▎ 摘　　要

NOVELTY - Reduction in lost circulation in a wellbore involves introducing (i) a fluid comprising a fluid loss control additive (100) comprising a shape memory polymer and/or a shape memory alloy into the wellbore, allowing (ii) the fluid loss control additive to lodge within fractures within a subsurface formation in the wellbore, and allowing (iii) the fluid loss control additive to expand within the fractures, thereby forming a barrier between the wellbore and the subsurface formation to reduce lost circulation in the wellbore. USE - Reduction in lost circulation in wellbore in oil and gas industry. ADVANTAGE - The method enables easy, economical and efficient reduction in lost circulation in wellbore. DESCRIPTION OF DRAWING(S) - The drawing shows a schematic view of the fluid loss control additive. Fluid loss control additive (100) Compressed form (110) Expanded form (120) Fronds (130)