An operator wanted to find a suitable system to reliably drill a HPHT well from a semisubmersible rig in the North Sea. While the full managed pressure drilling (MPD) system was previously used, the expertise required from the rig crew and the cost of the system influenced the operator to look for alternative technologies to detect fluid gains and losses in this challenging drilling environment.
The recommended FLAGHD™ fluid loss and gain detection service was implemented to provide a faster response and accurate flowmetering to minimize invisible lost time and optimize lost circulation material (LCM).
The SLB team executed the installation of the 12-in Coriolis flowmeter, including rig survey, design preparation, and strategic planning. After the installation, a range of tests were completed on the system to verify the integrity of the installation and that the bypass valves were able to change flow direction between the main and bypass flowline.
SLB worked with the rig crew to establish procedures to clean the Coriolis sensor and control the bypass valves. The SLB team also explained the calibration steps for each drilling section to provide an accurate threshold of detection. Warning and critical thresholds are automatically generated after the calibrations and proposed for validation. The system compares the theoretical return flow versus the actual flow coming from the Coriolis sensor in real time. Through this comparison, FLAGHD service can detect and alert of any influx or loss. Having such monitoring of flow return versus mud pit evolution provides a faster detection of kick or loss from downhole without being affected by surface events, such as mud transfer or additional chemicals in the active system.
The implementation of FLAGHD service significantly boosted efficiency by delivering an outflow signature within minutes compared with the conventional flow check method that typically demands 10–15 minutes per pump stop. This improvement not only expedited rig processes but also provided the operator confidence to proceed with drilling the planned HPHT well in reliable conditions.
