Abstract
Conventional PDM (Positive Displacement Motors) are widely used in coiled tubing drilling jobs. PDC bits are often used with the PDM’s because of their longer life, increased ROP, and increased steerability. But conventional PDM-PDC bit systems often create hole problems and high vibrations that result in casing running problems, downhole equipment failure and lost drilling time.
A new steerable assembly has been designed that provides significant advantages over conventional steerable assemblies. The new system comprises of uniquely designed pin-down mud motor with a specially designed long-gauge PDC bit in a matched drilling system. To date, field results from the new system have shown to improve hole quality and increase ROP. Other advantages include less hole spiraling and tortuosity, reduced vibration, better steerability and hole cleaning, increased bit life, and improved PDM and MWD reliability. These benefits are expected to have considerable implications for coiled tubing drilling applications.
