JPS6153303A - Manufacture of reversed microlatex - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method for producing t1 anti-inversion microlatex by polymerizing a water-soluble vinyl monomer in an inversion microemulsion, as well as an inversion produced by the method. Regarding microlatex.

By polymerization in an inverted emulsion resulting from a mixture of an aqueous phase comprising one or more (co)polymerized water-soluble monomers', an organic phase and one or more surfactants,
It is known to produce water-soluble [i-form inversion latex].

In these formulations, the surfactants are mostly non-ionic surfactants and are chosen among those that exhibit a small HLB (hydrophilic-lipophilic balance) and are capable of obtaining water-in-oil emulsions. Often the monooleate or monostearate of sorbitan is used. Additionally, it has been shown that certain surfactants with larger HLB (≧7) can also produce water-in-oil emulsions.

A major disadvantage of inverted latex is its lack of stability. This manifests itself in the formation of a significant amount of supernatant over time.

On the other hand, as prior art, a method for producing inverted microlatex using anionic or cationic surfactants has also been described (French Patent Application Box A-2,524,
No. 895).

The inventors have discovered, over the prior art, a method for producing inverted microlatex using nonionic surfactants that can increase the content of water-soluble polymers in the inverted microlatex.

Solution to the Problem The method for producing inverted microlatex of the present invention is generally defined by the following steps.

(a) a (stable and transparent) water-in-oil microemulsion diphen; (+) an aqueous solution of an alkali metal salt of vinyl monomer and a saturated aliphatic monocarboxylic acid to be polymerized; and (11) at least one hydrocarbon. (iii) an oil phase containing a liquid in the presence of at least one nonionic surfactant having an HLB of 8 to 11 (in the case of mixtures of surfactants, with respect to the resulting HLB);
, mixed and produced: (b) The inverted microemulsion obtained in step (a) is subjected to polymerization conditions to completely polymerize, resulting in a stable, transparent, and polymeric inverted microlatex. Do it like this.

In the formulation of the microlatex-guided inverted microemulsions of the invention, the water-soluble vinyl monomers may consist of, inter alia, acrylamide, methacrylamide or N-vinylpyrrolidone. The alkali metal salts of saturated aliphatic monocarboxylic acids may be, for example, alkali salts of acetic acid, propionic acid or butyric acid. In practice sodium acetate is preferred.

To obtain inverted microemulsions, it is generally necessary to use special conditions, the main parameters of which are:

namely, the concentration of the surfactant, the HLB of the surfactant or surfactant mixture used, the temperature, the type of organic phase and the composition of the aqueous phase.

The monomer content in the aqueous phase is generally between 20 and 80
mff1%, often 30 to 70 m1%.

Alkali metal carboxylate and 1! The weighting of the amount of polymer is generally from 0.1/1 to 0.3/1.

In some cases, the aqueous phase may include sodium hydroxide or potassium hydroxide.

In this way, m of this substance is precisely adjusted to obtain hydrolyzed polyacrylamide.

This is particularly advantageous for some applications. It is especially advantageous for applications related to secondary recovery of hydrocarbons. One more
One technique consists of carrying out polymerization followed by hydrolysis.

The choice of organic phase is critical to the minimum temperature of the surfactant required to obtain an inverted microemulsion.

This organic phase can consist of one hydrocarbon or a mixture of hydrocarbons. Among them, paraffinic and/or isoparaffinic hydrocarbons or hydrocarbon mixtures are the most suitable for obtaining economic formulations of inverted microemulsions (low surfactant content).

The fffffl ratio of m in the aqueous phase to m in the hydrocarbon phase is chosen as large as possible so that, after polymerization, a microlatex with a high content of polymer is obtained. In practice, this ratio can be, for example, in the proportion of 0.5 to 3/1.・ In addition, the selection of surfactant (one or more types)
It is derived by obtaining an HLB ranging from 8 to 11. In fact, outside this range, it is either impossible to obtain an inverted microlatex, or a considerable amount of additional surfactant is required, making it incompatible with economical methods. Furthermore, as previously noted, within the HLB region thus defined, the surfactant content must be sufficient to obtain an inverted microlatex. A similar inversion latex would be obtained and would no longer belong to the invention.

