Patent ID: 7067445

Claim:
A method of forming a proppant mixture comprising: combining a particulate material with a liquid to form a mixture; forming the mixture into spherical pellets; screening the pellets; and firing the pellets to provide a proppant mixture with a median diameter such that when the proppant mixture is sieved through a sequential series of mesh sizes selected from the ASTM U.S. Standard mesh sizes consisting of 10, 12, 14, 16, 18, 20, 25, 30, 35, 40, and 45, the median diameter is in a median mesh size corresponding to one of the meshes in the series, and wherein: 0–25% wt. % of the pellets are retained on the sieve having a mesh size which is two sizes preceding the median mesh in the sequence; 15–33 wt. % of the pellets are retained on the sieve having a mesh size immediately preceding the median mesh in the sequence; 15–33 wt. % of the pellets are retained on the median mesh; and 15–35 wt. % of the pellets are retained on the next subsequent mesh in the sequence.