Depth (m) Time (s) Raw Seismograms Four-Layer Sand Channel Model Midpoint (m)

Interferometric Seismic Imaging Jianhua Yu & Gerard T. Schuster University of Utah

Outline Passive data for IVSP while Drilling Imaging of Free Surface CDP Multiples Interferometric Principle: Interferometric Principle: Time Diff. between Arrivals Structure Diff. Interferometric Imaging Applications: Interferometric Imaging Applications:

Claerbout, Katz, 70’s xx Earthquake 1900’s xx Utah+LLNL 1997 Migrate Claerbout, Rickett 1999 xyxyxyxy xyxyxyxyMigrate Arbitrary Unknown Src V(z) V(x,y,z) W(t) Location W(t) Location NOYESYESYES NO YESYESYES YES/NO YESNO? NOYESYES YESNO YES YES YES SELECTIVE HISTORY PASSIVE IMAGING Validity

Interference Pattern Optical Lens LASER t

Interference Pattern Optical Lens ss t LASER Lens Deformation Time Differences

Outline Passive data for IVSP while Drilling Interferometric Principle: Interferometric Principle: Time Diff. between Arrivals Structure Diff. Interferometric Imaging Applications: Interferometric Imaging Applications:

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

Source Geophone Bit Position? Problems in RVSPWD Pilot signal? Wavelet ?

Problems with Drill-bit and RVSP Data No source wavelet No source initiation time Not easy to get pilot signal in deviated well Not easy to get pilot signal in deviated well and horizontal well

Static shift errors may exist Difficulty for separating primary and ghost waves from deviated or horizontal well Problems with Drill-bit and RVSP Data

Solution Cross- or Auto-correlogram Migration Why do we use autocorrelation of seismic data rather than the seismogram ???

Strengths of Autocorrelogram Migration No need to know initial time No limits to deviated well Reduce Static errors influence No need to know source wavelet

Weakness of Correlogram Migration Virtual Multiples & Loss of Resolution

Well Drill bit Receiver Primary Direct Wave Ghost What is Joint Migration

Final migration image Ghost migration Primary migration Seismic Data

Horizontal Well Model 0 Depth (m) 3 40 X (m) V1 V2 V4 V3 V5 V6

Shot Gather Time (s) CSG Time (s) Traces Autocorrelogram

Depth (km) X (km) X (km) Standard migration Joint migration Standard Migration with Joint Migration (3 CSGs) Source

Time (s) X (km) X (km) With only primaryJoint auto. migration Time Migration Results (39 CSGs) Source

East (kft) North (kft) Well Rig 10 Depth (kft) ft Offset= ft Recording Length: 20 s Sample Interval: 2 ms Main Acquisition Parameters

Main Processing Steps Trace editing and static shift Trace editing and static shift Frequency panel analysis and noise elimination Frequency panel analysis and noise elimination Velocity analysis Velocity analysis Amplitude balance and energy normalization Autocorrelograms, vertical stacking utocorelograms Joint migrating autocorelograms

Acquisition Survey Map Well Rig 3C Receivers Drill bit East (ft) North (ft) C Line AC4

Time (s) SP Drill hole Joint Migration ( insert) and CDP Section

Time (s) SP Primary Migration ( insert) and CDP Section Drill hole

Time (s) SP Drilling hole Joint Migration ( insert) and CDP Section JOINT

Time (s) SP Primary Migration ( insert) and CDP Section Drilling hole Primary

SUMMARY Need separating primary and multiple? NO Work for deviated or horizontal well ? YES Reduce the influence of static errors ? YES Need pilot signal ? NO Need source wavelet and initial time ? NO Suppress coherent noise ? YES Amplitude fidelity ? NO Virtual Multiple ? YES

Thanks to UTAM sponsors and DOE. and DOE. Thanks to Lew Katz and Fred Followill.

Primary Ghost 12 Free-Surface Multiple

Primary Ghost 12 x PrimaryxPrimary Seismic Interferogram: Correlate Traces Caution: Ghostx Primary = R 3 t } m(x) = (g, t + t ) gx g MxMxMxMxgx M Kirchhoff Migrate psuedo-shot gathers Kirchhoff Migrate psuedo-shot gathers Ghost Primary has kinematics of primary ref. x

Nine-Layered Model (J. Sheng) Depth (km) 2.4 Model Crosscorrelogram image Distance (km) Distance (km) artifacts Kirchhoff Image

Nine-Layered Model Kirchhoff Image Product Image =Kirch*correl Depth (km) 2.4 Distance (km) Distance (km) artifacts

SEG/EAGE Salt Model Depth (km) Distance (km)

Crosscorrelogram Image Crosscorrelogram Image Depth (km) Distance (km)

Kirchhoff Image Depth (km) Distance (km)

Product Image Depth (km) Distance (km)