Abstract: An environmentally safe lost circulation material and method of use which provides effective drill bit lubrication over a wide temperature range and allows drilling in a variety of porous or fractured subterranean structures. The lost circulation material comprises generally pelletized cottonseed hulls together with between approximately 0.001% and 0.01% by weight of preservative. In another preferred embodiment of the invention, the lost circulation material comprises of between approximately 98% and 99.5% by weight of pelletized cottonseed hulls, between approximately 0.5% and 2.0% by weight of corn starch, between approximately 0.001% and 0.01% by weight of surfactant, and between approximately 0.001% and 0.01% by weight of preservative. In another preferred embodiment, the lost circulation material comprises between approximately 50% and 80% by weight of pelletized cottonseed hulls, between approximately 10% and 40% by weight of pelletized wood, between approximately 0.

Abstract: A method is disclosed for preventing loss of aqueous drilling fluid to porous formations penetrated by a well bore during drilling operations for oil and gas. The method utilizes readily available pelleted cottonseed hulls as the lost circulation material which is added to the drilling fluid and pumped down the well bore. The pelleted cottonseed hulls are composed of cottonseed hulls, cottonseed meal, bentonite, a residual amount of cottonseed lint and a surface active agent. The cottonseed hulls, cottonseed meal, bentonite, residual lint and surface active agent are heated in the presence of steam and compressed to form pellets. Because the pellets are in a compressed form, they do not expand when added to the drilling fluid until they are well down the well bore. The pelleted cottonseed hulls may also contain cottonseed oil. The pelleted cottonseed hulls are well known and widely used in the dairy cattle industry as a pelleted feed material.