The percussion performance drilling motor was proposed in combination with polycrystalline diamond cutter (PDC) drill bits to overcome the drilling challenges of the 12 ¼ in. vertical section in Ahnet field (South-West of Algeria), consisting of harsh lithology types habitually drilled using several bits run.
Introducing the percussion drilling motor is the next step for performance optimization in harsh drilling environments. Utilizing the advanced generation of performance elastomers in combination with new energy distribution system enhances the drill bit's rock failing mechanism by combining the torque and rotation speed with a high frequency axial oscillation. This lifts the entire BHA with each pulse while maintaining the drill bit always fully embedded into the formation, resulting in an increased penetration rate. This paper presents a case study that evidences the benefit of using such a tool to reduce the drilling cost.
The 12 ¼ in. section in the subject field is usually drilled using 6-10 drill bits with the associated excessive non-productive time (NPT) and increased drilling costs for the operator. Extreme dull characteristics are also exhibited by all drill bits after every run. The introduction of the percussion drilling motor in this section represents a step change in performance and drilling efficiency to reduce drilling time. In combination with optimized PDC drill bits, the percussion drilling motor completed the interval with just 2 bits compared to offsets using 10, 8, and 6 bits, respectively. In conclusion, this approach crucially contributed to save 7.72 drilling days to the client compared to the initial plan. Moreover, an increase of 119% was recorded in term of ROP compared to the best offset well and a very good hole quality with only 0.7% excess recorded on the caliper log.
The innovation of the percussion performance drilling motor is a completely new telescopic bearing mandrel design to keep the drill bit always in contact with the formation while gently oscillating the upper BHA reducing friction, improving weight transfer, and improving bit cutting structure efficiency enhancing its rock-failing properties.