In the range of HLB considered, a minimum of 81 degrees of surfactant over the total components of the microemulsion is
It changes according to the value of . The lower limit of about 9% by weight more specifically reaches an HLB range of about 8.5-9.5. For the ranges 8-8.5 and 9.5-11, the lower limits are generally higher. Thus, for example, for an HLB value of about 10, the minimum content of surfactant is about 20% by weight.

Regarding the upper concentration limit for surfactants, for economic reasons it is desirable to limit the temperature to 25fiff1% of the total components of the inverted microemulsion.

Importantly when making inverted microemulsions, the temperature of the mixture must be carefully controlled, as the inverted microemulsions are temperature sensitive in the presence of nonionic surfactants. This temperature effect becomes more sensitive the closer the surfactant concentration approaches the minimum content required to obtain an inverted microemulsion.

In order to reduce the required surfactant content and to eliminate as much as possible the influence of temperature on the stability of the inverted microemulsion, the inverted microemulsion is brought to the chosen temperature for polymerization as far as possible. at a temperature as close as possible to
It will have to be manufactured.

The water-soluble monomer vinyl present in the above-mentioned inverted microemulsion is polymerized by photochemical or thermal methods. That is, for example, by ultraviolet irradiation,
by photochemical polymerization or thermally by free radical generators, whether hydrophobic, such as azobisisobutyronitrile, or hydrophilic, such as potassium persulfate. This is a method of causing polymerization.

The polymerization is carried out very rapidly and quantitatively, e.g. within a few minutes by photochemical methods, to produce a stable, transparent microlatex with a particle radius of approximately 20 to 50 nm, resulting in a narrow particle size. Show the distribution.

The size of the particles dispersed in the inverted microlatex of the present invention can be determined by embossed diffusion of light. The light source on the light diffuser consists of a Spectra Physics argon ion laser operating at 488 nm.

The spread intensity temporal correlation function is obtained using a 72-channel digital correlator.

The strength correlation data is determined by the average decay time of the correlation function <U−'
＞ and the dispersion M■. The dispersion m is the magnitude of the amplitude of the decay time distribution, and is expressed as V = (<r>2-<r2>)/<r>2
2> is the quadratic efficiency of the distribution).

For polymer solutions with low polydispersity, good dispersion is linked as a first approximation to the polydispersity index Mw/Mn (weight molecules m/number molecular weight) by the relation: MW/Mn=1+4V.

The molecule m of the resulting polymer is due to the activation method chosen for the polymerization, ie photochemical activity which facilitates the attainment of very high molecular weights, as long as the polymerization temperature is maintained below 30°C. This activation method should be suitable in all cases where very high molecular weights are desired, such as in the case of inverted microlatexes that are to be used for secondary recovery of hydrocarbons.

By the process of the present invention, stable, transparent inverted microlatexes can be obtained which have a high content of water-soluble polymers, for example from about 10 to 35% by weight, usually from about 10 to 25% by weight.

The inverted microlatex obtained by the method of the invention can be used in many applications, especially in oil extraction technology. That is, it is used for secondary recovery of hydrocarbons, soil compaction, production of clay water for polling, prevention of water intrusion when extracting oil from oil wells, and as a finishing fluid or fault treatment fluid.

In general, secondary recovery methods using aqueous solutions of polymers involve injecting these solutions into the formation through at least one injection well and circulating the solutions across the formation to form at least one production well. The process consists of recovering the hydrocarbons displaced through the process.

The method of using the inverted microlatex for secondary recovery as contemplated by the present invention does not differ significantly from the method previously described for watercolor-in-oil emulsions. The inverted microlatex contemplated by the present invention is capable of self-inverting, and additional surfactants are added to facilitate inversion, as is the case in certain methods already described. This is generally not necessary. These microlatexes are used, for example after dilution in water, in a content of 50 to 5000 ppm of copolymer, preferably 100 to 2000 ppm, based on the aqueous phase formed.

Tests carried out on experimental seedlings showed the effectiveness of the inverted microlatex used.

A method of preventing water intrusion into an oil well is to inject an aqueous solution of the polymer produced by dissolving the inverted microlatex in water according to the present invention into the part of the formation to be treated from the oil well. Consists of. The polymer is highly adsorbed on the walls of the formation near the well where it is injected. When the well is then resumed, oil and/or gas will selectively pass through the treatment area, but the passage of water will be reduced.

