Directional drilling system
AssigneeSchlumberger Technology Corporation
InventorAshley Johnson
Life of this patent
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Abstract
A directional drilling system comprises a main drill bit 24 rotatable about a main bit axis 26, a pilot drill bit 34 rotatable about a pilot bit axis 36 substantially parallel to the main bit axis 26, and adjustment means 28 for adjusting the position of the pilot bit axis 36 relative to the main bit axis 26.
Claims13
A directional drilling system comprising a main drill bit rotatable about a main bit axis, a pilot drill bit rotatable about a pilot bit axis substantially parallel to the main bit axis, and adjustment means for adjusting the position of the pilot bit axis relative to the main bit axis.
A system according to any of the preceding claims, wherein the adjustment means comprises a steering shaft which extends generally coaxially with the main bit, a drive shaft of the pilot bit being supported for rotation by the steering shaft, the drive shaft of the pilot bit being eccentric to the steering shaft.
A system according to any of the preceding claims, wherein the pilot bit is arranged to be driven by the rotation of the main bit.
A method of drilling using a directional drilling system as claimed in any of the preceding claims, the method comprising the steps of using the pilot bit to form a pilot bore, using the main bit to form a main bore, and adjusting the position of the pilot bit axis relative to the main bit axis to control the position of the pilot bore relative to the main bore.
Dependencies are inferred from the claim text.