WO2012013877A1

WO2012013877A1 - Novel polymers capable of forming microgels, methods for preparing same, and use thereof in the treatment of underground cavities

Info

Publication number: WO2012013877A1
Application number: PCT/FR2011/051359
Authority: WO
Inventors: Paul Mallo; Olivier Braun
Original assignee: Societe D'exploitation Des Produits Pour Les Industries Chimiques Seppic
Priority date: 2010-07-29
Filing date: 2011-06-15
Publication date: 2012-02-02
Also published as: FR2963348A1; FR2963348B1

Abstract

The invention relates to a polymer, characterized in that it comprises, for 100 mol %: a) 5 to 25 mol % of monomer units (A) from N,N-dimethyl acrylamide; b) 60 to 95 mol % of monomer units (B) from at least one neutral monomer selected from acrylamide, N-methyl acrylamide, N-ethyl acrylamide, methacrylamide, N-isopropyl acrylamide, N-[2-hydroxy-1,1-bis(hydroxymethyl)ethyl]propenamide [or tris(hydroxymethyl)acrylamidomethane or N-tris(hydroxymethyl)-methyl acrylamide, also known by the acronym THAM]; and c) optionally up to 15 mol % of monomer units (C) from at least one monomer comprising one or more partially or completely salified acid functions. The invention also relates to microgels obtained by the post-cross-linking thereof, and to the use thereof in the treatment of underground rock formations.

Description

Novel polymers capable of forming microgels, processes for their preparation and use in the treatment of underground cavities

The subject of the present invention is novel copolymers based on N, N-dimethylacrylamide and their use to prepare thickening gels which can potentially be used in the field of the petroleum industry, particularly the prevention of water inflow. of the Control of Profiles, of the Prevention of Sand Flows especially for the treatment of high temperature wells.

The Prevention of Water Supply processes, applied to gas or oil producing wells, allow a sustainable lowering of the water fraction produced by the well and an increase in the production of oil or gas. Polymers are sometimes used, but these remain limited to relatively low water-yielding zone permeabilities (on average less than 300 millie darcy) because of the linear size of these polymers. As they are more mechanically, thermally and chemically fragile, they are rarely used alone and they are most often added stabilizers and / or crosslinking agents. It is preferred to use polymer gels whether they are sealing gels, or diluted gels (thus having a low concentration of polymer and crosslinking). The polymer-crosslinking mixture is then injected into the well to be treated with retarded gelation kinetics, the gel taking only after a few hours in the formation around the well. However, these processes are considered unreliable and often use pollutants based on chromium salts, redox pairs, aldehyde and other chemicals often toxic and not very environmentally friendly. In addition, these current processes based essentially on polyacrylamide gels do not work in wells whose temperature is high.

These processes are described in particular in the US patents published under the numbers US 3,785,437, US 4,343,363, US 4,413,689 and US 4,413,680. They are also described in the article entitled "Gel formation of polyacrylamide in the presence of glyoxal for water control application" (A. Zaitoun et al Polymer Gels and Networks 5 (1997), pp 471-480).

European patent application published under the number EP 0 427 107 discloses a copolymer comprising 5 mol% of Ν, Ν-dimethyl acrylamide, 25 mol% of acrylamide and 70 mol% of 2-acrylamido-2-methylpropanesulphonic acid prepared by inverse emulsion polymerization and its use as a drilling fluid additive. US patent application US 2003/0008779 discloses this same type of polymer in combination with hydroxyethyl cellulose as well as the use of this combination as an additive for aqueous well treatment fluids.

The increasing number of mature fields, and the development of complex wells (horizontal wells, submarine wells, multi-branch wells) combined with the unreliability of fund separation techniques, made the self-selective treatments of Preventing Water Flows, by which the polymer-crosslinking mixture is injected throughout the open gap of the well (bullhead injection), without using mechanical means to treat localized areas.

In the case of these so-called "self-selective" treatments, since the oil or gas layers are not protected during injection, it is imperative to inject a formulation that has little effect on oil or gas permeability.

Water-soluble polymers or weak gels of water-soluble polymers are products that modify the relative permeability (so-called RPM (Relative Permeability Modifiers) products) by greatly reducing the water permeability of rocks, and weakly that of oil. or gas. They act by forming an adsorbed layer of polymer at the pore wall, which remains swollen in the passage of water, but which contracts under the effect of capillary forces when the oil or gas passes. A good product called RPM must therefore strongly and irreversibly adsorb to the rock, form a layer thickness well adapted to the pore size, have good mechanical, chemical and thermal stability, as well as a "soft" consistency. , allowing it to contract easily when passing oil or gas.

