Historic performance in slim hole rotary steerable (RS) applications in the Middle East was held back by severe torsional and lateral vibration issues. A new family of slim hole polycrystalline diamond compact (PDC) bit designs, specifically matched to the rotary steerable systems (RSS) used, has resulted in a dramatic improvement in performance.

The use of mathematically modeled bit performance indices has resulted in a significant improvement in RSS and bit performance while drilling harsh environments in the Middle East where lateral and torsional vibration events are severe. The bit design in question was further optimized by including design characteristics specifically targeted at reducing torsional events. Further, bit hydraulics have been optimized to minimize erosion and maximize borehole quality while matching system operation requirements.

Case studies are presented clearly demonstrating runs with superior performance in the Kingdom of Saudi Arabia (KSA). The field trials clearly demonstrated that significant reduction in torsional vibration and improved side cutting led to superior dogleg achievement. Improvement in lateral stability and resultant bore hole quality led to extended bit and tool life, thus notably improving penetration rate.

The paper concludes that significant performance increases can be achieved by matching the bit design to the RSS, the well geology and the well trajectory. This has resulted in advances in slim hole drilling.

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