Wayne Nash answers two questions from drillers this month - both relating to problems associated with bottom hole assemblies.
Got a couple questions from drillers this month - both relating to problems associated with bottom hole assemblies.%
All bits tend to walk to the le ft somewhat during normal drilling. If the bedding plane of the rock is not perfectly level (is it ever?), the bit will tend to deviate one of two ways: If the rock-face is just a few degrees off horizontal, the bit will tend to walk up-gradient. If the b edding plane is more nearly vertical, the bit will tend to walk down the rock-face. Either way, when the bit finally penetrates the rock layer and goes back into soft formation, the drill pipe will tend to go back to vertical, leaving an offset in the h ole.