Sevan Ultra Deep Water Drilling Rig (’UDW’)
Sevan Drilling’s UDWs are based on Sevan Marine’s unique, proven and patented cylindrical hull design. Sevan Drilling has a non-exclusive perpetual right to use the Sevan design for drilling applications. The design provides for the following advantages compared to traditional drilling units:
Independence of environmental directionality
The cylindrical hull shape makes the vessels responses independent of wind, waves and current headings and optimum heading can be selected freely based on on-going operations. Conditions with wind driven waves and swell from different directions will not affect the operation due to the very low pitch and roll motions of the vessel. There is no need for compromising between motions and power consumption in case of bi-directional waves and current and minimum power consumption will be obtained regardless of environmental conditions.
High variable deck load capacity
With the large displacement and stability reserves of the cylindrical hull, the variable deck load capacity is above 15 000 tons. Paired with generous tank capacities this significantly reduces the need for resupply and thus also the logistic cost.
Simplified construction
The cylindrical hull may be built using traditional section building method based on prefabrication of large, pie-slice shaped modules. The lower hull may be assemlied on a slip way, in a dry dock or on a floating barge and with final completion quaside.
Lower hull used for storage
The lower hull of the vessel is utilized for storage of consumable fluids as fuel oil, drilling fluids, dry bulk materials, ballast water and utility systems. Storage of produced oil from extended well tests / early production may optionally be arranged .
Upper level
The upper section of the hull carries the main power generation plants, mud handling systems, derrick with drilling equipment and storage for risers, drill-string, casings, well testing equipment and similar.
Protected moon pool
The drilling operation is executed through the centre moon pool which provides for a protected environment for launch and recovery of the BOP and riser. The completely enclosed moon pool also protects the riser and allows the vessel to safely operate even in ice-infested areas.
Station keeping
The Sevan UDWs are equipped with a dynamic positioning system in accordance with class 3 requirements keeping position by controlling azimuth thrusters. For operation in shallow waters or in areas with ice, a conventional mooring system may be installed in combination with the DP system.
Independence of environmental directionality
The cylindrical hull shape makes the vessels responses independent of wind, waves and current headings and optimum heading can be selected freely based on on-going operations. Conditions with wind driven waves and swell from different directions will not affect the operation due to the very low pitch and roll motions of the vessel. There is no need for compromising between motions and power consumption in case of bi-directional waves and current and minimum power consumption will be obtained regardless of environmental conditions.
High variable deck load capacity
With the large displacement and stability reserves of the cylindrical hull, the variable deck load capacity is above 15 000 tons. Paired with generous tank capacities this significantly reduces the need for resupply and thus also the logistic cost.
Simplified construction
The cylindrical hull may be built using traditional section building method based on prefabrication of large, pie-slice shaped modules. The lower hull may be assemlied on a slip way, in a dry dock or on a floating barge and with final completion quaside.
Lower hull used for storage
The lower hull of the vessel is utilized for storage of consumable fluids as fuel oil, drilling fluids, dry bulk materials, ballast water and utility systems. Storage of produced oil from extended well tests / early production may optionally be arranged .
Upper level
The upper section of the hull carries the main power generation plants, mud handling systems, derrick with drilling equipment and storage for risers, drill-string, casings, well testing equipment and similar.
Protected moon pool
The drilling operation is executed through the centre moon pool which provides for a protected environment for launch and recovery of the BOP and riser. The completely enclosed moon pool also protects the riser and allows the vessel to safely operate even in ice-infested areas.
Station keeping
The Sevan UDWs are equipped with a dynamic positioning system in accordance with class 3 requirements keeping position by controlling azimuth thrusters. For operation in shallow waters or in areas with ice, a conventional mooring system may be installed in combination with the DP system.
For further information on the Sevan Design, reference is made to: www.sevanmarine.com