Reasons for drilling obstruction

Stratigraphic reasons

1. Rock mutation: Rock mutation in the formation can cause drilling to encounter obstacles, with the phenomenon of a sudden decrease or no rotation of the drill bit when entering solid materials, resulting in significant drilling tool vibration;

2. Thick weak layer: When the thickness of the weak layer is greater than or close to the diameter of the drill bit, a large amount of mud backflow will be formed, resulting in a significant increase in the closing of the drilling fluid;

3. Thick hard layer: A thick hard layer can cause the drill bit to easily wear and even cut off, resulting in a significant decrease or stagnation in drilling speed.