Abstract:

The pressure sealing test is carried out to the Carboniferous reservoirs of well S119-3 at the depth of 5115 meters，after four times of unsuccessful inert material bridge plug sealing，highly effective loss circulation additive HHH combining with fresh water is applied to seal.The additive is of the characteristic of high effect，high water loss and strong leakagesealing，the analysis of high density sealing slurry indicates that its suspending property is poor，water loss is fast and the slurry is easy to deposit to the bottom of tanks，pipelines or in drilling pipes while resting，when the slurry contacts the well bore wall，water loss occurs quickly，mud cake increases in thickness，chunks are formed and the drilling pipes are easily stuck.By experimental adjustment，the amount of CMC is increased 0.15%，the suspending property of sealing slurry is enhanced and the full water loss time is delayed.The time for full water loss is longer，40~60 min more，in 2 hours，water is not completely lost，the requirement for operative time in leakage sealing design is met.The 1.46g/cm3 leakage sealing slurry does not precipitate and plug pipes，the operation is successful.

Key words: highly effective lost circulation additive, suspension ability, full water loss, leakage sealing, Tarim Basin