Flexible directional drilling apparatus and method

A bottom hole assembly to directionally drill a subterranean formation, the bottom hole assembly comprising:

• a drill bit;
• a stabilizer assembly located proximate to and behind the drill bit;
• a drilling assembly comprising a drive mechanism and a directional mechanism;
• and
• a flex member located between the drilling assembly and the stabilizer assembly.

A method to directionally drill a subterranean formation, the method comprising:

• positioning a stabilizer assembly behind a drill bit;
• positioning a flex member between an output shaft of a drilling assembly and the stabilizer assembly;
• wherein the output shaft of the drilling assembly is located below a directional mechanism of the drilling assembly;
• rotating the drill bit, stabilizer assembly, and flex member with the drilling assembly to penetrate the formation;
• and
• directing a trajectory of the drill bit and stabilizer assembly with the directional mechanism.

A flex member located between a directional drilling assembly and a stabilized drill bit, the flex member comprising:

• a reduced moment of inertia portion extending between the stabilized drill bit and an output shaft of the directional drilling assembly;
• a transition region located between the reduced moment of inertia portion and the stabilized drill bit;
• and
• wherein the reduced moment of inertia portion is configured to be locally flexible along a length thereof relative to components of the directional drilling assembly.

A method of drilling a borehole comprising:

• disposing a drill bit and a stabilizer assembly at a distal end of a drillstring;
• disposing a flex member between a drilling assembly and the stabilizer assembly;
• drilling the borehole with the drill bit and the drilling assembly;
• and
• stabilizing the drill bit with stabilizer pads of the stabilizer assembly.

A method to directionally drill a subterranean formation, the method comprising:

• positioning a stabilizer assembly behind a drill bit;
• positioning a flex member in a housing of a drilling assembly;
• rotating the drill bit and stabilizer assembly with the drilling assembly to penetrate the formation;
• and
• directing a trajectory of the drill bit, and stabilizer assembly with a directional mechanism of the drilling assembly.

A bottom hole assembly to directionally drill a subterranean formation, the bottom hole assembly comprising:

• a drill bit;
• a stabilizer assembly located behind the drill bit;
• a drilling assembly comprising a drive mechanism and a directional mechanism;
• and
• a flex member located within a housing of the drilling assembly.