Interferometric Multiple Migration of UPRC Data Jianhua Yu University of Utah

Outline  Motivation and Objective  Interferometric Migration: Crosscorrelogram migration Autocorrelogram migration  Examples Synthetic Data UPRC data  Summary

Outline Motivation and Objective  Interferometric Migration: Crosscorrelogram migration Autocorrelogram migration  Examples Synthetic Data UPRC data  Summary

IVSPWD Objective ?  Provide Look-ahead Image Below Drill Bit  Reduce Uncertainty in Drilling ?

Problem Deviated Well  No Source Wavelet  No Source Initiation Time  Not Easy to Get Pilot Signal in Deviated Well

Solution Interferometric Migration No need to know source wavelet No need to know source location No need to know initial time No limits to deviated well

Outline. Motivation and Objective. Interferometric Migration. Examples Outline . Motivation and Objective . Interferometric Migration . Examples . Summary

. Crosscorrelogram migration . Autocorrelogram migration Interferometric Migration . Crosscorrelogram migration . Autocorrelogram migration

Primary, Ghost and Direct Wave Well Receiver Ghost Direct Wave Primary Drill bit Primary, Ghost and Direct Wave

Free-surface related Ghost Travel Time x

Ghost Imaging Condition After Correlation of Traces: x g s g’ Condition: recording data have to be dense !!

Crosscorrelogram Ghost Imaging Condition: x g s g’

Crosscorrelogram Migration Migrated Image Crosscorrelation Function

. Crosscorrelogram migration . Autocorrelogram migration Interferometric Migration . Crosscorrelogram migration . Autocorrelogram migration

Free-surface related Ghost Travel time: x

Autocorrelogram Ghost Imaging Condition: x

Autocorrelogram Migration Migrated Image Autocorrelation Function

Outline. Motivation and Objective. Autocorrelogram Migration Method Outline . Motivation and Objective . Autocorrelogram Migration Method . Examples . Summary

Geological Model X (m) 4 V1 V2 Depth (m) V3 V4 V5 V6 3

Velocity Model X(km) X(km) 0 4 0 4 Depth(km) 3 3 Interval Velocity 0 4 0 4 3.5 3.5 Depth(km) 2.0 2.0 3 3 Interval Velocity RMS Velocity

Shot Gather and Crosscorrelogram Traces Traces 1 200 1 200 Time (s) Time (s) 4 4 CSG 10 and Master trace at 80

Shot Gather and Autocorrelogram Traces Traces 1 200 1 200 Time (s) Time (s) 4 4 CSG 10

Crosscorrelogram Migration Results X (km) X (km) 1.6 2.1 1.6 2.1 Time (s) 2.2 With primary Without primary

Autocorrelogram Migration Results X (km) X (km) 1.6 2.1 1.6 2.1 Time (s) 2.2 With primary Without primary

Acquisition Survey East (kft) North (kft) 3C Receivers Depth (kft) 4.5 4.5 Drill bit North (kft) Well Rig 3C Receivers -5 Depth (kft) 10

Main Acquisition Parameters Drill-bit Depth: 9188 ft Offset Range: 1135-4740 ft Recording Length: 20 s Sample Interval: 2 ms Station Number: 10

Drill-bit Data of CSG #96 Trace Number 1 10 Time (s) 7

Main Processing Steps Frequency panel analysis and noise elimination Trace editing and static shift Frequency panel analysis and noise elimination Amplitude balance and energy normalization Velocity analysis Calculating cross- and autocorrelograms, vertical stacking Cross- and Autocorelogram migration

Frequency Panel Analysis 1 10 1 10 Time (s) Time (s) 7 7 5-15 Hz < 5 Hz

Frequency Panel Analysis 1 10 1 10 Time (s) Time (s) 7 7 25-40 Hz 15-25 Hz

Processed CSG 96 Part of CRG 6 1 10 1 13 0.5 Time (s) Time (s) 7 4.5

Crosscorrelogram of CSG 96 Trace No. 1 10 1 10 1 10 Time (s) 4 8 s 12 s 16 s

Autocorrelogram of CSG 96 1 10 1 10 1 10 Time (s) 4 8 s 12 s 16 s

Autocorrlogram Migration Images Traces Traces 1 50 1 50 0.5 Time (s) 3.2 Window = 8 s Window=12 s

Crosscorrlogram Migration Images Traces Traces 1 50 1 50 0.5 Time (s) 3.2 Window = 8 s Window=12 s

Acquisition Survey Map Well Rig Line AC4 North (ft) Drill bit 3C Receivers -5000 1500 3000 4500 East (ft)

Autocorrelation Ghost Image(Corr. Window=8 s) SP 1255 1235 1215 1.0 Drilling hole Time (s) 2.0 3.0 Autocorrelation Ghost Image(Corr. Window=8 s)

Crosscorrelation Ghost Image ( Corr. Window 12 s) SP 1255 1235 1215 1.0 Drilling hole Time (s) 2.0 3.0 Crosscorrelation Ghost Image ( Corr. Window 12 s)

Outline . Objective . Autocorrelogram Migration . Examples . Summary 

SUMMARY Crosscorr. and autocorrelogram migration works for deviated well All result are comparable to surface-CDP section No source position is needed for crosscorrelogram migration Dense recording data is necessary for crosscorrelation migration to get good quality image

SUMMARY Difficulty of separating upgoing and downgoing wave can cause artifacts in migration image

What’s Next Improve the method’s efficiency for real-time purpose Reduced the virtual multiple and other wave’s influence Integrated migration image of both borehole data and CDP data

Acknowledgements I greatly appreciate Union Pacific Resources for donating this data I am grateful to the 2000 sponsors of the UTAM consortium for financial support I also thank all of people who give me some suggestions and help for this work