1
Roger Fincher, Larry Watkins, Friedhelm Makohl, Detlef Hahn: Method and apparatus for drilling boreholes in earth formations (drilling liner systems). Baker Hughes Incorporated, Madan Mossman & Sriram P C, March 6, 2001: US06196336 (187 worldwide citation)

A drilling liner having a core bit at its bottom end is carried along with a pilot bit on an inner bottom hole assembly driven by a downhole mud motor. In one embodiment, the motor is powered by mud carried by an inner string. Alternatively, the inner string may be omitted and the flow of mud throug ...


2
Finchor Roger, Watkins Larry, Makohl Friedhelm, Hahn Detlef: Methode et appareil de forage de formations terrestres (systemes de tubes de forage), Method and apparatus for drilling boreholes in earth formations (drilling liner systems). Bakers Hughes Incorporated, Bakers Hughes Incorporated, SIM & MCBURNEY, March 14, 2006: CA2291535

A drilling liner having a core bit at its bottom end is carried along with a pilot bit on an inner bottom hole assembly driven by a downhole mud motor. In one embodiment, the motor is powered by mud carried by an inner string. Alternatively, the inner string may be omitted and the flow of mud throug ...