Review on dynamic models of drilling systems applied in oil and gas industry.

This is a review on models for dynamic analyses of various drilling systems suitable for application in oil and gas industry. The rotary and also rotary–percussive drilling systems, vertical, horizontal and inclined, are physically and mathematically modeled. The basic physical model for analysis of the drilling system is the Timoshenko beam. Torsional, axial, transversal and combined vibrations of the drill string are considered. Special attention is given to bit–rock interaction models. Various mathematical expressions for bit–rock torque and force are suggested. Inclusion of these mathematical models in the drilling system consideration is expected in the future. In the paper advantages and disadvantages of drilling systems are also discussed. Finally, the aim of this review is to give direction for future research and improvement in drilling systems. [ABSTRACT FROM AUTHOR]