Thermoset nanocomposite particles, processing for thier production, and their use in oil and natural gas drilling applications
Use of two different methods, either each by itself or in combination, to enhance the stiffness, strength, maximum possible use temperature, and environmental resistance of thermoset polymer particles is disclosed. One method is the application of post-polymerization process steps (and especially heat treatment) to advance the curing reaction and to thus obtain a more densely crosslinked polymer network. The other method is the incorporation of nanofillers, resulting in a heterogeneous “nanocomposite” morphology. Nanofiller incorporation and post-polymerization heat treatment can also be combined to obtain the benefits of both methods simultaneously. The present invention relates to the development of thermoset nanocomposite particles. Optional further improvement of the heat resistance and environmental resistance of said particles via post-polymerization heat treatment; processes for the manufacture of said particles; and use of said particles in the construction, drilling, completion and/or fracture stimulation of oil and natural gas wells are described.
1. A method for producing a polymeric nanocomposite particle, exhibiting at least one of enhanced resistance to deformation under load, enhanced retention of resistance at elevated temperature, and enhanced retention of resistance in acidic, basic, or hydrocarbon environments, comprising:
preparing an organic phase comprising a reactive mixture dispersed within an organic liquid medium, containing at least one of an initiator; a dispersant; and at least one of a monomer, an oligomer or combinations thereof, said monomer and oligomer being capable of creating crosslinks between polymer chains, and from 0.001 to 60 volume percent of nanofiller particles possessing a length that is less than 0.5 microns in at least one principal axis direction; said nanofiller particles comprising at least one of fine particulate material, fibrous material, discoidal material, or a combination of such materials, said nanofiller particles being selected from the group consisting of natural nanoclays, synthetic nanoclays or mixtures thereof; wherein said nanofiller particles are substantially dispersed within the liquid medium;
mixing said organic phase with an aqueous phase to form a polymeric nanocomposite particle precursor composition;
subjecting the nanocomposite particle precursor composition to suspension polymerizing conditions; and
forming the polymeric nanocomposite particle, whereby said nanofiller particles are dispersed throughout said polymeric nanocomposite particle and wherein said polymeric nanocomposite particle has about neutral buoyancy relative to water.
2. The method of claim 1 , wherein said reactive mixture contains a crosslinking component comprising at least one of a first monomer, a first oligomer or a first combination thereof; and wherein said reactive mixture further contains a non-crosslinking component comprising at least one of a second monomer, a second oligomer or a second combination thereof.
3. The method of claim 1 , wherein said reactive mixture comprises a non-crosslinking monomer selected from the following list, or mixtures thereof: styrenic monomers, styrene, methylstyrene, ethylstyrene, chlorostyrene, chloromethylstyrene, styrenesulfonic acid, t-butoxystyrene, t-butylstyrene, pentylstyrene, alpha-methylstyrene, and alpha-methyl-p-pentylstyrene.
4. The method of claim 1 , said method further comprising using a formulation including at least one of said reactive mixture, said nanofiller particles, and additional formulation ingredients wherein said additional formulation ingredients are selected from the group of ingredients consisting of initiators, catalysts, inhibitors, dispersants, stabilizers, rheology modifiers, buffers, antioxidants, defoamers, impact modifiers, or mixtures thereof.
5. The method of claim 1 , said method further comprising subjecting said polymeric nanocomposite particle to at least one post-polymerizing process.
6. The method of claim 5 , wherein said post-polymerizing process further comprises at least one of heat treatment, stirring, sonication, irradiation, or combinations thereof.
7. The method of claim 6 , wherein said heat treatment is performed in a medium including a vacuum, a non-oxidizing gas, a mixture of non-oxidizing gases, a liquid, or a mixture of liquids.
8. The method of claim 1 , wherein a largest principal axis dimension of said polymeric nanocomposite particle does not exceed 10 millimeters.
9. The method of claim 1 , wherein the crosslinking component comprises divinylbenzene, wherein the non-crosslinking component comprises styrene, said divinylbenzene in an amount ranging from 3% to 35% by weight of the reactive mixture.
10. The method of claim 9 , wherein said non-crosslinking monomer further comprises ethylvinylbenzene.
11. The method of claim 9 , wherein said nanofiller particles possess a length that is less than 0.5 microns in at least one principal axis direction and an amount from 0.1% to 15% of said polymeric nanocomposite particle by volume.
12. The method of claim 9 , wherein said suspension polymerizing comprises rapid rate polymerizing.
13. The method of claim 9 , wherein said suspension polymerizing comprises isothermal polymerizing.
14. The method of claim 9 , said method further comprising subjecting said polymeric nanocomposite particle to at least one post-polymerizing process.
15. The method of claim 14 , wherein said post-polymerizing process further comprises at least one of heat treatment, stirring, sonication, irradiation, or combinations thereof.
16. The method of claim 14 , wherein said post polymerizing process occurs in an aqueous reactor fluid that remains after the polymerizing.
17. The method of claim 9 , said method further comprising using a formulation including at least one of said reactive mixture and additional formulation ingredients wherein said additional formulation ingredients comprise at least one of initiators, catalysts, inhibitors, stabilizers, rheology modifiers, buffers, antioxidants, defoamers, impact modifiers, or mixtures thereof.
18. The method of claim 9 , wherein said polymeric nanocomposite particle is a spherical bead having a diameter that does not exceed 10 millimeters.
19. The method of claim 18 , wherein said diameter ranges from 0.1 mm to 4 mm.