Overview of Utah Tomography and Modeling/Migration (UTAM) Chaiwoot B., T. Crosby, G. Jiang, R. He, G. Schuster, Chaiwoot B., T. Crosby, G. Jiang, R. He, G. Schuster, J. Sheng, J. Yu, M. Zhou and Xiang Xiao

2004 UTAM Consortium AramcoBP-AmocoBGPGeotomoChevron-TexacoConoco-Phillips IMPINCOSisimageUnocalVeritasWestern-Geco ($24 K/year)

Started 1988 Started sponsors/year10-18 sponsors/year $24,000/year membership$24,000/year membership Benefits : Yearly meeting: Feb. 3-4Benefits : Yearly meeting: Feb. 3-4 Annual+midyr Report Software Goal: Innovative Imaging/Modeling Goal: Innovative Imaging/Modeling UTAM

Jianhua Yu, Min Zhou Gerard T. Schuster University of Utah Interferometric Imaging below Salt And Overburden

Outline Motivation Interferometric Imaging Synthetic Data Conclusions

Outline Motivation Interferometric Imaging Synthetic & Field Data Conclusions

Problems with VSP or CDP Salt Imaging Quality? Salt v(x,y,z) not known Static errors ?

Outline Motivation Interferometric Imaging Synthetic & Field Data Conclusions

Uninteresting Part of Medium How do you remove kinematic effects of propagating through unintersting parts of medium?

Pick Direct Arrival Time T and shift all Traces by T M M {M T M

M {MT Shifting Traces Removes Kinematic Effects Of Propagating through Uninteresting Parts of Medium

M Shifting Traces Removes Kinematic Effects Of Propagating through Uninteresting Parts of Medium

M Shifting Traces Removes Kinematic Effects Of Propagating through Uninteresting Parts of Medium.. M M m(x) = (g, t + t ) gx g MxMxMxMxgx Kirchhoff Migrate psuedo-shot gathers Kirchhoff Migrate psuedo-shot gathers Source Moved to Depth Can replace time-shifted traces by crosscorrelograms

M M M m(x) = (g, t + t ) gx g MxMxMxMxgx Kirchhoff Migrate psuedo-shot gathers Kirchhoff Migrate psuedo-shot gathers Can replace time-shifted traces by crosscorrelograms

M M M m(x) = (g, t + t ) gx g MxMxMxMxgx Kirchhoff Migrate psuedo-shot gathers Kirchhoff Migrate psuedo-shot gathers Can replace time-shifted traces by crosscorrelograms

M M M m(x) = (g, t + t ) gx g MxMxMxMxgx Kirchhoff Migrate psuedo-shot gathers Kirchhoff Migrate psuedo-shot gathers Can replace time-shifted traces by crosscorrelograms

M M M m(x) = (g, t + t ) gx g MxMxMxMxgx Kirchhoff Migrate psuedo-shot gathers Kirchhoff Migrate psuedo-shot gathers Can replace time-shifted traces by crosscorrelograms

M M M m(x) = (g, t + t ) gx g MxMxMxMxgx Kirchhoff Migrate psuedo-shot gathers Kirchhoff Migrate psuedo-shot gathers Can replace time-shifted traces by crosscorrelograms

M M M m(x) = (g, t + t ) gx g MxMxMxMxgx Kirchhoff Migrate psuedo-shot gathers Kirchhoff Migrate psuedo-shot gathers Can replace time-shifted traces by crosscorrelograms

Interferometric Summary Eliminates source statics and uninteresting parts of the medium. Lower source to be near target.

Interferometric Summary Eliminates source+rec statics and uninteresting parts of the medium. Reference layer Lower source+rec. to be near target.

Outline Motivation Interferometric Imaging Synthetic CDP Data & Field Data Conclusions

Shots: 280 Shot interval: 10 m Receivers: 300 Receiver interval: 10 m Temporal interval:1ms X (km) Depth (km) Salt model

X (km) Depth (km) True velocity model

X (km) Time (s) CSG 100 Pick Traveltime Subsalt Reference Reflection

X (km) Depth (km) Kirmig with inaccurate salt dome boundary

X (km) Depth (km) RT migration with inaccurate salt dome boundary

X (km) Depth (km) Standard mig Correct velocity X (km) Standard mig Incorrect velocity RT mig

Outline Motivation Interferometric Imaging Synthetic HSP Data & Field Data Conclusions

