k tahmasbi - petroleum university of technology
y soleymani

lost circulation or lost return is defined as the partial or total loss of whole drilling fluid to subsurface formations probably the most problematic situation is naturally fractured formations where the operator may face total loss with no mud return in the annular the voids or large fractures encountered in this case are often too large to be plugged with conventional lost circulation materials LCm hence massive lost circulation is a major and costly drilling problem new approaches to cure extreme losses are settable plugs this term is used for slurries which gel or solidify in seal zones when these fluids are being lost to the formation they should gel quickly as it travels away from the wellbore as the fluid velocity decreases some examples of such plugging products are gunks or cross linked polymers.