Double-stage drill bit

Abstract

The invention discloses a double-stage drill bit which comprises a pilot hole body (1) and a reaming body (2). The pilot hole body (1) is fixedly arranged above the reaming body (2). The maximum outer diameter of the pilot hole body (1) is smaller than the maximum outer diameter of the reaming body (2). A plurality of first cutting units (3) are arranged on the pilot hole body (1). The reaming body (2) is provided with a plurality of second cutting units (4). Cutting teeth (5) are distributed on the first cutting units (3) and the second cutting units (4). A first chip removing groove (6) is formed between every two adjacent first cutting units (3). A second chip removing groove (7) is formed between every two adjacent second cutting units (4). A pilot hole nozzle (8) is arranged on each first chip removing groove (6). A reaming nozzle (9) is arranged on each second chip removing groove (7). The double-stage drill bit is reasonable in design and suitable for drilling operation of the hard stratums, the upper part and the lower part act on well wall rock stratums together, and the penetrating ability of the drill bit and grinding resistant performance of an outer cone are outstanding.

Description

technical field [0001] The invention relates to the field of geological exploration drilling tools, in particular to a two-stage drill bit suitable for drilling in hard formations and extremely hard formations. Background technique [0002] PDC bit is a drilling tool commonly used in the oil drilling industry. However, it cannot be used in heterogeneous hard formations for the following reasons: first, it is difficult for the PDC bit to penetrate into the formation in heterogeneous hard formations; Fast; third, due to the strong heterogeneity and high hardness, the torque of the PDC drill bit is too large when breaking rocks, the drill bit vibrates seriously in the axial and lateral directions at the bottom of the well, the cutting teeth are seriously damaged by irregularities, and the cutting teeth are seriously cracked. The design of the existing PDC drill bit is unreasonable, there are defects, and various performances cannot be taken into account, so it cannot be used. ...

AI Technical Summary

Problems solved by technology

However, it cannot be used in heterogeneous hard formations for the following reasons: first, it is difficult for the PDC bit to penetrate into the formation in heterogeneous hard formations; Fast; third, due to the strong heterogeneity and high hardness, the torque of the PDC bit is too large when breaking rocks, the bit vibrates severely in t

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