| Abstract |
The deep-sea drilling vessel (D/V) Chikyu is a riser-equipped, dynamically positioned scientific drill ship owned and operated by the Japan Agency for Marine-Earth Science and Technology (JAMSTEC), and built for the purpose of scientific research and exploratory expeditions. The vessel is designed to access scientific targets deeper than previously attempted, to depths of 7000 m below the seafloor, in order to recover core samples in the deep oceanic crust. A wireline retrievable coring system has been adopted for more efficient operations, i.e., the inner core barrel including the core sample is retrieved through the drill pipe by a wireline. The core samples are then investigated for scientific analysis to elucidate the factors affecting global environmental change, earthquakes, biospheric conditions below the seafloor, and the mechanisms involved in volcanic eruptions. The D/V Chikyu is, thus, employed in exploratory expeditions which aim to drill to depths never before possible while also constantly optimizing operations, upgrading equipment and developing advanced technologies in deep sea drilling in order to attain the breakthrough goal of eventually reaching the earth’s mantle. Innovations and improvements of the drilling systems will be vital in order to withstand such extreme environments as temperatures of over 250 deg C and pressures greater than 1000 atm. Efforts are also focused on the development of new types of core barrels including a turbo corer, motor-driven core barrel (MDCB) and core bits as part of research into key technologies of national strategic importance. Constant calibration and improvement of equipment such as the core barrel parts will be carried out for efficient operations. This study introduces the present status in development as well as new conceptual designs and technological work being carried out for coring systems that can achieve high performance and efficiency even under extreme drilling environments. |