0 km 5 km 0 km 5 km Mig. Image+Corr. Vel. 0 km 1.2 s 0 km 1.2 km 0 km 1.2 km 0 km 1.2 km 0 km 1.2 km 0 km 1.2 km HSP Shot Gather Salt Model HSP Interferometric Imaging

0 km 5 km 0 km 5 km Mig. Image+Corr. Vel. HSP Interferometric Imaging 0 km 1.2 s 0 km 1.2 km 0 km 1.2 km 0 km 1.2 km 0 km 1.2 km 0 km 1.2 km HSP Shot Gather Salt Model HSP Interferometric Imaging

0 km 5 km 0 km 5 km Mig. Image+Corr. Vel. 0 km 1.2 s 0 km 1.2 km 0 km 1.2 km 0 km 1.2 km 0 km 1.2 km 0 km 1.2 km Salt Model HSP Shot Gather HSP Image HSP Interferometric Imaging

0 km 5 km 0 km 5 km Mig. Image+Corr. Vel. 0 km 1.2 s 0 km 1.2 km 0 km 1.2 km 0 km 1.2 km 0 km 1.2 km 0 km 1.2 km Salt Model HSP Shot Gather HSP Image SWI-HSP Image Garbage HSP Interferometric Imaging

0 km 5 km 0 km 5 km Mig. Image+Corr. Vel. 0 km 1.2 s 0 km 1.2 km 0 km 1.2 km 0 km 1.2 km 0 km 1.2 km 0 km 1.2 km Salt Model HSP Shot Gather HSP Image SWI-HSP Image Garbage No Need for V HSP Interferometric Imaging

Outline Motivation Interferometric Imaging Synthetic VSP Data & Field Data Conclusions

VSP Data 0 km 2 km 0 km 3 km Image Below Salt Without Knowing Salt Velocity

X (m) Depth (m) Interferometric Image

Well 2 0 Depth (km) 0 3X (km) SEG/EAGE Model 256 Sources V = km/s

Time (s) X (km) X (km) Xcross 60 CRG 60

Depth (km) X (km) Kirchh Mig (45) Xcorr Mig (45) Xcorr. Mig ( 15’)

Outline Motivation Interferometric Imaging Synthetic VSP Data & Field Data Conclusions

Time (s) Depth (ft) Raw Data(CRG15)

Time (s) Depth (ft) Ghosts

Depth (ft) X (ft) 0400 X (ft) Standard migXcorr. mig

SUMMARY Interferometric Imaging: Kinematically equivalent to sources-receivers below datumInterferometric Imaging: Kinematically equivalent to sources-receivers below datum Interferometric TomographyInterferometric Tomography True wave equation statics w/o V(x,y,z)True wave equation statics w/o V(x,y,z) HSP, VSP and CDP dataHSP, VSP and CDP data Salt + Overburden

SUMMARY Interferometric Imaging: Kinematically equivalent to sources-receivers below datumInterferometric Imaging: Kinematically equivalent to sources-receivers below datum Interferometric TomographyInterferometric Tomography True wave equation statics w/o V(x,y,z)True wave equation statics w/o V(x,y,z) HSP, VSP and CDP dataHSP, VSP and CDP data Salt + Overburden

Crosscorrelogram Migration Conclusions Eliminate the static errors in the well No need to know source (RVSP) or receiver location (VSP) Half sensitivity to velocity migration errors than mult. migration by “mirrors”. Increased illumination coverage in the VSP image. VSP ->CDP

Conclusions Loss of some lateral resolution? Be careful about virtual multiple Xcorr Narrow Angle Kirchhoff Wide Angle vs Ghost is weaker than primary Extra summation compared to KM

Outline Motivation Crosscorrelation Migration SEG/EAGE Model 2-D RVSP Field Data Conclusions

Well 2 0 Depth (km) 0 3X (km) SEG/EAGE Model 256 Sources V = km/s

Well 2 0 Depth (km) 03X (km) Receiver interval: 10 m Receiver depth range: km Receiver number: 91 Sample interval: 1 ms Recording length: 3 s Well location: (1.5 km, 0 km) Source interval: 10 m Source number: 256 Acquisition Parameters: 1 km

Time (s) Depth (km) CSG 160

Time (s) Depth (km) Ghosts (CSG 160)

Time (s) X (km) X (km) Xcross 60 CRG 60

Depth (km) X (km) Kirchh Mig (45) Xcorr Mig (45) Xcorr. Mig ( 15’)

