Abstract
Pressure Temperature Core Sampler (PTCS) was designed and developed as a special coring tool in the methane hydrate (MH) R & D project in Japan. In order to recover in-situ methane hydrate bearing sediments without major dissociation while retrieving to the surface, inner barrel of PTCS retains downhole pressure by closing a ball valve and retains downhole temperature by an insulated chamber. A 2-5/8"(66.7 mm) OD × 3 m core sample is cut by 10-5/8"(269.9 mm) OD core bit and the inner barrel containing the core sample is wireline retrievable through special 6-5/8"(168.3 mm) drillpipe. The 1st PTCS was used on the occasion of the drilling campaign named MITI “Nankai Trough” in 1999-2000. After several elements had been improved, the 2nd PTCS was used on the drilling campaign named METI exploratory test wells “Tokai-oki to Kumano-nada” in 2004. In this campaign, the 2nd PTCS retrieved 161.3 m of high quality MH core samples at approximately 80% recovery.
