Abstract:Because of fracture development in upper layer of Majing structure in Western Sichuan with low formation bearing capacity and dense well spacing, channeling with adjacent wells is easily occur in drilling process and lost circulation is often encountered, even leading to complex loss circulation. Although conventional bridge plug can be effectively used, the repeated leakage and flowing backward frequently occur for the poor formation bearing capacity with low onetime success rate. In order to improve plugging effect and onetime success rate, on the basis of the original plugging technology, efficient plugging agent was introduced, through the formula optimization in laborotory and construction process improvement, efficient bridge plug technology has been formed. The field test shows that the technology has high onetime success rate and good plugging effect, which provides a new method to solve the above mentioned complex lost circulation and has certain guiding significance for dealing with complex lost circulation.