INFLUENCE OF TORSIONAL AND LONGITUDINAL VIBRATIONS ON DRILLING SPEED AND FORMATION OF BREAKDOWNS OF CUTTING ELEMENTS OF PDC-REINFORCED DRILL BITS

The relevance. Currently, for construction of oil and gas wells, the most effective tool are bits reinforced with PDC (polycrystalline diamond cutters). These bits work on cutting–chipping principle, as the cutting is the most effective among all the mechanisms of rock destruction, due to the fact that the tensile strength of the rock and chipping is much less than its compressive strength. The analysis of the state of spent drill bits reinforced with PDC plates shows that they work out their life not fully, as a part of the cutting PDC elements fails due to chipping. The variety of forms of chips in shape and size requires classification, identification of the reasons of occurrence and determination of loads that lead to their occurrence. In addition, the scrapping of plates or their loss significantly affects the final technical and economic performance of drilling exploration and production wells. Solving the issues of improving the quality of bits by reducing the number of breakdowns will help to improve the economic efficiency of work in extraction and exploration of minerals. The aim of the study is the sizing platform chips for possible classification depending on the thickness of the shear layer of rock cutting element, and determining the causes of torsional and longitudinal vibrations in the drill string, causing breakage of the PDC offered a constructive change of drill bits reinforced PDC plates, warning the appearance of self-oscillations in the drill string. Objects: cutting elements of drill bits reinforced with PDC plates with a flat front face and PDC with a convex front face, chips of PDC plates on drill bits arising during drilling. Methods: experimental and analytical method of research on laboratory samples and on spent drill bits reinforced with PDC plates. Result. Based on the analysis and generalization of the results of the laboratory studies of the PDC plate breakdown occurrence causes and their nature the authors have developed the number of technical and technological solutions that prevent the occurrence of torsional and longitudinal self-oscillations in the drill string, and increase the efficiency of rock-cutting tools reinforced with PDC plates.