In self-selective processing ("bullhead"), it is also imperative that the placement of the injected product in the different layers is optimized. The operator will seek to minimize the penetration depth in the oil or gas layers, so as to preferentially invade the water layers. Investment control can be achieved by diversifying products that temporarily protect the oil or gas zones, or by virtue of a property inherent in the RPM agent, for example choosing a product of sufficiently large size (a few microns) not to penetrate the oil layers (usually less permeable).

The international application published under the number WO 2006/024795 discloses new micro-gels and a method for their implementation. These are crosslinked polyelectrolyte copolymers obtained by inverse emulsion polymerization in the form of an inverse latex or in the form of a powder obtained by drying the inverse latex. These copolymers, after dispersion in water, lead to the production of micro-gels of calibrated size. It is possible to calibrate the size of its micro- gels as a function of the average permeability of the layer or reservoir zone through which water is produced in greater quantity, generally permeability zones of 0.001 to some darcy (1 Darcy = 0.98693 10 ^-6 m ² ).

This technology was also published in a publication titled "Using Microgels to Shut Off Water in a Gas Storage Well" (Society of Petroleum Engineers, SPE 106042).

These microgels are very stable in temperature, mechanically stable and very respectful of the environment because of their chemical nature. They are also very easy to use because their "dispersions" propagate very easily in the underground formations. They therefore do not have the aforementioned drawbacks of gels manufactured "in situ" whether in terms of their implementation, their toxicity and their temperature resistance.

However, for certain specific reservoirs, such as those with high porosity, or to reinforce the treatment carried out by the micro-gels disclosed in WO 2006/024795, it may be advantageous to carry out a second treatment with gels made in situ but of course from gels stable at temperature and non-toxic to the environment.

The inventors have therefore sought to develop new polymers capable of forming temperature-stable and non-toxic microgels.

According to a first aspect, the invention relates to a polymer, characterized in that it comprises for 100 mol%:

a) from 5 mol% to 25 mol% of monomeric units (A) derived from N, N-dimethyl acrylamide;

b) from 60 mol% to 95 mol% of monomeric units (B) derived from at least one neutral monomer selected from acrylamide, N-methyl acrylamide, N-ethyl acrylamide, methacrylamide, N-isopropyl acrylamide, N- [2-hydroxy-1, 1-bis- (hydroxymethyl) ethyl] propenamide [or tris (hydroxymethyl) acrylamidomethane or N-tris (hydroxymethyl) methylacrylamide, also known by the abbreviation THAM];

c) Optionally up to 15 mol% of monomeric units (C) derived from at least one monomer having one or more acid functions partially or totally salified.

In the above definition, polymer refers to polymers of monomeric units from at least two monomers of different chemical structure. The term polymers therefore also includes copolymers, terpolymers, tetrapolymers and monomeric unit polymers derived from more than four monomers of different chemical structure.

By acid function, in the definition of the monomer from which the monomeric unit (C) is derived, a strong acid function or a weak acid function is designated. According to a particular aspect of the present invention, said monomeric unit (C) is derived from a monomer comprising the sulphonic function or the phosphonic function.

According to a more particular aspect of the present invention, said monomeric unit (C) is derived from 2-methyl 2 - [(1-oxo-2-propenyl) amino] 1-propanesulfonic acid (also called 2-acrylamido acid). methyl propanesulfonic acid) partially or totally salified.

According to one particular aspect of the present invention, the monomeric unit (C) is derived from a partially or totally salified carboxylic acid chosen from acrylic acid, methacrylic acid, itaconic acid, maleic acid or the like. 3-methyl-3 - [(1-oxo-2-propenyl) amino] butanoic acid.

In the definition of the present invention, the term salified indicates that it is alkali metal salts such as sodium or potassium salts, nitrogen base salts such as ammonium salt, lysine salt or monoethanolamine salt (HO-CH ₂ -CH ₂ -NI-14 ⁺ ). According to a particular aspect of the present invention, the term "salified" means that the acid function is salified in the form of a sodium salt.

Among the neutral monomers from which the monomeric units (B) are derived, acrylamide is more particularly chosen.

