US 8,757,298 B2Granted

Method and apparatus for dual speed, dual torque drilling

OwnerEdwin J. Broussard, Jr.inventor

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Abstract

A drilling unit for drilling a borehole and having an outer drill bit being rotationally driven by a primary rotary drive mechanism about a primary axis of rotation and having an outer bit cutting face disposed for drilling engagement with formation material. The outer drill bit defines an inner bit passage intersecting the outer bit cutting face. An inner drill bit is rotationally driven within the inner bit passage by a secondary rotary drive mechanism and has a secondary axis of rotation that can be the same or can be laterally offset from the primary axis of rotation. An inner bit cutting face is defined by the inner drill bit and is located within the inner bit passage. Rotation of the outer drill bit for borehole drilling causes orbital rotation of the inner drill bit about the primary axis of rotation simultaneously with rotation of the inner drill bit about the secondary axis of rotation for continuously cutting away formation material at the central region of the borehole being drilled.

Claims22

Dependent claims

A method for drilling boreholes in earth formations, comprising:

rotating an outer drill bit with a primary power source about a primary axis of rotation and against an earth formation, the outer drill bit having an outer bit cutting face in cutting engagement with the earth formation and defining an inner bit chamber intersecting said outer bit cutting face and defining an inner bit chamber opening at said outer bit cutting face;
with a secondary power source independently rotating an inner drill bit having an inner bit cutting face within said inner bit chamber with said inner bit cutting face located within said inner bit chamber opening and having formation cutting engagement with the formation simultaneously with said rotating said outer drill bit in cutting engagement with the formation;
said rotating said inner drill bit being rotating said inner drill bit within said inner bit chamber about an axis of rotation that is laterally offset from said primary axis of rotation and developing an orbital pattern of formation cutting motion of said inner drill bit in cutting engagement with the formation about said primary axis of rotation responsive to rotation of said outer drill bit;
and
rotating said inner drill bit with said secondary power source independently of rotation of said outer drill bit and simultaneously with rotation of said outer drill bit with said primary power source.

2 more elements

A drilling unit for drilling a borehole in a formation material, comprising:

a primary rotary drive system;
an outer drill bit being rotationally driven by a said primary rotary drive system about a primary axis of rotation and having an outer bit cutting face disposed for drilling engagement with the formation material, said outer drill bit defining an inner bit chamber having a chamber opening at said outer bit cutting face, said inner bit chamber being of substantially cylindrical configuration and having eccentric relation with said primary axis of rotation;
a secondary rotary drive system;
an inner drill bit being rotationally driven within said inner bit chamber by a said secondary rotary drive system and having a secondary axis of rotation being laterally offset from said primary axis of rotation and having substantially concentric relation with said inner bit chamber, said inner drill bit having an inner bit cutting face located within said inner bit chamber and being disposed for cutting engagement with the formation material within said chamber opening;
and
said outer and inner drill bits being simultaneously and independently rotated for drilling within the formation.

3 more elements

A drilling unit for drilling a borehole in a formation material, comprising:

a tubular drill string being rotationally driven by a rotary drive mechanism of a drilling system and defining a fluid flow passage;
a hydraulic fluid supply system of the drilling unit having a fluid pump communicating pump energized pressurized drilling fluid to said fluid flow passage;
an outer drill bit being mounted to said drill string and being rotationally driven thereby about a primary longitudinal axis of rotation and having an outer bit cutting face disposed for cutting away an outer annular region of the formation material during rotary drilling engagement with the formation material, said outer drill bit defining an inner bit chamber having a chamber opening intersecting said outer bit cutting face and being laterally offset from said primary longitudinal axis of rotation;
an inner drill bit being rotationally driven within said inner bit chamber by a hydraulic fluid energized secondary rotary drive mechanism and having a secondary axis of rotation being laterally offset from said primary axis of rotation;
said inner drill bit having an inner bit cutting face located within said chamber opening of said outer drill bit and having a sufficient dimension for cutting away the formation material that is not cut away by said cutting face of said outer drill bit;
and
rotation of said outer drill bit for borehole drilling causing orbital rotation of said inner drill bit about said primary axis of rotation simultaneously with rotation of said inner drill bit about said secondary axis of rotation and causing sweeping of said inner bit cutting face across and cutting away a central region of the formation material of the borehole being drilled while the majority of the formation material of the borehole is cut away by the cutting face of said primary drill bit.

4 more elements

Dependencies are inferred from the claim text.