Patent ID: 8043997

Claim:
A method for avoiding or reducing lost circulation in a subterranean formation during drilling a borehole in said formation, the method comprising: treating the subterranean formation with a lost circulation material or composition comprising: particles having a particle distribution including particles for plugging micron pores as small as about 190 microns and particles for plugging fractures ranging from about 500 to about 1000 microns; and wherein the lost circulation material comprises: about 5% to about 15% fibrous cellulosic material; about 5% to about 15% resilient graphitic carbon; about 5% to about 15% ground rubber or ground walnut shells; and about 55% to about 75% diatomaceous earth; and enhancing the tolerance of the lost circulation material to temperatures above about 150° F. to about 250° F. by adding a polymer to said lost circulation material.