Curing stick-slip: Eureka.

Abstract

Abstract This work investigates the results of the first deployment in the industry of technology Z on an offshore drilling rig with a heavy top drive. The study uses a quantitative analysis of downhole data to confirm the benefits of Z. Z expands the stick-slip free operating envelope and does not require tuning. Following a dozen or so Z land rig deployments since 2015, the technology was added to a heavy offshore rig, a newbuilt, with modern hi-end variable frequency drives that enable near-zero control loop latencies. A study validates the effectiveness of the system with downhole rotary speed data. The Z system was used for multiple sections in the Barents Sea, where the overburden traditionally causes troublesome torsional vibrations. The users of the technology gave a positive feedback from their first experiences. This work aims to verify qualitative surface observations with a quantitative analysis of downhole data. Downhole sensors captured the dynamics of multiple locations in the drill string over the course of about 3 weeks. Stick-slip severity was quantified using downhole rotary speed data. Periods when Z was turned on were compared to periods when Z was turned off.