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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

14

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