US 5,507,357 A · Pilot bit for use in auger bit assembly

Abstract

A pilot bit for use with an auger bit in an auger bit assembly secured to the downhole end of tubular drill stem for drilling boreholes in earth formations comprises a tubular pilot bit body having a downhole end and an upper end at the axially opposite end of the body, the body being dimensioned to be telescopically received within an axial bore of an auger bit and being releasably connectable to the auger bit against axial and angular displacement, an axial throughbore extending through the body for telescopically receiving an earth sampling tool, a closure device secured to the downhole end of the pilot bit for opening and closing the throughbore, and pilot bit cutting teeth secured to the closure device. The closure device is movable between an open position removed from the throughbore to permit passage of a sampling tool through the pilot bit into an earth formation and a closed position whereat the closure device seals the throughbore and the pilot bit cutting teeth are disposed for cutting into an earth formation upon rotation of the pilot bit.

Claims13

Dependent claims

A pilot bit for use with an auger in an auger bit assembly secured to the downhole end of tubular drill stem for drilling boreholes in earth formations, said pilot bit comprising:

a tubular pilot bit body having a downhole end and an upper end at the axially opposite end of said body, said body being dimensioned to be telescopically received within an axial bore of an auger bit and being releasably connectable to said auger bit against axial and angular displacement;
a axial throughbore extending through said body for telescopically receiving an earth sampling tool;
and
closure means secured to said downhole end of said pilot bit for opening and closing the downhole end of said throughbore, pilot bit cutting teeth secured to said closure means, said closure means being movable between an open position removed from said throughbore to permit passage of a sampling tool through said pilot bit into an earth formation and a closed position whereat said closure means closes said downhole end of said throughbore and said pilot bit cutting teeth are disposed for cutting into an earth formation upon rotation of said pilot bit.

1 more element

An auger bit assembly for use in drilling boreholes in earth formations, said assembly comprising, in combination:

an auger bit having a tubular body having a downhole end and an upper end remote said downhole end, auger means on the outer side of said auger body for longitudinally conveying cuttings upwardly of a borehole hole, an axial passageway extending through said auger body, cutting teeth at said downhole end of said auger body for cutting an annular hole upon rotation of said auger bit, and means for securing said auger bit to a drill stem for rotation therewith;
and
a pilot bit having a tubular body having a downhole end and an upper end remote from said downhole end and dimensioned to be telescopically received in said auger bit axial passageway in sliding fit relation, a throughbore extending axially through said pilot bit body for telescopically receiving an earth sampling tool, closure means secured to said downhole end of said pilot bit for opening and closing said throughbore, pilot bit cutting teeth secured to said closure means, said closure means being movable between a closed position whereat said closure means closes the downhole end of said throughbore and said pilot bit cutting teeth are disposed for cutting into an earth formation upon rotation of said pilot bit and an open position removed from said throughbore to permit passage of a sampling tool through said pilot bit into an earth formation.

Dependencies are inferred from the claim text.

Pilot bit for use in auger bit assembly

Life of this patent

Pilot bit for use in auger bit assembly

Life of this patent

Abstract

Claims13