A Multi-Faceted Approach for Mitigating High Frequency Torsional Oscillation for Motorized Rotary Steerable System Bottom Hole Assemblies

Abstract The paper describes a systematic approach for mitigating High Frequency Torsional Oscillation vibration (HFTO) for a motorized rotary steerable system (RSS) through bottom hole assembly design (BHA), drill bit design and real time mitigation technology and processes. There have been various HFTO mitigation tools in the market utilized to mitigate HFTO however these tools may not fully complement the efforts if the system design is not optimal for the application. The various production section motorized RSS BHA design configurations in the Permian Basin and design considerations to reduce HFTO vibration will be discussed in the paper. A methodology for comparing BHA stiffness models with HFTO vibration will be illustrated. HFTO vibration measurement methodology and effectiveness in real time is critical to apply mitigation strategies to reduce the HFTO vibration severity to prevent down hole tool failures. Bit design features should balance rate of penetration (ROP) performance while ensuring drill bit stability and efficiency for the planned application. Real time mitigation strategies are a critical step to a lower HFTO vibration severity signature. The RSS tool measures HFTO at 1 kHz sampling rate and processes and records the mode frequencies and their magnitudes continuously and reports to surface in real time whenever high HFTO magnitude is encountered, making it possible to mitigate HFTO in real time. Field data has shown proper optimal stiffness configurations of the BHA components can effectively reduce the likelihood of certain damaging modes of HFTO from happening. Different drill bit designs and cutter technology were also tested and their effects on HFTO mitigation is analyzed. Real time operational mitigation of HFTO has been proven effective in most cases whereas in other cases the HFTO damage occurs too quick to mitigate. A few case studies are presented to show the effects on HFTO mitigation by combining BHA design, drill bit design, drilling parameter adjustment as well as downhole tool design. The paper also illustrates cases while utilizing different types of vibration mitigation tools in the BHA's however its effectiveness to mitigate high severity HFTO may be inconclusive on many situations because of other predominant suboptimal factors in BHA design, drill bit design and drilling practices. The paper describes the planning and execution approach for applications with motorized RSS systems to minimize HFTO vibration related downhole tool failures and improve drilling performance. The different combination of technologies utilized to mitigate HFTO should continue to be analyzed. However, the variability in results may be because of several factors that need to be scrutinized further to derive consistent results. A multi-faceted planning and execution approach is essential to mitigate HFTO for drilling performance.