초록 ▼

Apparatus and methods for drilling subterranean formations with a rotary-type drill bit are disclosed in which oscillation is produced in the drill string, drill bit or cutting element, in an axial and/or torsional direction, to produce formation chips that have both thin portions and thick portions

Apparatus and methods for drilling subterranean formations with a rotary-type drill bit are disclosed in which oscillation is produced in the drill string, drill bit or cutting element, in an axial and/or torsional direction, to produce formation chips that have both thin portions and thick portions. More specifically, the oscillations cause a cutting element of the drill bit to engage the formation to various degrees, resulting in a chip that has varying thicknesses which facilitate fracture of the chip along its thinner portions, thereby reducing the likelihood of adherence of the formation chips to the drill bit or cutting element.

대표청구항 ▼

1. An earth drilling device for variably contacting an earth formation, comprising:a near bit sub member configured for attachment to the downhole end of a drill string; a bit body attached to said near-bit sub member, said bit body having fixed cutting elements secured thereto and positioned to con

1. An earth drilling device for variably contacting an earth formation, comprising:a near bit sub member configured for attachment to the downhole end of a drill string; a bit body attached to said near-bit sub member, said bit body having fixed cutting elements secured thereto and positioned to contact an earth formation; and apparatus associated with said near-bit sub member for producing a variable depth of cut by said fixed cutting elements into said earth formation while said bit body is rotated by said drill string and wherein said apparatus is structured to provide axial movement of said bit body relative to said near-bit sub member to produce a variable depth of cut by said fixed cutting elements into said earth formation during drilling, said apparatus comprising a lower member attached to said bit body and an upper member spaced from said lower member and biased with respect thereto by a resilient member providing movement of said lower member relative to said upper member.