View
238
Download
7
Category
Preview:
Citation preview
Borehole SeismicIntroduction
Introduction
Seismic Signals in the
borehole
Borehole Environment
Borehole survey types
Borehole seismic deployment
Overview
A VSP or Vertical Seismic Profile is the process of recording seismic data in a wellbore environment. The geophones are vertical in the earth versus horizontal along it as in surface seismic.
What is a VSP?
Checkshot
Vertical Incidence Walkaway 3D-VSP
DBSeis
Offset VSP
Salt Proximity
Zero Offset
LWD Tool
SeismicMWD
Integrated Seismic Surveys
Pressure &Temperature
Flow &Phase
4CSensors
Borehole Seismic Surveys
Introduction
Seismic Signals in the
borehole
Borehole Environment
Borehole survey types
Borehole seismic deployment
Depth
Time
• Downgoing direct arrival
• Downgoing multiple
• Reflected upgoing primary
• Reflected upgoing multiple
Seismic Signal in the Borehole
Depth
Time
• Time-Depth• Seismic Reflections
Vertical Seismic Profile
Depth
TimeSurface Seismic VSP
Transit
Time (TT)
TT
Reflection
Time (OWT)OWT
TT
TWT = OWT + TT
Reflection
TWT
TWT
One-Way Time vs. Two Way Time
Borehole Multiples
Upgoing Multiples
Borehole Multiples
Downgoing Multiple
Borehole Multiples
All Multiples
Tube waves are generated when surface waves from the source
come in contact with the borehole fluid and become a guided wave
traveling up and down the borehole.
As the tube wave travels vertically in the borehole it pushes the wall
horizontally.
When the geophones are properly clamped to the borehole wall most
of the tube wave energy will be seen in the horizontal geophones.
At changes in the borehole dimensions some of the tube wave energy will be reflected back to the surface. This will also occur when the energy reaches the bottom of the hole.
Tube Wave Energy
Source
Tube Waves
Raw DataOne-Way Time
Dep
thH
ori
zon
tal
Ch
an
nel
Vert
ical
Ch
an
nel
Tube wave
Tube wave
Y
X
HODOGM
Y
X
HODOGM
Surface Seismic Comparison
DepthOffset
Tw
o-W
ay T
ime
One-W
ay
Tim
e
VSP DataSurface Seismic
Introduction
Seismic Signals in the
borehole
Borehole Environment
Borehole survey types
Borehole seismic deployment
Resonance types & effects
Resonance generates signal distortion
Coupling resonance
effect
Modal resonance
effect
Resonance AttenuationReduce tool dimension & mass Increase tool application forceOptimize contact geometry
Combined tools
Shaker
Coupling contacts
Geophones
Isolatingsprings
Versatile Seismic Imager - VSI
Isolated geophone package: 3.5 lbs
Positive mechanical anchoring
Combinable Seismic Imager - CSI
Isolated geophone package: 20 lbs
Positive mechanical anchoring
Array Seismic Imager - ASI
Isolated geophone package: 9 lbs
Magnetic clamping
Shaker Response
Introduction
Seismic Signals in the
borehole
Borehole Environment
Borehole survey types
Borehole seismic deployment
Borehole Seismic HistoryCheckshot Single Trace 2-D Lateral Coverage
Checkshot Surveys
Formation TravelTimes
Formation TravelTimes
FormationVelocities
FormationVelocities
Depth-Velocity Model Inputs
Depth-Velocity Model InputsSurface Seismic Correlation
Surface Seismic Correlation
Wavelet Processing
Wavelet Processing
Acoustic Impedance
Synthetic Seismogram
Surface Seismic
Dep
th (
m)
Time (s)
Source
Geop
hon
es
Depth Model
CHECKSHOT
Zero Offset VSP
Surface SeismicCorrelation
Surface SeismicCorrelationOver-pressure Zone Prediction
Over-pressure Zone PredictionMultiple PatternIdentification
Multiple PatternIdentificationWaveletProcessing
WaveletProcessing
FormationVelocities
FormationVelocities
Corridor Stack
Surface Seismic
Dep
th (
m)
Time (s)
SourceG
eop
hon
es
Depth Model
ZERO OFFSET
VSPImage
Surface Seismic
Dep
th (
m)
Time (s)
Depth Model
SourcesG
eop
hon
es
Vertical Incident VSP
Surface SeismicCorrelation
