Primary-Only Imaging Condition Yue Wang

Outline Objective Objective POIC Methodology POIC Methodology Synthetic Data Tests Synthetic Data Tests 5-layer model 5-layer model salt dome model salt dome model Unocal Field Data Tests Unocal Field Data Tests Discussion and Future Work Discussion and Future Work

Synthetic Shot Gather Distance (m) Time (s) Multiples Primary

2D Kirchhoff migration * ^ Source Receiver  obs  obs =  SA +  RA  SA  RA

Kirchhoff Migration Image Artificial Multiple Image Distance (km) Depth (km)

Problem Standard imaging condition Standard imaging condition Data Data ( primary + multiple ) Image

Objective Primary-Only imaging condition Data Data ( primary + multiple ) Image

Outline Objective Objective POIC Methodology POIC Methodology Synthetic Data Tests Synthetic Data Tests 5-layer model 5-layer model salt dome model salt dome model Unocal Field Data Tests Unocal Field Data Tests Discussion and Future Work Discussion and Future Work

MethodologyData Primary Multiple = + First-order Multiple Second-order Multiple Third-order Multiple

Methodology Primary Multiple ? What Differences What Differences

Primary Reflections Offset Depth * ^ Source Receiver A

Multiple Reflections Offset Depth * ^ Source Receiver A C B

Methodology For a specific event: Observed traveltime  obs Observed traveltime  obs shooting angle  shooting angle  incident angle  incident angle 

Shoot ray from source Offset Depth * ^ Source Receiver 

Offset Depth * ^ Source Receiver  Shoot ray from receiver

Find crossing point Offset Depth * ^ Source Receiver Cross point A  SA  RA  

Primary-Only Imaging Condition (POIC) One event is primary reflection only if :  obs =  SA +  RA  obs =  SA +  RA

Multiple Reflections Offset Depth * ^ Source Receiver A  SA  RA  

Multiple Reflections  obs =  SA +  RA  obs =  SA +  RA

Methodology Data Data ( primary + multiple ) Standard Imaging Condition  obs Image ( primary + multiple ) Primary Only Imaging Condition  obs,  and  Image ( primary + multiple )

Outline Objective Objective POIC Methodology POIC Methodology Synthetic Data Tests Synthetic Data Tests 5-layer model 5-layer model salt dome model salt dome model Unocal Field Data Tests Unocal Field Data Tests Discussion and Future Work Discussion and Future Work

5-Layer Model Distance (km) Depth (km) * Source Geophone Line

Shot Gather Distance (m) Time (s) P1 P2 P3 P4

Kirchhoff Migration Image Distance (km) Depth (km)

Kirchhoff Migration Image Artificial Multiple Image Distance (km) Depth (km)

Migration Image with POIC Distance (km) Depth (km)

Outline Objective Objective POIC Methodology POIC Methodology Synthetic Data Tests Synthetic Data Tests 5-layer model 5-layer model salt dome model salt dome model Unocal Field Data Tests Unocal Field Data Tests Discussion and Future Work Discussion and Future Work

Salt Model Distance (km) Depth (km) * Source Geophone Line

Shot Gather Distance (m) Time (s)

Kirchhoff Migration Image A.M.I. Distance (km) Depth (km) A.M.I.

Migration Image with POIC Distance (km) Depth (km)

Outline Objective Objective POIC Methodology POIC Methodology Synthetic Data Tests Synthetic Data Tests 5-layer model 5-layer model salt dome model salt dome model Unocal Field Data Tests Unocal Field Data Tests Discussion and Future Work Discussion and Future Work

Processed CSG Distance (m) Time (s) M1 M2

NMO Corrected CMG Distance (m) Time (s) M2

CMG after Dip Filtering CMG after Dip Filtering Distance (m) Time (s) M2

Seismogram in  -p Domain Seismogram in  -p Domain p Time (s) Multiple Primary

Muting in  -p Domain Muting in  -p Domain p Time (s)

CMG after Muting in  -p CMG after Muting in  -p Distance (m) Time (s) M2

Stack before Muting Time (s) 0 4 M1 CDP Number M2

Stack after Muting Time (s) 0 M2 CDP Number

Kirchhoff Image Depth (m) M1 M2 Distance (m)

POIC Image Depth (ft) M1 M2 Distance (m)

Conclusions POIC Works for synthetic data POIC Works for synthetic data Encouraging results for field data Encouraging results for field data POIC need more accurate velocity model POIC need more accurate velocity model

Future Work Apply to other field data Apply to other field data Improve velocity model estimate Improve velocity model estimate

Acknowledgement We are grateful to the 1999 sponsors of the UTAM consortium for the financial support

Migration with POIC Four Steps: (1) pick seismic events automatically;  obs  obs

Migration with POIC Four Steps: (2) calculate incidence and shooting angles  and  for one event using local slant stack;

Migration with POIC Four Steps: (3) ray tracing and find the crossing point;  SA +  RA  SA +  RA

Find crossing point Offset Depth * ^ Source Receiver Cross point A  SA  RA  

(4)  obs =  SA +  RA ? No: Discard this event; No: Discard this event; Yes: Migrate this event; Yes: Migrate this event; Migration with POIC

Raw CSG Distance (m) Time (s)

CMG Offset (m) Time (s) M1 M2