Site C0010 riserless observatory

C0010 SmartPlug recovery/GENIUSPlug deployment

Site C0010, completed during Expedition 319, is located 3.5 km along strike of previously drilled and cored Site C0004 (Fig. F4). Hole C0010A penetrated a major splay fault (megasplay) at ~410 mbsf. During Expedition 319, Site C0010 was drilled with MWD and a basic suite of LWD tools (geoVISION resistivity tool and gamma ray) to penetrate the megasplay fault at ~410 meters below seafloor (mbsf) and into the footwall to a TD of 560 mbsf. Observatory operations included installing a temporary monitoring package to monitor pore pressure and temperature within the fault zone accessed through a screened casing.

Scientific objectives

The scientific objectives at Site C0010 during Expedition 332 are to retrieve the SmartPlug sensor and packer assembly (see Davis et al., 2009, for details) and to install another temporary monitoring system (Table T2). The retrieval of the SmartPlug will allow the collection of the first observatory data (pressure and temperature) from the shallow section of the megasplay fault as well as allow evaluation of observatory installation procedures in the rough Kuroshio Current. These data will be invaluable in planning for the permanent observatory, due for installation before 2013. After the recovery of the SmartPlug (Fig. F8A), its upgraded version containing an OsmoSampler (Jannasch et al., 2003) as well as a FLOCS microbiology unit (Orcutt et al., 2010), a GENIUSPlug (Fig. F8B), will be installed for continued observations until the deployment of the permanent observatory in the shallow updip end of the megasplay fault.

Operational plan

The SmartPlug was installed during Expedition 319 and will be recovered during this expedition (Saffer et al., 2009) (Fig. F5B). An improved running tool will be used to recover the SmartPlug and for the running in and deployment of the GENIUSPlug.

Contingency plan

The go/no-go decision for installation of the permanent observatory (CORK) will occur on the turning point of 5 December 2010. If the casing is completed by that date but installation of the permanent CORK has not significantly progressed, we will then ask for an additional 12 days to safely complete installation. If, however, casing installation is still ongoing on 5 December, we will ask for 5 additional days to complete casing operations and SmartPlug installation. The worst-case situation will leave Site C0002 cased, cemented, and capped but with no observatory installation at all.