TWO-TIER DRILLING BIT FOR CORE SAMPLING Russian patent published in 2024 - IPC E21B10/43 

FIELD: well drilling.

SUBSTANCE: two-tier drilling bit for core sampling includes a lower drilling tier with a stabilizer and an upper drilling tier with a stabilizer, the lower tier of the bit is made in the form of a detachable drilling head. Bit is made with possibility of connection via shank with core set. Each blade of the drilling head on the side of the face has a horizontal surface. Between the horizontal surface and the leading edge of each blade of the drilling head there is at least one pair of protruding PDC inserts. Each PDC insert of the above pair has the same negative cutting angle. First PDC insert located closer to the bit axis has lateral cutting angle a_1. Second PDC insert has a lateral cutting angle a₂. Lateral cutting angles a₁ and a₂ have opposite directions so that shanks of said pair of protruding PDC inserts are removed at a greater distance than their cutting surfaces. Value of said lateral cutting angles a₁ and a₂ is selected such that when said pair of protruding PDC inserts are introduced into the rock, adjacent surfaces of the furrows are formed, wherein the furrow surface formed by the second PDC insert is flatter than the adjacent furrow surface formed by the first PDC insert.

EFFECT: increasing the accuracy of bit stabilization by eliminating the drift of its drilling head from the longitudinal axis of the bit.

2 cl, 5 dwg