The Michigan Geological Survey received a donation of geolographs from multiple industry members (Jimmy Miles, Jack Mortensen, and others) . Most are from the 1970’s. The logs record the drill bit penetration rate through the rock as the well was drilled for oil/gas. The red line on the logs are the penetration rates. Footages are calculated and handwritten on the logs by the mudlogger. This information is helpful in observing which lithology the bit is drilling through according to the ease and short time vs more difficult and longer times of drilling through a formation.
