Well treatment

1. A method for the treatment of a hydrocarbon well, which method comprises administering, down said well, polymeric particles impregnated with a well treatment chemical or precursor or generator thereof, wherein said particles have a pore volume of at least 20%, and are prepared by a process which comprises:

(A) preparing an aqueous dispersion of polymer particles containing from 0.05 to 10 times by volume, based on the polymer, of one or more first material(s) having a water-solubility of <10 −2 g/l and having a molecular weight of <5000 g/mol, said first material(s) not being an oligomer of the polymer forming the particles and being non-crystalline at the temperature at which it is incorporated into the particles and is in liquid form at the temperature at which a partly water-soluble material is introduced in step (B); and

(B) adding a partly water soluble second material, having a water-solubility of at least ten times that of said first material(s), under conditions which prevent or hinder transport of said first material(s) through the aqueous phase, whereby said second material diffuses into the polymer particles swelled with said first material(s) and increases the volume of said particles by from 20 to 1000 times, based on the polymer.

2. The method as claimed in claim 1 , wherein said polymeric particles are administered down said well before hydrocarbon production from said well begins.

3. The method as claimed in claims 1 or 2 , wherein said polymeric particles are placed in a filter in the bore-hole of said well and within the formation surrounding said bore-hole.

4. The method as claimed in claim 1 , wherein said well treatment chemical or precursor or generator thereof is selected from the group consisting of a scale inhibitor, corrosion inhibitor, wax inhibitor, asphaltene inhibitor, foamer, biocide, surfactant, oxygen scavenger and bacteria.

5. Polymeric particles impregnated with a well treatment chemical or precursor or generator thereof, wherein said particles are prepared by a process which comprises:

(A) preparing an aqueous dispersion of polymer particles containing from 0.05 to 10 times by volume, based on the polymer, of one or more first material(s) having a water-solubility of <10 −2 g/l and having a molecular weight of <5000 g/mol, said first material(s) not being an oligomer of the polymer forming the particles and being non-crystalline at the temperature at which it is incorporated into the particles and is in liquid form at the temperature at which a partly water-soluble material is introduced in step (B);

(B) adding to said aqueous dispersion obtained in step (A), a partly water soluble second material, having a water-solubility of at least ten times that of said first material(s), under conditions which prevent or hinder transport of said first material(s) through the aqueous phase, whereby said second material diffuses into the polymer particles swelled with said first material(s) and increases the volume of said particles by from 20 to 1000 times, based on the polymer; and

(C) contacting said particles obtained in step (B) with an aqueous or non-aqueous solution or dispersion of said chemical, precursor or generator thereof, and

said particles have a pore volume of at least 20%, wherein said well treatment chemical or precursor or generator thereof is a scale inhibitor selected from the group consisting of an insulin, phytic acid, phytic acid derivative and polyaspartate.

6. A hydrocarbon well treatment composition comprising a carrier liquid containing polymeric particles impregnated with a well treatment chemical or precursor or generator thereof, wherein said particles have a pore volume of at least 20%, and are prepared by a process which comprises:

(A) preparing an aqueous dispersion of polymer particles containing from 0.05 to 10 times by volume, based on the polymer, of one or more first material(s) having a water-solubility of <10 −2 g/l and having a molecular weight of <5000 g/mol, said first material(s) not being an oligomer of the polymer forming the particles and being non-crystalline at the temperature at which it is incorporated into the particles and is in liquid form at the temperature at which a partly water-soluble material is introduced in step (B);

(B) adding to said aqueous dispersion obtained in step (A), a partly water soluble second material, having a water-solubility of at least ten times that of said first material(s), under conditions which prevent or hinder transport of said first material(s) through the aqueous phase, whereby said second material diffuses into the polymer particles swelled with said first material(s) and increases the volume of said particles by from 20 to 1000 times, based on the polymer; and

(C) contacting said particles obtained in step (B) with an aqueous or non-aqueous solution or dispersion of said chemical, precursor or generator thereof,

wherein said well treatment chemical or precursor or generator thereof is a scale inhibitor selected from the group consisting of an insulin, phytic acid, phytic acid derivative and polyaspartate.

7. A tubular filter for down-hole placement containing polymeric particles impregnated with a well treatment chemical or precursor or generator thereof, wherein said particles have a pore volume of at least 20%, and are prepared by a process which comprises:

(A) preparing an aqueous dispersion of polymer particles containing from 0.05 to 10 times by volume, based on the polymer, of one or more first material(s) having a water-solubility of <10 −2 g/l and having a molecular weight of <5000 g/mol, said first material(s) not being an oligomer of the polymer forming the particles and being non-crystalline at the temperature at which it is incorporated into the particles and is in liquid form at the temperature at which a partly water-soluble material is introduced in step (B); and

(B) adding to said aqueous dispersion obtained in step (A), a partly water soluble second material, having a water-solubility of at least ten times that of said first material(s), under conditions which prevent or hinder transport of said first material(s) through the aqueous phase, whereby said second material diffuses into the polymer particles swelled with said first material(s) and increases the volume of said particles by from 20 to 1000 times, based on the polymer.

8. The filter as claimed in claim 7 , wherein said filter comprises a particulate filter matrix of which said polymeric particles constitute 2 to 30% wt.

9. The filter as claimed in claim 7 or 8 , wherein said well treatment chemical or precursor or generator thereof is selected from the group consisting of a scale inhibitor, corrosion inhibitor, wax inhibitor, asphaltene inhibitor, foamer, biocide, surfactant, oxygen scavenger and bacteria.

10. The method as claimed in claim 4 , wherein said particles are impregnated with a scale inhibitor selected from the group consisting of insulin, phytic acid, phytic acid derivative and polyaspartate.