Reamer 4 : Tool employed to smooth the wall of a wellbore, enlarge the hole, stabilize the bit, and straighten the wellbore where kinks or doglegs are encountered. (Bul D20)
The Mudblogger (Oilfield, Energy and Related Photographs), Oil Field Glossary, TX, USA 2014. http://mudblogger.com/oilfield-glossary/, (Oil - Amer) {777}