Logging-While-Drilling Resistivity-at-Bit...
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Description Applications Schematic illustration of the Resistivity-at- Bit tool (LWD-RAB). Specifications ODP Logging Services, Lamont-Doherty Earth Observatory, Rt. 9W, Palisades, NY 10964 Logging-While-Drilling Resistivity-at-Bit Tool ♦ Detection of resistivity heterogeneity via azimuthal resistivity images ♦ Lithology estimation ♦ Instantaneous detection of casing and coring points ♦ Accurate resistivity when mud is salty or formation resistivity is high ♦ Detection of early invasion of borehole fluids into the formation The Schlumberger Resistivity-at-Bit tool (LWD-RAB) makes azimuthal resistivity and gamma ray measurements while drilling. Using an azimuthal positioning system, measurements are acquired around the borehole to create a high resolution, 360-degree resistivity image of the drilled hole. The RAB tool may be connected directly behind the bit or further back in the bottom hole assembly. It may be run with other LWD tools such as the ADN, ISONIC or NMR. Typically, the RAB data are stored in memory within the tool and retrieved at the end of the bit run. As an option, the data may be transmitted to a surface acquisition system if a Measurement-While-Drilling (MWD) power pulse tool is run in conjunction with the RAB. Assembly of the RAB tool aboard the JOIDES Resolution. Optional uphole connector Batteries Upper sensor Middle sensor, containing focused ring electrode Azimuthal gamma ray Field-replaceable stabilizer Lower sensor Float valve bore Rbit electrode : t h g i e w l o o T m b l 0 0 2 1 : h t g n e l l o o T ) m 8 0 . 3 ( t f 1 . 0 1 : e g n a r e r u t a r e p m e T ) C ° 0 5 1 o t ° 5 2 - ( F ° 0 0 3 o t ° 3 1 - : r e t e m a i d e d i s t u o l a n i m o n r a l l o c l l i r D . n i 5 7 . 6 : ) l a h t u m i z a ( r e t e m a i d e d i s t u o . x a m r a l l o c l l i r D . n i 5 2 1 . 8 : r e w o P ) s r h + 0 0 2 ( k c a p y r e t t a b m u i h t i L : e u q r o t m u m i x a m d e d n e m m o c e R f b l - t f 0 0 0 , 6 1 : y c a r u c c a t n e m e r u s a e m y t i v i t s i s e R e g n a R e d o r t c e l e d e s u c o f & t i B l a h t u m i z A 1 - 2 . 0 % 0 2 - / + % 0 2 - / + 0 0 0 1 - 2 % 5 - / + % 5 - / + 0 0 0 2 - 0 0 0 1 % 0 1 - / + % 0 2 - / + 0 0 0 , 0 2 - 0 0 0 2 % 0 2 - / + - - - : s n o i t a c i f i c e p s y a r a m m a G : e g n a R s t i n u I P A 0 5 2 - 0 : y t i l i b a t a e p e r l a c i t s i t a t s a m g i s e n O r h / t f 0 0 1 t a % 3 < ) g n i g a r e v a l e v e l - 3 , n o i t a m r o f I P A - 0 1 ( r h / t f 0 5 t a % 2 < : e t a r w o l f m u m i x a M n i m / l a g 0 0 8 : e r u s s e r p g n i t a r e p o m u m i x a M i s p 0 0 0 , 8 1 : t i b n o t h g i e w m u m i x a M L / 0 0 0 , 0 0 0 , 4 7 = F 2 s i L e r e h w ( f b l ) t e e f n i s r e z i l i b a t s n e e w t e b e c n a t s i d : d a o l g n i r r a j m u m i x a M f b l 0 0 0 , 0 3 3
Transcript of Logging-While-Drilling Resistivity-at-Bit...
Description
Applications
Schematic illustration of the Resistivity-at-Bit tool (LWD-RAB).
Specifications
ODP Logging Services, Lamont-Doherty Earth Observatory, Rt. 9W, Palisades, NY 10964
Logging-While-DrillingResistivity-at-Bit Tool
♦ Detection of resistivity heterogeneity via azimuthal resistivity images
♦ Lithology estimation♦ Instantaneous detection of casing and coring
points♦ Accurate resistivity when mud is salty or
formation resistivity is high♦ Detection of early invasion of borehole fluids
into the formation
The Schlumberger Resistivity-at-Bit tool (LWD-RAB) makes azimuthal resistivity and gamma ray measurements while drilling. Using an azimuthal positioning system, measurements are acquired around the borehole to create a high resolution, 360-degree resistivity image of the drilled hole. The RAB tool may be connected directly behind the bit or further back in the bottom hole assembly. It may be run with other LWD tools such as the ADN, ISONIC or NMR. Typically, the RAB data are stored in memory within the tool and retrieved at the end of the bit run. As an option, the data may be transmitted to a surface acquisition system if a Measurement-While-Drilling (MWD) power pulse tool is run in conjunction with the RAB.
Assembly of the RAB tool aboard the JOIDES Resolution.
Optional uphole connector
Batteries
Upper sensor
Middle sensor, containing focused ring electrode
Azimuthal gamma ray
Field-replaceable stabilizer
Lower sensor
Float valve boreRbit electrode
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A c
ompa
riso
n be
twee
n Lo
ggin
g-W
hile
-Dri
lling
Res
istiv
ity-a
t-B
it (R
AB
) and
wir
elin
e lo
g da
ta. T
he m
easu
rem
ents
pro
vide
ele
ctri
cal
imag
es o
f the
bor
ehol
e w
all (
left
sid
e) a
nd lo
g cu
rves
of e
lect
rica
l res
isti
vity
and
nat
ural
rad
ioac
tivi
ty (r
ight
sid
e). T
he L
WD
dat
a (i
mag
es, d
eep-
, med
ium
-, a
nd sh
allo
w-b
utto
n re
sist
ivit
y cu
rves
, and
gam
ma
ray
profi
le) s
how
frac
ture
pat
tern
s, a
ltera
tion
tren
ds
(den
oted
by
arro
ws)
, and
hig
h ga
mm
a ra
y va
lues
that
may
be
indi
cativ
e of
hyd
roth
erm
al fl
uid
flow
alo
ng fr
actu
res.
(Fig
ure
cour
tesy
of
the
OD
P Le
g 19
3 sh
ipbo
ard
part
y.)
pipe
dep
th w
irelin
e
HN
GS
Pota
ssiu
m (w
t%)
HN
GS
Thor
ium
(ppm
)
02 5
HN
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Ura
nium
(ppm
)
NG
T G
amm
a R
ay (S
GR
)
HN
GS
Gam
ma
Ray
(HSG
R)
030
0(g
API
)
RA
B G
amm
a R
ay (G
R)
Res
istiv
ity D
eep
(ID
PH)
Res
istiv
ity M
ediu
m (I
MPH
)
0.1
100
(Ωm
)
RAB
RBD
RAB
RB
M
RAB
RBS
0 20
40 60 80 10
0
120
140
160
Depth (mbsf)
FMS
Cal
iper
(C1)
FMS
Cal
iper
(C2)
61 6
(inch
es)
FMS
Stat
ic N
orm
aliz
atio
nD
ynam
ic N
orm
aliz
atio
n
RA
BSt
atic
Nor
mal
izat
ion
Dyn
amic
Nor
mal
izat
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