METHODS FOR CONTROLLING LOST CIRCULATION IN A SUBTERRANEAN WELL AND MATERIALS THERE FOR

摘要

Method for controlling lost circulation in a subterranean well using oil-dispersible lost-circulation materials which comprise fibers that are coated (or sized) with a lipophilic coupling agent, a lipophilic film-forming polymer or both. The fibers are preferably between about 6 mm and about 25 mm long, and between about 10 µm and about 200 µm in diameter. The fibers may be added to carrier fluids comprising oil -base fluids, synthetic-base fluids, invert- emulsion-base fluids and combinations thereof. The preferred fiber concentration in the carrier fluid is between about 0.55 g/L and about 28.5 g/L. The carrier fluid may be a drilling fluid, a spacer fluid or a lost-circulation pill.