Composition and method for making a proppant
The present invention relates to proppants which can be used to prop open subterranean formation fractions. Proppant formulations are further disclosed which use one or more proppants of the present invention. Methods to prop open subterranean formation fractions are further disclosed. In addition, other uses for the proppants of the present invention are further disclosed, as well as methods of making the proppants.
1. A method of forming a proppant, comprising blowing into template spheres with a coaxial blowing nozzle, a suspension or dispersion comprising inorganic or organic solid particles having particle diameters in the range of from 0.001 to 10 microns and heating said template spheres to evaporate any liquid from said suspension or dispersion, and then optionally hardening the template spheres, and further providing a shell around the entire outer surface of said template spheres and then sintering said shell to form a continuous sintered shell.
2. A method of forming a proppant, comprising:
a) forming template spheres by tumbling together and mixing (1) solidifiable liquid material comprising a thermally fugitive organic binder material and a source of void-forming agent adapted to evolve as a gas and convert the liquid material to a template sphere and (2) a mass of minute discrete free-flowing inorganic heat-sinterable parting agent particles selected from metals, metalloids, metal oxides and metal salts that are wetted by, and at least partially absorbed into, the liquid material during the tumbling action to form liquid spheres; sufficient parting agent particles being present so that any portion of liquid material uncovered by parting agent particles tumble against discrete unabsorbed parting agent particles;
b) providing conditions during the tumbling action, and tumbling for a sufficient time for the void-forming agent to evolve as a gas and form a central interior space within the liquid spheres and for the thus-hollowed liquid spheres to solidify;
c) collecting the spheres after they have solidified to a shape-retaining condition;
d) optionally firing the hollow spheres to first burn out the organic binder, and to then sinter the parting agent particles to form template spheres; and
e) providing a shell around the entire outer surface of said template spheres and then sintering said shell to form a continuous sintered shell.
3. A method of forming a proppant, wherein said proppant comprises a ceramic material or oxide thereof, and said proppant has a crush strength of about 1,500 psi or greater, and said method comprises forming droplets containing ceramic material or oxides thereof with a vibrating nozzle and then solidifying said droplets into proppant spheres.
4. The method of claim 3 , further comprising forming at least one shell on said proppant spheres.
5. The method of claim 3 , wherein said proppant spheres are hollow.
6. The method of claim 4 , wherein said proppant spheres are hollow.
7. The method of claim 3 , wherein said droplets have a Krumbein sphericity of at least 0.8.
8. The method of claim 3 , wherein said droplets have a Krumbein sphericity of at least 0.9.
9. The method of claim 3 , wherein said proppant spheres have a diameter of 90 microns to about 1,600 microns.
10. The method of claim 3 , wherein said method further comprises sintering said proppant spheres to form sintered proppants.
11. The method of claim 4 , wherein said method further comprises sintering said proppant spheres to form sintered proppants.
12. The method of claim 4 , wherein said shell is a ceramic shell.