SEMI-SUBMERSIBLE DRILLING VESSEL WITH A MUD TREATMENT AND CIRCULATION SYSTEM

摘要

A semi-submersible drilling vessel has a deckbox structure and a shaker room. A downward sloping mud return line is provided that passes mud from the diverter to the shaker room. In the shaker room there are one or more shale shaker devices, one or more upstream mud tanks arranged to receive gas cut mud from the one or more shale shaker devices, and a vacuum degasser having an inlet pipe extending into an upstream mud tank, a vacuum tank, a vacuum pump, and an outlet, and a degassed mud tank receiving degassed mud from the outlet of the vacuum degasser. The degassed mud tank has an effective height between the bottom thereof to the operational mud level in said degassed mud tank that is greater than the corresponding effective height of said one or more upstream mud tanks. The degassed mud tank is mounted so that—in operation—the operational mud level in said degassed mud tank is at least 1.5 meter, preferably at least 2 meters, higher than in said one or more upstream tanks with the vacuum degassers self-suction effect causing the mud to be pumped from the upstream tank, via the vacuum degasser, into the degassed mud tank.