Super-virtual interferometry Fuqiang Chen Ahmed Zidan

Data and acquisition parameters Goal: Detect Qadema fault and subsurface geology. Acquisition parameters: Shot number=240. Receiver number=240@Shp. Shot interval=5m. Receiver interval=5m. Line length=1200m.

Problem Problems: Data are very noisy. Can’t pick first arrival. Picking far offset is impossible. Tomogram result is not good. Courtesy(Aydar Zaripov,2015)

Theoretical Aspects of SVI Super Virtual Interferometry and its implementation. Shuqian Dong, Jianming Sheng and Jerard T. Schuster

SVI: Numerical Tests Spike test. 2 common receiver gathers (9 traces). Orange line represents original signal and blue line represents enhanced signal using SVI. Conclusion: For spike signal and refracted arrival of linear T-X curve, SVI can perfectly recover it with amplification.

SVI: Numerical Tests Original signal (upper) and noise signal (lower). The maximal amplitude of signal is 0.4. The maximal amplitude of random noise is 80. 27 sources and two common receiver gathers are used to enhance the virtual signal

SVI: Numerical Tests The 1st common receiver gather with 80 times noise (upper) and signal of S/N enhanced by SVI with lucky window. Original signal is 3 points [….. * * * …..]. Lucky window is […@@***@@...]

SVI: Numerical Tests The results of lucky window (upper) and (15 points) unlucky window (lower). 17th trace of true data(green), noise-adding data(red) and recovered data using SVI (blue).

SVI: Numerical Tests Shot 21st before SVI (upper) and after SVI (lower)

SVI: Numerical Tests Shot 57th before SVI (upper) and after SVI (lower)

proposed solutions Solutions: Process the data to enhance SNR. Try SVI technique.

Processing Flow Karhunen-Loeve Filtering Amplitude Correction(Gain) FX-Deconvolution 2D Weiner filter FK Filter 1D median filter

Karhunen-Loeve Filtering Why???????? 50 m offset(right) 50 m offset(left)

Karhunen-Loeve Filtering In Common Offset Domain. Enhance Coherency. Parameters: Operator length=20, For left hand side. Operator length=40, For right hand side. Reference: M.D Sachi, SAIG, 2008

Karhunen-Loeve Filtering 50 m offset(right) 50 m offset(left)

Karhunen-Loeve Filtering Shot # 120

Amplitude Correction Focus energy around the first arrival. Parameters: function: 𝑡 𝑎 × 𝑒 −𝑏𝑡 . Reference: M.D Sachi, SAIG, 2008

Amplitude Correction Shot # 120

FX-Deconvolution Remove the random noise. Random noise bursts along the whole frequency spectrum. “Bandpass filter is ineffective ”. Parameters: Fmax=70Hz Fmin=20Hz Reference: M.D Sachi, SAIG, 2008

FX-Deconvolution Why FX-Deconvolution ???????? Why not Bandpass filter ??????

FX-Deconvolution Shot # 120

2D Adaptive Weiner Filter Smooth the frequency spectrum. Smooth the amplitude anomalies. Parameters: 9 samples in time. 2 samples in space.

2D Adaptive Weiner Filter Shot # 120

FK Filter Removes Linear noise. But, we kept linear events and remove every other events. Parameters: Path #1 remove events (Vmin=4000, Vmax=inf). Path #2 remove events(Vmin=100, Vmax=400). Reference: G.F. Margrave, CREWES, 1991.

FK Filter Shot # 120

1D median filter Remove FK residuals. Parameters: 8th order filter.

1D median filter Shot # 120

SVI SVI- Preconditioning Done on Right and Left hand-side separately. Window around first arrival. Shot # 160

SVI- Left hand side (mid offset) Shot # 160

SVI- Left hand side (Far offset) Shot # 160

SVI- right hand side (Far offset) Shot # 160

Conclusion And Recommendation Processing enhances the coherency of the data and enhance SNR. SVI works well till mid offset (85m). Recommendation: Further data processing is required to enhance SNR for far offset. Run SVI for far offset. Perform reflection processing to estimate the NMO velocity.