New Application of Sonic Scanner*
in Gas Reservoir Evaluation
Ronarong ParamatikulPetrophysics Domain EngineerData & Consulting Services
Schlumberger
Challenges in Gas Evaluation
Idea of using Sonic Scanner for Gas Evaluation
Processing & Interpretation Workflow
Agenda
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Processing & Interpretation Workflow
Application & Benefit of the New Technique
Conclusion
GR Resistivity Neutron-Density
Gas Field
Oil Field
Challenges in gas evaluation
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Gas Sand
Gas show
during drilling
Source: World Energy Atlas 2002
Sonic Scanner
Combination of monopole and dipole transmitters
13 arrays of receivers
Sonic measurement is a good gas indicator
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Good quality of waveforms for future applications
MU ML MFXD YD
13 x Receivers
Sonic measurement is mainly used for Geophysics & Geomechanics, but not Petrophysics
Sonic measurement is very good gas indicator
Transform compressional & shear slowness into modulus
How to use sonic for gas evaluation?
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Transform compressional & shear slowness into modulus
Use modulus as saturation input to compute gas saturation
Qualitative Quantitative
Gas sand? How much gas?
Gas detection from Sonic
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Gas effect on sonic data
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Sonic Scanner into ELAN Workflow
Data QC
Environmental Correction
Resistivity ELAN
Sonic Scanner
Processing
Data QC
Environmental Correction
Resistivity ELAN
Sonic Scanner
Processing
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Bulk & Shear
Modulus Calculation
Sonic Endpoints
Calibration
Sonic ELAN
Result Review
Bulk & Shear
Modulus Calculation
Sonic Endpoints
Calibration
Sonic ELAN
Result Review
QC & Env Correct Resistivity ELAN Sonic Scanner Modulus Endpoints Sonic ELAN Result Review
Data QC & Environmental Correction
Logging Parameters & Field CalibrationEnvironmental Correction Logging parameters
Field calibrations
Environmental correction
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Good Quality Log For Interpretation
Resistivity ELAN Sonic Scanner Modulus Endpoints Sonic ELAN Result ReviewQC & Env Correct
Resistivity ELAN Interpretation
ELAN is Petrophysical
Interpretation module
Cross plot analysis to determine
endpoints
Equations
Volume
Result
GR ResistivityNeutron
Density Resistivity ELAN
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Use resistivity as equation for
water saturation
Shale endpointD
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Neutron porosity
QC & Env Correct Sonic Scanner Modulus Endpoints Sonic ELAN Result ReviewResistivity ELAN
Use for Sonic Calibration
Sonic Scanner Processing
Sonic waveform preprocessing
Compressional & Shear
Slowness by BestDT module
Compressional Shear
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Unpack & QC Sonic Scanner waveforms
QC & Env Correct Resistivity ELAN Modulus Endpoints Sonic ELAN Result ReviewSonic Scanner
Input for the next step
Bulk Modulus & Shear Modulus Calculation
Modulus from Sonic wave
Slowness to Modulus conversion
Effect of Bulk modulus to gas
Gas effect on bulk modulus
11QC & Env Correct Resistivity ELAN Sonic Scanner Endpoints Sonic ELAN Result ReviewModulus
M = Vp2 x
Bulk Modulus = K = M (4 G /3)
M = Compressional Modulus
G = Shear Modulus
G = Vs2 x
G =(13474.45 x b) / (tsh)2
M =(13474.45 x b ) / (tco)2
K = M (4G / 3)
Conversion to Slowness
Gas effect on bulk modulus
It can be use for Saturation input
New input curves computed
Sonic Endpoints Calibration
12QC & Env Correct Resistivity ELAN Sonic Scanner Modulus Sonic ELAN Result ReviewEndpoints
Volume from Resistivity ELAN Calibration Calibrated data
Sonic ELAN Interpretation
Sonic ELAN Model
Use sonic modulus to be
saturation input
GR ModulusNeutron
Density Sonic ELAN
QC & Env Correct Resistivity ELAN Sonic Scanner Modulus Endpoints Result ReviewSonic ELAN
Results and Finding
GR ResistivityNeutron
Density ModulusResistivity
ELAN
Sonic
ELAN Over calibrated interval
Sonic Resistivity very similar result
Outside calibrated interval
Sonic Resistivity very similar result
What is the different?
Sonic see something where resistivity
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Sonic see something where resistivity
cannot see
Sonic detects gas in the formation
where Resistivity does not
QC & Env Correct Resistivity ELAN Sonic Scanner Modulus Endpoints Sonic ELAN Result Review
Sg > 15%Sg < 3%More gas identified
Applications
1. Sonic interpretation is independent of formation water salinity
2. Sonic sees gas where Resistivity could not e.g. thinly laminated sands
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3. Cased hole gas saturation evaluation
4. Offset wells where no Resistivity data recorded
Example: Well-A to Well-B
All parameters from Well-A
to Well-B
Gas observed in shaly zone
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Resistivity ELAN Sonic ELAN
Example: Thin beds sand with gas
17T-combo with RT Scanner Resistivity ELAN Sonic ELAN OBMI Image
Example: Thin beds sand with gas
Gas seen from
Sonic
18T-combo with RT Scanner Resistivity ELAN Sonic ELAN OBMI Image
Example: Thin beds sand with gas
Gas seen from
Sonic
19T-combo with RT Scanner Resistivity ELAN Sonic ELAN OBMI Image
Example: Thin beds sand with gas
Gas seen from
Sonic
20T-combo with RT Scanner Resistivity ELAN Sonic ELAN OBMI Image
Benefit of using the technique
1. Reduce uncertainty in formation evaluation
2. Gas evaluation in low resistivity pay (e.g. Laminated sand)
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3. New option for gas analysis behind casing
Formation Evaluation
Resistivity RST C/ONMR diffusion
editing
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Dielectric Downhole
Fluid
Analyzer
Neutron
Time lapseGas detection
from SonicGas Saturation
from Sonic
New option for Gas evaluation
THANK YOUTHANK YOU
Q & A
Backup Slides
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LWD Sonic vs WL Sonic in Fast Formation
Good comparable
Compressional Shear
slowness between
SonicVISION vs DSI
SonicVISION compared to DSI
Dipole Transmitters
DSI Sonic Scanner