Abstract:

Friction between the rock and bit during drilling generates heat, causing thermal stress and rock failure. About 80% of the bit’s energy is released as heat, 1.5–10% causes residual bit changes, and 8–10% is used for rock destruction. Temperature variation was analyzed at different depths with the drill bit at 6 mm. Interface temperatures were 56°C, 49°C, 45°C, 43.5°C, and 40°C for all 5 types of rock samples considered. Temperatures at 14mm, 22 mm, and 30 mm were also recorded, stabilizing at 23°C for all rock types at 30 mm. The highest temperature at 6 mm gradually decreased to 30 mm, indicating low heat transfer in rocks. FGS (grey), FGS (pink), and shale, with SiO₂ contents of 16.45%, 30.22%, and 25.54% (wt.%), had coefficient of wear rate of 0.2121, 0.2742, and 0.1871 mg/Nm and bit-rock interface temperatures of 84°C, 147°C, and 89°C were achieved