According to another particular aspect of the present invention, the polymer as defined above, is characterized in that it comprises for 100 mol%:

a) from 5 mol% to 20 mol% of monomeric units (A) derived from N, N-dimethyl acrylamide; and

b) from 80 mol% to 95 mol% of monomeric (B) monomeric substances derived from acrylamide.

a) from 5 mol% to 20 mol% of monomeric units (A) derived from N, N-dimethyl acrylamide;

b) from 65 mol% to 90 mol% of monomeric units (B) derived from acrylamide; and

c) from 5% to 15 mol% of monomeric units (C) derived from 2-methyl-2- [(1-oxo-2-propenyl) amino] 1-propanesulfonic acid partially or totally salified.

According to another particular aspect of the present invention, the polymer as defined above is crosslinked by a crosslinking agent chosen from diethylenic or polyethylenic compounds, and especially from diallyloxyacetic acid or one of the salts and in particular its sodium salt, triallylamine, trimethylol propanetriacrylate, ethylene glycol dimethacrylate, diethylene glycol diacrylate, diallylurea or methylene bis (acrylamide).

According to a particular aspect of the present invention, the crosslinking agent used is methylene bis (acrylamide), triallylamine or trimethylol propanetriacrylate.

The crosslinking agent is generally used in the molar proportion, expressed relative to the monomers employed, of 0.005 mol% to 1 mol%.

The invention also relates to a process for preparing the copolymer as defined above, comprising:

A step a) of preparing an aqueous solution comprising, in the desired molar proportions, Ν, Ν-dimethylacrylamide, the neutral monomer, where appropriate, the monomer comprising one or more acid functional groups partially or totally salified and / or the crosslinking agent, and if desired a transfer agent,

A polymerization step b initiated by introduction into the mixture resulting from step a) of a radical-giving initiator by homolysis; and if desired - a step c) of separating the polymer.

Step a) of the process as defined above, is generally carried out with stirring until complete dissolution of the monomers used.

Step b) of the process as defined above, is typically carried out at a temperature of about 70 ° C, and allowed to proceed until complete polymerization.

By thermal initiator is denoted in step c) of the process as defined above, thermal initiator, including azobis (isobutyronitrile) (AIBN), lauroyl peroxide or dihydrochloride 2,2'-azo bis (2 -amidinopropane).

Step c) of separating the polymer by prior precipitation of the copolymer formed at the end of step b) is carried out with a suitable precipitation solvent such as, for example, acetone, and then filtration of the precipitate. It is also possible to remove the oil by atomization of the solution obtained in step b).

The subject of the invention is also the use of the polymer as defined above, as a precursor polymer in a process for preparing microgels, by post-crosslinking said precursor polymer.

The subject of the invention is also the use of a self-invertible inverse latex of the polymer as defined above, directly obtained by inverse emulsion polymerization, as a precursor polymer in a process for the preparation of microgels, by post-crosslinking said polymer. precursor.

According to another aspect, the subject of the invention is a process for the preparation of microgels, characterized in that the polymer as defined above or the self-invertible inverse latex is dissolved in water and then cross-linked in the presence of alkaline persulfate, alkaline earthy or ammonium persulfate. In the process as defined above, the dilution is carried out in pure water or of moderate salinity and the crosslinking is carried out hot at a temperature around 70 ° C.

The dilution ratio of the polymer according to the process as defined above, is generally between 0.01% by mass and 5.00% by weight expressed as weight of copolymer relative to the total mass of the solution.

In the process as defined above, the concentration of persulfate ion in the initial solution is typically between 500 ppm and 10,000 ppm, mainly between 1000 ppm and 5000 ppm.

According to another aspect, the subject of the invention is a microgel directly obtained by post-crosslinking a polymer as defined above or an autoinversible inverse polymer latex as defined above.

According to another aspect, the subject of the invention is a process for treating underground or non-underground rock formations, and more particularly oil or gas producing wells, of water injection wells intended to sweep the hydrocarbon reservoirs (oil or gas) or gas wells or gas storage wells whose temperature is greater than or equal to 50 ° C and preferably greater than or equal to 70 ° C, characterized in that it comprises a step "injection into on said rock formation or in said well, an aqueous dispersion of the polymer or self-invertible inverse latex as defined above, containing an effective amount of alkaline persulfate, alkaline earth persulfate or ammonium persulfate.

According to a variant of this process, the persulfate is introduced after the injection of said polymer solution or self-invertible inverse latex, as defined above.

The treatment of this type of well takes place over a limited thickness on the surface of the well (a few meters). It concerns the prevention of water inflow, the prevention of gas influx, the prevention of sandstorms. It may also concern profile control, chemical flooding, injection wells, sand consolidation, clogging treatments, or abandonment of zones.

By the treatment of the puffs implemented, a polymeric hydrophilic film is formed, which covers the surface of the rock, which thus avoids its erosion.

