionic pairs;

wherein the hydrophilic group is hydrophilic and is selected from the group consisting of anionic, cationic, nonionic, zwitterionic, betaine, and zwitterionic pairs;

wherein the functional polymeric surfactant composition has an IFT value of from about 0.1 to about 15 dynes/cm.

9. The functional polymeric surfactant composition of claim 8 wherein the hydrophobic nonionic group is selected from the group consisting of nonionic groups including [ -COO-alkyl groups]，[-CO-N(X₁)(X₂)]Alkyl, phenyl, and derivatives thereof, wherein X₁＝C₃-C₁₅An alkyl group; 1-3 phenyl, phenyl or C₁-C₆Cycloalkyl-substituted C₁-C₃Alkyl radical, and X₂H; or C₃-C₁₀An alkyl group.

10. The functional polymeric surfactant composition of claim 8 wherein the hydrophobic cationic groups are selected from alkyl, phenyl containing quaternary salts, and derivatives thereof.

11. The functional polymeric surfactant composition of claim 10 wherein said salt is selected from the group consisting of-CO-CH₂-quaternary ammonium-alkyl, -CO-NH-quaternary ammonium-alkyl, bis-ammonium salt Gemini surfactants, and derivatives thereof.

12. The functional polymeric surfactant composition of claim 8 wherein the hydrophilic nonionic group is selected from the group consisting of [ -COO- (EO) n-alkyl][ -COO- (EO) n-fluoroalkyl group]And derivatives thereof, wherein n is an integer from 6 to 30 and EO represents-CH₂-CH₂-O-。

13. The functional polymeric surfactant composition of claim 8 wherein the hydrophilic anion is an organic acid salt.

14. The functional polymeric surfactant composition of claim 13 wherein the organic acid is selected from the group consisting of acrylic acid, methacrylic acid, maleic acid, itaconic acid, acrylamidomethylpropyl sulfonic acid, vinylphosphoric acid, styrenesulfonic acid, and derivatives thereof.

15. The functional polymeric surfactant composition of claim 8 wherein the hydrophobic monomer is selected from the group consisting of CH₂＝CH-CO-OH，CH₂＝CH-CO-NH-C(CH₃)₂-CH₂SO₃Na and CH₂＝CH-CO-O-(EO)_p-(CH₂)_n-CH₃Wherein n is an integer of 4 to 20, p is an integer of 6 to 20, E is-CH₂CH₂O-。

16. The functional polymeric surfactant composition of claim 8 wherein said hydrophilic monomer is selected from the group consisting of CH₂＝CH-CO-NH-CH(CH₂-SO₃Na)((CH₂)_n-CH₃)，CH₂＝CH-CH₂-N(CH₃)₂-(CH₂)_n-CH₃，X，CH₂＝CH-CO-NH-(CH₂)_n-N(CH₃)₂-(CH₂)_m-CH₃，X，CH₂＝CH-CO-O-(CH₂)_n-CH₃And CH₂-CH-CO-G, wherein n and m are each an integer from 4 to 20; x is F^-、Cl^-、Br^-、Ac^-、NO₃ ^-Or 1/2SO₄ ^2-And G is a Gemini cationic group.

17. The functional polymeric surfactant composition of claim 8 wherein the hydrophobic monomer is selected from the group consisting of

And

wherein R is_LIs a hydrophobic group (e.g., alkyl, phenyl, or derivatives thereof); x^-Is Cl^-Or Br^-。

18. The functional polymeric surfactant composition of claim 8 wherein the hydrophobic monomer is selected from the group consisting of

And

wherein n is an integer of 8 to 20, X^-＝Cl^-，Br^-And G represents a bisammonium salt Gemini surfactant group.

19. The functional polymeric surfactant composition of claim 8 wherein the hydrophilic monomer is selected from the group consisting of

And

wherein R is_LIs a hydrophobic group (e.g., alkyl, phenyl, or derivatives thereof); EO is-CH₂-CH₂-O-; c is an integer of 8 to 18.

20. The functional polymeric surfactant composition of claim 8 wherein the hydrophilic monomer is selected from the group consisting of

And

wherein n is an integer from 8 to 20; EO is-CH₂CH₂O-; p is an integer of 6 to 20.

21. A method for recovering hydrocarbons from a hydrocarbon containing formation, the method comprising injecting a displacement solution comprising a functional polymeric surfactant having an IFT value of from about 0.1 to about 0.5 dynes/cm into the hydrocarbon containing formation through an injection well and collecting the hydrocarbons from the production well.

22. The method of claim 21 wherein the concentration of the functional polymeric surfactant composition in the flooding solution is from about 20ppm to about 10,000 ppm.

23. The method of claim 22, wherein the concentration is from about 100ppm to about 6,000 ppm.

24. The method of claim 23, wherein the concentration is from about 200ppm to about 3,000 ppm.

25. The method of claim 21 wherein the IFT of the functional polymeric surfactant composition is between about 0.1 and about 12.5 dynes/cm.

26. The method of claim 25 wherein the IFT of the functional polymeric surfactant composition is from about 0.1 to about 10 dynes/cm.

27. The method of claim 21, wherein the hydrocarbon containing formation is subjected to a waterflood.

28. The method of claim 27, wherein the hydrocarbon containing formation has been deemed unrecoverable after being water-flooded.

29. The method of claim 21 wherein the injection well is a production well.

30. The method of claim 21 wherein said hydrocarbon is petroleum.

31. The method of claim 21 wherein the injection of the displacement solution provides a production of about 5% to about 30% of the original crude oil geological reserve.

32. The method of claim 21 wherein the functional polymeric surfactant comprises the functional polymeric surfactant composition of claims 1-20.

33. The method of claim 21 wherein the functional polymeric surfactant is biological or biosynthetic.

34. The method of claim 21 wherein the functional polymeric surfactant is selected from the group consisting of xanthan gum, polysaccharides, and derivatives thereof.

35. The functional polymeric surfactant composition of claims 1-7 wherein the repeating monomeric units are linked to each other or to another repeating monomeric unit by covalent bonds.