On October 22, 2010, in the Daqing Oilfield Block of PetroChina, the Gangshen 64-1K well required an old well modification, with a side-drilled window at a depth of 2075 meters at an angle of 46 degrees. Since this section of the well is a dual casing (production casing and technical casing) window, conventional directional tools could not meet the windowing requirements. Our company used a new type of dual-cylinder directional tool to meet the technical challenges of large well inclination and dual casing windowing in one go, ensuring safety and reliability, high efficiency while reducing construction costs, and received unanimous praise from the industry.