On the Need to Take Into Account Vibrations when Designing the Elements of the Drill String

Abstract

Uneven rotation of the bottom hole drill stem assembly (BHA) and the drill string is a source of torsion shocks that create high-frequency and high-amplitude vibration. A correlation between torsional and lateral vibrations is discovered. An analysis demonstrates that an increased vibration load on the drill string and the bottom hole drill stem assembly leads to a decrease in the mechanical on-bottom drilling rate and premature wear of equipment. A suitable selection of all the elements of BHA that takes into account the possibility that different types of vibrations may arise and an adjustment of the drilling parameters (bit load, rotational speed) together lead to an increase in the drilling rate, the reliability of the drilling equipment, and a decrease in the time needed to construct the well. Real-time monitoring for shocks, vibrations, and stick-slip will help to increase the precision of estimates of the state of downhole equipment.