WorldOil

Technology from Europe: Anti-stall tool reduces destructive vibrations in simultaneous drilling, under-reaming operation

The combination of under-reamer technology with rotary steerable systems allows simultaneous drilling and under-reaming but also adds a significant challenge in terms of predicting bottomhole assembly stability. The arrangement of PDC cutters at different levels and the limited number of blades on the under-reamer increase the likelihood of vibration, as the two different levels of cutters might be working in two different layers of rock at the same time. This increased vibration raises the risk of downhole tool failures and costly round trips. In addition, the coupling of instabilities between the sets of cutters can produce an overall reduction in drilling efficiency that adds cost through reduced progress with the under-reamer.