Downhole Measurements

Drill String Tools

Long Term Observatories (CORK)

The CORK (Circulation Obviation Retrofit Kit) allows researchers to isolate boreholes from the ocean water above the seabed and monitor conditions in the hole for long periods of time. The CORK's data logger can records temeperature and pressure data for five years and store it in memory for an additional five years until it can be retrieved by a manned submersible or a ROV. The data is obtained by a string of sensors that hangs from the CORK to the bottom of the borehole. It also has fittings for recovering samples from inside the hole and allows fluid to be injected into the hole for certain kinds of tests. The cork extends above a docking platform for the submersible.

The CORK's purpose is to provide a long term, seafloor observatory intended to allow a monitored and accessible borehole to return to it's pre-drilling state. A printed manuscript appeared in the Leg 139 Initial Reports volume (Davis, Mottl, Fischer, et al., 1992) and describes CORK developement, deployment, and interpretation of preliminary data in some detail. A more complex treatment of CORK post-emplacement operations and data interpretation appears in the Leg 139 Scientific Results volume. Additional CORK operations conducted on Leg 146 are described in Technical Note 10. For tool specifications and schematics see Technical Note 31.