Gifts from the 20th century-Good lessons from drilling troubles. Statistics for drilling problems and some examples for geothermal well drilling.

Drilling problems that occurred during the last 15 years within JMC-Geothermal group while drilling geothermal wells, are reviewed. BHA parting, stuck BHA, and down-time caused by poorly maintained equipment, are three major problems to be avoided. Three processes that occurred during drilling a high temperature geothermal well in Kakkonda, are also discussed. They are mud deterioration caused by high temperature borehole conditions, unsuccessful sidetracking operations, and casing wear.