Depending on the type of well, it may be wise to inject a preflush (water, polymer alone, diversion fluid, ...) before injecting the microgel solution.

According to a particular aspect of the process, the treatment as defined above is directed to tanks whose salinity is between 0 g / l and 350 g / l TDS, preferably between 0 g / l and 100 g / l. TDS. The main advantages of the "hydrophilic film" technique with respect to consolidation by the resins are as follows:

The implementation of non-toxic water-soluble compounds;

The use of RPM products, naturally allow to pass oil or gas;

The ability to handle the entire open interval, on thick layers and depths of several meters.

Favored placement in the most permeable areas, usually the most productive of sand and or water.

The microgels according to the invention have a high adsorption energy. They have a greater mechanical, chemical and thermal stability and make it possible to form a thick adsorbed layer, thus a thicker protective film than that formed by a linear polymer of high molecular weight. .

They allow a much easier control of the treated well and limit the risks of clogging much lower than with gelling formulations or resins.

As a result of the treatment carried out with the microgels, when the well is returned to production, a reduction of the oil or gas permeability can however occur in the hydrocarbon zone. However, once the injected fluid (microgel solution) is reproduced, it is replaced by the hydrocarbon. Because of the capillary pressure alone, the microgels which are of deformable nature, are then compressed to the wall of the pore restrictions thus allowing the hydrocarbon phase to flow to the producing well without altering its relative permeability.

The following examples illustrate the invention without limiting it. Example 1 Acrylamide / Ν, Ν-dimethylacrylamide Copolymer (93.3 / 6.7)

225 g of water are dissolved in a reactor, 50 g of a commercial solution of 50% acrylamide, 2.5 g of Ν, Ν-dimethylacrylamide and 0.1 g of V 50 ™ (2.2 '-azo-bis (2-amidinopropane) dihydrochloride sold by Wako Chemicals Industries' and 0.33 g of sodium hypophosphite After sparging with nitrogen, the reactor was heated at 70 ° C for 30 minutes.

The finished product is a transparent viscous solution but the copolymer remains linear (no crosslinking) because the medium is dilutable with water.

EXAMPLE 2 Microgel of Acrylamide / Dimethyl Acrylamide Copolymer (93.3 / 6.7) Postcrosslinked with Ammonium Persulfate In 10 g of the reaction medium obtained in the preceding example, 0.23 g of ammonium persulfate is introduced. Once heated to 70 ° C, the solution becomes highly viscous. It is not possible to dilute this solution. It is therefore a gel (crosslinked polymer). Example 3: Acrylamide terpolymer / sodium Ν, Ν-dimethylacrylamide / 2-methyl-2-f (1-oxo-2-propenyl) aminol-1-propanesulfonate (80/10/10)

43.4 g of a 50% by weight aqueous solution of acrylamide, 3.5 g of Ν, Ν-dimethylacrylamide, 15.7 g of a commercial solution containing 55% by weight of the sodium salt are mixed in a reactor. 2-acrylamido-2-methylpropanesulfonic acid sodium, 225 g water, 0.1 g V50 ™ and 0.33 g sodium hypophosphite. After sparging with nitrogen, the reactor is heated at 70 ° C for 30 minutes. After polymerization, a solution of the expected linear polymer is obtained.

EXAMPLE 4 Microgel of acrylamide terpolymer / sodium Ν, Ν-dimethylacrylamide / 2-methyl 2-Γ (1-omega-2-propenyl) aminol-1-propanesulfonate (80/10/10) post-crosslinked with persulfate d 'ammonium

The procedure is the same as in Example 2, from 10 g of the reaction medium obtained in Example 3, and 0.23 g of ammonium persulfate. Once heated to 70 ° C, the solution becomes viscous. It is not possible to dilute this solution. It is therefore a gel (crosslinked polymer).

EXAMPLE 5 Acrylamide terpolymer / Ν, Ν-dimethyl acrylamide / 2-methyl 2-Γ (1-χo-2-propenyl) aminol 1-propanesulfonate sodium bis (75/10/15) cross-linked with methylene bis (acrylamide)

682 g of an aqueous solution are prepared in a reactor from 266.25 g of a 50% aqueous solution of acrylamide, 24.75 g of N, N-dimethylacrylamide, 156.1 g. a commercial solution at 55% by weight of the sodium salt of 2-acrylamido-2-methyl propanesulfonic acid, 225 g of water and 0.019 g of methylene bis (acrylamide).

