DUBAI, UAE – GEOLOG has introduced a rig measurement system to assist offshore well control.
According to the company, advanced flow meters are often installed on the mud return line to closely monitor drilling fluid in order to improve early kick detection capability.
On floating drilling rigs, however, heave movement affects the accuracy of critical return flow measurements. The heave effect leads to movement of the telescopic joint into the riser, displacing the drilling mud into the returns flowline.
These movements introduce variations in return flow that mask the true flow responses from the well, the company adds.
Its solution is an accelerometer, located at the center of gravity of the installation, continuously measuring the rig’s movement under the heave combined with a predictive algorithm.
The latter computes and compensates the flow variations induced by the telescopic joint’s ‘pump’ effect.
A self-tuning feature is designed to adapt to changes in heave height and period in real time, with no additional operator input needed.
According to GEOLOG, various major operators have used the system for deepwater drilling offshore West Africa, with one operator expanding its use to deepwater European/CIS operations.
The system is tuned and once the predictive system’s operating parameters have been acquired, GEOLOG says it can detect and measure the flow-out component caused by the rig’s heave movement in real time.
It then eliminates this from the flow-out measurement - already normalized for drill pipe displacement and changes in circulating parameters - to derive a true ‘Heave Compensated Flow-out’ measurement.
The system continues the tuning process, adapting to changes in heave height and period in real-time, facilitating detection of kicks and losses on floating rigs, and ruling out false alarms resulting from heave motion.