First Deployments of Friction Adjustable Stabilizer Technology in the GCC

Abstract

The paper seeks to address the challenges of drilling BHA dysfunction which impacted the drilling performance in Abu Dhabi Offshore. Drilling operations experience vibration and stick-slip which limited the ROP and often led to BHA failure cases. In addition, challenging trip out and casing running were observed which indicated unsatisfactory borehole quality. Enhancement of the drilling BHA is required to reduce vibration and improve borehole quality. In reference to study of Self-Excited Stick-Slip Oscillations of Drag Bits by Thomas Richard in 2001, reducing the amplitude of the vertical oscillations should lessen (if not eliminate) the severity of the coupling between the two modes of vibrations, and therefore, of the self-excited vibrations. This could be achieved by minimizing the upward motion of the BHA, by appropriately increasing the lateral friction between the BHA and the borehole wall. Appropriately means "without affecting too strongly the overall efficiency of the system." Friction Adjustable Stabiliser Technology (FAST) is designed with patented features to achieve the above-mentioned BHA condition. A series of runs with FAST incorporated into RSS drilling BHA were planned. A set of KPIs were put in place to evaluate BHA performance. The drilling BHA was simulated to obtain the optimum tool placement, in collaboration with BHA providers. The drilling results were then analysed and compared with analogue wells to demonstrate the deployment of this technology. The deployment of FAST was conducted in 12-¼″ and 6″ hole sections with a total of 7 runs. FAST was run with various RSS systems with low level of vibration in the majority of the runs and proven to minimize vibration/stick-slip during drilling by acting as the BHA contact point and delivering consistent and sufficient friction. As a result, the drilling BHAs were able to deliver the objective to TD and avoid additional trips due to BHA failure. Borehole quality was evaluated through trip out BHA and casing/tubing RIH performance. There is still room for improvement in trip out performance, as backreaming was still required in most of the runs. However, positive impact to performance of RIH casing or lower completion from good quality borehole drilled by BHA with FAST was confirmed from all runs. The saving from fit-for-purpose BHA design on average is 2 days, considering the average NPT for trip out the BHA. In addition, improvement in trip out performance in 6″ section is 0.4 days. Considering above, total saving from 6″ section is 2.4 rig days. The detailed BHA performance analysis and operation feedback from subsequent wells will be beneficial to assess the suitability of this technology to overcome future drilling challenges.