Patent ID: 8173176

Claim:
A composition, comprising: a plurality of substantially spherical porous silica particles, at least some of the plurality of substantially spherical silica particles having a diameter of from about 100 microns to about 3000 microns; and a carrier fluid, the plurality of substantially spherical porous particles being in the carrier fluid, wherein: for at least some of the plurality of substantially spherical porous silica particles, a pore volume of the substantially spherical porous silica particles is from about 0.4 ml/g to about 1.6 ml/g; and the plurality of substantially spherical porous silica particles have a pore volume distribution such that about 70% or more of the pore volume of the plurality of substantially spherical porous silica particles is made up of pores having pore diameters which have a tolerance of about 10 nm or less on the mean pore diameter.