In addition to these applications, water-soluble polymers made into microemulsions can be used as follows.

That is, for separating solids that are turbid with F3 in a liquid -
Coagulant, paper pulp! It is an auxiliary agent for flotation and dewatering in EL production, or even a flocculant in water treatment.

The inverted microlatex obtained by the method of the invention can also be used in the sizing of glass fibers, in the leather industry and also in the paint sector.

EXAMPLES The following examples are illustrative of the invention and are not to be considered limiting. Example 1.4.
10.11.15 and 16 are presented as a comparison and do not form part of the present invention.

Example 1 (comparative example) 300 g of an isoparaffin fraction having an initial boiling point of 207°C and an end point of 254°C and sorbitan sesquioleate (22(
II) and 157q of a nonionic surfactant mixture consisting of polyoxyethylene sorbitol hexaoleate (135Q). The surfactant mixture therefore has a HL of 89.3.

To the single-phase mixture thus obtained was added 0.35 g of azobisisobutyronitrile, degassed for 30 minutes and
, V, polymerize for 15 minutes at 19° C. under irradiation. This results in a cloudy and unstable latex.

Example 2 In Example 1, all else being the same, adding 159 g of sodium acetate to the aqueous phase:
After polymerization, a stable and transparent microlatex is obtained, the radius of whose particles, measured by embossed diffusion of light, is approximately 37 nm at a dispersion level of 3%.

Precipitation in acetone and successive washings with acetone and methanol gave complete conversion to polyacrylamide, the intrinsic viscosity of which was determined at 25°C in water containing 75.85 g// of NaC. , 920 cm3/g.

Example 3 In Example 2, all else being the same, the inclusion of 25.3 g of sodium acetate in the aqueous phase resulted in very similar characteristics to those described in Example 2, namely: ' R , -38 nm, a stable and transparent microlatex with dispersion = 3% is obtained.

The intrinsic viscosity of polyacrylamide, measured under the conditions given in Example 2, is 847 cm3/Q.

Example 4 (Comparative Example) If everything else is the same as in Example 2, but the amount of sodium acetate is 4.5 g, an unstable latex will be obtained after polymerization.

Example 5 The isoparaffin fraction 470Q of Example 1 and 150 g of the surfactant mixture of Example 1 are added to 378 g of an aqueous solution containing 142 q of acrylamide and 34.59 q of sodium acetate. The single-phase mixture thus obtained was
C, U, V.

Polymerize for 15 minutes under irradiation. The radius of the inverted microlatex particles thus obtained is 42.3 nm, and the amount of dispersion is 5%. The intrinsic viscosity of the obtained polymer was 25
It is 772 cm'/Q at °C.

Example 6 300 g of the isoparaffin fraction of Example 1 and 150 q of the surfactant mixture of Example 1 are added to 550 q of an aqueous solution containing 2189 acrylamide and 60.5 g of sodium acetate. The single-phase mixture thus obtained was heated to U, V at 20 °C.

A stable and transparent microlatex can be obtained by polymerizing for 15 minutes under irradiation.

The polyacrylamide isolated as described in Example 2 has an intrinsic viscosity of 878 cm3/g at 25°C.

Example 7 Dodecane 419Q and 216 g of the surfactant mixture of Example 1 are added to an aqueous solution 365Q containing acrylamide 143q and 21.4 g of sodium acetate. When the single-phase mixture thus obtained was heated at 45°C for 3 hours, 2
A stable and transparent inverted microlatex containing polyacrylamide with an intrinsic viscosity of 6350 m'/G at 5° C. can be obtained.

Example 8 In Example 7, keeping everything else the same and replacing dodecane with decane, the polymerization yield was 533 Cm3/
An inverted microlatex is obtained comprising polyacrylamide with an intrinsic viscosity of g.

Example 9 Example 7, all else being the same, replacing dodecane with heptane produces a stable transparent inverted microlatex comprising polyacrylamide having an intrinsic viscosity of 4530 m/Q at 25°C after polymerization. is obtained.

Example 10 (Comparative Example) In Example 7, all else being the same, replacing dodecane with toluene results in an unstable emulsion before polymerization.

