Tangdong Block of Dagang Oilfield has complex geology. The main target layers are the third member of Dongying Formation and Shahejie Formation. The target layers are deeply buried and rather thick, and the damage mechanisms between the reservoirs are very different. The applications of fine calcium carbonate and plugging agents for drilling fluids in reservoir damage prevention present insufficient performance for exploration and appraisal wells in this block, due to the low technical adaptiveness to the reservoirs and inferior practice management. The core permeability recovery rate for the reservoirs is only 67.5%. According to the core sensitivity evaluation and casting thin section analysis results of Well Tangdong 9X6, a reservoir protection technology system was developed for the drilling of the Tangdong exploration and appraisal wells, according to the potential damage factors. The protection system adopts the film-forming plugging reservoir protection technology and combines the applications of the single-well multi-layer/multi-point design method. The efficient implementation of the developed technology system is ensured with the help of refined technology implementation management and high-quality real-time evaluation. The film-forming plugging reservoir protection technology was applied to five wells in this block. The dynamic fluid loss of drilling fluids was reduced by 25.7%, and the permeability recovery rate was increased by 13.1%. All the five wells met the geological expectations. Two wells have delivered high production, with initial daily production of 61.3 t and 101.1 t, respectively, which indicates good performance.
