Patent ID: 7491681

Claim:
An oleaginous base well drilling and servicing fluid comprising: an oleaginous base liquid; a silica viscosifier; a biopolymer thermal stabilizer, and a polar additive having the formula HO —C a H 2a —Z wherein a is an integer from 1 to about 5, Z is a radical selected from the group consisting of H and (OC b H 2b ) n OR, where b is 2, 3 or mixtures thereof, n is an integer from 0 to 3, and R is a radical selected from the group consisting of H, C x H 2x+1 , and C y H 2y+1 , wherein x is an integer from 1 to 5 and y is an integer from 1 to 3, wherein the concentration of silica viscosifier is from about 1.0 to about 10 pounds per 42 gallon barrel of the fluid and the concentration of the biopolymer is from about 0.25 to about 10 pounds per 42 gallon barrel of the fluid, and wherein the fluid has a low shear rate viscosity (LSRV) of at least 10,000 cP.