Japan Drilling Co., Ltd.

Hiroyasu Ishiguro

Hiromitsu Yamamoto

A dual hoist derrick system for deep sea drilling, capable of elevating a very long and massive heavy object involved in a drilling for deep sea, is provided with a normal drilling hoisting system and a heavy load hoisting system arranged on a single derrick in parallel. The derrick is mounted on a skid movable in a horizontal direction. The skid is provided with a cut broader than a blow-out prevention device, so that the skid may travel to a position of the blow-out prevention device to lift up the blow-out prevention device. The system contributes to speeding up in hoist speed of offshore drilling units for deep sea, reducing working hours and improvement in safety.

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Minato-ku, Japan

Hiroyasu Ishiguro