Swell solution
March 1st 2008

Drilling in choppy seas is fraught with hazards. As the sea swells relative to the drilling platform, the stresses and strains induced on a drill pipe will alternately take the weight of the ship or try to pull itself out of the seabed.

A new servo hydraulic protection system from Moog provides an intelligent 'flow fuse' that not only automatically resets, but regulates the platform speed in the event of an exceptional wave and brings the platform to a controlled stop in the event of a drill break.

The system works by pre-charging an accumulator to a pressure sufficient to hold the drill weight. As the platform moves up and down with the heave of the sea surface, hydraulic oil passes backwards and forwards from actuator to accumulator, keeping the platform stationary relative to the seabed. Each actuator has a position sensor which enables the Moog MSC Controller (M3000) to monitor the position and velocity of the platform. Two Moog DSHRE 80 servo cartridge valves regulate the flow of the hydraulic oil with capability to flow 6100L/min and to open or close in 18 milliseconds.

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