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  • 1

    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

  • 2

    Agenda

    • Quadrupole measurement overview

    • Quality Control of Quadrupole Shear

    • Successful examples in 12 1/4”, 17 1/2” and 9 7/8” boreholes

  • 3

    +

    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)

    D ep

    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

  • 4

    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

  • 5

    Flexural and Quadrupole Dispersive Waves

    Dipole

    flexural Quadrupole

    Dipole flexural Quadrupole

    Dispersive Modes

  • 6

    Wireline tool Drill Collar

    Frequency

    Wireline

    tool flexural

    Borehole flexural

    Formation shear

    Weak interference

    Wireline dipole

    S lo

    w n

    es s

    Collar

    flexural

    Strong

    interference

    LWD dipole

    S lo

    w n

    es s

    Frequency

    Fast collar

    flexural mode

    Borehole

    flexural mode

    Why LWD Quadrupole and not Dipole like WL? LWD requires a rigid collar compromising dipole shear

  • 7

     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

  • 8

    Predictable Acoustics

    Modeling

    Real data

    Quadrupole mode (Mode search/Modeling)

    Dispersion curve

    without tool

    Acoustic Test Pits Modeling of the Quadrupole

  • 9

    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

    L a

    m . S

    /S

    S h

    a le

    S

    a n

    d /S

    h a

    le

    Quadrupole Shear Quality Control Display

    9

    0 kHz 20

    0 kHz 8

    0 kHz 8

  • 10

    Examples

  • 11

    Example #1: Quadrupole in 9 7/8” pilot hole

    Raw 1-3 kHz BP filter

    6 00

    m

  • 12

    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

    1 20

    m

  • 13

    Example #2: Quadrupole in 12 1/4” hole

    Raw

    1-3.5 kHz

    BP filter

    4 00

    m

  • 14

    4 00

    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

  • 15

    • 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

  • 16

    • 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

    70 0

    m

  • 17

    Monopole Compressional LWD vs WL

    LWD Quadrupole vs WL Dipole

    Example #3: Quadrupole in 17 1/2” hole 1

    70 0

    m

  • 18

    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

  • 19

    Acknowledgements

    Schlumberger – Nicholas Robinson, Field test coordinator, SKK

    – Hiroaki Yamamoto, Fuchinobe, SKK

    – David Scheibner, Houston HFE

    – Co-author: Hathairat Watcharophat, Aberdeen, UK

  • 20

    Thanks