Research and Development of High-Performance Section Milling Tool for Φ 139.7-mm Casing

Casing section milling technology is widely used for sidetracking old wells or well abandonment operations. Conventional section milling tools for small- and high-steel-grade casings in deep wells pose problems, such as long cutting time, and slow section milling speed leads to a short section milling footage. This study concerns the design of a high-performance section milling tool suitable for Φ139.7-mm casing. Hydrodynamic simulation was used to optimize the internal flow channel of the tool to improve cutting efficiency. The structure and shape of the cutting teeth arrangement were optimized by LS-DYNA simulation. The blade tip comprised sharp diamond-shaped cutting teeth for an improved casing cutting efficiency. The middle of the blades consisted of internal concave teeth, with a non-uniform tooth arrangement, to improve the milling efficiency. The Φ139.7-mm casing high-performance section milling tool was used in ground experiments and field applications. The results show that the cutting time was only 3.57 min, and the milling speed exceeded 0.8 m/h in the ground experiments; when used in the field, the cutting time was only 4.50 min, the max single-pass milling footage was 15.60 m, and the average single-pass footage and milling speed were 10 m and 0.40 m/h, respectively. The improved Φ139.7-mm casing high-performance section milling tool has the advantages of reducing the cutting time, fast milling speed, and long milling footage, and offers enormous potential for broad applications.