This aqueous phase is emulsified in 220 g of ISOPAR ™ M using 20 g of MONTANE ™ 80 VG and 5 g of HYPERMER ™ 2296.

The polymerization is conducted with the neck cumene hydroperoxide / sodium metabisulfite.

When the polymerization is complete, 50 g of LAURETH ™ 7 are added. EXAMPLE 6 Cross-linked terpolymer acrylamide / N, N-dimethylacrylamide / 2-methyl-2-f (1-oxo-2-propenyl) aminol 1-propanesulfonate inverse latex microgel (75/10/15) postcrosslinked to Using ammonium persulfate 10 g of the reaction mixture obtained in Example 5 is dispersed with stirring.

490 g of water. A gel is obtained which, after addition of persulfate and 70% heating, becomes more compact which reveals additional crosslinking.

It is found that the microgels obtained in the preceding examples do not therefore contain toxic species and are stable in temperature. They are thus advantageously distinguished from the prior art gels commonly used in the treatment of wells and cavities underground. Indeed, these compounds of the prior art are based on homopolyacrylamides and partially hydrolyzed polyacrylamides or acrylamide / sodium acrylate copolymers are crosslinked with the aid of heavy metal salts such as chromium or glyoxal. These latter gels do not withstand temperatures above 60 ° C unlike post-crosslinked polymers object of the present invention.

Claims

claims

1. Polymer, characterized in that it comprises for 100 mol%:

b) from 60 mol% to 95 mol% of monomeric units (B) derived from at least one neutral monomer selected from acrylamide, N-methyl acrylamide, N-ethyl acrylamide, methacrylamide, N-isopropyl acrylamide, N- [2-hydroxy-1, 1-bis- (hydroxymethyl) ethyl] propenamide [or tris (hydroxymethyl) acrylamidomethane or N-tris (hydroxymethyl) methylacrylamide, also known by the abbreviation THAM]; and

2. Polymer as defined in claim 1, characterized in that it comprises for 100 mol%:

b) From 80% to 95% molar of monomeric monomers (B) derived from acrylamide.

3. Polymer as defined in claim 1, characterized in that it comprises for 100 mol%:

b) from 65 mol% to 90 mol% of monomeric monomers (B) derived from acrylamide; and

4. Polymer as defined in any one of claims 1 to 3, characterized in that it is crosslinked by a crosslinking agent selected from methylene bis (acrylamide), triallylamine or trimethylol propanetriacrylate.

5. Process for the preparation of the copolymer as defined in any one of Claims 1 to 4, comprising: A step a) of preparing an aqueous solution comprising, in the desired molar proportions, Ν, Ν-dimethylacrylamide, the neutral monomer, where appropriate, the monomer comprising one or more acid functional groups partially or totally salified and / or the crosslinking agent, and if desired a transfer agent,

A polymerization step b initiated by introduction into the mixture resulting from step a), of a thermal initiator; and if desired

A step c) of separating the polymer.

6. Use of the polymer as defined in any one of claims 1 to 4, as a precursor polymer in a process for preparing microgels, by post-crosslinking said precursor polymer.

7. Use of a self-invertible inverse latex of the polymer as defined in any one of claims 1 to 4, directly obtained by inverse emulsion polymerization, as a precursor polymer in a microgel preparation process, by post-crosslinking. said precursor polymer.

8. Process for the preparation of microgels, characterized in that the polymer as defined in any one of Claims 1 to 4, or said self-reversible inverse latex of the polymer as defined in any one of Claims 1 to 4, is dissolved in water and then crosslinked in the presence of alkaline persulfate, alkaline earth metal or ammonium persulfate.

9. Microgel directly obtained by post-crosslinking a polymer as defined in any one of claims 1 to 4, or a self-reversing inverse latex polymer as defined in any one of claims 1 to 4. 3.

10. Process for the treatment of underground or non-underground rock formations, and more particularly of oil or gas producing wells, of water injection wells intended to sweep hydrocarbon reservoirs or mine gas wells or storage wells. gas whose temperature is greater than or equal to 50 ° C and preferably greater than or equal to 70 ° C, characterized in that it comprises a step of injection into said rock formation or into said well of an aqueous dispersion polymer as defined in any one of claims 1 to 4, or self-reversible inverse polymer latex as defined in any one of claims 1 to 4, containing an effective amount of alkali persulfate, alkaline persulfate -terrous or ammonium persulfate.

1 1. Variant of the process as defined in claim 10, wherein the persulfate is introduced after the injection of said polymer solution or self-invertible inverse latex as defined above.