Autocorrelogram Migration for Field Data Generated by A Horizontal Drill-bit Source Jianhua Yu, Lew Katz Fred Followill and Gerard T. Schuster
Outline Motivation and Objective Motivation and Objective Autocorrelogram Migration Autocorrelogram Migration Examples Examples Summary Summary
Outline Motivation and Objective Motivation and Objective Autocorrelogram Migration Autocorrelogram Migration Examples Examples Summary Summary
IVSPWD Objective Provide Look-ahead Image Below Drill Bit Provide Look-ahead Image Below Drill Bit Reduce Uncertainty in Drilling Reduce Uncertainty in Drilling ?
Problems No Source Wavelet No Source Wavelet No Source Initiation Time No Source Initiation Time Not Easy to Get Pilot Signal in Not Easy to Get Pilot Signal in Deviated Well Deviated Well
Autocorrelogram Migration No need to know source wavelet No limits to a deviated well No need for initiation time Solution
Outline Outline Motivation and Objective Motivation and Objective Autocorrelogram Migration Autocorrelogram Migration Examples Examples Summary Summary
Well Drill bit Receiver Primary wave Primary, Ghost and Direct Wave Direct Wave Ghost
x g s Primary Autocorrelogram Imaging Condition:
x g s
g Ghost Autocorrelogram Imaging Condition Ghost Autocorrelogram Imaging Condition: x s g’
x g s Ghost Autocorrelogram Imaging Condition Ghost Autocorrelogram Imaging Condition:
Autocorrelogram Migration Migrated Image Autocorrelation Function
Outline Outline Motivation and Objective Motivation and Objective Autocorrelogram Migration Autocorrelogram Migration Examples Examples Summary Summary
Acquisition Survey East (kft) North (kft) Well Rig 3C Receivers Drill bit 10 Depth (kft) 0
Main Acquisition Parameters Drill-bit Depth: 9188 ft Offset Range: ft Recording Length: 20 s Sample Interval: 2 ms Station Number: 10
Main Processing Steps Orienting receivers, trace editing, and static shift Orienting receivers, trace editing, and static shift Frequency panel analysis and noise elimination Frequency panel analysis and noise elimination Velocity analysis and beam steering Velocity analysis and beam steering Amplitude balance and energy normalization Calculating autocorrelograms, vertical stacking Calculating autocorrelograms, vertical stacking Autocorrelogram migration
Raw Data Frequency Panel Analysis Time (s) Time (s) < 5 Hz 5-15 Hz
Time (s) Time (s) Hz Hz Raw Data Frequency Panel Analysis
Processed CSG 96 Part of CRG Time (s) Time (s)
Autocoreelograms Associated With CRG Time (s)
Primary Image Time (s) 501 Ghost Image Autocorrlogram Migration Images Traces Traces No reflections
Acquisition Survey Map Well Rig 3C Receivers Drill bit East (ft) North (ft) C Line AC4
Time (s) SP Drilling hole Primary Image with CDP Section
Time (s) SP Ghost Image with CDP Section (Reverse Polarity) Drilling hole
Outline Outline Motivation and Objective Motivation and Objective Autocorrelogram Migration Autocorrelogram Migration Examples Examples Summary Summary
SUMMARY Autocorrelogram Migration works for deviated well Primary autocorrelogram image correlates well with the surface- CDP section Ghost autocorrelogram migration result is comparable to surface-CDP section but suffers from more noise
SUMMARY The upgoing and downgoing wave separation can cause some artifacts in migration image
Acknowledgements We greatly appreciate DOE for Financial supportWe greatly appreciate DOE for Financial support We are grateful to Union Pacific Resources for donating this dataWe are grateful to Union Pacific Resources for donating this data I am grateful to the 1999 sponsors of the UTAM consortium for financial supportI am grateful to the 1999 sponsors of the UTAM consortium for financial support