While planning an Angsi field development well offshore Malaysia, directional casing while drilling (DCwD) was identified as an enabling technology for reducing operation time and well construction costs. On offset wells, DCwD had improved top hole drilling performance by providing superior hole cleaning combined with higher annular velocities thereby increasing ROP.
Well Angsi-D12 would be drilled from 26" conductor with 13–3/8" casing with the following BHA: 12¼" mill tooth bit, 17½" single row under-reamer, PDM, ABH and GWD/MWD. The use of DCwD would also solve any hole cleaning issues due to the small annulus created by the 13–3/8" × 17½" BHA and allow faster penetration rates to be used. The well was planned to be built-up to 70° inclination whilst drilling from 186m MD to TD at 1680m MD.
Project objectives were to:
enhance the safety and efficiency of top hole drilling by eliminating the casing running operation;
apply gyro-MWD to survey during the magnetic interference area (186m MD to 418m MD) then switch to standard MWD to survey thereafter;
casing drill from the 26" conductor shoe to TD in one run.
The 13–3/8" DCwD operation was successfully completed from 26" conductor to TD on well D12 without rig modification using a standard casing drive system. The DCwD application produced a high average on-bottom penetration rate of 87.3m/hr with instantaneous ROP reaching 450m/hr. The system produced good control of DLS whilst sliding and easily transferred weight to the bit at 70° inclination at 1500m to TD at 1525m. Close cooperation between the operator and service provider led to two new 13–3/8" DCwD records, one for the longest section drilled and another for highest inclination. The new benchmarks will enable the operator to deploy cost cutting DCwD technology in more challenging projects in eastern Malaysia. The authors will discuss application challenges, well planning/implementation in addition to economic and operational results.
