Patent ID: 7059431

Claim:
Auto-penetrating drilling method for well drilling in rock; using a drilling tool rotating around an axis, said method comprises generating, by the rotation of the drilling tool, of a thrust parallel to the direction of said axis and oriented in a heading direction of the tool in the rock, wherein: the thrust on the drilling tool is generated by the reaction of the rock on the drilling tool during the mechanical cutting of the rock by the drilling tool and; said tool is composed of N blades numbered from 1 to N in the opposite direction to a rotation direction; each blade being arranged in a spiral around the axis of the tool and on a slant with the tool axis; the part of the blade closest to the tool nose is also the closest to the tool nose axis; each blade is mounted with k drill cutters; the first drill cutter is the cutter closest to the axis and the tool nose; each drill cutter is identified with two index references; the first index reference n, variant between 1 and N, corresponds to the number of the blade on which the drill cutter in question is mounted, the second index reference k, variant between 1 and K, corresponds to a position of the drill cutter in question on the blade starting from the first drill cutter, in this way the k-th drill cutter of the n-th blade is identified as drill cutter T(n,k); each drill cutter has a face, hereafter referred to as driving face that makes contact with the rock; this method is such that, to generate a thrust in the heading direction of the tool, the geometries, positions, and orientations of all or part of the said drill cutters are calculated respecting the following rules; the k-th drill cutter of the last blade T(N,k) cuts a groove in the rock at a previous revolution R(g−1) of the tool downstream of the groove cut by the (k+1)th drill cutter on the first blade, T(1,k+1) at a current rotation R(g) of the tool; the k-th drill cutter of the n-th blade, T(n,k) cuts a groove into the rock at a current revolution R(g−1) of the tool downstream of the groove cut by the k-th drill cutter of the (n+1)th blade, T(n+1,k), at the current rotation R(g) of the tool; a perpendicular to the drill cutter driving face has a component according to the rotation axis in the upstream direction.