High Performance Coil Tubing Drilling in Shallow North Slope Heavy Oil

Abstract

Abstract Coil tubing drilling (CTD) completed a very successful 4 well pilot project that drilled lengthy horizontal multi-laterals into shallow heavy oil reserves at the Milne Point field on Alaska's North Slope. The CTD sidetracks were drilled with the proper combination of tools that delivered good incremental oil production rate at low cost. This was a new field for the CTD team with challenging directional and completion issues. A coiled tubing electric line drilling BHA and innovative completion techniques were required to achieve objectives. Three dual-lateral wells and one single-lateral well were drilled into thin shallow sands and completed using slotted liner and flow-through whipstocks. Sensors in the modular electric-line CTD bottom-hole-assembly communicated to the surface with an electric line umbilical that provided extremely high-speed directional information, real time downhole weight on bit (DWOB), resistivity data, gamma-ray data, internal pressure and annular pressure data. The electric line also provided power to accurately drive a downhole electric orienter. These features combined with high performance PDM motors achieved very high penetration rates with 3.75 inch PDC bits. Several North Slope CTD drilling records were set during the project. Liner running from high departure parent wellbores proved to be quite challenging but ultimately successful. Learning and performance improvements were made as the project progressed. This paper will review the performance of the CTD BHAs and the completion innovations applied in this project.