Geo N. Mitchell Drilling Co., Inc. Home Industry Links News Our Company History Management Clients Human Resources Safety Progress Graphs Illinois Basin Rotary Rigs Rigging Up... in Seminole, Oklahoma. In the 1940 s when the oil boom exploded in the Illinois Basin, George Mitchell s father, Thomas, and his four brothers migrated to Carmi, Illinois... survived depressed times and grew from a single-rig operation into one of the largest drilling contractors in the Illinois Basin. Mitchell Drilling now employs over 85 people...