MeBo drill rig description

The central parts of the drill are the drill head and the feeding system. The drill head is a rotary unit that provides the required torque and rotation speed for rotary drilling and for making or breaking the threads of the drill string. The feeding system consists on the mast along which the drill head mounted on a guide carriage moves up and down. Cores are taken from the sea floor by simple pushing a push core barrel (push coring suitable for soft sediments) or by rotating and pushing a rock barrel (rotary drilling for hard rocks). A water pump provides sea water for flushing the drill string for cooling of the drill bit and for removing the drill cuttings.
The core length for each push and rock barrel is 3 m. When the barrel has finished sampling it is recovered out of the drilled hole and stored by the loading arm in a magazine. The next barrel is lowered into the drill hole, a 3 m rod is added and the next 3 m can be sampled. 17 barrels and 16 rods are required to sample the sea floor down to 50 m. The drilled hole can be stabilised by another set of 15 casing tubes.
Since 2008 the MeBo is capable of drilling with wire-line coring technique. After drilling a 2.35 m section the core is recovered using a wire that is latched to the inner core barrel with an overshot. The outer drill string stays in the drilled hole during the entire drilling process. Therefore no casing is required and drill string handling time decreases drastically. Using wire line coring-technique the MeBo can sample the sea floor down to 70 m.