US Patent 7838469 Fusing materials for prevention of lost circulation

A method is given for reducing fluid loss in downhole operations such as drilling and completion. A composition containing a fusing solid is injected into the fluid loss flow path; the fusing solid fuses at formation temperature when the injection pressure is released and the formation matrix surfaces forming the flow path close on the composition. The fusing solid is gilsonite, or a similar material, or resin coated particles. The composition may optionally contain one or more of fibers, flakes, an activator, and a dispersant.