US Patent 7087555 Drilling fluids comprising sized graphite particles

Drilling fluid systems, graphite particle mixtures, and methods for use thereof including: (a) drilling fluid systems having effective rheology and lubricity properties comprising a suspension of graphite particles having a particle size distribution sufficient to permit greater than 65 wt. % of the graphite particles to pass through a shaker screen having a mesh size of about 80 or less; and (b) spotting fluids having effective rheology comprising graphite particles having an average particle size of 120 mesh or greater.