6 months at CWP: Done a lot, but not done yet Or: how to deal with black magic by Dr. Ernst Niederleithinger Senior Scientist and Deputy Division Leader at BAM( Federal Institute for Materials Research and Testing) Berlin, Germany Visiting Research Professor at Colorado School of Mines CWP Seminar, Niederleithinger 1

Motivation to come here: But there was more than that! CWP Seminar, Niederleithinger 2

Content Things to be cared about in geophysics and NDT: Events Changes Images Where to go from here? CWP Seminar, Niederleithinger 3

Events Seismics: Earthquakes, fracking,…. Concrete: Load induced cracks,… Localization, Characterization CWP Seminar, Niederleithinger 4

Events One tool: Time Reversal (Fink et al.) Reciprocity Inject time reversed signals at receivers Energy will focus at source CWP Seminar, Niederleithinger 5

Events One tool: Time Reversal (Fink et al.) Reciprocity Inject time reversed signals at receivers Energy will focus at source Improvement? Deconvolution! CWP Seminar, Niederleithinger 6

Does it really work? Experiment! CWP Seminar, Niederleithinger 7

Does it really work? Experiment! CWP Seminar, Niederleithinger 8

Setup: forward CWP Seminar, Niederleithinger 9

Data: forward CWP Seminar, Niederleithinger 10

Setup: backwards CWP Seminar, Niederleithinger 11

Data: backward CWP Seminar, Niederleithinger 12

Focus! CWP Seminar, Niederleithinger 13

Next topic: Changes Seismics: stress, oil/gas content,…. Concrete: stress, degradation,…. Both: Detect it as early as possible! „Global“ changes: Coda Wave Interferometry Localization? Ideas by Pacheco & Snieder, Larose, Sens-Schönfelder,…. CWP Seminar, Niederleithinger 14

Simple experiments: subtle changes detected, but no localization! CWP Seminar, Niederleithinger 15

Localization is possible! CWP Seminar, Niederleithinger 16

Don’t believe it? Experiment! CWP Seminar, Niederleithinger 17

Don’t believe it? Experiment! CWP Seminar, Niederleithinger 18

Don’t believe it? Experiment! CWP Seminar, Niederleithinger 19

Results (“simple” CWI) CWP Seminar, Niederleithinger 20

Results (“simple” CWI) CWP Seminar, Niederleithinger 21

Preliminary Results (“advanced” CWI) CWP Seminar, Niederleithinger 22

Preliminary Results (“advanced” CWI) CWP Seminar, Niederleithinger 23

Last but not least: Imaging Seismics: Layers, structures, hydrocarbons Concrete: rebars, tendons, voids, cracks,… Both: Mapping (multiple) reflections recorded close to/at the surface to where they belong! Same math+physics! CWP Seminar, Niederleithinger 24

RTM Ultrasonic black magic in TV CWP Seminar, Niederleithinger 25

SAFT imaging Main contributors to SAFT: Langenberg, Mayer, Marklein, University of Kassel Friese et al., SMT 2008 Synthetic aperture focusing technique Family of methods Constant and multi-offset data Direct reflections only Phase evaluation possible (Krause et al., SF&R 2008) CWP Seminar, Niederleithinger 26

Reverse Time Migration! Sabine Müller Ernst Niederleithinger Maria Grohmann Martin Krause Thomas Bohlen Paul Sava CWP Seminar, Niederleithinger 27

Synthetic example 1 RTM Model used for simulating data Velocity model for migration RTM result CWP Seminar, Niederleithinger 28

Off to Horstwalde Foundation slab at our test site CWP Seminar, Niederleithinger 29

Off to Horstwalde CWP Seminar, Niederleithinger 30

Off to Horstwalde CWP Seminar, Niederleithinger 31

Off to Horstwalde Simulations CWP Seminar, Niederleithinger 32

Off to Horstwalde Real data CWP Seminar, Niederleithinger 33

Back to the lab Measurements: Polyamide block, (100*60*30 cm³) Point contact transducers in arrays of 4 P, SHx, SHy CWP Seminar, Niederleithinger 34

Back to the lab CWP Seminar, Niederleithinger 35

Back to the lab CWP Seminar, Niederleithinger 36

Seismic Interferometry Reconstruction of Greens functions Data, where you think you don‘t have data Gerald Schuster Roel Snieder Kees Wapenaar CWP Seminar, Niederleithinger 37

„Green‘s function retrieval“, „Seismic Interferometry“ Trace interpolation, synthetic example (44 sources) Seismic Interferometry CWP Seminar, Niederleithinger 38

„Green‘s function retrieval“, „Seismic Interferometry“ Trace interpolation, synthetic example (44 sources) Seismic Interferometry CWP Seminar, Niederleithinger 39

„Virtual Real Source“ (Behura, 2006) synthetic example (11 sources) Seismic Interferometry CWP Seminar, Niederleithinger 40

Back to the lab Just more black magic? Experiment! (on the way) CWP Seminar, Niederleithinger 41

That will be simple. Reality is much more complicated: CWP Seminar, Niederleithinger 42

Let‘s steal another black magic idea: Autofocusing CWP Seminar, Niederleithinger 43

Let‘s steal another black magic idea: Autofocusing CWP Seminar, Niederleithinger 44