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

Abstract

The article is devoted to the study of dynamic phenomena in the drill string based on energy positions. The
friction of mechanical transmissions in rotor drive, curved sections of the drill string on drill-hole walls in the
drilling mud and change in the torque on the bit are the main causes of the mechanical energy consumption in the process of drilling. In this case, the required engine power is used for to provide drill string rotation in the well with some unevenness and bottom-hole deepening. 

The power balance equation of the mechanical system “power drive–drill string–bottom hole” is analyzed. The
authors have developed the problem for defining the kinetic energy of drill string in rotor drilling, which is spent on overcoming the friction in drive transmissions and drill string on drill-hole walls in the drilling mud as well as on drilling the bottom hole. The use of the defined mathematical dependencies is demonstrated by the nomograph for determining the friction power in case of drill string free run in the well. The obtained results of theoretical research can be used by engineering and manufacturing divisions of drilling enterprises for the engineering estimate of energy consumption in rotary drilling.