Specific features of drilling mode with extendable working elements

Abstract

The work is devoted to the calculation of the main technological parameters of a bit of a new patented design, the essence of which is to replace worn out working elements (carbide cutters or diamond-containing matrices) during drilling with a new, not blunt tool right at the bottom of the well. The need to correct the calculation method is associated with the design feature of the new crown, which consists in the fact that when using it, an annular bottom of a larger width is formed compared to serial crowns of the same outer diameter. Therefore, the known formulas for carbide and diamond drilling have been supplemented with appropriate correction values so that the ROPs when using new and serial bits are the same during full development. So, when using carbide cutters as rock-cutting elements, a correction factor is introduced that increases the number of main cutters in the crown sectors of the first and second stages. In diamond cutting, it is necessary to increase the maximum speed of the tool, taking into account the mining technical conditions of penetration. Refined formulas for calculating the parameters of the drilling mode allow preserving the advantages of bits with extendable working elements and increasing the drilling speed by 1.7-1.8 times compared to existing serial bits.