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Critical Wavepath Refraction Migration. Maike Buddensiek, University of Utah, Feb. 2003. Outline. Introduction - Why are we doing this? Basic concept of CRRM method Results of synthetic data Conclusions and further research. Introduction.
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Critical Wavepath Refraction Migration Maike Buddensiek, University of Utah, Feb. 2003
Outline • Introduction - Why are we doing this? • Basic concept of CRRM method • Results of synthetic data • Conclusions and further research
Introduction • Refraction data contain hidden information of reflection traveltimes. • After resorting the data, they are kinematical equivalent to critical reflections. • Those critical refractions can be migrated just like reflections. • Less artifacts • Velocity of refracting layer not necessary • Any refractor geometry can be migrated
v1 v2 TAY TAY + TBX - TAB TAY + TBX BasicConcept A X M Y B TAY + TBX - TAB
v1 v2 BasicConcept BasicConcept A X M Y B TAY TAY + TBX - TAB TAY + TBX TAY + TBX - TAB
v1 v2 BasicConcept BasicConcept A X M Y B TAY TAY + TBX - TAB TAY + TBX TAY + TBX - TAB
v1 v2 BasicConcept BasicConcept A X M Y B TAY TAY + TBX - TAB TAY + TBX TAY + TBX - TAB = TXY TAY + TBX - TAB
Critical Distance v1 v2 BasicConcept A X M Y B O TAY + TBX - TAB = TXY TXYdata : kinematics of reflection
v1 v2 O TXO + TOY = TXOYtheory Migration by Raytracing A X M Y B
v1 v2 Incidence Angles for Raytracing A X M Y B
v1 v2 O Migration by Raytracing A X M Y B TXOYtheory TXYdata
Critical Distance v1 v2 Migration by Raytracing A X M Y B O TXOYtheory = TXYdata
v1 v2 A X M Y B CRRM Method • 1. Select A, B, X, Y and then trace rays • 2. Determine TXOYtheory • 3. Determine TXYdata • 4. If TXYdata = TXOYtheory • Smear refraction energy at O. • Otherwise no energy is smeared. O
Dipping Layer Model 1 600 300
Dipping Layer Model 2 600 300
Low Frequency Undulation 600 300
High Frequency Undulation 600 300
Fault Model 600 300
Results • Very accurate mapping of the refractors • No artifacts • The refracting velocity is not known • Problemaict zones just result in unmapped traces
Conclusion • The CRRM method has the potential to migrate refraction data more precisely than traditional methods. • CRRM does not produce artifacts like traditional methods do. • Future Work: Make suggested changes and then apply to field data.