Back To Field Services
Jumbo Piston Coring
TDI-BI vessels are equipped with 12m 3-inch diameter piston
cores and 30m 4" Jumbo Piston cores (JPC) that can be
collected at depths in excess of 4,000m. The 3" piston
corer is operated from the midships A-frame. The JPC utilizes
a cantilevered deployment platform over the stern of the vessel
with a rail and capture bucket assembly placed on the deck
of the vessel directly beneath the stern A-frame. The JPC
consists of a 4,000-lb weight stand, a 4" core barrel,
a mechanical trigger, standard schedule 40 PVC liner, a cutting
shoe, and a foil core catcher.
Piston Coring Rig Layout and Operation
Subbottom Chirp profiles are first run to provide near surface
structural information and precise water depth. The vessel
maintains position at the location so the sampler impacts
the prescribed position within the accepted radius of error
(usually 60 ft).
Geotechnical ASTM standardized testing may be performed at
one meter intervals and include Torvane and miniature vane
tests. In addition, UU triaxial compression tests may be performed
on sections with shear strengths greater than 15 kPa using
a 3-in.-diameter plugged sample. Moisture contents are measured
for all UU triaxial and miniature vane test specimens in addition
to Unit weight determination.
A shipboard geotechnical log is prepared for each core that
includes: Core identification number, Coordinates, Water depth,
Core recovery, Digital color photographs, Detailed Lithology,
and Geotechnical testing results.