Example 11 (Comparative Example) In Example 2, keeping all other things the same and replacing sodium acetate with sodium chloride of the same type ω, a cloudy and unstable latex is obtained after polymerization.

Examples 12-14 Under the conditions of Example 5, the respective proportions of surfactants were varied to determine the minimum amount of surfactant required to obtain a stable and transparent inverted microlatex after polymerization for various values of HLB. Measure the content. The results obtained are summarized in the table below.

*% by weight of the total starting components of the microemulsion Example 15 (Comparative) Under the conditions of Example 5, all else being the same, the proportions of the two surfactants were varied; , so that the resulting HLB is 7.5, under these conditions
It is not possible to obtain inverted microemulsions even with the addition of surfactants (more than k%).

Example 16 (Comparative Example) Under the conditions of Example 5, all else being the same, the proportions of the two surfactants were varied such that the resulting HLB was 11.5. , under these conditions it is not possible to obtain inverted microemulsions even with the addition of a large amount (more than 25% by weight) of surfactants.

Example 17 145g of acrylamide and 18t6q of sodium acetate
530 g of the isoparaffin fraction of Example 1 and 20.3 g of sorbitan sesquioleate were added to the aqueous solution 3659 containing
surfactant mixture 101 consisting of g and 80.7 (l) polyoxyethylene sorbitol hexaoleate
g. The surfactant mixture has a resulting HLB of 8.9.

To the single-phase mixture thus obtained was added azobisisobutyronitrile Q, 480, degassed for 30 minutes and
, V, polymerize for 30 minutes at 19° C. under irradiation. The result is a transparent, low viscosity inverted microlatex.

Add the isoparaffinic hydrocarbon fraction 4979 used in Example 1 and the same surfactant mixture () (LB = 8.9) 99Q as in Example 17 to an aqueous solution 404Q containing acrylamide 1680 and 20.2 g of sodium acetate. .

Polymerization is carried out under the same conditions as in Example 17.

Polymer m polymer approximately 16.8ffRi! A transparent inverted microlatex is obtained containing %.

Effects of the Invention Since the present invention is configured as described above, the content of water-soluble polymer in the inverted microlatex can be increased compared to the prior art.

Applicant for the above patent: Institut Français du Bétrol

Claims (10)

[Claims] (1) (a) The following materials, namely: - A water-soluble vinyl monomer to be polymerized and at least one alkali metal salt of a saturated aliphatic monocarboxylic acid are combined into an aqueous solution containing in a weight ratio of 0.1/1 to 0.3/1; an oil phase comprising at least one hydrocarbon liquid; and one non-hydrocarbon liquid having an HLB (hydrophilic-lipophilic balance) of 8 to 11. preparing an inverted microemulsion (watercolor in oil) by mixing a mixture of ionic or nonionic surfactants in sufficient proportions to obtain an inverted microemulsion;
(b) A method for producing an inverted microlatex, comprising the step of subjecting the inverted microemulsion obtained in step (a) to polymerization conditions. (2) The method according to claim 1, wherein in step (a), acrylamide/methacrylamide or N-vinylpyrrolidone is used as the monomer. (3) The method according to claim 1 or 2, wherein the alkali metal salt is sodium acetate. (4) The method according to any one of claims 1 to 3, characterized in that in step (a), the oil phase contains at least one isoparaffinic or paraffinic hydrocarbon. (5) Any one of claims 1 to 4, characterized in that in step (a), the weight ratio of the monomer aqueous solution to the oil phase is 0.5 to 3/1. The method described in Section 1. (6) in step (a), the proportion of the surfactant or surfactant mixture is about 9% by weight or more based on the total components of the inverted microemulsion;
A method according to any one of claims 1 to 5. (7) In step (a), the proportion of surfactant or surfactant mixture is at most 25% by weight, based on the total components of the inverted microemulsion. The method according to any one of items 1 to 6. (8) Inverted microlatex obtained by the method described in any one of claims 1 to 7. (9) Inverted microterrax according to claim 8, characterized in that the polymer content is about 10-35% by weight. (10) Within the injection well or oil extraction well, claim 8
Or a method for improving the production of hydrocarbons from oil reservoirs, characterized by injecting a polymer solution obtained by diluting the microlatex in water according to item 9.