3-D Migration Deconvolution: Real Examples Jianhua Yu University of Utah Bob Estill Unocal

Motivation Outline 3-D Migration Deconvolution (MD) Examples Conclusions

Motivation Outline 3-D Migration Deconvolution (MD) Examples Conclusions

3-D prestack time migration data Unocal 3-D data from Alaska 2002 Winter:

3.0 Mig in Inline (Courtesy of Unocal) MD Times (s) 1.2

3-D prestack time migration data 3-D prestack depth migration data 2003 Summer: Unocal 3-D data from Alaska 2002 Winter: Does MD work equally well for both time and depth migration? 3-D prestack depth migration data 2003 Summer:

Objectives : Improve spatial resolution Enhance illumination Suppress migration noise and artifacts Apply 3-D migration deconvolution in depth domain

Motivation Outline 3-D Migration Deconvolution (MD) Examples Conclusions

T R = (L L ) m R = (L L ) m Migration Deconvolution Theory Migration Green’s function (Schuster and Hu, 2000) MD efficiently eliminates the blurring influence in the migration image

Migration Green’s function (Schuster and Hu, 2000) Migration Deconvolution Theory

MD Implementation Steps: Step 1: Prepare traveltime table Acquisition geometry information Velocity Step 2: Calculate the migration Green’s function at the depth Zi

For the discrete MD equation: FFT of Migrateddata True Reflectivity

Step 4: Obtain MD image at the depth Z i by solving following equation Step 5: Repeat Steps 2-4 until the maximum depth is finished Step 6: IFFT of MD image from wavenumber domain to space domain

Motivation Outline 3-D Migration Deconvolution (MD) Examples Conclusions

3-D Land Field Data : Receiver : source

Mig (Courtesy of Unocal) MD Inline Number Crossline Number Inline Number (2 kft)

1.1 Depth (kft) Crossline Number (Inline =50) Fault

(3.08 kft) Inline Number Crossline Number Inline Number MigMD

(3.6 kft) Inline Number Crossline Number Inline Number Mig MD

Inline Number Depth (kft) 90Inline Number1 Mig (courtesy of Unocal)MD (Crossline=50)

Inline Number Depth (kft) 90Inline Number1 (Crossline=50) Mig (courtesy of Unocal)MD

Mig in Inline (Courtesy of Unocal) MD Times (s)

(crossline 200) Depth (kft) Mig (courtesy of Unocal)MD Inline Number

(crossline 200) Depth (kft) Mig (courtesy of Unocal)MD Inline Number

Depth (kft) Y (kft) (X=11.2 kft) Mig MD

Motivation Outline Migration Deconvolution (MD) Examples Conclusions Implementation of MD

Conclusions Improve resolution and suppress migration artifacts MD cost is related to acquisition geometry Little improvement in the deeper part of migration image

Thanks To Aramco, Unocal, and Chevron-Texaco for providing the field dataAramco, Unocal, and Chevron-Texaco for providing the field data 2003 UTAM sponsors2003 UTAM sponsors Alan Leeds (ChevronTexaco), and George Yao (Unocal)Alan Leeds (ChevronTexaco), and George Yao (Unocal) CHPCCHPC