Thermoset nanocomposite particles, processing for their production, and their use in oil and natural gas drilling applications
Thermoset polymer particles are used in many applications requiring lightweight particles possessing high stiffness, strength, temperature resistance, and/or resistance to aggressive environments. The present invention relates to the 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 such particles. 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. In general, its main benefits are the enhancement of the maximum possible use temperature and the environmental resistance. The other method is the incorporation of nanofillers, resulting in a heterogenous “nanocomposite” morphology. In general, its main benefits are increased stiffness and strength. 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. It also relates to the optional further improvement of the heat resistance and environmental resistance of such particles via post-polymerization heat treatment. Furthermore, it also relates to processes for the manufacture of said particles. Finally, it also relates to the use of said particles in the construction, drilling, completion and/or fracture stimulation of oil and natural gas wells; for example, as a proppant partial monolayer, a proppant pack, an integral component of a gravel pack completion, a ball bearing, a solid lubricant, a drilling mud constituent, and/or a cement additive.
1. A method for fracture stimulation of a subterranean formation having a wellbore, comprising:
injecting into the wellbore a slurry containing a nanocomposite spherical bead proppant at sufficiently high rates and pressures such that said formation fails and fractures to accept said slurry, said spherical bead proppant comprising: a polymer matrix; 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, wherein said nanofiller particles comprise at least one of fine particulate material, fibrous material, discoidal material, or a combination of such materials; and wherein said nanofiller particles are selected from the group of nanofillers consisting of: carbon black, fumed silica, fumed alumina, carbon nanotubes, carbon nanofibers, cellulosic nanofibers, fly ash, polyhedral oligomeric silsesquioxanes, or mixtures thereof, said nanofiller particles being dispersed throughout said polymeric nanocomposite spherical bead propppant, wherein said spherical bead proppant has a diameter ranging from 0.1 mm to 4 mm and wherein said spherical bead proppant has about neutral buoyancy relative to water; and
emplacing said nanocomposite spherical bead proppant within a fracture network in said formation in a packed mass or a partial monolayer of said spherical head proppant, which packed mass or partial monolayer props open the fracture network; thereby allowing produced gases, fluids, or mixtures thereof, to flow towards the wellbore.
2. The method of claim 1 , wherein said polymer matrix comprises a styrene-divinylbenzene copolymer or a styrene-ethylvinylbenzene-divinylbenzene terpolymer.
3. The method of claim 2 , wherein said polymer matrix contains divinylbenzene in an amount ranging from 3% to 35% by weight.
4. The method of claim 1 , wherein said nanofiller comprises carbon black, possessing a length that is less than 0.5 microns in at least one principal axis direction and present in an amount from 0.1% to 15% of said nanocomposite spherical bead proppant by volume.
5. The method of claim 1 , wherein said packed mass or said partial monolayer exhibits a static conductivity of at least 100 mDft after 200 hours at a temperature greater than 80° F.