Lightweight oil and gas well proppants

A low density, high strength proppant comprising solid ceramic sintered pellets having a dry specific gravity of 3.0 or less produced by the steps of:

• pelletizing a milled, calcined kaolin clay powder which is substantially free of mullite and crystobalite by simultaneously mixing and compacting said powder while adding water at a controlled rate, and adding additional amounts of said powder at a controlled rate while continuing said mixing to form pellets therefrom in a desired size range;
• and
• drying and sintering said pellets.

A low density, high strength proppant comprising solid ceramic pellets, said pellets consisting essentially of a sintered kaolin clay having a dry specific gravity of 3.0 or less, said proppant having a conductivity of at least 4,400 md-ft after 50 hours at 8,000 psi and 275.degree. F. in the presence of a deoxygenated aqueous 2% solution of KCl as measured by the Stim-Lab Technique, said kaolin clay having been calcined before compaction at a temperature below that which would cause the transformation of any significant portion of said clay to mullite or crystobalite for a time sufficient to reduce the LOI of said clay to 12% or less when tested at 1400.degree. C.

A low density, high strength proppant comprising solids ceramic pellets consisting essentially of mullite and crystobalite, said pellets containing less than about 10% of a glassy phase, said proppant having a dry specific gravity of 3.0 or less and a conductivity of at least 4,400 md-ft after 50 hours at 8,000 psi and 275.degree. F. in the presence of a deoxygenated aqueous 2% solution of KCl as measured by the Stim-Lab Technique.