An operator in Brazil wanted to drill a 12¼-in section from an offshore fixed platform. The well plan specified a 3D trajectory of 2°/30-m dogleg severity (DLS) for almost 1,500 m. Previous wells from this platform were drilled by directional drillers in manual mode, sending downlinks from the surface to change the steering ratio and toolface on demand to follow the proposed well trajectory. This field test assessed the autonomous downhole control system’s ability to navigate the curve.
The PowerDrive Xcel™ RSS was recommended for a single run bottomhole assembly (BHA) because the auto-curve mode adjusts the steering ratio automatically based on required DLS and toolface.
Auto-curve mode was engaged once the BHA was out of the casing shoe at 10° inclination. The directional drillers varied the DLS and toolface as necessary, which were the only two inputs needed to drill to total depth (TD). Using auto-curve mode reduced the number of downlink commands by 33% from drilling in manual mode.
The autonomous downhole control system accounted for the influences of drilling parameters and formation characteristics on the trajectory response. The PowerDrive Xcel RSS reacted quickly to the changes compared with manual drilling. Thus, the drilled well path was closer to the planned wellbore path, and the risks associated with directional drilling uncertainties were minimized. Both the operator and the directional drillers provided positive feedback on auto-curve’s performance.
Using the autonomous downhole control system enabled the operator to improve net ROP by 38%, beating the perfect well net ROP by 10%. Additionally, total drilling time was reduced by 25 hours compared with the budgeted well time and 17 hours compared with the perfect well time for this field.
| Key Performance Indicator in 12¼-in Section | Perfect Well Time | Budgeted Well Time | PowerDrive Xcel RSS Time |
| Total drilling time, h | 61 | 69.15 | 44.5 |
| Net ROP, m/h | 45 | na | 49.6 |
PowerDrive Xcel RSS with auto-curve improved drilling efficiency for the operator by increasing ROP, reducing downlink commands, and decreasing total drilling time.
