Case-based study for constructing knowledge-based methodologies of trouble in a borehole drilling; An Examples of borehole collapse in the Tono area, Gifu Prefecture, Japan, 2

Masunaga, Kosuke; Amano, Kenji  ; Kunimaru, Takanori

We tried to carry out a risk assessment on borehole collapse by establishing the collapse rule with applying a decision tree algorithm, in order to extract the factors and common features concerning the borehole collapse. The results suggest that collapse pattern might be characterized by a local rock characteristics and geological distribution. Moreover, the application of the collapse rule to the other location suggests that the rule might be utilized on knowledge acquisition in a case of little prior information, risk assessment and preparation of a countermeasures on the borehole collapse before drilling, and collapse prediction during drilling.