Roy Thomas Powell

US Patent:

20060237234, Oct 26, 2006

Filed:

Apr 25, 2005

Appl. No.:

11/114926

Inventors:

Mahlon Dennis - Kingwood TX, US
Thomas Dennis - Kingwood TX, US
Eric Twardowski - Spring TX, US
Roy Powell - Estes Park CO, US

International Classification:

E21B 10/36
E21B 4/00
E21B 10/26

US Classification:

175095000, 175406000

Abstract:

An earth boring tool includes two coaxially-aligned, positive displacement motors. One motor turns a pilot bit and the other turns a reamer concentric with the pilot bit. The central bit bores the center of the hole and the reamer enlarges it. The central bit is rotated relatively faster, while rotation of the larger diameter reamer is relatively slow. The tool can thus be used to bore larger diameter holes without slowing drilling rates or adversely affecting performance of the cutter elements due to higher tangential velocities.