Given the two red flags that had been thrown up previously, one would have expected that as a precaution a cement plug would have been placed somewhere in the wellbore as a secondary pressure seal before this primary pressurecontrolsystem (heavy mud) was evacuated from the wellbore.
At 8:20 p.m. on the day of the explosion the pressure data suggest there was a constant flow of sea water being pumped into the drill pipe that was displacing the heavier mud system which was the primary pressurecontrol for the well.
Using a force controlsystem reacting to the pressure on the feet, HyQ can navigate and traverse irregular surfaces and adjust its pace to overcome obstacles of different sizes and shapes.