HR: 0830h
AN: PP21B-0479
TI: Heave Compensated GLAD800 Coring from the R/V Knorr: a Progress Report
AU: * Nielson, D
EM: dnielson@eng.utah.edu
AF: DOSECC, Inc. and University of Utah, PO Box 58857, Salt Lake City, UT 84158 United States
AU: Mountain, G
EM: mountain@ldeo.columbia.edu
AF: Lamont-Doherty Earth Obs. of Columbia University, RT 9W, Palisades, NY 10964 United States
AU: Pardey, M
EM: mpardey@qdtech.com
AF: QD Tech, Inc., 4558 South Kayland Circle, Salt Lake City, UT 84117 United States
AU: Austin, J
EM: jamie@utig.ig.utexas.edu
AF: University of Texas Institute for Geophysics, 4412 Spicewood Springs Rd., Austin, TX 78759-8500 United States
AU: Alexander, C
EM: clark@skio.peachnet.edu
AF: Skidaway Institute of Oceanography, 10 Ocean Science Circle, Savannah, GA 31411 United States
AB: Despite potential applications to studies of stratal architecture, sea-level history, land-sea interaction, and rapid climate change, scientific drilling with high core recovery in shallow marine settings has been thwarted by several challenges. Among these has been the problem of maintaining hole stability while penetrating unconsolidated lithologies from a floating, open-ocean platform. We report on progress in overcoming this barrier. The GLAD800 coring system, originally developed as a joint venture between the International Scientific Drilling Program and DOSECC to collect long, high-resolution cores in modern lakes, has been adapted for deploying from the R/V Knorr. As in lake-based operations, the drilling system can continuously sample sediments of different composition and stiffness to a total depth of 800m below the rig floor using HWT drill rods and riser pipe. Core is collected in standard ODP-size plastic liners. A modular design provides inexpensive and easily transportable operations. The latest advance is the installation of an active heave compensation (AHC) system that accommodates as much as 8 feet of vertical rig motion. This minimizes excursions in the total weight of the bit at the cutting face, a major concern in achieving the high core recovery needed for scientific purposes. We show results of testing this AHC-equipped GLAD800 rig during a 5-day operation in November. We drilled through the existing 'moon pool' of the R/V Knorr on the outer shelf south of Martha's Vineyard. This technological development and ship time is funded by the Office of Naval Research, and if successful, will be extended to core numerous drill holes 10's to 100's of meters into the New Jersey shelf during 2002.
DE: 3022 Marine sediments--processes and transport
DE: 3094 Instruments and techniques
DE: 4219 Continental shelf processes
DE: 8105 Continental margins and sedimentary basins
SC: PP
MN: 2001 AGU Fall Meeting