US Patent 7036591 Low density proppant

A low density, spherical proppant made from kaolin clay having an alumina content distributed homogeneously throughout the pellets, an apparent specific gravity of from about 1.60 to about 2.10 g/cc, and a bulk density of from about 0.95 to about 1.30 g/cc. The low density is achieved by controlling the time and temperature of the firing process to be from about 1200 to about 1350° C. This low density proppant is useful in hydraulic fracturing of shallow oil and gas wells.