Development of the Waste Mud Treatment System for Drilling Vessel 'CHIKYU'

摘要

The deep sea drilling vessel "CHIKYU" was completed in July 2005. The mission, which will be carried out with "CHIKYU ", is to gather geologic core samples under the seabed at the sea of deep water depth. The core samples and the drilled holes from which the core samples will be gathered will be used for the scientific studies to make clear the global environmental change, earthquake outbreak mechanism and biosphere under the sea-bed. The studies for these areas have been carried out under a scientific plan of Integrated Ocean Drilling Program (IODP). It is necessary to gather core samples from a deeper formation so that we can make these studies succeed. Riser system and mud circulation system have been adopted to "CHIKYU" in order to gather core samples from a deep formation under the seabed. This is one of the drilling drilling vessel and drilled hole. Risers are used As A retulrn line of keeoping thhe pressure balance between in and out of a hole, and so on. This means that mud circulation is be able to stabilize a well and as a result enables great depth drilling. On the other hand, mud circulation generates drilling waste such as waste mud and cuttings on board. In the oil industry, the drilling waste is usually abandoned into the sea. However, in late years the interest for an environmental problem has risen, and a standard of underwater abandonment of a drilling waste tends to become severe.