Abstract: To address the problems in fractured limestone formations in M oilfield,such as hard bridging by traditional lost circulation materials,poor plug formation with cement slurry,frequent pipe sticking caused by long-term lost circulation,and drilling a new hole after lost circulation control with cement slurry,the self-bonding bentonite cement slurry control technology was used for the first time in FQN-X well of M oilfield. An innovative one trip BHA （bottom hole assembly） process was adopted to complete operations such as wellbore cleaning,forced drilling through leaking layer,pumping of self-bonding bentonite cement slurry,and plug removal. The lost circulation control efficiency is increased 400%,ensuring downhole safety,and providing reference for lost circulation control in similar fractured limestone formations.

Key words: fractured limestone, one trip BHA, self-bonding bentonite cement, lost circulation