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Quadrupole LWD measurement in large borehole
and slow formation Shear velocity. A successful introduction of the LWD multipole tool
for large borehole size in the North Sea
Marcelo Cecena
LWD Acoustic Domain Champion
Schlumberger, Aberdeen
DEVEX 2014, AECC, Aberdeen
6-7 May 2014
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Agenda
• Quadrupole measurement overview
• Quality Control of Quadrupole Shear
• Successful examples in 12 1/4”, 17 1/2” and 9 7/8” boreholes
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+
Monopole Wave Propagation
Monopole
Shear GR Monopole
Compressional 15 2 5 0
15 4 5 0
15 6 5 0
15 8 5 0
16 0 5 0
16 2 5 0
16 4 5 0
16 6 5 0
16 8 5 0
0 5 0 10 0 15 0
GR (gapi)
Dep
th (
ft)
4 0 6 5 9 0 115 14 0
MH_DTc (us/ft)
14 0 19 0 2 4 0 2 9 0 3 4 0
MH_DTs (us/ft)
1,60
0 ft
Why LWD Multipole Sonic? Monopole Shear cannot provide DT shear in slow formation
Unconsolidated
Consolidated
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Multipole LWD Wideband multipole
transmitters enable
monopole,
quadrupole, and
Stoneley
measurements.
Stoneley
Open permeable
fracture evaluation
for all mud types
Monopole
Real-time P&S
Quadrupole
Shear irrespective
of mud slowness
48 wideband digital
receivers.
4-in inter-receiver spacing
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Flexural and Quadrupole Dispersive Waves
Dipole
flexural Quadrupole
Dipole flexural Quadrupole
Dispersive Modes
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Wireline tool Drill Collar
Frequency
Wireline
tool flexural
Borehole flexural
Formation shear
Weak interference
Wireline dipole
Slo
wn
ess
Collar
flexural
Strong
interference
LWD dipole
Slo
wn
ess
Frequency
Fast collar
flexural mode
Borehole
flexural mode
Why LWD Quadrupole and not Dipole like WL? LWD requires a rigid collar compromising dipole shear
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No flat tail at low frequencies unlike dipole
Dispersion at low frequency limit is small
but not zero
One single shear from quadrupole
Model input
(DTs = 160)
(DTm = 220, BHD = 6.5”)
Borehole quadrupole mode
LWD dipole mode
Shear (DTs)
Collar quadrupole mode
Quadrupole Waveforms (model)
Quadrupole Dispersion
Wireline Borehole dipole mode
Quadrupole Shear A dispersive mode
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Predictable Acoustics
Modeling
Real data
Quadrupole mode (Mode search/Modeling)
Dispersion curve
without tool
Acoustic Test Pits Modeling of the Quadrupole
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X300
X400
X500
X600
X700
X800
X900
Y000
Y100
Y200
Y300
Y400
Y500
Y600
Y700
Y800
Track
1,2 Other Logs
3 Monopole/
Quadrupole Overlay
4 QP
Spect.
5 QP Coh.
Projection
6 QP Disper-sion
Projection
7 QP Disper-sion
Match
8 QP Sembl-
ance Spect.
9 QP Wvfm
VDL
La
m. S
/S
Sh
ale
S
an
d/S
ha
le
Quadrupole Shear Quality Control Display
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0 kHz 20
0 kHz 8
0 kHz 8
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Examples
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Example #1: Quadrupole in 9 7/8” pilot hole
Raw 1-3 kHz BP filter
600
m
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Example #1: Quadrupole in 9 7/8” pilot hole
• Field A, Offshore Norway
• Vertical wellbore, Shallow section
• DTCO: 145 -174 us/ft
• DTSM up to 590 us/ft
120
m
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Example #2: Quadrupole in 12 1/4” hole
Raw
1-3.5 kHz
BP filter
400
m
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400
m
Example #2: Multipole results in 12 1/4” hole
• Field B, offshore Norway
• Maximum borehole deviation 13°
• Water base mud
• DTCO: 100 – 145 us/ft
• DTSM up to 420 us/ft
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• Field C, Offshore Norway
• Vertical wellbore
• Sea water mud
• DTCO : 117 – 195 us/ft
• DTSM : 248 – 980 us/ft
Example #3: Quadrupole results in 9 7/8” pilot hole
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• Field C, Offshore Norway
• Oil Based Mud
• DTCO : 88 - 160 us/ft
• DTSM : 180 - 547 us/ft
Example #3: Quadrupole in 17 1/2” hole 1
700
m
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Monopole Compressional LWD vs WL
LWD Quadrupole vs WL Dipole
Example #3: Quadrupole in 17 1/2” hole 1
700
m
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Quadrupole validation examples from North Sea
• 24 success jobs to date in UK, Norway, Netherlands
Hole Size (in.) No. of jobs Summary
12 1/4 18 Good RT monopole, QP inversion
17 1/2 2 OBM – QP shear up to 661 us/ft
16 1/2 1 DTCO 90-205, DTSM 190 – 270 us/ft
9 7/8 3 Slow QP shear up to 980 us/ft
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Acknowledgements
Schlumberger – Nicholas Robinson, Field test coordinator, SKK
– Hiroaki Yamamoto, Fuchinobe, SKK
– David Scheibner, Houston HFE
– Co-author: Hathairat Watcharophat, Aberdeen, UK
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Thanks
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