High-density oil-based drilling fluids are applied in salt-gypsum formations and subsalt formations in KES1103.The downhole losses is one of the main complexities in the process of drilling operation. There are 30 times of downhole losses with the total leakage of oil-based drilling fluids of 5028 cubic meter. This lost circulation in KES1103 basically contains the most common types of downhole losses in this Block, including lost circulation in carding salt bottom, lost circulation in fractured pay zones, lost circulation at casing shoe, multiple sets of formation pressure coefficient in the same spudded in interval, the leakage point is not easy to determine, so it will bring great challenge to plugging technology. A series of high-efficiency plugging technology, including highly acid soluble settlement spacer technology, bridge plugging technology with oil-based drilling fluids, bridge plugging technology with water-based drilling fluids, high water loss plugging technology, Reiter bridge plugging technology, are applied in KES1103, and the formation pressure-bearing capacity of formations had been improved significantly, achieving the purpose of quick lost circulation treatment. It provides strong technical support for “safe, efficient and economical” drilling and completion of deep Wells under complex geological conditions and for accelerating the process of exploration and development.