Surface SeismicCorrelationLateral Coverage Beneath Well
Lateral Coverage Beneath Well
Multiple PatternIdentification
Multiple PatternIdentificationFault and DipIdentification
Fault and DipIdentification
FormationVelocities
FormationVelocities
WALKABOVE
Offset VSP
Surface SeismicCorrelation
Surface SeismicCorrelationFault and DipIdentification
Fault and DipIdentification
Salt ProximityIdentification
Salt ProximityIdentification
Shear WaveAnalysis
Shear WaveAnalysis
Surface SeismicSurvey Design
Surface SeismicSurvey Design
VSP Image
Surface Seismic
Dep
th (
m)
Time (s)
Source
Geop
hon
es
Depth ModelOFFSET
Imaging Walkaway
Surface SeismicCorrelation
Surface SeismicCorrelationFault and DipIdentification
Fault and DipIdentification
Shear WaveAnalysis
Shear WaveAnalysis
Surface SeismicSurvey Design
Surface SeismicSurvey Design
Dep
th (
m)
Source
Geophones
Depth Model
VSP Image
Surface Seismic
WALKAWAY
AVO Walkaway
True Seismic Amplitude
With Changing
Offset
True Seismic Amplitude
With Changing
Offset
P-P and P-SV Analysis
P-P and P-SV Analysis
Reflector
Source Positions P-Wave S-Wave
AVO WALKAWAY
Anisotropy velocity model
Anisotropy velocity model
Q factor analysis
Q factor analysis
Salt Proximity Survey
Provides Accurate Salt Face Image
2D, 2.5D and 3D Imaging Solutions
3D VSPVery High Sub-Surface Imaging Resolution
Exploration and Development Applications
Detailed Preplanning and 3D Modeling Required
3-D VSP
Well 1
Well 2
Well 1
Well 2
3D-VSP Depth Migration
Surface seismic
3D PSDM
3D VSP
Introduction
Seismic Signals in the
borehole
Borehole Environment
Borehole survey types
Borehole seismic deployment
Borehole seismic on Wireline
Applications All seismic applications
Operations - Max deviation
dependant of well liquid type & well geometry (example: so far, ASI ran in 77 deg deviation, in Brine)
DownholeGeophones
Source
ReferenceSensors
RecordingUnit
Downgoing Wavefront
Pit
Pipe Conveyed Acquisition
Applications All seismic applications
Operations Max deviation: no limit (113o exp) Ex : 3 * CSI / MDT / Pex / DSI Extendable CSI sub isolates geophones from tool body & pipes
Wet connect
CSI CSI CSI Pressure sampling
Sonic
Neutron
Gamma density
Tension sub Resistivit
y
Gamma spectrosco
py
Compression sub
Through Drill Seismic TDS
Applications All seismic applications, & particularly...… Position of the drill bit:
on the surface seismic from the target
... Imaging beside the well
... Prediction ahead of the bit
Operations Data acquisition
... Tool Pumped down… Reciprocate between levels… No circulation… Acquisition 10 min max
Min deviation so far = 7 deg Max deviation so far = 90 deg Saving rig time Taking effective and fast decisions
Conventional VSP source
GAC sensor
Drill
bit
TDS Thru-Drill Seis
Logging While Drilling
ApplicationsReal Time checkshots...… Position of the drill bit:
on the surface seismic from the target
… Along with ISONIC: Calibration of ISONIC data & RT Synthetic seismogram
Operations Saving rig time Taking effective and fast decisions
seismic reflector
LWD Tool
sea floorMW
D t
ele
metr
y
SeismicMWD
seismic reflector
Drill Bit
Sensors
Weights
Sensor
sea floor
Source
Drill Bit Seismics
Surface System
Through Tubing Seismic
Applications All seismic applications, & particularly...... Imaging beside the well (coil tubing drilling, well redevelopment, etc)
Operations Data acquisition - Stop production
VSP source
Geophones (GAC)
Simultaneous Acquisition
Applications All seismic applications, & particularly... … Acquiring borehole seismic data before surface processing starts: Velocity anisotropy, Q attenuation, AVO, VSP-guided processing, shear model
Operation Tool stays stationary in the well Platform Joint acquisitions with GP
Recommended