USE OF ENCAPSULATED POLYAMINES FOR LIMITING FLUID LOSS

Abstract

The instant invention relates to a method for sealing a subterranean environment, wherein a polyurethane encapsulated polyamine is injected into the subterranean environment and is released in situ in the presence of a reactive species able to form a gel or a precipitate by a physical association and/or a chemical reaction with the released polyamine.

Claims

1. A method for sealing a subterranean environment, wherein a polyurethane encapsulated polyamine is injected into the subterranean environment, and is released in situ in the presence of a reactive species able to form a gel or a precipitate by a physical association and/or a chemical reaction with the released polyamine.

2. The method of claim 1, wherein the reactive species is a crosslinkable component able to react with the polyamine and form a tridimensional network.

3. The method of claim 2, wherein the reactive species comprises more than 2 functional groups able to react with an amine group for forming a chemical bond.

4. The method of claim 3, wherein the reactive species is selected from the group consisting of polyacrylamide, a partially hydrolysed polyacrylamide, and derivatives thereof.

5. The method of claim 2, wherein the reactive species is an epoxy compound.

6. The method of claim 2, wherein the amine groups carried by the polyamine are primary or secondary amine groups.

7. The method of claim 1, wherein the reactive species is a flocculable component able to physically interact with the polyamine.

8. The method of claim 7, wherein the amine groups carried by the polyamine are tertiary or quaternary secondary amine groups.

9. The method of claim 1, wherein the polyurethane encapsulated polyamine is obtained by a process comprising the steps of: (E1) providing a reverse emulsion containing: an oil phase comprising a curable mixture of isocyanate; and polyalkyldiene hydroxylated or polyol dispersed in said oil phase, drops of a water solution or dispersion containing the polyamine. (E2) pouring the reverse emulsion of step (E1) in a second water phase to make a multiple emulsion water/oil/water, containing, as the internal water phase, drops including the non-amine hydrophilic compound and, then, (E3) curing into polyurethane all or part of the heat curable mixture contained in the oil phase of the multiple emulsion obtained in step (E2), either at high temperature or at lower temperature.

10. The method of claim 3, wherein the more than 2 functional groups are selected from the group consisting of carbonyl, aldehyde, ketone, carboxylic acid, ester and amide groups.

11. The method of claim 4, wherein the reactive species is modified with ester functions.

12. The method of claim 11, wherein the reactive species is modified with t-butylacrylate or methylmethacrylate.

13. The method of claim 9, wherein step (E3) is conducted between 50 and 95° C.

14. The method of claim 9, wherein step (E3) is conducted between 15 and 30° C.

15. The method of claim 9, wherein step (E3) is conducted at room temperature.

Description

EXAMPLE 1

Encapsulation of a Polyethyleneimine (PEI)

Preparation of a Reverse Emulsion

[0065] 151.1 g of an aqueous medium w1 containing 50% by weight of polyethyleneimine in water (Lupasol P from BASF) was dispersed within an oil phase a follows:

[0066] The aqueous medium was dispersed within an oil phase as follows:

[0067] A mixture m1 was prepared, containing 500 g of a hydroxylated (OH functionalized) butadiene of molecular weight 2000 g/mol and an average 2.6 hydroxyl function per chain. and 500 g of a rapeseed oil methyl ester with an acid index below 0.2 mg KOH/g. 151.1 g of the aqueous medium w1 were mixed with 107.8 g of the mixture m1 to form an emulsion, and then 19.43 g of isophorone di-isocyanate trimer supplied diluted with 30% wt butyl acetate (Tolonate IDT 70B from Perstorp). was added to the formed emulsion. The particle size of the emulsion (around 100-200 μm) is set by acting on the agitation speed. The mixing time after the addition of isocyanate is set to 5 mn.

Preparation of a Multiple Emulsion

[0068] An aqueous phase w2 was prepared by mixing 111 g of NaCl and 5.05 g of xanthan gum (Rhodopol 23P available from the firm Solvay, dispersed under strong agitation during 1 hour) in 883.3 g of water.

[0069] Another aqueous phase w3 was prepared by mixing 13.86 g of Na.sub.2CO.sub.3 and 5.68 g of xanthan gum (Rhodopol 23P available from the firm Solvay, dispersed under strong agitation during 1 hour) in 994.2 g of water.

[0070] 278.3 g of the reverse emulsion as freshly obtained according to the previous step was poured slowly into 330.3 g of the phase w2 under agitation (3 blades paddle) and then 260.3 g of phase w″ were added, whereby is obtained a multiple emulsion with a PEI concentration of 8.7% by weight based on the weight of the multiple emulsion.

Formation of the Polyurethane Shells

[0071] The obtained multiple emulsion was allowed to cure at room temperature (20° C.).

EXAMPLE 2

[0072] Formation of a Gel from the Formulation of Example 1

[0073] 20 g of the formulation prepared in example 1, containing polyethyleneimine encapsulated in polyurethane shells, was mixed with 200 g of an aqueous solution comprising 5% by weight of polyacrylamide-methyl methacrylate copolymer 90-10% mol (molecular weight 100 kg/mol) in tap water.

[0074] A solution of very low viscosity, easily pumpable, is obtained (80 mPa.s at 1 s.sup.−1) and the solution remains of low viscosity at low and moderate shear after 2 hrs at 60° C. When applying a high shear using a Silverson 4LRT rotor stator blender equipped with a 2 mm square hole high shear screen workhead at 7000 rpm, a gelation is triggered (due to the liberation of the PEI which reacts with the derivative polyacrylamide), and a high viscosity is obtained after 2 hrs at 60° C. (80000 mPa.s at 1 s.sup.−1).

[0075] Gel setting is monitored using AR-G2 rheometer (from TA instruments) equipped with modified Couette cell helicoidal geometry.