Static errors (ms) Well Depth (m) Raw Data Static Errors at Well

Depth (km) 0.5 Kirchhoff Migration Static Error: 0 X (km) Static Error: 25 ms 2.5 Static Error: 50ms

Depth (km) 0.5 Crosscorrelation Migration Static Error: 0 X (km) Static Error: 25ms 2.5 Static Error: 50 ms

Velocity Model Primary vs Multiple Image X (km) Depth (km)

Contents Motivation Crosscorrelation Imaging Condition SEG/EAGE Model 2-D RVSP Field Data Conclusions

Time (s) Depth (ft) Raw Data(CRG15)

Time (s) Depth (ft) Ghosts

524 Trace No. Time (s) xcorr data (muted) Time (s) Trace No. Field Data ( CSG 25 ) Raw data (muted) Master trace

Depth (ft) X (ft) 0400 X (ft) Standard migXcorr. mig

Depth (ft) Standard Well data Xcorr. Exxon Data

Outline Motivation Crosscorrelation Migration SEG/EAGE Model 2-D RVSP Field Data Conclusions

Crosscorrelogram Migration Conclusions Eliminate the static errors in the well No need to know source (RVSP) or receiver location (VSP) Half sensitivity to velocity migration errors than mult. migration by “mirrors”. Increased illumination coverage in the VSP image. VSP ->CDP

Conclusions Loss of some lateral resolution? Be careful about virtual multiple Xcorr Narrow Angle Kirchhoff Wide Angle vs Ghost is weaker than primary Extra summation compared to KM

Acknowledgments UTAM sponsors Exxon for 2-D field data J. Claerbout + J. Rickett II evolved from daylight imaging

Depth (ft) X (ft) 0400 X (ft) Standard migXcorr. mig

Geological Model Depth(km) X(km) (2001)

Migration Result Using Crosscorrelation Imaging Time (s) 2.1 X (km) Too simple? Widen illumination? If there are static errors in well?

Why Use Crosscorrelation Migration? Widen the illumination coverage in the VSP image VSP geometry Equivalent surface geometry Xcorr

Seismic Ghost Reflection Direct Ghost ? Find R(x,z) but not know source location

Direct Ghost 12Directx Directx Master Seismic Ghost Reflection Seismic Interferogram: Correlate Traces t }M m(x) = (g, t + t ) gx g MxMxMxMxgx M Kirchhoff Migrate psuedo-shot gathers Kirchhoff Migrate psuedo-shot gathers Ghost Direct has kinematics of primary reflection x M

Well Source Receiver Primary Direct Wave Ghost RVSP

x g s Ghost Reflection Imaging Condition Ghost Reflection Imaging Condition:

x g s After Crosscorrelation of Two Traces at Locations g & g’

x g s

x g s

Recall Green’s Theorem Every Surface Point = Source Point

Why is there insensitivity to static errors in the well? s g’g x Static errors

Crosscorrelogram Migration Migrated Image Crosscorrelograms Crosscorrelation Imaging Condition

Depth (ft) Well dataXcorr. Migration Field Data

Depth (ft) Well dataStandard Migration Exxon Data

Above Source Imaging{ Wider Coverage VSP Interferometric Summary Wider, taller coverage. Eliminates well statics and uninteresting parts of the medium. M M m(x) = (g, t + t ) gx g MxMxMxMxgx Kirchhoff Migrate psuedo-shot gathers Kirchhoff Migrate psuedo-shot gathers

Shifting Traces Removes Kinematic Effects Of Propagating through Uninteresting Parts of Medium.. M M M m(x) = (g, t + t ) gx g MxMxMxMxgx Kirchhoff Migrate psuedo-shot gathers Kirchhoff Migrate psuedo-shot gathersg Source Moved to Depth Can replace time-shifted traces by crosscorrelograms

m Distance (km) 010 CDP Interferometric Imaging Depth (km) 10 Distance (km) Model KM image with Incorrect velocity km/s Datuming with Reflections sg

m Distance (km) 010 CDP Interferometric Imaging Depth (km) 10 Distance (km) Model KM image with Incorrect velocity km/s Datuming with Reflections sg

m Distance (km) 010 CDP Interferometric Imaging Depth (km) 10 Distance (km) Model KM image with Incorrect velocity km/s Datuming with Reflections sg