A challenge to Nankai Trough seismogenic zone - Report of IODP Expedition 358

Abstract

Japan Agency for Marine-Earth Science and Technology（JAMSTEC）owns drilling vessel "Chikyu" and conducted the drilling operation at Nankai Trough Area as one of scientific drilling projects. We have drilled total over 70 holes（Riser/Riserless holes and monitoring wells）at this area until 2019. Riser hole at C0002 site was the one of the main well for the earthquake research field and drilled step by step in 2010, 2012 and 2013. To reach the plate boundary fault, the drilling program of deepening C0002 riser hole during International Ocean Discovery Program（IODP） Expedition 358 in 2018 was planned. For succeeding the drilling operation at C0002 riser hole, geomechanics, expandable casing, continuous circulation system and mud rheology including sealant were discussed and prepared.

This paper introduces the operation results and preparations of IODP Expedition 358.