Abstract
High-frequency measurements can provide much more new insights for drillstring dynamics compared to traditional instruments, leading to a new realm of understanding of drillstring behaviors in great detail than before. In this paper, data acquisition tools with high-frequency sample rates and the data processing are introduced. Based on high-frequency data, progress of drilling dynamics is summarized, including new understandings of low-frequency drillstring dynamics, high-frequency torsional oscillations (HFTOs), and high-frequency axial oscillations (HFAOs) and new findings for the coupling of vibrations and motions, as well as models and simulation methods to deeply comprehend high-frequency dynamics of drillstring. High-frequency measurements have been used for enabling drillers to improve drill performance, especially for field decision making, BHA selection, and bit design, usually through the ways of minimizing vibrations to obtain high-efficient drilling conditions, the high-frequency response near bit can also be used for lithology identification during drilling. Though there still exists a gap between research perspective and drilling practice, the industry of high-frequency measurements has gotten off a good start, which has huge potential to avoid nonproductive time thereupon reducing drilling cost in the future.
Highlights
High-frequency measurements can provide much more new insights for drillstring dynamics compared to traditional instruments, leading to a new realm of understanding of drillstring behaviors in great detail than before
High-frequency measurements have been used for enabling drillers to improve drill performance, especially for field decision making, bottom-hole assembly (BHA) selection, and bit design, usually through the ways of minimizing vibrations to obtain high-efficient drilling conditions, the highfrequency response near bit can be used for lithology identification during drilling. ough there still exists a gap between research perspective and drilling practice, the industry of high-frequency measurements has gotten off a good start, which has huge potential to avoid nonproductive time thereupon reducing drilling cost in the future
Via equation (3), the linearized vibration amplitude along the BHA could be calculated based on an assumed fluid-damping model and a specific harmonic excitation. e calculate accuracy of this model was verified by high-frequency field downhole data, the average error of calculated lateral natural frequencies (
Summary
Traditional vibration or shock detecting is based on measurement while drilling (MWD) devices and surface monitor instruments, by which the phenomenon with low frequency, such as stick-slip, and transverse or longitudinal vibrations, whirl, are observed. E advanced tool such as vibration MWD tool is a wellestablished industry standard MWD tool (with up to 1000 Hz at a sampling rate of 2500 Hz, 200 g sensors for each axis, 4 GB memory) for downhole dynamics and drilling optimization, and it is located above the rotary steerable system and owns the ability of transferring averaged data to surface in real-time and storing raw data in memory for post-well analysis. E data measured provided critical information to understand tool response characteristics under different drilling parameters, inclinations, and conditions By these data, better understanding of basic vibration modes is obtained, some new phenomena such as HFAO and HFTO are discovered, and the studies of complex coupling between different oscillations of drillstring have made a great progress
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