borehole seismic introduction. seismic signals in the borehole borehole environment borehole survey...

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


borehole




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


borehole




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


borehole




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 SeismicCorrelationLateral Coverage Beneath Well

Lateral Coverage Beneath Well

Multiple PatternIdentification

Multiple PatternIdentificationFault and DipIdentification

Fault and DipIdentification

FormationVelocities

FormationVelocities

WALKABOVE

Offset VSP


Surface SeismicCorrelationFault and DipIdentification


Salt ProximityIdentification

Salt ProximityIdentification

Shear WaveAnalysis

Shear WaveAnalysis

Surface SeismicSurvey Design


VSP Image

Surface Seismic

Dep

th (

m)

Time (s)

Source

Geop

hon

es

Depth ModelOFFSET

Imaging Walkaway


Surface SeismicCorrelationFault and DipIdentification


Shear WaveAnalysis

Shear WaveAnalysis



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


borehole




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

borehole seismic introduction. seismic signals in the borehole borehole environment borehole survey...

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