Direct detection of near-surface faults by migration of back-scattered surface waves Han Yu, Bowen Guo*, Sherif Hanafy, Fan-Chi Lin**, Gerard T. Schuster King Abdullah University of Science and Technology Center for Subsurface Imaging and Fluid Modeling (CSIM) ** The University of Utah October 29, 2014

Outline Motivation: Near-surface fault detection Methodology : Migrate back-scattered surface waves Numerical results: Synthetic and field data Future Work

Outline Motivation: Near-surface fault detection Methodology : Migrate back-scattered surface waves Numerical results: Synthetic and Aqaba data Future Work

Motivation: detect near-surface fault by migrating surface waves 2.8 km/s Depth (m) 0.3 km/s 50 300 Distance (m) P Wave Velocity Tomogram

Outline Motivation: Near-surface fault detection Methodology : Migrate back-scattered surface waves Numerical results: Synthetic and Aqaba data Future Work

Methodology: migrate back-scattered surface wave Why surface waves? Strong amplitude. Traveling near-surface. No need for surface wave velocity for migration for dense source and receiver distribution

Methodology: migrate back-scattered surface wave Src: s Rec: g xf: Fault Position Back-scattered Surface Waves Fault Source and Receiver Positions Geometrical spreading from the scatter location to receiver Back-scattered Reflection Coefficient

Methodology: migrate back-scattered surface wave s: source g: receiver x: Trial Image Point Fault Direct surface wave from s to x Direct surface wave from x to g Back scattered surface wave De-dispersion term

Methodology: migrate back-scattered surface wave No need for surface wave velocity   s: source g: receiver x: Trial Image Point Fault

Work flow Step 0: mute body wave Step 1: filter out back-scattered surface wave Step 2: migrate back-scattered surface wave

Outline Motivation: Near-surface fault detection Methodology : Migrate back-scattered surface waves Numerical results: Synthetic and Aqaba data Future Work

Synthetic Example (Guo et al., 2014)

Field Example 3 4 1 2 a). Common Shot Gather #20 c). Prestack Migration Images Shot Number 0.8 1 Not very clear back-scattered surface wave Time (s) 120 0.0 297 297 Stacked Migration Image b). F-K Filtered Shot Gather #20 0.8 d). Tomogram and COG Depth (m) 2.7 km/s Time (s) 3 4 1 2 50 0.3 km/s Time (s) 0.0 297 0.08 X (m) 297

Outline Motivation: Near-surface fault detection Methodology : Migrate back-scattered surface waves Numerical results: Synthetic and Aqaba data Future Work

Future Work More robust way to filter out back-scattered surface wave Extension to 3D case

Thanks to the 2014 sponsors of the CSIM consortium Thanks to the 2014 sponsors of the CSIM consortium. Thanks to the HPC center of King Abdullah University of Science and technology . Thank you !