Estimation of mechanical energy consumption of the drill string in rotary drilling

The article is devoted to the study of dynamic phenomena in the drill string based on energy positions. Thefriction of mechanical transmissions in rotor drive, curved sections of the drill string on drill-hole walls in thedrilling mud and change in the torque on the bit are the main causes of the mechanical energy consumption in theprocess of drilling. In this case, the required engine power is used for to provide drill string rotation in the well withsome unevenness and bottom-hole deepening. The power balance equation of the mechanical system “power drive–drill string–bottom hole” is analyzed. Theauthors have developed the problem for defining the kinetic energy of drill string in rotor drilling, which is spent onovercoming the friction in drive transmissions and drill string on drill-hole walls in the drilling mud as well as ondrilling the bottom hole. The use of the defined mathematical dependencies is demonstrated by the nomograph fordetermining the friction power in case of drill string free run in the well. The obtained results of theoreticalresearch can be used by engineering and manufacturing divisions of drilling enterprises for the engineeringestimate of energy consumption in rotary drilling.