Description
Applications Schematic representation of the RAB Coring Tool (RAB-C).
Specifications
ODP Logging Services, Lamont-Doherty Earth Observatory, Rt. 9W, Palisades, NY 10964
Logging-While-Coring Resistivity-at-Bit System
♦ Core-log data integration capability♦ Assessment of borehole breakouts for local and
regional stress analyses♦ Detection of formation heterogeneity using
azimuthal resistivity images♦ Lithological characterization
The Logging-While-Coring (LWC) system, developed jointly by the Borehole Research Group, Schlumberger Drilling and Measurements, and Texas A&M University, takes advantage of existing logging, drilling and coring technologies and synthesizes them into a powerful new exploration system. Recent improvements in battery technology have enabled the reformatting of the electronics in an 8-inch Schlumberger Resistivity-at-Bit (RAB) tool. By placing smaller batteries in the drill collar wall and fabricating a new resistivity button sleeve, an existing ODP core barrel can pass through the RAB to carry out coring operations while making azimuthal geophysical measurements. The coring tool technology consists of the Motor Driven Core Barrel (MDCB) system developed by Texas A&M, which needed only minor modifications and the fabrication of crossovers and drilling subs. The assembled system was successfully tested at the Genesis test facility in Sugarland, Texas, then successfully deployed at sea to acquire resistivity images and ocean bottom sediment cores at Hole 1249B on Leg 204.
Assembly of the RAB Coring Tool aboard the JOIDES Resolution.
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Retrievable Motor DrivenCore Barrel (MDCB) InnerCore Tube [O.D. 2 7/8"]
RAB [I.D. 3.45"]
Battery
Azimuthal resistivity electrodes [O.D. 9 5/8"]
Azimuthal gamma ray
Field replaceable stabilizer
Bit resistivity electrode
12/2003
Ass
embl
y of
the
RA
B C
orin
g To
ol d
urin
g an
ear
ly te
st in
Tex
as.
RA
B-C
Imag
e S
tatic
nor
mal
izat
ion
NE
SW
RA
B-C
R
esis
tivity
Orie
ntat
ion
020
4060
0 10 20
30 40 50
60 70
00
.51
1.5
1030
50
0 10
20 30 40
50
60 70
BS
AV
(oh
m-m
)D
ensi
ty (
g/cm
3 )
RA
B-C
Cor
e D
ata
Mag
netic
Sus
cept
ibili
ty
(rel
ativ
e un
its)
Depth (mbsf)
Res
isti
vity
imag
e an
d av
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e re
sist
ivit
y da
ta fr
om th
e R
AB
co
ring
too
l pl
otte
d w
ith
phys
ical
pro
pert
ies
data
fro
m
core
s co
llect
ed w
ith
the
resi
stiv
ity-
whi
le-c
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g sy
stem
.