Abstract
In an extended-reach and horizontal well drilling environment, stick-slip becomes increasingly problematic with smaller-diameter and longer drillstring. Surface detection of the bottom-hole assembly stick-slip and vibration becomes ever more difficult. A Real-time Stick-slip and Vibration Detection (RSVD) system was incorporated into a rotary-steerable system (RSS), to increase drilling efficiency in deep wells and to protect the RSS and the MWD/LWD tools from harmful vibrations. Bit/BHA instability often results in excessive vibration and stick-slip problems, which lead to BHA component failure, poor directional results and excessive wear/damage to bits.
This system is a unique near-bit vibration sensor integrated into the RSS, featuring detection of the three principal modes of drillstring vibration: torsional, lateral and axial. The sensor system sends the detected stick-slip severity to the surface in real time so that operators can change drilling parameters if harmful downhole conditions are detected. Additionally the real-time drilling data were remotely available to a multi-disciplinary drilling optimization team consisting of engineers and researchers.
This sensor system has been extensively tested and proved to be effective with the 8 ½-in.-hole-size RSS in various wells, including vertical and horizontal, both onshore and offshore. This paper reviews the harmful stick-slip and vibration conditions in smaller-hole-size wells and how the RSVD system improved penetration rate and prolonged the optimum performance of the drill bit, bottom-hole assembly (BHA), MWD/LWD, and RSS in various situations.
Through the integrated sensor and team approach, the ability to detect poor borehole conditions and/or BHA instability due to vibration allows RSS operators to take timely remedial action before downhole RSS failure occurs. As a result, the performance and survivability of the RSS has been remarkably improved.
